WO2021051420A1 - 一种dns缓存记录的确定方法及装置 - Google Patents

一种dns缓存记录的确定方法及装置 Download PDF

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Publication number
WO2021051420A1
WO2021051420A1 PCT/CN2019/107155 CN2019107155W WO2021051420A1 WO 2021051420 A1 WO2021051420 A1 WO 2021051420A1 CN 2019107155 W CN2019107155 W CN 2019107155W WO 2021051420 A1 WO2021051420 A1 WO 2021051420A1
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WIPO (PCT)
Prior art keywords
address
dns
domain name
retention time
dnai
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PCT/CN2019/107155
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English (en)
French (fr)
Inventor
朱方园
李岩
倪慧
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to PCT/CN2019/107155 priority Critical patent/WO2021051420A1/zh
Publication of WO2021051420A1 publication Critical patent/WO2021051420A1/zh

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    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information

Definitions

  • This application relates to the field of mobile communication technology, and in particular to a method and device for determining DNS cache records.
  • the domain name system is a distributed host information database that provides mapping and conversion between domain names and Internet Protocol (IP) addresses, and can resolve domain names to corresponding IP addresses through DNS servers.
  • IP Internet Protocol
  • the terminal device can realize the access to the domain name through the domain name resolution service provided by the DNS server.
  • the process of domain name access is as follows: Take the terminal device accessing domain name A as an example.
  • the terminal device accesses the domain name A, query whether the IP address corresponding to the domain name A exists in the DNS cache record of the terminal device. If it exists, the terminal device You can directly obtain the IP address, and then access the domain name A through the IP address; if it does not exist, the terminal device can send a domain name resolution request to the DNS server, the domain name resolution request carries the domain name A, and the DNS server returns the corresponding domain name A
  • the terminal device can access the domain name A through the IP address.
  • the terminal device After obtaining the IP address corresponding to the domain name, the terminal device generates and caches a DNS cache record.
  • the DNS cache record is used to indicate the correspondence between the domain name and the IP address.
  • the terminal device maintains a corresponding time to live (TTL) for each cached DNS cache record.
  • TTL time to live
  • TTL indicates the storage or cache time of the DNS cache record corresponding to the IP address in the cache of the terminal device, where 0 means that it can only be transmitted but cannot be cached.
  • the terminal device can directly obtain the IP address corresponding to the domain name based on the DNS cache record; if the TTL of the DNS cache record is exceeded Later, when the terminal device needs to access the domain name again, the terminal device needs to resolve the IP address corresponding to the domain name through the DNS server through the above process.
  • the terminal device when the terminal device obtains the DNS cache record corresponding to a certain domain name before moving, if the TTL of the DNS cache record is still valid after the terminal device is moved, the terminal device may be due to the DNS cache not being updated or DNS The retention time corresponding to the cache record is not appropriate, which results in the application corresponding to the domain name being unable to be accessed at the current location. Therefore, based on the DNS cache record, there is currently no good solution for how to implement the terminal device to access the application in the application server corresponding to the IP address nearby.
  • This application provides a method and device for determining a DNS cache record, which is used to implement an application in which a terminal device accesses an application server corresponding to an IP address nearby.
  • this application provides a method for determining a DNS cache record, including: a terminal device determines that DNAI has changed; the terminal device updates a DNS cache record, and the updated DNS cache record includes at least the domain name of the application or the corresponding domain name Is one of the Internet Protocol IP addresses of the application server, and the IP address corresponds to the changed DNAI.
  • the terminal device obtains a new DNS cache record after determining that the DNAI has changed.
  • the IP address corresponding to the application domain name contained in the new DNS cache record is the IP address of the application server corresponding to the changed DNAI, that is, after the change The IP address of the application server deployed at the DNAI. Therefore, the subsequent terminal device will access the application through the new IP address, realizing the nearby access service.
  • the terminal device determining that the DNAI has changed includes: the terminal device receives a DNAI change instruction, and determines that the DNAI has changed according to the DNAI change instruction; or, the terminal device determines where the DNAI has changed after moving If the DNAI corresponding to the position of is different from the DNAI corresponding to the position before the movement, it is determined that the DNAI has changed.
  • the terminal device updating DNS cache records includes: the terminal device sends an update cache request, the update cache request includes the domain name of the application; the terminal device receives an update cache response, The update cache response includes the IP address; the terminal device updates the DNS cache record according to the IP address.
  • this application provides a method for determining DNS cache records, including: a core network element receives a first DNS query request from a terminal device, the first DNS query request includes a domain name and an address of a DNS server; The core network element sends a second DNS query request to the DNS server, where the second DNS query request includes the domain name; the core network element receives from the DNS server the name of the first application server corresponding to the domain name IP address and a first retention time, where the first retention time is the retention time of the DNS cache record corresponding to the IP address; the core network element determines that the first condition is met, and modifies the first retention time to the first 2.
  • the core network element sends the IP address and the second retention time to the terminal device, and the IP address and the second retention time are used by the terminal device to determine the IP address The corresponding DNS cache record.
  • the core network element can modify the retention time of the DNS cache record corresponding to the IP address corresponding to the domain name, so that the UE can access the application server application corresponding to the IP address based on the modified retention time, that is, through The modified retention time controls the UE to access the application in the application server corresponding to the IP address nearby.
