WO2022001972A1 - Dns请求的解析方法、通信装置及通信系统 - Google Patents

Dns请求的解析方法、通信装置及通信系统 Download PDF

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Publication number
WO2022001972A1
WO2022001972A1 PCT/CN2021/102811 CN2021102811W WO2022001972A1 WO 2022001972 A1 WO2022001972 A1 WO 2022001972A1 CN 2021102811 W CN2021102811 W CN 2021102811W WO 2022001972 A1 WO2022001972 A1 WO 2022001972A1
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Prior art keywords
local
network
dns
local network
deployed
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PCT/CN2021/102811
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English (en)
French (fr)
Inventor
姚琦
宗在峰
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华为技术有限公司
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Publication of WO2022001972A1 publication Critical patent/WO2022001972A1/zh

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Classifications

    • 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
    • H04L67/01—Protocols
    • H04L67/10—Protocols in which an application is distributed across nodes in the network
    • H04L67/1001—Protocols in which an application is distributed across nodes in the network for accessing one among a plurality of replicated servers
    • H04L67/1036—Load balancing of requests to servers for services different from user content provisioning, e.g. load balancing across domain name servers
    • 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
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/01—Protocols
    • H04L67/02—Protocols based on web technology, e.g. hypertext transfer protocol [HTTP]
    • H04L67/025—Protocols based on web technology, e.g. hypertext transfer protocol [HTTP] for remote control or remote monitoring of applications
    • 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
    • H04L67/01—Protocols
    • H04L67/10—Protocols in which an application is distributed across nodes in the network
    • 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
    • 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
    • H04L61/4552—Lookup mechanisms between a plurality of directories; Synchronisation of directories, e.g. metadirectories

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a DNS request resolution method, a communication device, and a communication system.
  • the terminal device When the terminal device wants to request the service of an application, for example, the user wants to use WeChat service, or use the iQiyi APP to watch videos, the user can click the corresponding function module on the application to trigger the connection between the terminal device and the network.
  • a user plane session is established, and then the terminal device sends a Domain Name System (DNS) request to the network.
  • DNS Domain Name System
  • the request carries the application identifier.
  • the offloading network element After receiving the DNS request, the offloading network element sends the DNS request to the local network or the central network.
  • the DNS server obtains the Internet Protocol (IP) address of the application server through analysis, and then the offloading network element sends the IP address to the terminal device, and the terminal device can access the corresponding application server according to the IP address to obtain the application server. the data content, so as to obtain the service of the application.
  • IP Internet Protocol
  • the present application provides a DNS request parsing method, a communication device, and a communications system, so as to improve the efficiency of parsing DNS requests.
  • an embodiment of the present application provides a method for parsing a DNS request, including: an offloading network element receives a DNS request from a terminal device, where the DNS request includes an application identifier, and the DNS request is used to request that the application identifier corresponds to The Internet Protocol IP address of the application server; the distribution network element determines at least one service network according to the first rule and the configuration information of at least one local network, the service network is deployed with a DNS server, and the configuration information of the local network includes The capability information of the local network, where the capability information of the local network is used to indicate whether the local network is deployed with a local DNS server, and the first rule is a determination rule of the service network; A protocol data unit anchor PSA corresponding to a service network sends the DNS request; the offloading network element receives response information corresponding to the at least one DNS request, and the response information includes the IP address of the application server corresponding to the application identifier address; the distribution network element sends the IP address of the first application server to the
  • the offloading network element can select one or more service networks based on the configured first rule and the configuration information of the local network, and send the received DNS request to the PSA corresponding to the selected one or more service networks, Since DNS servers are deployed in the selected service network, the situation that cannot be resolved can be avoided, thereby improving the resolution success rate of DNS requests.
  • the first rule is preconfigured on the offload network element; or, the offload network element receives the first rule from a session management network element.
  • the configuration information of the at least one local network is pre-configured on the offload network element; or, the offload network element receives the configuration information of the at least one local network from the session management network element. configuration information.
  • the first rule is based on the local DNS server deployment of the local network, the resolution capability of the local DNS server, the application server included in the local network, and the location of the local network. at least one of them is determined.
  • the first rule includes at least one of the following rules:
  • the capability information of the local network is further used to indicate whether the local DNS server supports recursive DNS resolution when the local network is deployed with a local DNS server;
  • the first rule also includes at least one of the following rules:
  • the capability information of the local network is further used to indicate information of application servers deployed in the local network;
  • the first rule further includes at least one of the following rules:
  • the configuration information of the local network further includes location information or service area information of the local network, and the location information or service area information is used by the offloading network element from the at least one A local network closest to the terminal device is selected from the local network.
  • an IP address of the application server closest to the terminal device can be obtained, which can reduce the delay and further improve the user experience.
  • the IP address of the application server received by the offloading network element includes multiple IP addresses
  • the first application server is an application server corresponding to the multiple IP addresses that satisfies the requirements of the application server.
  • the terminal device distance is required by the application server.
  • the application server meeting the distance requirement from the terminal device may be the application server closest to the terminal device, or the application server whose distance from the terminal device is less than a preset threshold.
  • an IP address of the application server closest to the terminal device can be obtained, which can reduce the delay and further improve the user experience.
  • an embodiment of the present application provides a method for parsing a DNS request, including: a session management network element is deployed according to a local DNS server of a local network, the parsing capability of the local DNS server, an application server included in the local network, and an application server included in the local network. at least one of the locations of the local network, and determine the first rule; the session management network element determines the local network that the terminal device can access; the session management network element sends a message to the offloading network element that the terminal device can access
  • the configuration information of the local network and the first rule, the configuration information of the local network includes capability information of the local network, and the capability information of the local network is used to indicate whether the local network is deployed with a local DNS server.
  • an embodiment of the present application provides a communication device, where the device may be an offload network element, and may also be a chip for offload network elements.
  • the device has the function of implementing any of the above-mentioned implementation methods of the first aspect. This function can be implemented by hardware or by executing corresponding software by hardware.
  • the hardware or software includes one or more modules corresponding to the above functions.
  • an embodiment of the present application provides a communication device, where the device may be a session management network element or a chip used for the session management network element.
  • the device has the function of realizing the above-mentioned second aspect. This function can be implemented by hardware or by executing corresponding software by hardware.
  • the hardware or software includes one or more modules corresponding to the above functions.
  • an embodiment of the present application provides a communication device, including a processor and a memory; the memory is used to store computer-executed instructions, and when the device is running, the processor executes the computer-executed instructions stored in the memory, so that the The apparatus performs any of the implementation methods of the first aspect to the second aspect described above.
  • an embodiment of the present application further provides a chip system, including: a processor configured to execute any implementation method of the first aspect to the second aspect.
  • an embodiment of the present application provides a communication apparatus, including a unit or means for performing each step of any implementation method of the first aspect to the second aspect.
  • an embodiment of the present application provides a communication device, including a processor and an interface circuit, where the processor is configured to communicate with other devices through the interface circuit, and execute any implementation method of the first aspect to the second aspect.
  • the processor includes one or more.
  • an embodiment of the present application provides a communication device, including a processor, which is connected to a memory and used to call a program stored in the memory to execute any implementation method of the first aspect to the second aspect.
  • the memory may be located within the device or external to the device.
  • the processor includes one or more.
  • an embodiment of the present application further provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the computer-readable storage medium runs on a computer, the processor causes the processor to execute the above-mentioned first to second aspects any implementation method.
  • the embodiments of the present application further provide a computer program product, the computer product includes a computer program, and when the computer program runs, any implementation method of the above-mentioned first aspect to the second aspect is executed.
  • an embodiment of the present application further provides a communication system, including: a session management network element configured to deploy according to the local DNS server of the local network, the resolution capability of the local DNS server, and the application server included in the local network and at least one of the location of the local network, determine the first rule; determine the local network that the terminal device can access; send the configuration information of the local network that the terminal device can access and the first rule to the offloading network element
  • the configuration information of the local network includes capability information of the local network, and the capability information of the local network is used to indicate whether the local network is deployed with a local DNS server.
  • the offloading network element is configured to receive the configuration information of the local network and the first rule from the session management network element.
  • FIG. 1 is a schematic diagram of a communication system provided by an embodiment of the present application.
  • Figure 2(a) is a schematic diagram of the 5G network architecture
  • Figure 2(b) is another schematic diagram of the 5G network architecture
  • FIG. 3 is an exemplary diagram of a plurality of PSA scenarios
  • FIG. 4 is a schematic diagram of a method for parsing a DNS request provided by an embodiment of the present application
  • FIG. 5 is a schematic diagram of a communication device according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of another communication device provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of still another communication apparatus provided by an embodiment of the present application.
  • the present application provides a communication system, which includes a distribution network element and a session management network element.
  • a session management network element configured to determine the first rule according to at least one of the deployment of the local DNS server of the local network, the resolution capability of the local DNS server, the application server included in the local network, and the location of the local network; Determine the local network that the terminal device can access; send the configuration information of the local network that the terminal device can access and the first rule to the offloading network element, where the configuration information of the local network includes the capability information of the local network , the capability information of the local network is used to indicate whether the local network is deployed with a local DNS server.
  • the offloading network element is configured to receive the configuration information of the local network and the first rule from the session management network element.
  • the offloading network element is further configured to receive a DNS request from the terminal device, where the DNS request includes an application identifier, and the DNS request is used to request an application corresponding to the application identifier Internet Protocol IP address of the server; according to the first rule and the configuration information of the local network, determine at least one service network, the service network is deployed with a DNS server; anchor to the protocol data unit corresponding to the at least one service network point PSA to send the DNS request; receive response information corresponding to the at least one DNS request, the response information includes the IP address of the application server; send the IP address of the first application server to the terminal device, the offload network
  • the IP address of the application server corresponding to the application identifier received by the meta includes the IP address of the first application server.
  • the deployment of the DNS server on the service network includes the following scenarios: the DNS server may be deployed in the service network, may also be deployed on the UPF/PSA serving the service network, or may be deployed on the UPF/PSA serving the service network.
  • the location between the PSA and the service network, and the deployment location of the DNS server are not limited, and the service network may be a local network/edge network, or a central network.
  • the first rule includes at least one of the following rules:
  • the capability information of the local network is further used to indicate whether the local DNS server supports recursive DNS resolution when the local network is deployed with a local DNS server;
  • the first rule further includes At least one of the following rules:
  • the capability information of the local network is further used to indicate information of application servers deployed in the local network;
  • the first rule further includes at least one of the following rules:
  • the configuration information of the local network further includes location information or service area information of the local network, and the location information or service area information is used by the offloading network element from the at least one A local network closest to the terminal device is selected from the local network.
  • the IP address of the application server received by the offloading network element includes multiple IP addresses
  • the first application server is an application server corresponding to the multiple IP addresses that satisfies the requirements of the application server.
  • the terminal device distance is required by the application server.
  • the configuration information of the local network further includes priority information of the local network, and the priority information is used by the offloading network element to select a priority from the at least one local network. the highest-level local network.
  • the system shown in Figure 1 can be used in the fifth generation (5G) network architecture shown in Figure 2(a) or Figure 2(b), of course, it can also be used in future network architectures, such as the sixth generation (6th generation, 6G) network architecture, etc., which are not limited in this application.
  • 5G fifth generation
  • 6G sixth generation
  • FIG. 2( a ) is a schematic diagram of the 5G network architecture.
  • the network element or entity corresponding to the session management network element in FIG. 1 may be the session management function (session management function, SMF) network element in the 5G network architecture shown in FIG. 2(a), and the offloading network element in FIG. 1
  • the corresponding network element or entity may be a user plane function (user plane function, UPF) network element in the 5G network architecture shown in Figure 2(a).
  • FIG. 2( b ) is a schematic diagram of the 5G network architecture.
  • the network element or entity corresponding to the session management network element in FIG. 1 may be the SMF network element in the 5G network architecture shown in FIG. 2(a), and the network element or entity corresponding to the offloading network element in FIG. 1 may be The Uplink Classifier (ULCL) network element in the 5G network architecture shown in Figure 2(a).
  • ULCL Uplink Classifier
  • the 5G network architecture shown in Figure 2(a) can include three parts, namely the terminal equipment part, the data network (DN) and the operator network part. The following briefly describes the functions of some of the network elements.
  • the operator network may include one or more of the following network elements: Authentication Server Function (AUSF) network element, Network Exposure Function (NEF) network element, Policy Control Function (Policy Control Function) Function, PCF) network element, unified data management (unified data management, UDM), unified database (Unified Data Repository, UDR), application function (Application Function, AF) network element, access and mobility management function (Access and Mobility) Management Function, AMF) network elements, SMF network elements, radio access network (radio access network, RAN) equipment and UPF network elements, etc.
  • AUSF Authentication Server Function
  • NEF Network Exposure Function
  • Policy Control Function Policy Control Function
  • PCF Policy Control Function
  • UDM unified data management
  • UDR Unified Data Repository
  • AMF Access and Mobility Management Function
  • SMF radio access network
  • radio access network radio access network
  • RAN radio access network
  • the terminal device in this embodiment of the present application may be a device for implementing a wireless communication function.
  • the terminal device may be a user equipment (user equipment, UE), an access terminal, a terminal unit, a terminal station, a mobile station, a mobile station in a 5G network or a future evolved public land mobile network (public land mobile network, PLMN).
  • PLMN public land mobile network
  • the access terminal may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a wireless communication Functional handheld devices, computing devices or other processing devices connected to wireless modems, in-vehicle devices or wearable devices, virtual reality (VR) end devices, augmented reality (AR) end devices, industrial control (industrial) wireless terminal in control), wireless terminal in self-driving, wireless terminal in remote medical, wireless terminal in smart grid, wireless terminal in transportation safety Terminals, wireless terminals in smart cities, wireless terminals in smart homes, etc. Terminals can be mobile or stationary.
  • SIP session initiation protocol
  • WLL wireless local loop
  • PDA personal digital assistant
  • a wireless communication Functional handheld devices computing devices or other processing devices connected to wireless modems, in-vehicle devices or wearable devices, virtual reality (VR) end devices, augmented reality (AR) end devices, industrial control (industrial) wireless terminal in control), wireless terminal in self-driving,
  • the above-mentioned terminal device can establish a connection with the operator network through an interface (eg, N1, etc.) provided by the operator network, and use the data and/or voice services provided by the operator network.
  • the terminal device can also access the DN through the operator's network, and use the operator's service deployed on the DN and/or the service provided by a third party.
  • the above-mentioned third party may be a service party other than the operator's network and the terminal device, and may provide other data and/or voice services for the terminal device.
  • the specific expression form of the above third party can be specifically determined according to the actual application scenario, and is not limited here.
  • RAN is a sub-network of an operator's network, and is an implementation system between service nodes and terminal equipment in the operator's network.
  • the terminal device To access the operator's network, the terminal device first passes through the RAN, and then can be connected to the service node of the operator's network through the RAN.
  • the RAN device in this application is a device that provides a wireless communication function for a terminal device, and the RAN device is also called an access network device.
  • the RAN equipment in this application includes but is not limited to: next-generation base station (g nodeB, gNB), evolved node B (evolved node B, eNB), radio network controller (radio network controller, RNC), node B in 5G (node B, NB), base station controller (BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (baseBand unit, BBU), transmission point (transmitting and receiving point, TRP), transmitting point (transmitting point, TP), mobile switching center, etc.
  • next-generation base station g nodeB, gNB
  • evolved node B evolved node B
  • eNB evolved node B
  • RNC radio network controller
  • node B in 5G node B, NB
  • base station controller BSC
  • base transceiver station base transceiver station
  • BTS home base station
  • base station for example, home
  • the AMF network element mainly performs functions such as mobility management and access authentication/authorization. In addition, it is also responsible for transferring user policies between UE and PCF.
