WO2021032118A1 - 域名系统查询的方法和通信装置 - Google Patents

域名系统查询的方法和通信装置 Download PDF

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Publication number
WO2021032118A1
WO2021032118A1 PCT/CN2020/110009 CN2020110009W WO2021032118A1 WO 2021032118 A1 WO2021032118 A1 WO 2021032118A1 CN 2020110009 W CN2020110009 W CN 2020110009W WO 2021032118 A1 WO2021032118 A1 WO 2021032118A1
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WO
WIPO (PCT)
Prior art keywords
network element
terminal device
domain name
address
smf
Prior art date
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PCT/CN2020/110009
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English (en)
French (fr)
Inventor
朱方园
李岩
倪慧
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201910926424.3A external-priority patent/CN112422701B/zh
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP20854428.8A priority Critical patent/EP4016962A4/en
Priority to MX2022002151A priority patent/MX2022002151A/es
Publication of WO2021032118A1 publication Critical patent/WO2021032118A1/zh
Priority to US17/675,301 priority patent/US11689496B2/en
Priority to US18/316,768 priority patent/US20230370419A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/26—Network addressing or numbering for mobility support
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/45—Network directories; Name-to-address mapping
    • H04L61/4505—Network directories; Name-to-address mapping using standardised directories; using standardised directory access protocols
    • H04L61/4511—Network directories; Name-to-address mapping using standardised directories; using standardised directory access protocols using domain name system [DNS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/121—Shortest path evaluation by minimising delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/74—Address processing for routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/50—Address allocation
    • H04L61/5007—Internet protocol [IP] addresses
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/141—Setup of application sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/14—Session management
    • H04L67/146—Markers for unambiguous identification of a particular session, e.g. session cookie or URL-encoding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/52—Network services specially adapted for the location of the user terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/55—Push-based network services
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2101/00—Indexing scheme associated with group H04L61/00
    • H04L2101/60—Types of network addresses
    • H04L2101/69—Types of network addresses using geographic information, e.g. room number
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/12—Setup of transport tunnels

Definitions

  • This application relates to the field of communications, and more specifically, to a method and communication device for querying a domain name system.
  • the terminal device may send a domain name resolution request to the DNS server.
  • the domain name resolution request carries the domain name
  • the DNS server returns an Internet Protocol (IP) address corresponding to the domain name, and the terminal device can access the domain name through the IP address.
  • IP Internet Protocol
  • Mobile edge computing is a technology based on the fifth generation (5rd generation, 5G) evolution architecture that deeply integrates access networks and Internet services. It deploys application server (AS) and mobile broadband (mobile broadband, MBB) core network service processing and resource scheduling functions together to the network edge close to the access network, and provides reliable, The ultimate service experience with ultra-low latency.
  • AS application server
  • MBB mobile broadband
  • the terminal device sends a domain name resolution request (DNS query request) to the DNS server through a user plane funtion (UPF) network element connected to the MEC platform.
  • DNS query request domain name resolution request
  • UPF user plane funtion
  • This application provides a method and communication device for querying a domain name system.
  • the core network element When a terminal device performs a domain name query, the core network element combines the location information of the terminal device and the queried domain name to determine the IP address of the corresponding application server.
  • the IP address of the application server corresponds to the location of the terminal device and the queried domain name.
  • the terminal device can obtain the IP address of the application server closest to its own location and access services nearby, thereby improving the efficiency of the terminal device accessing services. The time delay for the terminal device to access the service is reduced, and the communication efficiency is improved.
  • a method for querying a domain name system is provided.
  • the execution subject of the method may be the first network element or the chip applied to the first network element.
  • the first network element may be a user plane function network element or a session management network element.
  • the method includes: the first network element receives a domain name system DNS query request from a terminal device, the DNS query request includes a first domain name, and the DNS query request is used to request the first The Internet Protocol IP address corresponding to the domain name; the first network element sends first request information to the second network element, the first request information includes the location information of the terminal device and the first domain name; the first network element receives the first The first response information sent by the second network element in response to the first request information, where the first response information includes the IP address; and the first network element sends the IP address to the terminal device.
  • the first network element adds the location information of the terminal device to the DNS query request and sends the second network element, and the second network element determines the relationship between the location information of the terminal device and the requested domain name.
  • the location of the terminal device and the requested domain name both correspond to the IP address of the application server, and the IP address is fed back to the terminal device.
  • the terminal device can access the service nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the DNS query request further includes a destination address
  • the destination address is an address of a DNS server
  • the first request information further includes: the destination address
  • the first network element is a user plane function network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the method further includes: the first network element sends first notification information to the session management network element, where the first notification information is used by the session management network element to select the first offload node or the first protocol data unit session anchor for the terminal device Point PSA, or, the first notification information is used for the session management network element to determine the location information of the terminal device.
  • the first notification information includes one or more of the first domain name, the IP address corresponding to the first domain name, and the destination address (the address of the DNS server).
  • the accuracy of the notification information sent by the user plane function network element to the session management network element is improved. Prevent the waste of communication resources and improve the efficiency of communication
  • the first network element is a session management network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the The method further includes: the first network element selects a first offload node or a first protocol data unit session for the terminal device according to any one of the first domain name, the destination address, and the IP address corresponding to the first domain name Anchor PSA, the destination address is the address of the DNS server.
  • the shunt node and PSA are inserted.
  • the terminal device can then access the application server corresponding to the first domain name through the PSA.
  • the data transmission route can be optimized, the data transmission delay can be reduced, and the data transmission efficiency can be improved.
  • the first network element is a user plane function network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the method further includes: the first network element receives the location information of the terminal device sent by the session management network element.
  • the complexity of acquiring the location information of the terminal device by the first network element can be reduced, which is easy to implement, and the accuracy of the acquired location information of the terminal device is improved.
  • the method further includes: the first network element receiving a first rule sent by the session management network element, wherein the first domain name, the destination address, and the first domain name correspond to Any one of the IP addresses meets the first rule, and the destination address is the address of the DNS server.
  • the accuracy of the user plane function network element sending notification information to the session management network element is improved, the time delay for the user plane function network element to notify the session management network element is reduced, and signaling overhead can be reduced. Improve resource utilization.
  • the location information of the terminal device includes the tracking area identifier TAI of the terminal device, the data network access identifier DNAI, the identification information of the fourth network element or the first IP address. At least one.
  • DNAI is used to identify the location of the application server corresponding to the first domain name
  • the data network access identifier DNAI is used to identify the location of the management platform where the application server corresponding to the first domain name is located.
  • the fourth network element includes a user plane function network element or a wireless access network network element, and the user plane function network element is a user plane function network element connected to the management platform where the application server corresponding to the first domain name is located.
  • the user plane function network element can access the management platform where the application server corresponding to the first domain name is located.
  • the radio access network element is the radio access network element currently accessed by the terminal device.
  • the first IP address points to the management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device.
  • the accuracy of the location information of the terminal device can be improved, so that the location information more accurately reflects the actual location of the terminal device.
  • a method for querying a domain name system is provided.
  • the execution subject of the method can be either a third network element or a chip applied to the third network element.
  • the first network element may be any one of a policy control function network element, an application function network element, a session management network element, or a DNS server.
  • the method includes: the third network element receives the first domain name and the location information of the terminal device, and the third network element determines at least according to the first domain name and the location information of the terminal device An IP address corresponding to the first domain name, the IP address corresponding to the location of the terminal device,
  • the third network element determines the IP address of the application server corresponding to the location of the terminal device and the requested domain name according to the location of the terminal device and the requested domain name, and feeds back the IP address To the terminal device.
  • the terminal device can access services nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the third network element determines the IP address corresponding to the first domain name at least according to the first domain name and location information of the terminal device, including: the third network element
  • the IP address is determined according to the first domain name, location information of the terminal device, and first information, where the first information includes: at least one domain name, a deployment location of an application corresponding to each of the at least one domain name, The IP address corresponding to the deployment location of the application.
  • the first information may also include the correspondence between the first IP address and the deployment location of the MEC platform or the deployment location of the application server.
  • the at least one domain name includes the first domain name; the third network element sends the IP address.
  • the third network element is any one of a session management network element, a policy control function network element, an application function network element, or a DNS server, and the third network element stores the First information.
  • the third network element stores the first information, so that the third network element can quickly and accurately determine the IP address of the application server corresponding to the location of the terminal device and the requested domain name. The efficiency of determining the IP address by the third network element is improved.
  • the third network element is a DNS server
  • the method further includes: the third network element receiving the position of the terminal device sent by the policy control function network element or the application function network element information.
  • the third network element is a DNS server
  • the third network element receiving the first domain name includes: the third network element receiving the session management network element or the user plane function network element The sent second request information, where the second request information includes the first domain name.
  • the second request information further includes location information of the terminal device.
  • the location information of the terminal device includes the tracking area identifier TAI of the terminal device, the data network access identifier DNAI, the identification information of the fourth network element or the first IP address. At least one.
  • the data network access identifier DNAI is used to identify the location of the application server corresponding to the first domain name, or the data network access identifier DNAI is used to identify the location of the management platform where the application server corresponding to the first domain name is located.
  • the fourth network element includes a user plane function network element or a wireless access network network element, and the user plane function network element is a user plane function network element connected to the management platform where the application server corresponding to the first domain name is located.
  • the user plane function network element can access the management platform where the application server corresponding to the first domain name is located.
  • the radio access network element is the radio access network element currently accessed by the terminal device.
  • the first IP address points to the management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device.
  • a method for querying a domain name system includes: a session management network element receives second information from a policy control function network element or an application function network element, the second information includes at least one domain name and at least one domain name The location information of the application server corresponding to each domain name in the session management network element; the session management network element determines the location information of the application server corresponding to the first domain name according to the second information and the first domain name sent by the terminal device, and the at least one domain name includes the The first domain name.
  • the session management network element determines the location information of the application server corresponding to the first domain name according to the acquired second information and the received first domain name.
  • the session management network element or the DNS server determines the IP address of the application server corresponding to the location of the terminal device and the requested domain name according to the location information of the application server, and feeds back the IP address to the terminal device.
  • the terminal device can access services nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the method further includes: the session management network element sends the location information of the application server corresponding to the first domain name to the DNS server;
  • the location information of the application server corresponding to the first domain name is used by the DNS server to determine the IP address of the application server corresponding to the first domain name.
  • the location information of the application server corresponding to the first domain name includes DNAI or a first IP address; the first IP address points to the location of the application server corresponding to the first domain name.
  • the second information further includes the IP address of the application server corresponding to each domain name in the at least one domain name.
  • the method further includes: the session management network element determines the IP address of the application server corresponding to the first domain name according to the second information; and the session management network element sends the IP address to the terminal device.
  • a communication device in a fourth aspect, includes a unit for executing the steps in the above first aspect or any possible implementation of the first aspect.
  • a communication device which includes a unit for executing the steps in the above second aspect or any possible implementation of the second aspect.
  • a communication device which includes a unit for executing the above third aspect or any possible implementation manner of the third aspect.
  • the communication device is a communication chip
  • the communication chip may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.
  • the communication device is a communication device (for example, a terminal device or an access network device or a core network device), and the communication chip may include a transmitter for sending information or data, and for receiving information or data Receiver.
  • a communication device includes at least one processor and a memory, the at least one processor acquires a program or instruction in the memory, and the at least one processor is used to execute the program or instruction to enable the communication device Perform the method in the above first aspect or any possible implementation of the first aspect.
  • a communication device includes at least one processor and a memory, the at least one processor acquires a program or instruction in the memory, and the at least one processor is used to execute the program or instruction to make the communication device Perform the above second aspect or any possible implementation of the second aspect.
  • a communication device in a ninth aspect, includes at least one processor and a memory.
  • the at least one processor acquires a program or instruction in the memory, and the at least one processor is used to execute the program or instruction to enable the communication device Perform the above third aspect or any possible implementation of the third aspect.
  • a communication device in a tenth aspect, includes at least one processor and an interface circuit.
  • the interface circuit is used for the at least one processor to obtain a program or instruction in at least one memory, and the at least one processor is used for executing the Programs or instructions to make the communication device execute the above first aspect or any possible implementation method of the first aspect.
  • a communication device in an eleventh aspect, includes at least one processor and an interface circuit.
  • the interface circuit is used by the at least one processor to obtain a program or instruction in at least one memory, and the at least one processor is used to execute The program or instruction enables the communication device to execute the above second aspect or the method in any possible implementation manner of the second aspect.
  • a communication device in a twelfth aspect, includes at least one processor and an interface circuit.
  • the interface circuit is used for the at least one processor to obtain a program or instruction in at least one memory, and the at least one processor is used to execute The program or instruction enables the communication device to execute the above third aspect or any possible implementation method of the third aspect.
  • a processor including an input circuit, an output circuit, and a processing circuit.
  • the processing circuit is configured to receive a signal through the input circuit and transmit a signal through the output circuit, so that the processor executes the first aspect to the third aspect, or the implementation of any one of the first aspect to the third aspect The method in the way.
  • the foregoing processor may be a chip
  • the input circuit may be an input pin
  • the output circuit may be an output pin
  • the processing circuit may be a transistor, a gate circuit, a flip-flop, and various logic circuits.
  • the input signal received by the input circuit may be received and input by, for example, but not limited to, a receiver
  • the signal output by the output circuit may be, for example, but not limited to, output to and transmitted by the transmitter
  • the circuit can be the same circuit, which is used as an input circuit and an output circuit at different times.
  • the embodiments of the present application do not limit the specific implementation manners of the processor and various circuits.
  • a user plane function network element or a session management network element is provided.
  • the user plane function network element or session management network element includes: the communication device provided in the seventh aspect above, or the ninth aspect provides Or the communication device provided in the eleventh aspect above.
  • a policy control function network element, application function network element, session management network element or DNS server is provided.
  • the policy control function network element, application function network element, session management network element or DNS server includes: the above The communication device provided by the eighth aspect, or the communication device provided by the tenth aspect, or the communication device provided by the twelfth aspect.
  • a communication system including: the communication device provided in the seventh aspect and the communication device provided in the eighth aspect, or the communication device provided in the ninth aspect and the tenth aspect provided above Or the communication device provided in the eleventh aspect and the communication device provided in the twelfth aspect, or the network element provided in the fourteenth aspect and the network element provided in the fifteenth aspect.
  • the communication system may also include the terminal device and/or the access network device in the solution provided in the embodiment of the present application.
  • a computer program product includes a computer program.
  • the computer program product includes a computer program.
  • the computer program is executed by a processor, it is used to execute the method in the first aspect or any possible implementation of the first aspect , Or execute the method in the second aspect or any possible implementation of the second aspect, or execute the third aspect or the method in any possible implementation of the third aspect.
  • a computer-readable storage medium stores a computer program, and when the computer program is executed, it is used to execute the first aspect or any possible implementation manner of the first aspect Or execute the method in the second aspect or any possible implementation of the second aspect, or execute the third aspect or the method in any possible implementation of the third aspect.
  • the core network element when a terminal device performs a domain name query, the core network element combines the location information of the terminal device and the queried domain name to determine the IP address of the corresponding application server.
  • the IP address of the application server corresponds to the location of the terminal device and the queried domain name.
  • the terminal device can obtain the IP address of the application server closest to its own location and access services nearby, thereby improving the efficiency of the terminal device accessing services.
  • the time delay for the terminal device to access the service is reduced, and the communication efficiency is improved.
  • FIG. 1 is a schematic diagram of an example of the architecture of a wireless communication system applicable to an embodiment of the present application.
  • FIG. 2 is a schematic diagram of another example of the architecture of a wireless communication system applicable to an embodiment of the present application.
  • Fig. 3 is a schematic diagram of an example of a domain name access process of a terminal device after the initial establishment of a session is completed.
  • FIG. 4 is a schematic interaction diagram of an example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 5 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • Fig. 6 is a schematic interaction diagram of another example of a method for querying a domain name system provided by an embodiment of the present application.
  • FIG. 7 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 8 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 9 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 10 is a schematic interaction diagram of another example of a method for querying a domain name system provided by an embodiment of the present application.
  • FIG. 11 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 12 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 13 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 14 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 15 is a schematic interaction diagram of another example of a method for querying a domain name system provided by an embodiment of the present application.
  • FIG. 16 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 17 is a schematic interaction diagram of another example of a method for querying a domain name system provided by an embodiment of the present application.
  • FIG. 18 is a schematic interaction diagram of another example of a method for querying a domain name system provided by an embodiment of the present application.
  • FIG. 19 is a schematic interaction diagram of another example of a domain name system query method provided by an embodiment of the present application.
  • FIG. 20 is a schematic diagram of a communication device provided by an embodiment of the present application.
  • FIG. 21 is a schematic diagram of another example of a communication device provided by an embodiment of the present application.
  • FIG. 22 is a schematic diagram of a communication device provided by an embodiment of the present application.
  • FIG. 23 is a schematic diagram of another example of a communication device provided by an embodiment of the present application.
  • GSM Global System of Mobile Communication
  • CDMA Code Division Multiple Access
  • WCDMA Wideband Code Division Multiple Access
  • GSM Global System of Mobile Communication
  • GPRS General Packet Radio Service
  • LTE Long Term Evolution
  • FDD Frequency Division Duplex
  • TDD Time Division Duplex
  • UMTS Universal Mobile Telecommunication System
  • WiMAX Worldwide Interoperability for Microwave Access
  • 5G 5th Generation
  • 5NR New Radio
  • Fig. 1 is a schematic block diagram of a wireless communication system architecture applicable to the present application.
  • the system architecture includes a terminal device, an access network device, a management device, a gateway device, and a data network (DN).
  • the terminal device in Figure 1 can be used to connect to the access network equipment deployed by the operator through the wireless air interface, and then to the data network through the gateway equipment;
  • the access network equipment is mainly used to implement wireless physical layer functions, resource scheduling and Functions such as wireless resource management, wireless access control, and mobility management;
  • management equipment is mainly used for equipment registration, security authentication, mobility management and location management of terminal devices, and gateway equipment is mainly used to establish channels with terminal devices.
  • the data packets between the terminal device and the external data network are forwarded on this channel;
  • the data network can correspond to a variety of different service domains, such as IP multimedia subsystem (IMS), Internet (Internet), and Internet Protocol Television (IP).
  • IP multimedia subsystem (IMS) IP multimedia subsystem
  • Internet Internet
  • IPTV Internet Protocol Television
  • other operator service domains etc.
  • network devices such as servers (including servers that provide multicast services), routers, and gateways.
  • IP multicast group management protocol In IPv4, there is a network group management protocol (Internet group management protocol, IGMP) protocol, and in IPv6, there is a multicast listener discovery protocol (multicast listener discovery protocol, MLD) protocol.
  • IGMP Internet group management protocol
  • MLD multicast listener discovery protocol
  • the aforementioned terminal device may be user equipment (UE), such as a mobile phone, a computer, or a cellular phone, a cordless phone, or a conversation.
  • UE user equipment
  • Initiation protocol session initiation protocol, SIP
  • WLL wireless local loop
  • PDAs personal digital assistants
  • STB television set top boxes
  • CPE customer premise equipment
  • the above-mentioned access network equipment may be an access network (AN)/radio access network (RAN) equipment, a network composed of multiple 5G-AN/5G-RAN nodes, the 5G-AN/ 5G-RAN nodes can be: access point (AP), next-generation base station (NR nodeB, gNB), central unit (CU) and distributed unit (DU) separated form gNB, Transmission receive point (TRP), transmission point (TP) or some other access node.
  • the above management equipment may include: unified data management network element (unified data management, UDM), access and mobility management function (AMF), session management function (session management function, SMF), policy control function ( Policy control function, PCF), application function (application function, AF), etc.
  • the gateway device can include functional units such as user plane funtion (UPF), branching point (BP), and uplink classifier (UL CL). These functional units can work independently or in combination. Realize certain control functions together, such as: AMF, SMF and PCF can be combined together as a management device to complete access control and mobility management functions such as terminal device access authentication, security encryption, location registration, and users Session management functions such as establishment, release and modification of plane transmission paths, as well as the function of analyzing some slice-related data (such as congestion) and terminal device-related data.
  • UPF mainly completes functions such as routing and forwarding of user plane data, such as: responsible for data message filtering, data transmission/forwarding, rate control, and charging information generation for terminal devices.
  • the session management network element can control the data path of the protocol data unit (PDU) session, so that the PDU session and the data network are It can correspond to multiple interfaces at the same time, that is, there can be multiple session anchor points for the same PDU session.
  • the user plane funtion (UPF) that terminates these interfaces is called PDU session anchor (PSA) or anchor UPF.
  • PSA PDU session anchor
  • Each anchor point of the PDU session can also provide a different entry to the same DN.
  • one or more UPF network elements are inserted between the access network equipment and different PSAs to achieve data offloading of uplink data to different PSAs.
  • the inserted UPF network element can be a branching point (BP) or an upstream Classifier (uplink classifier, UL CL).
  • BP or UL CL can also be referred to as a split point UPF network element.
  • each functional unit can establish a connection through a next generation network (NG) interface to achieve communication, such as: a terminal device communicates with a RAN device through a new radio (NR) interface Establish an air interface connection for transmitting user plane data and control plane signaling; terminal devices can establish a control plane signaling connection with AMF through NG interface 1 (N1 for short); AN/RAN equipment such as the next generation radio access base station (NR NodeB) , GNB), can establish a user plane data connection with the tapping point UPF through NG interface 3 (abbreviated as N3); AN/RAN equipment can establish a control plane signaling connection with AMF through NG interface 2 (abbreviated as N2); tapping point UPF can pass NG interface 9 (abbreviated as N9) establishes a user plane data connection with anchor point UPF; offloading point UPF and anchor point UPF can establish control plane signaling connection with SMF through NG interface 4 (abbreviated as N4); anchor point UPF can pass
  • the terminal device can refer to the relevant description of the terminal device in Figure 1, which will not be repeated here;
  • the access network equipment can be a base station (nodeB, NB), an evolved base station (evolution nodeB) , ENB), TRP, TP, AP or some other access unit;
  • core network equipment may include: mobility management entity (MME), policy and charging rules function (PCRF) Management equipment such as serving gateway (SGW), packet data network gateway (PGW), local gateway (LGW) and other gateway equipment.
  • MME mobility management entity
  • PCRF policy and charging rules function
  • SGW serving gateway
  • PGW packet data network gateway
  • LGW local gateway
  • interfaces between network elements in this application are only exemplary, and interfaces between network elements may also have other names, and this application does not limit the names of interfaces.
  • the terminal device in the embodiments of the present application may refer to user equipment, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile equipment, user terminal, terminal, wireless communication equipment, user agent, or User device.
  • the terminal device can also be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a wireless local loop (Wireless Local Loop, WLL) station, a personal digital processing (Personal Digital Assistant, PDA), and wireless communication.
  • SIP Session Initiation Protocol
  • WLL Wireless Local Loop
  • PDA Personal Digital Assistant
  • Functional handheld devices, computing devices, or other processing devices connected to wireless modems, in-vehicle devices, wearable devices, terminal devices in the future 5G network, or future evolution of the public land mobile network (Public Land Mobile Network, PLMN) Terminal devices, etc., are not limited in this embodiment of the present application.
  • the access network equipment in the embodiments of the present application may be equipment used to communicate with terminal devices and core network equipment.
  • the access network equipment may be a Global System of Mobile Communication (GSM) system or multiple code divisions.
  • the base station (Base Transceiver Station, BTS) in the address (Code Division Multiple Access, CDMA), or the base station (NodeB, NB) in the Wideband Code Division Multiple Access (WCDMA) system, or
  • the evolutionary base station (Evolutional NodeB, eNB or eNodeB) in the LTE system can also be a wireless controller in a cloud radio access network (Cloud Radio Access Network, CRAN) scenario, or the access network device can be a relay station or an access network device.
  • Access points, in-vehicle devices, wearable devices, network devices in future 5G networks or access network devices in future evolved PLMN networks, etc., are not limited in the embodiment of the present application.
  • IP Internet Protocol
  • URL uniform resource locator
  • the DNS server is a distributed host information database that provides mapping and conversion between domain names and IP addresses.
  • the DNS server can resolve domain names into corresponding IP addresses.
  • the terminal device can access the domain name through the domain name resolution service provided by DNS.
  • the process of domain name access is as follows: Take the terminal device accessing domain name A as an example.
  • the terminal device accesses the domain name A, it queries whether the IP address of the application server corresponding to the domain name A exists in its cache. If it exists, the terminal device can directly obtain it This IP address, access the domain name A through this IP address. If it does not exist, the terminal device can send a domain name resolution request to the DNS server.
  • the domain name resolution request carries the domain name A.
  • the DNS server returns the IP address corresponding to the domain name A, and the terminal device can access the domain name A through the IP address.
  • the terminal device generates and caches a DNS cache record after obtaining the IP address corresponding to the domain name.
  • the DNS cache record is used to indicate the correspondence between the domain name and the IP address.
  • the terminal device maintains a corresponding time to live (TTL) for each cached DNS cache record.
  • TTL of the DNS cache record is the retention time of the DNS cache record in the cache of the terminal device. In this way, if the terminal device needs to access the domain name in the DNS cache record again within the TTL of a certain DNS cache record, the terminal device can directly obtain the IP address corresponding to the domain name according to the DNS cache record. If the TTL of the DNS cache record is exceeded, the terminal device needs to access the domain name again, and obtain the IP address corresponding to the domain name through the DNS server resolution.
  • the uplink classifier (ULCL) can be used to realize the existence of multiple session anchors in the same PDU session, or the Internet Protocol Version 6 (Ipv6) multi-homing (multi-homing) can be used. homing) to realize the existence of multiple session anchors for the same PDU session.
  • Ipv6 Internet Protocol Version 6
  • multi-homing multi-homing
  • UL CL is a function provided by UPF, which aims to use the flow filter provided by SMF to perform local traffic routing for certain services. Among them, the terminal device does not perceive UL CL nor participates in the addition or deletion of UL CL.
  • UL CL forwards uplink services to different PDU session anchor points based on the service detection and service forwarding rules provided by SMF (for example, UPF1 and UPF2 in Figure 1 are two different anchor points for PDU session). And aggregate the downlink data flow to the terminal device, that is, aggregate the service data flow from different PDU session anchor points (for example, UPF1 and UPF2 in FIG. 1) to the downlink to the terminal device.
  • the PDU session is called a multi-homing PDU session.
  • a multi-homing PDU session can access the DN through multiple PDU session anchor points (for example, UPF1 and UPF2 in Figure 1).
  • the user plane data branches at a common UPF and is routed to different PDU session anchor points.
  • the UPF that supports this function is called Branching Point (BP).
  • BP Branching Point
  • the branch point forwards the uplink service data flow to different PDU session anchor points, and aggregates the downlink service data flow to the terminal device.
  • Multi-homing is only applicable to IPv6 type PDU sessions, and the PDU session can be associated with multiple IPv6 prefixes .
  • the insertion of ULCL/BP can be performed during the initial establishment of the PDU session, or at any time after the initial establishment of the PDU session. If the ULCL/BP is not inserted during the initial establishment of the PDU session of the terminal device, there is only one session anchor point PSA when the PDU session is initially established.
  • This PSA can be called a remote PSA, as shown in Figure 2 and Figure 2 Is a schematic block diagram of a wireless communication system architecture with only a remote PSA. The difference from Figure 1 is that there is only one UPF in the gateway device as a session anchor point for communication between the terminal device and the data network.
  • FIG. 3 is a schematic diagram of the domain name access process of the terminal device after the initial establishment of the session is completed.
  • the core network allocates IP-3 to the terminal device during the initial establishment of the PDU session, when the terminal device requests DNS to query the domain name A through the remote PSA, the remote PSA queries the terminal device’s DNS The request (query) is sent to the DNS server.
  • the application server corresponding to domain name A is deployed on two different MEC platforms, namely MEC platform-1 and MEC platform-2.
  • the IP addresses of the two application servers are IP-3A and IP-1.
  • the application server whose address is IP-3A is deployed on MEC platform-1, and the deployment location of MEC platform-1 is closest to the remote PSA.
  • the application server with the address IP-1 is deployed on the MEC platform-2, and the deployment location of the MEC platform-2 is closest to the current location of the terminal device.
  • the DNS service Since the DNS server does not perceive the current location of the terminal device, the DNS service receives the DNS query request from the terminal device from the remote PSA, according to the address affinity, and returns the "closest" application server to the remote PSA according to the requested domain name A Therefore, the DNS server returns the address of the application server deployed on the MEC platform-1 (IP-3A in Figure 3), so that the terminal device cannot obtain the nearest MEC platform-2 deployed on the terminal device
  • IP address of the application server prevents the terminal device from accessing nearby services through the application server deployed on the MEC platform-2, so that certain services of the terminal device are restricted or cannot access some services.
  • the terminal device can only access the service through the remote application server, the time delay for the terminal device to access the service is increased, and the communication efficiency is reduced.
  • this application provides a domain name system query method.
  • the core network element When a terminal device performs a domain name query, the core network element combines the location information of the terminal device and the queried domain name to determine the IP address of the corresponding application server.
  • the IP address of the application server corresponds to the location of the terminal device and the queried domain name.
  • the terminal device can obtain the IP address of the application server closest to its own location and access services nearby, thereby improving the efficiency of the terminal device accessing services. The time delay for the terminal device to access the service is reduced, and the communication efficiency is improved.
  • FIG. 4 is a schematic flowchart of a domain name system query method 200 according to an embodiment of this application.
  • the method provided in this application is described with the first network element and the second network element as the execution subject.
  • the execution subject of the execution method may also be a chip applied to the first network element and the second network element.
  • the method 200 may be applied in the scenarios shown in FIG. 1 and FIG. 2, and of course may also be applied in other communication scenarios, and the embodiment of the present application does not limit it here.
  • the method 200 shown in FIG. 4 may include S210 to S250.
  • S210 to S250 For the explanation of the technical features in the embodiment of FIG. 4, reference may also be made to relevant parts of other embodiments in the specification of this application. The steps in the method 200 are described in detail below in conjunction with FIG. 4.
  • the first network element receives a domain name system DNS query request from the terminal device, where the DNS query request includes a first domain name, and the DNS query request is used to request an Internet Protocol IP address corresponding to the first domain name.
  • the DNS query request further includes a destination address, and the destination address may be the address of the DNS server.
  • the first domain name can be a fully qualified domain name (FQDN). For example, if the hostname of a machine is www and the domain suffix (domain) is test.com, then the domain name FQDN of the host should be www.test.com .
  • the first domain name can also be another form of domain name, which is not limited in this application.
  • the first network element sends first request information to the second network element, where the first request information includes location information of the terminal device and the first domain name.
  • the first request information further includes the destination address.
  • the type of the first request information may be a DNS query request message including the location information of the terminal device and the first domain name.
  • the second network element determines an Internet Protocol IP address corresponding to the first domain name and the location of the terminal device according to the first request information.
  • the second network element sends to the first network element first response information in response to the first request information, where the first response information includes the IP address of the application server corresponding to the first domain name, and the IP address of the application server is The location of the terminal device corresponds, that is, the IP address is the IP address of the local application server that the terminal device can currently access.
  • the first network element receives the first response information.
  • the type of the first response information may be a DNS response message including the IP address of the application server.
  • S250 The first network element sends the IP address to the terminal device.
  • the terminal device when the terminal device needs to perform a DNS query, it will send a DNS query request (also called a DNS message) to the core network device.
  • the DNS query request includes the first domain name that the terminal device needs to query.
  • the DNS query request is used to request the IP address corresponding to the first domain name.
  • the IP address corresponding to the first domain name can be understood as the IP address of the application (application) corresponding to the first domain name, and the IP address of the application (application) can be understood as the IP address of the application server or the IP address of the application instance.
  • the terminal device may send the DNS query request to the first network element in the core network through the access network device, and the first network element may be a user plane function network element (for example, it may be an anchor user plane function network element PSA) Or it is a session management network element (for example, SMF).
  • the core network device may be the first network element. If the first network element is a session management network element, the terminal device may first send the DNS query request to the user plane function network element, and the user plane function network element may forward the DNS query request to the session management network element.
  • the user plane function network element here can be understood as an anchor point user plane function network element PSA. For example, in the architecture diagram shown in FIG.
  • the DNS query request further includes a destination address, and the destination address is the address of the DNS server (for example, an IP address, etc.). That is, the terminal device needs to finally send the DNS query request to the DNS server.
  • the first network element after receiving the DNS query request, obtains the location information of the terminal device, and adds the location information of the terminal device to the DNS query request. Further, the first network element may send first request information to the second network element, where the first request information includes location information of the terminal device and the first domain name.
  • the second network element may be any one of a session management network element (for example, SMF), a policy control function network element (for example, PCF), an application function network element (for example, AF), or a DNS server.
  • the first request information further includes the destination address.
  • the type of the first request information may be a DNS query request message including the location information of the terminal device and the first domain name.
  • the second network element may be any one of a session management network element, a policy control function network element, an application function network element, or a DNS server.
  • acquiring the location information of the terminal by the first network element may be that the first network element acquires the location information of the terminal from the session management network element or other network elements, which is not limited in this application.
  • the second network element may be any of a policy control function network element, an application function network element, or a DNS server.
  • the first network element obtains the terminal
  • the location information may be that the first network element obtains the location information of the terminal from the mobility management network element or other network elements, which is not limited in this application.
  • the specific implementation method for the first network element to add the location information of the terminal device to the DNS query request may be that the first network element can add the location information of the terminal device to the DNS query request (DNS message) option.
  • DNS message DNS message
  • the first network element can also add the location information of the terminal device in the TCP option (option), which is not limited in this application.
  • the location information of the terminal device can be sent in a separate message or included in other messages.
  • the first network element may also send the position information of the terminal device to the DNS server (server) after sending the DNS query request message to the DNS server (server), in other words, the first network element A network element can send the DNS query request message and the location information of the terminal device to the DNS server in multiple messages, which is not limited in this application.
  • the location information of the terminal device may include: the tracking area identity (TAI) of the terminal device and/or the identification information of the fourth network element.
  • the identification information of the fourth network element includes the IP address of the user plane function network element (fourth network element) or the identification (identify, ID) of the user plane function network element (fourth network element).
  • the user plane function network element here refers to the UPF of the management platform where the application server corresponding to the first domain name is connected. It can be understood that the user plane function network element can access the management platform where the application server corresponding to the first domain name is located.
  • the identification information of the fourth network element may also be the IP address of the wireless access network (fourth network element) accessed by the terminal device or the ID of the wireless access network (fourth network element) accessed by the terminal device.
  • the location information of the terminal device may also include the deployment location of the MEC platform where the application server corresponding to the first domain name currently accessible by the terminal device is located, or the deployment location corresponding to the first domain name deployed on the MEC platform currently accessible by the terminal device The deployment location of the application server.
  • a network address translation network address translation
  • NAT address translation gateway
  • UPF-1 can access the DNS server
  • UPF-2 can access the MEC platform.
  • UPF-1 may be the aforementioned first network element
  • UPF-2 may be the aforementioned fourth network element.
  • the IP address of UPF-2 is a private IP address (or private IP address) before the IP address of UPF-2 is not translated by NAT. If the first network element directly sends the private IP address to the second network element (take the DNS server as an example), the DNS server does not understand the meaning of the private IP address and cannot determine the location information of the terminal device based on the private IP, that is The IP of UPF-2 can no longer be used to characterize the location information of terminal devices.
  • the location information of the terminal device added in the DNS request should be the public IP address of the UPF-2 address after NAT translation (that is, the IP address of the N6 interface after NAT translation), so that the DNS server can be based on
  • the public IP address determines the current location information of the terminal device. That is, the location information of the terminal device may further include a first IP address, the first IP address points to a management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device.
  • the MEC platform deploys an application server.
  • the application server is the application server corresponding to the first domain name used in the DNS query request.
  • UPF-2 can connect to the management platform where the application (application server) corresponding to the first domain name is located, then the first IP address can be the public IP address (or public IP address).
  • the first network element needs to send the public network IP address obtained after NAT translation of the UPF-2 (fourth network element) to the second network So that the second network element can determine the location of the terminal device according to the public network IP address. That is, the location information of the terminal device may also include an IP address pointing to the management platform where the application corresponding to the first domain name is located.
  • the second network element will determine the IP address corresponding to the first domain name and the location of the terminal device according to the first request information.
  • the first domain name can correspond to multiple application servers deployed in different locations (for example, different MEC platforms), and the deployment location of the application server can be represented by an MEC platform identifier, where the MEC platform identifier is used to uniquely identify an MEC
  • the platform for example, the MEC platform identifier may be a data network access identity (DNAI) supported by UPF network elements deployed on the MEC platform or DNAI supported by UPF network elements connected to the MEC platform.
  • DNAI data network access identity
  • the deployment location of the first application server (ie, the first DNAI) among the deployment locations of the multiple application servers corresponds to the location of the terminal device. That is, the first application server is an application server corresponding to both the location of the terminal device and the domain name requested by the terminal device. For example, the deployment location of the first application server is the closest to the current location of the terminal device, or in other words, the MEC platform where the first application server is located is the closest to the current location of the terminal device.
  • the IP address of the first application server is the IP address requested by the terminal device in S210. E.g.
  • the first domain name is assumed to be domain name A
  • the application server corresponding to domain name A is deployed on two different MEC platforms, namely MEC platform-1 (the deployment location of MEC platform-1 is represented by DNAI-1 ) And MEC platform-2 (the deployment location of MEC platform-2 is represented by DNAI-2).
  • MEC platform-1 the deployment location of MEC platform-1 is represented by DNAI-1
  • MEC platform-2 the deployment location of MEC platform-2 is represented by DNAI-2).
  • the IP addresses of the two application servers deployed on these two different MEC platforms are IP-3A and IP-1, respectively.
  • the application server with the address IP-3A is deployed on the MEC platform-1
  • the application server with the address IP-1 is deployed on the MEC platform-2
  • the current location of the terminal device is closest to the MEC platform-2 or the current terminal device
  • the deployment location of the MEC platform corresponding to the location is DNAI-2
  • the first application server is the application server whose address is IP-1.
  • the second network element determines the IP address of the application server corresponding to both the location of the terminal device and the first domain name.
  • the second network element will send the IP address of the application server to the first network element.
  • the second network element may send first response information in response to the first request information to the first network element, where the first response information includes the IP address.
  • the type of the first response information may be a DNS response message containing the IP address of the application server.
  • the first network element may send the IP address to the terminal device.
  • the user plane function network element sends the IP address of the application server to the terminal device through the access network device; if the first network element is a session management network element, the session management The network element sends the IP address of the application server to the user plane function network element.
  • the user plane function network element sends the IP address of the application server to the terminal device through the access network device.
  • the terminal device can access business and data nearby through the IP address of the application server.
  • the first network element adds the location information of the terminal device to the DNS query request and sends the second network element, and the second network element determines with the terminal device based on the location information of the terminal device and the requested domain name.
  • the location of the device and the requested domain name both correspond to the IP address of the application server, and the IP address is fed back to the terminal device.
  • the terminal device can access the service nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the second network element will determine with the first domain name according to the first request information
  • the IP address corresponding to the location of the terminal device including S231.
  • the second network element determines the IP address of the application server according to the location information of the terminal device, the first domain name, and the first information; wherein, the first information includes: at least one domain name, and The deployment location of the application server corresponding to each domain name, the IP address information of the application server deployed on the deployment location of the application server, the at least one domain name includes the first domain name, and the deployment location of different application servers is different in terminal devices .
  • the second network element may determine the IP address of the application server according to the location information of the terminal device, the first domain name, and the first information.
  • the location information of the terminal device may include at least one of the TAI and DNAI of the terminal device, the identification information of the fourth network element, or the first IP address.
  • DNAI is used to identify the location of the application server corresponding to the first domain name, or the DNAI is used to identify the location of the management platform where the application server corresponding to the first domain name is located.
  • the fourth network element includes a user plane function network element or a wireless access network network element.
  • the user plane function network element is a user plane function network element connected to the management platform where the application server corresponding to the first domain name is located, and can be understood as The user plane function network element can access the management platform where the application server corresponding to the first domain name is located.
  • the radio access network element is the radio access network element currently accessed by the terminal device.
  • the first IP address points to the management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device. It should be understood that, in the example of this application, the specific meaning corresponding to the location of the management platform and the location of the terminal device may include the following two types:
  • the management platform corresponding to the location of the terminal device may be the management platform closest to the location of the terminal device.
  • the management platform corresponding to the location of the terminal device It may be a management platform that is comprehensively determined by other factors in addition to considering the location information of the terminal device.
  • the identification information of the fourth network element includes the IP address of the user plane function network element (fourth network element) or the identification (identify, ID) of the user plane function network element (fourth network element).
  • the user plane function network element here can be the PDU session anchor point connected to the management platform or the intermediate UPF connected to the wireless access network equipment.
  • the user plane function network element here can be the UL CL or BP that accesses the management platform, or the PDU session that accesses the management platform Anchor point.
  • the identification information of the fourth network element may also be the IP address of the wireless access network (fourth network element) accessed by the terminal or the ID of the wireless access network (fourth network element) accessed by the terminal.
  • the first IP address points to the management platform where the application server corresponding to the first domain name is located.
  • the location of the management platform corresponds to the location of the terminal device.
  • the location information of the terminal device may also include the deployment location of the MEC platform (identified by DNAI) where the application server corresponding to the first domain name that the terminal device can currently access is located, or is deployed on the MEC platform that the terminal device can currently access The deployment location of the application server corresponding to the first domain name (identified by DNAI).