  • this application provides another method for determining DNS cache records, including:
  • the DNS server receives a first DNS query request from the terminal device, where the first DNS query request includes the domain name and the address of the DNS server;
  • the DNS server determines that the first condition is met, and modifies the first retention time to the second retention time
  • the DNS server sends the IP address and the second retention time to the terminal device, where the IP address and the second retention time are used by the terminal device to determine a DNS cache record corresponding to the IP address.
  • the first condition includes but is not limited to:
  • the first condition includes: the mobility attribute of the terminal device is high mobility.
  • the session management network element obtains the mobility attribute of the terminal device from a mobility management network element or a data management network element.
  • the first condition includes: the first mobile edge computing MEC platform where the first application server corresponding to the domain name is located and the second MEC platform where the second application server corresponding to the domain name is located cannot communicate with each other.
  • the second retention time is less than the first retention time, and the second retention time is equal to 0, or a positive number not greater than a preset first threshold.
  • Method 3 The first condition includes: the IP address is an anycast address.
  • the second retention time is greater than the first retention time, and the second retention time is not less than a preset second threshold.
  • the first condition includes: the first application server corresponding to the domain name is deployed on the MEC platform.
  • the first condition includes: the mobility attribute of the terminal device is high mobility, and the first application server corresponding to the domain name is deployed on the MEC platform.
  • the session management network element obtains the mobility attribute of the terminal device from a mobility management network element or a data management network element.
  • the first condition includes: the first MEC platform where the first application server corresponding to the domain name is located and the second MEC platform where the second application server corresponding to the domain name is located cannot communicate with each other, and the The first application server corresponding to the domain name is deployed on the MEC platform.
  • the second retention time is less than the first retention time, and the second retention time is equal to 0, or a positive number not greater than a preset first threshold.
  • the first condition includes: the IP address is an anycast address, and the first application server corresponding to the domain name is deployed on the MEC platform.
  • the second retention time is greater than the first retention time, and the second retention time is not less than a preset second threshold.
  • this application provides a device for determining DNS cache records.
  • the device may be a terminal device or a chip for the terminal device.
  • the device has the function of realizing the above-mentioned first aspect or each embodiment of the first aspect. This function can be realized by hardware, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules corresponding to the above-mentioned functions.
  • this application provides a device for determining a DNS cache record.
  • 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 or each embodiment of the second aspect. This function can be realized by hardware, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules corresponding to the above-mentioned functions.
  • this application provides a device for determining DNS cache records.
  • the device may be a DNS server or a chip for the DNS server.
  • the device has the function of realizing the foregoing third aspect or the embodiments of the third aspect. This function can be realized by hardware, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules corresponding to the above-mentioned functions.
  • the present application provides a device for determining DNS cache records, including: a processor and a memory; the memory is used to store computer execution instructions, and when the device is running, the processor executes the computer execution instructions stored in the memory , So that the device executes the methods described in the above aspects.
  • the device may be a terminal device, or a chip used for terminal devices, or a session management network element, or a chip used for session management network element, or a DNS server, or a chip used for a DNS server.
  • the present application provides a device for determining a DNS cache record, including: a unit or means for performing each step of the foregoing aspects.
  • the device can be a session management network element, a terminal device, or a DNS server.
  • the present application provides an apparatus for determining a DNS cache record, including a processor and an interface circuit, the processor is configured to implement the methods described in the foregoing aspects through the interface circuit.
  • the processor includes one or more.
  • the device may be a chip used for session management network elements, terminal equipment, or DNS server.
  • the present application provides an apparatus for determining DNS cache records, including a processor, configured to be connected to a memory, and configured to call a program stored in the memory to execute the methods described in the foregoing aspects.
  • the memory can be located inside the device or outside the device.
  • the processor includes one or more.
  • the device may be a terminal device, or a chip used for a terminal device, or a session management network element, or a session management network element, or a chip used for a DNS server.
  • the present application also provides a computer-readable storage medium having instructions stored in the computer-readable storage medium, which when run on a computer, cause a processor to execute the methods described in the foregoing aspects.
  • this application also provides a computer program product including instructions, which when run on a computer, causes the computer to execute the methods described in the above aspects.
  • the present application also provides a chip system, including a processor, configured to execute the methods described in the foregoing aspects.
  • Figure 1 is a schematic diagram of a possible network architecture applicable to this application
  • FIG. 2 is a schematic diagram of another possible network architecture to which this application applies;
  • Figure 3 is a schematic diagram of a domain name resolution scenario
  • FIG. 4A is a schematic flowchart of a method for determining a DNS cache record provided by this application