  • the SMF network element mainly performs functions such as session management, execution of control policies issued by PCF, selection of UPF, and allocation of UE IP addresses.
  • the UPF network element as the interface UPF with the data network, completes functions such as user plane data forwarding, session/flow-level accounting statistics, and bandwidth limitation.
  • the UDM network element is mainly responsible for the management of contract data, user access authorization and other functions.
  • UDR is mainly responsible for the access function of contract data, policy data, application data and other types of data.
  • the NEF network element is mainly used to support the opening of capabilities and events.
  • the AF network element mainly conveys the requirements of the application side to the network side, such as quality of service (Quality of Service, QoS) requirements or user status event subscriptions.
  • the AF may be a third-party functional entity or an application service deployed by an operator, such as an IP Multimedia Subsystem (IP Multimedia Subsystem, IMS) voice call service.
  • IP Multimedia Subsystem IP Multimedia Subsystem
  • the PCF network element is mainly responsible for policy control functions such as charging for sessions and service flow levels, QoS bandwidth guarantee and mobility management, and UE policy decision-making.
  • AUSF network element It is mainly responsible for authenticating users to determine whether to allow users or devices to access the network.
  • a DN is a network outside the operator's network.
  • the operator's network can access multiple DNs, and multiple services can be deployed on the DNs, which can provide data and/or voice services for terminal devices.
  • the DN is a private network of a smart factory
  • the sensors installed in the workshop of the smart factory can be terminal devices
  • the control server of the sensor is deployed in the DN, and the control server can provide services for the sensor.
  • the sensor can communicate with the control server, obtain the instruction of the control server, and transmit the collected sensor data to the control server according to the instruction.
  • the DN is an internal office network of a company.
  • the mobile phones or computers of employees of the company can be terminal devices, and the mobile phones or computers of employees can access information and data resources on the internal office network of the company.
  • N7 the interface between the PCF and the SMF, used to issue a protocol data unit (protocol data unit, PDU) session granularity and a business data flow granularity control policy.
  • protocol data unit protocol data unit
  • N15 the interface between the PCF and the AMF, used for delivering UE policies and access control related policies.
  • N5 the interface between the AF and the PCF, used for application service request delivery and network event reporting.
  • N4 The interface between the SMF and the UPF, used to transmit information between the control plane and the user plane, including controlling the distribution of forwarding rules for the user plane, QoS control rules, traffic statistics rules, etc., and information on the user plane report.
  • N11 the interface between the SMF and the AMF, used to transfer the PDU session tunnel information between the RAN and the UPF, the control message sent to the UE, the radio resource control information sent to the RAN, and the like.
  • N2 the interface between the AMF and the RAN, used to transmit radio bearer control information from the core network side to the RAN, etc.
  • N1 the interface between the AMF and the terminal device, used for delivering QoS control rules and the like to the UE.
  • N8 the interface between the AMF and the UDM, for the AMF to obtain the access and mobility management related subscription data and authentication data from the UDM, and the AMF to register the UE's current mobility management related information to the UDM.
  • N10 the interface between the SMF and the UDM, for the SMF to obtain the session management related subscription data from the UDM, and the SMF to register the UE's current session related information to the UDM.
  • N35 an interface between the UDM and the UDR, used for the UDM to obtain user subscription data information from the UDR.
  • N36 an interface between the PCF and the UDR, for the PCF to obtain the policy-related subscription data and application data-related information from the UDR.
  • N12 the interface between AMF and AUSF, used for AMF to initiate an authentication process to AUSF, which can carry SUCI as a contract identifier;
  • N13 the interface between the UDM and the AUSF, for the AUSF to obtain the user authentication vector from the UDM to execute the authentication process.
  • network elements or functions may be network elements in hardware devices, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (eg, a cloud platform).
  • a platform eg, a cloud platform
  • the foregoing network element or function may be implemented by one device, or may be implemented jointly by multiple devices, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application.
  • the session management network element and user plane network element in this application can be SMF and UPF (such as ULCL, PSA1, PSA2) in Fig. 2(a) or Fig. 2(b) respectively, or can be future communication such as 6G network
  • SMF and UPF such as ULCL, PSA1, PSA2
  • 6G network This application does not limit the network element having the functions of the above-mentioned SMF and UPF.
  • the present application takes as an example that the session management network element and the user plane network element are the above-mentioned SMF and UPF, respectively.
  • 5G There is only one UPF in the 5G network architecture shown in Figure 2(a) above.
  • 5G also supports the insertion of one or more protocol data unit anchors (PDU Session Anchors) on the user plane path of a PDU session.
  • PSA protocol data unit anchors
  • PSA to support the connection to the local network (or called edge data network, or called Mobile Edge Compute (MEC) network, or called local data network, or called MEC), thereby making Terminal devices can access applications in the local data network nearby.
  • MEC Mobile Edge Compute
  • FIG. 2(a) On the basis of Figure 2(a), multiple UPFs can be introduced to obtain the 5G network architecture shown in Figure 2(b). Among them, some network elements in Fig. 2(a) are not shown in Fig. 2(b).
  • the various UPFs introduced include: ULCL UPF, PSA UPF1 and PSA UPF-2. It should be noted that Figure 2(b) is only an example, and in practical applications, the number of PSAs is not limited, and may be one, two, or more than two.
  • the branching network element may be a ULCL UPF
  • the ULCL UPF may also be referred to as a ULCL, a branching point (Branching Point, BP), a BP UPF, and the like, which are all represented by ULCL below.
  • PSA UPF may also be referred to as UPF PSA or PSA, etc., and is represented by PSA below. Therefore, the above-mentioned PSA UPF1 and PSA UPF2 can also be referred to as PSA1 and PSA2.
  • the ULCL is used to distribute the uplink data packets received from the terminal equipment to PSA1 or PSA2 according to the distribution rules, and send the downlink data packets received from the PSA1 or PSA2 to the terminal equipment.
  • the DN may be a DN located in a central data center (Data Center, DC).
  • the PSA1 may also be called a center PSA (center PSA, C-PSA) or a remote PSA.
  • the local DN may be a DN located in the local DC (ie, the MEC network).
  • the PSA2 may also be called a local PSA (local PSA, L-PSA).
  • the SMF can insert the UPF into the session path as an L-PSA, so that the terminal device can access the application in the local DN nearby.
  • Figure 2(b) above only shows one L-PSA (ie, PSA2), and a plurality of L-PSAs may also be included in practical applications.
  • the ULCL can be connected to multiple L-PSAs.
  • the connection of two L-PSAs ie, L-PSA1 and L-PSA2 is taken as an example.
  • L-PSA1 is connected to local network 1
  • L-PSA2 is connected to local network 2
  • C-PSA is connected to a central network (also called central data network, central DC, remote network, remote data network, etc.).
  • the DNS server is deployed in the local network 1
  • the DNS server is not deployed in the local network 2
  • the DNS server is deployed in the central network.
  • the DNS server deployed in the local network may also be called an edge DNS server or a local (Local) DNS server.
  • L-DNS is used to represent the local DNS server in the local network
  • the DNS server deployed in the central network may also be called the center.
  • C-DNS is used to represent the central DNS server in the central network.
  • L-DNS can be deployed together with the UPF that provides services for the local network.
  • local network 1 can be deployed in one with L-PSA1
  • local network 2 can be deployed in one with L-PSA2.
  • ULCL can be deployed in one with a certain L-PSA, such as ULCL and L-PSA1 in one deployment.
  • the L-DNS deployed in the local network can be used to resolve DNS requests corresponding to application servers in the local network.
  • the L-DNS deployed in the local network may be connected to the C-DNS server deployed in the central network (that is, it can communicate with each other), or it may not be connected to the C-DNS deployed in the central network (that is, it cannot communicate with each other).
  • the terminal device wants to request the service of an application, for example, the user wants to use WeChat service, or use the iQiyi APP to watch videos
  • the user can click the corresponding function module on the application to trigger the connection between the terminal device and the network.
  • a user plane session is established, and then the terminal device sends a DNS request to the network.
  • the request carries the application identifier (such as a fully qualified domain name (FQDN)).
  • FQDN fully qualified domain name
  • the ULCL After receiving the DNS request, the ULCL sends the DNS request to a certain PSA, for example, is sent to L-PSA1, and then L-PSA1 sends a DNS request to L-DNS in local network 1, the L-DNS queries the IP address corresponding to the application identifier, and sends the IP address to L-PSA1,
  • the L-PSA1 sends the IP address to the ULCL, and the ULCL sends the IP address to the terminal device through the RAN, so that the terminal device can access the corresponding application server according to the IP address to obtain the data content of the application server, thereby obtaining the application's data content.
  • the IP address here is the IP address of the application server corresponding to the application identifier, and specifically may be the IP address of the application server in the central network and/or the IP address in one or more local networks.
  • the application is WeChat
  • the obtained IP address is the IP address of the WeChat application server.
  • the DNS server stores the mapping relationship between the application identifier of the application server and the IP address.
  • the DNS server of the local network 1 stores the WeChat domain name and the IP address of the WeChat application server.
  • the application server of the same application can be deployed on the central network.
  • the application server can also be deployed on the central network while deploying the application server on the central network. in one or more local networks.
  • the Tencent application server can be deployed on the central network, and the Tencent application server can also be deployed on the local network 1 and/or the local network 2 at the same time.
  • the ULCL When the ULCL receives the DNS request (which carries the application identifier) and needs to send the DNS request to a PSA, the following situations exist:
  • ULCL sends a DNS request to L-PSA2, but the local network corresponding to L-PSA2 does not have a DNS server deployed, so L-PSA2 cannot send the DNS request to the corresponding DNS server, resulting in the DNS request cannot be resolved. .
  • a DNS server is deployed in the local network corresponding to the PSA
  • the DNS server in the local network can resolve DNS requests.
  • the scenario 2 can be further divided into the following scenario 2.1 and scenario 2.2.
  • the application server corresponding to the application ID in the DNS request is deployed in the local network corresponding to the PSA
  • ULCL sends DNS requests to L-PSA1, and the local network corresponding to L-PSA1 deploys a DNS server, so L-PSA1 can send DNS requests to the DNS server in local network 1, and the DNS server can DNS requests are resolved.
  • the DNS server of the local network 1 stores the correspondence between the application identifier and the IP address of the application server, so the DNS server can successfully resolve Get the IP address of the application server.
  • ULCL sends DNS requests to L-PSA1, and the local network 1 corresponding to L-PSA1 has deployed a DNS server, so L-PSA1 can send DNS requests to the DNS server in local network 1, and the DNS server can The DNS request is resolved.
  • the DNS server of the local network 1 may not store the correspondence between the application identifier and the IP address of the application server, so the DNS server cannot succeed. Resolve to obtain the IP address of the application server.
  • this case 2.2 further according to whether there is a connection (ie, interworking) between the DNS server in the local network and the DNS server in the central network, this case 2.2 can be divided into the following case 2.2.1 and case 2.2.2.
  • the DNS server deployed in the central network When there is a connection between the DNS server deployed in the MEC and the DNS server deployed in the central network, when the DNS server in the local network fails to resolve the application identifier in the DNS request, the DNS request can be sent to the DNS server in the central network , the DNS server in the central network parses the application identifier in the DNS request. That is, in this case, the DNS server in the local network supports recursive resolution.
  • the DNS server deployed in the central network does not specifically refer to the C-DNS in Figure 3, but generally refers to the DNS server that has DNS resolution capability and has an interface with the DNS server in the local network, that is, the DNS server in the local network. After the DNS server sends the DNS request to the DNS server, the DNS server can resolve the DNS request.
  • the DNS server in the central network is deployed with the application server corresponding to the application identifier, so the resolution can be successful.
  • the DNS server in the central network stores a mapping relationship between an application identifier and the IP addresses of multiple application servers, where the multiple application servers include an application server located in the central network and an application server located in the local network.
  • the corresponding IP address is sent to the DNS server deployed in the local network, and then sent to the ULCL by the L-PSA corresponding to the local network, and further sent to the terminal device.
  • the IP address parsed by the DNS server in the central network may not be the optimal IP address, that is, the application server corresponding to the IP address may not be the application that is closest or nearer to the terminal device. server, which may result in a poor user experience.
  • the DNS server in the local network fails to resolve the application identifier in the DNS request
  • the DNS request can be sent to the DNS server in the central network, and the DNS request also carries the location information of the terminal device
  • the DNS server of the central network can parse the DNS request based on the location information of the terminal device, and the IP address obtained by parsing is closer to the terminal device.
  • the above are various situations that may occur when ULCL sends DNS requests to different PSAs.
  • the DNS server in the local network can be resolved, it should be resolved by the DNS server of the local network.
  • the DNS server can obtain the IP address of the application server closest to the terminal device, and if it is resolved by the DNS server of the central network, on the one hand, the path is long, causing delay, and on the other hand, the IP address obtained by the DNS server of the central network
  • the corresponding application server may not be the application server closest to the terminal device, resulting in poor user experience.
  • the present application provides a DNS request resolution method.
  • the terminal device is a UE as an example for description. This embodiment is described in conjunction with the network architecture shown in FIG. 3 .
  • the embodiments of the present application are not limited to the network architecture shown in FIG. 3 .
  • the embodiments of the present application may be applicable to a situation where one local network, two local networks, or more than two local networks are deployed.
  • the method includes the following steps:
  • Step 401 the SMF configures the first rule and the configuration information of the local network.
  • the local network here can be one or more local networks.
  • the local network may also be referred to as an edge network, MEC network, MEC, local data network, or the like.
  • the first rule (also referred to as DNS request forwarding rule, forwarding rule, determination rule, etc.) may be configured on the SMF by the administrator through the network management system, or may also be determined by the SMF. For example, the SMF determines the first rule according to at least one of the L-DNS deployment of the local network, the resolution capability of the L-DNS, the application server included in the local network, and the location of the local network.
  • the configuration information of the local network may be configured on the SMF by the administrator through the network management system, or may also be determined by the SMF.
  • the configuration information of the local network includes at least capability information of the local network, and the capability information of the local network is used to indicate whether the local network is deployed with L-DNS.
  • the capability information of the local network is further used to indicate whether the L-DNS supports recursive DNS resolution when the local network is deployed with the L-DNS. Among them, when there is an interface between the L-DNS and the C-DNS, the L-DNS supports recursive resolution.
  • the capability information of the local network is also used to indicate the information of the application server deployed on the local network.
  • the configuration information of the local network further includes location information or service area information of the local network.
  • the location information or service area information of the local network may be represented by a Tracking Area Indicator (TAI), which is used to indicate the location where the local network is located.
  • TAI Tracking Area Indicator
  • Step 402 the UE creates a PDU session.
  • the SMF has not inserted the ULCL in the PDU session, and the current user plane path of the PDU session is: UE ⁇ ->RAN ⁇ ->C-PSA.
  • Step 403 the SMF is inserted into the ULCL.
  • the SMF can be inserted into the ULCL during the session creation by the UE, or can be inserted dynamically after the UE creates the session.
  • the triggering event that triggers the insertion of the SMF into the ULCL may be: the SMF detects that the UE moves, the SMF receives a DNS request from the C-PSA, or receives a notification from the PCF, and so on.
  • Step 404 the SMF sends the first rule and the configuration information of the local network to the ULCL. Accordingly, the ULCL may receive the first rule and the configuration information of the local network.
  • SMF creates an N4 session between SMF and ULCL, and then sends the first rule and the configuration information of the local network to the ULCL through the N4 session.
  • the ULCL can determine to send the received DNS request to the ULCL according to the first rule and the configuration information of the local network.
  • the corresponding UPF where the UPF may be L-PSA and/or C-PSA.
  • the SMF sends the first rule and the configuration information of the multiple local networks to the ULCL .
  • the SMF may determine the local network that the UE that creates the PDU session can access, and then sends the first rule and the configuration information of the local network that the UE can access to the ULCL.