  • the management platform where the application server corresponding to the first domain name is located is determined according to the location of the terminal device, that is, the location of the management platform is determined according to the location of the terminal device, then
  • the DNAI that identifies the management platform, the identification information of the user plane function network element connected to the management platform, or the IP address pointing to the management platform can all be used to indicate the location information of the terminal device.
  • the location of the management platform or the location of the application server involved corresponds to the current location of the terminal device.
  • the management platform, the MEC management platform, and the MEC platform involved in this application have the same meaning or function, and can manage the multiple applications and can provide services for multiple applications.
  • the deployment location of the MEC platform or the deployment location of the application server can be determined according to the TAI of the terminal device.
  • the second network element can obtain and store the first information.
  • the first information may include: at least one domain name, a deployment location of an application server corresponding to each of the at least one domain name, and IP address information of the application server.
  • the first information may also include the correspondence between the first IP address and the deployment location of the MEC platform or the deployment location of the application server.
  • the at least one domain name includes the first domain name.
  • one domain name can correspond to multiple application servers (IP addresses of multiple application servers).
  • the second network element can uniquely determine the deployment location of the MEC platform or the deployment location of the application server according to the location information of the terminal device. On the same MEC platform or the same application server deployment location, multiple application servers or application instances corresponding to domain names can be deployed, but there is only one application server or application instance corresponding to the same domain name. Further, the second network The meta may determine the IP address of the application server corresponding to the first domain name according to the first domain name. That is, the IP address corresponding to the first domain name and the location of the terminal device is determined as described above.
  • Table 1 is an example of content included in the first information.
  • the first information includes two applications, corresponding to two domain names: domain name A and domain name B.
  • Domain name A corresponds to two application servers, assuming that the IP addresses of the two application servers are IP-3A and IP-1 respectively.
  • the two application servers are deployed in different locations, for example, on different MEC platforms. Assuming that the application server with the address IP-3A is deployed on MEC platform-1, the application server with the address IP-1 is deployed on MEC platform-2, and the location of the terminal device is closer to the MEC platform-2, or MEC Platform-2 is close to the current location of the terminal device.
  • Domain name B corresponds to an application server, indicating that the application server is deployed in only one location or on the MEC platform.
  • IP-3B which is also deployed on MEC platform-2.
  • the deployment location of the application server or the deployment location of the MEC platform where the application server is located may be characterized by a data network DN Access Identifier (DNAI), and different DNAIs represent the deployment locations of different MEC platforms or application servers. Assume that the application server deployed on MEC platform-2 is represented by DNAI2, and the application server deployed on MEC platform-1 is represented by DNAI1.
  • DNAI data network DN Access Identifier
  • the DNS query request carries the domain name A that the terminal device needs to query. It is assumed that the location of the terminal device is closer to the MEC platform-2.
  • the first request information sent by the first network element to the second network element includes the domain name A and the location information of the terminal device.
  • the second network element determines that the IP addresses of the corresponding application servers are IP-3A deployed on the MEC platform-1 and IP-1 deployed on the MEC platform-2.
  • the two application servers correspond to different DNAIs.
  • the second network element further determines the deployment location of the MEC platform or the application server deployment location currently accessible by the terminal device according to the location information of the terminal device, that is, determines that the DNAI corresponding to the current location of the terminal device is DNAI2 (ie MEC platform-2) . In this way, it can be determined that the IP address of the application server corresponding to the location of the terminal device and the requested domain name is IP-1. Thus, IP-1 is fed back to the terminal device.
  • the first information may also include more domain names.
  • There may be more deployment locations of application servers corresponding to a certain domain name for example, there may be more deployment locations of the MEC platform.
  • a certain deployment location can also deploy more application servers corresponding to different domain names.
  • other parameters can also be used to characterize it.
  • the embodiments of the application are not limited here.
  • the second network element determines the IP address of the application server corresponding to the location of the terminal device and the requested domain name according to the location information of the terminal device, the domain name requested by the terminal device, and the first information mentioned above. .
  • the determined IP address of the application server can be made more accurate, and the efficiency of determining the application server can be improved.
  • the user plane function network element may request the session management network element for the location information of the terminal device before sending the first request information, and The location information of the terminal device is added to the first request information and sent to the second network element.
  • the session management network element can obtain the location information of the terminal device by itself, and add the location information of the terminal device to the first request information.
  • the first request information sent by the first network element to the second network element may not include the location information of the terminal device.
  • the second network element can obtain the location information of the terminal device by itself.
  • the management network element can obtain the location information of the terminal device by itself.
  • the session management network element may obtain the TAI of the terminal device from the AMF.
  • the session management network element can also subscribe to the AMF for the TAI of the terminal device, so that when the location of the terminal device moves, the AMF can provide the session management network element with the latest TAI where the terminal device is currently located, so that the session management network element can be based on
  • the TAI of the terminal device determines the location information of the terminal device.
  • the DNS server may receive the location information of the terminal device sent by the application function network element (for example, AF).
  • the application function network element may obtain the location information of the terminal device from the core network device through the capability opening information.
  • the second network element can obtain and store the first information.
  • the session management network element may receive the first information sent by a policy control function network element (for example, PCF) or an application function network element (for example, AF).
  • the application function network element may store the first information in the UDR
  • the policy control function network element may request the first information from the UDR and store the first information.
  • the session management network element may request the first information from the policy control function network element and store the first information.
  • the DNS server may receive the first information sent by an application function network element (for example, AF).
  • the first information may also be pre-configured in the DNS server. It should be understood that the manner in which the second network element obtains the first information in the embodiment of the present application is not limited.
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server, as shown in the figure 6 is an example. Based on the method steps shown in FIG. 4, the method includes S241.
  • the first network element selects the first offload node and the first protocol data unit session anchor PSA for the terminal device according to the first domain name or the IP address corresponding to the first domain name.
  • the first network element is a session management network element (for example, SMF)
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server.
  • the first network element may select the first shunt node and the second branch node for the terminal device according to the first domain name requested by the terminal device, or the IP address of the application server corresponding to the first domain name fed back by the second network element.
  • a protocol data unit session anchor PSA After inserting the shunt node and PSA. The terminal device can then access the application server corresponding to the first domain name through the PSA.
  • the data transmission route can be optimized, the data transmission delay can be reduced, and the data transmission efficiency can be improved.
  • the session management network element may execute S241 after the above step S210, that is, when receiving a domain name system DNS query request from the terminal device, determine according to the first domain name included in the DNS query request Select the first offload node and the first PSA for the terminal device.
  • the method for the SMF network element to determine the first domain name may be: the domain name list can be pre-configured on the SMF network element, or the SMF network element receives a policy message from the PCF network element.
  • the policy message contains a list of domain names, and the domain name list contains one or more As long as the domain name included in the DNS query request received by the SMF network element belongs to the domain name list, the SMF network element determines that the domain name included in the DNS query request is the first domain name.
  • the session management network element may select the first offload node for the terminal device based on the first domain name
  • the first protocol data unit session anchor point PSA, the first offload node may be the aforementioned ULCL or BP, and the first PSA may be a UPF.
  • the DNS query request may also include a destination address, and the destination address may be the address of the DNS server.
  • the SMF may also determine to select the first offload node and the first PSA for the terminal device according to the destination address included in the DNS query request, where the destination address may be the address of the DNS server.
  • the SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location
  • the SMF determines to select the first shunt node and the first PSA for the terminal device.
  • the terminal device can access the nearest service through the PSA, optimize the data transmission route, and reduce the data transmission delay.
  • SMF does not need to wait for the second network element to send the response information before inserting ULCL or BP, which can reduce signaling overhead.
  • the session management network element can select the first offload node and the first protocol data unit session anchor PSA for the terminal device according to the IP address of the application server fed back by the second network element in S240.
  • S241 can be executed after S240, that is, after receiving the first response information fed back by the second network element, select the first shunt node and the first offload node for the terminal device according to the IP address in the first response information.
  • Protocol data unit session anchor PSA can be executed after S240, that is, after receiving the first response information fed back by the second network element, select the first shunt node and the first offload node for the terminal device according to the IP address in the first response information.
  • the method for the SMF network element to select the first offload node and the first protocol data unit session anchor point PSA for the terminal device according to the IP address of the application server may be: the SMF network element may pre-configure an IP address list in advance, or SMF The network element receives a policy message from the PCF network element.
  • the policy information includes an IP address list.
  • the IP address list includes one or more IP addresses. As long as the IP address of the application server fed back by the second network element belongs to the IP address list, then the SMF The network element selects the first offload node and the first protocol data unit session anchor PSA for the terminal device based on the IP address.
  • the session management network element can be based on The IP address selects the first offload node and the first protocol data unit session anchor PSA for the terminal device.
  • the first offload node may be a ULCL or BP.
  • the accuracy of the inserted first offload node and the first PSA can be improved, and unnecessary
  • the domain name and the application deployment location that has been inserted into the offload node and PSA are inserted again into the offload node and PSA, which prevents the waste of communication resources and improves the efficiency of communication.
  • the IP address carried in the first response information fed back by the second network element is the IP address of the application server deployed on the MEC platform-2 and corresponding to the first domain name (IP-1 ).
  • IP-1 IP address of the application server deployed on the MEC platform-2 and corresponding to the first domain name (IP-1 ).
  • the session management network element selects the first offload node and inserts the first PSA.
  • the deployment location of the first PSA may be close to the deployment location of the first application server (MEC platform-2), or the first PSA may be deployed on the MEC platform-2.
  • the session management network element can insert the first PSA (UPF) in the manner of ULCL or BP. After inserting the first PSA.
  • the terminal device can access the first application server through the newly inserted first PSA.
  • the route of data transmission is: The data transmission route can be optimized, the data transmission delay can be reduced, and the data transmission efficiency can be improved.
  • the first network element is a user plane function network element
  • the second network element is a policy control function network element, a session management network element, an application function network element, or
  • the method includes S242.
  • the first network element sends first notification information to the session management network element, where the first notification information includes at least one of the first domain name, the destination address, and an IP address corresponding to the first domain name, and The first notification information is used by the session management network element to select the first offload node and the first protocol data unit session anchor PSA for the terminal device.
  • the second network element is any one of a policy control function network element, a session management network element, an application function network element, or a DNS server.
  • the first network element may send first notification information to the session management network element.
  • the first notification information includes the first domain name, the IP address corresponding to the first domain name, and the destination address (the address of the DNS server). ) One or more of them.
  • the first notification information is used by the session management network element to select the first offload node and the first protocol data unit session anchor PSA for the terminal device.
  • a possible implementation manner is: the user plane function network element sends the first notification information to the session management network according to the first domain name requested by the terminal device or according to the destination address included in the DNS query request.
  • S242 can be executed after S210, that is, only step S210 is required. After receiving the domain name system DNS query request from the terminal device, the first domain name or purpose included in the DNS query request Address, sending first notification information to the session management network element, used to notify the session management network element to select the first offload node and the first PSA for the terminal device.
  • the method for the user plane function network element to determine to send the first notification information to the session management network element may be: before the user plane function network element sends the first notification information to the session management function network element, the user plane function network element may be pre-configured in advance The first rule, or the user plane function network element receives the first rule from the session management network element, and when the first domain name or the destination address meets the first rule, the user plane function network element sends the first notification information to the session management network element.
  • the first rule includes a destination address list, and the destination address list contains one or more destination addresses.
  • the first rule is that the destination address contained in the DNS query request received by the user plane function network element is included in the destination address list. If the first rule is met, the user plane function network element determines to send the first notification information to the session management network element. In other words, if the user plane function network element determines that the destination address contained in the DNS query request satisfies the conditions for sending the first notification information to the session management network element, then the user plane function network element sends the first notification to the session management network Information, where the condition may be that the destination address included in the DNS query request is any destination address included in the first rule.
  • the first rule includes a domain name list
  • the domain name list includes one or more domain names
  • the first rule is that the domain name included in the DNS query request received by the user plane function network element is included in the domain name list.
  • the user plane function network element determines that the domain name included in the DNS query request is the first domain name.
  • the user plane function network element determines that the first domain name contained in the DNS query request satisfies the conditions for sending the first notification information to the session management network element, then the user plane function network element sends the first notification information to the session management network element.
  • Notification information where the condition may be that the first domain name included in the DNS query request is any domain name included in the first rule.
  • the user plane function network element can directly send the first notification information to the session management network element without waiting for the second network element
  • the first notification information is sent to the session management network element, which reduces the time delay for the user plane function network element to notify the session management network element and can reduce signaling overhead. Improve resource utilization.
  • the user plane function network element may send the first notification information to the session management network according to the IP address of the application server fed back by the second network element in S240.
  • the method for the user plane function network element to determine to send the first notification information to the session management network may be: the user plane function network element may pre-configure the first rule in advance, or the user plane function network element receives the first rule from the session management network element, when When the IP address of the application server meets the first rule, that is, the IP address is included in the address list, the user plane function network element sends the first notification information to the session management network element.
  • the first rule may also include an IP address list.
  • the IP address list includes one or more IP addresses.
  • the user plane function network element As long as the IP address of the application server fed back by the second network element belongs to the IP address list, the user plane function network element This IP address sends the first notification information to the session management network. In other words, if the user plane function network element determines that the IP address of the application server fed back by the second network element satisfies the condition for sending the first notification information to the session management network element, then the user plane function network element sends to the session management network
  • the first notification information where the condition may be that the IP address of the application server is any IP address included in the first rule.
  • S242 can be executed after S240, that is, steps S210, S220, S230, and S240 need to be executed.
  • the session management network element After receiving the first response information fed back by the second network element, according to the IP address in the first response information, send the first notification information to the session management network element to notify the session management network element to select the first offload for the terminal device Node and first PSA.
  • the IP address included in the first response message is the IP address (IP-1) of the application server deployed on the MEC platform-2 and corresponding to the first domain name
  • the user plane function network element The session management network element sends first notification information, and the first notification information includes the IP address.
  • the accuracy of the notification information sent by the user plane function network element to the session management network element can be improved. Prevent the waste of communication resources and improve the efficiency of communication.
  • the session management network element may select the first offload node and the first PSA for the terminal device according to the foregoing first notification information. For specific description, refer to the foregoing description of S241. For brevity, details are not repeated here.
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server.
  • Fig. 8 is an example. Based on the method steps shown in Fig. 4, the method includes S219.
  • the first network element receives the location information of the terminal device sent by the session management network element.
  • the user plane function network element may first obtain the location information of the terminal device from the session management network element before the aforementioned S220.
  • the user plane function network element may receive the location information of the terminal device sent by the session management network element (for example, SMF). Therefore, the location information of the terminal device can be added to the above-mentioned first request information and sent to the second network element, which reduces the complexity of obtaining the location information of the terminal device by the first network element, is easy to implement, and improves the performance of the acquired terminal device. The accuracy of location information.
  • the first network element adds the location information of the terminal device to the DNS query request and sends the second network element.
  • the second network element determines the IP address of the application server corresponding to the location and domain name of the terminal device and feeds it back to the terminal device.
  • the terminal device can access services nearby through the application server. Improve the quality of terminal device access services.
  • the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • FIG. 9 is a schematic flowchart of a method 300 for querying a domain name system according to another embodiment of the present application.
  • the method 300 can be applied in the scenarios shown in Figs. 1 and 2, and of course, can also be applied in other communication scenarios.
  • the embodiments are not limited here.
  • the method 300 shown in FIG. 9 may include S310 to S330.
  • the steps in the method 300 are described in detail below with reference to FIG. 9.
  • the third network element receives the first domain name and the location information of the terminal device.
  • the third network element determines an IP address corresponding to the first domain name at least according to the first domain name and the location information of the terminal device, and the IP address corresponds to the location of the terminal device.
  • S330 The third network element sends the IP address.
  • the terminal device when it needs to perform a DNS query, it will send a DNS query request to the core network device.
  • the DNS query request includes the first domain name that the terminal device needs to query.
  • the terminal device may send a DNS query request to a user plane function network element (for example, a PSA) through the access network device.
  • a user plane function network element for example, a PSA
  • this user plane function network element is equivalent to a remote PSA .
  • the user plane function network element After the user plane function network element receives the DNS query request, it will send the first domain name to the third network element, which can be a policy control function network element, an application function network element, a session management network element or a DNS server Any kind of.
  • the user plane function network element may forward the DNS query request from the terminal device to the third network element, and the DNS query request is based on the first domain name included in the DNS query request.
  • the third network element receives the first domain name and the location information of the terminal device. For descriptions related to the location information of the terminal device, reference may be made to the related descriptions in S231 above. For brevity, details are not repeated here.
  • the first domain name and the location information of the terminal device may be sent by the same network element to the third network element.
  • the third network element is a DNS server
  • the location information of the first domain name and the terminal device may be a session management network element.
  • the user plane function network element sends to the DNS server.
  • the first domain name and the location information of the terminal device may be sent by different network elements to the third network element.
  • the third network element is a DNS server
  • the first domain name may be a session management network element or a user plane function network element sent to the DNS server
  • the location information of the terminal device may be sent to the DNS server by an application management network element. This application is not restricted here.
  • the third network element determines an IP address corresponding to the first domain name at least according to the first domain name and the location information of the terminal device, and the IP address corresponds to the location of the terminal device.
  • the specific process of S320 reference may be made to the above description of S231. For brevity, details are not repeated here.
  • the third network element may determine the IP address corresponding to the first domain name according to the first domain name, the location information of the terminal device, and the first information.
  • the first information includes: at least one domain name, the deployment location of the application server corresponding to each domain name in the at least one domain name (for example, the MEC platform identifier or DNAI can be used to indicate), and the application on the deployment location of the application
  • the first information may also include the correspondence between the first IP address and the deployment location of the MEC platform or the deployment location of the application server.
  • the third network element determines the IP address of the application server corresponding to both the location of the terminal device and the first domain name.
  • the third network element will send the IP address of the application server to the terminal device.
  • the session management network element may first send the IP address of the application server to the user plane function network element, and the user plane function network element uses the access network device to use the IP address of the application server. The address is sent to the terminal device.
  • the user plane function network element may send the first notification information to the session management network according to the IP address of the application server fed back by the third network element, for informing the session management network element to select the first offload node and the second offload node for the terminal device.
  • One PSA For the method for the user plane function network element to determine to send the first notification information to the session management network, reference may be made to the description of S242 above. For brevity, details are not repeated here.
  • the DNS server can first send the IP address of the application server to the user plane function network element or the session management network element, and access through the user plane function network element or the session management network element
  • the network equipment sends the IP address of the application server to the terminal device.
  • the session management network element may select the first offload node and the first protocol data unit session anchor PSA for the terminal device according to the IP address of the application server fed back by the third network element.
  • the specific method may refer to the above-mentioned S241 Description, for the sake of brevity, I will not repeat it here. This application does not limit the specific process of sending the IP address of the application server to the terminal device in the third network element.
  • the third network element determines the IP address of the application server corresponding to the location of the terminal device and the requested domain name according to the location of the terminal device and the requested domain name, and feeds back the IP address To the terminal device.
  • the terminal device can access services nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the third network element may be any one of a session management network element, a policy control function network element, an application function network element, or a DNS server, and the third network element stores the first network element. information.
  • the third network element may obtain and store the first information.
  • the session management network element may receive the first information sent by a policy control function network element (for example, PCF) or an application function network element (for example, AF).
  • the application function network element may store the first information in the UDR.
  • the policy control function network element may request the first information from the UDR and store the first information.
  • the DNS server may receive the first information sent by an application function network element (for example, AF).
  • the first information may also be pre-configured in the DNS server. It should be understood that the manner in which the third network element obtains the first information in the embodiment of the present application is not limited.
  • the session management network element selects the first offload for the terminal device according to the first domain name or the IP address corresponding to the first domain name Node and first PSA.
  • the session management network element-offload node and the first PSA For the process of the session management network element-offload node and the first PSA, reference may be made to the related description in S241 above. For brevity, details are not repeated here.
  • the DNS server may obtain the location information of the terminal device in the following manner:
  • the DNS server receives the location information of the terminal device sent by the policy control function network element, the application function network element or the session management network element.
  • the session management network element may obtain the location information of the terminal device from the AMF.
  • the session management network element can also subscribe to the AMF for the location information of the terminal device, so that when the location of the terminal device moves, the AMF can provide the session management network element with the latest location information where the terminal device is currently located.
  • the application function network element can obtain the location information of the terminal device from the core network device through the network exposure function (NEF).
  • the policy control function network element can obtain the location information of the terminal device from the AMF.
  • the policy control function network element, the application function network element, or the session management network element may send the location information of the terminal device to the DNS server.
  • the DNS server may obtain the location of the terminal device from the policy control function network element, the session management network element or the application function network element, and further determine the deployment location of the MEC platform currently accessible by the terminal device according to the location of the terminal device Or the deployment location of the application server.
  • the DNS server may directly obtain the deployment location of the MEC platform or the deployment location of the application server that the terminal device can currently access from the policy control function network element, the session management network element, or the application function network element.
  • the position information of the terminal device sent by the policy control function network element, the application function network element or the session management network element is received by the DNS server, so that the position information of the terminal device acquired by the DNS server can be more accurate. Further improve the accuracy and efficiency of the DNS server in determining the IP address corresponding to the location of the terminal device and the first domain name.
  • step S310 if the third network element is a DNS server, the DNS server may obtain the first domain name of the terminal device in the following manner:
  • the third network element receives second request information sent by the session management network element or the user plane function network element, where the second request information includes the first domain name.
  • the terminal device when it needs to perform a DNS query, it will send a DNS query request to the core network device.
  • the DNS query request includes the first domain name that the terminal device needs to query.
  • the DNS query request further includes a destination address.
  • the destination address may be the address of the DNS server.
  • the DNS query request is used to request the IP address corresponding to the first domain name.
  • the terminal device may send the DNS query request to the user plane function network element in the core network through the access network device, and the user plane function network element may directly send the second request information to the DNS server according to the DNS query request.
  • the request information includes the first domain name.
  • the user plane function network element may send the first notification information to the session management network according to the first domain name or the destination address in the DNS query request, for notifying the session management network element to select the first offload node and the second offending node for the terminal device.
  • One PSA For the method for the user plane function network element to determine to send the first notification information to the session management network, reference may be made to the description of S242 above. For brevity, details are not repeated here.
  • the user plane function network element may first send the DNS query request to the session management network element, and the session management network element will send the second request information to the DNS server according to the DNS query request, and the second request information includes the first request information. domain name.
  • the session management network element may select the first offload node and the first protocol data unit session anchor PSA for the terminal device according to the first domain name or the destination address in the DNS query request.
  • the specific method may refer to the above-mentioned S241 Description, for the sake of brevity, I will not repeat it here.
  • the aforementioned second request information may also include location information of the terminal device.
  • the user plane function network element may request the session management network element for the location information of the terminal device or the user before sending the second request information.
  • the plane function network element has obtained the location information of the terminal device in advance.
  • the session management network element sends the location information of the terminal device to the user plane function network element.
  • the user plane function network element adds the location information of the terminal device to the second request information and sends it to the DNS server.
  • the session management network element first obtains the location information of the terminal device, adds the location information of the terminal device to the second request information and sends it to the DNS server.
  • the above-mentioned specific implementation method of adding the location information of the terminal device to the DNS query request may be to add the location information of the terminal device to the DNS query request (DNS message) option.
  • TCP can carry DNS messages, it can also add location information of the terminal device to the TCP options, which is not limited in this application.
  • FIG. 10 is a schematic flowchart of a method 400 for querying a domain name system according to an embodiment of the present application.
  • the method 400 may be applied in the architecture shown in FIG. 1.
  • the process shown in Figure 10 mainly describes the process of the session management network element determining the IP address of the application server. This includes the process of the session management network element determining the IP address of the application server by itself and the process of determining the IP address of the application server through the policy control function network element or the application function network element.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the application function network element takes AF as an example.
  • the method 400 includes:
  • the AF uses the network exposure function (network exposure function) to determine the corresponding relationship between the deployment location of the application server (for example, the MEC platform identifier or DNAI), the domain name and the IP address of the application server (that is, the above-mentioned first information) , NEF)
  • the network element is stored in the UDR.
  • the first information can also be stored in the DNS server.
  • the content of the first information may be the content shown in Table 1 above.
  • the terminal device initiates a PDU session establishment process. Specifically, the terminal device carries parameters such as a PDU session identifier, a single network slice selection assistance information (S-NSSAI), and a data network name (data network name, DNN) to send to the AMF.
  • the AMF selects the SMF network element according to the S-NSSAI and DNN, and sends the permanent identification of the terminal device, the location information of the terminal device, the PDU session identification, S-NSSAI and DNN to the SMF network element.
  • the location information of the terminal device in step S402 may be TAI, or the IP address of the wireless access network accessed by the terminal device or the ID of the wireless access network accessed by the terminal device.
  • S403 During the session establishment process, the SMF invokes the PCF servicing operation policy establishment control request (Npcf_SMPolicy Control_Create Request), requesting to obtain the policy information related to the PDU session from the PCF.
  • Npcf_SMPolicy Control_Create Request Policy establishment control request
  • the PCF calls the UDR service operation request (Nudr_DM_Query), and obtains information related to the application subscribed by the terminal device from the UDR, which includes the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server in S401 (That is, the first message).
  • the PCF generates a policy and charging control rule (Policy and Charging Control rule, PCC rule) for the deployment location, domain name, and IP address of the application server, and sends a control response (Npcf_SMPolicyControl_Create Response) to the SMF, SMF saves the PCC rule, which includes the deployment location of the application server contracted by the terminal device (the deployment location of the application server can be represented by DNAI), the correspondence between the domain name and the IP address of the application server.
  • Policy and Charging Control rule Policy and Charging Control rule
  • the PCC rule may also contain other rules, such as charging rules, packet forwarding rules, and which application servers (ie DNAI list) are deployed or which application servers' IP addresses (ie IP address list) or applications
  • the domain name corresponding to the server namely the domain name list
  • which destination addresses namely the address list of the DNS server
  • SMF selects UPF1 network element as the anchor point (PSA-1) of this PDU session according to parameters such as S-NSSAI and DNN, and if SMF is based on the deployment location of the application server contained in the PCC rule (the deployment location of the application server can be (Expressed by DNAI) It is determined that the terminal device has signed up for some applications deployed by the MEC platform, then SMF sends an N4 session (N4 session) establishment request message to the UPF1, and the N4 session establishment request message needs to carry forwarding rules for DNS query messages. It is used to instruct the UPF to forward the DNS query message to the SMF after receiving the DNS query message from the terminal device.
  • N4 session N4 session
  • the terminal device After the establishment of the PDU session is completed, the terminal device sends a DNS query to the core network through the access network device according to its own business requirements, and initiates a DNS query of an application.
  • the DNS query request carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • S409a The SMF detects the domain name included in the DNS query request. If the domain name is included in the application server deployment location, domain name, and IP address of the application server obtained from S405, the SMF determines the application corresponding to the domain name currently accessible to the terminal device The deployment location of the server (for example, the MEC platform identifier or DNAI can be used to indicate). Based on the deployment location of the application server, the IP address of the corresponding application server is further determined according to the domain name included in the DNS query request.
  • the deployment location of the server for example, the MEC platform identifier or DNAI can be used to indicate.
  • the specific implementation manner for SMF to determine the deployment location of the application server corresponding to the domain name currently accessible by the terminal device may be:
  • SMF can determine the domain name requested by the terminal device based on the corresponding relationship between the TAI of the terminal device obtained from the AMF in step S402, the domain name requested by the terminal device, and the deployment location, domain name and IP address of the application server obtained in step S405.
  • the deployment location of the corresponding application server for example, the MEC platform identifier or DNAI can be used to indicate).
  • the method for SMF to obtain the TAI of the terminal device can be that during the session establishment process, the SMF obtains the TAI of the terminal device from the AMF.
  • SMF can also Subscribe to the AMF for the TAI of the terminal device, so that when the terminal device moves, the AMF can provide the SMF with the latest TAI where the terminal device is currently located.
  • SMF can also determine the IP address of the user plane function network element serving the terminal device or the ID of the user plane function network element serving the terminal device according to the context information of the terminal device, and further determine the corresponding domain name requested by the terminal device
  • the deployment location of the application server for example, the MEC platform identifier or DNAI can be used to indicate).
  • the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the SMF may determine whether to perform the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element may pre-configure the domain name list according to the PCC rule received from the PCF network element in S405.
  • the PCC rule contains a domain name list, and the domain name list contains one or more domain names.
  • the domain name included in the DNS query request received by the element belongs to the domain name list, then the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI) to implement the application Local diversion of service flow reduces time delay.
  • the SMF may also determine whether to execute the ULCL/BP insertion process according to the destination address included in the DNS query request. Among them, the destination address can be understood as the address of the DNS server.
  • the SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location, the SMF determines to select the first shunt node and the first PSA for the terminal device.
  • SMF chooses to insert BP
  • SMF also needs to allocate a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • the SMF determines that the domain name requested by the terminal device is not included in the PCC rule, in other words, if the SMF cannot determine the IP address corresponding to the domain name according to the PCC rule, the SMF does not perform S409a, but performs S409b And S409c:
  • the SMF adds the location of the terminal device to the DNS query request message, and forwards the DNS query request message to a DNS server (server) to obtain the IP address of the application server corresponding to the application.
  • the location of the terminal device may be the TAI of the terminal device, or the identification of the MEC platform that the terminal device can currently access, or the DNAI that the terminal device can currently access.
  • the location of the terminal device may also be the access network identifier of the current serving terminal device.
  • the access network identifier may be RAN ID or RAN IP address.
  • the specific implementation method for the SMF to add the location information of the terminal device to the DNS query request may be: the SMF adds the location information of the terminal device to the DNS query request (DNS message) option.
  • DNS message DNS message
  • SMF can also add location information of the terminal device to the TCP option, which is not limited in this application.
  • SMF can also send the DNS query request message to the DNS server (server), and then send the location information of the terminal device to the DNS server (server), in other words, SMF can send the DNS query
  • the query request message and the location information of the terminal device are sent to the DNS server in multiple messages, which are not limited in this application.
  • the DNS server determines the IP address of the corresponding application server through the domain name requested by the DNS query, and sends it to the SMF.
  • S410 The SMF returns a DNS query response (response) to the PSA-1, which includes the IP address of the application server.
  • PSA-1 returns a DNS query response (response) to the terminal device, which includes the IP address of the application server.
  • the subsequent terminal device uses the IP address of the application server contained in the DNS query response to communicate with the application server through PSA-1.
  • the SMF may execute the ULCL/BP insertion process according to the query response.
  • an IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element in S405.
  • the PCC rule contains a list of IP addresses, and the IP address list contains one or more IP addresses.
  • the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (for example, IP-1 in Table 1) (for example, MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process. If SMF chooses to insert BP, SMF also needs to assign a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • IP-1 IP-1 in Table 1
  • MEC platform-2 for example, MEC platform-2 in Table 1
  • the IP address of the application server corresponding to the location and domain name of the terminal device is determined according to the location of the terminal device and the requested domain name, and the IP address of the application server is fed back to Terminal device.
  • the terminal device can access services nearby through the application server. Improve the quality of terminal device access services.
  • the data transmission path of the terminal device can be optimized. Reduce data transmission delay and improve data transmission efficiency.
  • FIG. 11 is a schematic flowchart of a method 500 for querying a domain name system according to an embodiment of the present application.
  • the method 400 may be applied in the architecture shown in FIG. 1.
  • the flow shown in FIG. 11 mainly describes the process of determining the IP address of the application server by the session management network element when the terminal device moves.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the application function network element takes AF as an example.
  • the method 500 includes:
  • S501 AF stores the deployment location of the application server (for example, the MEC platform identifier or DNAI), the correspondence between the domain name and the IP address of the application server (that is, the above-mentioned first information) in the UDR through the NEF network element .
  • the SMF obtains the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server through the PCF.
  • the terminal device initiates a DNS query request after the session establishment is completed, and the DNS query request includes the domain name to be queried.
  • SMF determines the deployment location of the application server corresponding to the current location of the terminal device according to the current location (location-1) information of the terminal device, and further determines the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server The IP address of the application server corresponding to the domain name queried by the terminal device. The terminal device is notified of the determined IP address of the application server.
  • the IP address of the application server corresponding to the domain name returned by the SMF is a remote application server (for example, The IP address (for example, IP-3A) of the application server deployed on the MEC platform-1 in Table 1.
  • S502 The position of the terminal device has moved. Assume that the position of the terminal device has moved from position-1 to position-2.
  • the SMF obtains the new location information (location-2) where the terminal device is currently located from the AMF.
  • the SMF can determine that the deployment location of the application server corresponding to the current location of the terminal device (for example, it can be represented by a DNAI or MEC platform identifier) has changed.
  • SMF judges that the position -1 (for example, it can be represented by TAI-1) of the terminal device corresponds to DNAI2 or MEC platform-2, and the position -2 (for example, which can be represented by TAI-2) corresponds to DNAI1 or MEC platform-1, where If DNAI1 is different from DNAI2, SMF determines that the deployment location of the application server corresponding to the current location of the terminal device has changed.
  • the SMF can trigger the terminal device to update the DNS cache so that the terminal device can obtain the latest DNS query at the current location (location-2) The IP address of the application server.
  • the SMF may send DNS cache update indication information to the terminal device through control plane signaling.
  • the SMF can directly send control plane signaling to the terminal device through the access network device, such as an N1 interface session management (session management, SM) message, which contains protocol configuration options (protocol configuration options). , PCO), where the DNS cache update indication information is included in the PCO, which is used to instruct the terminal device to initiate DNS cache update.
  • the SMF sends a user plane message to the terminal device through UPF1, and the message is used to instruct the terminal device to initiate DNS cache update.
  • the terminal device After receiving the DNS cache update instruction information, the terminal device initiates a DNS query process. Specifically, the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements, and initiates a DNS query for an application.
  • the DNS query carries the domain name corresponding to the application.
  • the DNS The query request also includes the destination address (the address of the DNS server).
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • the UPF1 After receiving the DNS query request, the UPF1 forwards the DNS query request message of the terminal device to the SMF.
  • S506 The SMF detects the domain name requested by the terminal device, and determines the deployment location of the application server according to the current location (location-2) of the terminal device, and further determines the IP address of the application server at the deployment location.
  • location-2 the current location
  • IP address the IP address of the application server at the deployment location.
  • the SMF may determine whether to execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element is based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names, as long as the SMF network element receives The domain name included in the DNS query request belongs to the domain name list, then the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select UPF2 (PSA-2) and UL CL/BP for the terminal device according to the destination address included in the DNS query request, where the destination address can be understood as the address of the DNS server.
  • SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location, then SMF determines to select UPF2 (PSA-2) and UL CL/BP for the terminal device .
  • SMF chooses to insert BP
  • SMF also needs to allocate a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • S507 The SMF returns a DNS query response (response) to the PSA-1, which includes the IP address of the application server.
  • PSA-1 returns a DNS query response to the terminal device, which includes the IP address of the application server.
  • the subsequent terminal device uses the IP address of the application server contained in the DNS query response to communicate with the application server through PSA-1.
  • the SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains an IP address list, and the IP address list contains one or more IP addresses, as long as The IP address included in the DNS query response received by the SMF network element belongs to the IP address list, and the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (for example, IP-1 in Table 1) (for example, MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • IP-1 in Table 1 for example, IP-1 in Table 1
  • MEC platform-2 in Table 1 for example, MEC platform-2 in Table 1
  • SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • S509 refer to the description of S412 above. For the sake of brevity, I won't repeat them here.
  • ULCL/BP can also be dynamically inserted according to the service access of the terminal device to realize local offloading, optimize the path of local service access, and improve communication efficiency.
  • FIG. 12 is a schematic flowchart of a method 600 for querying a domain name system according to an embodiment of the present application.
  • the method 600 may be applied to the architecture shown in FIG. 1.
  • the process shown in FIG. 12 mainly describes the process of determining the IP address of the application server corresponding to the domain name in a topology enhancement (enhancing Topology of SMF and UPF, ETSUN) scenario for the SMF network element and the UPF network element.
  • a topology enhancement enhancing Topology of SMF and UPF, ETSUN
  • the same PDU session may correspond to two SMF network elements, which are the first session management network element and the second session management network element.
  • the terminal device when the terminal device establishes a PDU session at location-1, the PDU session has a corresponding anchor user plane function network element (for example, UPF1), and the anchor user plane function network element is managed by the anchor SMF.
  • anchor user plane function network element for example, UPF1
  • the anchor user plane function network element is managed by the anchor SMF.
  • a PDU session switch occurs. After the PDU session is switched, the user plane function network element directly connected to the access network element corresponding to the PDU session exceeds the original anchor SMF service area, and It is a new anchor point, intermediate SMF (intermediate SMF, I-SMF) for management.
  • I-SMF intermediate SMF
  • the embodiments of the present application are not necessarily limited to the scenario of session switching.
  • it may also be applicable to scenarios where a PDU session corresponds to two (or more) SMF network elements.
  • FIG. 12 shows the specific process of inserting I-SMF during the establishment of the PDU session.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the application function network element takes AF as an example.
  • the method 600 includes:
  • the AF stores the deployment location of the application server (for example, it can be represented by the MEC platform identifier or DNAI), the correspondence between the domain name and the IP address of the application server (that is, the aforementioned first information) in the DNS server. Further, the first information can also be stored in the UDR. For example, the content of the first information may be the content shown in Table 1 above. For the specific process of S601, reference may be made to the description of S401 above. For brevity, details are not repeated here.
  • the terminal device initiates a PDU session establishment process. Specifically, the terminal device carries the PDU session identifier, S-NSSAI and DNN and other parameters and sends it to the AMF.
  • AMF selects SMF and I-SMF network elements according to S-NSSAI and DNN, and combines the identification of SMF network element, the permanent identification of the terminal device, the location information of the terminal device (such as TAI), the PDU session identification, S-NSSAI and DNN The other parameters are sent to the I-SMF network element.
  • the I-SMF network element selects an intermediate UPF (intermediate UPF, I-UPF) network element.
  • the I-SMF invokes a PDU session creation request (Nsmf_PDUSession_Create request), where the PDU session creation request carries a list of DNAI supported by the I-SMF and is sent to the SMF network element.
  • S605 The SMF invokes the PCF service operation policy establishment control request (Npcf_SMPolicy Control_Create Request), requesting to obtain the policy information related to the PDU session from the PCF.
  • PCF calls the UDR service operation request (Nudr_DM_Query) to obtain information related to the application contracted by the terminal device from the UDR, including the deployment location of the application server in S601, the corresponding relationship between the domain name and the IP address of the application server (ie The above first information).
  • the PCF generates a policy and charging control rule (Policy and Charging Control rule, PCC rule) for the deployment location, domain name, and IP address of the application server, and issues a control response (Npcf_SMPolicyControl_Create Response) through a service-based operation policy to SMF, SMF saves the PCC rule, which contains the corresponding relationship between the deployment location of the application server contracted by the terminal device, the domain name and the IP address of the application server.
  • Policy and Charging Control rule Policy and Charging Control rule
  • the PCC rule may also contain other rules, such as charging rules, packet forwarding rules, and which application servers (ie DNAI list) are deployed or which application servers' IP addresses (ie IP address list) or applications
  • the domain name corresponding to the server namely the domain name list
  • which destination addresses namely the address list of the DNS server
  • S607 The SMF selects the UPF1 network element as the anchor point (PSA-1) of the PDU session according to parameters such as S-NSSAI and DNN.
  • the SMF sends the deployed application information to the I-SMF based on the list of DNAI supported by the I-SMF and the deployment locations of those application servers supported by the I-SMF (for example, indicated by the MEC platform identifier or DNAI).
  • the application information includes the corresponding relationship between the deployment location of the application server, the domain name, and the IP address of the application server.
  • SMF based on the application information of the deployment location of the application server supported by I-SMF, determines the deployment location of the application server (MEC platform) that can execute ULCL/BP insertion, the IP address of the application server (ie, the IP address list), and the application server One or more of the corresponding domain name (namely domain name list) and destination address (namely DNS server address list) are sent to I-SMF.
  • the I-SMF receives the application information deployed at the deployment location of the supported application server, and sends a DNS query request forwarding rule to the I-UPF, which is used to instruct the I-UPF to receive the DNS query message from the terminal device, Forward the DNS query message to the I-SMF.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request may also include a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request can be FQDN or other forms of domain name, which is not limited in this application.
  • the I-UPF After receiving the DNS query request, the I-UPF forwards the DNS query request message of the terminal device to the I-SMF according to the instruction of the I-SMF in S609.
  • the I-SMF detects the domain name requested by the terminal device, and determines the deployment location of the application server corresponding to the requested domain name according to the TAI of the terminal device. For example, the management platform identifier or DNAI representation can be used to further determine the and The IP address of the application service corresponding to the domain name.
  • the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys the application corresponding to the domain name requested by the terminal device server.
  • the I-SMF may determine whether to perform the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • a list of domain names can be pre-configured on the I-SMF network element in advance, or the I-SMF network element may pre-configure the domain name list according to the instruction information received from the SMF network element in S608, the instruction information includes a list of domain names, and the domain name list includes one or more domain names
  • the I-SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the I-SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI). Distribute the application's service flow locally to reduce delay.