  • Step 405 the ULCL configures the first rule and the configuration information of the local network.
  • the ULCL After receiving the first rule and the configuration information of the local network, the ULCL configures the first rule and the configuration information of the local network on the ULCL.
  • the ULCL After configuring the first rule and the configuration information of the local network on the ULCL, the ULCL can determine which UPF to forward the received DNS request to based on the first rule and the configuration information of the local network.
  • the first rule on the ULCL may also be pre-configured on the ULCL, for example, may be pre-configured by an administrator through a network management system.
  • the first rule on the ULCL is preconfigured on the ULCL, it is not necessary to configure the first rule on the ULCL through the SMF.
  • the configuration information of the local network on the ULCL may also be pre-configured on the ULCL, for example, it may be pre-configured by an administrator through a network management system.
  • the configuration information of the local network on the ULCL is pre-configured on the ULCL, it is not necessary to configure the configuration information of the local network to the ULCL through the SMF.
  • Step 406a the SMF is inserted into the L-PSA1 to create a tunnel between the ULCL and the L-PSA1.
  • L-PSA1 in order to establish a user plane connection with the local network 1, L-PSA1 can be inserted into the user plane path of the UE's PDU session, and a tunnel between ULCL and L-PSA1 can be created to establish The user plane path is: UE ⁇ ->RAN ⁇ ->L-PSA1 ⁇ ->Local network 1.
  • Step 406b the SMF is inserted into the L-PSA2 to create a tunnel between the ULCL and the L-PSA2.
  • L-PSA2 in order to establish a user plane connection with the local network 2, L-PSA2 can be inserted into the user plane path of the UE's PDU session, and a tunnel between ULCL and L-PSA2 can be created to establish The user plane path is: UE ⁇ ->RAN ⁇ ->L-PSA2 ⁇ ->Local network 2.
  • Step 407 the ULCL receives the DNS request.
  • the DNS request is sent by the UE to the RAN, and the RAN sends the DNS request to the ULCL.
  • the DNS request includes the application identifier, and the DNS request is used to request to query the IP address of the application server corresponding to the application identifier.
  • Step 408 the ULCL determines at least one serving network for receiving the DNS request.
  • the service network here can be a local network or a central network.
  • the service network is deployed with DNS servers.
  • L-DNS when the service network is a local network, L-DNS is deployed.
  • one or more application servers ie, local application servers
  • a local network corresponds to one or more L-PSAs, or the one or more L-PSAs provide services for the local network.
  • the L-PSA and the local network can be deployed together or separately.
  • the L-DNS supports recursive resolution, that is, the received DNS request can be forwarded to the L-DNS for resolution.
  • C-DNS When the service network is the central network, C-DNS is deployed.
  • one or more application servers ie, central application servers
  • One central network corresponds to one or more C-PSAs, or the one or more C-PSAs provide services for the central network.
  • the C-PSA and the central network can be deployed together or separately.
  • the C-DNS can receive the DNS request sent by the one or the local network, and after parsing the DNS request, parse the DNS request. The resulting IP address is sent to the L-DNS of the local network.
  • step 408 the ULCL determines which DNS server or servers in the network need to resolve the DNS request.
  • the ULCL can determine at least one serving network based on the first rule and configuration information of at least one local network, and then can determine the PSA (such as L-PSA and/or C-PSA) corresponding to the at least one serving network respectively.
  • PSA such as L-PSA and/or C-PSA
  • the first rule configured on the ULCL includes but is not limited to at least one of the following:
  • the first rule 1 If the local network accessible to the UE does not deploy L-DNS, send the DNS request to the central network.
  • the DNS request is sent to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • the DNS request is not sent to the L-PSA corresponding to the local network where L-DNS is not deployed, but is directly sent to the C-PSA corresponding to the central network, which can improve the resolution success rate of the DNS request, thereby improving the parsing efficiency.
  • the first rule 2 is to send the DNS request to the local network in which the L-DNS is deployed in the local network accessible to the UE, and to the central network.
  • the priorities among the multiple local networks and the central network can be predefined, so that when the ULCL receives IP addresses from multiple networks, it can select one from the multiple received IP addresses according to the priorities. .
  • the first rule 3 Send the DNS request to one or more local networks where L-DNS is deployed in the local networks accessible to the UE.
  • priorities among the multiple local networks may be predefined, so that when the ULCL receives IP addresses from multiple networks, it may select one from the multiple received IP addresses according to the priorities.
  • the first The rules may further include, but are not limited to, at least one of the following:
  • the first rule 4 If there are multiple local networks in the local network accessible to the UE that deploy L-DNS supporting recursive DNS resolution, select one local network and send the DNS request to the selected local network.
  • the DNS request is sent to the L-PSA corresponding to the selected local network, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, instead of sending it to the L-PSAs corresponding to multiple local networks, that is, it only sends the DNS request to the L-PSA corresponding to multiple local networks each time.
  • a network request resolves a DNS request, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the DNS request is sent to the L-PSA corresponding to the local network where the L-DNS supporting recursive DNS resolution is deployed, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the first rule 5 If there is only one local network in which the UE can access the local network where the L-DNS supporting recursive DNS resolution is deployed, the DNS request is sent to the local network.
  • the ULCL sends the DNS request to the L-PSA corresponding to the local network
  • the L-PSA sends the DNS request to the L-DNS in the local network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, instead of sending it to the L-PSAs corresponding to multiple local networks, that is, it only sends the DNS request to the L-PSA corresponding to multiple local networks each time.
  • a network request resolves a DNS request, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the DNS request is sent to the L-PSA corresponding to the local network where the L-DNS supporting recursive DNS resolution is deployed, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the first rule 6 If there are multiple local networks in the local network accessible to the UE, where L-DNS supporting recursive DNS resolution is deployed, the DNS request is sent to the multiple local networks.
  • priorities among the multiple local networks may be pre-defined, so that when the ULCL receives IP addresses from multiple local networks, one may be selected from the multiple received IP addresses according to the priorities.
  • the ULCL can send the DNS request to the L-PSAs corresponding to the multiple local networks respectively, and the L-PSAs respectively send the DNS requests to the L-DNS in the corresponding local networks for resolution.
  • the success rate of DNS resolution can be improved, thereby improving the resolution efficiency.
  • the DNS request is sent to the L-PSA corresponding to the local network where the L-DNS supporting recursive DNS resolution is deployed, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the first rule 7 If there are multiple local networks in the local network accessible to the UE that deploy L-DNS that does not support recursive DNS resolution, select one local network and send the DNS request to the selected local network.
  • the ULCL sends the DNS request to the L-PSA corresponding to the selected one of the local networks, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution.
  • the resolution fails, one other local network can be selected from the above multiple local networks, and the DNS request can be sent to the L-PSA corresponding to the other local network, and the L-PSA will send the DNS request to the other local network.
  • L-DNS to resolve.
  • the DNS request is sent to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network or the C-PSA corresponding to the central network, rather than to the L-PSAs corresponding to multiple local networks, the That is, only one network request is made to resolve DNS requests at a time, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the first rule 8 If there is only one local network that can be accessed by the UE and has deployed L-DNS that does not support recursive DNS resolution, send a DNS request to the local network.
  • the ULCL sends the DNS request to the L-PSA corresponding to the local network, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution. If the resolution fails, the DNS request is sent to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network or the C-PSA corresponding to the central network, rather than to the L-PSAs corresponding to multiple local networks, the That is, only one network request is made to resolve DNS requests at a time, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the first rule 9 If there are multiple local networks in the local networks accessible to the UE, and L-DNS that does not support recursive DNS resolution is deployed in multiple local networks, the DNS request is sent to the multiple local networks.
  • priorities among the multiple local networks may be pre-defined, so that when the ULCL receives multiple IP addresses, it may select one from the multiple received IP addresses according to the priorities.
  • the ULCL sends the DNS requests to the L-PSAs corresponding to the multiple local networks, and the L-PSAs send the DNS requests to the L-DNS in the corresponding local networks for resolution. If the L-DNS corresponding to the multiple local networks fails to resolve, the DNS request is sent to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • the ULCL sends the received DNS request to the L-PSAs corresponding to multiple local networks, instead of only sending it to the L-PSA corresponding to one local network, that is, to multiple local networks at a time
  • the request resolves the DNS request, so the success rate of DNS resolution can be improved, thereby improving the resolution efficiency.
  • the capability information of the local network in the configuration information of the local network configured on the ULCL is also used to indicate the information of the application servers deployed on the local network
  • the information of the application servers deployed on the local network is used to indicate which applications are deployed in the local network.
  • the application server for example, can be represented by an application identifier (such as FQDN) to indicate the deployed application server.
  • the first rule configured on the ULCL may further include, but is not limited to, at least one of the following:
  • the first rule 10 If there are multiple local networks in the local network accessible to the UE, and the application servers corresponding to the application identifiers are deployed on the multiple local networks, and the L-DNS is deployed on the multiple local networks, select a local network from the multiple local networks. network, which sends DNS requests to the selected local network.
  • the ULCL sends the DNS request to the L-PSA corresponding to the selected local network, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, instead of sending it to the L-PSAs corresponding to multiple local networks, that is, it only sends the DNS request to the L-PSA corresponding to multiple local networks each time.
  • a network request resolves a DNS request, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • an application server corresponding to the application identifier in the DNS request is deployed on the local network, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the first rule 11 If there is only one local network that the UE can access has an application server corresponding to the application identifier deployed, and the local network is deployed with L-DNS, send a DNS request to the local network.
  • the ULCL sends the DNS request to the L-PSA corresponding to the local network
  • the L-PSA sends the DNS request to the L-DNS in the local network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, instead of sending it to the L-PSAs corresponding to multiple local networks, that is, it only sends the DNS request to the L-PSA corresponding to multiple local networks each time.
  • a network request resolves a DNS request, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • an application server corresponding to the application identifier in the DNS request is deployed on the local network, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the first rule 12 If there are one or more local networks that can be accessed by the UE, and an application server corresponding to the application identifier is deployed in one or more local networks, and the one or more local networks do not deploy L-DNS, send a DNS request. to the central network.
  • the ULCL sends the DNS request to the C-PSA corresponding to the central network
  • the C-PSA sends the DNS request to the C-DNS in the central network for resolution.
  • the location information or service area information of the one or more local networks is also sent to the C-DNS, so that the C-DNS can select a distance according to the location information or service area information of the one or more local networks.
  • UE's nearest application server is also sent to the C-DNS, so that the C-DNS can select a distance according to the location information or service area information of the one or more local networks.
  • the ULCL since the ULCL only sends the received DNS request to the C-PSA corresponding to the central network, instead of sending it to the PSAs corresponding to multiple networks, that is, only one network is requested for resolution at a time. Therefore, the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the central network since the central network is deployed with an application server corresponding to the application identifier in the DNS request, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • not sending DNS requests to the local network where L-DNS is not deployed can reduce unnecessary signaling overhead.
  • the first rule 13 If the local network accessible to the UE does not deploy an application server corresponding to the application identifier, send a DNS request to the central network.
  • the ULCL sends the DNS request to the C-PSA corresponding to the central network
  • the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • the ULCL since the ULCL only sends the received DNS request to the C-PSA corresponding to the central network, rather than to the corresponding C-PSAs of multiple networks (such as one or more local networks and central networks) PSA, that is, only one network request is made to resolve DNS requests at a time, so the number of DNS resolutions can be reduced, thereby reducing signaling overhead and improving resolution efficiency.
  • the C-DNS of the central network can resolve the IP address of the application server, the success rate of the DNS request resolution is improved, thereby further improving the DNS resolution efficiency.
  • the configuration information of the local network configured on the ULCL also includes the location information or service area information of the local network
  • the ULCL can Based on the location information or service area information of the local network, a local network closest to the UE is selected from multiple local networks.
  • the priority information is used by the ULCL to select a local network with the highest priority from at least one local network, then the first rule above.
  • the ULCL can select a local network from the multiple local networks based on the priority information of the local network.
  • the ULCL can also carry the location information of the terminal device in the DNS request, so that the C-DNS can resolve the DNS based on the location information of the terminal device.
  • Request the IP address obtained by parsing is closer to the terminal device.
  • the priorities among these first rules may be preset.
  • the above first rule may be configured based on UE granularity, that is, the first rule configured by different UEs may be the same or may be different.
  • the above first rule may be configured based on the granularity of each UPF, that is, the first rules configured by different UEs served by the same UPF are the same, but the first rules configured by different UEs served by different UPFs may be the same, Can also be different.
  • the following steps 409a to 409b are optional steps. If it is determined in the above step 408 that the service network for receiving the DNS request includes the local network 1, the following steps 409a and 409b are executed. If it is determined in the above step 408 that the service network part for receiving the DNS request includes the local network 1, the following steps 409a and 409b are not executed.
  • Step 409a the ULCL sends a DNS request to the L-PSA1 corresponding to the local network 1. Accordingly, L-PSA1 can receive the DNS request.
  • the L-PSA1 after receiving the DNS request, the L-PSA1 sends the DNS request to the L-DNS in the local network 1 for resolution.
  • the L-DNS in the local network 1 When the L-DNS in the local network 1 successfully resolves the DNS request, that is, the IP address of the application server corresponding to the application identifier in the DNS request is obtained, the L-DNS in the local network 1 sends the IP address to the L-PSA1, Then the L-PSA1 sends the IP address to the ULCL, and then the ULCL sends the IP address to the RAN, and the RAN sends the IP address to the UE.
  • the DNS request can be sent to the C-DNS for resolution, and then the C-DNS Send the resolution result (that is, the IP address of the application server) to the L-DNS of the local network 1, and then the L-DNS in the local network 1 sends the IP address to the L-PSA1, and the L-PSA1 sends the IP address to the ULCL, and then the ULCL
  • the IP address is sent to the RAN, and the RAN sends the IP address to the UE.
  • Step 409b the L-PSA1 sends response information to the ULCL. Accordingly, the ULCL can receive the response information.
  • the response information includes an IP address (which may be obtained by L-DNS resolution of local network 1 or obtained by C-DNS resolution), it indicates that L-PSA1 successfully resolves the DNS request.
  • the response information does not contain an IP address, it indicates that the L-PSA1 failed to resolve the DNS request.
  • the following steps 410a to 410b are optional steps. If it is determined in the above step 408 that the service network for receiving the DNS request includes the central network, the following steps 410a to 410b are executed. If it is determined in the above step 408 that the service network for receiving the DNS request does not include the central network, the following steps 410a to 410b are not executed.
  • Step 410a the ULCL sends a DNS request to the C-PSA corresponding to the central network. Accordingly, the C-PSA can receive the DNS request.
  • the C-PSA after receiving the DNS request, the C-PSA sends the DNS request to the C-DNS of the central network for resolution.
  • an application server corresponding to an application identifier is deployed in the central network, so the resolution can be successful.
  • the C-DNS stores a mapping relationship between an application identifier and the IP addresses of multiple application servers, where the multiple application servers include an application server located in the central network and an application server located in the local network.
  • the C-DNS After the C-DNS successfully resolves the application domain name, it sends the corresponding IP address to the C-PSA, the C-PSA sends the IP address to the ULCL, and the ULCL sends the IP address to the RAN, and the RAN sends the IP address to the UE.
  • Step 410b the C-PSA sends response information to the ULCL. Accordingly, the ULCL can receive the response information.
  • the response information includes an IP address, it indicates that the C-DNS successfully resolves the DNS request.
  • the DNS reply does not contain an IP address, it indicates that the C-DNS failed to resolve the DNS request.
  • Step 411 if the ULCL receives multiple IP addresses, it determines one IP address from them.
  • ULCL sends DNS requests to multiple UPFs (such as one or more L-PSAs, C-PSAs), it will receive a response message from each UPF, and some response messages carry IP addresses (that is, the resolution is successful). Some response information does not carry an IP address (that is, the resolution fails). If the ULCL receives multiple IP addresses, it selects one IP address (called the IP address of the first application server).
  • UPFs such as one or more L-PSAs, C-PSAs
  • the first application server may be an application server closest to the UE.
  • Step 412 the ULCL sends the IP address to the UE. Accordingly, the UE can receive the IP address.
  • the ULCL sends the IP address of the first application server to the UE.
  • the ULCL can select one or more service networks based on the configured first rule and the configuration information of the local network, and send the received DNS request to the PSAs corresponding to the selected one or more service networks. For example, when DNS requests are sent to multiple selected service networks, the resolution success rate of DNS requests can be improved. For another example, when a DNS request is sent to a local network where a DNS server is deployed, or to a local network where a DNS server capable of recursive resolution is deployed, the resolution success rate can also be improved. Therefore, the above solution can improve the success rate of DNS resolution. At the same time, an IP address of an application server closest to the terminal device can be obtained, which can reduce the delay and improve the user experience.
  • each network element in the above-mentioned implementation includes corresponding hardware structures and/or software modules for executing each function.
  • the present invention can be implemented in hardware or a combination of hardware and computer software in conjunction with the units and algorithm steps of each example described in the embodiments disclosed herein. Whether a function is performed by hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.
  • corresponding steps or operations implemented by access network equipment may also be implemented by components (such as chips or circuits) configured in access network equipment, and correspondingly implemented by user plane network elements.
  • the steps or operations may also be implemented by components (such as chips or circuits) configured on the user plane network element.
  • FIG. 5 it is a schematic diagram of a communication apparatus according to an embodiment of the present application.
  • the apparatus is used to implement various steps performed by the corresponding offload network element (ie, the ULCL) in the above-mentioned embodiment of FIG. 4 .
  • the corresponding offload network element ie, the ULCL
  • the receiving unit 510 is configured to receive a DNS request from a terminal device, where the DNS request includes an application identifier, and the DNS request is used to request the Internet Protocol IP address of the application server corresponding to the application identifier; Request corresponding response information, where the response information includes the IP address of the application server corresponding to the application identifier.
  • a processing unit 530 configured to determine at least one service network according to the first rule and configuration information of at least one local network, where the service network is deployed with a DNS server, and the configuration information of the local network includes capability information of the local network, The capability information of the local network is used to indicate whether the local network is deployed with a local DNS server, and the first rule is a determination rule of the service network.
  • the sending unit 520 is configured to send the DNS request to the protocol data unit anchor PSA corresponding to the at least one service network; send the IP address of the first application server to the terminal device, and all the data received by the offloading network element.
  • the IP address of the application server includes the IP address of the first application server.
  • the first rule is preconfigured on the offloading network element; or, the receiving unit 510 is further configured to receive the first rule from the session management network element.
  • the configuration information of the at least one local network is pre-configured on the offloading network element; or, the receiving unit 510 is further configured to receive the at least one local network element from the session management network element. Configuration information for a local network.
  • the first rule is based on the local DNS server deployment of the local network, the resolution capability of the local DNS server, the application server included in the local network, and the location of the local network. at least one of them is determined.
  • the first rule includes at least one of the following rules:
  • the capability information of the local network is further used to indicate whether the local DNS server supports recursive DNS resolution when the local network is deployed with a local DNS server;
  • the first rule also includes at least one of the following rules:
  • the capability information of the local network is further used to indicate information of application servers deployed in the local network;
  • the first rule further includes at least one of the following rules:
  • the configuration information of the local network further includes location information or service area information of the local network, where the location information or service area information is used to select one from the at least one local network The local network closest to the terminal device.
  • the IP address of the application server received by the receiving unit 510 includes multiple IP addresses
  • the first application server is an application server corresponding to the multiple IP addresses that satisfies the The terminal device distance is required by the application server.
  • the above-mentioned communication apparatus 500 may further include a storage unit, which is used to store data or instructions (also referred to as codes or programs), and each of the above-mentioned units may interact or be coupled with the storage unit to implement corresponding methods or Features.
  • the processing unit 530 may read data or instructions in the storage unit, so that the communication apparatus implements the methods in the above-mentioned embodiments.
  • each unit in the above apparatus can be realized in the form of software calling through the processing element; also can all be realized in the form of hardware; some units can also be realized in the form of software calling through the processing element, and some units can be realized in the form of hardware.
  • each unit can be a separately established processing element, or can be integrated in a certain chip of the device to be implemented, and can also be stored in the memory in the form of a program, which can be called by a certain processing element of the device and execute the unit's processing.
  • each step of the above method or each of the above units may be implemented by an integrated logic circuit of hardware in the processor element or implemented in the form of software being invoked by the processing element.
  • a unit in any of the above apparatuses may be one or more integrated circuits configured to implement the above method, such as: one or more Application Specific Integrated Circuits (ASICs), or, one or more Multiple microprocessors (digital singnal processors, DSP), or, one or more field programmable gate arrays (Field Programmable Gate Array, FPGA), or a combination of at least two of these integrated circuit forms.
  • ASICs Application Specific Integrated Circuits
  • DSP digital singnal processors
  • FPGA Field Programmable Gate Array
  • FPGA Field Programmable Gate Array
  • a unit in the apparatus 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 (Central Processing Unit, CPU) or other processors that can invoke programs.
  • CPU central processing unit
  • these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).
  • SOC system-on-a-chip
  • the above receiving unit 510 is an interface circuit of the device for receiving signals from other devices.
  • the receiving unit 510 is an interface circuit used by the chip to receive signals from other chips or devices.
  • the above sending unit 520 is an interface circuit of the device, and is used to send signals to other devices.
  • the sending unit 520 is an interface circuit used by the chip to send signals to other chips or devices.
  • FIG. 6 it is a schematic diagram of a communication apparatus according to an embodiment of the present application.
  • the apparatus is used to implement various steps performed by a corresponding session management network element (ie, SMF) in the embodiment of FIG. 4 .
  • the apparatus 600 includes a transceiver unit 610 and a processing unit 620 .
  • the processing unit 620 is configured to determine the first rule according to at least one of the local DNS server deployment of the local network, the resolution capability of the local DNS server, the application server included in the local network, and the location of the local network; determine; The local network that the terminal device can access.
  • the transceiver unit 610 is configured to send the configuration information of the local network that the terminal device can access and the first rule to the offloading network element, the configuration information of the local network includes the capability information of the local network, the local network The capability information of the network is used to indicate whether the local network is deployed with a local DNS server.
  • the above-mentioned communication device 600 may further include a storage unit, which is used to store data or instructions (also referred to as codes or programs), and each of the above-mentioned units may interact or be coupled with the storage unit to implement corresponding methods or Features.
  • the processing unit 620 may read data or instructions in the storage unit, so that the communication apparatus implements the methods in the above embodiments.
  • each unit in the device can all be implemented in the form of software calling through processing elements; also can all be implemented in hardware; some units can also be implemented in the form of software calling through processing elements, and some units can be implemented in hardware.
  • each unit can be a separately established processing element, or can be integrated in a certain chip of the device to be implemented, and can also be stored in the memory in the form of a program, which can be called by a certain processing element of the device and execute the unit's processing.
  • all or part of these units can be integrated together, and can also be implemented independently.
  • the processing element described here can also become a processor, which can 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 the processor element or implemented in the form of software being invoked by the processing element.
  • a unit in any of the above apparatuses may be one or more integrated circuits configured to implement the above methods, such as: one or more ASICs, or, one or more DSPs, or, one or more FPGA, or a combination of at least two of these integrated circuit forms.
  • the processing element can be a general-purpose processor, such as a CPU or other processors that can invoke programs.
  • these units can be integrated together and implemented in the form of SOC.
  • the above transceiver unit 610 is an interface circuit of the device, and is used to send signals to or receive signals from other devices.
  • the transceiver unit 610 is an interface circuit used by the chip to send signals to other chips or devices, or to receive signals from other chips or devices.
  • the communication apparatus includes: a processor 710 and an interface 730 , and optionally, the communication apparatus further includes a memory 720 .
  • the interface 730 is used to enable communication with other devices.
  • the method executed by the session management network element or the offloading network element in the above embodiment can be implemented by the processor 710 calling the program stored in the memory (which may be the memory 720 in the session management network element or the offloading network element, or an external memory).
  • the session management network element or the offload network element may include a processor 710, and the processor 710 executes the method performed by the session management network element or the offload network element in the above method embodiments by invoking the program in the memory.
  • the processor here may be an integrated circuit with signal processing capability, such as a CPU.
  • the session management network element or the offload network element may be implemented by one or more integrated circuits configured to implement the above methods. For example: one or more ASICs, or, one or more microprocessor DSPs, or, one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. Alternatively, the above implementations may be combined.
  • the functions/implementation process of the receiving unit 510, the sending unit 520 and the processing unit 530 in FIG. 5 can be implemented by the processor 710 in the communication apparatus 700 shown in FIG. 7 calling the computer-executable instructions stored in the memory 720 .
  • the function/implementation process of the processing unit 530 in FIG. 5 can be implemented by the processor 710 in the communication device 700 shown in FIG. 7 calling the computer execution instructions stored in the memory 720, and the receiving unit 510 in FIG.
  • the function/implementation process of the unit 520 can be implemented through the interface 730 in the communication device 700 shown in FIG. 7 .
  • the functions/implementation process of the transceiver unit 610 and the processing unit 620 in FIG. 6 can be implemented by the processor 710 in the communication apparatus 700 shown in FIG. 7 calling computer executable instructions stored in the memory 720 .
  • the function/implementation process of the processing unit 620 in FIG. 6 may be implemented by the processor 710 in the communication apparatus 700 shown in FIG. 7 calling the computer-executed instructions stored in the memory 720, and the function of the transceiver unit 610 in FIG. 6
  • the implementation process can be implemented through the interface 730 in the communication device 700 shown in FIG. 7 .
  • At least one item (single, species) of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.
  • “Plurality" means two or more, and other quantifiers are similar.
  • the above-mentioned embodiments it may be implemented in whole or in part by software, hardware, firmware or any combination thereof.
  • software it can be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated.
  • the computer may be a general purpose computer, special purpose computer, computer network, or other programmable device.
  • the computer instructions may be stored in or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server or data center Transmission to another website site, computer, server, or data center is by wire (eg, coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (eg, infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server, a data center, or the like that includes an integration of one or more available media.
  • the usable media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, DVDs), or semiconductor media (eg, solid state disks (SSDs)), and the like.
  • a general-purpose processor may be a microprocessor, or alternatively, the general-purpose processor may be any conventional processor, controller, microcontroller, or state machine.
  • a processor may also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a digital signal processor core, or any other similar configuration. accomplish.
  • the steps of the method or algorithm described in the embodiments of this application may be directly embedded in hardware, a software unit executed by a processor, or a combination of the two.
  • Software units can be stored in random access memory (Random Access Memory, RAM), flash memory, read-only memory (Read-Only Memory, ROM), EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM or this.
  • RAM Random Access Memory
  • ROM read-only memory
  • EPROM memory read-only memory
  • EEPROM memory electrically erasable programmable read-only memory
  • registers hard disk, removable disk, CD-ROM or this.
  • a storage medium may be coupled to the processor such that the processor may read information from, and store information in, the storage medium.
  • the storage medium can also be integrated into the processor.
  • the processor and storage medium may be provided in the ASIC.
  • the above-described functions described herein may be implemented in hardware, software, firmware, or any combination of the three. If implemented in software, the functions may be stored on, or transmitted over, a computer-readable medium in the form of one or more instructions or code.
  • Computer-readable media includes computer storage media and communication media that facilitate the transfer of a computer program from one place to another. Storage media can be any available media that a general-purpose or special-purpose computer can access.
  • Such computer-readable media may include, but are not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other device that can be used to carry or store instructions or data structures and Other media in the form of program code that can be read by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.
  • any connection is properly defined as a computer-readable medium, for example, if software is transmitted from a website site, server or other remote source over a coaxial cable, fiber optic computer, twisted pair, digital subscriber line (DSL) Or transmitted by wireless means such as infrared, wireless, and microwave are also included in the definition of computer-readable media.
  • DSL digital subscriber line
  • the discs and magnetic discs include compact discs, laser discs, optical discs, digital versatile discs (English: Digital Versatile Disc, DVD for short), floppy discs and Blu-ray discs. Disks usually reproduce data magnetically, while Discs usually use lasers to optically reproduce data. Combinations of the above can also be included in computer readable media.
  • the functions described in this application may be implemented in hardware, software, firmware, or any combination thereof.
  • the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium.
  • Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another.
  • a storage medium can be any available medium that can be accessed by a general purpose or special purpose computer.