  • the I-SMF can also determine whether to select UPF2 (PSA-2) and UL CL/BP for the terminal device according to the destination address included in the DNS query request, where the destination address can be understood as the address of the DNS server .
  • I-SMF determines that the DNS server address points to a third party (such as Tencent, Ali), and the third-party application server is deployed in the current location, then I-SMF determines that UPF2 (PSA-2) and UL CL/BP.
  • the SMF if the I-SMF chooses to insert the BP, the SMF also needs to allocate a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • the I-SMF returns a DNS query response (response) to the I-UPF, which includes the determined IP address of the application server.
  • the I-UPF returns a DNS query response to the terminal device, which includes the IP address of the application server.
  • the subsequent terminal device uses the IP address of the application server contained in the DNS query response to communicate with the application server through the I-UPF.
  • the I-SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the I-SMF network element in advance, or the I-SMF network element can receive the instruction information from the SMF network element in S608 according to the instruction information.
  • the instruction information includes an IP address list, and the IP address list includes one or For multiple IP addresses, as long as the IP address contained in the DNS query response received by the I-SMF network element belongs to the IP address list, the I-SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes ULCL/ BP insert process.
  • I-SMF network element determines that the deployment location of the application server corresponding to the IP address (such as IP-1 in Table 1) (such as MEC platform-2 in Table 1) allows ULCL/BP insertion, then I-SMF Select UPF2 (PSA-2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • IP-1 in Table 1 such as MEC platform-2 in Table 1
  • FIG. 13 is a schematic flowchart of a method 600 for querying a domain name system according to another embodiment of the present application.
  • the difference from the example shown in FIG. 12 is that the example shown in FIG. 13 is after the position of the subsequent terminal device changes.
  • Figure 12 shows the insertion of I-SMF during the establishment of a PDU session.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the application function network element takes AF as an example.
  • the method 700 includes:
  • the AF stores the deployment location of the application server (for example, it can be represented by the MEC platform logo or DNAI), the corresponding relationship between the domain name and the IP address of the application server (that is, the above-mentioned first information) in the UDR through the NEF network element inside.
  • the SMF obtains the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server through the PCF.
  • the terminal device initiates a DNS query request after the session establishment is completed, and the DNS query request includes the domain name to be queried.
  • the SMF determines the DNAI corresponding to the current location of the terminal device based on the current location (location-1) information of the terminal device. Further, the IP address of the application server corresponding to the domain name queried by the terminal device is determined according to the correspondence between the deployment location of the application server, the domain name and the IP address of the application server. The terminal device is notified of the determined IP address of the application server.
  • the IP address of the application server corresponding to the domain name returned by the SMF is a remote application server (for example, The IP address (for example, IP-3A) of the application server deployed on the MEC platform-1 in Table 1.
  • the IP address for example, IP-3A
  • S702 The position of the terminal device has moved. Assume that the position of the terminal device has moved from position-1 to position-2.
  • the AMF determines that the UE has moved out of the service range of the SMF, and the AMF inserts the I-SMF.
  • the I-SMF invokes a PDU session creation request (Nsmf_PDUSession_Create request), where the PDU session creation request carries a list of DNAI supported by the I-SMF and is sent to the SMF network element.
  • the SMF sends the application information deployed by the deployment locations of those application servers supported by the I-SMF to the I-SMF according to the DNAI list supported by the I-SMF.
  • the application information includes the corresponding relationship between the deployment location of the application server, the domain name, and the IP address of the application server.
  • SMF will implement the deployment location of the application server (MEC platform) that can execute ULCL/BP insertion, the IP address of the application server (that is, the IP address list), and the application
  • One or more of the domain name (namely the domain name list) and the destination address (namely the address list of the DNS server) corresponding to the server are sent to the I-SMF.
  • the corresponding relationship between the application destination address, deployment location, domain name, and IP address is obtained by SMF from PCF during the session establishment process.
  • the I-SMF receives the application information deployed at the deployment location of the application server supported by the I-SMF, and sends an N4 session modification request message to the I-UPF, which needs to carry the DNS query message forwarding rule to indicate the I-UPF
  • the UPF forwards the DNS query message to the I-SMF.
  • the I-SMF may send DNS cache update indication information to the terminal device through control plane signaling.
  • the I-SMF can directly send an N1SM message to the terminal device through the access network device.
  • the N1SM message contains the PCO.
  • the PCO contains DNS cache update indication information, which is used to instruct the terminal device to initiate DNS. Cache update.
  • the I-SMF sends a user plane message to the terminal device through the I-UPF, and the message is used to instruct the terminal device to initiate a DNS cache update.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • S708 After receiving the DNS query request, the I-UPF forwards the DNS query request message of the terminal device to the I-SMF according to the instruction of the I-SMF in S705.
  • the I-SMF detects the domain name requested by the terminal device, and determines the deployment location of the application server corresponding to the domain name requested by the terminal device according to the current location of the terminal device (such as TAI), and further determines the deployment location corresponding to the domain name.
  • the IP address of the application service For the specific process of S709, refer to the description of S409a, or the description of S408b and S408c. For brevity, I won't repeat it here.
  • the I-SMF can execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the specific process refer to the description of S612.
  • details are not repeated here.
  • the I-SMF returns a DNS query response (response) to the I-UPF, which includes the IP address of the application server.
  • the I-UPF returns a DNS query response to the terminal device, which includes the IP address of the application server.
  • the subsequent terminal device uses the IP address of the application server contained in the DNS query response to communicate with the application server through the I-UPF.
  • the I-SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • an IP address list can be pre-configured on the I-SMF network element in advance, or the I-SMF network element can receive the instruction information from the SMF network element in S704 according to the instruction information, the instruction information includes an IP address list, and the IP address list includes one or For multiple IP addresses, as long as the IP address contained in the DNS query response received by the I-SMF network element belongs to the IP address list, the I-SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes ULCL/ BP insert process.
  • PSA-2 UPF2
  • BP UL CL/BP
  • I-SMF network element determines that the deployment location of the application server corresponding to the IP address (such as IP-1 in Table 1) (such as MEC platform-2 in Table 1) allows ULCL/BP insertion, then I-SMF Select UPF2 (PSA-2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • IP-1 in Table 1 such as MEC platform-2 in Table 1
  • the I-SMF performs the resolution of the DNS query request, which can ensure that the terminal device obtains the application's IP address at a new location, and can also dynamically insert ULCL according to business access /BP, to achieve local distribution, optimize the path of local business access, and improve communication efficiency.
  • FIG. 14 is a schematic flowchart of a method 800 for querying a domain name system according to an embodiment of the present application.
  • the method 800 may be applied to the architecture shown in FIG. 1.
  • the process shown in Figure 14 mainly describes the enhanced DNS server, so that the DNS server stores the above-mentioned information about the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server.
  • the SMF/UPF is parsing the DNS message ( After the DNS query request), the location of the terminal device is actively added to the DNS query request, and the DNS query request including the domain name queried by the terminal device and the location of the terminal device is sent to the DNS server.
  • the DNS server returns the IP address corresponding to the domain name and the location of the terminal device according to the DNS query request.
  • the SMF can also insert ULCL/BP for the terminal device according to the IP address in the DNS response message to optimize the local service access path.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the user plane function network element takes UPF as an example
  • the application function network element takes AF as an example.
  • the method 800 includes:
  • the DNS server stores the deployment location of the application server (for example, it can be represented by the MEC platform identifier or DNAI), the correspondence between the domain name and the IP address of the application server (that is, the aforementioned first information).
  • the method for the DNS server to obtain the deployment location of the application server can be as follows: the AF determines the deployment location of the application server (for example, it can be represented by the MEC platform logo or DNAI), the correspondence between the domain name and the IP address of the application server (ie The above-mentioned first information) is stored in the DNS server. Further, the AF may also store the first information in the UDR through the NEF network element. For the specific description of this process, reference may be made to the description of S401 above. For brevity, details are not repeated here.
  • the terminal device initiates a PDU session establishment process. Specifically, the terminal device carries the PDU session identifier, S-NSSAI and DNN and other parameters and sends it to the AMF. AMF selects SMF according to S-NSSAI and DNN, and sends the SMF network element's identity, the permanent identity of the terminal device, the location information of the terminal device, the PDU session identity, S-NSSAI and DNN to the SMF network element. Wherein, the location information of the terminal device includes the TAI of the terminal device.
  • the SMF obtains the correspondence between the deployment location of the application server, the domain name and the IP address of the application server through the PCF.
  • S803 The SMF determines the identity of the MEC platform currently accessible by the terminal device or the DNAI currently accessible by the terminal device according to the location information of the terminal device acquired in step S802.
  • the SMF sends the location of the terminal device determined in step S803 to UPF1, where the location of the terminal device can be the TAI of the terminal device, or the MEC platform identifier that the terminal device can currently access or the terminal device currently can Access to DNAI.
  • the location of the terminal device may also be the access network identifier of the current serving terminal device.
  • the access network identifier may be RAN ID or RAN IP address.
  • SMF sends instruction information to UPF1, which is used to instruct UPF1 to insert the location information of the terminal device into the DNS query request message after receiving the DNS query request from the UE.
  • the terminal device sends a DNS query request (query) to the core network UPF1 through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • the UPF1 After receiving the DNS query request, the UPF1 adds the location information of the terminal device received from the SMF in S8041 to the DNS request and sends it to the DNS server.
  • the location of the terminal device may include the TAI of the terminal device, or the identification of the MEC platform that the terminal device can currently access or the DNAI that the terminal device can currently access, and the location of the terminal device may include the access network currently serving the terminal device.
  • logo For example, the access network identifier may be RAN ID or RAN IP address.
  • UPF1 can also determine whether to send notification information to the SMF according to the domain name or destination address in the DNS query request message.
  • the notification information is used by the SMF to select the offload node (such as UL CL/BP) and the anchor UPF for the terminal device.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF in step S8041. When the domain name or destination address meets the first rule, UPF1 Send notification information to SMF.
  • UPF1 receives the identification information of the offload node and the anchor point UPF2 from the SMF.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • UPF1 determines to send notification information to SMF.
  • UPF1 determines that the destination address contained in the DNS query request satisfies the condition for sending the first notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the destination contained in the DNS query request
  • the address is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names includes one or more domain names.
  • UPF1 determines to send notification information to SMF. In other words, if UPF1 determines that the domain name contained in the DNS query request satisfies the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be that the domain name included in the DNS query request is the first Any domain name included in the rule.
  • UPF1 can send the DNS request to the DNS server in either of the following two ways.
  • UPF1 can add the identification information of UPF2 to the DNS request and send it to the DNS server.
  • UPF2 here can be understood as the anchor point UPF connected to the MEC platform closest to the current location of the terminal device.
  • the identification information of UPF2 may be UPF2ID or UPF2IP address.
  • the identification information of UPF2 is obtained by UPF1 from SMF.
  • UPF1 happens to be the anchor point UPF connected to the MEC platform closest to the current position of the terminal device, then after UPF1 receives the DNS query request, it adds UPF1's own identification information to the DNS request and Send to the DNS server.
  • UPF1 can send a notification message to the SMF network element, and the notification message contains the domain name requested by the terminal device.
  • SMF determines the management of the application server corresponding to the domain name requested by the terminal device based on the deployment location of the application server obtained in step S802, the correspondence between the domain name and the IP address of the application server, the domain name requested by the terminal device, and the TAI of the terminal device.
  • the location of the platform, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (ie, the location of the management platform) can be identified by DNAI.
  • the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the SMF sends the location information of the terminal device to UPF1, for UPF1 to insert the location information of the terminal device into the DNS request and send it to the DNS server.
  • the location information of the terminal device includes but is not limited to: the TAI of the terminal device, the DNAI used to identify the management platform, the identification information of the user plane function network element connected to the management platform, or the IP address pointing to the management platform .
  • the management platform is the management platform determined in the above description that deploys the application server corresponding to the domain name requested by the terminal device. For a specific description of the location information of the terminal device, reference may also be made to the description in step S231.
  • SMF determines the application corresponding to the domain name requested by the terminal device according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S802, the domain name requested by the terminal device, and the TAI of the terminal device
  • SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI), so as to implement local diversion of the application's business flow and reduce latency.
  • the DNS server determines the corresponding IP address according to the location information and domain name of the terminal device included in the DNS query request. Specifically, if the location information of the terminal device included in the DNS query request is the MEC platform identifier or DNAI, the DNS server determines the domain name to determine the corresponding IP address based on the first information stored in S801 and the MEC platform identifier or DNAI. If the location information of the terminal device contained in the DNS query request is the access network identification of the current service terminal device or UPF1 identification information, the DNS server first determines the MEC that the terminal device can currently access according to the access network identification or UPF1 identification information Platform ID or DNAI currently accessible by the terminal device. Further, the DNS server determines the domain name and the corresponding IP address according to the first information stored in S801 and the MEC platform ID or DNAI.
  • the DNS server returns the IP address to the UPF1 through a DNS response (response).
  • the UPF1 determines whether to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session management network element.
  • One notification information is used to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session management network
  • the first rule contains a list of IP addresses
  • the list of IP addresses contains one or more IP addresses, as long as the IP address of the application server in the DNS response (response) belongs to the list of IP addresses, then UPF1 will report to you according to the IP address SMF sends notification information.
  • UPF1 determines that the IP address in the DNS response message meets the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the application server in the DNS response (response)
  • the IP address is any IP address included in the first rule.
  • S8051 After the SMF selects UPF1, it sends a forwarding rule of the DNS query message to UPF1, which is used to instruct the UPF to forward the DNS query message to the SMF after receiving the DNS query message from the terminal device.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request may also include a destination address, and the destination address is the address of the DNS server.
  • the SMF determines the terminal device request according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S802, the domain name requested by the terminal device, and the TAI of the terminal device
  • the domain name corresponds to the location of the management platform where the application server is located.
  • the application server can serve the domain name requested by the terminal device.
  • the deployment location of the application server (the location of the management platform) can be identified by DNAI. Since the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the SMF adds the location information of the terminal device to the DNS request and sends it to the DNS server.
  • the location information of the terminal device includes but is not limited to: the TAI of the terminal device, the DNAI used to identify the management platform, the identification information of the user plane function network element connected to the management platform, or the IP address pointing to the management platform .
  • the management platform is the management platform determined in the above description that deploys the application server corresponding to the domain name requested by the terminal device. For a specific description of the location information of the terminal device, reference may also be made to the description in step S231.
  • the SMF may also determine whether to execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element is based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names, as long as the SMF network element receives If the domain name included in the DNS query request belongs to the domain name list, the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select the first offload node and the first PSA for the terminal device according to the destination address included in the DNS query request, where the destination address may be understood as the address of the DNS server.
  • SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location
  • SMF determines to select the first shunt node and the first PSA for the terminal device.
  • SMF chooses to insert BP
  • SMF also needs to allocate a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • the DNS server determines the corresponding IP address according to the location information and domain name of the terminal device included in the DNS query request. Specifically, if the location information of the terminal device included in the DNS query request is the MEC platform identifier or DNAI, the DNS server determines the domain name to determine the corresponding IP address based on the first information stored in S801 and the MEC platform identifier or DNAI. If the location information of the terminal device contained in the DNS query request is the currently serving UE's access network identification or UPF identification information, the DNS server first determines the MEC platform that the terminal device can currently access according to the access network identification or UPF identification information ID or the DNAI currently accessible by the terminal device.
  • the DNS server determines the domain name to determine the corresponding IP address according to the first information stored in S801 and the MEC platform ID or DNAI.
  • identification information of the UPF reference may be made to the description of the identification information of the UPF2 described in S8043 or S8044. For brevity, details are not repeated here.
  • the DNS server returns the IP address to the SMF through a DNS response message.
  • the SMF can execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains an IP address list, and the IP address list contains one or more IP addresses, as long as The IP address included in the DNS query response received by the SMF network element belongs to the IP address list, and the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (for example, IP-1 in Table 1) (for example, MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process. SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • IP-1 in Table 1 for example, MEC platform-2 in Table 1
  • SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • SMF/UPF determines the corresponding MEC platform based on the location information of the terminal device (for example, the IP address of the TAI or user plane function network element or the IP address of the wireless access network that the terminal accesses).
  • the ID or DNAI of the MEC platform, and the ID or DNAI of the MEC platform is added to the DNS query request.
  • the DNS server can also determine the MEC platform or DNAI according to the location of the terminal device (such as TAI). Therefore, after the SMF/UPF resolves the DNS message (DNS request), the location information of the terminal device ( For example, TAI) is added to the DNS request sent to the DNS server.
  • the DNS server determines the MEC platform identifier or DNAI according to the TAI, and further determines the application IP address according to the MEC platform identifier or DNAI and the domain name in the DNS request.
  • the DNS server is based on the information contained in the DNS query request.
  • the location information and domain name of the terminal device return the corresponding IP address.
  • the difference is that if the UPF actively adds the location information of the terminal device, once SMF detects that the terminal device moves, the location of the terminal device changes (for example, corresponding MEC platform ID or DNAI change), then SMF will send the location of the new terminal device (for example, the new MEC platform ID or DNAI) to UPF, so as to ensure that after UPF receives the DNS query request from the terminal device, it adds The latest location of the device corresponds to the latest MEC platform identifier or DNAI or the latest location information of the terminal device.
  • SMF If SMF actively adds the location of the terminal device, once SMF detects that the movement of the terminal device has caused the MEC platform ID or DNAI to change, then SMF will need a new MEC platform ID or DNA or the latest terminal device location The information is added to the DNS query request and sent to the DNS server.
  • the domain name query method enhances the DNS server so that the DNS server stores the deployment location of the application server (for example, the MEC platform identifier or DNAI), and the correspondence between the domain name and the IP address of the application server.
  • SMF/UPF resolves the DNS query request, it actively adds it to the DNS query request according to the location of the terminal device and sends it to the DNS server.
  • the DNS server returns the corresponding IP address according to the location and domain name of the terminal device contained in the DNS query request; further
  • SMF/UPF can also trigger SMF to insert ULCL/BP to optimize the path of local service access according to the DNS response message. It can ensure that the terminal device can obtain the IP address of the application nearby at the new location, and it can also dynamically insert ULCL/BP according to the service access to realize local offloading, optimize the service access path, and improve communication efficiency.
  • FIG. 15 is a schematic flowchart of a method 900 for querying a domain name system according to an embodiment of the present application.
  • the method 600 may be applied in the architecture shown in FIG. 1.
  • the process shown in Figure 15 mainly describes the ETSUN scenario where I-SMF/I-UPF actively adds the deployment location of the application server corresponding to its location according to the location of the terminal device (such as TAI) (it can be represented by the MEC platform identifier or DNAI) .
  • the method 900 includes:
  • the DNS server stores the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server (that is, the aforementioned first information).
  • the method for the DNS server to obtain the deployment location of the application server can be as follows: the AF determines the deployment location of the application server (for example, it can be represented by the MEC platform logo or DNAI), the correspondence between the domain name and the IP address of the application server (ie The above-mentioned first information) is stored in the DNS server. Further, the AF may also store the first information in the UDR through the NEF network element. For the specific description of this process, reference may be made to the description of S401 above. For brevity, details are not repeated here.
  • S902 The terminal device initiates a session establishment procedure at location-1 (for example, TAI-1).
  • location-1 for example, TAI-1
  • S903 The position of the terminal device has moved from position-1 (TAI-1) to position-2 (TAI-2).
  • TAI-1 position-1
  • TAI-2 position-2
  • the AMF executes the insertion of the I-SMF.
  • the I-SMF obtains the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server from the PCF through the SMF.
  • the I-SMF determines the identifier of the MEC platform currently accessible by the terminal device or the DNAI currently accessible by the terminal device according to the location information of the terminal device.
  • the location information of the terminal device is obtained by the I-SMF from the AMF, and the method of obtaining may be that after inserting the I-SMF, the I-SMF subscribes to the AMF for the location information of the terminal device. In this way, when the location of the terminal device moves, the AMF can provide the I-SMF with the latest location information where the terminal device is currently located.
  • I-SMF selects I-UPF, and sends the location of the terminal device determined in step S904 to I-UPF, where the location of the terminal device can be the TAI of the terminal device, or the MEC platform identifier corresponding to the TAI of the terminal device Or DNAI.
  • the location of the terminal device may also be the access network identifier of the current serving terminal device.
  • the access network identifier may be RAN ID or RAN IP address.
  • the I-SMF sends instruction information to the I-UPF, which is used to instruct the I-UPF to insert the location information of the terminal device into the DNS query message after receiving the DNS query message of the terminal device.
  • the I-SMF can directly send an N1SM message to the terminal device through the access network device.
  • the N1SM message contains the PCO.
  • the PCO contains the DNS cache update indication information to instruct the terminal device to initiate DNS. Cache update.
  • the I-SMF sends a user plane message to the terminal device through the I-UPF, and the message is used to instruct the terminal device to initiate DNS cache update.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of a certain application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the I-UPF After receiving the DNS query request, the I-UPF adds the location information of the terminal device received from the I-SMF in S9051 to the DNS request and sends it to the DNS server. Optionally, the I-UPF can also determine whether to send notification information to the I-SMF according to the domain name or destination address in the DNS query request message. The notification information is used by the I-SMF to select a shunt node for the terminal device (such as UL CL/ BP) and anchor UPF to optimize the path of business access.
  • a shunt node for the terminal device such as UL CL/ BP
  • the method for the I-UPF to determine to send notification information to the I-SMF may be: the first rule can be pre-configured on the I-UPF, or the I-UPF receives the first rule from the I-SMF, when the domain name or destination address meets In the first rule, I-UPF sends notification information to I-SMF.
  • the I-UPF receives the identification information of the offload node and the anchor point UPF2 from the I-SMF.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • the I-UPF will determine to -SMF sends notification information.
  • the I-UPF determines that the destination address contained in the DNS query request meets the condition for sending the first notification information to the I-SMF, then the I-UPF sends the notification information to the I-SMF, where the condition can be It is that the destination address included in the DNS query request is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names contains one or more domain names.
  • I-UPF determines to send a notification to I-SMF information.
  • I-UPF determines that the domain name contained in the DNS query request meets the conditions for sending notification information to I-SMF, then I-UPF sends notification information to I-SMF, where the condition can be a DNS query
  • the domain name included in the request is any domain name included in the first rule.
  • I-UPF does not receive the location information of the terminal device from I-SMF, then after I-UPF receives the DNS query request, I-UPF can send DNS to the DNS server in either of the following two ways request.
  • the I-UPF adds the identification information of UPF2 to the DNS request and sends it to the DNS server.
  • UPF2 here can be understood as the UPF connected to the MEC platform closest to the current location of the terminal device.
  • the identification information of UPF2 may be UPF2ID or UPF2IP address.
  • the second type: I-UPF can send a notification message to the I-SMF network element, and the notification message contains the domain name requested by the terminal device.
  • the I-SMF determines the location of the application server corresponding to the domain name requested by the terminal device according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S903, the domain name requested by the terminal device and the TAI of the terminal device.
  • the location of the management platform, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (the location of the management platform) can be identified by DNAI.
  • the location of the management platform Since the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the I-SMF sends the location information of the terminal device to the I-UPF for the I-UPF to insert the location information of the terminal device into the DNS query and send it to the DNS server.
  • the location information of the terminal device includes but is not limited to: the TAI of the terminal device, the DNAI used to identify the management platform, the identification information of the user plane function network element connected to the management platform, or the IP address pointing to the management platform .
  • the management platform is the management platform determined in the above description that deploys the application server corresponding to the domain name requested by the terminal device. For a specific description of the location information of the terminal device, reference may also be made to the description in step S231.
  • the I-SMF determines the correspondence of the domain name requested by the terminal device according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S903, the domain name requested by the terminal device, and the TAI of the terminal device
  • the I-SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI), so as to realize the local distribution of the application's business flow and reduce the delay.
  • the DNS server determines the corresponding IP address according to the location information and domain name of the terminal device included in the DNS query request. Specifically, if the location information of the terminal device included in the DNS query request is the MEC platform identifier or DNAI, the DNS server determines the domain name to determine the corresponding IP address according to the first information stored in S901 and the MEC platform identifier or DNAI. If the location information of the terminal device contained in the DNS query request is the access network identification of the current service terminal device or UPF identification information, the DNS server first determines the MEC that the terminal device can currently access according to the access network identification or UPF identification information The platform identifier or the DNAI currently accessible by the terminal device. Further, the DNS server determines the domain name to determine the corresponding IP address according to the first information stored in S901 and the MEC platform identifier or DNAI.
  • S9056 The DNS server returns the IP address to the I-UPF through DNS response.
  • the I-UPF determines whether to send notification information to the I-SMF according to the IP address contained in the DNS response message (for example, IP-1 in Table 1), and the notification information is used to notify the I-SMF to insert UL for the terminal device CL/BP, optimize the path of local business access.
  • the method for the I-UPF to determine to send notification information to the I-SMF may be: the I-UPF may pre-configure the first rule in advance, or the I-UPF may receive the first rule from the I-SMF, when the DNS response message contains When the IP address meets the first rule, I-UPF determines to send notification information to I-SMF.
  • the first rule includes an IP address list, and the IP address list includes one or more IP addresses.
  • the IP address in the DNS response message belongs to the IP address list (for example, IP-1 in Table 1), then I-UPF Based on the IP address, notification information is sent to the I-SMF.
  • the I-UPF determines that the IP address in the DNS response message meets the conditions for sending notification information to the I-SMF, then the I-UPF sends the notification information to the I-SMF, where the condition can be a DNS response
  • the IP address of the application server in (response) is any IP address included in the first rule.
  • the I-SMF selects the I-UPF, and sends a forwarding rule of the DNS query message to the I-UPF, which is used to instruct the I-UPF to forward the DNS query request to the I-SMF after receiving the DNS query request from the terminal device.
  • the I-SMF since the DNS resolution performed by the SMF before inserting the I-SMF, after inserting the I-SMF, the I-SMF does not know which application domain names the terminal device has queried before inserting, so the I-SMF needs to trigger the terminal device to update the DNS cache , So that the terminal device can obtain the IP address of the latest application server when it initiates a DNS query again at the current location (location-2).
  • the I-SMF can directly send an N1SM message to the terminal device through the access network device.
  • the N1SM message contains the PCO, and the PCO contains DNS cache update indication information for instructing the terminal device to initiate DNS Cache update.
  • the I-SMF sends a user plane message to the terminal device through the I-UPF, and the message is used to instruct the terminal device to initiate DNS cache update.
  • the terminal device sends a DNS query request (query) to the core network through the access network device to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the I-SMF determines the terminal according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S903, the domain name requested by the terminal device, and the TAI of the terminal device
  • the domain name requested by the device corresponds to the location of the management platform where the application server is located.
  • the application server can serve the domain name requested by the terminal device, and the deployment location of the application server can be identified by DNAI. Since the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the I-SMF adds the location information of the terminal device to the DNS request and sends it to the DNS server.
  • the location information of the terminal device includes but is not limited to: the TAI of the terminal device, the DNAI used to identify the management platform, the identification information of the user plane function network element connected to the management platform, or the IP address pointing to the management platform .
  • the management platform is the management platform determined in the above description that deploys the application server corresponding to the domain name requested by the terminal device. For a specific description of the location information of the terminal device, reference may also be made to the description in step S231.
  • the I-SMF may determine whether to perform the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the I-SMF network element in advance, or the I-SMF network element can pre-configure the domain name list according to the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names.
  • the domain name included in the DNS query request received by the I-SMF network element belongs to the domain name list, then the I-SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select UPF2 (PSA-2) and UL CL/BP for the terminal device according to the destination address included in the DNS query request, where the destination address can be understood as the address of the DNS server.
  • SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location, then SMF determines to select UPF2 (PSA-2) and UL CL/BP for the terminal device . If the I-SMF chooses to insert the BP through the above method, the I-SMF also needs to allocate a new IPv6 prefix to the terminal device and send it to the terminal device via PSA-1. Subsequent terminal devices can access the application server through PSA-2.
  • S9066 The DNS server determines the corresponding IP address according to the location and domain name of the terminal device included in the DNS query request.
  • the specific process is similar to S9055. For specific description, please refer to the above description of S9055. For brevity, details are not repeated here.
  • the DNS server returns the IP address to the I-SMF through a DNS response message.
  • the I-SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the I-SMF network element in advance, or the I-SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of IP addresses, and the IP address list contains one or more IP address, as long as the IP address contained in the DNS query response received by the I-SMF network element belongs to the IP address list, the I-SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes ULCL/BP insertion Process.
  • the I-SMF network element determines that the deployment location of the application server corresponding to the IP address (such as IP-1 in Table 1) (such as MEC platform-2 in Table 1) allows ULCL/BP insertion, then I-SMF Select UPF2 (PSA-2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • IP-1 in Table 1 such as MEC platform-2 in Table 1
  • PSA-2 I-SMF Select UPF2
  • the terminal device optimizes the path of local business access.
  • the above process is based on the I-SMF/I-UPF itself based on the location information of the terminal device (such as TAI or the IP address of the user plane function network element serving the terminal device or the wireless access network that the terminal accesses). IP address) to determine the corresponding MEC platform ID or DNAI, and add the MEC platform ID or DNAI to the DNS query request.
  • the DNS server itself determines the MEC platform or DNAI according to the location of the terminal device (such as TAI). Therefore, after the I-SMF/I-UPF resolves the DNS message (DNS request), it can also determine the location of the terminal device. Information (such as TAI) is added to the DNS request sent to the DNS server. After receiving the location information of the terminal device, the DNS server determines the MEC platform ID or DNAI according to TAI, and then further determines the application IP address according to the MEC platform ID or DNAI and the domain name in the DNS request
  • the DNS server is enhanced to enable the DNS server to store the deployment location of the application server and the correspondence between the domain name and the IP address of the application server.
  • the I-SMF/I-UPF resolves the DNS query request, it actively adds the location of the terminal device to the DNS query request and sends it to the DNS server.
  • the DNS server returns the corresponding IP address according to the location and domain name of the terminal device contained in the DNS query request.
  • the I-SMF/I-UPF triggers the I-SMF/insert ULCL/BP according to the DNS response message to optimize the local service access path. It can ensure that the terminal device can obtain the IP address of the application nearby at the new location, and it can also dynamically insert ULCL/BP according to the service access to realize local offloading, optimize the service access path, and improve communication efficiency.
  • FIG. 16 is a schematic flowchart of a method 600 for querying a domain name system according to an embodiment of the present application.
  • the method 600 may be applied in the architecture shown in FIG. 1.
  • the method shown in FIG. 16 is mainly that the location information of the UE can be obtained from the core network from the application function network element (for example, AF) through capability opening, and then the application function network element notifies the DNS server.
  • the DNS server determines the corresponding IP address according to the domain name included in the DNS query request and the above-mentioned location information of the terminal device and returns the IP address.
  • the method 1000 includes:
  • the DNS server stores the deployment location of the application server (for example, it can be represented by the MEC platform identifier or DNAI), the correspondence between the domain name and the IP address of the application server (that is, the aforementioned first information).
  • the method for the DNS server to obtain the deployment location of the application server can be as follows: the AF determines the deployment location of the application server (for example, it can be represented by the MEC platform logo or DNAI), the correspondence between the domain name and the IP address of the application server (ie The above-mentioned first information) is stored in the DNS server. Further, the AF may also store the first information in the UDR through the NEF network element. For the specific description of this process, reference may be made to the description of S401 above. For brevity, details are not repeated here.
  • S1002 The terminal device initiates a PDU session establishment process.
  • the AF requests the AMF or SMF to obtain the location information of the terminal device through the NEF, and the request message carries the identification of the terminal device.
  • the AMF or SMF sends the location information of the terminal device to the AF.
  • the location information of the terminal device can be the TAI of the terminal device, or the identification of the MEC platform that the terminal device can currently access or the DNAI that the terminal device can currently access, and the location of the terminal device can also be the access of the terminal device currently serving ⁇ logo.
  • the access network identifier may be RAN ID or RAN IP address.
  • the AF provides the location information of the terminal device to the DNS server.
  • the AF may also send the IP address and application identifier of the terminal device to the DNS server.
  • the DNS server stores this information.
  • the AF sends a subscription request to the DNS server, carrying the application identifier and the subscription event.
  • the subscription event may be: when the DNS server determines that the domain name of the application requested by the terminal device meets the conditions, the DNS server notifies the AF.
  • the domain name list can be pre-configured on the DNS server or the domain name list can be obtained by other methods.
  • the list contains one or more domain names.
  • the DNS server will notify the AF. In other words, as long as the domain name included in the DNS query request received by the DNS server network element meets the conditions for sending a subscription notification to the AF, the DNS server will send a subscription notification message to the AF.
  • the subscription event sent by the AF to the DNS server may also be: when the DNS server determines that the IP address of the application requested by the terminal device meets the condition, the DNS server notifies the AF.
  • the IP address list can be pre-configured on the DNS server or obtained by other methods.
  • the IP list contains one or more IP addresses, as long as the IP address contained in the DNS query request received by the DNS server network element is the IP address For any IP address in the address list, the DNS server will notify AF.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the UPF may also determine whether to send notification information to the SMF according to the domain name or destination address in the DNS query request message.
  • the notification information is used to notify the SMF to select the offload node and anchor point PSA-2 to optimize the service access path.
  • the method for UPF to determine to send notification information to SMF may be: the first rule can be pre-configured on UPF, or UPF receives the first rule from SMF, and when the domain name or destination address meets the first rule, UPF sends a notification to SMF information.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • the UPF determines to send notification information to the SMF.
  • UPF determines that the destination address contained in the DNS query request satisfies the condition for sending the first notification information to SMF, then UPF sends notification information to SMF, where the condition can be the destination contained in the DNS query request
  • the address is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names includes one or more domain names.
  • UPF determines to send notification information to SMF.
  • the condition can be that the domain name contained in the DNS query request is the first Any domain name included in the rule.
  • the SMF may obtain the DNS query request, and determine whether to perform the ULCL/BP insertion process according to the domain name or the destination address included in the DNS query request.
  • the specific process refer to the description of S612. For brevity, details are not repeated here.
  • the DNS server determines the corresponding IP address according to the location information of the terminal device and the domain name. Specifically, if the location information of the terminal device included in the DNS query request is the MEC platform identifier or DNAI, the DNS server determines the domain name to determine the corresponding IP address based on the first information stored in S1001 and the MEC platform identifier or DNAI. If the location information of the terminal device included in the DNS query request is the access network identification information of the current service terminal device, then the DNS server first determines the MEC platform identification that the terminal device can currently access or the terminal device currently can access according to the access network identification information. The accessed DNAI, further, the DNS server determines the domain name to determine the corresponding IP address according to the first information stored in S801 and the MEC platform identifier or DNAI.
  • the DNS server according to the subscription request in step S1006, if the DNS server determines that the domain name or IP address of the application requested by the terminal device meets the conditions for sending a subscription notification to the AF, then the DNS server sends subscription notification information to the AF,
  • the subscription notification information carries indication information.
  • the indication information is used to indicate AF: The domain name or IP address that meets the conditions is obtained in this DNS query.
  • the DNS temporarily does not send a DNS response message to the terminal device, and has been waiting for a reply from the AF.
  • the AF sends indication information to the SMF through the NEF, which is used to instruct the SMF to perform offloading for the PDU session of the terminal device.
  • S1012 SMF selects PSA and UL CL/BP, and executes the ULCL/BP insertion process to optimize the path of business access.
  • the SMF sends notification information to the AF, which is used to notify the AF that the PDU session offload of the terminal device is successful.
  • S1014 The AF sends a notification message to the DNS server to notify the DNS to return the IP address of the application to the terminal device.
  • S1015 The DNS server returns the IP address of the application to the terminal device in the DNS response message.
  • the DNS server can obtain the location information of the terminal device by itself, and determine the IP address of the application server corresponding to the position and domain name of the terminal device in conjunction with the domain name information contained in the DNS query request of the terminal device. And feedback the IP address of the application server to the terminal device. Improve the efficiency of the DNS server to determine the IP address of the application server.
  • FIG. 17 is a schematic flowchart of a method 1100 for querying a domain name system according to an embodiment of the present application.
  • the method 1100 may be applied in the architecture shown in FIG. 1.
  • the process shown in Figure 17 mainly describes the enhancement of the DNS server in the scenario where the N6 interface connected to the MEC platform adopts NAT translation, so that the DNS server stores the above-mentioned deployment location of the application server, the domain name and the IP address of the application server.
  • the DNS server also stores the correspondence between the public network IP address space (public network IP address range) at the entrance of the MEC platform and the deployment location of the application server (indicated by DNAI).
  • the public IP address space includes multiple public IPs.
  • SMF determines the MEC platform (indicated by DNAI) of the application server corresponding to the domain name requested by the terminal device based on the current TAI information of the terminal device, and then determines the corresponding public network IP address space based on the DNAI.
  • the public network IP address space includes at least one IP address, and any public network IP address included in the public network IP address space can point to the MEC platform.
  • the management platform is the management platform where the application server corresponding to the domain name queried by the terminal device is located.
  • the DNS server determines the location of the MEC platform according to the public IP address contained in the DNS query request, and further determines the IP address of the application server corresponding to the domain name queried by the terminal device on the MEC platform.
  • the DNS server returns the address corresponding to the domain name and public IP address. Indicates the IP address of the application server corresponding to the location of the terminal device.
  • the SMF can also insert ULCL/BP for the terminal device according to the IP address in the DNS response message to optimize the local service access path.
  • the session management network element takes SMF as an example
  • the policy control function network element takes PCF as an example
  • the user plane function network element takes UPF as an example
  • the application function network element takes AF as an example.
  • the method 1100 includes:
  • SMF obtains the public network IP address space at the entrance of the MEC platform.
  • the public network IP address space includes at least one IP address, and any public network IP address included in the public network IP address space can be connected to the MEC platform.
  • the DNS server stores the deployment location of the application (for example, it can be represented by the MEC platform logo or DNAI), the correspondence between the domain name and the IP address.
  • the DNS server also stores the correspondence between the public IP address at the entrance of the MEC platform and the deployment location of the application server (indicated by DNAI).
  • Method 1 Configure the public IP address space connected to the entrance of each MEC platform on the SMF, and the location of the MEC platform can be identified by DNAI. That is, SMF stores the correspondence between DNAI and the public network IP address space.
  • the public network IP address space can be represented by 128.128.0.0 to 128.128.255.255.
  • Method 2 AF sends the deployment location corresponding to the application (the deployment location corresponding to the application is represented by DNAI), and the public network IP address space (public network IP address range) at the entrance of the MEC platform corresponding to the DNAI is sent to the UDR network element through NEF. That is, UDR stores the correspondence between DNAI and the public network IP address space.
  • the public network IP address space can be represented by 128.128.0.0 to 128.128.255.255.
  • SMF can obtain the public network IP address space at the entrance of the MEC platform from the UDR through the PCF during the session establishment process.
  • the terminal device initiates a PDU session establishment process. Specifically, the terminal device carries the PDU session identifier, S-NSSAI and DNN and other parameters and sends it to the AMF. AMF selects SMF according to S-NSSAI and DNN, and sends the SMF network element's identity, the permanent identity of the terminal device, the location information of the terminal device, the PDU session identity, S-NSSAI and DNN to the SMF network element. Wherein, the location information of the terminal device includes the TAI of the terminal device.
  • the SMF determines the identity of the MEC platform currently accessible by the terminal device or the DNAI currently accessible by the terminal device according to the location information (ie TAI) of the terminal device acquired in step S1102. at the same time.
  • the SMF determines the location DNAI of the MEC platform according to the current location of the terminal device, and further determines the public network IP address space at the entrance of the MEC platform corresponding to the DNAI.
  • SMF selects UPF1 for the PDU session, and sends indication information and public IP address to UPF1.
  • the indication information is used to indicate UPF1: After receiving the DNS query request from the terminal device, add the public IP address to the DNS query request , The public IP address points to
  • UPF1 is the UPF connected to the DNS server, that is, UPF1 can access the DNS server.
  • S1105 The SMF sends a session acceptance message to the terminal device, carrying DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network UPF1 through the access network device to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • UPF1 After receiving the DNS query request, UPF1 adds the public IP address received from SMF in S1104 to the DNS request and sends it to the DNS server.
  • UPF1 can also determine whether to send notification information to the SMF according to the domain name or destination address in the DNS query request message.
  • the notification information is used by the SMF to select the offload node (such as UL CL/BP) and the anchor UPF for the terminal device.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF in step S8041. When the domain name or destination address meets the first rule, UPF1 Send notification information to SMF.
  • UPF1 receives the identification information of the offload node and the anchor point UPF2 from the SMF.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • UPF1 determines to send notification information to SMF.
  • UPF1 determines that the destination address contained in the DNS query request satisfies the condition for sending the first notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the destination contained in the DNS query request
  • the address is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names includes one or more domain names.
  • UPF1 determines to send notification information to SMF. In other words, if UPF1 determines that the domain name contained in the DNS query request satisfies the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be that the domain name included in the DNS query request is the first Any domain name included in the rule.
  • UPF1 does not receive an IP address from SMF, after UPF1 receives the DNS query request, UPF1 can send a DNS request to the DNS server in the following manner.
  • the method is: UPF1 can send a notification message to the SMF network element, and the notification message contains the domain name requested by the terminal device.
  • SMF determines the management of the application server corresponding to the domain name requested by the terminal device based on the deployment location of the application server obtained in step S1101, the correspondence between the domain name and the IP address of the application server, the domain name requested by the terminal device, and the TAI of the terminal device.
  • the location of the platform, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (ie, the location of the management platform) can be identified by DNAI.
  • the location of the management platform corresponds to the location of the terminal device.
  • the SMF sends the IP address pointing to the management platform to UPF1 for UPF1 to insert the IP address into the DNS query and send it to the DNS server.
  • the IP address points to the MEC platform where the application server corresponding to the domain name requested by the terminal device is located.
  • the IP address may be a public IP address, and the public IP address is any public IP address in the public IP address space at the entrance of the MEC platform where the application server corresponding to the domain name requested by the terminal device is located.
  • SMF determines the application corresponding to the domain name requested by the terminal device according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S802, the domain name requested by the terminal device, and the TAI of the terminal device
  • SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI), so as to implement local diversion of the application's business flow and reduce latency.
  • the DNS server determines the corresponding IP address according to the public IP address and domain name included in the DNS query request. Specifically, the DNS query request includes the public network IP address, and the DNS server determines the MEC platform identifier currently accessible by the terminal device or the terminal device currently accessible according to the MEC platform identifier stored in S1101 or the correspondence between the DNAI and the public network IP address Further, the DNS server determines the domain name to determine the corresponding IP address according to the stored first information and the MEC platform identifier or DNAI.
  • S1109 The DNS server returns the IP address to UPF1 through a DNS response (response).
  • the UPF1 determines whether to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert the UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session management network element.
  • One notification information is used to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert the UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session
  • the first rule contains a list of IP addresses
  • the list of IP addresses contains one or more IP addresses, as long as the IP address of the application server in the DNS response (response) belongs to the list of IP addresses, then UPF1 will report to you according to the IP address SMF sends notification information.
  • UPF1 determines that the IP address in the DNS response message meets the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the application server in the DNS response (response)
  • the IP address is any IP address included in the first rule.
  • S1111 The SMF selects UPF1 for the PDU session, and sends a forwarding rule of the DNS query message to UPF1 to instruct the UPF to forward the DNS query message to the SMF after receiving the DNS query message from the terminal device.
  • the SMF sends a session acceptance message to the terminal device, which carries DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request may also include a destination address, and the destination address is the address of the DNS server.
  • S1114 After receiving the DNS query request, UPF1 forwards the DNS query request to the SMF.
  • S1115 After receiving the DNS query request, the SMF determines the application corresponding to the domain name requested by the terminal device according to the deployment location of the application server, the correspondence between the domain name and the IP address of the application server, the domain name requested by the terminal device, and the TAI of the terminal device.
  • the location of the management platform where the server is located, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (that is, the location of the management platform) can be identified by DNAI.
  • the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the SMF adds the public IP address pointing to the management platform to the DNS request and sends it to the DNS server.
  • the public IP address is any public IP address in the public IP address space at the entrance of the MEC platform where the application server corresponding to the domain name requested by the terminal device is located.
  • the public IP address space is 128.128.0.0 to 128.128.255.255, then SMF can use 128.128.1.1 belonging to the public IP address space as the public IP address at the entrance of the MEC platform.
  • the SMF may also determine whether to execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element is based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names, as long as the SMF network element receives If the domain name included in the DNS query request belongs to the domain name list, the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select the first offload node and the first PSA for the terminal device according to the destination address included in the DNS query request, where the destination address may be understood as the address of the DNS server.
  • the SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location, the SMF determines to select the first shunt node and the first PSA for the terminal device.
  • a third party such as Tencent, Ali
  • S1116 The NS server determines the corresponding IP address according to the public IP address and domain name contained in the DNS query request. For this step, refer to the description in S1108. For brevity, it will not be repeated here.
  • the DNS server returns the IP address to the SMF through a DNS response message.
  • the SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains an IP address list, and the IP address list contains one or more IP addresses, as long as The IP address included in the DNS query response received by the SMF network element belongs to the IP address list, and the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (for example, IP-1 in Table 1) (for example, MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process. SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • IP-1 in Table 1 for example, MEC platform-2 in Table 1
  • SMF selects UPF2 (PSA -2) and UL CL/BP, and execute the ULCL/BP insertion process.
  • SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • the DNS server determines the MEC platform corresponding to the current location of the terminal device according to the public network IP address contained in the DNS query request, and determines the IP address corresponding to the application server on the MEC platform according to the domain name requested by the terminal device.
  • the process of DNS query of the terminal device in the mobile scenario is similar to that of Figure 17 above.
  • the difference is that if UPF actively adds the location information of the terminal device, then once SMF detects that the terminal device moves, the location of the terminal device changes (for example, corresponding MEC platform ID or DNAI change), then SMF should send the public network IP address of the MEC platform corresponding to the location of the new terminal device (for example, the new MEC platform ID or DNAI) to UPF, so as to ensure that UPF receives the terminal After the device's DNS query request, the public IP address corresponding to the latest location of the terminal device is added.
  • the location of the terminal device changes (for example, corresponding MEC platform ID or DNAI change)
  • SMF should send the public network IP address of the MEC platform corresponding to the location of the new terminal device (for example, the new MEC platform ID or DNAI) to UPF, so as to ensure that UPF receives the terminal After the device's DNS query request, the public IP address corresponding to the latest location of the terminal device is added.
  • SMF If SMF actively adds the location of the terminal device, once SMF detects that the movement of the terminal device causes a change in the MEC platform identity or DNAI, and further causes a change in the public network IP address, then SMF will create a new public network The IP address is added to the DNS query request sent to the DNS server.
  • the DNS server is enhanced so that the DNS server stores the deployment location of the application server (such as the MEC platform identifier or DNAI), domain name, and application server The corresponding relationship between the IP addresses of the terminal device, and the corresponding relationship between the public network IP address at the entrance of the MEC platform of the terminal device and the deployment location of the application server.
  • SMF/UPF resolves the DNS query request, it actively adds the public IP address pointing to the management platform to the DNS query request and sends it to the DNS server.
  • the management platform is the management where the application server corresponding to the domain name requested by the terminal device is located. platform.
  • the DNS server returns the IP address of the corresponding application server according to the public IP address and domain name contained in the DNS query request; further, the SMF/UPF can also trigger the SMF to insert ULCL/BP to optimize the path of local business access according to the DNS response message. It can ensure that the terminal device can obtain the IP address of the application nearby at the new location, and it can also dynamically insert ULCL/BP according to the service access to realize local offloading, optimize the service access path, and improve communication efficiency.
  • FIG. 18 is a schematic flowchart of a method 1200 for querying a domain name system according to an embodiment of the present application.
  • the method 1200 may be applied in the architecture shown in FIG. 1.
  • STUN simple traversal utilities for NAT
  • the SMF can send a request message to the UPF connected to the MEC platform to request the UPF to use the STUN protocol to obtain the public network IP address and port number after the NAT.
  • the process shown in Figure 18 is that after UPF uses the STUN protocol to obtain the public network IP address after NAT and the port number corresponding to the public network IP address, it sends the public network IP address, or the public network IP address and the port number.
  • the DNS server also stores the correspondence between the public IP address at the entrance of the MEC platform and the deployment location of the application server (indicated by DNAI).
  • SMF/UPF resolves the DNS message (DNS query request)
  • the management platform is the management where the application server corresponding to the domain name requested by the terminal device is located. platform.
  • the SMF/UPF sends the DNS query request including the domain name queried by the terminal device and the public IP address to the DNS server.
  • the DNS server returns the IP address of the application server corresponding to the location of the domain name and public IP address according to the DNS query request.
  • the method 1200 includes:
  • the AF stores the deployment location of the application server (for example, it can be represented by the MEC platform identifier or DNAI) and the domain name supported by the application server in the UDR through the NEF network element.
  • the terminal device initiates the PDU session establishment process. Specifically, the terminal device carries the PDU session identifier, S-NSSAI and DNN and other parameters and sends it to the AMF. AMF selects SMF according to S-NSSAI and DNN, and sends the SMF network element's identity, the permanent identity of the terminal device, the location information of the terminal device, the PDU session identity, S-NSSAI and DNN to the SMF network element. Wherein, the location information of the terminal device includes the TAI of the terminal device.
  • the SMF selects UPF1 for the PDU session, and the UPF1 can be connected to the DNS server, that is, the UPF1 can access the DNS server.
  • the SMF determines that the current location corresponds to an MEC platform according to the current location of the terminal device, and further determines the UPF2 to which the MEC platform is connected. Optionally, if there are multiple UPFs connected to the MEC platform, here, the SMF can select one of the multiple UPFs as UPF2.
  • the SMF sends a request message to the UPF2 connected to the MEC platform.
  • the request message contains indication information, which is used to request the UPF2 to obtain the public network IP address and port number after the NAT.
  • UPF2 After receiving the instruction information, UPF2 uses the STUN protocol to detect the public network IP address and port number after the NAT.
  • UPF2 sends the public network IP address to the SMF network element.
  • this public IP address can also be called the public IP address at the entrance of the MEC platform.
  • UPF2 also sends the port number corresponding to the public IP address to the SMF.
  • S1207 The SMF sends instruction information to UPF1, the instruction information includes the public network IP address, and the instruction information is used to indicate UPF1:
  • the DNS query request message After receiving the DNS query request message from the terminal device, add the public network IP address to the DNS query request.
  • the IP address is the public IP address at the entrance of the MEC platform obtained by SMF in S1206.
  • SMF can also send the port number corresponding to the public IP address to UPF1 for UPF1 to also send the port number corresponding to the public IP address. Added to the DNS query request message.
  • the SMF sends a session acceptance message to the terminal device, which carries DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network UPF1 through the access network device according to its own business requirements to initiate a DNS query of a certain application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • UPF1 After receiving the DNS query request, UPF1 adds the public IP address received from SMF in S1207 to the DNS request and sends it to the DNS server. Optionally, if UPF1 receives the port number corresponding to the public IP address in S1207, UPF1 can also add the port number to the DNS query request.
  • UPF1 can also determine whether to send notification information to the SMF according to the domain name or destination address in the DNS query request message.
  • the notification information is used by the SMF to select the offload node (such as UL CL/BP) and the anchor UPF for the terminal device.
  • the method for UPF1 to determine to send notification information to SMF can be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the domain name or destination address meets the first rule, UPF1 sends a notification to SMF information.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • UPF1 determines to send notification information to SMF.
  • UPF1 determines that the destination address contained in the DNS query request satisfies the condition for sending the first notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the destination contained in the DNS query request
  • the address is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names includes one or more domain names.
  • UPF1 determines to send notification information to SMF. In other words, if UPF1 determines that the domain name contained in the DNS query request satisfies the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be that the domain name included in the DNS query request is the first Any domain name included in the rule.
  • UPF1 If in S1207, UPF1 does not receive an IP address from SMF, after UPF1 receives the DNS query request, UPF1 can send a DNS request to the DNS server in the following manner.
  • the method is: UPF1 can send a notification message to the SMF network element, and the notification message contains the domain name requested by the terminal device.
  • SMF determines the management of the application server corresponding to the domain name requested by the terminal device according to the deployment location of the application server obtained in step S1204, the correspondence between the domain name and the IP address of the application server, the domain name requested by the terminal device, and the TAI of the terminal device.
  • the location of the platform, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (ie, the location of the management platform) can be identified by DNAI.
  • the location of the management platform corresponds to the location of the terminal device.
  • the SMF sends the IP address pointing to the management platform to UPF1 for UPF1 to insert the IP address into the DNS query and send it to the DNS server.
  • the IP address points to the MEC platform where the application server corresponding to the domain name requested by the terminal device is located.
  • the IP address may be a public IP address, and the public IP address is any public IP address in the public IP address space at the entrance of the MEC platform where the application server corresponding to the domain name requested by the terminal device is located.
  • SMF determines the application corresponding to the domain name requested by the terminal device according to the corresponding relationship between the deployment location of the application server, the domain name and the IP address of the application server obtained in step S802, the domain name requested by the terminal device, and the TAI of the terminal device
  • SMF can also select UL CL/BP according to the deployment location of the application server (identified by DNAI), so as to implement local diversion of the application's business flow and reduce latency.
  • the DNS server determines the corresponding IP address according to the public network IP address and domain name included in the DNS query request. Specifically, the DNS query request includes the public network IP address, and the DNS server determines the MEC platform identifier currently accessible by the terminal device or the terminal device currently accessible according to the stored MEC platform identifier or the correspondence between the DNAI and the public network IP address DNAI, further, the DNS server determines the domain name to determine the corresponding IP address according to the stored first information and the MEC platform identifier or DNAI.
  • S1212 The DNS server returns the IP address to the UPF1 through a DNS response (response).
  • UPF1 determines whether to send notification information to the SMF according to the IP address in the DNS response message, where the notification information is used to notify the SMF to insert UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session management network element.
  • One notification information is used to notify the SMF to insert UL CL/BP for the terminal device to optimize the service access path.
  • the first rule contains a list of IP addresses
  • the list of IP addresses contains one or more IP addresses, as long as the IP address of the application server in the DNS response (response) belongs to the list of IP addresses, then UPF1 will report to you according to the IP address SMF sends notification information.
  • UPF1 determines that the IP address in the DNS response message meets the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the application server in the DNS response (response)
  • the IP address is any IP address included in the first rule.
  • S1214 The SMF selects UPF1 for the PDU session, and sends a forwarding rule of the DNS query message to UPF1, which is used to instruct the UPF to forward the DNS query message to the SMF after receiving the DNS query message from the terminal device.
  • the SMF sends a session acceptance message to the terminal device, which carries DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request may also include a destination address, and the destination address is the address of the DNS server.
  • the SMF determines the application corresponding to the domain name requested by the terminal device according to the deployment location of the application server, the correspondence between the domain name and the IP address of the application server, the domain name requested by the terminal device, and the TAI of the terminal device.
  • the location of the management platform where the server is located, the application server can serve the domain name requested by the terminal device, and the deployment location of the application server (that is, the location of the management platform) can be identified by DNAI. Since the location of the management platform is determined according to the TAI of the terminal device and the domain name requested by the terminal device, the location of the management platform corresponds to the location of the terminal device, and the management platform deploys an application server corresponding to the domain name requested by the terminal device.
  • the SMF adds the public IP address pointing to the management platform to the DNS request and sends it to the DNS server.
  • the public IP address is obtained in S1206, and the public IP address is any public IP address in the public IP address space at the entrance of the MEC platform corresponding to the current location of the terminal device.
  • SMF can also add the port number corresponding to the public IP address in the DNS query request.
  • the SMF may also determine whether to execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element is based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names, as long as the SMF network element receives If the domain name included in the DNS query request belongs to the domain name list, the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select the first offload node and the first PSA for the terminal device according to the destination address included in the DNS query request, where the destination address may be understood as the address of the DNS server.
  • the SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed at the current location, the SMF determines to select the first shunt node and the first PSA for the terminal device.
  • a third party such as Tencent, Ali
  • S1219 The DNS server determines the corresponding IP address according to the public IP address and domain name included in the DNS query request. For this step, refer to the description in S1108. For brevity, it will not be repeated here.
  • the DNS server returns the IP address to the SMF through a DNS response message.
  • the SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains an IP address list, and the IP address list contains one or more IP addresses, as long as The IP address included in the DNS query response received by the SMF network element belongs to the IP address list, then the SMF network element selects UPF (PSA) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (such as IP-1 in Table 1) (such as MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF and UL CL/BP, and execute the ULCL/BP insertion process. SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • IP-1 in Table 1 such as MEC platform-2 in Table 1
  • the DNS server is enhanced so that the DNS server stores the deployment location of the application server (such as the MEC platform identifier or DNAI) and the domain name Correspondence with the IP address of the application server, and store the correspondence between the public network IP address at the entrance of the MEC platform of the terminal device and the deployment location of the application server.
  • the SMF/UPF resolves the DNS query request, it obtains the public IP address pointing to the management platform, which is the management platform where the application server corresponding to the domain name requested by the terminal device is located.
  • SMF/UPF actively adds the public IP address to the DNS query request and sends it to the DNS server.
  • the DNS server returns the IP address of the corresponding application server according to the public IP address and domain name contained in the DNS query request; further, SMF/ UPF can also trigger SMF to insert ULCL/BP to optimize the path of local business access according to the DNS response message. It can ensure that the terminal device can obtain the IP address of the application nearby at the new location, and it can also dynamically insert ULCL/BP according to the service access to realize local offloading, optimize the service access path, and improve communication efficiency.
  • FIG. 19 is a schematic flowchart of a method 1300 for querying a domain name system according to an embodiment of the present application.
  • the method 1300 may be applied to the architecture shown in FIG. 1.
  • STUN allows clients on the internal network to discover the address translator in the network, and then find the external network IP and port configured by NAT. Therefore, SMF can also directly request the STUN server to obtain the public network IP address and port number after NAT.
  • the DNS server also stores the correspondence between the public IP address at the entrance of the MEC platform and the deployment location of the application server (indicated by DNAI).
  • SMF/UPF resolves the DNS message (DNS query request), it actively adds the public IP address pointing to the management platform to the DNS query request.
  • the management platform is the management where the application server corresponding to the domain name requested by the terminal device is located. platform.
  • the SMF/UPF sends the DNS query request including the domain name queried by the terminal device and the public IP address to the DNS server.
  • the public IP address may be any public IP address included in the public IP address space at the entrance of the management platform where the application server corresponding to the domain name requested by the terminal device is located.
  • the DNS server returns the IP address of the application server corresponding to the location of the domain name and public IP address according to the DNS query request.
  • the method 1300 includes:
  • the terminal device initiates a PDU session establishment process. Specifically, the terminal device carries the PDU session identifier, S-NSSAI and DNN and other parameters and sends it to the AMF. AMF selects SMF according to S-NSSAI and DNN, and sends the SMF network element's identity, the permanent identity of the terminal device, the location information of the terminal device, the PDU session identity, S-NSSAI and DNN to the SMF network element. Wherein, the location information of the terminal device includes the TAI of the terminal device.
  • the SMF selects UPF1 for the PDU session.
  • the UPF1 can be connected to the DNS server, that is, the UPF1 can access the DNS server.
  • the SMF determines that the current location corresponds to an MEC platform according to the current location of the terminal device, and further determines the UPF2 to which the MEC platform is connected. Optionally, if there are multiple UPFs connected to the MEC platform, here, the SMF can select one of the multiple UPFs as UPF2.
  • the SMF sends a request message to the STUN server, carrying the IP address of UPF2 connected to the MEC platform, where the IP address of the UPF2 is the private network IP address in the 3GPP internal network, and the STUN server determines the post-NAT based on the IP address of the UPF2 IP address of the public network.
  • the specific process can be that the STUN server can configure a one-to-one relationship between the private IP address of the 3GPP internal network and the public IP address. Among them, this public IP address can also be called the public IP address at the entrance of the MEC platform.
  • the STUN server also sends the port number corresponding to the public IP address to the SMF.
  • the STUN server sends the public IP address to the SMF.
  • the port number corresponding to the public IP address can also be sent to the SMF.
  • the SMF sends instruction information and the public IP address to UPF1.
  • the instruction information includes the public IP address.
  • the instruction information is used to indicate UPF1:
  • SMF can also send the port number corresponding to the public IP address to UPF1 for UPF1 to also send the port number corresponding to the public IP address. Added to the DNS query request message.
  • the SMF sends a session acceptance message to the terminal device, which carries DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network UPF1 through the access network device to initiate a DNS query of an application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request includes a destination address, and the destination address is the address of the DNS server.
  • the domain name corresponding to the application carried in the DNS query request may be an FQDN or another form of domain name, which is not limited in this application.
  • UPF1 After receiving the DNS query request, UPF1 adds the public IP address received from SMF in S1306 to the DNS request and sends it to the DNS server. Optionally, if UPF1 receives the port number corresponding to the public IP address in S1306, UPF1 can also add the port number to the DNS query request.
  • UPF1 can also determine whether to send notification information to the SMF according to the domain name or destination address in the DNS query request message.
  • the notification information is used by the SMF to select the offload node (such as UL CL/BP) and the anchor UPF for the terminal device.
  • the method for UPF1 to determine to send notification information to SMF can be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the domain name or destination address meets the first rule, UPF1 sends a notification to SMF information.
  • the first rule includes a destination address list.
  • the destination address list contains one or more destination addresses.
  • UPF1 determines to send notification information to SMF.
  • UPF1 determines that the destination address contained in the DNS query request satisfies the condition for sending the first notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the destination contained in the DNS query request
  • the address is any destination address included in the first rule.
  • the first rule includes a list of domain names.
  • the list of domain names contains one or more domain names.
  • UPF1 determines to send notification information to SMF.
  • UPF1 determines that the domain name contained in the DNS query request satisfies the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be that the domain name included in the DNS query request is the first Any domain name included in the rule.
  • the DNS server determines the corresponding IP address according to the public network IP address and domain name included in the DNS query request.
  • the DNS query request includes the public network IP address
  • the DNS server determines the MEC platform identifier currently accessible by the terminal device or the terminal device currently accessible according to the stored MEC platform identifier or the correspondence between the DNAI and the public network IP address DNAI
  • the DNS server determines the domain name to determine the corresponding IP address according to the stored first information and the MEC platform identifier or DNAI.
  • the DNS server returns the IP address to the UPF1 through a DNS response (response).
  • the UPF1 determines whether to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert the UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session management network element.
  • One notification information is used to send notification information to the SMF according to the IP address in the DNS response message.
  • the notification information is used to notify the SMF to insert the UL CL/BP for the terminal device to optimize the service access path.
  • the method for UPF1 to determine to send notification information to SMF may be: UPF1 can pre-configure the first rule in advance, or UPF1 receives the first rule from SMF, and when the IP address meets the first rule, UPF1 sends the first rule to the session
  • the first rule contains a list of IP addresses
  • the list of IP addresses contains one or more IP addresses, as long as the IP address of the application server in the DNS response (response) belongs to the list of IP addresses, then UPF1 will report to you according to the IP address SMF sends notification information.
  • UPF1 determines that the IP address in the DNS response message meets the conditions for sending notification information to SMF, then UPF1 sends notification information to SMF, where the condition can be the application server in the DNS response (response)
  • the IP address is any IP address included in the first rule.
  • S1313 After the SMF selects UPF1, it sends a forwarding rule of the DNS query message to UPF1, which is used to instruct the UPF to forward the DNS query message to the SMF after receiving the DNS query message from the terminal device.
  • S1314 The SMF sends a session acceptance message to the terminal device, which carries DNS server address information.
  • the terminal device sends a DNS query request (query) to the core network through the access network device according to its own business requirements to initiate a DNS query of a certain application, and the DNS query carries the domain name corresponding to the application.
  • the DNS query request may also include a destination address, and the destination address is the address of the DNS server.
  • S1317 After receiving the DNS query request, the SMF adds the public IP address to the DNS request and sends it to the DNS server.
  • the public IP address is obtained in S1305, and the public IP address is any public IP address in the public IP address space at the entrance of the MEC platform corresponding to the current location of the terminal device.
  • SMF can also add the port number corresponding to the public IP address in the DNS query request.
  • the SMF may also determine whether to execute the ULCL/BP insertion process according to the domain name included in the DNS query request.
  • the domain name list can be pre-configured on the SMF network element in advance, or the SMF network element is based on the PCC rule received from the PCF network element.
  • the PCC rule contains a list of domain names, and the domain name list contains one or more domain names, as long as the SMF network element receives If the domain name included in the DNS query request belongs to the domain name list, the SMF network element selects UPF2 (PSA-2) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF may also determine whether to select the first offload node and the first PSA for the terminal device according to the destination address included in the DNS query request, where the destination address may be understood as the address of the DNS server.
  • the SMF determines that the address of the DNS server points to a third party (such as Tencent, Ali), and the third-party application server is deployed in the current location, the SMF determines to select the first shunt node and the first PSA for the terminal device.
  • a third party such as Tencent, Ali
  • S1318 The DNS server determines the corresponding IP address according to the public network IP address and domain name included in the DNS query request. For this step, refer to the description in S1108. For brevity, it will not be repeated here.
  • the DNS server returns the IP address to the SMF through a DNS response message.
  • the SMF may execute the ULCL/BP insertion process according to the DNS query response.
  • the IP address list can be pre-configured on the SMF network element in advance, or the SMF network element can be based on the PCC rule received from the PCF network element.
  • the PCC rule contains an IP address list, and the IP address list contains one or more IP addresses, as long as The IP address included in the DNS query response received by the SMF network element belongs to the IP address list, then the SMF network element selects UPF (PSA) and UL CL/BP, and executes the ULCL/BP insertion process.
  • the SMF network element determines that the deployment location of the application server corresponding to the IP address (such as IP-1 in Table 1) (such as MEC platform-2 in Table 1) allows ULCL/BP insertion, then SMF selects UPF and UL CL/BP, and execute the ULCL/BP insertion process. SMF inserts UL CL/BP for the terminal device to optimize the path of business access.
  • IP-1 in Table 1 such as MEC platform-2 in Table 1
  • the DNS server is enhanced so that the DNS server stores the deployment location of the application server (such as the MEC platform identifier or DNAI) and the domain name Correspondence with the IP address of the application server, and store the correspondence between the public network IP address at the entrance of the MEC platform of the terminal device and the deployment location of the application server.
  • SMF/UPF resolves the DNS query request, it obtains the public IP address corresponding to the location of the terminal device, and actively adds the public IP address corresponding to the location of the terminal device to the DNS query request and sends it to the DNS server.
  • the DNS server The public IP address and domain name contained in the query request return the corresponding IP address; further, SMF/UPF can also trigger SMF to insert ULCL/BP to optimize the path of local business access according to the DNS response message. It can ensure that the terminal device can obtain the IP address of the application nearby at the new location, and it can also dynamically insert ULCL/BP according to the service access to realize local offloading, optimize the service access path, and improve communication efficiency.
  • the first, the second, etc. are only used to indicate that multiple objects are different.
  • the first network element and the second network element are only used to indicate different network elements. It should not have any influence on the network element itself and the number, etc., and the above-mentioned first, second, etc. should not cause any limitation to the embodiments of the present application.
  • pre-defined can be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate related information in devices (for example, including terminal devices and network devices). There is no limitation on its specific implementation.
  • FIG. 20 shows a schematic block diagram of a communication device 1400 according to an embodiment of the present application.
  • the communication device 1400 may correspond to the first network element described in the above method 200, or may be a chip or component applied to the first network element, and The modules or units of the communication device 1400 are respectively used to execute the actions or processing procedures performed by the first network element in the above method 200.
  • the communication device 1400 may include: a communication unit 1410 and a processing unit 1420
  • the communication unit 1410 is configured to receive a domain name system DNS query request from a terminal device, the DNS query request includes a first domain name, and the DNS query request is used to request an Internet Protocol IP address corresponding to the first domain name.
  • the processing unit 1420 is configured to generate first request information, where the first request information includes location information of the terminal device and the first domain name.
  • the communication unit 1410 is further configured to send the first request information to the second network element.
  • the communication unit 1410 is further configured to: receive first response information sent by the second network element in response to the first request information, where the first response information includes the IP address.
  • the communication unit 1410 is further configured to send the IP address to the terminal device.
  • the communication device provided by the present application adds the location information of the terminal device to the DNS query request and sends the second network element, so that the second network element determines the IP of the application server corresponding to the location of the terminal device and the requested domain name address.
  • the communication device feeds back the IP address to the terminal device.
  • the terminal device can access the service nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the DNS query request further includes a destination address
  • the destination address is an address of a DNS server
  • the first request information further includes: the destination address
  • the communication device is a user plane function network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the communication unit 1110 is further configured to send first notification information to the session management network element, where the first notification information is used by the session management network element to select the first offload point and the first protocol data unit session anchor PSA for the terminal device.
  • the communication device is a session management network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the processing unit 1120 It is also used to select the first offload node and the first protocol data unit session anchor PSA for the terminal device according to any one of the first domain name, the destination address, and the IP address corresponding to the first domain name, the The destination address is the address of the DNS server.
  • the communication device is a user plane function network element
  • the second network element is any one of a policy control function network element, an application function network element, or a DNS server
  • the communication unit 1410 is further configured to: receive the location information of the terminal device sent by the session management network element.
  • the communication unit 1410 is further configured to: receive the first rule sent by the session management network element, where the first domain name, the destination address, and the IP corresponding to the first domain name Any one of the addresses meets the first rule, and the destination address is the address of the DNS server.
  • the location information of the terminal device includes the tracking area identifier TAI of the terminal device, the data network access identifier DNAI, the identification information of the fourth network element, or the first IP address At least one of, wherein the fourth network element includes a user plane function network element or a radio access network network element.
  • the first IP address points to the management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device.
  • the communication device 1400 may be the user plane function network element in the above method embodiment (for example, it may be an anchor user plane function network element PSA) or a session management network element (for example, SMF) , It may also be a chip used to implement the function of the session management network element or the function of the user plane function network element in the above method embodiment.
  • the communication device 1100 may correspond to SMF, UPF1, I-SMF or I-UPF in the methods 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, and 1300 according to the embodiments of the present application.
  • the communication device 1400 may include a unit for executing the method executed by the SMF, UPF1, I-SMF, or I-UPF in the method 400 to the method 1300 in FIG. 10 to FIG. 19.
  • each unit in the communication device 1400 and other operations and/or functions described above are used to implement the corresponding processes of the method 400 to the method 1300 in FIG. 10 to FIG. 19, respectively. It should be understood that the specific process for each unit to execute the foregoing corresponding steps has been described in detail in the foregoing method embodiment, and is not repeated here for brevity.
  • the communication unit 1410 may include a receiving unit (module) and a sending unit (module), configured to perform the steps of receiving information and sending information by the first network element in each of the foregoing method embodiments.
  • the communication device 1400 may further include a storage unit for storing instructions executed by the processing unit 1420 and the communication unit 1410.
  • the processing unit 1420, the communication unit 1410 and the storage unit are in communication connection, the storage unit stores instructions, the processing unit 1420 is used to execute the instructions stored in the storage unit, and the communication unit 1410 is used to perform specific signal transmission and reception under the driving of the processing unit 1420.
  • the communication unit 1410 may be a transceiver, an input/output interface, an interface circuit, or the like.
  • the storage unit may be a memory.
  • the processing unit 1420 may be implemented by a processor. As shown in FIG. 21, the communication device 1500 may include a processor 1510, a memory 1520, and a transceiver 1530.
  • the communication device 1400 shown in FIG. 20 or the communication device 1500 shown in FIG. 21 can implement the various embodiments of the foregoing method 200 and the steps performed by the first network element in the related embodiments in FIGS. 4 to 8.
  • the steps performed by SMF, UPF1, I-SMF, or I-UPF in method 400 to method 1000 in FIG. 10 to FIG. 19 may also be implemented.
  • FIG. 22 shows a schematic block diagram of a communication device 1600 according to an embodiment of the present application.
  • the communication device 1600 may correspond to the third network element described in the above method 300, or may be a chip or component applied to the third network element, and The modules or units of the communication device 1600 are respectively used to execute the actions or processes performed by the third network element in the above method 300.
  • the communication device 1600 may include: a communication unit 1610 and a processing unit 1620
  • the communication unit 1610 is configured to receive the first domain name and the location information of the terminal device.
  • the processing unit 1620 is configured to determine an IP address corresponding to the first domain name at least according to the first domain name and the location information of the terminal device, and the IP address corresponds to the location of the terminal device.
  • the communication unit 1610 is also used to: send the IP address.
  • the communication device provided in this application determines the IP address of the application server corresponding to both the location of the terminal device and the requested domain name based on the location of the terminal device and the requested domain name, and feeds back the IP address to the terminal device.
  • the terminal device can access services nearby through the application server. It avoids the problem of limited service or inaccessibility of part of the service when the terminal device accesses the service through the application server far away from the terminal device, and improves the quality of the terminal device to access the service.
  • the terminal device can access services nearby, the time delay for the terminal device to access services is reduced, and communication efficiency is improved.
  • the processing unit 1620 is further configured to determine an IP address corresponding to the first domain name according to the first domain name and location information of the terminal device.
  • the first information includes: at least one domain name, a deployment location of an application corresponding to each of the at least one domain name, and an IP address corresponding to the deployment location of the application, and the at least one domain name includes the first domain name.
  • the first information may also include the correspondence between the first IP address and the deployment location of the MEC platform or the deployment location of the application server.
  • the communication device is any one of a session management network element, a policy control function network element, an application function network element, or a DNS server, and the communication device stores the first information.
  • the communication device is a DNS server
  • the communication unit 1310 is further configured to receive the location information of the terminal device sent by the policy control function network element or the application function network element.
  • the communication device is a DNS server
  • the communication unit 1310 is specifically configured to: receive the second request information sent by the session management network element or the user plane function network element, the second request information Including the first domain name.
  • the second request information further includes location information of the terminal device.
  • the location information of the terminal device includes the tracking area identifier TAI of the terminal device, the data network access identifier DNAI, the identification information of the fourth network element, or the first IP address At least one of the first IP address points to a management platform where the application server corresponding to the first domain name is located, and the location of the management platform corresponds to the location of the terminal device.
  • the fourth network element includes a user plane function network element or a wireless access network network element.
  • the communication device 1600 may be any one of the policy control function network element, the application function network element, the session management network element, or the DNS server in the above method embodiment. It may also be a chip used to implement the function of the policy control function network element, the function of the application function network element, the function of the session management network element, or the function of the DNS server in the above method embodiment.
  • the communication device 1300 may correspond to the SMF, I-SMF, PCF, AF or DNS server in the methods 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, and 1300 according to the embodiments of the present application .
  • the communication device 1600 may include a unit for executing the method executed by the SMF, I-SMF, PCF, AF, or DNS server in the method 400 to the method 1300 in FIG. 10 to FIG. 19.
  • the units in the communication device 1600 and the other operations and/or functions described above are used to implement the corresponding processes of the method 400 to the method 1300 in FIGS. 10 to 19. It should be understood that the specific process for each unit to execute the foregoing corresponding steps has been described in detail in the foregoing method embodiment, and is not repeated here for brevity.
  • the communication unit 1610 may include a receiving unit (module) and a sending unit (module) for performing the steps of receiving and sending information by the third network element in each of the foregoing method embodiments.
  • the communication device 1600 may further include a storage unit for storing instructions executed by the processing unit 1620 and the communication unit 1610.
  • the processing unit 1620, the communication unit 1610 and the storage unit are in communication connection, the storage unit stores instructions, the processing unit 1620 is used to execute the instructions stored in the storage unit, and the communication unit 1610 is used to perform specific signal transceiving under the driving of the processing unit 1620.
  • the communication unit 1610 may be a transceiver, an input/output interface, an interface circuit, or the like.
  • the storage unit may be a memory.
  • the processing unit 1620 may be implemented by a processor. As shown in FIG. 23, the communication device 1700 may include a processor 1710, a memory 1720, and a transceiver 1730.
  • the communication device 1600 shown in FIG. 22 or the communication device 1700 shown in FIG. 23 can implement each embodiment of the foregoing method 300 and the steps performed by the third network element in the related embodiment in FIG. 9.
  • the steps performed by the SMF, I-SMF, PCF, AF, or DNS server in the methods 400 to 1300 in FIG. 10 to FIG. 19 may also be implemented.
  • each unit in the above device can all be implemented in the form of software called by processing elements; they can also be implemented in the form of hardware; part of the units can be implemented in the form of software called by the processing elements, and some of the units can be implemented in the form of hardware.
  • each unit can be a separately established processing element, or it can be integrated in a certain chip of the device for implementation.
  • it can also be stored in the memory in the form of a program, which is called and executed by a certain processing element of the device.
  • the processing element may also be called a processor, and may be an integrated circuit with signal processing capability.
  • each step of the above method or each of the above units may be implemented by an integrated logic circuit of hardware in a processor element or implemented in a form of being called by software through a processing element.
  • the unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, for example: one or more application specific integrated circuits (ASIC), or, one or Multiple digital signal processors (digital signal processors, DSP), or, one or more field programmable gate arrays (FPGA), or a combination of at least two of these integrated circuits.
  • ASIC application specific integrated circuits
  • DSP digital signal processors
  • FPGA field programmable gate arrays
  • the unit in the device can be implemented in the form of a processing element scheduler
  • the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call programs.
  • CPU central processing unit
  • these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).
  • An embodiment of the present application also provides a communication system.
  • the communication system includes: the foregoing first network element and the foregoing second network element.
  • the communication system further includes the foregoing terminal device, third network element, or access One or more of network equipment.
  • the communication system includes the aforementioned third network element and the first network element.
  • the communication system further includes one or more of the aforementioned terminal device, second network element, or access network equipment.
  • the embodiment of the present application also provides a computer-readable storage medium for storing computer program code.
  • the computer program includes instructions for executing the methods 200 to 1300 of the domain name system query in the embodiments of the present application.
  • the readable medium may be a read-only memory (ROM) or a random access memory (RAM), which is not limited in the embodiment of the present application.
  • the computer program product includes an instruction.
  • the execution of the first network element, the second network element, the third network element, or the session management network element corresponds to Operation of the first network element, the second network element, or the third network element in the foregoing method.
  • the embodiment of the present application also provides a chip located in a communication device.
  • the chip includes a processing unit and a communication unit.
  • the processing unit may be a processor, for example, and the communication unit may be an input/output interface, a pin, or Circuit etc.
  • the processing unit can execute computer instructions to enable the communication device to execute any of the domain name system query methods provided in the foregoing embodiments of the present application.
  • the computer instructions are stored in a storage unit.
  • the storage unit is a storage unit in the chip, such as a register, a cache, etc.
  • the storage unit may also be a storage unit in the terminal located outside the chip, such as a read-only memory (ROM).
  • ROM read-only memory
  • RAM random access memory
  • the processor mentioned in any one of the above may be a CPU, a microprocessor, an ASIC, or one or more integrated circuits used to control the execution of the program of the above feedback information transmission method.
  • the processing unit and the storage unit can be decoupled, respectively set on different physical devices, and connected in a wired or wireless manner to realize the respective functions of the processing unit and the storage unit, so as to support the system chip to implement the above-mentioned embodiments Various functions in.
  • the processing unit and the memory may also be coupled to the same device.
  • the memory in the embodiment of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory may be ROM, programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), electrically erasable programmable read-only memory (electrically EPROM) , EEPROM) or flash memory.
  • Volatile memory can be RAM, which acts as an external cache.
  • RAM static RAM
  • dynamic RAM dynamic RAM
  • synchronous dynamic random access memory synchronous DRAM, SDRAM
  • double data rate Synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM
  • enhanced synchronous dynamic random access memory enhanced SDRAM, ESDRAM
  • synchronous link dynamic random access memory direct memory bus random access Access memory
  • direct rambus RAM direct rambus RAM
  • system and “network” in this article are often used interchangeably in this article.
  • and/or in this article is only an association relationship describing associated objects, which means that there can be three relationships, for example, A and/or B, which can mean: A alone exists, A and B exist at the same time, exist alone B these three situations.
  • the character "/" in this text generally indicates that the associated objects before and after are in an "or” relationship.
  • uplink and downlink appearing in this application are used to describe the direction of data/information transmission in a specific scenario.
  • the "uplink” direction generally refers to the direction or distribution of data/information from the terminal to the network side.
  • the “downlink” direction generally refers to the direction in which data/information is transmitted from the network side to the terminal, or the direction from the centralized unit to the distributed unit.
  • uplink and downlink “It is only used to describe the direction of data/information transmission.
  • the specific start and end equipment of the data/information transmission is not limited.
  • the methods in the embodiments of the present application may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software When implemented by software, it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer programs or instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer program or instruction may be stored in a computer-readable storage medium, or transmitted through the computer-readable storage medium.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server integrating one or more available media.
  • the disclosed system, device, and method may be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components can be combined or It can be integrated into another system, or some features can be ignored or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
  • each unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium.
  • the technical solution of this application essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a readable storage medium , Including several instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in each embodiment of the present application.
  • the aforementioned readable storage media include: U disk, mobile hard disk, read-only memory (read-only memory, ROM), random access memory (random access memory, RAM), magnetic disks or optical disks, etc., which can store program codes. Medium.