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Abstract

本申请提供DNS请求的解析方法、通信装置及通信系统。方法包括：分流网元接收来自终端设备的DNS请求；分流网元根据第一规则和至少一个本地网络的配置信息确定至少一个服务网络；分流网元向至少一个服务网络对应的PSA发送DNS请求；分流网元接收与所述至少一个DNS请求对应的响应信息，响应信息包括应用服务器的IP地址；分流网元向终端设备发送第一应用服务器的IP地址，分流网元接收到的应用服务器的IP地址包括第一应用服务器的IP地址。该方案，分流网元可以基于第一规则和本地网络的配置信息，选择一个或多个服务网络，由于选择的服务网络部署有DNS服务器，可以避免无法解析的情形发生，提升了DNS请求的解析成功率。

Description

DNS请求的解析方法、通信装置及通信系统
相关申请的交叉引用
本申请要求在2020年07月03日提交中国专利局、申请号为202010637176.3、申请名称为“DNS请求的解析方法、通信装置及通信系统”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
本申请涉及通信技术领域，尤其涉及DNS请求的解析方法、通信装置及通信系统。
背景技术
当终端设备想要请求某个应用的服务时，如用户想要使用微信服务、或使用爱奇艺APP观看视频，则用户可以通过点击应用上的相应功能模块，从而触发终端设备与网络之间建立用户面会话，然后终端设备向网络发送域名系统(Domain Name System，DNS)请求，该请求中携带应用标识，分流网元在收到DNS请求后，将DNS请求发送给本地网络或中心网络的DNS服务器进行解析获取到应用服务器的互联网协议(internet protocol，IP)地址，然后分流网元将该IP地址发送给终端设备，终端设备可以根据该IP地址去访问相应的应用服务器，以获取应用服务器的数据内容，从而得到该应用的服务。
在解析DNS请求的过程中，如何提升DNS请求的解析成功率，是目前需要解决的。
发明内容
本申请提供DNS请求的解析方法、通信装置及通信系统，用以提升解析DNS请求的效率。
第一方面，本申请实施例提供一种DNS请求的解析方法，包括：分流网元接收来自终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；所述分流网元根据第一规则和至少一个本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器，所述第一规则为服务网络的确定规则；所述分流网元向所述至少一个服务网络对应的协议数据单元锚点PSA发送所述DNS请求；所述分流网元接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括所述应用标识对应的应用服务器的IP地址；所述分流网元向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用服务器的IP地址包括所述第一应用服务器的IP地址。
通过上述方案，分流网元可以基于配置的第一规则和本地网络的配置信息，选择一个或多个服务网络，并将接收到的DNS请求发送至选择的一个或多个服务网络对应的PSA，由于选择的服务网络内均部署有DNS服务器，因而可以避免发生无法解析的情形，从而可以提升DNS请求的解析成功率。
在一种可能的实现方法中，所述第一规则是预配置在所述分流网元上的；或者，所述 分流网元从会话管理网元接收所述第一规则。
在一种可能的实现方法中，所述至少一个本地网络的配置信息是预配置在所述分流网元上的；或者，所述分流网元从会话管理网元接收所述至少一个本地网络的配置信息。
在一种可能的实现方法中，所述第一规则是根据所述本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项确定的。
在一种可能的实现方法中，所述第一规则包括以下规则中的至少一种：
1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络。
3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；
所述第一规则还包括以下规则中的至少一种：
4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络；
7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；所述第一规则还包括以下规则中的至少一种：
10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
在一种可能的实现方法中，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于所述分流网元从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
基于该方案，可以得到一个距离终端设备最近的应用服务器的IP地址，可以减少时延，进而提升用户体验。
在一种可能的实现方法中，所述分流网元接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。比如，满足与所述终端设备距离要求的应用服务器可以是距离该终端设备最近的应用服务器、或与终端设备的距离小于预设阈值的应用服务器。
基于该方案，可以得到一个距离终端设备最近的应用服务器的IP地址，可以减少时延，进而提升用户体验。
第二方面，本申请实施例提供一种DNS请求的解析方法，包括：会话管理网元根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；所述会话管理网元确定终端设备能够接入的本地网络；所述会话管理网元向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。
第三方面，本申请实施例提供一种通信装置，该装置可以是分流网元，还可以是用于分流网元的芯片。该装置具有实现上述第一方面任意实现方法的功能。该功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与上述功能相对应的模块。
第四方面，本申请实施例提供一种通信装置，该装置可以是会话管理网元，还可以是用于会话管理网元的芯片。该装置具有实现上述第二方面的功能。该功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与上述功能相对应的模块。
第五方面，本申请实施例提供一种通信装置，包括处理器和存储器；该存储器用于存储计算机执行指令，当该装置运行时，该处理器执行该存储器存储的该计算机执行指令，以使该装置执行如上述第一方面至第二方面的任意实现方法。
第六方面，本申请实施例还提供一种芯片系统，包括：处理器，用于执行上述第一方面至第二方面的任意实现方法。
第七方面，本申请实施例提供一种通信装置，包括用于执行上述第一方面至第二方面的任意实现方法的各个步骤的单元或手段(means)。
第八方面，本申请实施例提供一种通信装置，包括处理器和接口电路，所述处理器用于通过接口电路与其它装置通信，并执行上述第一方面至第二方面的任意实现方法。该处理器包括一个或多个。
第九方面，本申请实施例提供一种通信装置，包括处理器，用于与存储器相连，用于调用所述存储器中存储的程序，以执行上述第一方面至第二方面的任意实现方法。该存储器可以位于该装置之内，也可以位于该装置之外。且该处理器包括一个或多个。
第十方面，本申请实施例还提供一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当其在计算机上运行时，使得处理器执行上述第一方面至第二方面的任意实现方法。
第十一方面，本申请实施例还提供一种计算机程序产品，该计算机产品包括计算机程序，当计算机程序运行时，使得上述第一方面至第二方面的任意实现方法被执行。
第十二方面，本申请实施例还提供一种通信系统，包括：会话管理网元，用于根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；确定终端设备能够接入的本地网络；向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。分流网元，用于从所述会话管理网元接收所述本地网络的配置信息和所述第一规则。
附图说明
图1为本申请实施例提供的一种通信系统示意图；
图2(a)为5G网络架构示意图；
图2(b)为5G网络架构又一示意图；
图3为多个PSA场景的一个示例图；
图4为本申请实施例提供的一种DNS请求的解析方法示意图；
图5为本申请实施例提供的一种通信装置示意图；
图6为本申请实施例提供的又一种通信装置示意图；
图7为本申请实施例提供的又一种通信装置示意图。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。方法实施例中的具体操作方法也可以应用于装置实施例或系统实施例中。其中，在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
为解决背景技术中提到的问题，如图1所示，本申请提供一种通信系统，该系统包括分流网元和会话管理网元。
会话管理网元，用于根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；确定终端设备能够接入的本地网络；向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。分流网元，用于从所述会话管理网元接收所述本地网络的配置信息和所述第一规则。
在一种可能的实现方法中，所述分流网元，还用于接收来自所述终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；根据所述第一规则和所述本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器；向所述至少一个服务网络对应的协议数据单 元锚点PSA发送所述DNS请求；接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括应用服务器的IP地址；向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用标识对应的应用服务器的IP地址包括所述第一应用服务器的IP地址。其中，所述服务网络部署有DNS服务器包括以下场景：DNS服务器可能部署在服务网络中，也可能部署在服务于该服务网络的UPF/PSA上，也可能部署在服务于该服务网络的UPF/PSA与服务网络之间的位置，DNS服务器的部署位置不做限定，所述服务网络可以为本地网络/边缘网络，也可以为中心网络。
在一种可能的实现方法中，所述第一规则包括以下规则中的至少一种：
1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络。
3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；所述第一规则还包括以下规则中的至少一种：
4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络；
7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；所述第一规则还包括以下规则中的至少一种：
10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS 请求发送给中心网络；
13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
在一种可能的实现方法中，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于所述分流网元从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
在一种可能的实现方法中，所述分流网元接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。
在一种可能的实现方法中，所述本地网络的配置信息还包括所述本地网络的优先级信息，所述优先级信息用于所述分流网元从所述至少一个本地网络中选择一个优先级最高的本地网络。
其中，上述方案的具体实现将在后续方法实施例部分详细阐述，在此不再赘述。
图1所示的系统可以用在图2(a)或图2(b)所示的第五代(5th generation，5G)网络架构中，当然，也可以用在未来网络架构，比如第六代(6th generation，6G)网络架构等，本申请不做限定。
示例性的，假设图1所示的通信系统应用于5G网络架构，如图2(a)所示，为5G网络架构示意图。图1中的会话管理网元所对应的网元或者实体可以为图2(a)所示的5G网络架构中的会话管理功能(session management function，SMF)网元，图1中的分流网元所对应的网元或者实体可以为图2(a)所示的5G网络架构中的用户面功能(user plane function，UPF)网元。
示例性的，假设图1所示的通信系统应用于5G网络架构，如图2(b)所示，为5G网络架构示意图。图1中的会话管理网元所对应的网元或者实体可以为图2(a)所示的5G网络架构中的SMF网元，图1中的分流网元所对应的网元或者实体可以为图2(a)所示的5G网络架构中的上行分流(Uplink classifier，ULCL)网元。
图2(a)所示的5G网络架构中可包括三部分，分别是终端设备部分、数据网络(data network，DN)和运营商网络部分。下面对其中的部分网元的功能进行简单介绍说明。
其中，运营商网络可包括以下网元中的一个或多个：鉴权服务器功能(Authentication Server Function，AUSF)网元、网络开放功能(network exposure function，NEF)网元、策略控制功能(Policy Control Function，PCF)网元、统一数据管理(unified data management，UDM)、统一数据库(Unified Data Repository，UDR)、应用功能(Application Function，AF)网元、接入与移动性管理功能(Access and Mobility Management Function，AMF)网元、SMF网元、无线接入网(radio access network，RAN)设备以及UPF网元等。上述运营商网络中，除无线接入网部分之外的部分可以称为核心网络部分。
在具体实现中，本申请实施例中的终端设备，可以是用于实现无线通信功能的设备。其中，终端设备可以是5G网络或者未来演进的公共陆地移动网络(public land mobile network，PLMN)中的用户设备(user equipment，UE)、接入终端、终端单元、终端站、 移动站、移动台、远方站、远程终端、移动设备、无线通信设备、终端代理或终端装置等。接入终端可以是蜂窝电话、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、个人数字助理(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、车载设备或可穿戴设备，虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等。终端可以是移动的，也可以是固定的。
上述终端设备可通过运营商网络提供的接口(例如N1等)与运营商网络建立连接，使用运营商网络提供的数据和/或语音等服务。终端设备还可通过运营商网络访问DN，使用DN上部署的运营商业务，和/或第三方提供的业务。其中，上述第三方可为运营商网络和终端设备之外的服务方，可为终端设备提供其他数据和/或语音等服务。其中，上述第三方的具体表现形式，具体可根据实际应用场景确定，在此不做限制。
RAN是运营商网络的子网络，是运营商网络中业务节点与终端设备之间的实施系统。终端设备要接入运营商网络，首先是经过RAN，进而可通过RAN与运营商网络的业务节点连接。本申请中的RAN设备，是一种为终端设备提供无线通信功能的设备，RAN设备也称为接入网设备。本申请中的RAN设备包括但不限于：5G中的下一代基站(g nodeB，gNB)、演进型节点B(evolved node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved nodeB，或home node B，HNB)、基带单元(baseBand unit，BBU)、传输点(transmitting and receiving point，TRP)、发射点(transmitting point，TP)、移动交换中心等。
AMF网元，主要进行移动性管理、接入鉴权/授权等功能。此外，还负责在UE与PCF间传递用户策略。
SMF网元，主要进行会话管理、PCF下发控制策略的执行、UPF的选择、UE IP地址分配等功能。
UPF网元，作为和数据网络的接口UPF，完成用户面数据转发、基于会话/流级的计费统计，带宽限制等功能。
UDM网元，主要负责管理签约数据、用户接入授权等功能。
UDR，主要负责签约数据、策略数据、应用数据等类型数据的存取功能。
NEF网元，主要用于支持能力和事件的开放。
AF网元，主要传递应用侧对网络侧的需求，例如，服务质量(Quality of Service，QoS)需求或用户状态事件订阅等。AF可以是第三方功能实体，也可以是运营商部署的应用服务，如IP多媒体子系统(IP Multimedia Subsystem，IMS)语音呼叫业务。
PCF网元，主要负责针对会话、业务流级别进行计费、QoS带宽保障及移动性管理、UE策略决策等策略控制功能。
AUSF网元：主要负责对用户进行鉴权，以确定是否允许用户或设备接入网络。
DN，是位于运营商网络之外的网络，运营商网络可以接入多个DN，DN上可部署多种业务，可为终端设备提供数据和/或语音等服务。例如，DN是某智能工厂的私有网络， 智能工厂安装在车间的传感器可为终端设备，DN中部署了传感器的控制服务器，控制服务器可为传感器提供服务。传感器可与控制服务器通信，获取控制服务器的指令，根据指令将采集的传感器数据传送给控制服务器等。又例如，DN是某公司的内部办公网络，该公司员工的手机或者电脑可为终端设备，员工的手机或者电脑可以访问公司内部办公网络上的信息、数据资源等。
在图2(a)所示的架构中，各个网元之间的接口名称及功能如下：
1)、N7：PCF与SMF之间的接口，用于下发协议数据单元(protocol data unit，PDU)会话粒度以及业务数据流粒度控制策略。
2)、N15：PCF与AMF之间的接口，用于下发UE策略及接入控制相关策略。
3)、N5：AF与PCF之间的接口，用于应用业务请求下发以及网络事件上报。
4)、N4：SMF与UPF之间的接口，用于控制面与用户面之间传递信息，包括控制面向用户面的转发规则、QoS控制规则、流量统计规则等的下发以及用户面的信息上报。
5)、N11：SMF与AMF之间的接口，用于传递RAN和UPF之间的PDU会话隧道信息、传递发送给UE的控制消息、传递发送给RAN的无线资源控制信息等。
6)、N2：AMF与RAN之间的接口，用于传递核心网侧至RAN的无线承载控制信息等。
7)、N1：AMF与终端设备之间的接口，用于向UE传递QoS控制规则等。
8)、N8：AMF与UDM间的接口，用于AMF向UDM获取接入与移动性管理相关签约数据与鉴权数据，以及AMF向UDM注册UE当前移动性管理相关信息等。
9)、N10：SMF与UDM间的接口，用于SMF向UDM获取会话管理相关签约数据，以及SMF向UDM注册UE当前会话相关信息等。
10)、N35：UDM与UDR间的接口，用于UDM从UDR中获取用户签约数据信息。
11)、N36：PCF与UDR间的接口，用于PCF从UDR中获取策略相关签约数据以及应用数据相关信息。
12)、N12：AMF和AUSF间的接口，用于AMF向AUSF发起鉴权流程，其中可携带SUCI作为签约标识；
13)、N13：UDM与AUSF间的接口，用于AUSF向UDM获取用户鉴权向量，以执行鉴权流程。