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Abstract

本申请提供了一种域名系统查询的方法和通信装置，该方法包括：第一网元接收来自于终端装置的DNS查询请求，DNS查询请求包括第一域名，DNS查询请求用于请求第一域名对应的IP地址；第一网元向第二网元发送第一请求信息，第一请求信息包括终端装置的位置信息以及第一域名；第二网元根据第一请求信息，确定与第一域名和终端装置的位置对应的IP地址并反馈给第一网元，第一网元向终端装置发送IP地址。本申请提供的方法，终端装置在进行域名查询时，核心网网元结合终端装置的位置信息以及查询的域名，确定对应的应用服务器的IP地址。使得终端装置获取与自己位置最近的应用服务器的IP地址并就近访问业务，提高了终端装置访问业务效率。

Description

域名系统查询的方法和通信装置
本申请要求分别于2019年08月20日和2019年09月27日提交中国专利局、申请号为201910770920.4、201910926424.3、申请名称为“域名系统查询的方法和通信装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，更为具体的，涉及一种域名系统查询的方法和通信装置。
背景技术
随着移动终端(例如手机)用户数量的不断增长，各类移动终端支持的业务功能不断增加，例如即时通信、证券、网页浏览、文件下载等功能已逐步成为终端装置，尤其是智能手机的主流应用。在上网过程中，终端装置需要对统一资源定位符(uniform resource locator，URL)的域名查询其域名对应的互联网协议(internet protocol，IP)地址，以便发送数据包。这个过程需要通过查询域名系统(domain name system，DNS)服务器才能完成。
终端装置可以向DNS服务器发送域名解析请求，该域名解析请求携带该域名，由DNS服务器返回该域名对应的互联网协议(internet protocol，IP)地址，终端装置可以通过该IP地址访问该域名。
移动边缘计算(mobile edge computing，MEC)是基于第五代(5rd generation，5G)演进架构，将接入网与互联网业务深度融合的一种技术。它将应用服务器(application server，AS)和移动宽带(mobile broadband，MBB)核心网部分业务处理和资源调度的功能一同部署到靠近接入网的网络边缘，通过业务靠近用户处理，来提供可靠、超低时延的极致业务体验。在目前的DNS查询中，终端装置将域名解析请求(DNS查询请求)通过连接MEC平台的用户面功能(user plane funtion，UPF)网元发给DNS服务器。然而，由于部署在不同MEC平台上提供相同服务的应用服务器具有相同的域名，而这些应用服务器具有不同的IP地址，DNS服务器如何确定将距离终端装置最近的应用服务器的IP地址返回给终端装置以使得终端装置就近访问本地业务，是目前亟待解决的问题。此外，当DNS服务器将距离终端装置最近的应用服务器的IP地址返回给终端装置之后，如何实现把业务流量选择性的路由到应用服务器所在的MEC平台，也缺乏相应的解决方案。
发明内容
本申请提供了一种域名系统查询的方法和通信装置，终端装置在进行域名查询时，核心网网元会结合终端装置的位置信息以及查询的域名，确定对应的应用服务器的IP地址。该应用服务器的IP地址是与终端装置的位置和查询的域名均对应的。可以使得终端装置获取与自己位置最近的应用服务器的IP地址并就近访问业务，提高了终端装置访问业务 效率。降低了终端装置访问业务的时延，提高了通信效率。
第一方面，提供了一种域名系统查询的方法，该方法的执行主体既可以是第一网元也可以是应用于第一网元的芯片。示例性的，第一网元可以是用户面功能网元或者为会话管理网元。以执行主体为第一网元为例，该方法包括：第一网元接收来自于终端装置的域名系统DNS查询请求，该DNS查询请求包括第一域名，该DNS查询请求用于请求该第一域名对应的互联网协议IP地址；该第一网元向第二网元发送第一请求信息，该第一请求信息包括该终端装置的位置信息以及该第一域名；该第一网元接收该第二网元发送的响应于该第一请求信息的第一响应信息，该第一响应信息包括该IP地址；该第一网元向该终端装置发送该IP地址。
第一方面提供的域名系统查询的方法，第一网元将终端装置的位置信息添加到DNS查询请求中发送第二网元，第二网元根据终端装置的位置信息以及请求的域名，确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
在第一方面的一种可能的实现方式中，该DNS查询请求还包括目的地址，该目的地址为DNS服务器的地址，该第一请求信息还包括：该目的地址。
在第一方面的一种可能的实现方式中，该第一网元为用户面功能网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该方法还包括：该第一网元向会话管理网元发送第一通知信息，该第一通知信息用于该会话管理网元为该终端装置选择第一分流节点或者第一协议数据单元会话锚点PSA，或者，第一通知信息用于会话管理网元确定终端装置的位置信息。该第一通知信息包括该第一域名、与该第一域名对应的IP地址、目的地址(DNS服务器的地址)中的一种或者多种。在该实现方式中，提高用户面功能网元向会话管理网元发送通知信息的准确性。防止了通信资源的浪费，提高通信的效率
在第一方面的一种可能的实现方式中，该第一网元为会话管理网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该方法还包括：该第一网元根据该第一域名、目的地址、与该第一域名对应的该IP地址中的任意一种，为该终端装置选择第一分流节点或者第一协议数据单元会话锚点PSA，该目的地址为该DNS服务器的地址。在该实现方式中，在插入分流节点和PSA之后。终端装置便可以通过该PSA去访问与第一域名对应的应用服务器。可以优化数据传输路线，降低数据传输时延，提高数据传输的效率。
在第一方面的一种可能的实现方式中，该第一网元为用户面功能网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该方法还包括：该第一网元接收会话管理网元发送该终端装置的位置信息。在该实现方式中，可以降低第一网元获取终端装置的位置信息的复杂度，容易实现，提高了获取到的终端装置的位置信息的准确性。
在第一方面的一种可能的实现方式中，该方法还包括：该第一网元接收会话管理网元 发送的第一规则，其中，该第一域名、目的地址、与该第一域名对应的该IP地址中的任意一种满足该第一规则，该目的地址为该DNS服务器的地址。在该实现方式中，提高用户面功能网元向会话管理网元发送通知信息的准确性，降低了用户面功能网元通知会话管理网元的时延，可以降低信令的开销。提高资源的利用率。
在第一方面的一种可能的实现方式中，该终端装置的位置信息包括该终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息或者第一IP地址中的至少一种。其中，DNAI用来标识第一域名对应的应用服务器的位置，或者该数据网络接入标识DNAI用来标识第一域名对应的应用服务器所在的管理平台的位置。该第四网元包括用户面功能网元或者无线接入网网元，该用户面功能网元为连接第一域名对应的应用服务器所在的管理平台的用户面功能网元。该用户面功能网元可以访问第一域名对应的应用服务器所在的管理平台。该无线接入网网元为终端装置当前接入的无线接入网网元。该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与终端装置的位置对应。
在该实现方式中，可以提高终端装置位置信息的准确性，使得该位置信息更加精确的反映出终端装置的实际位置。
第二方面，提供了一种域名系统查询的方法，该方法的执行主体既可以是第三网元也可以是应用于第三网元的芯片。示例性的，第一网元可以为策略控制功能网元、应用功能网元、会话管理网元或者DNS服务器中的任意一种。以执行主体为第三网元为例，该方法包括：第三网元接收第一域名和终端装置的位置信息，该第三网元至少根据该第一域名、该终端装置的位置信息，确定与该第一域名对应的IP地址，该IP地址与该终端装置的位置对应，
第二方面提供的域名系统查询的方法，第三网元根据终端装置的位置和请求的域名，确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
在第二方面的一种可能的实现方式中，该第三网元至少根据该第一域名、该终端装置的位置信息，确定与该第一域名对应的IP地址，包括：该第三网元根据该第一域名、该终端装置的位置信息以及第一信息确定该IP地址，其中，该第一信息包括：至少一个域名、与该至少一个域名中的每个域名对应的应用的部署位置、该应用的部署位置对应的IP地址，可选的，第一信息还可以包括第一IP地址与MEC平台的部署位置或者应用服务器的部署位置之间的对应关系。该至少一个域名包括该第一域名；该第三网元发送该IP地址。
在第二方面的一种可能的实现方式中，该第三网元为会话管理网元、策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该第三网元存储该第一信息。在该实现方式中，通过第三网元存储该第一信息，使得第三网元快速准确的确定出与终端装置的位置和请求的域名均对应的应用服务器的IP地址。提高了第三网元确定该IP地址的效率。
在第二方面的一种可能的实现方式中，该第三网元为DNS服务器，该方法还包括： 该第三网元接收策略控制功能网元或者应用功能网元发送的该终端装置的位置信息。
在第二方面的一种可能的实现方式中，该第三网元为DNS服务器，该第三网元接收第一域名，包括：该第三网元接收会话管理网元或者用户面功能网元发送的第二请求信息，该第二请求信息包括该第一域名。
在第二方面的一种可能的实现方式中，该第二请求信息还包括该终端装置的位置信息。
在第二方面的一种可能的实现方式中，该终端装置的位置信息包括该终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息或者第一IP地址中的至少一种。其中，该数据网络接入标识DNAI用来标识第一域名对应的应用服务器的位置，或者该数据网络接入标识DNAI用来标识第一域名对应的应用服务器所在的管理平台的位置。该第四网元包括用户面功能网元或者无线接入网网元，该用户面功能网元为连接第一域名对应的应用服务器所在的管理平台的用户面功能网元。该用户面功能网元可以访问第一域名对应的应用服务器所在的管理平台。该无线接入网网元为终端装置当前接入的无线接入网网元。该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与终端装置的位置对应。
第三方面，提供了一种域名系统查询的方法，该方法包括：会话管理网元从策略控制功能网元或者应用功能网元接收第二信息，该第二信息包括至少一个域名以及至少一个域名中的每个域名对应的应用服务器的位置信息；该会话管理网元根据该第二信息以及终端装置发送的第一域名确定该第一域名对应的应用服务器的位置信息，该至少一个域名包括该第一域名。
第三方面提供的域名系统查询的方法，会话管理网元根据获取的第二信息，以及接收到的第一域名，确定与第一域名对应的应用服务器的位置信息。以便于会话管理网元或者DNS服务器根据应用服务器的位置信息确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。
在第三方面的一种可能的实现方式中，该方法还包括：该会话管理网元将该第一域名对应的应用服务器的位置信息发送至DNS服务器；
该第一域名对应的应用服务器的位置信息用于该DNS服务器确定该第一域名对应的应用服务器的IP地址。
在第三方面的一种可能的实现方式中，该第一域名对应的应用服务器的位置信息包括DNAI或者第一IP地址；该第一IP地址指向第一域名对应的应用服务器的位置。
在第三方面的一种可能的实现方式中，该第二信息还包括至少一个域名中的每个域名对应的应用服务器的IP地址。该方法还包括：该会话管理网元根据该第二信息确定该第一域名对应的应用服务器的IP地址；该会话管理网元将该IP地址发送至该终端装置。
第四方面，提供了一种通信装置，该装置包括用于执行以上第一方面或第一方面的任意可能的实现方式中各个步骤的单元。
第五方面，提供了一种通信装置，该装置包括用于执行以上第二方面或第二方面的任意可能的实现方式中各个步骤的单元。
第六方面，提供了一种通信装置，该装置包括用于执行以上第三方面或第三方面的任意可能的实现方式中各个步骤的单元。
在一种设计中，该通信装置为通信芯片，通信芯片可以包括用于发送信息或数据的输入电路或者接口，以及用于接收信息或数据的输出电路或者接口。
在另一种设计中，该通信装置为通信设备(例如，终端设备或接入网设备或者核心网设备)，通信芯片可以包括用于发送信息或数据的发射机，以及用于接收信息或数据的接收机。
第七方面，提供了一种通信装置，该装置包括至少一个处理器和存储器，该至少一个处理器获取存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第一方面或第一方面的任意可能的实现方式中的方法。
第八方面，提供了一种通信装置，该装置包括至少一个处理器和存储器，该至少一个处理器获取存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第二方面或第二方面的任意可能的实现方式中的方法。
第九方面，提供了一种通信装置，该装置包括至少一个处理器和存储器，该至少一个处理器获取存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第三方面或第三方面的任意可能的实现方式中的方法。
第十方面，提供了一种通信装置，该装置包括至少一个处理器和接口电路，该接口电路用于该至少一个处理器获取至少一个存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第一方面或第一方面的任意可能的实现方式中的方法。
第十一方面，提供了一种通信装置，该装置包括至少一个处理器和接口电路，该接口电路用于该至少一个处理器获取至少一个存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第二方面或第二方面的任意可能的实现方式中的方法。
第十二方面，提供了一种通信装置，该装置包括至少一个处理器和接口电路，该接口电路用于该至少一个处理器获取至少一个存储器中的程序或指令，该至少一个处理器用于执行该程序或指令以使该通信装置执行以上第三方面或第三方面的任意可能的实现方式中的方法。
第十三方面，提供一种处理器，包括：输入电路、输出电路和处理电路。该处理电路用于通过该输入电路接收信号，并通过该输出电路发射信号，使得该处理器执行第一方面至第三方面，或第一方面至第三方面中的任一方面中的各实现方式中的方法。
在具体实现过程中，上述处理器可以为芯片，输入电路可以为输入管脚，输出电路可以为输出管脚，处理电路可以为晶体管、门电路、触发器和各种逻辑电路等。输入电路所接收的输入的信号可以是由例如但不限于接收器接收并输入的，输出电路所输出的信号可以是例如但不限于输出给发射器并由发射器发射的，且输入电路和输出电路可以是同一电路，该电路在不同的时刻分别用作输入电路和输出电路。本申请实施例对处理器及各种电路的具体实现方式不做限定。
第十四方面，提供了一种用户面功能网元或者为会话管理网元，该户面功能网元或者会话管理网元包括：上述第七方面提供的通信装置，或者，上述第九方面提供的通信装置， 或者，上述第十一方面提供的通信装置。
第十五方面，提供了一种策略控制功能网元、应用功能网元、会话管理网元或者DNS服务器，该策略控制功能网元、应用功能网元、会话管理网元或者DNS服务器包括：上述第八方面提供的通信装置，或者，上述第十方面提供的通信装置，或者，上述第十二方面提供的通信装置。
第十六方面，提供了一种通信系统，包括：上述的第七方面提供的通信装置和上述的第八方面提供的通信装置，或者，上述第九方面提供的通信装置和上述第十方面提供的通信装置，或者，上述第十一方面提供的通信装置和上述第十二方面提供的通信装置，或者，上述第十四方面提供的网元和上述第十五方面提供的网元。
在一个可能的设计中，该通信系统还可以包括本申请实施例提供的方案中的终端装置和/或接入网设备。
第十七方面，提供了一种计算机程序产品，该计算机程序产品包括计算机程序，该计算机程序在被处理器执行时，用于执行第一方面或第一方面的任意可能的实现方式中的方法，或者执行第二方面或第二方面的任意可能的实现方式中的方法，或者执行第三方面或第三方面的任意可能的实现方式中的方法。
第十八方面，提供一种计算机可读存储介质，该计算机可读存储介质中存储有计算机程序，当该计算机程序被执行时，用于执行第一方面或第一方面的任意可能的实现方式中的方法，或者执行第二方面或第二方面的任意可能的实现方式中的方法，或者执行第三方面或第三方面的任意可能的实现方式中的方法。
根据本申请提供的方案，终端装置在进行域名查询时，核心网网元会结合终端装置的位置信息以及查询的域名，确定对应的应用服务器的IP地址。该应用服务器的IP地址是与终端装置的位置和查询的域名均对应的。可以使得终端装置获取与自己位置最近的应用服务器的IP地址并就近访问业务，提高了终端装置访问业务效率。降低了终端装置访问业务的时延，提高了通信效率。
附图说明
图1是一例适用于本申请实施例的无线通信系统的架构示意图。
图2是又一例适用于本申请实施例的无线通信系统的架构示意图。
图3是一例终端装置在会话初始建立完成之后的域名访问过程的示意图。
图4是本申请实施例提供的一例域名系统查询的方法的示意性交互图。
图5是本申请实施例提供的另一例域名系统查询的方法的示意性交互图。
图6是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图7是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图8是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图9是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图10是本申请实施例提供的再一例域名系统查询的方法的示意性交互图。
图11是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图12是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图13是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图14是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图15是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图16是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图17是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图18是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图19是本申请实施例提供的又一例域名系统查询的方法的示意性交互图。
图20是本申请实施例提供的通信装置的示意图。
图21是本申请实施例提供的又一例通信装置的示意图。
图22是本申请实施例提供的通信装置的示意图。
图23是本申请实施例提供的又一例通信装置的示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
本申请实施例的技术方案可以应用于各种通信系统，例如：全球移动通讯(Global System of Mobile communication，GSM)系统、码分多址(Code Division Multiple Access，CDMA)系统、宽带码分多址(Wideband Code Division Multiple Access，WCDMA)系统、通用分组无线业务(General Packet Radio Service，GPRS)、长期演进(Long Term Evolution，LTE)系统、LTE频分双工(Frequency Division Duplex，FDD)系统、LTE时分双工(Time Division Duplex，TDD)、通用移动通信系统(Universal Mobile Telecommunication System，UMTS)、全球互联微波接入(Worldwide Interoperability for Microwave Access，WiMAX)通信系统、未来的第五代(5th Generation，5G)系统或新无线(New Radio，NR)等。
图1是适用于本申请的无线通信系统架构的示意性框图。如图1所示，该系统架构包括，终端装置，接入网设备，管理设备，网关设备以及数据网络(data network，DN)。其中，图1中的终端装置可以用于通过无线空口连接到运营商部署的接入网设备，继而通过网关设备连接到数据网络；接入网设备主要用于实现无线物理层功能、资源调度和无线资源管理、无线接入控制以及移动性管理等功能；管理设备主要用于终端装置的设备注册、安全认证、移动性管理和位置管理等，网关设备主要用于与终端装置间建立通道，在该通道上转发终端装置和外部数据网络之间的数据包；数据网络可对应于多种不同的业务域，例如IP多媒体子系统(IP multimedia subsystem，IMS)、互联网(Internet)、互联网协议电视(internet protocol television，IPTV)、其他运营商业务域等，主要用于为终端装置提供多种数据业务服务，其中可以包含例如服务器(包括提供组播业务的服务器)、路由器、网关等网络设备。对于希望接收IP组播业务数据包的终端，需要通过组管理协议请求加入/退出某组播业务对应的组播IP地址，以开始接收/结束所述组播业务，IP组播的组管理协议在IPv4中有网络组管理协议(internet group management protocol，IGMP)协议，对应在IPv6中有组播侦听者发现协议(multicast listener discovery protocol，MLD)协议。需要说明的是，图1仅为示例性架构图，除图1中所示功能单元之外，该网络架构还可以包括其他功能单元或功能网元，本申请实施例对此不进行限定。
当图1所示通信网络为5G网络时，上述终端装置(也可以称为终端装置)可以为用户设备(user equipment，UE)，如：手机、电脑，还可以为蜂窝电话、无绳电话、会话发 起协议(session initiation protocol，SIP)电话、智能电话、无线本地环路(wireless local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、电脑、膝上型计算机、手持式通信设备、手持式计算设备、卫星无线设备、无线调制解调器卡、电视机顶盒(set top box，STB)、用户驻地设备(customer premise equipment，CPE)和/或用于在无线系统上进行通信的其它设备。上述接入网设备可以为接入网(access network，AN)/无线接入网(radio access network，RAN)设备，由多个5G-AN/5G-RAN节点组成的网络，该5G-AN/5G-RAN节点可以为：接入节点(access point，AP)、下一代基站(NR nodeB，gNB)、中心单元(central unit，CU)和分布式单元(distributed unit，DU)分离形态的gNB、收发点(transmission receive point，TRP)、传输点(transmission point，TP)或某种其它接入节点。上述管理设备可以包括：统一数据管理网元(unified data management，UDM)、接入和移动性管理功能(access and mobility function，AMF)、会话管理功能(session management function，SMF)、策略控制功能(policy control function，PCF)、应用功能(application function，AF)等。网关设备可以包括用户面功能(user plane funtion，UPF)、分叉点(Branching Point，BP)、上行分类器(Uplink Classifier，UL CL)等功能单元，这些功能单元可以独立工作，也可以组合在一起实现某些控制功能，如：AMF、SMF和PCF可以组合在一起作为管理设备，用于完成终端装置的接入鉴权、安全加密、位置注册等接入控制和移动性管理功能，以及用户面传输路径的建立、释放和更改等会话管理功能，以及分析一些切片(slice)相关的数据(如拥塞)、终端装置相关的数据的功能。UPF作为网关设备主要完成用户面数据的路由转发等功能，如：负责对终端装置的数据报文过滤、数据传输/转发、速率控制、生成计费信息等。此外，在5G系统中为了支持把业务流量选择性的路由到数据网络，会话管理网元可以控制协议数据单元(protocol data unit，PDU)会话的数据路径，这样，PDU会话与数据网络之间就可以同时对应多个接口，即针对同一个PDU会话可以存在多个会话锚点。终结这些接口的用户面功能(user plane funtion，UPF)被称为PDU会话锚点(PDU session anchor，PSA)或者锚点UPF。PDU会话的每个锚点，还可以提供到相同DN的一个不同入口。同时，在接入网设备和不同PSA之间通过插入一个或者多个UPF网元实现到上行数据到不同PSA的数据分流，插入的UPF网元可以是分叉点(Branching Point，BP)或者上行分类器(uplink classifier，UL CL)。在此统一说明，BP或者UL CL还可以称为分流点UPF网元。
在图1的所示的5G网络中，各功能单元之间可以通过下一代网络(next generation，NG)接口建立连接实现通信，如：终端装置通过新无线(new radio，NR)接口与RAN设备建立空口连接，用于传输用户面数据和控制面信令；终端装置可以通过NG接口1(简称N1)与AMF建立控制面信令连接；AN/RAN设备例如下一代无线接入基站(NR NodeB，gNB)，可以通过NG接口3(简称N3)与分流点UPF建立用户面数据连接；AN/RAN设备可以通过NG接口2(简称N2)与AMF建立控制面信令连接；分流点UPF可以通过NG接口9(简称N9)与锚点UPF建立用户面数据连接；分流点UPF和锚点UPF可以通过NG接口4(简称N4)与SMF建立控制面信令连接；锚点UPF可以通过NG接口6(简称N6)与数据网络交互用户面数据；AMF可以通过NG接口11(简称N11)与SMF建立控制面信令连接；SMF可以通过NG接口7(简称N7)与PCF建立控制面信令连接。需要说明的是，图1所示的部分仅为示例性架构图，除图1所示的部分中所示功能单元之 外，该网络架构还可以包括其他功能单元或功能网元，本申请实施例对此不进行限定。
当图1所示通信网络为4G网络时，终端装置可参照图1中终端装置的相关描述，在此不再赘述；接入网设备可以为基站(nodeB，NB)、演进型基站(evolution nodeB，eNB)、TRP、TP、AP或某种其它接入单元；核心网设备可以包括：移动管理网元(mobility management entity，MME)、策略与计费规则功能(policy and charging rules function，PCRF)等管理设备，以及服务网关(serving gateway，SGW)、分组数据网络网关(packet data network gateway，PGW)、本地网关(local gateway，LGW)等网关设备。
应理解，本申请中的网元之间的接口名称仅是示例性的，网元之间的接口还可以是其他名称，本申请对接口的名称不予限。
本申请实施例中的终端装置可以指用户设备、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端、无线通信设备、用户代理或用户装置。终端装置还可以是蜂窝电话、无绳电话、会话启动协议(Session Initiation Protocol，SIP)电话、无线本地环路(Wireless Local Loop，WLL)站、个人数字处理(Personal Digital Assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备，未来5G网络中的终端装置或者未来演进的公用陆地移动通信网络(Public Land Mobile Network，PLMN)中的终端装置等，本申请实施例对此并不限定。
本申请实施例中的接入网设备可以是用于与终端装置和和核心网设备通信的设备，该接入网设备可以是全球移动通讯(Global System of Mobile communication，GSM)系统或码分多址(Code Division Multiple Access，CDMA)中的基站(Base Transceiver Station，BTS)，也可以是宽带码分多址(Wideband Code Division Multiple Access，WCDMA)系统中的基站(NodeB，NB)，还可以是LTE系统中的演进型基站(Evolutional NodeB，eNB或eNodeB)，还可以是云无线接入网络(Cloud Radio Access Network，CRAN)场景下的无线控制器，或者该接入网设备可以为中继站、接入点、车载设备、可穿戴设备以及未来5G网络中的网络设备或者未来演进的PLMN网络中的接入网设备等，本申请实施例并不限定。
随着移动终端(例如手机)用户数量的不断增长，各类移动终端支持的业务功能不断增加，例如即时通信、证券、网页浏览、文件下载等功能已逐步成为终端终端，尤其是智能手机的主流应用。在上网过程中，移动终端需要对统一资源定位符(uniform resource locator，URL)的域名查询其域名对应的互联网协议(internet protocol，IP)地址，以便发送数据包。这个过程需要通过查询域名系统(domain name system，DNS)服务器才能完成。
DNS服务器是一种分布式的主机信息数据库，提供域名和IP地址之间的映射和转换，可以通过DNS服务器将域名解析为对应的IP地址。终端装置可以通过DNS提供的域名解析服务实现对域名的访问。
域名访问的过程如下：以终端装置访问域名A为例，当终端装置访问该域名A时，查询其缓存中是否存在该域名A对应的应用服务器的IP地址，如果存在，则终端装置可以直接获取该IP地址，通过该IP地址访问该域名A。如果不存在，则终端装置可以向DNS服务器发送域名解析请求，该域名解析请求携带该域名A，由DNS服务器返回该域名A 对应的IP地址，终端装置可以通过该IP地址访问该域名A。
另外，终端装置在获得域名对应的IP地址后，生成并缓存一条DNS缓存记录。该DNS缓存记录用于表示域名与IP地址的对应关系。此外，终端装置针对缓存的每条DNS缓存记录维护相应的存留时间(time to live，TTL)。DNS缓存记录的TTL为该DNS缓存记录在终端装置的缓存中的保留的时间。这样，若在某一个DNS缓存记录的TTL内，终端装置需要再次访问该DNS缓存记录中的域名，则该终端装置可以直接根据该DNS缓存记录，获取该域名对应的IP地址。若超过该DNS缓存记录的TTL后，该终端装置需要再次访问该域名，通过DNS服务器解析得到所述域名对应的IP地址。
针对5G系统中的PDU会话，可以使用上行分类器(uplink classifier，ULCL)实现同一个PDU会话存在多个会话锚点，或者使用互联网协议第六版(Internet Protocol Version6，Ipv6)多归属(multi-homing)实现同一个PDU会话存在多个会话锚点。
在利用ULCL实现多PSA的PDU会话场景中，SMF可以在PDU会话的数据路径中间插入UL CL。UL CL是UPF提供的功能，旨在使用SMF提供的流过滤器，对某些业务进行本地流量路由(traffic routing)。其中，终端装置不感知UL CL也不参与UL CL的增删。UL CL基于SMF提供的业务检测和业务转发规则，把上行业务转发到不同的PDU会话锚点(例如图1中UPF1和UPF2为PDU会话两个不同的锚点)。并且聚合去往终端装置的下行数据流，即：把来自不同PDU会话锚点(例如图1中UPF1和UPF2)的业务数据流聚合到去往终端装置的下行链路。
在利用BP实现多PSA的PDU会话场景中，该PDU会话被称为多归属(multi-homing)PDU会话。multi-homing PDU会话能够通过多个PDU会话锚点(例如图1中UPF1和UPF2)接入DN。用户面数据在一个共同的UPF处产生分支，路由到不同的PDU会话锚点。支持这个功能的UPF称为分支点(Branching point，BP)。分支点把上行业务数据流转发到不同的PDU会话锚点，并且聚合去往终端装置的下行业务数据流，multi-homing仅适用于IPv6类型的PDU会话，且该PDU会话可以关联多个IPv6前缀。
ULCL/BP的插入可以在PDU会话初始建立过程中执行，或者在PDU会话初始建立完成之后的任意时刻执行。如果终端装置的PDU会话初始建立过程中没有插入ULCL/BP，那么该PDU会话初始建立时仅有一个会话锚点PSA，该PSA可以称为远端PSA，如图2所示，图2所示的为仅有远端PSA的无线通信系统架构的示意性框图。与图1不同之处在于，网关设备中只有一个UPF作为会话锚点，用于终端装置与数据网络等之间的通信。在PDU会话初始建立过程中，为了选择最佳的锚点UPF，核心网会参考终端装置的位置来选择PSA，但是由于终端装置具有移动性，远端PSA的位置不能代表终端装置当前所在的物理位置。在图2的基础上，图3为终端装置在会话初始建立完成之后的域名访问过程的示意图。如图3所示，假设在PDU会话初始建立过程中核心网为终端装置分配的地址为IP-3，当终端装置通过远端PSA请求DNS查询域名A时，远端PSA将终端装置的DNS查询请求(query)发送至DNS服务器。由于域名A对应的应用服务器可以有多个，分别部署在不同的位置。例如，域名A对应的应用服务器部署在两个不同的MEC平台上，即MEC平台-1和MEC平台-2。两个应用服务器的IP地址分别为IP-3A和IP-1。其中，地址为IP-3A的应用服务器部署在MEC平台-1上，MEC平台-1的部署位置与远端PSA最近。地址为IP-1的应用服务器部署在MEC平台-2上，MEC平台-2的部署位置与终端 装置的当前位置最近。由于DNS服务器不感知终端装置当前的位置，DNS服务从远端PSA接收来自终端装置的DNS查询请求之后，按照地址亲和性，并根据请求的域名A返回跟远端PSA“最近”的应用服务器的IP地址，因此DNS服务器返回MEC平台-1上部署的应用服务器的地址(如图3中的IP-3A)，这样终端装置就无法就近获取到与终端装置最近的MEC平台-2上部署的应用服务器的IP地址，导致终端装置无法通过MEC平台-2上部署的应用服务器就近访问业务，使得终端装置的访问的某些业务的服务受限或者访问不到部分业务。并且，由于终端装置只能通过远端应用服务器访问业务，增大了终端装置访问业务的时延，降低了通信效率。
有鉴于此，本申请提供了一种域名系统查询的方法，终端装置在进行域名查询时，核心网网元会结合终端装置的位置信息以及查询的域名，确定对应的应用服务器的IP地址。该应用服务器的IP地址是与终端装置的位置和查询的域名均对应的。可以使得终端装置获取与自己位置最近的应用服务器的IP地址并就近访问业务，提高了终端装置访问业务效率。降低了终端装置访问业务的时延，提高了通信效率。
下面结合图4详细说明本申请提供的域名系统查询的方法，图4是本申请一个实施例的域名系统查询的方法200的示意流程图。以第一网元和第二网元为执行主体说明书本申请提供的方法。作为示例而非限定，执行方法的执行主体也可以是应用于第一网元和第二网元的芯片。
该方法200可以应用在图1和图2所示的场景中，当然也可以应用在其他通信场景中，本申请实施例在此不作限制。
如图4所示，图4中示出的方法200可以包括S210至S250。图4的实施例中的技术特征的解释也可参考本申请说明书其它实施例的相关部分。下面结合图4详细说明方法200中的各个步骤。
S210，第一网元接收来自于终端装置的域名系统DNS查询请求，该DNS查询请求包括第一域名，该DNS查询请求用于请求该第一域名对应的互联网协议IP地址。可选的，该DNS查询请求还包括目的地址，该目的地址可以为DNS服务器的地址。其中，第一域名可以是完全限定域名(fully qualified domain name，FQDN)，例如，一台机器主机名(hostname)是www，域后缀(domain)是test.com，那么该主机的域名FQDN应该是 www.test.com。第一域名还可以是其他形式的域名，本申请不做限定。
S220该第一网元向第二网元发送第一请求信息，该第一请求信息包括该终端装置的位置信息以及该第一域名。可选的，该第一请求信息还包括该目的地址。其中，第一请求信息的类型可以是包括该终端装置的位置信息以及该第一域名的DNS查询请求消息。
S230，第二网元根据该第一请求信息，确定与该第一域名和该终端装置的位置对应的互联网协议IP地址。
S240，第二网元向第一网元发送响应于第一请求信息第一响应信息，该第一响应信息包括与第一域名对应的应用服务器的IP地址，该应用服务器的IP地址与还与该终端装置的位置对应，即该IP地址是终端装置当前能访问的本地应用服务器的IP地址。相应的，第一网元接收该第一响应信息。其中，第一响应信息的类型可以是包括该应用服务器的IP地址的DNS响应消息。
S250，第一网元向该终端装置发送该IP地址。
在S210中，终端装置需要进行DNS查询时，会向核心网设备发送DNS查询请求(也可以称为DNS报文)。该DNS查询请求包括终端装置需要查询的第一域名。该DNS查询请求用于请求该第一域名对应的IP地址。第一域名对应的IP地址可以理解为第一域名对应的应用(application)的IP地址，应用(application)的IP地址可以理解为应用服务器的IP或者应用实例的IP地址。具体的，终端装置可以通过接入网设备将DNS查询请求发送给核心网中的第一网元，第一网元可以是用户面功能网元(例如可以为锚点用户面功能网元PSA)或者为会话管理网元(例如为SMF)。该核心网设备可以是第一网元。如果第一网元为会话管理网元，终端装置可以先将DNS查询请求发送给用户面功能网元，用户面功能网元可以将该DNS查询请求转发给会话管理网元。这里的用户面功能网元可以理解为锚点用户面功能网元PSA。例如，在图2所示的架构图中，在终端装置的会话初始建立时，这个用户面功能网元相当于远端PSA。可选的，该DNS查询请求还包括目的地址，该目的地址为DNS服务器的地址(例如IP地址等)。即终端设备需要将该DNS查询请求最终发给该DNS服务器。
在S220中，第一网元接收到该DNS查询请求后，获取终端装置的位置信息，并将终端装置的位置信息添加到该DNS查询请求。进一步的，第一网元可以向第二网元发送第一请求信息，第一请求信息包括终端装置的位置信息以及该第一域名。第二网元可以是会话管理网元(例如SMF)、策略控制功能网元(例如PCF)、应用功能网元(例如为AF)或者DNS服务器中的任意一种。可选的，该第一请求信息还包括该目的地址。其中，第一请求信息的类型可以是包括终端装置的位置信息以及该第一域名的DNS查询请求消息。
例如，当第一网元为用户面功能网元时，第二网元可以是会话管理网元、策略控制功能网元、应用功能网元或者DNS服务器中的任意一种。此时，第一网元获取终端的位置信息可以是第一网元从会话管理网元或者其他网元获取终端的位置信息，本申请不做限定。又例如，当第一网元为会话管理网元时，第二网元可以为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，此时，第一网元获取终端的位置信息可以是第一网元从移动性管理网元或者其他网元获取终端的位置信息，本申请不做限定。其中，第一网元将终端装置的位置信息添加到该DNS查询请求的具体实现方法可以是，第一网元可以在DNS查询请求(DNS报文)选项中增添终端装置的位置信息。或者，由于传输控制协议(transmission control protocol，TCP)可以承载DNS报文，第一网元还可以在TCP选项(option)中增添终端装置的位置信息，本申请不做限定。此外，终端装置的位置信息可以通过单独的消息或包含在其它消息中发送。
可选的，作为一种实现方式，第一网元还可以将DNS查询请求消息发送到DNS服务器(server)之后，再将终端装置的位置信息发送至DNS服务器(server)，换句话说，第一网元可以将DNS查询请求消息和终端装置的位置信息分多条消息发送至DNS服务器，本申请不做限定。
具体的，终端装置的位置信息可以包括：终端装置的跟踪区域标识(tracking area identity，TAI)和/或第四网元的标识信息。第四网元的标识信息包括用户面功能网元(第四网元)的IP地址或者用户面功能网元(第四网元)的标识(identify，ID)。需要注意的是，这里的用户面功能网元指的是连接第一域名对应的应用服务器所在的管理平台的 UPF。可以理解为，该用户面功能网元可以访问第一域名对应的应用服务器所在的管理平台。第四网元的标识信息还可以是该终端装置接入的无线接入网(第四网元)的IP地址或者该终端装置接入的无线接入网(第四网元)的ID。可选的，终端装置的位置信息还可以包括终端装置当前能访问的第一域名对应的应用服务器所在的MEC平台的部署位置，或者终端装置当前能访问的MEC平台上部署的第一域名对应的应用服务器的部署位置。
在本申请的一些可能的实现方式中，在第三代合伙伙伴计划(3rd generation partnership project，3GPP)网络与MEC平台进行交互的时候，有可能在MEC平台的入口处部署了网络地址转换(network address translation，NAT)网关，通过NAT网关将内部网络IP地址替换为出口的IP地址提供公网可达性和上层协议的连接能力。例如，在图1所示的架构图中，假设UPF-1可以访问DNS服务器，UPF-2可以访问MEC平台。UPF-1可以为上述的第一网元，UPF-2可以为上述的第四网元。如果连接MEC平台的N6接口采用了NAT转换，在UPF-2的IP地址未经NAT转换前，UPF-2的IP地址是一个私有IP地址(或者私网IP地址)。如果第一网元直接将该私有IP地址发送第二网元(以DNS服务器为例说明)，DNS服务器并不理解该私有IP地址的含义，不能根据该私有IP确定终端装置的位置信息，即UPF-2的IP已经不能用于表征终端装置的位置信息。在这种情况下，DNS请求中添加的终端装置的位置信息应该是UPF-2的地址经过NAT转换后的公网IP地址(即N6接口经过NAT转换后的IP地址)，这样DNS服务器才能根据该公网IP地址确定终端装置当前的位置信息。即终端设备的位置信息还可以包括第一IP地址，该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与终端装置的位置对应。可以理解为，该MEC平台部署了应用服务器。该应用服务器即为DNS查询请求用于请求的与第一域名对应的应用服务器。例如，UPF-2可以连接第一域名对应的应用(应用服务器)所在的管理平台，那么第一IP地址可以为上述的UPF-2的私网地址经过NAT转换后的公网IP地址(或者公有IP地址)。
也就是说，在MEC平台的入口处部署了NAT网关的情况下，第一网元需要将上述的UPF-2(第四网元)经过NAT转换后得到的公网IP地址发送给第二网元，以便于第二网元根据该公网IP地址确定终端装置的位置。即终端装置的位置信息还可以包括指向第一域名对应的应用所在的管理平台的IP地址。在S230中，第二网元会根据第一请求信息，确定与该第一域名和该终端装置的位置对应的IP地址。其中，第一域名可以对应部署在不同位置(例如不同的MEC平台)的多个应用服务器，应用服务器的部署位置可以用MEC平台的标识来表示，其中，MEC平台的标识用于唯一标识一个MEC平台，例如，MEC平台的标识可以是部署在MEC平台上的UPF网元支持的数据网络接入标识(data network access identity，DNAI)或者连接MEC平台的UPF网元支持的DNAI，本申请实施例不作具体限定。因此不同的DNAI可以表示不同的MEC平台，进而可以表示部署在不同MEC平台上的应用服务器的部署位置。多个应用服务器的部署位置中的第一应用服务器的部署位置(即第一DNAI)对应该终端装置的位置。也就是说，第一应用服务器是与终端装置的位置和终端装置请求的域名均对应的应用服务器。例如，第一应用服务器的部署位置是与终端装置的当前位置最接近的，或者说，第一应用服务器所在的MEC平台是与终端装置的当前位置最接近的。第一应用服务器的IP地址即为S210中终端装置请求 的IP地址。例如。结合图3所示的例子，第一域名假设为域名A，域名A对应的应用服务器部署在两个不同的MEC平台上，即MEC平台-1(MEC平台-1的部署位置用DNAI-1表示)和MEC平台-2(MEC平台-2的部署位置用DNAI-2表示)，这两个不同的MEC平台上部署的两个应用服务器的IP地址分别为IP-3A和IP-1。假设地址为IP-3A的应用服务器部署在MEC平台-1上，地址为IP-1的应用服务器部署在MEC平台-2上，而终端装置的当前位置距离MEC平台-2最近或者终端装置的当前位置对应的MEC平台的部署位置为DNAI-2，则第一应用服务器就是地址为IP-1的应用服务器。
在S240中，在第二网元确定了与该终端装置的位置和第一域名均对应的应用服务器的IP地址后。第二网元会将该应用服务器的IP地址发给第一网元。具体的，第二网元可以向第一网元发送响应于该第一请求信息的第一响应信息，该第一响应信息包括该IP地址。其中，第一响应信息的类型可以是包含应用服务器的IP地址的DNS响应消息。
在S250中，第一网元接收到该IP地址后，可以将该IP地址发送给终端装置。例如，如果第一网元为用户面功能网元，用户面功能网元通过接入网设备将该应用服务器的IP地址发送给终端装置；如果第一网元为会话管理网元，则会话管理网元将该应用服务器的IP地址发给用户面功能网元。用户面功能网元通过接入网设备将该应用服务器的IP地址发送给终端装置。终端装置便可以通过应用服务器的IP地址就近访问业务和数据。
本申请提供的域名系统查询的方法，第一网元将终端装置的位置信息添加到DNS查询请求中发送第二网元，第二网元根据终端装置的位置信息以及请求的域名，确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
作为一种可能的实现方式，以图5为例，在图4所示的方法步骤的基础上，该方法200中的S230:第二网元会根据第一请求信息，确定与该第一域名和该终端装置的位置对应的IP地址：包括S231。
S231，该第二网元根据终端装置的位置信息、该第一域名以及第一信息，确定该应用服务器的IP地址；其中，该第一信息包括：至少一个域名、与该至少一个域名中的每个域名对应的应用服务器的部署位置、该应用服务器的部署位置上所部署的应用服务器的IP地址信息，该至少一个域名包括该第一域名，其中，不同的应用服务器的部署位置终端装置不同。
图5中所示的S210、S220、S240和S250的描述可以参考上述的对这几个步骤的描述，为了简洁，这里不再赘述。
在上述的S231中，第二网元可以根据该终端装置的位置信息、该第一域名以及第一信息，确定应用服务器的IP地址。具体的，终端装置的位置信息可以包括：终端装置的TAI、DNAI、第四网元的标识信息或者第一IP地址中的至少一种。
其中，DNAI用来标识第一域名对应的应用服务器的位置，或者该DNAI用来标识第一域名对应的应用服务器所在的管理平台的位置。该第四网元包括用户面功能网元或者无线接入网网元，该用户面功能网元为连接第一域名对应的应用服务器所在的管理平台的 用户面功能网元，可以理解为，该用户面功能网元可以访问第一域名对应的应用服务器所在的管理平台。该无线接入网网元为终端装置当前接入的无线接入网网元。该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与终端装置的位置对应。应该理解的是，在本申请实例中，该管理平台的位置与终端装置的位置对应的具体含义可以包括以下两种：
1)如果部署了第一域名对应的应用服务器的管理平台的位置有多个，与终端装置的位置对应的管理平台可以是距离终端装置的位置最近的管理平台。
2)如果部署了第一域名对应的应用服务器的管理平台的位置有多个，但是考虑其他因素，如管理平台上的负载或者应用服务器的资源情况等等，与终端装置的位置对应的管理平台可以是除了考虑终端装置的位置信息之外，其他因素综合决定的管理平台。
第四网元的标识信息包括用户面功能网元(第四网元)的IP地址或者用户面功能网元(第四网元)的标识(identify，ID)。需要注意的是，当终端装置的PDU会话只存在一个锚点时，这里的用户面功能网元可以是连接该管理平台的PDU会话锚点或者与无线接入网设备连接的中间(intermediate)UPF；当终端装置的PDU会话存在多个锚点时，例如UL CL/BP场景，这里的用户面功能网元可以是访问该管理平台的UL CL或者BP，还可以是访问该管理平台的PDU会话锚点。第四网元的标识信息还可以是该终端接入的无线接入网(第四网元)的IP地址或者该终端接入的无线接入网(第四网元)的ID。该第一IP地址指向第一域名对应的应用服务器所在的管理平台。其中，该管理平台的位置与终端装置的位置对应。可选的，终端装置的位置信息还可以包括终端装置当前能访问的第一域名对应的应用服务器所在的MEC平台的部署位置(用DNAI标识)，或者与终端装置当前能访问的MEC平台上部署的第一域名对应的应用服务器的部署位置(用DNAI标识)。
应理解，在本申请的各个实施例中，根据终端装置的位置确定第一域名对应的应用服务器所在的管理平台，即该管理平台的位置是根据该终端装置的位置确定的，那么，用于标识该管理平台的DNAI、连接该管理平台的用户面功能网元的标识信息，或者指向该管理平台的IP地址均可以用来表示终端装置的位置信息。
还应理解，在本申请的各个实施例中，涉及的管理平台的位置或者应用服务器的位置均为与终端装置的当前位置对应。在本申请中涉及的管理平台、MEC管理平台、MEC平台的含义或者功能相同，均可以管理该多个应用，并能够为多个应用提供服务。
其中，终端装置的TAI与MEC平台的部署位置或者应用服务器的部署位置(例如DNAI)之间可以存在映射关系或者对应关系，该对应关系可以为一一对应关系。可以根据终端装置的TAI确定MEC平台的部署位置或者应用服务器的部署位置。第二网元可以获取并存储第一信息。第一信息可以包括：至少一个域名、与至少一个域名中的每个域名对应的应用服务器的部署位置、应用服务器的IP地址信息。可选的，第一信息还可以包括第一IP地址与MEC平台的部署位置或者应用服务器的部署位置之间的对应关系。该至少一个域名包括该第一域名。其中，不同的应用服务器的部署位置不同。在本申请实施例中，一个域名可以对应多个应用服务器(多个应用服务器的IP地址)。第二网元根据终端装置的位置信息，可以唯一确定MEC平台的部署位置或者应用服务器的部署位置。在同一个MEC平台上或者同一个应用服务器的部署位置上，可以部署多个域名对应的应用 服务器或者应用实例，但是与同一个域名对应的应用服务器或者应用实例只有一个，进一步的，第二网元可以根据第一域名，确定与第一域名对应的应用服务器的IP的地址。即上述确定与第一域名和终端装置的位置对应的IP地址。