可以理解的是，上述网元或者功能既可以是硬件设备中的网络元件，也可以是在专用硬件上运行软件功能，或者是平台(例如，云平台)上实例化的虚拟化功能。可选的，上述网元或者功能可以由一个设备实现，也可以由多个设备共同实现，还可以是一个设备内的一个功能模块，本申请实施例对此不作具体限定。
本申请中的会话管理网元、用户面网元分别可以是图2(a)或图2(b)中的SMF、UPF(如ULCL、PSA1、PSA2)，也可以是未来通信如6G网络中具有上述SMF、UPF的功能的网元，本申请对此不限定。为方便说明，本申请以会话管理网元、用户面网元分别为上述SMF、UPF为例进行说明。
以上图2(a)所示的5G网络架构中只有一个UPF，在上述架构的基础上，5G还支持在一个PDU会话的用户面路径上插入一个或多个协议数据单元锚点(PDU Session Anchor，PSA)UPF，以支持到本地网络(或称为边缘数据网络、或称为移动边缘计算(Mobile Edge  Compute，MEC)网络、或称为本地数据网络、或称为MEC)的连接，从而使得终端设备可以就近访问本地数据网络中的应用。其中，每个PSA是一个UPF。
在图2(a)的基础上，可以引入多个UPF，得到如图2(b)所示的5G网络架构。其中，图2(a)中的部分网元在图2(b)中没有示出。引入的多个UPF包括：ULCL UPF、PSA UPF1和PSA UPF-2。需要说明的是，图2(b)仅作为示例，实际应用中，对于PSA的数量没有限定，可以是一个、两个或两个以上。
本申请实施例中，分流网元可以为ULCL UPF，ULCL UPF也可以称为ULCL、分流点(Branching Point，BP)、BP UPF等，以下均用ULCL表示。
本申请实施例中，PSA UPF也可以称为UPF PSA或PSA等，以下用PSA表示。因此上述PSA UPF1、PSA UPF2也可以称为PSA1、PSA2。
ULCL用于根据分发规则，将从终端设备接收到的上行数据包分发给PSA1或PSA2，并将从PSA1或PSA2接收到的下行数据包发送给终端设备。
PSA1与DN间存在N6接口，例如该DN可以是位于中心数据中心(Data Center，DC)的DN，此时该PSA1也可以称为中心PSA(center PSA，C-PSA)或远端PSA。PSA2与本地DN间存在N6接口，例如该本地DN可以是位于本地DC(即MEC网络)中的DN，此时该PSA2也可以称为本地PSA(local PSA，L-PSA)。
当终端设备所处的位置存在接入到本地DN的UPF(如上述PSA2)时，SMF可将该UPF作为L-PSA插入到会话路径中，以便终端设备可以就近访问本地DN中的应用。上述图2(b)仅示出了一个L-PSA(即PSA2)，实际应用中也可以包括多个L-PSA。
如图3所示，为多个PSA场景的一个示例图。其中，ULCL可连接多个L-PSA，图中以连接两个L-PSA(即L-PSA1和L-PSA2)为例。该示例中，L-PSA1连接本地网络1，L-PSA2连接本地网络2，C-PSA连接中心网络(也称为中心数据网络、中心DC、远端网络、远端数据网络等)。并且，本地网络1中部署了DNS服务器，本地网络2中没有部署DNS服务器，中心网络中部署了DNS服务器。其中，本地网络中部署的DNS服务器也可以称为边缘DNS服务器或本地(Local)DNS服务器，以下用L-DNS表示本地网络中的本地DNS服务器，中心网络中部署的DNS服务器也可以称为中心(center)DNS服务器，以下用C-DNS表示中心网络中的中心DNS服务器。
在现网中，L-DNS可以与为本地网络提供服务的UPF合一部署，比如，图3的示例中，本地网络1可以与L-PSA1合一部署，本地网络2可以与L-PSA2合一部署，并且ULCL可以与某个L-PSA合一部署，比如ULCL与L-PSA1合一部署。
本地网络中部署的L-DNS可用于解析本地网络中的应用服务器对应的DNS请求。本地网络中部署的L-DNS可能与中心网络中部署的C-DNS服务器之间有连接(即可以互通)，也可能与中心网络中部署的C-DNS之间没有连接(即不能互通)。
当终端设备想要请求某个应用的服务时，如用户想要使用微信服务、或使用爱奇艺APP观看视频，则用户可以通过点击应用上的相应功能模块，从而触发终端设备与网络之间建立用户面会话，然后终端设备向网络发送DNS请求，该请求中携带应用标识(如完全限定域名(Fully Qualified Domain Name，FQDN))，ULCL在收到DNS请求后，将DNS请求发送给某个PSA，比如发送给L-PSA1，然后L-PSA1将DNS请求发送给本地网络1中的L-DNS，该L-DNS查询该应用标识对应的IP地址，并将IP地址发送给L-PSA1，L-PSA1将IP地址发送给ULCL，ULCL再将IP地址通过RAN发送给终端设备，从而终端设备可 以根据该IP地址去访问相应的应用服务器，以获取应用服务器的数据内容，从而得到该应用的服务。
其中，这里的IP地址是应用标识对应的应用服务器的IP地址，具体可以是该应用服务器在中心网络中的IP地址和/或在一个或多个本地网络中的IP地址。比如该应用是微信，则获取的IP地址是微信应用服务器的IP地址。一般地，当本地网络或中心网络部署了DNS服务器和应用服务器，则该DNS服务器内存储有应用服务器的应用标识与IP地址之间的映射关系。以图3的本地网络1为例，若本地网络1内部署有微信应用服务器、爱奇艺应用服务器、腾讯应用服务器，则本地网络1的DNS服务器内存储有微信域名与微信应用服务器的IP地址之间的映射关系、爱奇艺域名与爱奇艺应用服务器的IP地址之间的映射关系及腾讯域名与腾讯应用服务器的IP地址之间的映射关系。
一般地，对于同一应用的应用服务器，可以部署在中心网络，同时为了能够实现为用户提供就近服务，以提升用户体验，也可以在中心网络部署应用服务器的同时，还将该应用的服务器部署在一个或多个本地网络中。以图3为例，既可以在中心网络部署腾讯应用服务器，同时还可以在本地网络1和/或本地网络2部署腾讯应用服务器。
下面对实际DNS请求过程中可能存在的情形及可能出现的一些问题进行说明。
当ULCL接收到DNS请求(其中携带应用标识)后，需要将DNS请求发送给某个PSA，则存在以下几种情形：
情形1、PSA对应的本地网络中没有部署DNS服务器
参考图3，比如ULCL将DNS请求发送给L-PSA2，但L-PSA2对应的本地网络没有部署DNS服务器，因此L-PSA2无法将DNS请求发送给相应的DNS服务器，导致该DNS请求无法被解析。
情形2、PSA对应的本地网络中部署了DNS服务器
当PSA对应的本地网络中部署了DNS服务器，则本地网络中的DNS服务器可以解析DNS请求。根据本地网络中是否部署有DNS请求中的应用标识对应的应用服务器，该情形2又可以分为以下情形2.1和情形2.2。
情形2.1、PSA对应的本地网络中部署有DNS请求中的应用标识对应的应用服务器
参考图3，比如ULCL将DNS请求发送给L-PSA1，L-PSA1对应的本地网络部署了DNS服务器，因此L-PSA1可以将DNS请求发送给本地网络1中的DNS服务器，DNS服务器可以对该DNS请求进行解析。
当本地网络1中部署有DNS请求中的应用标识对应的应用服务器，则本地网络1的DNS服务器中存储有该应用标识与该应用服务器的IP地址之间的对应关系，因此DNS服务器可以成功解析获得应用服务器的IP地址。
情形2.2、PSA对应的本地网络中没有部署DNS请求中的应用标识对应的应用服务器
参考图3，比如ULCL将DNS请求发送给L-PSA1，L-PSA1对应的本地网络1部署了DNS服务器，因此L-PSA1可以将DNS请求发送给本地网络1中的DNS服务器，DNS服务器可以对该DNS请求进行解析。
当本地网络1中没有部署DNS请求中的应用标识对应的应用服务器，则本地网络1的DNS服务器中可能没有存储该应用标识与该应用服务器的IP地址之间的对应关系，因此DNS服务器无法成功解析获得应用服务器的IP地址。
针对该情形2.2，进一步还可以根据本地网络中的DNS服务器与中心网络中的DNS 服务器之间是否有连接(即互通)，将该情形2.2划分为以下情形2.2.1和情形2.2.2。
情形2.2.1、本地网络中部署的DNS服务器与中心网络中部署的DNS服务器之间有连接
当MEC中部署的DNS服务器与中心网络中部署的DNS服务器之间有连接，则本地网络中的DNS服务器对DNS请求中的应用标识解析失败时，可以将DNS请求发送给中心网络中的DNS服务器，由中心网络中的DNS服务器对DNS请求中的应用标识进行解析。也即，该情形下，本地网络中的DNS服务器支持递归解析。其中，中心网络中部署的DNS服务器并不特指图3中的C-DNS，而是泛指具有DNS解析能力、且与该本地网络中的DNS服务器有接口的DNS服务器，即本地网络中的DNS服务器将DNS请求发送至该DNS服务器后，该DNS服务器能解析所述DNS请求。
一般地，中心网络中的DNS服务器部署有应用标识对应的应用服务器，因而可以解析成功。并且中心网络中的DNS服务器上存储有一个应用标识与多个应用服务器的IP地址之间的映射关系，这里的多个应用服务器包括位于中心网络的应用服务器和位于本地网络中的应用服务器。
中心网络中的DNS服务器解析对应用域名解析成功后，将相应的IP地址发送给本地网络中部署的DNS服务器，然后由本地网络对应的L-PSA发送给ULCL，进一步的发送给终端设备。
需要说明的是，通过这种递归方式，中心网络中的DNS服务器解析得到的IP地址可能不是最优的IP地址，也即该IP地址对应的应用服务器可能不是距离终端设备最近或较近的应用服务器，因而可能会导致用户体验不佳。在一种实现方法中，本地网络中的DNS服务器对DNS请求中的应用标识解析失败时，可以将DNS请求发送给中心网络中的DNS服务器，并且，在DNS请求中还携带终端设备的位置信息，这样，中心网络的DNS服务器就能基于终端设备的位置信息解析DNS请求，解析得到的IP地址距离终端设备较近。
情形2.2.2、本地网络中部署的DNS服务器与中心网络中部署的DNS服务器之间没有连接
该情形中，本地网络中部署的DNS服务器无法解析DNS请求，并且也无法请求中心网络中部署的DNS服务器解析该DNS请求，则解析失败。
以上是ULCL将DNS请求发送给不同的PSA时可能会出现的各种情形，原则上，如果本地网络中的DNS服务器能解析，则应该由本地网络的DNS服务器去解析，这是因为本地网络的DNS服务器可以获得一个距离终端设备最近的应用服务器的IP地址，而如果由中心网络的DNS服务器解析，一方面由于路径较远，造成时延，另一方面中心网络的DNS服务器解析得到的IP地址对应的应用服务器可能不是距离终端设备最近的应用服务器，造成用户体验不佳。
从以上分析的各种情形可以看出，一方面，ULCL将接收到的DNS请求发送给相应的PSA时，可能最终无法解析该DNS请求(如上述情形1、情形2.2.2)，从而ULCL需要重新选择一个PSA并将DNS请求发送给该PSA，造成信令浪费，另一方面，如果ULCL一开始将DNS请求发送给中心PSA，则中心DNS服务器解析得到的IP地址对应的应用服务器可能不是距离终端设备最近的应用服务器，造成用户体验不佳。
因此，如何提升DNS请求的解析效率(如提升解析成功率、减少DNS请求的次数等)，是本申请要解决的。
为解决上述提到的问题，基于图2(b)或图3所示的网络架构，如图4所示，本申请提供一种DNS请求的解析方法。该实施例中，以终端设备为UE为例进行说明。该实施例是结合图3所示的网络架构进行说明的。实际应用中，本申请实施例不限于图3所示的网络架构。本申请实施例可以适用于部署有一个本地网络、两个本地网络或两个以上的本地网络的情形。
该方法包括以下步骤：
步骤401，SMF配置第一规则和本地网络的配置信息。
这里的本地网络可以是一个或多个本地网络。本地网络也可以称为边缘网络、MEC网络、MEC、本地数据网络等。
其中，第一规则(也可以称为DNS请求转发规则、转发规则、确定规则等)可以是由管理员通过网管系统配置在SMF上的，或者也可以是SMF确定的。比如，SMF根据本地网络的L-DNS部署、L-DNS的解析能力、本地网络所包含的应用服务器和本地网络的位置中的至少一项，确定第一规则。
其中，本地网络的配置信息可以是管理员通过网管系统配置在SMF上的，或者也可以是SMF确定的。其中，本地网络的配置信息至少包含本地网络的能力信息，本地网络的能力信息用于指示本地网络是否部署有L-DNS。
可选的，本地网络的能力信息还用于指示当本地网络部署有L-DNS时，L-DNS是否支持递归DNS解析。其中，当L-DNS与C-DNS之间有接口时，则L-DNS支持递归解析。
可选的，本地网络的能力信息还用于指示本地网络部署的应用服务器的信息。
可选的，本地网络的配置信息还包括本地网络的位置信息或服务区域信息。本地网络的位置信息或服务区域信息可以用跟踪区域标识(Tracking Area Indicator，TAI)来表示，用于指示本地网络所在的位置。
步骤402，UE创建PDU会话。
此时，SMF还没有在该PDU会话中插入ULCL，且PDU会话的当前用户面路径为：UE<->RAN<->C-PSA。
步骤403，SMF插入ULCL。
SMF可以是在UE创建会话过程中插入ULCL，也可以在UE创建会话之后动态插入。
触发SMF插入ULCL的触发事件可以是：SMF检测到UE移动、SMF收到来自C-PSA的DNS请求、或接收来自PCF的通知等。
步骤404，SMF向ULCL发送第一规则和本地网络的配置信息。相应地，ULCL可以接收到第一规则和本地网络的配置信息。
SMF创建SMF与ULCL之间的N4会话，然后通过N4会话向ULCL发送第一规则和本地网络的配置信息，ULCL可以根据该第一规则和本地网络的配置信息确定将接收到的DNS请求发送至相应的UPF，这里的UPF可以是L-PSA和/或C-PSA。
需要说明的是，如果UE的当前位置有多个本地网络可以接入，也即UE所在的位置处于多个本地网络的覆盖范围，则SMF向ULCL发送第一规则和多个本地网络的配置信息。
作为一种实现方法，SMF可以确定创建PDU会话的UE能够接入的本地网络，然后向ULCL发送第一规则和UE能够接入的本地网络的配置信息。
步骤405，ULCL配置第一规则和本地网络的配置信息。
ULCL接收到第一规则和本地网络的配置信息后，将第一规则和本地网络的配置信息配置在ULCL上。
在ULCL上配置第一规则和本地网络的配置信息后，ULCL可以基于第一规则和本地网络的配置信息，来判断将接收到的DNS请求转发至哪个UPF。
需要说明的是，作为另一种实现方法，ULCL上的第一规则也可以是预配置在ULCL上的，例如可以是由管理员通过网管系统进行预配置的。当ULCL上的第一规则是预配置在ULCL上的，则不需要通过SMF向ULCL配置第一规则。
作为另一种实现方法，ULCL上的本地网络的配置信息也可以是预配置在ULCL上的，例如可以是由管理员通过网管系统进行预配置的。当ULCL上的本地网络的配置信息是预配置在ULCL上的，则不需要通过SMF向ULCL配置本地网络的配置信息。
步骤406a，SMF插入L-PSA1，创建ULCL与L-PSA1之间的隧道。
如图4所示，为了可以建立与本地网络1之间的用户面连接，可以将L-PSA1插入到UE的PDU会话的用户面路径，并创建ULCL与L-PSA1之间的隧道，从而建立了用户面路径：UE<->RAN<->L-PSA1<->本地网络1。
步骤406b，SMF插入L-PSA2，创建ULCL与L-PSA2之间的隧道。
如图4所示，为了可以建立与本地网络2之间的用户面连接，可以将L-PSA2插入到UE的PDU会话的用户面路径，并创建ULCL与L-PSA2之间的隧道，从而建立了用户面路径：UE<->RAN<->L-PSA2<->本地网络2。
步骤407，ULCL接收到DNS请求。
该DNS请求由UE发送至RAN，RAN将DNS请求发送至ULCL。
该DNS请求包括应用标识，DNS请求用于请求查询该应用标识对应的应用服务器的IP地址。
步骤408，ULCL确定用于接收DNS请求的至少一个服务网络。
这里的服务网络可以是本地网络或中心网络。该服务网络部署有DNS服务器。
比如，当服务网络是本地网络，则部署有L-DNS。可选的，本地网络中还可以部署有一个或多个应用服务器(即本地应用服务器)。其中，一个本地网络对应一个或多个L-PSA，或者称为该一个或多个L-PSA为本地网络提供服务，L-PSA与本地网络可以合一部署，也可以分开部署。可选的，L-DNS与中心网络的C-DNS之间存在接口，则该L-DNS支持递归解析，也即可以将接收到的DNS请求转发至L-DNS进行解析。
当服务网络是中心网络，则部署有C-DNS。可选的，中心网络中还可以部署有一个或多个应用服务器(即中心应用服务器)。其中，一个中心网络对应一个或多个C-PSA，或者称为该一个或多个C-PSA为中心网络提供服务，C-PSA与中心网络可以合一部署，也可以分开部署。可选的，C-DNS与一个或多个本地网络的L-DNS之间存在接口，则该C-DNS可以接收该一个或本地网络发送的DNS请求，并在对DNS请求解析后，将解析得到的IP地址发送至本地网络的L-DNS。
该步骤408中，由ULCL确定需要由哪个或哪些网络内的DNS服务器来解析该DNS请求。
作为一种实现方法，ULCL可以基于第一规则和至少一个本地网络的配置信息，确定至少一个服务网络，进而可以确定至少一个服务网络分别对应的PSA(如L-PSA和/或 C-PSA)。
作为示例，当ULCL上配置的本地网络的配置信息中的本地网络的能力信息用于指示本地网络是否部署有L-DNS，则ULCL上配置的第一规则包括但不限于以下至少一种：
第一规则1、若UE可接入的本地网络都没有部署L-DNS，则将DNS请求发送给中心网络。
也即，若UE可接入的本地网络都没有部署L-DNS，则将DNS请求发送给中心网络对应的C-PSA，该C-PSA将DNS请求发送给中心网络的C-DNS进行解析。
基于该第一规则，不将DNS请求发送给没有部署L-DNS的本地网络对应的L-PSA，而是直接发给中心网络对应的C-PSA，可以提升DNS请求的解析成功率，进而提升解析效率。
第一规则2、将DNS请求发送给UE可接入的本地网络中部署有L-DNS的本地网络，以及发送给中心网络。可选的，可以预定义该多个本地网络以及中心网络之间的优先级，从而当ULCL从多个网络接收到IP地址时，可以根据该优先级，从接收到的多个IP地址选择一个。
基于该第一规则，由于ULCL将接收到的DNS请求发送给多个本地网络以及发送给中心网络，而不是仅发送给一个本地网络或仅发送给中心网络，也即每次向多个服务网络请求解析DNS请求，因此可提升DNS请求的解析成功率，进而提升解析效率。
第一规则3、将DNS请求发送给UE可接入的本地网络中一个或多个部署有L-DNS的本地网络。可选的，可以预定义该多个本地网络之间的优先级，从而当ULCL从多个网络接收到IP地址时，可以根据该优先级，从接收到的多个IP地址选择一个。
基于该第一规则，由于ULCL将接收到的DNS请求发送给多个本地网络以及发送给中心网络，而不是仅发送给一个本地网络，也即每次向多个服务网络请求解析DNS请求，因此可提升DNS请求的解析成功率，进而提升解析效率。
作为示例，当ULCL上配置的本地网络的配置信息中的本地网络的能力信息还用于指示当本地网络部署有L-DNS时，L-DNS是否支持递归DNS解析，则ULCL上配置的第一规则进一步可以包括但不限于以下至少一种：
第一规则4、若UE可接入的本地网络中存在多个本地网络部署有支持递归DNS解析的L-DNS，则从中选择一个本地网络，将DNS请求发送给被选择的本地网络。
也即，将DNS请求发送给被选择的本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该本地网络中的L-DNS进行解析。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于是将DNS请求发送给部署有支持递归DNS解析的L-DNS的本地网络对应的L-PSA，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
第一规则5、若UE可接入的本地网络中仅存在一个本地网络部署有支持递归DNS解析的L-DNS，则将DNS请求发送给本地网络。
也即，ULCL将DNS请求发送给该本地网络对应的L-PSA，由该L-PSA将DNS请求 发送给该本地网络中的L-DNS进行解析。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于是将DNS请求发送给部署有支持递归DNS解析的L-DNS的本地网络对应的L-PSA，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
第一规则6、若UE可接入的本地网络中存在多个本地网络部署有支持递归DNS解析的L-DNS，则将DNS请求发送给该多个本地网络。可选的，可以预先定义该多个本地网络之间的优先级，从而当ULCL从多个本地网络接收到IP地址，则可以根据该优先级，从接收到的多个IP地址选择一个。
也即，ULCL可以将DNS请求发送给该多个本地网络分别对应的L-PSA，由这些L-PSA将DNS请求分别发送给相应的本地网络中的L-DNS进行解析。
基于该第一规则，一方面，由于ULCL将接收到的DNS请求发送给多个本地网络分别对应的L-PSA，而不是仅发送给一个本地网络对应的L-PSA，也即每次向多个本地网络请求解析DNS请求，因此可提升DNS解析的成功率，进而提升解析效率。另一方面，由于是将DNS请求发送给部署有支持递归DNS解析的L-DNS的本地网络对应的L-PSA，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
第一规则7、若UE可接入的本地网络中存在多个本地网络部署有不支持递归DNS解析的L-DNS，则从中选择一个本地网络，将DNS请求发送给被选择的本地网络。
也即，ULCL将DNS请求发送给该被选择的一个本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该本地网络中的L-DNS进行解析。若解析失败，则可以从上述多个本地网络中选择一个其他本地网络，将DNS请求发送给该其他本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该其他本地网络中的L-DNS进行解析。以此类推，直至解析成功，或者全部解析失败，则将DNS请求发送给中心网络对应的C-PSA，该C-PSA将DNS请求发送给中心网络的C-DNS进行解析。
基于该第一规则，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA或中心网络对应的C-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。
第一规则8、若UE可接入的本地网络中仅存在一个本地网络部署有不支持递归DNS解析的L-DNS，则将DNS请求发送给本地网络。
也即，ULCL将DNS请求发送给该本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该本地网络中的L-DNS进行解析。若解析失败，则将DNS请求发送给中心网络对应的C-PSA，该C-PSA将DNS请求发送给中心网络的C-DNS进行解析。
基于该第一规则，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA或中心网络对应的C-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。
第一规则9、若UE可接入的本地网络中存在多个本地网络部署有不支持递归DNS解析的L-DNS，则将DNS请求发送给该多个本地网络。可选的，可以预先定义该多个本地 网络之间的优先级，从而ULCL在接收到多个IP地址时，可以根据该优先级，从接收到的多个IP地址选择一个。
也即ULCL将DNS请求发送给该多个本地网络分别对应的L-PSA，由这些L-PSA将DNS请求分别发送给相应的本地网络中的L-DNS进行解析。若上述多个本地网络对应的L-DNS均解析失败，则将DNS请求发送给中心网络对应的C-PSA，该C-PSA将DNS请求发送给中心网络的C-DNS进行解析。
基于该第一规则，由于ULCL将接收到的DNS请求发送给多个本地网络分别对应的L-PSA，而不是仅发送给一个本地网络对应的L-PSA，也即每次向多个本地网络请求解析DNS请求，因此可提升DNS解析的成功率，进而提升解析效率。
作为示例，当ULCL上配置的本地网络的配置信息中的本地网络的能力信息还用于指示本地网络部署的应用服务器的信息，本地网络部署的应用服务器的信息用于指示本地网络中部署了哪些应用服务器，比如可以用应用标识(如FQDN来表示)来指示部署的应用服务器。则ULCL上配置的第一规则进一步可以包括但不限于以下至少一种：
第一规则10、若UE可接入的本地网络中存在多个本地网络部署有应用标识对应的应用服务器、且多个本地网络部署有L-DNS，则从该多个本地网络中选择一个本地网络，将DNS请求发送给被选择的本地网络。
也即，ULCL将DNS请求发送给被选择的本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该本地网络中的L-DNS进行解析。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于该本地网络部署有DNS请求中的应用标识对应的应用服务器，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
第一规则11、若UE可接入的本地网络中仅存在一个本地网络部署有应用标识对应的应用服务器、且本地网络部署有L-DNS，则将DNS请求发送给本地网络。
也即，ULCL将DNS请求发送给该本地网络对应的L-PSA，由该L-PSA将DNS请求发送给该本地网络中的L-DNS进行解析。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给一个本地网络对应的L-PSA，而不是发送给多个本地网络分别对应的L-PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于该本地网络部署有DNS请求中的应用标识对应的应用服务器，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
第一规则12、若UE可接入的本地网络中存在一个或多个本地网络部署有应用标识对应的应用服务器、且该一个或多个本地网络都没有部署L-DNS，则将DNS请求发送给中心网络。
也即，ULCL将DNS请求发送给中心网络对应的C-PSA，由该C-PSA将DNS请求发送给该中心网络中的C-DNS进行解析。可选的，还将该一个或多个本地网络的位置信息或服务区域信息发送给C-DNS，从而C-DNS可以根据该一个或多个本地网络的位置信息或服务区域信息，选择一个距离UE最近的应用服务器。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给中心网络对应的C-PSA，而不是发送给多个网络分别对应的PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于该中心网络部署有DNS请求中的应用标识对应的应用服务器，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。另一方面，不将DNS请求发送给没有部署L-DNS的本地网络，可以减少不必要的信令开销。
第一规则13、若UE可接入的本地网络都没有部署应用标识对应的应用服务器，则将DNS请求发送给中心网络。
也即，ULCL将DNS请求发送给中心网络对应的C-PSA，由C-PSA将DNS请求发送给中心网络的C-DNS进行解析。
基于该第一规则，一方面，由于ULCL只将接收到的DNS请求发送给中心网络对应的C-PSA，而不是发送给多个网络(如一个或多个本地网络、中心网络)分别对应的PSA，也即每次只向一个网络请求解析DNS请求，因此可以减少DNS解析的次数，从而降低信令开销，进而提升解析效率。另一方面，由于该中心网络的C-DNS可以解析获得应用服务器的IP地址，因此提升了该DNS请求解析的成功率，因而进一步提升了DNS解析效率。
可选的，若ULCL上配置的本地网络的配置信息还包括本地网络的位置信息或服务区域信息，则上述第一规则中，若ULCL需要从多个本地网络中选择一个本地网络，则ULCL可以基于本地网络的位置信息或服务区域信息，从多个本地网络中选择一个距离UE最近的本地网络。
可选的，若ULCL上配置的本地网络的配置信息还包括本地网络的优先级信息，该优先级信息用于ULCL从至少一个本地网络中选择一个优先级最高的本地网络，则上述第一规则中，若ULCL需要从多个本地网络中选择一个本地网络，则ULCL可以基于本地网络的优先级信息，从多个本地网络中选择一个本地网络。
可选的，若根据上述第一规则，确定将DNS请求发送给C-DNS，则ULCL还可以在DNS请求中携带终端设备的位置信息，这样，C-DNS可以基于终端设备的位置信息解析DNS请求，解析得到的IP地址距离终端设备较近。
需要说明的是，如果在ULCL上配置了多种第一规则，则可以预先设置这些第一规则之间的优先级。
需要说明的是，以上第一规则可以是基于UE粒度配置的，也即不同的UE配置的第一规则可能相同，也可能不同。或者，以上第一规则可以是基于每UPF粒度配置的，也即同一UPF服务的不同UE所配置的第一规则都是相同的，但不同UPF服务的不同UE所配置的第一规则可以相同，也可以不同。
以下步骤409a至步骤409b是可选步骤。若上述步骤408中确定用于接收DNS请求的服务网络包括本地网络1，则执行以下步骤409a和步骤409b。若上述步骤408中确定用于接收DNS请求的服务网络部包括本地网络1，则不执行以下步骤409a和步骤409b。
步骤409a，ULCL向本地网络1对应的L-PSA1发送DNS请求。相应地，L-PSA1可以收到DNS请求。
参考图4，L-PSA1接收到DNS请求后，将DNS请求发送至本地网络1中的L-DNS进行解析。
当本地网络1中的L-DNS对DNS请求解析成功，也即获取到DNS请求中的应用标识对应的应用服务器的IP地址，则本地网络1中的L-DNS向L-PSA1发送IP地址，然后L-PSA1将IP地址发送给ULCL，进而ULCL将IP地址发给RAN，RAN将IP地址发给UE。
当本地网络1中的L-DNS解析失败，若本地网络1中的L-DNS与中心网络的C-DNS之间有接口，则可以将DNS请求发送至C-DNS进行解析，然后C-DNS将解析结果(即应用服务器的IP地址)发送至本地网络1的L-DNS，然后本地网络1中的L-DNS向L-PSA1发送IP地址，L-PSA1将IP地址发送给ULCL，进而ULCL将IP地址发给RAN，RAN将IP地址发给UE。
步骤409b，L-PSA1向ULCL发送响应信息。相应地，ULCL可以收到响应信息。
需要说明的是，当响应信息包含IP地址(可以是本地网络1的L-DNS解析得到的，也可以是C-DNS解析得到的)，表明L-PSA1对DNS请求解析成功。当响应信息不包含IP地址，表明L-PSA1对DNS请求解析失败。
以下步骤410a至步骤410b是可选步骤。若上述步骤408中确定用于接收DNS请求的服务网络包括中心网络，则执行以下步骤410a至步骤410b。若上述步骤408中确定用于接收DNS请求的服务网络不包括中心网络，则不执行以下步骤410a至步骤410b。
步骤410a，ULCL向中心网络对应的C-PSA发送DNS请求。相应地，C-PSA可以收到DNS请求。
参考图4，C-PSA接收到DNS请求后，将DNS请求发送至中心网络的C-DNS进行解析。一般地，中心网络部署有应用标识对应的应用服务器，因而可以解析成功。并且C-DNS上存储有一个应用标识与多个应用服务器的IP地址之间的映射关系，这里的多个应用服务器包括位于中心网络的应用服务器和位于本地网络中的应用服务器。
C-DNS对应用域名解析成功后，将相应的IP地址发送给C-PSA，C-PSA将IP地址发送给ULCL，进而ULCL将IP地址发给RAN，RAN将IP地址发给UE。
步骤410b，C-PSA向ULCL发送响应信息。相应地，ULCL可以收到响应信息。
需要说明的是，当响应信息包含IP地址，表明C-DNS对DNS请求解析成功。当DNS回复不包含IP地址，表明C-DNS对DNS请求解析失败。
步骤411，ULCL若收到多个IP地址，从中确定一个IP地址。
比如ULCL向多个UPF(如一个或多个L-PSA、C-PSA)发送了DNS请求，则会从每个UPF收到一个响应信息，有的响应信息携带IP地址(即解析成功)，有的响应信息没有携带IP地址(即解析失败)，如果ULCL接收到了多个IP地址，则从中选择一个IP地址(称为第一应用服务器的IP地址)。
作为一种实现方法，该第一应用服务器可以是距离UE最近的应用服务器。
步骤412，ULCL向UE发送IP地址。相应地，UE可以收到IP地址。
也即，ULCL向UE发送第一应用服务器的IP地址。
通过上述方案，ULCL可以基于配置的第一规则和本地网络的配置信息，选择一个或多个服务网络，并将接收到的DNS请求发送至选择的一个或多个服务网络对应的PSA。比如，当将DNS请求发送至选择的多个服务网络时，可以提升DNS请求的解析成功率。再比如，当将DNS请求发送给部署有DNS服务器的本地网络，或者发送给部署有具备递 归解析能力的DNS服务器的本地网络，也可以提升解析成功率。因此上述方案可以提升DNS解析的成功率。同时还可以得到一个距离终端设备最近的应用服务器的IP地址，可以减少时延，进而提升用户体验。
上述主要从各个网元之间交互的角度对本申请提供的方案进行了介绍。可以理解的是，上述实现各网元为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，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，本发明能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，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发明的范围。
可以理解的是，上述各个方法实施例中，对应由接入网设备实现的步骤或者操作，也可以由配置于接入网设备的部件(例如芯片或者电路)实现，对应由用户面网元实现的步骤或者操作，也可以由配置于用户面网元的部件(例如芯片或者电路)实现。
参考图5，为本申请实施例提供的一种通信装置的示意图。该装置用于实现上述图4实施例中对应分流网元(即ULCL)所执行的各个步骤，如图5所示，该装置500包括接收单元510、发送单元520和处理单元530。
接收单元510，用于接收来自终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括所述应用标识对应的应用服务器的IP地址。处理单元530，用于根据第一规则和至少一个本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器，所述第一规则为服务网络的确定规则。发送单元520，用于向所述至少一个服务网络对应的协议数据单元锚点PSA发送所述DNS请求；向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用服务器的IP地址包括所述第一应用服务器的IP地址。
在一种可能的实现方法中，所述第一规则是预配置在所述分流网元上的；或者，所述接收单元510，还用于从会话管理网元接收所述第一规则。
在一种可能的实现方法中，所述至少一个本地网络的配置信息是预配置在所述分流网元上的；或者，所述接收单元510，还用于从会话管理网元接收所述至少一个本地网络的配置信息。
在一种可能的实现方法中，所述第一规则是根据所述本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项确定的。
在一种可能的实现方法中，所述第一规则包括以下规则中的至少一种：
1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络。
3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；
所述第一规则还包括以下规则中的至少一种：
4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络；
7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
在一种可能的实现方法中，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；所述第一规则还包括以下规则中的至少一种：
10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
在一种可能的实现方法中，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
在一种可能的实现方法中，所述接收单元510接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。
可选的，上述通信装置500还可以包括存储单元，该存储单元用于存储数据或者指令(也可以称为代码或者程序)，上述各个单元可以和存储单元交互或者耦合，以实现对应的方法或者功能。例如，处理单元530可以读取存储单元中的数据或者指令，使得通信装 置实现上述实施例中的方法。
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。此外这些单元全部或部分可以集成在一起，也可以独立实现。这里所述的处理元件又可以成为处理器，可以是一种具有信号的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：一个或多个特定集成电路(Application Specific Integrated Circuit，ASIC)，或，一个或多个微处理器(digital singnal 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。
以上接收单元510是一种该装置的接口电路，用于从其他装置接收信号。例如，当该装置以芯片的方式实现时，该接收单元510是该芯片用于从其它芯片或装置接收信号的接口电路。
以上发送单元520是一种该装置的接口电路，用于向其他装置发送信号。例如，当该装置以芯片的方式实现时，该发送单元520是该芯片用于向其它芯片或装置发送信号的接口电路。
参考图6，为本申请实施例提供的一种通信装置的示意图。该装置用于实现上述图4实施例中对应会话管理网元(即SMF)所执行的各个步骤，如图6所示，该装置600包括收发单元610和处理单元620。
处理单元620，用于根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；确定终端设备能够接入的本地网络。收发单元610，用于向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。
可选的，上述通信装置600还可以包括存储单元，该存储单元用于存储数据或者指令(也可以称为代码或者程序)，上述各个单元可以和存储单元交互或者耦合，以实现对应的方法或者功能。例如，处理单元620可以读取存储单元中的数据或者指令，使得通信装置实现上述实施例中的方法。
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。此外这些单元全部或部分可以集成在一起，也可以独立实现。这里所述的处理元件又可以成为处理器，可以是一种具有信号的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ASIC，或，一个或多个DSP，或，一个或者多个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SOC的形式实现。
以上收发单元610是一种该装置的接口电路，用于向其他装置发送信号或从其他装置接收信号。例如，当该装置以芯片的方式实现时，该收发单元610是该芯片用于向其它芯片或装置发送信号、或用于从其它芯片或装置接收信号的接口电路。
参考图7，为本申请实施例提供的一种通信装置示意图，用于实现以上实施例中会话管理网元或分流网元的操作。如图7所示，该通信装置包括：处理器710和接口730，可选的，该通信装置还包括存储器720。接口730用于实现与其他设备进行通信。
以上实施例中会话管理网元或分流网元执行的方法可以通过处理器710调用存储器(可以是会话管理网元或分流网元中的存储器720，也可以是外部存储器)中存储的程序来实现。即，会话管理网元或分流网元可以包括处理器710，该处理器710通过调用存储器中的程序，以执行以上方法实施例中会话管理网元或分流网元执行的方法。这里的处理器可以是一种具有信号的处理能力的集成电路，例如CPU。会话管理网元或分流网元可以通过配置成实施以上方法的一个或多个集成电路来实现。例如：一个或多个ASIC，或，一个或多个微处理器DSP，或，一个或者多个FPGA等，或这些集成电路形式中至少两种的组合。或者，可以结合以上实现方式。