下面将举例进行说明。表1为第一信息包括的内容的一个示例。如表1所示，第一信息包括两个应用(application)，分别对应两个域名：域名A和域名B。域名A对应两个应用服务器，假设两个应用服务器的IP地址分别为IP-3A和IP-1。两个应用服务器部署在不同位置，例如部署在不同的MEC平台。假设地址为IP-3A的应用服务器部署在MEC平台-1上，地址为IP-1的应用服务器部署在MEC平台-2上，终端装置所在的位置距离MEC平台-2较近，或者说，MEC平台-2靠近终端装置当前所在的位置。域名B对应一个应用服务器，说明只在一个位置或者MEC平台部署了该应用服务器，其域名B对应的应用服务器的IP地址为IP-3B，也部署在MEC平台-2。可选的。应用服务器部署位置或者应用服务器所在的MEC平台的部署位置可以利用数据网络接入标识(data network DN Access Identifier，DNAI)表征，不同的DNAI表示不同的MEC平台或者应用服务器的部署位置。假设部署在MEC平台-2的应用服务器利用DNAI2表示，部署在MEC平台-1的应用服务器利用DNAI1表示。
表1
Figure PCTCN2020110009-appb-000001
结合表1的例子，DNS查询请求中携带终端装置需要查询的域名A，假设终端装置的位置距离MEC平台-2较近。第一网元向第二网元发送的第一请求信息包括域名A和终端装置的位置信息。第二网元根据域名A，确定对应的应用服务器的IP地址为部署在MEC平台-1的IP-3A和部署在MEC平台-2的IP-1，这两个应用服务器对应的DNAI不同。第二网元进一步的根据终端装置的位置信息确定终端装置当前能访问的MEC平台的部署位置或者应用服务器部署位置，即确定出于终端装置当前位置对应的DNAI为DNAI2(即MEC平台-2)。这样就可以确定出与终端装置的位置和请求的域名均对应的应用服务器的IP地址为IP-1。从而将IP-1反馈给终端装置。
应理解，表1只是示例性的，不应该对本申请的实施例造成限制。例如，第一信息还可以包括更多的域名。与某一个域名对应的应用服务器的部署位置还可以是更多个，如MEC平台的部署位置还可以是更多个。某一个部署位置还可以部署更多个不同域名对应的应用服务器。应用服务器的部署位置除了利用上述的DNAI来表征之外，还可以利用其他的参数来表征等。本申请实施例在此不作限制。
在上述的实现方式中，通过第二网元根据终端装置的位置信息、终端装置请求的域名以及上述的第一信息，确定出与终端装置的位置和请求的域名均对应的应用服务器的IP地址。可以使得确定出的应用服务器的IP地址的更加准确，提高确定应用服务器的效率。
应理解，在本申请实施例中，如果第一网元是用户面功能网元，则用户面功能网元可以在发送第一请求信息之前，向会话管理网元请求终端装置的位置信息，并将该终端装置的位置信息添加到第一请求信息并发送给第二网元。如果第一网元是会话管理网元，则会话管理网元可以自行获取终端装置的位置信息，并将该终端装置的位置信息添加到第一请求信息中。
还应理解，第一网元向第二网元发送的第一请求信息中，也可以不包括终端装置的位置信息。在这种情况下，第二网元可以自行获取终端装置的位置信息，例如，如果第二网元为会话管理网元，则上述的第一请求信息中可以不包括终端装置的位置信息，会话管理网元可以自行获取终端装置的位置信息。例如，会话管理网元可以从AMF获取终端装置的TAI。同时，会话管理网元也可以向AMF订阅终端装置的TAI，这样当终端装置的位置发生了移动，AMF可以向会话管理网元提供终端装置当前所在的最新的TAI，这样会话管理网元可以基于终端装置的TAI确定终端装置的位置信息。又例如，假设第二网元为DNS服务器，DNS服务器可以接收应用功能网元(例如AF)发送的终端装置的位置信息。又例如，假设第二网元为应用功能网元，应用功能网元可以通过能力开放信息从核心网设备获取终端装置的位置信息。其中，终端装置的位置信息的具体描述参考S231，这里不再赘述
第二网元可以获取并存储第一信息。例如，如果第二网元会话管理网元，会话管理网元可以接收策略控制功能网元(例如PCF)或者应用功能网元(例如AF)发送的第一信息。具体而言，应用功能网元可以将第一信息存储在UDR里面，策略控制功能网元可以向UDR请求该第一信息并存储该第一信息。或者，会话管理网元可以向策略控制功能网元请求该第一信息并存储该第一信息。又例如，假设第二网元为DNS服务器，DNS服务器可以接收应用功能网元(例如AF)发送的第一信息。或者，第一信息也可以是预先配置在DNS服务器中。应理解，本申请实施例中第二网元获取第一信息的方式不作限制。
在本申请的一些可能的实现方式中，如果该第一网元为会话管理网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，以图6为例，在图4所示的方法步骤的基础上，该方法包括S241。
S241，该第一网元根据第一域名或者与该第一域名对应的IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。
图6中所示的S210至S250的描述可以参考上述的4和图5中对这几个步骤的描述，为了简洁，这里不再赘述。
在S241中，如果第一网元为会话管理网元(例如SMF)，第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种。在这种情况下，第一网元可以根据终端装置请求的第一域名，或者第二网元反馈的与第一域名对应的应用服务器的IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。在插入分流节点和PSA之后。终端装置便可以通过该PSA去访问与第一域名对应的应用服务器。可以优化数据传输路线，降低数据传输时延，提高数据传输的效率。
一种可能的实现方式为：会话管理网元可以上述的步骤S210之后就执行S241，即在接收到自于终端装置的域名系统DNS查询请求时，就根据DNS查询请求包括的第一域名，确定为该终端装置选择第一分流节点和第一PSA。SMF网元确定第一域名的方法可以是：SMF网元上可以提前预先配置域名列表，或者SMF网元从PCF网元接收接收策略消息，该策略消息包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元就确定该DNS查询请求中包含的域名为第一域名。例如，结合表1的例子，如果终端装置请求的第一域名为部署在MEC平台-2上的应用对应的域名，则会话管理网元可以根据该第一域名，为终端装置选择第一分流节点和第一协议数据单元会话锚点PSA，第一分流节点可以是上述的ULCL或者BP，第一PSA可以是一个UPF。
可选的，该DNS查询请求还可以包括目的地址，该目的地址可以为DNS服务器的地址。SMF还可以根据DNS查询请求包括的目的地址，确定为该终端装置选择第一分流节点和第一PSA，其中，该目的地址可以为DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。通过上述方法，终端装置便可以通过该PSA就近访问业务，优化数据传输路线，降低数据传输时延。SMF不用等到第二网元发送响应信息后进行插入ULCL或者BP，可以降低信令的开销。
另外一种可能实现方式为：会话管理网元可以根据S240中第二网元反馈的应用服务器的IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。在这种情况下，S241可以在S240之后执行，即在接收到第二网元反馈的第一响应信息后，根据第一响应信息中的IP地址为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。其中，SMF网元根据应用服务器的该IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA的方法可以是：SMF网元可以提前预先配置IP地址列表，或者SMF网元从PCF网元接收策略消息，该策略信息包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要第二网元反馈的应用服务器的IP地址属于该IP地址列表，那么SMF网元就根据该IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。例如，结合表1的例子，如果第一响应信息包括的IP地址为部署在MEC平台-2上的与第一域名对应的应用服务器的IP地址(IP-1)，则会话管理网元可以根据该IP地址，为终端装置选择第一分流节点和第一协议数据单元会话锚点PSA，第一分流节点可以是一个ULCL或者BP。通过根据第二网元反馈的第一响应信息携带的IP地址，为终端装置选择第一分流节点和第一PSA，可以提高插入的第一分流节点和第一PSA的准确性，避免为不必要的域名以及已经执行过插入分流节点和PSA的应用部署位置再次的插入分流节点和PSA，防止了通信资源的浪费，提高通信的效率。
例如，如表1所示的例子中，如果第二网元反馈的第一响应信息携带的IP地址为部署在MEC平台-2上并且与第一域名对应的应用服务器的IP地址(IP-1)。假设终端装置初始建立PDU会话时只有远端PSA，在终端装置获取部署在MEC平台-2上与第一域名对应的应用服务器的IP地址(IP-1)后，还是需要通过远端PSA去访问该应用服务器(假设为第一应用服务器)。数据传输的路线为：
Figure PCTCN2020110009-appb-000002
Figure PCTCN2020110009-appb-000003
而远端PSA和第一应用服务器一般是部署在不同的位置的，这样造成数据传输 的路径不优，导致数据传输时延较大。因此。会话管理网元选择第一分流节点和插入第一PSA。第一PSA的部署位置可以是靠近第一应用服务器的部署位置(MEC平台-2)，或者第一PSA可以部署在MEC平台-2上。会话管理网元可以利用ULCL或者BP的方式插入第一PSA(UPF)。在插入第一PSA之后。终端装置便可以通过新插入的第一PSA去访问第一应用服务器。数据传输的路线为：
Figure PCTCN2020110009-appb-000004
Figure PCTCN2020110009-appb-000005
可以优化数据传输路线，降低数据传输时延，提高数据传输的效率。
在本申请的另一些可能的实现方式中，如果该第一网元为网元为用户面功能网元，该第二网元为策略控制功能网元、会话管理网元、应用功能网元或者DNS服务器中的任意一种，以图7为例，在图4所示的方法步骤的基础上，该方法包括S242。
S242，该第一网元向会话管理网元发送第一通知信息，该第一通知信息包括该第一域名或者、该目的地址、与该第一域名对应的IP地址中的至少一种，该第一通知信息用于该会话管理网元为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。
在S242中，如果第一网元为用户面功能网元(例如UPF)，则第二网元为策略控制功能网元、会话管理网元、应用功能网元或者DNS服务器中的任意一种。在这种情况下，第一网元可以向会话管理网元发送第一通知信息，该第一通知信息包括该第一域名、与该第一域名对应的IP地址、目的地址(DNS服务器的地址)中的一种或者多种。该第一通知信息用于该会话管理网元为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA。
在S242中，一种可能的实现方式为：用户面功能网元根据终端装置请求的第一域名或者根据DNS查询请求包括的目的地址，向会话管理网发送第一通知信息。在这种情况下，S242可以在S210之后就执行，即只需要执行步骤S210，在接收到收到自于终端装置的域名系统DNS查询请求后，就根据DNS查询请求包括的第一域名或者目的地址，向会话管理网元发送第一通知信息，用于通知会话管理网元为终端装置选择第一分流节点和第一PSA。用户面功能网元确定向会话管理网元发送第一通知信息的方法可以是：在用户面功能网元向会话管理功能网元发送第一通知信息之前，用户面功能网元上可以提前预先配置第一规则，或者用户面功能网元从会话管理网元接收第一规则，当第一域名或者该目的地址满足第一规则时，用户面功能网元向会话管理网元发送第一通知信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，第一规则为用户面功能网元接收的DNS查询请求中包含的目的地址包含在该目的地址列表中，当满足第一规则，那么用户面功能网元就确定向会话管理网元发送第一通知信息。换句话说，如果用户面功能网元判断出DNS查询请求中包含的目的地址满足向会话管理网元发送第一通知信息的条件，那么，用户面功能网元就向会话管理网发送第一通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，第一规则为用户面功能网元接收的DNS查询请求中包含的域名包含在该域名列表中，当满足第一规则，那么用户面功能网元就确定该DNS查询请求中包含的域名为第一域名。换句话说，如果用户面功能网元判断出DNS查询请求中包含的第一域名满足向会话管理网元发送第一通知信息的条件，那么，用户面功能网元就向会话管理网发送第一通知信息，其中，该条件 可以是DNS查询请求中包含的第一域名是第一规则中包含的任意一个域名。例如，结合表1的例子，如果终端装置请求的第一域名为域名A，则用户面功能网元获取该域名后，可以直接向会话管理网元发送第一通知信息，不用等到第二网元发送响应信息后在向会话管理网元发送第一通知信息，降低了用户面功能网元通知会话管理网元的时延，可以降低信令的开销。提高资源的利用率。
在S242中，另一种可能的实现方式为：用户面功能网元可以根据S240中第二网元反馈的应用服务器的IP地址，向会话管理网发送第一通知信息。用户面功能网元确定向会话管理网发送第一通知信息的方法可以是：用户面功能网元可以提前预先配置第一规则，或者用户面功能网元从会话管理网元接收第一规则，当应用服务器的IP地址满足第一规则时，即该IP地址包含在地址列表中，用户面功能网元向会话管理网元发送第一通知信息。例如，第一规则还可以包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要第二网元反馈的应用服务器的IP地址属于该IP地址列表，那么用户面功能网元就根据该IP地址，向会话管理网发送第一通知信息。换句话说，如果用户面功能网元判断出第二网元反馈的应用服务器的IP地址满足向会话管理网元发送第一通知信息的条件，那么，用户面功能网元就向会话管理网发送第一通知信息，其中，该条件可以是应用服务器的IP地址是第一规则中包含的任意一个IP地址。在这种情况下，S242可以在S240之后就执行，即需要执行步骤S210、S220、S230以及S240。在接收到第二网元反馈的第一响应信息后，根据第一响应信息中的IP地址，向会话管理网元发送第一通知信息，用于通知会话管理网元为终端装置选择第一分流节点和第一PSA。例如，结合表1的例子，如果第一响应信息包括的IP地址为部署在MEC平台-2上并且与第一域名对应的应用服务器的IP地址(IP-1)，则用户面功能网元向会话管理网元发送第一通知信息该第一通知信息包括该IP地址。可以提高用户面功能网元向会话管理网元发送通知信息的准确性。防止了通信资源的浪费，提高通信的效率。会话管理网元可以根据上述的第一通知信息，为终端装置选择第一分流节点和第一PSA，具体的描述可以参考上述的S241的描述，为了简洁，这里不再赘述。
在本申请的一些可能的实现方式中，如果该第一网元为用户面功能网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，以图8为例，在图4所示的方法步骤的基础上，该方法包括S219。
S219，该第一网元接收会话管理网元发送该终端装置的位置信息。
具体而言，如果第一网元为用户面功能网元时，则在上述的S220之前，用户面功能网元可以先从会话管理网元获取终端装置的位置信息。例如，用户面功能网元可以接收会话管理网元(例如SMF)发送的终端装置的位置信息。从而可以将终端装置的位置信息添加到上述的第一请求信息中发送给第二网元，降低第一网元获取终端装置的位置信息的复杂度，容易实现，提高了获取到的终端装置的位置信息的准确性。
本申请提供的域名系统查询的方法，第一网元将终端装置的位置信息添加到DNS查询请求发送第二网元。第二网元根据终端装置的位置和请求的域名，确定出与终端装置的位置和域名均对应的应用服务器的IP地址并反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
图9是本申请另一个实施例的域名系统查询的方法300的示意流程图，该方法300可以应用在图1和图2所示的场景中，当然也可以应用在其他通信场景中，本申请实施例在此不作限制。
如图9所示，图9中示出的方法300可以包括S310至S330。下面结合图9详细说明方法300中的各个步骤。
S310，第三网元接收第一域名和终端装置的位置信息。
S320，该第三网元至少根据该第一域名、该终端装置的位置信息，确定与该第一域名对应的IP地址，该IP地址与该终端装置的位置对应。
S330，该第三网元发送该IP地址。
在S310中，终端装置需要进行DNS查询时，会向核心网设备发送DNS查询请求。该DNS查询请求包括终端装置需要查询的第一域名。具体的，终端装置可以通过接入网设备将DNS查询请求发送给用户面功能网元(例如可以为PSA)，例如在终端装置的会话初始建立时，这个用户面功能网元相当于远端PSA。用户面功能网元接收到DNS查询请求后，会将该第一域名发送给第三网元，第三网元可以为策略控制功能网元、应用功能网元、会话管理网元或者DNS服务器中的任意一种。例如，用户面功能网元可以将来自于终端装置的DNS查询请求转发给第三网元，DNS查询请求时，就根据DNS查询请求包括的第一域名。在S310中第三网元接收第一域名和终端装置的位置信息。终端装置的位置信息相关的描述可以参考上述的S231中的相关的描述，为了简洁，这里不再赘述。
第一域名和终端装置的位置信息可以是同一个网元发送给第三网元的，例如，如果第三网元为DNS服务器，则第一域名和终端装置的位置信息可以是会话管理网元或者用户面功能网元发送给DNS服务器。当然，第一域名和终端装置的位置信息可以是不同的网元分别发送给第三网元的。例如，如果第三网元为DNS服务器，则第一域名可以是会话管理网元或者用户面功能网元发送给DNS服务器，终端装置的位置信息可以是应用管理网元发送给DNS服务器。本申请在此不做限制。
在S320中，第三网元至少根据该第一域名、该终端装置的位置信息，确定与该第一域名对应的IP地址，该IP地址与该终端装置的位置对应。关于S320的具体过程可以参考上述对于S231的描述，为了简洁，这里不再赘述。
可选的，在S320中，第三网元根据还可以根据该第一域名、该终端装置的位置信息以及第一信息，确定与该第一域名对应的IP地址。其中，该第一信息包括：至少一个域名、与该至少一个域名中的每个域名对应的应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)、该应用的部署位置上的应用服务器的IP地址，该至少一个域名包括该第一域名。可选的，第一信息还可以包括第一IP地址与MEC平台的部署位置或者应用服务器的部署位置之间的对应关系。
在S330中，在第三网元确定了与该终端装置的位置和第一域名均对应的应用服务器的IP地址后。第三网元会将该应用服务器的IP地址发给终端装置。例如，假设第三网元为会话管理网元，会话管理网元可以将该应用服务器的IP地址先发送给用户面功能网元，用户面功能网元通过接入网设备将该应用服务器的IP地址发送给终端装置。可选的，用户面功能网元可以根据第三网元反馈的应用服务器的IP地址，向会话管理网发送第一通知信息，用于通知会话管理网元为终端装置选择第一分流节点和第一PSA。用户面功能网 元确定向会话管理网发送第一通知信息的方法可以参考上述的S242的描述，为了简洁，这里不再赘述。
又例如，假设第三网元为DNS服务器，DNS服务器可以将该应用服务器的IP地址先发送给用户面功能网元或者会话管理网元，通过用户面功能网元或者会话管理网元、接入网设备将该应用服务器的IP地址发送给终端装置。可选的，会话管理网元可以根据第三网元反馈的应用服务器的IP地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA，具体方法可以参考上述的S241的描述，为了简洁，这里不再赘述。本申请在第三网元将该应用服务器的IP地址发送给终端装置的具体过程不做限制。
本申请提供的域名系统查询的方法，通过第三网元根据终端装置的位置和请求的域名，确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
在本申请的一些可能的实现方式中，第三网元可以为会话管理网元、策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该第三网元存储该第一信息。
具体而言，第三网元可以获取并存储第一信息。例如，如果第三网元为会话管理网元，会话管理网元可以接收策略控制功能网元(例如PCF)或者应用功能网元(例如AF)发送的第一信息。如果第三网元为应用功能网元，应用功能网元可以将第一信息存储在UDR里面。如果第三网元为策略控制功能网元，策略控制功能网元可以向UDR请求该第一信息并存储该第一信息。又例如，假设第三网元为DNS服务器，DNS服务器可以接收应用功能网元(例如AF)发送的第一信息。或者，第一信息也可以是预先配置在DNS服务器中。应理解，本申请实施例中第三网元获取第一信息的方式不作限制。
在本申请的一些可能的实现方式中，如果该第三网元为会话管理网元，会话管理网元根据第一域名或者与该第一域名对应的IP地址，为该终端装置选择第一分流节点和第一PSA。会话管理网元一分流节点和第一PSA的过程可以参考上述的S241中的相关描述，为了简洁，这里不再赘述。
在本申请的一些可能的实现方式中，在S310中，如果该第三网元为DNS服务器，DNS服务器可以通过如下方式获取终端装置的位置信息：
该DNS服务器接收策略控制功能网元、应用功能网元或者会话管理网元发送的终端装置的位置信息。
具体而言，会话管理网元可以从AMF获取终端装置的位置信息。同时，会话管理网元也可以向AMF订阅终端装置的位置信息，这样当终端装置的位置发生了移动，AMF可以向会话管理网元提供终端装置当前所在的最新的位置信息。应用功能网元可以通过能力开放功能网元(network exposure function，NEF)从核心网设备获取终端装置的位置信息。策略控制功能网元可以从AMF处获取终端装置的位置信息。策略控制功能网元、应用功能网元或者会话管理网元可以将终端装置的位置信息发送给DNS服务器。可选的，DNS服务器可以从策略控制功能网元、会话管理网元或者应用功能网元获取终端装置的位置，进一步的根据终端装置的位置确定出该终端装置当前能访问的MEC平台的部署位 置或者应用服务器的部署位置。或者，DNS服务器可以直接从策略控制功能网元、会话管理网元或者应用功能网元获取该终端装置当前能访问的MEC平台的部署位置或者应用服务器的部署位置。通过DNS服务器接收策略控制功能网元、应用功能网元或者会话管理网元发送的终端装置的位置信息，可以使得DNS服务器获取的终端装置的位置信息比较准确。进一步提高DNS服务器确定与终端装置的位置和第一域名对应的IP地址的准确性和效率。
在本申请的另一些可能的实现方式中，在步骤S310中，如果该第三网元为DNS服务器，DNS服务器可以通过如下方式获取终端装置第一域名：
该第三网元接收会话管理网元或者用户面功能网元发送的第二请求信息，该第二请求信息包括该第一域名。
具体而言，终端装置需要进行DNS查询时，会向核心网设备发送DNS查询请求。该DNS查询请求包括终端装置需要查询的第一域名。可选的，该DNS查询请求还包括目的地址。该目的地址可以是DNS服务器的地址。该DNS查询请求用于请求该第一域名对应的IP地址。终端装置可以通过接入网设备将DNS查询请求发送给核心网中的用户面功能网元，用户面功能网元可以直接将根据该DNS查询请求，向DNS服务器发送第二请求信息，该第二请求信息包括该第一域名。可选的，用户面功能网元可以根据第一域名或者DNS查询请求中的目的地址，向会话管理网发送第一通知信息，用于通知会话管理网元为终端装置选择第一分流节点和第一PSA。用户面功能网元确定向会话管理网发送第一通知信息的方法可以参考上述的S242的描述，为了简洁，这里不再赘述。或者，用户面功能网元可以先将该DNS查询请求发送给会话管理网元，会话管理网元将根据该DNS查询请求，向DNS服务器发送第二请求信息，该第二请求信息包括该第一域名。可选的，会话管理网元可以根据第一域名或者DNS查询请求中的目的地址，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA，具体方法可以参考上述的S241的描述，为了简洁，这里不再赘述。
可选的，上述的第二请求信息还可以包括终端装置的位置信息。例如，如果上述的第二请求信息是用户面功能网元发送给DNS服务器的，则用户面功能网元可以在发送第二请求信息之前，向会话管理网元请求终端装置的位置信息，或者用户面功能网元已经预先获取到了终端装置的位置信息，例如在会话建立过程中，会话管理网元将终端装置的位置信息发送至用户面功能网元。用户面功能网元将该终端装置的位置信息添加到第二请求信息并发送给DNS服务器。如果第二请求信息是会话管理网元发送给DNS服务器的，则会话管理网元先获取终端装置的位置信息，并将该终端装置的位置信息添加到第二请求信息并发送给DNS服务器。其中，上述将终端装置的位置信息添加到该DNS查询请求的具体实现方法可以是在DNS查询请求(DNS报文)选项中增添终端装置的位置信息。或者，由于TCP可以承载DNS报文，还可以在TCP选项(option)中增添终端装置的位置信息，本申请不做限定。
下面将结合具体的例子说明本申请提供的域名系统查询的方法。
图10是本申请一个实施例的域名系统查询的方法400的示意性流程图，该方法400可以应用在图1所示的架构中。图10所示的流程主要描述了会话管理网元确定应用服务器的IP地址过程。其中包括会话管理网元自行确定应用服务器的IP地址过程和通过策略 控制功能网元或者应用功能网元确定应用服务器的IP地址过程。图10所示的例子中，会话管理网元以SMF为例、策略控制功能网元以PCF为例、应用功能网元以AF为例进行说明。
如图10所示，该方法400包括：
S401，AF将应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)通过网络开放功能(network exposure function，NEF)网元存储到UDR里面。进一步的，还可以将第一信息存储到DNS服务器。例如，第一信息的内容可以为上述的表1所示的内容。
S402，终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、单网络切片选择辅助信息(single network slice selection assistance information，S-NSSAI)和数据网络名称(data network name，DNN)等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF网元，并将该终端装置的永久标识、终端装置的位置信息)、PDU会话标识，S-NSSAI和DNN等参数发送给SMF网元。
其中，S402步骤中的终端装置的位置信息可以是TAI，或者该终端装置接入的无线接入网的IP地址或者该终端装置接入的无线接入网的ID。
S403，在该会话建立过程中，SMF调用PCF的服务化操作策略建立控制请求(Npcf_SMPolicy Control_Create Request)，请求从PCF获取该PDU会话相关的策略信息。
S404，PCF调用UDR的服务化操作请求(Nudr_DM_Query)，从UDR获取该终端装置签约的应用相关的信息，其中包含S401中的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系(即第一信息)。
S405，PCF将该应用服务器的部署位置、域名和应用服务器的IP地址生成策略计费控制规则(Policy and Charging Control rule，PCC rule)，通过服务化操作策略建立控制响应(Npcf_SMPolicyControl_Create Response)下发至SMF，SMF保存PCC rule，其中包含终端装置签约的应用服务器的部署位置(应用服务器的部署位置可以用DNAI来表示)、域名和应用服务器的IP地址的对应关系。另外，PCC rule里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些部署位置的应用服务器(即DNAI列表)或者哪些应用服务器的IP地址(即IP地址列表)或者哪些应用服务器对应的域名(即域名列表)或者哪些目的地址(即DNS服务器的地址列表)可以执行ULCL/BP插入新的PSA等。
S406，SMF根据S-NSSAI和DNN等参数选择UPF1网元作为本PDU会话的锚点(PSA-1)，并且，如果SMF根据PCC rule里面包含的应用服务器的部署位置(应用服务器的部署位置可以用DNAI来表示)判断出终端装置签约了MEC平台部署的某些应用，那么SMF向该UPF1发送N4会话(N4 session)建立请求消息，N4 session建立请求消息中需要携带DNS查询消息的转发规则，用于指示UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至SMF。
S407，PDU会话建立完成之后，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(DNS query)，发起某个应用的DNS查询，DNS查询请求携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以FQDN或者是其他形式的域名，本申请不做限定。
S408，UPF1接收到DNS查询请求后，根据S406中SMF的指示将终端装置的DNS查询请求消息转发到SMF。
S409a，SMF检测DNS查询请求包括的域名，如果该域名包括在从S405获取的应用服务器的部署位置、域名和应用服务器的IP地址对应关系里面，则SMF确定终端装置当前可以访问的域名对应的应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)，在该应用服务器的部署位置基础上，进一步的根据DNS查询请求包括的域名确定对应的应用服务器的IP地址。
在S409a中，SMF确定终端装置当前可以访问的域名对应的应用服务器的部署位置的具体实现方式可以是：
SMF可以根据S402步骤中从AMF获取的终端装置的TAI，终端装置请求的域名以及S405步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系确定终端装置请求的域名对应的应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)，SMF获取终端装置的TAI的方法可以是在会话建立过程中，SMF从AMF获取终端装置的TAI，同时，SMF也可以向AMF订阅终端装置的TAI，这样当终端装置发生了移动，AMF可以向SMF提供终端装置当前所在的最新的TAI。SMF还可以根据终端装置的上下文信息确定服务于该终端装置的用户面功能网元的IP地址或者服务于该终端装置的用户面功能网元的ID，并进一步地确定终端装置请求的域名对应的应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)。
由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。
可选的，SMF可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据S405中从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否执行ULCL/BP插入流程。其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。上述方法中，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
可选的，在上述的S409a中，如果SMF确定终端装置请求的域名不包含在PCC rule里面，换句话说，如果SMF无法根据PCC rule确定域名对应的IP地址，则SMF不执行S409a，执行S409b和S409c:
S409b，SMF将终端装置的位置添加到DNS查询请求消息，并转发DNS查询请求消息到DNS服务器(server)获取该应用对应的应用服务器的IP地址。其中，终端装置的 位置可以是终端装置的TAI，或者是终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI。终端装置的位置还可以是当前服务终端装置的接入网标识。例如，接入网标识可以是RAN ID或者RAN IP地址。终端装置的位置信息的具体描述还可以参考步骤S231中的描述，为了简洁，这里不再赘述。其中，SMF将终端装置的位置信息添加到该DNS查询请求的具体实现方法可以是：SMF在DNS查询请求(DNS报文)选项中增添终端装置的位置信息。或者，由于TCP可以承载DNS报文，SMF还可以在TCP选项(option)中增添终端装置的位置信息，本申请不做限定。
可选的，作为一种实现方式，SMF还可以将DNS查询请求消息发送到DNS服务器(server)之后，再将终端装置的位置信息发送至DNS服务器(server)，换句话说，SMF可以将DNS查询请求消息和终端装置的位置信息分多条消息发送至DNS服务器，本申请不做限定。
S409c，DNS server通过DNS查询请求的域名确定对应的应用服务器的IP地址，并发送给SMF。
S410，SMF向PSA-1返回DNS查询响应(response)，其中包括应用服务器的IP地址。
S411，PSA-1向终端装置返回DNS查询响应(response)，其中包括应用服务器的IP地址。后续终端装置使用DNS查询响应中包含的应用服务器的IP地址，通过PSA-1与应用服务器之间进行通信。
S412，可选的，SMF可以根据该查询响应，执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据S405中从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
本申请实施例提供的域名查询的方法，通过根据终端装置的位置和请求的域名，确定出与终端装置的位置和域名均对应的应用服务器的IP地址，并将该应用服务器的IP地址反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。提高了终端装置访问业务的质量。通过在与终端位置对应的应用服务器的部署位置上插入PSA。可以优化终端装置的数据传输路径。降低数据传输时延，提高数据传输的效率。
图11是本申请一个实施例的域名系统查询的方法500的示意性流程图，该方法400可以应用在图1所示的架构中。图11所示的流程主要描述了在终端装置位置移动的情况下会话管理网元确定应用服务器的IP地址过程。图11所示的例子中，会话管理网元以SMF为例、策略控制功能网元以PCF为例、应用功能网元以AF为例进行说明。
如图11所示，该方法500包括：
S501，AF将应用服务器的部署位置(例如可以利用MEC平台的标识或者DNAI表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)通过NEF网元 存储到UDR里面。假设终端装置在位置-1发起PDU会话建立流程，在PDU会话建立过程中，SMF通过PCF获取到应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系。终端装置在会话建立完成之后发起DNS查询请求，DNS查询请求包括需要查询的域名。SMF根据终端装置当前的位置(位置-1)信息确定终端装置当前的位置对应的应用服务器的部署位置，进一步地，根据应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系确定终端装置查询的域名对应的应用服务器的IP地址。并将确定的应用服务器的IP地址通知给终端装置。可选的，如果由于终端装置当前所在的位置(位置-1)没有部署应用服务器，则SMF返回的域名对应的应用服务器的IP地址为距离终端装置的当前位置较远的远端应用服务器(例如表1中的部署在MEC平台-1的应用服务器)的IP地址(例如IP-3A)。S501的具体过程可以参考上述的S401至S411的描述，为了简洁，这里不再赘述。
S502，终端装置的位置发生了移动，假设终端装置的位置从位置-1移动到位置-2。SMF从AMF获取到终端装置当前所在的新的位置信息(位置-2)。并且，SMF可以判断出终端装置当前所在的位置对应的应用服务器的部署位置(例如可以用DNAI或者MEC平台的标识来表示)发生了改变。例如，SMF判断终端装置的所在的位置-1(例如可以用TAI-1表示)对应DNAI2或者MEC平台-2，位置-2(例如可以用TAI-2表示)对应DNAI1或者MEC平台-1，其中，DNAI1跟DNAI2不同，则SMF判断出终端装置当前所在的位置对应的应用服务器的部署位置发生了改变。
S503，由于不同的应用服务器的部署位置对应不同的应用服务器的IP地址，SMF可以触发终端装置更新DNS缓存，以便于终端装置在当前位置(位置-2)再次发起DNS查询时，获取到最新的应用服务器的IP地址。SMF可以通过控制面信令向终端装置发送DNS缓存更新指示信息。例如，如S503a所示的，SMF可以直接通过接入网设备向终端装置发送控制面信令，如N1接口会话管理(session management，SM)消息，该N1SM消息中包含协议配置选项(protocol configuration options，PCO)，其中在PCO中包含DNS缓存更新指示信息，用于指示终端装置发起DNS缓存更新。或者，如S503b所示的，SMF通过UPF1向终端装置发送一个用户面报文，该报文用于指示终端装置发起DNS缓存更新。
S504，终端装置收到DNS缓存更新指示信息之后，发起DNS查询过程。具体的，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名，可选的，该DNS查询请求还包括目的地址(DNS服务器的地址)。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S505，UPF1接收到DNS查询请求后，将终端装置的DNS查询请求消息转发到SMF。
S506，SMF检测终端装置请求的域名，并根据终端装置的当前位置(位置-2)确定应用服务器的部署位置，进一步的确定该部署位置上的应用服务器的IP地址。S506的具体过程可以参考上述的S409a和S409c中的描述，为了简洁，这里不再赘述。
可选的，SMF可以根据该DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2 (PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择UPF2(PSA-2)和UL CL/BP，其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择UPF2(PSA-2)和UL CL/BP。上述方法中，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S507，SMF向PSA-1返回DNS查询响应(response)，其中包括应用服务器的IP地址。
S508，PSA-1向终端装置返回DNS查询响应，其中包括应用服务器的IP地址。后续终端装置使用DNS查询响应中包含的应用服务器的IP地址，通过PSA-1与应用服务器之间进行通信。
S509，可选的，SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。S509的具体过程可以参考上述的S412的描述。为了简洁，这里不在赘述。
本申请实施例提供的域名查询的方法，在终端装置的位置移动场景下，通过核心网网元触发终端装置执行DNS缓存更新指示，不仅可以保证终端装置在新位置就近获取到应用服务器的IP地址，还可以根据终端装置的业务访问动态插入ULCL/BP，实现本地分流，优化本地业务访问的路径，提高通信效率。
图12是本申请一个实施例的域名系统查询的方法600的示意性流程图，该方法600可以应用在图1所示的架构中。图12所示的流程主要描述了SMF网元和UPF网元在拓扑增强(enhancing Topology of SMF and UPF，ETSUN)场景中确定域名对应的应用服务器的IP地址的过程。例如，在5G中，由于不同的SMF管理的服务区域不同，同一个PDU会话可能会对应两个SMF网元，分别为第一会话管理网元和第二会话管理网元。具体的，终端装置在位置-1建立PDU会话时，该PDU会话有对应的锚点用户面功能网元(例如UPF1)，该锚点用户面功能网元由锚点SMF管理。当终端由位置-1移动到位置-2时发生PDU会话切换，PDU会话切换后该PDU会话对应的与接入网网元直接连接的用户面功能网元超出了原锚点SMF服务区域，而是新的锚点中间SMF(intermediate SMF，I-SMF)进行管理。此时，会出现会话对应了两个SMF，即第一会话管理网元(SMF)和第二会话管理网元(I-SMF)的场景。当然，本申请实施例也不一定限于会话切换的场景，例如，还可适用于例如PDU会话对应两个(或者多个)SMF网元的场景。图12所示的例子中，表示的是在PDU会话建立过程中就插入I-SMF的具体过程。会话管理网元以SMF为例、策略控制功能网元以PCF为例、应用功能网元以AF为例进行说明。
如图12所示，该方法600包括：
S601，AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)存储到DNS服务器中。进一步的，还可以将第一信息存储到UDR中。例如，第一信息的内容可以为上述的表1所示的内容。S601的具体过程可以参考上述的S401的描述，为了简洁，这里不再赘述。
S602，终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、S-NSSAI和DNN等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF和I-SMF网元，并将SMF网元的标识、该终端装置的永久标识、终端装置的位置信息(例如TAI)、PDU会话标识，S-NSSAI和DNN等参数发送给I-SMF网元。
S603，I-SMF网元选择中间UPF(intermediate UPF，I-UPF)网元。
S604，I-SMF调用PDU会话创建请求(Nsmf_PDUSession_Create request)，该PDU会话创建请求携带I-SMF支持的DNAI列表，发送至SMF网元。
S605，SMF调用PCF的服务化操作策略建立控制请求(Npcf_SMPolicy Control_Create Request)，请求从PCF获取该PDU会话相关的策略信息。PCF调用UDR的服务化操作请求(Nudr_DM_Query)，从UDR获取该终端装置签约的应用相关的信息，其中包含S601中的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)。
S606，PCF将该应用服务器的部署位置、域名和应用服务器的IP地址生成策略计费控制规则(Policy and Charging Control rule，PCC rule)，通过服务化操作策略建立控制响应(Npcf_SMPolicyControl_Create Response)下发至SMF，SMF保存PCC rule，其中包含终端装置签约的应用服务器的部署位置、域名和应用服务器的IP地址的对应关系。另外，PCC rule里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些部署位置的应用服务器(即DNAI列表)或者哪些应用服务器的IP地址(即IP地址列表)或者哪些应用服务器对应的域名(即域名列表)或者哪些目的地址(即DNS服务器的地址列表)可以执行ULCL/BP插入新的PSA等。S607，SMF根据S-NSSAI和DNN等参数选择UPF1网元作为本PDU会话的锚点(PSA-1)。
S608，SMF根据I-SMF支持的DNAI列表，将该I-SMF支持的那些应用服务器的部署位置(例如利用MEC平台标识或者DNAI表示)所部署的应用信息发送给I-SMF。应用信息包含应用服务器的部署位置、域名和应用服务器的IP地址的对应关系。此外，SMF根据I-SMF支持的应用服务器的部署位置的应用信息，将可以执行ULCL/BP插入的应用服务器的部署位置(MEC平台)、应用服务器的IP地址(即IP地址列表)、应用服务器对应的域名(即域名列表)以及目的地址(即DNS服务器的地址列表)中的一个或者多个发给I-SMF。
S609，I-SMF接收到支持的应用服务器的部署位置上所部署的应用信息，并向I-UPF发送DNS查询请求的转发规则，用于指示I-UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至I-SMF。
S610，PDU会话建立完成之后，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，该DNS查询请求还可以包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域 名，本申请不做限定。
S611，I-UPF接收到DNS查询请求后，根据S609中I-SMF的指示将终端装置的DNS查询请求消息转发到I-SMF。
S612，I-SMF检测终端装置请求的域名，并根据终端装置的TAI确定请求的域名对应的应用服务器的部署位置，例如可以利用管理平台的标识或者DNAI表示，进一步的确定该部署位置上的与该域名对应的应用服务的IP地址。
应理解，由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。
可选的，I-SMF可以根据该DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，I-SMF网元上可以提前预先配置域名列表，或者I-SMF网元根据S608中从SMF网元接收的指示信息，该指示信息包含域名列表，该域名列表包含一个或者多个域名，只要I-SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么I-SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，I-SMF确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，I-SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。
可选的，I-SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择UPF2(PSA-2)和UL CL/BP，其中，该目的地址可以理解为是DNS服务器的地址。当I-SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么I-SMF就确定为该终端装置选择UPF2(PSA-2)和UL CL/BP。上述方法中，如果I-SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S613，I-SMF向I-UPF返回DNS查询响应(response)，其中包括确定的应用服务器的IP地址。
S614，I-UPF向终端装置返回DNS查询响应，其中包括应用服务器的IP地址。后续终端装置使用DNS查询响应中包含的应用服务器的IP地址，通过I-UPF与应用服务器之间进行通信。
S615，可选的，I-SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，I-SMF网元上可以提前预先配置IP地址列表，或者I-SMF网元根据S608中从SMF网元接收的指示信息，该指示信息包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要I-SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么I-SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当I-SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么I-SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
图13是本申请另一个实施例的域名系统查询的方法600的示意性流程图，与图12所示的例子不同的是，图13所示的例子中是在后续终端装置的位置发生变化后才插入I-SMF的具体过程。图12所示的为在PDU会话建立的过程中插入I-SMF。图13所示的例子中。 会话管理网元以SMF为例、策略控制功能网元以PCF为例、应用功能网元以AF为例进行说明。
如图13所示，该方法700包括：
S701，AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)通过NEF网元存储到UDR里面。假设终端装置在位置-1发起PDU会话建立流程，在PDU会话建立过程中，SMF通过PCF获取到应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系。终端装置在会话建立完成之后发起DNS查询请求，DNS查询请求包括需要查询的域名。SMF根据终端装置当前的位置(位置-1)信息确定终端装置当前的位置对应的DNAI。进一步地，根据应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系确定终端装置查询的域名对应的应用服务器的IP地址。并将确定的应用服务器的IP地址通知给终端装置。可选的，如果由于终端装置当前所在的位置(位置-1)没有部署应用服务器，则SMF返回的域名对应的应用服务器的IP地址为距离终端装置的当前位置较远的远端应用服务器(例如表1中的部署在MEC平台-1的应用服务器)的IP地址(例如IP-3A)。S701的具体过程可以参考上述的S401至S411的描述，为了简洁，这里不再赘述。
S702，终端装置的位置发生了移动，假设终端装置的位置从位置-1移动到位置-2。AMF判断出UE移出了SMF的服务范围，则AMF插入I-SMF。
S703，I-SMF调用PDU会话创建请求(Nsmf_PDUSession_Create request)，该PDU会话创建请求携带I-SMF支持的DNAI列表，发送至SMF网元。