具体的，图5中的接收单元510、发送单元520和处理单元530的功能/实现过程可以通过图7所示的通信装置700中的处理器710调用存储器720中存储的计算机可执行指令来实现。或者，图5中的处理单元530的功能/实现过程可以通过图7所示的通信装置700中的处理器710调用存储器720中存储的计算机执行指令来实现，图5中的接收单元510、发送单元520的功能/实现过程可以通过图7中所示的通信装置700中的接口730来实现。
具体的，图6中的收发单元610和处理单元620的功能/实现过程可以通过图7所示的通信装置700中的处理器710调用存储器720中存储的计算机可执行指令来实现。或者，图6中的处理单元620的功能/实现过程可以通过图7所示的通信装置700中的处理器710调用存储器720中存储的计算机执行指令来实现，图6中的收发单元610的功能/实现过程可以通过图7中所示的通信装置700中的接口730来实现。
本领域普通技术人员可以理解：本申请中涉及的第一、第二等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实施例的范围，也表示先后顺序。“和/或”，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。字符“/”一般表示前后关联对象是一种“或”的关系。“至少一个”是指一个或者多个。至少两个是指两个或者多个。“至少一个”、“任意一个”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a,b,或c中的至少一项(个、种)，可以表示：a,b,c,a-b,a-c,b-c,或a-b-c，其中a,b,c可以是单个，也可以是多个。“多个”是指两个或两个以上，其它量词与之类似。
应理解，在本申请的各种实施例中，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，而不应对本发明实施例的实施过程构成任何限定。
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。
在上述实施例中，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指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照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。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。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包括一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
本申请实施例中所描述的各种说明性的逻辑单元和电路可以通过通用处理器，数字信号处理器，专用集成电路(ASIC)，现场可编程门阵列(FPGA)或其它可编程逻辑装置，离散门或晶体管逻辑，离散硬件部件，或上述任何组合的设计来实现或操作所描述的功能。通用处理器可以为微处理器，可选地，该通用处理器也可以为任何传统的处理器、控制器、微控制器或状态机。处理器也可以通过计算装置的组合来实现，例如数字信号处理器和微处理器，多个微处理器，一个或多个微处理器联合一个数字信号处理器核，或任何其它类似的配置来实现。
本申请实施例中所描述的方法或算法的步骤可以直接嵌入硬件、处理器执行的软件单元、或者这两者的结合。软件单元可以存储于随机存取存储器(Random Access Memory，RAM)、闪存、只读存储器(Read-Only Memory，ROM)、EPROM存储器、EEPROM存储器、寄存器、硬盘、可移动磁盘、CD-ROM或本领域中其它任意形式的存储媒介中。示例性地，存储媒介可以与处理器连接，以使得处理器可以从存储媒介中读取信息，并可以向存储媒介存写信息。可选地，存储媒介还可以集成到处理器中。处理器和存储媒介可以设置于ASIC中。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
在一个或多个示例性的设计中，本申请所描述的上述功能可以在硬件、软件、固件或这三者的任意组合来实现。如果在软件中实现，这些功能可以存储与电脑可读的媒介上，或以一个或多个指令或代码形式传输于电脑可读的媒介上。电脑可读媒介包括电脑存储媒介和便于使得让电脑程序从一个地方转移到其它地方的通信媒介。存储媒介可以是任何通用或特殊电脑可以接入访问的可用媒体。例如，这样的电脑可读媒体可以包括但不限于RAM、ROM、EEPROM、CD-ROM或其它光盘存储、磁盘存储或其它磁性存储装置，或其它任何可以用于承载或存储以指令或数据结构和其它可被通用或特殊电脑、或通用或特殊处理器读取形式的程序代码的媒介。此外，任何连接都可以被适当地定义为电脑可读媒介，例如，如果软件是从一个网站站点、服务器或其它远程资源通过一个同轴电缆、光纤电脑、双绞线、数字用户线(DSL)或以例如红外、无线和微波等无线方式传输的也被包含在所定义的电脑可读媒介中。所述的碟片(disk)和磁盘(disc)包括压缩磁盘、镭射盘、光盘、数字通用光盘(英文：Digital Versatile Disc，简称：DVD)、软盘和蓝光光盘，磁盘通常以磁性复制数据，而碟片通常以激光进行光学复制数据。上述的组合也可以包含在电脑可读媒介中。
本领域技术人员应该可以意识到，在上述一个或多个示例中，本申请所描述的功能可以用硬件、软件、固件或它们的任意组合来实现。当使用软件实现时，可以将这些功能存储在计算机可读介质中或者作为计算机可读介质上的一个或多个指令或代码进行传输。计算机可读介质包括计算机存储介质和通信介质，其中通信介质包括便于从一个地方向另一个地方传送计算机程序的任何介质。存储介质可以是通用或专用计算机能够存取的任何可用介质。
以上所述的具体实施方式，对本申请的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本申请的具体实施方式而已，并不用于限定本申请的保护范围，凡在本申请的技术方案的基础之上，所做的任何修改、等同替换、改进等，均应包括在本申请的保护范围之内。本申请说明书的上述描述可以使得本领域技术任何可以利用或实现本申请的内容，任何基于所公开内容的修改都应该被认为是本领域显而易见的，本申请所描述的基本原则可以应用到其它变形中而不偏离本申请的发明本质和范围。因此，本申请所公开的内容不仅仅局限于所描述的实施例和设计，还可以扩展到与本申请原则和所公开的新特征一致的最大范围。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的精神和范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包括这些改动和变型在内。

Claims (31)

  1. 一种域名系统DNS请求的解析方法，其特征在于，包括：
    分流网元接收来自终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；
    所述分流网元根据第一规则和至少一个本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器，所述第一规则为服务网络的确定规则；
    所述分流网元向所述至少一个服务网络对应的协议数据单元锚点PSA发送所述DNS请求；
    所述分流网元接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括所述应用标识对应的应用服务器的IP地址；
    所述分流网元向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用服务器的IP地址包括所述第一应用服务器的IP地址。
  2. 如权利要求1所述的方法，其特征在于，所述第一规则是预配置在所述分流网元上的；或者，
    所述分流网元从会话管理网元接收所述第一规则。
  3. 如权利要求1或2所述的方法，其特征在于，所述至少一个本地网络的配置信息是预配置在所述分流网元上的；或者，
    所述分流网元从会话管理网元接收所述至少一个本地网络的配置信息。
  4. 如权利要求1-3任一所述的方法，其特征在于，所述第一规则是根据所述本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项确定的。
  5. 如权利要求1-4任一所述的方法，其特征在于，所述第一规则包括以下规则中的至少一种：
    1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络；
    3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
  6. 如权利要求5所述的方法，其特征在于，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；
    所述第一规则还包括以下规则中的至少一种：
    4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地 DNS服务器，则将所述DNS请求发送给所述多个本地网络；
    7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
  7. 如权利要求5所述的方法，其特征在于，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；
    所述第一规则还包括以下规则中的至少一种：
    10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
  8. 如权利要求6或7所述的方法，其特征在于，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于所述分流网元从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
  9. 如权利要求1-7任一所述的方法，其特征在于，所述分流网元接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。
  10. 一种域名系统DNS请求的解析方法，其特征在于，包括：
    会话管理网元根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；
    所述会话管理网元确定终端设备能够接入的本地网络；
    所述会话管理网元向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。
  11. 一种通信装置，其特征在于，包括：
    接收单元，用于接收来自终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括所述应用标识对应的应用服务器的IP地址；
    处理单元，用于根据第一规则和至少一个本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器，所述第一规则为服务网络的确定规则；
    发送单元，用于向所述至少一个服务网络对应的协议数据单元锚点PSA发送所述DNS请求；向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用服务器的IP地址包括所述第一应用服务器的IP地址。
  12. 如权利要求11所述的装置，其特征在于，所述第一规则是预配置在所述分流网元上的；或者，
    所述接收单元，还用于从会话管理网元接收所述第一规则。
  13. 如权利要求11或12所述的装置，其特征在于，所述至少一个本地网络的配置信息是预配置在所述分流网元上的；或者，
    所述接收单元，还用于从会话管理网元接收所述至少一个本地网络的配置信息。
  14. 如权利要求11-13任一所述的装置，其特征在于，所述第一规则是根据所述本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项确定的。
  15. 如权利要求11-14任一所述的装置，其特征在于，所述第一规则包括以下规则中的至少一种：
    1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络；
    3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
  16. 如权利要求15所述的装置，其特征在于，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；
    所述第一规则还包括以下规则中的至少一种：
    4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络；
    7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
  17. 如权利要求15所述的装置，其特征在于，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；
    所述第一规则还包括以下规则中的至少一种：
    10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
  18. 如权利要求16或17所述的装置，其特征在于，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
  19. 如权利要求11-17任一所述的装置，其特征在于，所述接收单元接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。
  20. 一种通信装置，其特征在于，包括：
    处理单元，用于根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；以及确定终端设备能够接入的本地网络；
    发送单元，用于向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器。
  21. 一种通信系统，其特征在于，包括：
    会话管理网元，用于根据本地网络的本地DNS服务器部署、本地DNS服务器的解析能力、所述本地网络所包含的应用服务器和所述本地网络的位置中的至少一项，确定第一规则；确定终端设备能够接入的本地网络；向分流网元发送所述终端设备能够接入的本地网络的配置信息和所述第一规则，所述本地网络的配置信息包含所述本地网络的能力信息，所述本地网络的能力信息用于指示所述本地网络是否部署有本地DNS服务器；
    分流网元，用于从所述会话管理网元接收所述本地网络的配置信息和所述第一规则。
  22. 如权利要求21所述的系统，其特征在于，所述分流网元，还用于：
    接收来自所述终端设备的DNS请求，所述DNS请求包含应用标识，所述DNS请求用于请求所述应用标识对应的应用服务器的互联网协议IP地址；
    根据所述第一规则和所述本地网络的配置信息，确定至少一个服务网络，所述服务网络部署有DNS服务器；
    向所述至少一个服务网络对应的协议数据单元锚点PSA发送所述DNS请求；
    接收与所述至少一个DNS请求对应的响应信息，所述响应信息包括所述应用标识对应的应用服务器的IP地址；
    向所述终端设备发送第一应用服务器的IP地址，所述分流网元接收到的所述应用服务器的IP地址包括所述第一应用服务器的IP地址。
  23. 如权利要求21或22所述的系统，其特征在于，所述第一规则包括以下规则中的至少一种：
    1)、若所述至少一个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    2)、将所述DNS请求发送给所述至少一个本地网络中部署有本地DNS服务器的本地网络，以及发送给中心网络；
    3)、将所述DNS请求发送给所述至少一个本地网络中一个或多个部署有本地DNS服务器的本地网络。
  24. 如权利要求23所述的系统，其特征在于，所述本地网络的能力信息还用于指示当所述本地网络部署有本地DNS服务器时，所述本地DNS服务器是否支持递归DNS解析；
    所述第一规则还包括以下规则中的至少一种：
    4)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    5)、若所述至少一个本地网络中仅存在一个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    6)、若所述至少一个本地网络中存在多个本地网络部署有支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络；
    7)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则从中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    8)、若所述至少一个本地网络中仅存在一个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    9)、若所述至少一个本地网络中存在多个本地网络部署有不支持递归DNS解析的本地DNS服务器，则将所述DNS请求发送给所述多个本地网络。
  25. 如权利要求23所述的系统，其特征在于，所述本地网络的能力信息还用于指示所述本地网络部署的应用服务器的信息；
    所述第一规则还包括以下规则中的至少一种：
    10)、若所述至少一个本地网络中存在多个本地网络部署有所述应用标识对应的应用服务器、且所述多个本地网络部署有本地DNS服务器，则从所述至少一个本地网络中选择一个本地网络，将所述DNS请求发送给所述被选择的本地网络；
    11)、若所述至少一个本地网络中仅存在一个本地网络部署有所述应用标识对应的应用服务器、且所述本地网络部署有本地DNS服务器，则将所述DNS请求发送给所述本地网络；
    12)、若所述至少一个本地网络中存在一个或多个本地网络部署有所述应用标识对应的应用服务器、且所述一个或多个本地网络都没有部署本地DNS服务器，则将所述DNS请求发送给中心网络；
    13)、若所述至少一个本地网络都没有部署所述应用标识对应的应用服务器，则将所述DNS请求发送给中心网络。
  26. 如权利要求24或25所述的系统，其特征在于，所述本地网络的配置信息还包括所述本地网络的位置信息或服务区域信息，所述位置信息或服务区域信息用于所述分流网元从所述至少一个本地网络中选择一个距离所述终端设备最近的本地网络。
  27. 如权利要求21-26任一所述的系统，其特征在于，所述分流网元接收到的所述应用服务器的IP地址包括多个IP地址，第一应用服务器为所述多个IP地址对应的应用服务器中满足与所述终端设备距离要求的应用服务器。
  28. 一种计算机可读存储介质，其特征在于，包括计算机程序，当其在计算机上运行时，使得所述计算机执行如利要求1-9任一项所述的方法，或执行如利要求10所述的方法。
  29. 一种计算机程序产品，其特征在于，所述计算机程序产品包括计算机程序，当所述计算机程序在计算机上运行时，使得计算机执行如利要求1-9任一项所述的方法，或执行如利要求10所述的方法。
  30. 一种通信装置，其特征在于，包括用于执行如权利要求1-9任一项所述方法的模块，或用于执行如权利要求10所述方法的模块。
  31. 一种通信装置，其特征在于，包括处理器和接口电路，所述接口电路用于接收来自所述通信装置之外的其它通信装置的信号并传输至所述处理器或将来自所述处理器的信号发送给所述通信装置之外的其它通信装置，所述处理器通过逻辑电路或执行代码指令用于实现如权利要求1-9任一项所述的方法，或用于实现如权利要求10所述的方法。
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