S704，SMF根据I-SMF支持的DNAI列表，将该I-SMF支持的那些应用服务器的部署位置所部署的应用信息发送给I-SMF。应用信息包含应用服务器的部署位置、域名和应用服务器的IP地址的对应关系。此外，SMF根据I-SMF支持的应用服务器的部署位置上的应用信息，将可以执行ULCL/BP插入的应用服务器的部署位置(MEC平台)、应用服务器的IP地址(即IP地址列表)、应用服务器对应的域名(即域名列表)以及目的地址(即DNS服务器的地址列表)中的一个或者多个发给I-SMF。其中，应用的目的地址、部署位置、域名和IP地址的对应关系是SMF在会话建立过程中从PCF获取的。
S705，I-SMF接收I-SMF支持的应用服务器的部署位置上所部署的应用信息，并向I-UPF发送N4 session修改请求消息，其中需要携带DNS查询消息的转发规则，用于指示I-UPF收到UE的DNS查询消息后，将该DNS查询消息转发至I-SMF。
S706，由于插入I-SMF之前是SMF执行的DNS解析，插入I-SMF之后，I-SMF并不知道终端装置在插入之前查询过哪些应用的域名，因此I-SMF需要触发终端装置更新DNS缓存，以便于终端装置在当前位置(位置-2)再次发起DNS查询时，获取到最新的应用服务器的IP地址。I-SMF可以通过控制面信令向终端装置发送DNS缓存更新指示信息。例如，如S706a所示的，I-SMF可以直接通过接入网设备向终端装置发送N1SM消息，该N1SM消息中包含PCO，其中在PCO中包含DNS缓存更新指示信息，用于指示终端装置发起DNS缓存更新。或者如S706b所示的，I-SMF通过I-UPF向终端装置发送一个用户面报文，该报文用于指示终端装置发起DNS缓存更新。
S707，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求 (query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S708，I-UPF接收到DNS查询请求后，根据S705中I-SMF的指示将终端装置的DNS查询请求消息转发到I-SMF。
S709，I-SMF检测终端装置请求的域名，并根据终端装置的当前位置(如TAI)确定终端装置请求的域名对应的应用服务器的部署位置，进一步的确定该部署位置上的与该域名对应的应用服务的IP地址。S709的具体过程可以参考上述的S409a，或者S408b和S408c的描述。为了简洁，这里不在赘述。
可选的，I-SMF可以根据DNS查询请求包括的域名，执行ULCL/BP插入流程。具体过程可以参考S612的描述，为了简洁，这里不再赘述。
S710，I-SMF向I-UPF返回DNS查询响应(response)，其中包括应用服务器的IP地址。
S711，I-UPF向终端装置返回DNS查询响应，其中包括应用服务器的IP地址。后续终端装置使用DNS查询响应中包含的应用服务器的IP地址，通过I-UPF与应用服务器之间进行通信。
S712，可选的，I-SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，I-SMF网元上可以提前预先配置IP地址列表，或者I-SMF网元根据S704中从SMF网元接收的指示信息，该指示信息包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要I-SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么I-SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当I-SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么I-SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
本申请实施例提供的域名查询的方法，在ETSUN场景下，由I-SMF执行DNS查询请求的解析，可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化本地业务访问的路径，提高通信效率。
图14是本申请一个实施例的域名系统查询的方法800的示意性流程图，该方法800可以应用在图1所示的架构中。图14所示的流程主要描述了增强DNS服务器，使得DNS服务器存储上述的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系的信息，当SMF/UPF在解析DNS报文(DNS查询请求)后，将终端装置的位置主动添加到到DNS查询请求中，并将包括终端装置查询的域名和与终端装置位置的DNS查询请求发送给DNS服务器。DNS服务器根据DNS查询请求，返回与域名和终端装置的位置对应的IP地址。进一步地，SMF还可以根据在DNS response消息中的IP地址为终端设备插入ULCL/BP优化本地业务访问的路径。其中，会话管理网元以SMF为例、策略控制功能网元以PCF为例、用户面功能网元以UPF为例，应用功能网元以AF为例进行说明。
如图14所示，该方法800包括：
S801，DNS服务器存储应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)。其 中，DNS服务器获取应用服务器的部署位置的方法可以是：AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)存储到DNS服务器中。进一步的，AF还可以将第一信息通过NEF网元存储到UDR中。该过程的具体描述可以参考上述的S401的描述，为了简洁，这里不再赘述。
S802，终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、S-NSSAI和DNN等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF，并将SMF网元的标识、该终端装置的永久标识、终端装置的位置信息、PDU会话标识，S-NSSAI和DNN等参数发送给SMF网元。其中，终端装置的位置信息包括终端装置的TAI。
可选的，在PDU会话建立过程中，SMF通过PCF获取到应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系。
S803，SMF根据S802步骤中获取的终端装置的位置信息确定终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI。
如果是UPF主动添加终端装置的位置信息的方案，那么S803后续的流程为：
S8041，SMF选择UPF1之后，将S803步骤确定的终端装置的位置发给UPF1，其中，终端装置的位置可以是终端装置的TAI，或者是终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI。终端装置的位置还可以是当前服务终端装置的接入网标识。例如，接入网标识可以是RAN ID或者RAN IP地址。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。同时SMF向UPF1发送指示信息，用于指示UPF1收到UE的DNS查询请求后，在DNS查询请求消息中插入终端装置的位置信息。
S8042，终端装置根据自己的业务需求，通过接入网设备向核心网UPF1发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S8043，UPF1接收到DNS查询请求后，将S8041从SMF接收的该终端装置的位置信息添加到DNS请求中并发送给DNS服务器。其中，终端装置的位置可以包括终端装置的TAI，或者包括终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI，终端装置的位置可以包括当前服务于该终端装置的接入网标识。例如，接入网标识可以是RAN ID或者RAN IP地址。
可选的，UPF1还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向SMF发送通知信息，该通知信息用于SMF为终端装置选择分流节点(如UL CL/BP)和锚点UPF。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1上可以提前预先配置第一规则，或者在S8041步骤中UPF1从SMF接收第一规则，当域名或者目的地址满足第一规则时，UPF1向SMF发送通知信息。相应地，UPF1从SMF接收分流节点和锚点UPF2的标识信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要UPF1接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的目的地址满足向SMF发送第一通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条 件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要UPF1接收的DNS查询请求中包含的域名属于该域名列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的域名满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
进一步地，如果在S8041中，UPF1没有从SMF接收该终端装置的位置信息，那么UPF1接收到DNS查询请求后，UPF1可以通过如下两种方式中的任一种向DNS服务器发送DNS请求。
第一种：UPF1可以将UPF2的标识信息添加到DNS请求中并发送给DNS服务器。需要注意的是，这里的UPF2可以理解为与终端装置当前位置距离最近的MEC平台相连接的锚点UPF。UPF2的标识信息可以是UPF2ID或者UPF2IP地址。其中，UPF2的标识信息是UPF1从SMF获取的。在一种实现方式中，当UPF1恰好为与终端装置当前位置距离最近的MEC平台相连接的锚点UPF时，那么UPF1接收到DNS查询请求后，将UPF1自己的标识信息添加到DNS请求中并发送给DNS服务器。
第二种：UPF1可以向SMF网元发送通知消息，通知消息中包含终端装置请求的域名。SMF根据S802步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系、终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(即该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。进一步地，SMF将该终端装置的位置信息发送至UPF1，用于UPF1将该终端装置的位置信息插入到DNS请求中并发送给DNS服务器。其中，该终端装置的位置信息包括但不限于：该终端装置的TAI，用于标识该管理平台的DNAI、连接该管理平台的用户面功能网元的标识信息，或者指向该管理平台的IP地址。该管理平台即为上述描述中确定的部署了终端装置请求的域名对应的应用服务器的管理平台。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。
可选的，SMF根据S802步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。
S8044，DNS服务器根据DNS查询请求里包含的终端装置的位置信息以及域名确定对应的IP地址。具体的，如果DNS查询请求包含的终端装置的位置信息是MEC平台标识或者DNAI，那么DNS服务器根据S801存储的第一信息以及MEC平台标识或者DNAI，确定域名确定对应的IP地址。如果DNS查询请求里包含的终端装置的位置信息是当前服务终端装置的接入网标识或者UPF1的标识信息，那么DNS服务器首先根据接入网标识或者UPF1的标识信息确定终端装置当前能访问的MEC平台标识或者终端装置当前能访 问的DNAI，进一步地，DNS服务器根据S801存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S8045，DNS服务器并通过DNS响应(response)向UPF1返回该IP地址。
S8046，UPF1根据DNS response消息中的IP地址，确定是否向SMF发送通知信息，该通知信息用于通知SMF为该终端装置插入UL CL/BP，优化业务访问的路径。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当IP地址满足第一规则时，UPF1向会话管理网元发送第一通知信息。例如，第一规则包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要DNS响应(response)中的应用服务器的IP地址属于该IP地址列表，那么UPF1就根据该IP地址，向SMF发送通知信息。换句话说，如果UPF1判断出DNS response消息中的IP地址满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS响应(response)中的应用服务器的IP地址是第一规则中包含的任意一个IP地址。
如果是SMF主动添加终端装置的位置信息的方案，那么S803后续的流程为：
S8051，SMF选择UPF1之后，向UPF1发送DNS查询消息的转发规则，用于指示UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至SMF。
S8052，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，该DNS查询请求还可以包括目的地址，该目的地址为DNS服务器的地址。
S8053，UPF1接收到DNS查询请求后，将该DNS查询请求转发给SMF。
S8054，SMF接收到DNS查询请求后，根据S802步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。SMF将该终端装置的位置信息添加到DNS请求中并发送给DNS服务器。其中，该终端装置的位置信息包括但是不限于：该终端装置的TAI，用于标识该管理平台的DNAI、连接该管理平台的用户面功能网元的标识信息，或者指向该管理平台的IP地址。该管理平台即为上述描述中确定的部署了终端装置请求的域名对应的应用服务器的管理平台。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。
可选的，SMF还可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择第一分流节点和第一PSA，其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的 应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。通过上述方法，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S8055，DNS服务器根据DNS查询请求里包含的终端装置的位置信息以及域名，确定对应的IP地址。具体的，如果DNS查询请求里包含的终端装置的位置信息是MEC平台标识或者DNAI，那么DNS服务器根据S801存储的第一信息以及MEC平台标识或者DNAI，确定域名确定对应的IP地址。如果DNS查询请求里包含的终端装置的位置信息是当前服务UE的接入网标识或者UPF的标识信息，那么DNS服务器首先根据接入网标识或者UPF的标识信息确定终端装置当前能访问的MEC平台标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据S801存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。上述UPF的标识信息可以参考S8043或者S8044中描述的UPF2的标识信息的描述，为了简洁，这里不在赘述。
S8056，DNS服务器通过DNS响应消息向SMF返回该IP地址。
S8057，可选的，SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。SMF为该终端装置插入UL CL/BP，优化业务访问的路径。
应该理解的是，上述流程是SMF/UPF自己根据终端装置的位置信息(例如TAI或者用户面功能网元的IP地址或者该终端接入的无线接入网的IP地址)确定出对应的MEC平台的标识或者DNAI，并将该MEC平台的标识或者DNAI添加到DNS查询请求中。可选的，DNS服务器还可以自己根据终端装置的位置(例如TAI)确定出MEC平台或者DNAI，因此，SMF/UPF解析出DNS报文(DNS请求)之后，还可以将终端装置的位置信息(例如TAI)添加到DNS请求发送给DNS服务器。DNS服务器收到终端装置的位置信息之后，根据TAI确定出MEC平台标识或者DNAI，再进一步根据MEC平台标识或者DNAI，以及DNS请求中的域名判断出应用的IP地址。
由于终端装置具有移动性，如果终端装置发生了移动，那么当SMF/UPF在解析DNS查询请求后，需要根据终端装置的最新位置信息添加在DNS查询请求中，DNS服务器根据DNS查询请求里包含的终端装置的位置信息以及域名返回对应的IP地址。终端装置在移动场景下DNS查询的流程跟上图14类似，不同在于，如果是UPF主动添加终端装置的位置信息的方案，那么一旦SMF检测出终端装置移动导致了终端装置的位置改变(例如对应的MEC平台标识或者DNAI变化)，那么SMF要将新的终端装置的位置(例如新的MEC平台标识或者DNAI)发送至UPF，这样可以保证UPF收到终端装置的DNS查询请求之后，添加与终端装置的最新位置对应的最新MEC平台标识或者DNAI或者最新的终端装置的位置信息。如果是SMF主动添加终端装置的位置的方案，那么一旦SMF检测出终端装置的移动导致了MEC平台标识或者DNAI变化，那么SMF要将新的新的MEC 平台标识或者DNA或者最新的终端装置的位置信息添加到DNS查询请求发送至DNS服务器。
本申请实施例提供的域名查询的方法，通过增强DNS服务器，使得DNS服务器存储应用服务器的部署位置(例如MEC平台标识或者DNAI)、域名和应用服务器的IP地址之间的对应关系。当SMF/UPF在解析DNS查询请求后，根据终端装置的位置主动添加到DNS查询请求中并发给DNS服务器，DNS服务器根据DNS查询请求里包含的终端装置的位置和域名返回对应的IP地址；进一步地，SMF/UPF还可以根据DNS响应消息，触发SMF插入ULCL/BP优化本地业务访问的路径。可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化业务访问的路径，提高通信效率。
图15是本申请一个实施例的域名系统查询的方法900的示意性流程图，该方法600可以应用在图1所示的架构中。图15所示的流程主要描述了ETSUN场景由I-SMF/I-UPF根据终端装置的位置(例如TAI)主动添加其位置对应的应用服务器的部署位置(可以用MEC平台标识或者DNAI来表示)。如图15所示，该方法900包括：
S901，DNS服务器存储应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)。其中，DNS服务器获取应用服务器的部署位置的方法可以是：AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)存储到DNS服务器中。进一步的，AF还可以将第一信息通过NEF网元存储到UDR中。该过程的具体描述可以参考上述的S401的描述，为了简洁，这里不再赘述。
S902，终端装置在位置-1(例如TAI-1)发起了会话建立流程。
S903，终端设的位置发生了移动，从位置-1(TAI-1)移动到位置-2(TAI-2)，AMF判断出终端装置移出了SMF的服务范围，则AMF执行插入I-SMF。
可选的，在PDU会话建立过程中，I-SMF通过SMF从PCF获取到应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系。
S904，I-SMF根据终端装置的位置信息确定终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI。其中终端装置的位置信息是I-SMF从AMF获取的，获取的方法可以是插入I-SMF之后，I-SMF向AMF订阅终端装置的位置信息。这样当终端装置的位置发生了移动，AMF可以向I-SMF提供终端装置当前所在的最新的位置信息。
如果是UPF主动添加终端装置的位置信息的方案，那么S904后续的流程为：
S9051，I-SMF选择I-UPF，将S904步骤确定的终端装置的位置发给I-UPF，其中，终端装置的位置可以是终端装置的TAI，或者是与终端装置的TAI对应的MEC平台标识或者DNAI。终端装置的位置还可以是当前服务终端装置的接入网标识。例如，接入网标识可以是RAN ID或者RAN IP地址。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。同时I-SMF向I-UPF发送指示信息，用于指示I-UPF收到终端装置的DNS查询消息后，将终端装置的位置信息插入到DNS查询消息中。
S9052，由于插入I-SMF之前是SMF执行的DNS解析，插入I-SMF之后，I-SMF并不知道终端装置在插入之前查询过哪些应用的域名，因此I-SMF需要触发终端设更新DNS缓存，以便于终端装置在当前位置(位置-2)再次发起DNS查询时，获取到最新的应用 服务器的IP地址。例如，如S9052a所示的，I-SMF可以直接通过接入网设备向终端装置发送N1SM消息，该N1SM消息中包含PCO，其中在PCO中包含DNS缓存更新指示信息，用于指示终端装置发起DNS缓存更新。或者，如S9052b所示的，I-SMF通过I-UPF向终端装置发送一个用户面报文，该报文用于指示终端装置发起DNS缓存更新。
S9053，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。
S9054，I-UPF接收到DNS查询请求后，将S9051从I-SMF接收的该终端装置的位置信息添加到DNS请求中并发送给DNS服务器。可选的，I-UPF还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向I-SMF发送通知信息，该通知信息用于I-SMF为终端装置选择分流节点(如UL CL/BP)和锚点UPF，优化业务访问的路径。具体的，I-UPF确定向I-SMF发送通知信息的方法可以是：I-UPF上可以提前预先配置第一规则，或者I-UPF从I-SMF接收第一规则，当域名或者目的地址满足第一规则时，I-UPF向I-SMF发送通知信息。相应地，I-UPF从I-SMF接收分流节点和锚点UPF2的标识信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要I-UPF接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么I-UPF就确定向I-SMF发送通知信息。换句话说，如果I-UPF判断出DNS查询请求中包含的目的地址满足向I-SMF发送第一通知信息的条件，那么，I-UPF就向I-SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要I-UPF接收的DNS查询请求中包含的域名属于该域名列表，那么I-UPF就确定向I-SMF发送通知信息。换句话说，如果I-UPF判断出DNS查询请求中包含的域名满足向I-SMF发送通知信息的条件，那么，I-UPF就向I-SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
如果S9051中，I-UPF没有从I-SMF接收该终端装置的位置信息，那么I-UPF接收到DNS查询请求后，I-UPF可以通过如下两种方式中的任一种向DNS服务器发送DNS请求。
第一种，I-UPF将UPF2的标识信息添加到DNS请求中并发送给DNS服务器。需要注意的是，这里的UPF2可以理解为与终端装置当前位置距离最近的MEC平台相连接的UPF。UPF2的标识信息可以是UPF2ID或者UPF2IP地址。
第二种：I-UPF可以向I-SMF网元发送通知消息，通知消息中包含终端装置请求的域名。I-SMF根据S903步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。I-SMF将该终端装置的位置信息发送至I-UPF，用于I-UPF将该终端装置的位置信息插入到DNS query中并发送至DNS服务器。其中，该终端装置的位置信息包括但是不限于：该终端装置的TAI，用于标识该管理平台的DNAI、连接该管理平台的用户面功能网元的标识信息，或 者指向该管理平台的IP地址。该管理平台即为上述描述中确定的部署了终端装置请求的域名对应的应用服务器的管理平台。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。
可选的，I-SMF根据S903步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，I-SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。
S9055，DNS服务器根据DNS查询请求里包含的终端装置的位置信息和域名确定对应的IP地址。具体的，如果DNS查询请求里包含的终端装置的位置信息是MEC平台标识或者DNAI，那么DNS服务器根据S901存储的第一信息以及MEC平台标识或者DNAI，确定域名确定对应的IP地址。如果DNS查询请求里包含的终端装置的位置信息是当前服务终端装置的接入网标识或者UPF的标识信息，那么DNS服务器首先根据接入网标识或者UPF的标识信息确定终端装置当前能访问的MEC平台标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据S901存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S9056，DNS服务器通过DNS response向I-UPF返回该IP地址。
S9057，I-UPF根据DNS response消息中包含的IP地址(例如表1中的IP-1)，确定是否向I-SMF发送通知信息，该通知信息用于通知I-SMF为该终端装置插入UL CL/BP，优化本地业务访问的路径。具体的，I-UPF确定向I-SMF确定发送通知信息的方法可以是：I-UPF可以提前预先配置第一规则，或者I-UPF从I-SMF接收第一规则，当DNS response消息中包含的IP地址满足第一规则时，I-UPF确定向I-SMF发送通知信息。
例如，第一规则包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要DNS response消息中的IP地址属于该IP地址列表(例如表1中的IP-1)，那么I-UPF就根据该IP地址，向I-SMF发送通知信息。换句话说，如果I-UPF判断出DNS response消息中的IP地址满足向I-SMF发送通知信息的条件，那么，I-UPF就向I-SMF发送通知信息，其中，该条件可以是DNS响应(response)中的应用服务器的IP地址是第一规则中包含的任意一个IP地址。
如果是I-SMF主动添加终端装置的位置信息的方案，那么第S904后续的流程为：
S9061，I-SMF选择I-UPF，并向I-UPF发送DNS查询消息的转发规则，用于指示I-UPF收到终端装置的DNS查询请求后，将该DNS查询请求转发至I-SMF。
S9062，由于插入I-SMF之前是SMF执行的DNS解析，插入I-SMF之后，I-SMF并不知道终端装置在插入之前查询过哪些应用的域名，因此I-SMF需要触发终端设更新DNS缓存，以便于终端装置在当前位置(位置-2)再次发起DNS查询时，获取到最新的应用服务器的IP地址。例如，如S9062a所示的，I-SMF可以直接通过接入网设备向终端装置发送N1SM消息，该N1SM消息中包含PCO，其中在PCO中包含DNS缓存更新指示信息，用于指示终端装置发起DNS缓存更新。或者，如S9062b所示的，I-SMF通过I-UPF向终端装置发送一个用户面报文，该报文用于指示终端装置发起DNS缓存更新。
S9063，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求 (query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。
S9064，I-UPF接收到DNS查询请求后，将该DNS查询请求转发给I-SMF。
S9065，I-SMF接收到DNS查询请求后，根据S903步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。进一步地，I-SMF将与终端装置的位置信息添加到DNS请求中并发送给DNS服务器。其中，该终端装置的位置信息包括但不限于：该终端装置的TAI，用于标识该管理平台的DNAI、连接该管理平台的用户面功能网元的标识信息，或者指向该管理平台的IP地址。该管理平台即为上述描述中确定的部署了终端装置请求的域名对应的应用服务器的管理平台。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。
可选的，I-SMF可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，I-SMF网元上可以提前预先配置域名列表，或者I-SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要I-SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么I-SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择UPF2(PSA-2)和UL CL/BP，其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择UPF2(PSA-2)和UL CL/BP。通过上述方法如果I-SMF选择插入BP，I-SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S9066，DNS服务器根据DNS查询请求里包含的终端装置的位置和域名确定对应的IP地址。具体过程和S9055类似，具体描述可以参考上述对于S9055的描述，为了简洁，这里不再赘述。
S9067，DNS服务器通过DNS响应消息向I-SMF返回该IP地址。
S9068，可选的，I-SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，I-SMF网元上可以提前预先配置IP地址列表，或者I-SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要I-SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么I-SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当I-SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么I-SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。终端装置优化本地业务访问的路径。
应该理解的是，上述流程是I-SMF/I-UPF自己根据终端装置的位置信息(例如TAI或者服务于该终端装置的用户面功能网元的IP地址或者该终端接入的无线接入网的IP地 址)确定出对应的MEC平台的标识或者DNAI，并将该MEC平台的标识或者DNAI添加到DNS查询请求中。可选的，DNS服务器自己根据终端装置的位置(例如TAI)确定出MEC平台或者DNAI，因此，I-SMF/I-UPF解析出DNS报文(DNS请求)之后，还可以将终端装置的位置信息(例如TAI)添加到DNS请求发送给DNS服务器。DNS服务器收到终端装置的位置信息之后，根据TAI确定出MEC平台标识或者DNAI，再进一步根据MEC平台标识或者DNAI，以及DNS请求中的域名判断出应用的IP地址
本申请实施例提供的域名查询的方法，在ETSUN场景下，通过增强DNS服务器，使得DNS服务器存储应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系。当I-SMF/I-UPF在解析DNS查询请求后，将终端装置的位置主动添加到DNS查询请求中并发给DNS服务器。DNS服务器根据DNS查询请求里包含的终端装置的位置以及域名返回对应的IP地址。进一步地，I-SMF/I-UPF根据DNS响应消息触发I-SMF/插入ULCL/BP优化本地业务访问的路径。可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化业务访问的路径，提高通信效率。
图16是本申请一个实施例的域名系统查询的方法600的示意性流程图，该方法600可以应用在图1所示的架构中。图16所示的方法主要为UE的位置信息可以通过能力开放从应用功能网元(例如AF)从核心网获取，之后，由应用功能网元通知给DNS服务器。DNS服务器根据DNS查询请求中包括的域名以及上述的终端装置的位置信息确定对应的IP地址并返回该IP地址。如图16所示，该方法1000包括：
S1001，DNS服务器存储应用服务器的部署位置(例如可以用MEC平台标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)。其中，DNS服务器获取应用服务器的部署位置的方法可以是：AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和应用服务器的IP地址之间的对应关系(即上述的第一信息)存储到DNS服务器中。进一步的，AF还可以将第一信息通过NEF网元存储到UDR中。该过程的具体描述可以参考上述的S401的描述，为了简洁，这里不再赘述。
S1002，终端装置发起了PDU会话建立流程。
S1003，AF通过NEF向AMF或者SMF请求获取终端装置的位置信息，请求消息中携带终端装置的标识。
S1004，AMF或者SMF将终端装置的位置信息发送给AF。其中，终端装置的位置信息可以是终端装置的TAI，或者是与终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI，终端装置的位置还可以是当前服务终端装置的接入网标识。例如，接入网标识可以是RAN ID或者RAN IP地址。终端装置的位置信息的具体描述还可以参考步骤S231中的描述。
S1005，AF将终端装置的位置信息提供给DNS服务器。可选的，AF也可将终端装置的IP地址和应用标识发送给DNS服务器。DNS服务器存储这些信息。
S1006，AF向DNS服务器发送订阅请求，携带应用标识和订阅事件。其中，订阅事件可以是：当DNS服务器确定该终端装置请求的应用的域名满足条件时，则DNS服务器通知AF，例如，DNS服务器上可以提前预先配置域名列表或者通过其他方法获取域名列 表，该域名列表包含一个或者多个域名，只要DNS服务器网元接收的DNS查询请求中包含的域名是该域名列表中的任意一个域名，那么DNS服务器就会通知AF。换句话说，只要DNS服务器网元接收的DNS查询请求中包含的域名满足向AF发送订阅通知的条件，那么DNS服务器就会向AF发送订阅通知消息。
可选的，AF向DNS服务器发送的订阅事件还可以是：当DNS服务器确定该终端装置请求的应用的IP地址为满足条件时，则DNS服务器通知AF。例如，DNS服务器上可以提前预先配置IP地址列表或者通过其他方法获取IP地址列表，该IP列表包含一个或者多个IP地址，只要DNS服务器网元接收的DNS查询请求中包含的IP地址是该IP地址列表中的任意一个IP地址，那么DNS服务器就会通知AF。
S1007，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。
S1008，UPF接收到DNS查询请求后，将该DNS请求转发给DNS服务器。
可选的，UPF还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向SMF发送通知信息，该通知信息用于通知SMF选择分流节点和锚点PSA-2，优化业务访问的路径。具体的，UPF确定向SMF发送通知信息的方法可以是：UPF上可以提前预先配置第一规则，或者UPF从SMF接收第一规则，当域名或者目的地址满足第一规则时，UPF向SMF发送通知信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要UPF接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么UPF就确定向SMF发送通知信息。换句话说，如果UPF判断出DNS查询请求中包含的目的地址满足向SMF发送第一通知信息的条件，那么，UPF就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要UPF接收的DNS查询请求中包含的域名属于该域名列表，那么UPF就确定向SMF发送通知信息。换句话说，如果UPF判断出DNS查询请求中包含的域名满足向SMF发送通知信息的条件，那么，UPF就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
可选的，SMF可以获取DNS查询请求，并根据DNS查询请求包括的域名或者目的地址，确定是否执行ULCL/BP插入流程。具体过程可以参考S612的描述，为了简洁，这里不再赘述。
S1009，DNS服务器根据终端装置的位置信息和域名确定对应的IP地址。具体的，如果DNS查询请求里包含的终端装置的位置信息是MEC平台标识或者DNAI，那么DNS服务器根据S1001存储的第一信息以及MEC平台标识或者DNAI，确定域名确定对应的IP地址。如果DNS查询请求里包含的终端装置的位置信息是当前服务终端装置的接入网标识信息，那么DNS服务器首先根据接入网标识信息确定终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据S801存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S1010，可选的，DNS服务器根据S1006步骤中的订阅请求，如果DNS服务器确定该终 端装置请求的应用的域名或者IP地址满足向AF发送订阅通知的条件，那么DNS服务器向AF发送订阅通知信息，可选的，该订阅通知信息携带指示信息。指示信息用于指示AF：本次DNS查询获取到了满足条件的域名或者IP地址。同时，DNS暂时不向终端装置发送DNS响应消息，一直等待AF的回复。
S1011，AF通过NEF向SMF发送指示信息，用于指示SMF为该终端装置的PDU会话执行分流。
S1012，SMF选择PSA和UL CL/BP，并执行ULCL/BP插入流程，优化业务访问的路径。
S1013，SMF向AF发送通知信息，用于通知AF该终端装置的PDU会话分流成功。
S1014，AF向DNS服务器发送通知消息，通知DNS向终端装置返回该应用的IP地址。
S1015，DNS服务器在DNS响应消息中，应用的IP地址返回给终端装置。
本申请实施例提供的域名查询的方法，DNS服务器可以自行获取终端装置的位置信息，结合终端装置的DNS查询请求里包含域名信息，确定与终端装置的位和域名对应的应用服务器的IP地址，并将该应用服务器的IP地址反馈给终端装置。提高了DNS服务器确定该应用服务器的IP地址的效率。
图17是本申请一个实施例的域名系统查询的方法1100的示意性流程图，该方法1100可以应用在图1所示的架构中。图17所示的流程主要描述了在连接MEC平台的N6接口采用了NAT转换的场景下，增强DNS服务器，使得DNS服务器存储上述的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系的信息，同时，DNS服务器上也存储MEC平台入口处的公网IP地址空间(公网IP地址范围)与应用服务器的部署位置(用DNAI表示)之间的对应关系。公网IP地址空间包括多个公网IP。在会话建立过程中，SMF根据根据终端装置当前的TAI信息，确定终端装置请求的域名对应的应用服务器所在的MEC平台(用DNAI表示)，然后根据DNAI确定对应公网IP地址空间。其中，该公网IP地址空间包含至少一个IP地址，且该公网IP地址空间包含的任一公网IP地址均可以指向该MEC平台。当SMF/UPF在解析DNS报文(DNS查询请求)后，将指向管理平台的公网IP地址空间中包括的任一公网IP地址主动添加到到DNS查询请求中，并将包括终端装置查询的域名和公网IP地址的DNS查询请求发送给DNS服务器。其中，该管理平台是终端装置查询的域名对应的应用服务器所在的管理平台。DNS服务器根据DNS查询请求中包含的公网IP地址确定MEC平台的位置，进一步在该MEC平台上确定终端装置查询的域名对应的应用服务器的IP地址，DNS服务器返回与域名和公网IP地址所指示终端装置的位置对应的应用服务器的IP地址。进一步地，SMF还可以根据在DNS response消息中的IP地址为终端设备插入ULCL/BP优化本地业务访问的路径。其中，会话管理网元以SMF为例、策略控制功能网元以PCF为例、用户面功能网元以UPF为例，应用功能网元以AF为例进行说明。
如图17所示，该方法1100包括：
S1101，SMF获取MEC平台入口处的公网IP地址空间。其中，该公网IP地址空间包含至少一个IP地址，且该公网IP地址空间包含的任一公网IP地址均可以连接到该MEC平台。DNS服务器存储应用的部署位置(例如可以用MEC平台的标识或者DNAI来表示)、域名和IP地址的对应关系。DNS服务器上也存储了MEC平台入口处的公网IP地址与应 用服务器的部署位置(用DNAI表示)之间的对应关系。
可选的，SMF获取MEC平台入口处的公网IP地址空间的方法有两种：
方法一：SMF上配置连接每一个MEC平台入口处的公网IP地址空间，MEC平台的位置可以用DNAI来标识。即SMF存储DNAI与公网IP地址空间的对应关系。例如，公网IP地址空间可以用128.128.0.0至128.128.255.255来表示。
方法二：AF将应用对应的部署位置(应用对应的部署位置用DNAI表示)，该DNAI对应的MEC平台入口处的公网IP地址空间(公网IP地址范围)通过NEF发给UDR网元。即，UDR存储DNAI与公网IP地址空间的对应关系。例如，公网IP地址空间可以用128.128.0.0至128.128.255.255来表示。SMF可以在会话建立过程中通过PCF从UDR上获取该获取MEC平台入口处的公网IP地址空间。
S1102，终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、S-NSSAI和DNN等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF，并将SMF网元的标识、该终端装置的永久标识、终端装置的位置信息、PDU会话标识，S-NSSAI和DNN等参数发送给SMF网元。其中，终端装置的位置信息包括终端装置的TAI。
S1103，SMF根据S1102步骤中获取的终端装置的位置信息(即TAI)确定终端装置当前能访问的MEC平台的标识或者终端装置当前能访问的DNAI。同时。SMF根据终端装置当前位置确定MEC平台的位置DNAI，并进一步确定该DNAI对应的MEC平台入口处的公网IP地址空间。
如果是UPF主动添加公网IP地址的方案，那么S1103后续的流程为：
S1104，SMF为该PDU会话选择UPF1，并向UPF1发送指示信息以及公网IP地址，指示信息用于指示UPF1：收到终端装置的DNS查询请求之后，在DNS查询请求里面添加该公网IP地址，该公网IP地址指向
是终端装置当前位置对应的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。例如公网IP地址空间为128.128.0.0至128.128.255.255，那么，SMF可以将属于该公网IP地址空间的128.128.1.1作为MEC平台入口处的公网IP地址。其中，UPF1是与DNS服务器连接的UPF，即UPF1可以访问DNS服务器。
S1105，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1106，终端装置根据自己的业务需求，通过接入网设备向核心网UPF1发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S1107，UPF1接收到DNS查询请求后，将S1104从SMF接收的该公网IP地址添加到DNS请求中并发送给DNS服务器。
可选的，UPF1还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向SMF发送通知信息，该通知信息用于SMF为终端装置选择分流节点(如UL CL/BP)和锚点UPF。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1上可以提前预先配置第一规则，或者在S8041步骤中UPF1从SMF接收第一规则，当域名或者目的地址满足第一规则时，UPF1向SMF发送通知信息。相应地，UPF1从SMF接收分流节点和锚点UPF2的标识信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要UPF1接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的目的地址满足向SMF发送第一通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要UPF1接收的DNS查询请求中包含的域名属于该域名列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的域名满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
如果S1104中，UPF1没有从SMF接收IP地址，那么UPF1接收到DNS查询请求后，UPF1可以通过如下方式中向DNS服务器发送DNS请求。
例如，该方式为：UPF1可以向SMF网元发送通知消息，通知消息中包含终端装置请求的域名。SMF根据S1101步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系、终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(即该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应。进一步地，SMF将指向该管理平台的IP地址发送至UPF1，用于UPF1将该IP地址插入到DNS query中并发送至DNS服务器。该IP地址指向终端装置请求的域名对应的应用服务器所在的MEC平台。示例性地，该IP地址可以是公网IP地址，该公网IP地址是终端装置请求的域名对应的应用服务器所在的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。
可选的，SMF根据S802步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。
S1108，DNS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。具体的，DNS查询请求包含公网IP地址，DNS服务器根据S1101存储的MEC平台标识或者DNAI与公网IP地址之间的对应关系，确定终端装置当前能访问的MEC平台标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S1109，DNS服务器并通过DNS响应(response)向UPF1返回该IP地址。
S1110，可选的，UPF1根据DNS response消息中的IP地址，确定是否向SMF发送通知信息，该通知信息用于通知SMF为该终端装置插入UL CL/BP，优化业务访问的路径。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当IP地址满足第一规则时，UPF1向会话管理网元发送第一通知信息。例如，第一规则包含IP地址列表，该IP地址列表包含一个或者多 个IP地址，只要DNS响应(response)中的应用服务器的IP地址属于该IP地址列表，那么UPF1就根据该IP地址，向SMF发送通知信息。换句话说，如果UPF1判断出DNS response消息中的IP地址满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS响应(response)中的应用服务器的IP地址是第一规则中包含的任意一个IP地址。
如果是SMF主动添加主动添加公网IP地址的方案的方案，那么S1103后续的流程为：
S1111，SMF为该PDU会话选择UPF1，并向UPF1发送DNS查询消息的转发规则，用于指示UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至SMF。
S1112，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1113，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，该DNS查询请求还可以包括目的地址，该目的地址为DNS服务器的地址。
S1114，UPF1接收到DNS查询请求后，将该DNS查询请求转发给SMF。S1115，SMF接收到DNS查询请求后，根据应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系、终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(即该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。
进一步地，SMF将指向该管理平台的公网IP地址添加到DNS请求中并发送给DNS服务器。该公网IP地址是终端装置请求的域名对应的应用服务器所在的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。例如公网IP地址空间为128.128.0.0至128.128.255.255，那么，SMF可以将属于该公网IP地址空间的128.128.1.1作为MEC平台入口处的公网IP地址。
可选的，SMF还可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择第一分流节点和第一PSA，其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。通过上述方法，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S1116，NS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。该步骤可以参考S1108中的描述，为了简洁，这里不在赘述。
S1117，DNS服务器通过DNS响应消息向SMF返回该IP地址。
S1118，可选的，SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体 的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。SMF为该终端装置插入UL CL/BP，优化业务访问的路径。
由于终端装置具有移动性，如果终端装置发生了移动，那么当SMF/UPF在解析DNS查询请求后，需要根据终端装置的最新位置将连接终端装置当前位置对应的MEC平台的公网IP地址添加在DNS查询请求中，DNS服务器根据DNS查询请求里包含的公网IP地址确定终端装置当前位置对应的MEC平台，并根据终端装置请求的域名确定该MEC平台上的应用服务器对应的IP地址。终端装置在移动场景下DNS查询的流程跟上图17类似，不同在于，如果是UPF主动添加终端装置的位置信息的方案，那么一旦SMF检测出终端装置移动导致了终端装置的位置改变(例如对应的MEC平台标识或者DNAI变化)，那么SMF要将连接新的终端装置的位置对应的MEC平台(例如新的MEC平台标识或者DNAI)的公网IP地址发送给UPF，这样可以保证UPF收到终端装置的DNS查询请求之后，添加与终端装置的最新位置对应的公网IP地址。如果是SMF主动添加终端装置的位置的方案，那么一旦SMF检测出终端装置的移动导致了MEC平台标识或者DNAI变化，进一步的引起公网IP地址的变化，那么SMF要将新的新的公网IP地址添加到DNS查询请求发送至DNS服务器。
本申请实施例提供的域名查询的方法，如果连接MEC平台的N6接口采用了NAT转换，通过增强DNS服务器，使得DNS服务器存储应用服务器的部署位置(例如MEC平台标识或者DNAI)、域名和应用服务器的IP地址之间的对应关系、并且存储终端装置的MEC平台入口处的公网IP地址与应用服务器的部署位置之间的对应关系。当SMF/UPF在解析DNS查询请求后，将指向管理平台的公网IP地址主动添加到DNS查询请求中并发给DNS服务器，其中，该管理平台是终端装置请求的域名对应的应用服务器所在的管理平台。DNS服务器根据DNS查询请求里包含的公网IP地址和域名返回对应的应用服务器的IP地址；进一步地，SMF/UPF还可以根据DNS响应消息，触发SMF插入ULCL/BP优化本地业务访问的路径。可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化业务访问的路径，提高通信效率。
图18是本申请一个实施例的域名系统查询的方法1200的示意性流程图，该方法1200可以应用在图1所示的架构中。由于NAT简单遍历应用协议(simple traversal utilities for NAT，STUN)允许让位于内网的客户端发现网络中的地址转换器，进而找到NAT为自己配置的外网IP和端口。因此，SMF可以向与MEC平台连接的UPF发送请求消息，用于请求该UPF利用STUN协议获取NAT后的公网IP地址和端口号。图18所示的流程为UPF利用STUN协议获取NAT后的公网IP地址和该公网IP地址对应的端口号后，将该公网IP地址，或者将该公网IP地址和该端口号发给SMF的流程。同时，DNS服务器上也存储了MEC平台入口处的公网IP地址与应用服务器的部署位置(用DNAI表示)之 间的对应关系。当SMF/UPF在解析DNS报文(DNS查询请求)后，将指向管理平台的公网IP地址主动添加到到DNS查询请求中，该管理平台是终端装置请求的域名对应的应用服务器所在的管理平台。SMF/UPF将包括终端装置查询的域名和与公网IP地址的DNS查询请求发送给DNS服务器。DNS服务器根据DNS查询请求，返回与域名和公网IP地址的位置对应的应用服务器的IP地址。
如图18所示，该方法1200包括：
S1201，AF将应用服务器的部署位置(例如可以用MEC平台的标识或者DNAI来表示)以及该应用服务器支持的域名通过NEF网元存储到UDR中。
终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、S-NSSAI和DNN等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF，并将SMF网元的标识、该终端装置的永久标识、终端装置的位置信息、PDU会话标识，S-NSSAI和DNN等参数发送给SMF网元。其中，终端装置的位置信息包括终端装置的TAI。
S1202，SMF为该PDU会话选择UPF1，该UPF1与DNS服务器可以连接，即该UPF1可以访问DNS服务器。
S1203，SMF根据终端装置的当前位置确定该当前位置对应一个MEC平台，并进一步确定该MEC平台连接的UPF2。可选的，如果与MEC平台连接的UPF存在多个，这里，SMF可以从多个UPF中任意选择一个作为UPF2。
S1204，SMF向与MEC平台连接的UPF2发送请求消息，请求消息中包含指示信息，该指示信息用于请求该UPF2获取NAT后的公网IP地址和端口号。
S1205，UPF2收到指示信息之后，利用STUN协议探测NAT后的公网IP地址和端口号。
S1206，UPF2将公网IP地址发送至SMF网元。其中，这个公网IP地址也可以称为MEC平台入口处的公网IP地址。可选的，UPF2还以将公网IP地址对应的端口号发给SMF。
如果是UPF主动添加公网IP地址的方案，那么S1206后续的流程为：
S1207，SMF向UPF1发送指示信息，指示信息包括该公网IP地址，指示信息用于指示UPF1：收到终端装置的DNS查询请求消息之后，在DNS查询请求里面添加公网IP地址，这个公网IP地址是SMF在S1206中获取的MEC平台入口处的公网IP地址。可选的，如果SMF在S1206中收到了公网IP地址对应的端口号，那么SMF还可以将公网IP地址对应的端口号发给UPF1，用于UPF1将公网IP地址对应的端口号也添加在DNS查询请求消息中。
S1208，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1209，终端装置根据自己的业务需求，通过接入网设备向核心网UPF1发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S1210，UPF1接收到DNS查询请求后，将S1207从SMF接收的该公网IP地址添加到DNS请求中并发送给DNS服务器。可选的，如果UPF1在S1207中收到了公网IP地址对应的端口号，UPF1还可以将该端口号也添加在DNS查询请求里。
可选的，UPF1还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向 SMF发送通知信息，该通知信息用于SMF为终端装置选择分流节点(如UL CL/BP)和锚点UPF。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1上可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当域名或者目的地址满足第一规则时，UPF1向SMF发送通知信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要UPF1接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的目的地址满足向SMF发送第一通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要UPF1接收的DNS查询请求中包含的域名属于该域名列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的域名满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
如果S1207中，UPF1没有从SMF接收IP地址，那么UPF1接收到DNS查询请求后，UPF1可以通过如下方式向DNS服务器发送DNS请求。
例如，该方式为：UPF1可以向SMF网元发送通知消息，通知消息中包含终端装置请求的域名。SMF根据S1204步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系、终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(即该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应。进一步地，SMF将指向该管理平台的IP地址发送至UPF1，用于UPF1将该IP地址插入到DNS query中并发送至DNS服务器。该IP地址指向终端装置请求的域名对应的应用服务器所在的MEC平台。示例性地，该IP地址可以是公网IP地址，该公网IP地址是终端装置请求的域名对应的应用服务器所在的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。
可选的，SMF根据S802步骤中获取的应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系，终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置之后，SMF还可以根据应用服务器的部署位置(用DNAI来标识)来选择UL CL/BP，实现将该应用的业务流的本地分流，减少时延。
S1211，DNS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。具体的，DNS查询请求包含公网IP地址，DNS服务器根据存储的MEC平台标识或者DNAI与公网IP地址之间的对应关系，确定终端装置当前能访问的MEC平台标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S1212，DNS服务器并通过DNS响应(response)向UPF1返回该IP地址。
S1213，UPF1根据DNS response消息中的IP地址，确定是否向SMF发送通知信息， 该通知信息用于通知SMF为该终端装置插入UL CL/BP，优化业务访问的路径。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当IP地址满足第一规则时，UPF1向会话管理网元发送第一通知信息。例如，第一规则包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要DNS响应(response)中的应用服务器的IP地址属于该IP地址列表，那么UPF1就根据该IP地址，向SMF发送通知信息。换句话说，如果UPF1判断出DNS response消息中的IP地址满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS响应(response)中的应用服务器的IP地址是第一规则中包含的任意一个IP地址。
如果是SMF主动添加公网IP地址的方案，那么S1206后续的流程为：
S1214，SMF为该PDU会话选择UPF1，并向UPF1发送DNS查询消息的转发规则，用于指示UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至SMF。
S1215，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1216，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，该DNS查询请求还可以包括目的地址，该目的地址为DNS服务器的地址。
S1217，UPF1接收到DNS查询请求后，将该DNS查询请求转发给SMF。
S1218，SMF接收到DNS查询请求后，根据应用服务器的部署位置、域名和应用服务器的IP地址之间的对应关系、终端装置请求的域名以及终端装置的TAI，确定终端装置请求的域名对应的应用服务器所在的管理平台的位置，该应用服务器可以服务终端装置请求的域名，该应用服务器的部署位置(即该管理平台的位置)可以用DNAI来标识。由于该管理平台的位置是根据终端装置的TAI以及终端装置请求的域名确定的，该管理平台的位置与终端装置的位置对应，且该管理平台部署了终端装置请求的域名对应的应用服务器。
进一步地，SMF将指向该管理平台的公网IP地址添加到DNS请求中并发送给DNS服务器。公网IP地址是在S1206中获取的，该公网IP地址是终端装置当前位置对应的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。可选的，SMF还可以在DNS查询请求里面添加公网IP地址对应的端口号。
可选的，SMF还可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择第一分流节点和第一PSA，其中，该目的地址可以理解为是DNS服务器的地址。当SMF判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。通过上述方法，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S1219，DNS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。该步骤可以参考S1108中的描述，为了简洁，这里不在赘述。
S1220，DNS服务器通过DNS响应消息向SMF返回该IP地址。
S1221，可选的，SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF(PSA)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF和UL CL/BP，并执行ULCL/BP插入流程。SMF为该终端装置插入UL CL/BP，优化业务访问的路径。
本申请实施例提供的域名查询的方法，在连接MEC平台的N6接口采用了NAT转换的场景中，通过增强DNS服务器，使得DNS服务器存储应用服务器的部署位置(例如MEC平台标识或者DNAI)、域名和应用服务器的IP地址之间的对应关系、并且存储终端装置的MEC平台入口处的公网IP地址与应用服务器的部署位置之间的对应关系。当SMF/UPF在解析DNS查询请求后，获取指向管理平台的公网IP地址，该管理平台是终端装置请求的域名对应的应用服务器所在的管理平台。SMF/UPF将该公网IP地址主动添加到DNS查询请求中并发给DNS服务器，DNS服务器根据DNS查询请求里包含的公网IP地址和域名返回对应的应用服务器的IP地址；进一步地，SMF/UPF还可以根据DNS响应消息，触发SMF插入ULCL/BP优化本地业务访问的路径。可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化业务访问的路径，提高通信效率。
图19是本申请一个实施例的域名系统查询的方法1300的示意性流程图，该方法1300可以应用在图1所示的架构中。由于STUN允许让位于内网的客户端发现网络中的地址转换器，进而找到NAT为自己配置的外网IP和端口。因此，SMF也可以直接向STUN服务器请求获取NAT后的公网IP地址和端口号。同时，DNS服务器上也存储了MEC平台入口处的公网IP地址与应用服务器的部署位置(用DNAI表示)之间的对应关系。当SMF/UPF在解析DNS报文(DNS查询请求)后，将指向管理平台的公网IP地址主动添加到到DNS查询请求中，该管理平台是终端装置请求的域名对应的应用服务器所在的管理平台。SMF/UPF将包括终端装置查询的域名和与公网IP地址的DNS查询请求发送给DNS服务器。该公网IP地址可以是终端装置请求的域名对应的应用服务器所在的管理平台入口处的公网IP地址空间包括的任一公网IP地址。DNS服务器根据DNS查询请求，返回与域名和公网IP地址的位置对应的应用服务器的IP地址。
如图19所示，该方法1300包括：
S1301，终端装置发起了PDU会话建立流程。具体的，终端装置携带PDU会话标识、S-NSSAI和DNN等参数发给AMF。AMF根据S-NSSAI和DNN选择SMF，并将SMF网元的标识、该终端装置的永久标识、终端装置的位置信息、PDU会话标识，S-NSSAI和DNN等参数发送给SMF网元。其中，终端装置的位置信息包括终端装置的TAI。
S1302，SMF为该PDU会话选择UPF1。该UPF1与DNS服务器可以连接，即该UPF1可以访问DNS服务器。
S1303，SMF根据终端装置的当前位置确定该当前位置对应一个MEC平台，并进一步确定该MEC平台连接的UPF2。可选的，如果与MEC平台连接的UPF存在多个，这里，SMF可以从多个UPF中任意选择一个作为UPF2。
S1304，SMF向STUN服务器发送请求消息，携带与MEC平台连接的UPF2的IP地址，其中，该UPF2的IP地址是3GPP内部网络内的私网IP地址，STUN服务器根据该UPF2的IP地址确定NAT后的公网IP地址。具体过程可以为，STUN服务器上面可以配置3GPP内部网络的私网IP地址与公有IP地址一对一的关系。其中，这个公网IP地址也可以称为MEC平台入口处的公网IP地址。可选的，STUN服务器还以将公网IP地址对应的端口号发给SMF。
S1305，STUN服务器将公网IP地址发送给SMF。可选的，还可以将公网IP地址对应的端口号发给SMF。
如果是UPF主动添加公网IP地址的方案，那么S1305后续的流程为：
S1306，SMF向UPF1发送指示信息以及该公网IP地址，指示信息包括公网IP地址，指示信息用于指示UPF1：收到终端装置的DNS查询请求消息之后，在DNS查询请求里面添加公网IP地址，这个公网IP地址是SMF在S1305中获取的MEC平台入口处的公网IP地址。可选的，如果SMF在S1206中收到了公网IP地址对应的端口号，那么SMF还可以将公网IP地址对应的端口号发给UPF1，用于UPF1将公网IP地址对应的端口号也添加在DNS查询请求消息中。
S1307，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1308，终端装置根据自己的业务需求，通过接入网设备向核心网UPF1发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，DNS查询请求包括目的地址，该目的地址为DNS服务器的地址。其中，DNS查询请求携带的应用对应的域名可以是FQDN或者是其他形式的域名，本申请不做限定。
S1309，UPF1接收到DNS查询请求后，将S1306从SMF接收的该公网IP地址添加到DNS请求中并发送给DNS服务器。可选的，如果UPF1在S1306中收到了公网IP地址对应的端口号，UPF1还可以将该端口号也添加在DNS查询请求里。
可选的，UPF1还可以根据DNS查询请求消息中的域名或者目的地址，确定是否向SMF发送通知信息，该通知信息用于SMF为终端装置选择分流节点(如UL CL/BP)和锚点UPF。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1上可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当域名或者目的地址满足第一规则时，UPF1向SMF发送通知信息。
例如，第一规则包括目的地址列表，该目的地址列表包含一个或者多个目的地址，只要UPF1接收的DNS查询请求中包含的目的地址属于该目的地址列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的目的地址满足向SMF发送第一通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的目的地址是第一规则中包含的任意一个目的地址。
再例如，第一规则包括域名列表，该域名列表包含一个或者多个域名，只要UPF1接 收的DNS查询请求中包含的域名属于该域名列表，那么UPF1就确定向SMF发送通知信息。换句话说，如果UPF1判断出DNS查询请求中包含的域名满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS查询请求中包含的域名是第一规则中包含的任意一个域名。
S1310，DNS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。具体的，DNS查询请求包含公网IP地址，DNS服务器根据存储的MEC平台标识或者DNAI与公网IP地址之间的对应关系，确定终端装置当前能访问的MEC平台标识或者终端装置当前能访问的DNAI，进一步地，DNS服务器根据存储的第一信息以及该MEC平台标识或者DNAI，确定域名确定对应的IP地址。
S1311，DNS服务器并通过DNS响应(response)向UPF1返回该IP地址。
S1312，UPF1根据DNS response消息中的IP地址，确定是否向SMF发送通知信息，该通知信息用于通知SMF为该终端装置插入UL CL/BP，优化业务访问的路径。具体的，UPF1确定向SMF发送通知信息的方法可以是：UPF1可以提前预先配置第一规则，或者UPF1从SMF接收第一规则，当IP地址满足第一规则时，UPF1向会话管理网元发送第一通知信息。例如，第一规则包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要DNS响应(response)中的应用服务器的IP地址属于该IP地址列表，那么UPF1就根据该IP地址，向SMF发送通知信息。换句话说，如果UPF1判断出DNS response消息中的IP地址满足向SMF发送通知信息的条件，那么，UPF1就向SMF发送通知信息，其中，该条件可以是DNS响应(response)中的应用服务器的IP地址是第一规则中包含的任意一个IP地址。
如果是SMF主动添加公网IP地址的方案，那么S1305后续的流程为：
S1313，SMF选择UPF1之后，向UPF1发送DNS查询消息的转发规则，用于指示UPF收到终端装置的DNS查询消息后，将该DNS查询消息转发至SMF。
S1314，SMF向终端装置发送会话接受消息，携带DNS服务器地址信息。
S1315，终端装置根据自己的业务需求，通过接入网设备向核心网发送DNS查询请求(query)，发起某个应用的DNS查询，DNS query携带该应用对应的域名。可选的，该DNS查询请求还可以包括目的地址，该目的地址为DNS服务器的地址。
S1316，UPF1接收到DNS查询请求后，将该DNS查询请求转发给SMF。
S1317，SMF接收到DNS查询请求后，将该公网IP地址添加到DNS请求中并发送给DNS服务器。公网IP地址是在S1305中获取的，该公网IP地址是终端装置当前位置对应的MEC平台入口处的公网IP地址空间里面的任一公网IP地址。可选的，SMF还可以在DNS查询请求里面添加公网IP地址对应的端口号。
可选的，SMF还可以根据DNS查询请求包括的域名，确定是否执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置域名列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含域名列表，该域名列表包含一个或者多个域名，只要SMF网元接收的DNS查询请求中包含的域名属于该域名列表，那么SMF网元选择UPF2(PSA-2)和UL CL/BP，并执行ULCL/BP插入流程。
可选的，SMF还可以根据DNS查询请求包括的目的地址，确定是否为该终端装置选择第一分流节点和第一PSA，其中，该目的地址可以理解为是DNS服务器的地址。当SMF 判断该DNS服务器的地址指向第三方(如腾讯，阿里)，且当前位置部署了该第三方的应用服务器，那么SMF就确定为该终端装置选择第一分流节点和第一PSA。通过上述方法，如果SMF选择插入BP，SMF还需要为终端装置分配一个新的IPv6前缀，并通过PSA-1发送给终端装置。后续终端装置可以通过PSA-2访问该应用服务器。
S1318，DNS服务器根据DNS查询请求里包含的公网IP地址以及域名，确定对应的IP地址。该步骤可以参考S1108中的描述，为了简洁，这里不在赘述。
S1319，DNS服务器通过DNS响应消息向SMF返回该IP地址。
S1320，可选的，SMF可以根据该DNS查询响应，执行ULCL/BP插入流程。具体的，SMF网元上可以提前预先配置IP地址列表，或者SMF网元根据从PCF网元接收的PCC rule，该PCC rule包含IP地址列表，该IP地址列表包含一个或者多个IP地址，只要SMF网元接收的DNS查询响应中包含的IP地址属于该IP地址列表，那么SMF网元选择UPF(PSA)和UL CL/BP，并执行ULCL/BP插入流程。或者，当SMF网元确定该IP地址(例如表1中的IP-1)对应的应用服务器所在部署位置(例如表1中MEC平台-2)允许执行ULCL/BP插入，那么SMF选择UPF和UL CL/BP，并执行ULCL/BP插入流程。SMF为该终端装置插入UL CL/BP，优化业务访问的路径。
本申请实施例提供的域名查询的方法，在连接MEC平台的N6接口采用了NAT转换的场景中，通过增强DNS服务器，使得DNS服务器存储应用服务器的部署位置(例如MEC平台标识或者DNAI)、域名和应用服务器的IP地址之间的对应关系、并且存储终端装置的MEC平台入口处的公网IP地址与应用服务器的部署位置之间的对应关系。当SMF/UPF在解析DNS查询请求后，获取终端装置的位置对应的公网IP地址，将终端装置的位置对应的公网IP地址主动添加到DNS查询请求中并发给DNS服务器，DNS服务器根据DNS查询请求里包含的公网IP地址和域名返回对应的IP地址；进一步地，SMF/UPF还可以根据DNS响应消息，触发SMF插入ULCL/BP优化本地业务访问的路径。可以保证终端装置在新位置就近获取到应用的IP地址，还可以根据业务访问动态插入ULCL/BP，实现本地分流，优化业务访问的路径，提高通信效率。
应理解，上述只是为了帮助本领域技术人员更好地理解本申请实施例，而非要限制本申请实施例的范围。本领域技术人员根据所给出的上述示例，显然可以进行各种等价的修改或变化，例如，上述方法200至1300中某些步骤可以不必须的，或者可以新加入某些步骤等。或者上述任意两种或者任意多种实施例的组合。这样的修改、变化或者组合后的方案也落入本申请实施例的范围内。
应理解，在本申请的各个实施例中，第一、第二等只是为了表示多个对象是不同的。例如第一网元和第二网元只是为了表示出不同的网元。而不应该对网元的本身和数量等产生任何影响，上述的第一、第二等不应该对本申请的实施例造成任何限制。
还应理解，本申请实施例中的方式、情况、类别以及实施例的划分仅是为了描述的方便，不应构成特别的限定，各种方式、类别、情况以及实施例中的特征在不矛盾的情况下可以相结合。
还应理解，在本申请的实施例中涉及的各种数字编号仅为描述方便进行的区分，并不用来限制本申请的实施例的范围。上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任 何限定。
还应理解，上文对本申请实施例的描述着重于强调各个实施例之间的不同之处，未提到的相同或相似之处可以互相参考，为了简洁，这里不再赘述。
还应理解，本申请实施例中，“预定义”可以通过在设备(例如，包括终端装置和网络设备)中预先保存相应的代码、表格或其他可用于指示相关信息的方式来实现，本申请对于其具体的实现方式不做限定。
以上结合图1至图19对本申请实施例的域名系统查询的方法做了详细说明。以下，结合图20至图23对本申请实施例通信装置进行详细说明。
图20示出了本申请实施例的通信装置1400的示意性框图，该通信装置1400可以对应上述方法200中描述的第一网元，也可以是应用于第一网元的芯片或组件，并且，该通信装置1400各模块或单元分别用于执行上述方法200中第一网元所执行的各动作或处理过程，如图20所示，该通信装置1400可以包括：通信单元1410和处理单元1420
通信单元1410，用于接收来自于终端装置的域名系统DNS查询请求，该DNS查询请求包括第一域名，该DNS查询请求用于请求该第一域名对应的互联网协议IP地址。
处理单元1420，用于生成第一请求信息，该第一请求信息包括该终端装置的位置信息以及该第一域名。
通信单元1410还用于：向第二网元发送第一请求信息。
通信单元1410还用于：接收该第二网元发送的响应于该第一请求信息的第一响应信息，该第一响应信息包括该IP地址。
通信单元1410还用于：向该终端装置发送该IP地址。
本申请提供的通信装置，该通信装置将终端装置的位置信息添加到DNS查询请求中发送第二网元，使得第二网元确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址。该通信装置将该IP地址反馈给终端装置。从而使得终端装置通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
可选的，在本申请的一些实施例中，该DNS查询请求还包括目的地址，该目的地址为DNS服务器的地址，该第一请求信息还包括：该目的地址。
可选的，在本申请的一些实施例中，该通信装置为用户面功能网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，通信单元1110还用于：向会话管理网元发送第一通知信息，该第一通知信息用于该会话管理网元为该终端装置选择第一分流点和第一协议数据单元会话锚点PSA。
可选的，在本申请的一些实施例中，该通信装置为会话管理网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，处理单元1120还用于：根据该第一域名、目的地址、与该第一域名对应的该IP地址中的任意一种，为该终端装置选择第一分流节点和第一协议数据单元会话锚点PSA，该目的地址为该DNS服务器的地址。
可选的，在本申请的一些实施例中，该通信装置为用户面功能网元，该第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，通信单元1410还用于： 接收会话管理网元发送该终端装置的位置信息。
可选的，在本申请的一些实施例中，通信单元1410还用于：接收会话管理网元发送的第一规则，其中，该第一域名、目的地址、与该第一域名对应的该IP地址中的任意一种满足该第一规则，该目的地址为该DNS服务器的地址。
可选的，在本申请的一些实施例中，该终端装置的位置信息包括该终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息，或者第一IP地址中的至少一种，其中，该第四网元包括用户面功能网元或者无线接入网网元。该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与该终端装置的位置对应。
应理解，通信装置1400中各单元执行上述相应步骤的具体过程请参照前文中结合图4至图8中以及方法200中的相关实施例的第一网元相关的描述。为了简洁，这里不加赘述。
在一种可能的设计中，该通信装置1400可以是上文方法实施例中的用户面功能网元(例如可以为锚点用户面功能网元PSA)或者为会话管理网元(例如为SMF)，也可以是用于实现上文方法实施例中会话管理网元的功能或者用户面功能网元的功能的芯片。具体地，该通信装置1100可对应于根据本申请实施例的方法400、500、600、700、800、900、1000、1100、1200、1300中的SMF、UPF1、I-SMF或者I-UPF。该通信装置1400可以包括用于执行图10至图19中的方法400至方法1300中的SMF、UPF1、I-SMF或者I-UPF执行的方法的单元。并且，该通信装置1400中的各单元和上述其他操作和/或功能分别为了实现图10至图19中的方法400至方法1300的相应流程。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
可选的，通信单元1410可以包括接收单元(模块)和发送单元(模块)，用于执行前述各个方法实施例中第一网元接收信息和发送信息的步骤。可选的，通信装置1400还可以包括存储单元，用于存储处理单元1420和通信单元1410执行的指令。处理单元1420、通信单元1410和存储单元通信连接，存储单元存储指令，处理单元1420用于执行存储单元存储的指令，通信单元1410用于在处理单元1420的驱动下执行具体的信号收发。
应理解，通信单元1410可以是收发器、输入/输出接口或接口电路等。存储单元可以是存储器。处理单元1420可由处理器实现。如图21所示，通信装置1500可以包括处理器1510、存储器1520和收发器1530。
图20所示的通信装置1400或图21所示的通信装置1500能够实现前述方法200的各个实施例以及图4至图8中的相关实施例的第一网元执行的步骤。或者，还可以实现图10至图19中的方法400至方法1000中的SMF、UPF1、I-SMF或者I-UPF执行的步骤。类似的描述可以参考前述对应的方法中的描述。为避免重复，这里不再赘述。
图22示出了本申请实施例的通信装置1600的示意性框图，该通信装置1600可以对应上述方法300中描述的第三网元，也可以是应用于第三网元的芯片或组件，并且，该通信装置1600各模块或单元分别用于执行上述方法300中第三网元所执行的各动作或处理过程，如图22所示，该通信装置1600可以包括：通信单元1610和处理单元1620
通信单元1610，用于接收第一域名和终端装置的位置信息。
处理单元1620，用于至少根据该第一域名、该终端装置的位置信息确定与该第一域 名对应的IP地址，该IP地址与该终端装置的位置对应。
通信单元1610还用于：发送该IP地址。
本申请提供的通信装置，根据终端装置的位置和请求的域名，确定与终端装置的位置和请求的域名均对应的应用服务器的IP地址，并将该IP地址反馈给终端装置。从而使得终端装置可以通过该应用服务器就近访问业务。避免终端装置通过与自己较远的应用服务器访问业务时的服务受限或者访问不到部分业务问题，提高了终端装置访问业务的质量。并且，由于终端装置可以就近访问业务，降低终端装置访问业务的时延，提高通信效率。
可选的，在本申请的一些实施例中，处理单元1620，还用于：根据所述第一域名、所述终端装置的位置信息，确定与所述第一域名对应的IP地址。其中，该第一信息包括：至少一个域名、与该至少一个域名中的每个域名对应的应用的部署位置、该应用的部署位置对应的IP地址，该至少一个域名包括该第一域名。
可选的，在本申请的一些实施例中，第一信息还可以包括第一IP地址与MEC平台的部署位置或者应用服务器的部署位置之间的对应关系。
可选的，在本申请的一些实施例中，该通信装置为会话管理网元、策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，该通信装置存储该第一信息。
可选的，在本申请的一些实施例中，该通信装置为DNS服务器，通信单元1310还用于：接收策略控制功能网元或者应用功能网元发送的该终端装置的位置信息。
可选的，在本申请的一些实施例中，该通信装置为DNS服务器，通信单元1310具体用于：接收会话管理网元或者用户面功能网元发送的第二请求信息，该第二请求信息包括该第一域名。
可选的，在本申请的一些实施例中，该第二请求信息还包括该终端装置的位置信息。
可选的，在本申请的一些实施例中，该终端装置的位置信息包括该终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息、或者第一IP地址中的至少一种，该第一IP地址指向第一域名对应的应用服务器所在的管理平台，该管理平台的位置与所述终端装置的位置对应。其中，该第四网元包括用户面功能网元或者无线接入网网元。
应理解，通信装置1600中各单元执行上述相应步骤的具体过程请参照前文中结合图9中以及方法300中的相关实施例的第三网元相关的描述。为了简洁，这里不加赘述。
在一种可能的设计中，该通信装置1600可以是上文方法实施例中的策略控制功能网元、应用功能网元、会话管理网元或者DNS服务器中的任意一种。也可以是用于实现上文方法实施例中策略控制功能网元的功能、应用功能网元的功能、会话管理网元的功能或者DNS服务器的功能中的芯片。具体地，该通信装置1300可对应于根据本申请实施例的方法400、500、600、700、800、900、1000、1100、1200、1300中的SMF、I-SMF、PCF、AF或者DNS服务器。该通信装置1600可以包括用于执行图10至图19中的方法400至方法1300中的SMF、I-SMF、PCF、AF或者DNS服务器执行的方法的单元。并且，该通信装置1600中的各单元和上述其他操作和/或功能分别为了实现图10至图19中的方法400至方法1300的相应流程。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
可选的，通信单元1610可以包括接收单元(模块)和发送单元(模块)，用于执行 前述各个方法实施例中第三网元接收信息和发送信息的步骤。可选的，通信装置1600还可以包括存储单元，用于存储处理单元1620和通信单元1610执行的指令。处理单元1620、通信单元1610和存储单元通信连接，存储单元存储指令，处理单元1620用于执行存储单元存储的指令，通信单元1610用于在处理单元1620的驱动下执行具体的信号收发。
应理解，通信单元1610可以是收发器、输入/输出接口或接口电路等。存储单元可以是存储器。处理单元1620可由处理器实现。如图23所示，通信装置1700可以包括处理器1710、存储器1720和收发器1730。
图22所示的通信装置1600或图23所示的通信装置1700能够实现前述方法300的各个实施例以及图9中的相关实施例的第三网元执行的步骤。或者，还可以实现图10至图19中的方法400至方法1300中的SMF、I-SMF、PCF、AF或者DNS服务器执行的步骤。类似的描述可以参考前述对应的方法中的描述。为避免重复，这里不再赘述。
还应理解，以上装置中单元的划分仅仅是一种逻辑功能的划分，实际实现时可以全部或部分集成到一个物理实体上，也可以物理上分开。且装置中的单元可以全部以软件通过处理元件调用的形式实现；也可以全部以硬件的形式实现；还可以部分单元以软件通过处理元件调用的形式实现，部分单元以硬件的形式实现。例如，各个单元可以为单独设立的处理元件，也可以集成在装置的某一个芯片中实现，此外，也可以以程序的形式存储于存储器中，由装置的某一个处理元件调用并执行该单元的功能。这里该处理元件又可以称为处理器，可以是一种具有信号处理能力的集成电路。在实现过程中，上述方法的各步骤或以上各个单元可以通过处理器元件中的硬件的集成逻辑电路实现或者以软件通过处理元件调用的形式实现。
在一个例子中，以上任一装置中的单元可以是被配置成实施以上方法的一个或多个集成电路，例如：一个或多个专用集成电路(application specific integrated circuit，ASIC)，或，一个或多个数字信号处理器(digital signal processor，DSP)，或，一个或者多个现场可编程门阵列(field programmable gate array，FPGA)，或这些集成电路形式中至少两种的组合。再如，当装置中的单元可以通过处理元件调度程序的形式实现时，该处理元件可以是通用处理器，例如中央处理器(central processing unit，CPU)或其它可以调用程序的处理器。再如，这些单元可以集成在一起，以片上系统(system-on-a-chip，SOC)的形式实现。
本申请实施例还提供了一种通信系统，该通信系统包括：上述第一网元和上述第二网元，可选的，该通信系统还包括上述的终端装置、第三网元或者接入网设备中的一种或者多种。或者，该通信系统包括上述的第三网元以及第一网元，可选的，该通信系统还包括上述的终端装置、第二网元或者接入网设备中的一种或者多种。
本申请实施例还提供了一种计算机可读存储介质，用于存储计算机程序代码，该计算机程序包括用于执行上述方法200至方法1300本申请实施例的域名系统查询的方法的指令。该可读介质可以是只读存储器(read-only memory，ROM)或随机存取存储器(random access memory，RAM)，本申请实施例对此不做限制。
本申请还提供了一种计算机程序产品，该计算机程序产品包括指令，当该指令被执行时，以使得该第一网元、第二网元、第三网元或者会话管理网元执行对应于上述方法的第一网元、第二网元或者第三网元的操作。
本申请实施例还提供了一种位于通信装置中的芯片，该芯片包括：处理单元和通信单元，该处理单元，例如可以是处理器，该通信单元例如可以是输入/输出接口、管脚或电路等。该处理单元可执行计算机指令，以使所述通信装置执行上述本申请实施例提供的任一种域名系统查询的方法。
可选地，该计算机指令被存储在存储单元中。
可选地，该存储单元为该芯片内的存储单元，如寄存器、缓存等，该存储单元还可以是该终端内的位于该芯片外部的存储单元，如只读存储器(read-only memory，ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory，RAM)等。其中，上述任一处提到的处理器，可以是一个CPU，微处理器，ASIC，或一个或多个用于控制上述的反馈信息的传输方法的程序执行的集成电路。该处理单元和该存储单元可以解耦，分别设置在不同的物理设备上，通过有线或者无线的方式连接来实现该处理单元和该存储单元的各自的功能，以支持该系统芯片实现上述实施例中的各种功能。或者，该处理单元和该存储器也可以耦合在同一个设备上。
可以理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是ROM、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是RAM，其用作外部高速缓存。RAM有多种不同的类型，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(dynamic RAM，DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synch link DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
本文中术语“系统”和“网络”在本文中常被可互换使用。本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本申请中出现的术语“上行”和“下行”，用于在特定场景描述数据/信息传输的方向，比如，“上行”方向一般是指数据/信息从终端向网络侧传输的方向，或者分布式单元向集中式单元传输的方向，“下行”方向一般是指数据/信息从网络侧向终端传输的方向，或者集中式单元向分布式单元传输的方向，可以理解，“上行”和“下行”仅用于描述数据/信息的传输方向，该数据/信息传输的具体起止的设备都不作限定。
在本申请中可能出现的对各种消息/信息/设备/网元/系统/装置/动作/操作/流程/概念等各类客体进行了赋名，可以理解的是，这些具体的名称并不构成对相关客体的限定，所赋名称可随着场景，语境或者使用习惯等因素而变更，对本申请中技术术语的技术含义的理解，应主要从其在技术方案中所体现/执行的功能和技术效果来确定。
在本申请的各个实施例中，如果没有特殊说明以及逻辑冲突，不同的实施例之间的术语和/或描述具有一致性、且可以相互引用，不同的实施例中的技术特征根据其内在的逻辑关系可以组合形成新的实施例。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请的实施例中的方法可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机程序或指令。在计算机上加载和执行所述计算机程序或指令时，全部或部分地执行本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机程序或指令可以存储在计算机可读存储介质中，或者通过所述计算机可读存储介质进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是集成一个或多个可用介质的服务器等数据存储设备。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个可读存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的可读存储介质包括：U盘、移动硬盘、只读存储器(read-only memory，ROM)、随机存取存储器(random access memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (21)

  1. 一种域名系统查询的方法，其特征在于，包括：
    第一网元接收来自于终端装置的域名系统DNS查询请求，所述DNS查询请求包括第一域名，所述DNS查询请求用于请求所述第一域名对应的互联网协议IP地址；
    所述第一网元向第二网元发送第一请求信息，所述第一请求信息包括所述终端装置的位置信息以及所述第一域名；
    所述第一网元接收所述第二网元发送的响应于所述第一请求信息的第一响应信息，所述第一响应信息包括所述IP地址；
    所述第一网元向所述终端装置发送所述IP地址。
  2. 根据权利权利要求1所述的方法，其特征在于，所述DNS查询请求还包括目的地址，所述目的地址为DNS服务器的地址，
    所述第一请求信息还包括：所述目的地址。
  3. 根据权利要求1或2所述的方法，其特征在于，所述第一网元为用户面功能网元，所述第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，所述方法还包括：
    所述第一网元向会话管理网元发送第一通知信息，所述第一通知信息用于所述会话管理网元为所述终端装置选择第一分流节点或者第一协议数据单元会话锚点PSA。
  4. 根据权利要求1或2所述的方法，其特征在于，所述第一网元为会话管理网元，所述第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，所述方法还包括：
    所述第一网元根据所述第一域名、所述目的地址、与所述第一域名对应的所述IP地址中的任意一种，为所述终端装置选择第一分流节点或者第一协议数据单元会话锚点PSA，所述目的地址为所述DNS服务器的地址。
  5. 根据权利要求1至3中任一项所述的方法，其特征在于，所述第一网元为用户面功能网元，所述第二网元为策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，所述方法还包括：
    所述第一网元接收会话管理网元发送所述终端装置的位置信息。
  6. 根据权利要求3所述的方法，其特征在于，所述方法还包括：
    所述第一网元接收会话管理网元发送的第一规则，其中，所述第一域名、目的地址、与所述第一域名对应的所述IP地址中的任意一种满足所述第一规则，所述目的地址为所述DNS服务器的地址。
  7. 根据权利要求1至6中任一项所述的方法，其特征在于，
    所述终端装置的位置信息包括所述终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息、或者第一IP地址中的至少一种，
    其中，所述第四网元为所述用户面功能网元或者无线接入网网元，所述第一IP地址指向所述第一域名对应的应用服务器所在的管理平台，所述管理平台的位置与所述终端装置的位置对应。
  8. 一种域名系统查询的方法，其特征在于，包括：
    第三网元接收第一域名和终端装置的位置信息，
    所述第三网元至少根据所述第一域名、所述终端装置的位置信息，确定与所述第一域名对应的IP地址，所述IP地址与所述终端装置的位置对应；
    所述第三网元发送与所述第一域名对应的所述IP地址。
  9. 根据权利要求8所述的方法，其特征在于，所述第三网元至少根据所述第一域名、所述终端装置的位置信息，确定与所述第一域名对应的IP地址，包括：所述第三网元根据所述第一域名、所述终端装置的位置信息以及第一信息确定所述IP地址，其中，所述第一信息包括：至少一个域名、与所述至少一个域名中的每个域名对应的应用的部署位置、所述应用的部署位置对应的IP地址，所述至少一个域名包括所述第一域名。
  10. 根据权利要求8或9所述的方法，其特征在于，所述第三网元为会话管理网元、策略控制功能网元、应用功能网元或者DNS服务器中的任意一种，所述第三网元存储有所述第一信息。
  11. 根据权利要求8至10中任一项所述的方法，其特征在于，所述第三网元为DNS服务器，所述方法还包括：
    所述第三网元接收策略控制功能网元或者应用功能网元发送的所述终端装置的位置信息。
  12. 根据权利要求8至11中任一项所述的方法，其特征在于，所述第三网元为DNS服务器，所述第三网元接收第一域名，包括：
    所述第三网元接收会话管理网元或者用户面功能网元发送的第二请求信息，所述第二请求信息包括所述第一域名。
  13. 根据权利要求12所述的方法，其特征在于，所述第二请求信息还包括所述终端装置的位置信息。
  14. 根据权利要求8至13中任一项所述的方法，其特征在于，
    所述终端装置的位置信息包括所述终端装置的跟踪区域标识TAI、数据网络接入标识DNAI、第四网元的标识信息、或者第一IP地址中的至少一种，
    其中，所述第四网元用户面功能网元或者无线接入网网元，所述第一IP地址指向所述第一域名对应的应用服务器所在的管理平台，所述管理平台的位置与所述终端装置的位置对应。
  15. 一种通信装置，其特征在于，包括用于执行如权利要求1至7中任一项所述方法的各个步骤的单元。
  16. 一种通信装置，其特征在于，包括用于执行如权利要求8至14中任一项所述方法的各个步骤的单元。
  17. 一种通信装置，其特征在于，包括至少一个处理器和接口电路，所述接口电路用于所述至少一个处理器获取至少一个存储器中的程序或指令，所述至少一个处理器用于执行所述程序或指令以使所述通信装置执行如权利要求1至7中任一项所述的方法。
  18. 一种通信装置，其特征在于，包括至少一个处理器和接口电路，所述接口电路用于所述至少一个处理器获取至少一个存储器中的程序或指令，所述至少一个处理器用于执行所述程序或指令以使所述通信装置执行如权利要求8至14中任一项所述的方法。
  19. 一种通信系统，其特征在于，包括如权利要求15和16所述的通信装置，或者，如权利要求17和18所述的通信装置。
  20. 一种芯片系统，其特征在于，包括：处理器，用于从存储器中调用并运行计算机程序，使得安装有所述芯片系统的通信设备执行如权利要求1至7中任意一项所述的方法，或者8至14中任意一项所述的方法。
  21. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质中存储有程序，当所述程序被至少一个处理器运行时，如权利要求1至7中任一项所述的方法被执行，或者8至14中任一项所述的方法被执行。
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