  • FIG. 4B is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • FIG. 5 is a schematic flowchart of another method for determining DNS cache records provided by this application.
  • FIG. 6 is a schematic flowchart of another method for determining DNS cache records provided by this application.
  • FIG. 7 is a schematic flowchart of another method for determining DNS cache records provided by this application.
  • FIG. 8 is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • FIG. 9 is a schematic diagram of application access provided by this application.
  • FIG. 10 is a schematic flowchart of another method for determining DNS cache records provided by this application.
  • FIG. 11 is a schematic diagram of a device for determining a DNS cache record provided by this application.
  • FIG. 12 is a schematic diagram of another device for determining a DNS cache record provided by this application.
  • FIG. 13 is a schematic diagram of a terminal device provided by this application.
  • FIG. 14 is a schematic diagram of a session management network element provided by this application.
  • FIG. 1 it is a schematic diagram of the fifth generation (5G) network architecture based on a service-oriented architecture.
  • the 5G network architecture shown in FIG. 1 may include three parts, namely a terminal equipment part, a data network (DN), and an operator network part.
  • DN data network
  • Operator network part The functions of some of the network elements are briefly introduced below.
  • the operator network may include one or more of the following network elements: network exposure function (NEF) network elements, policy control function (PCF) network elements, unified data management (unified data management) , UDM) network element, network storage function (Network Repository Function, NRF) network element, application function (AF) network element, access and mobility management function (access and mobility management function, AMF) network element, session Management function (session management function, SMF) network element, radio access network (RAN), unified data repository (Unified Data Repository, UDR) (not shown in the figure), network data analysis function network element ( Network Data Analytics Function (NWDAF) network elements and user plane function (UPF) network elements, etc.
  • NEF network exposure function
  • PCF policy control function
  • UDM network element
  • NRF Network Repository Function
  • AF application function
  • AMF access and mobility management function
  • SMF session Management function
  • RAN radio access network
  • UDR Unified Data Repository
  • NWDAF Network Data Analytics Function
  • UPF user plane function
  • Terminal device also called user equipment (user equipment, UE), is a device with wireless transceiver function, which can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; it can also be deployed on water It can also be deployed in the air (such as airplanes, balloons, and satellites).
  • the terminal device may be a mobile phone (mobile phone), a tablet computer (pad), a computer with wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, an industrial control (industrial control) Wireless terminals in ), wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grid, and wireless terminals in transportation safety , Wireless terminals in smart cities, wireless terminals in smart homes, etc.
  • the above-mentioned terminal equipment can establish a connection with the operator's network through an interface (such as N1, etc.) provided by the operator's network, and use the data and/or voice services provided by the operator's 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 terminal equipment, and may provide other services such as data and/or voice for the terminal equipment.
  • the specific form of expression of the above-mentioned third party can be determined according to actual application scenarios, and is not limited here.
  • RAN is a sub-network of an operator's network, and 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 wireless communication functions for terminal devices, 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 stations (gnodeB, gNB), evolved node B (evolved node B, eNB), radio network controller (RNC), node B in 5G (node B, NB), base station controller (BSC), 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), transmission point (transmitting point, TP), mobile switching center, etc.
  • next-generation base stations gnodeB, gNB
  • evolved node B evolved node B
  • RNC radio network controller
  • node B in 5G node B, NB
  • BSC base station controller
  • BTS base transceiver station
  • home base station for example, home evolved nodeB, or home node B, HNB
  • TRP transmission point
  • AMF network element responsible for user mobility management, including mobility status management, assigning user temporary identities, authenticating and authorizing users.
  • SMF network element responsible for UPF selection, UPF reselection, IP address allocation, responsible for bearer establishment, modification and release, and QoS control.
  • UPF network elements support all or part of the following functions: Interconnect protocol data unit (PDU) sessions with data networks; packet routing and forwarding (for example, support for Uplink classifier and forwarding of traffic to the data network, support for Branching point to support multi-homed PDU session); data packet inspection.
  • PDU Interconnect protocol data unit
  • packet routing and forwarding for example, support for Uplink classifier and forwarding of traffic to the data network, support for Branching point to support multi-homed PDU session
  • data packet inspection for example, support for Uplink classifier and forwarding of traffic to the data network, support for Branching point to support multi-homed PDU session.
  • a DN is a network located outside the operator's network.
  • the operator's network can access multiple DNs, and multiple services can be deployed on the DN, which can provide data and/or voice services for terminal devices.
  • DN is a private network of a smart factory.
  • the sensors installed in the workshop of the smart factory can be terminal devices.
  • a control server for the sensors is deployed in the DN, and the control server can provide services for the sensors.
  • the sensor can communicate with the control server, obtain instructions from the control server, and transmit the collected sensor data to the control server according to the instructions.
  • DN is the 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 company's internal office network.
  • the UDM network element is responsible for managing the contracted data, and when the contracted data is modified, it is responsible for notifying the corresponding network element.
  • UDR is used to store and retrieve contract data, policy data and public structure data, etc.; for UDM, PCF and NEF to obtain relevant data.
  • UDR must be able to have different data access authentication mechanisms for different types of data such as contract data and policy data to ensure the security of data access; UDR must be able to return and carry appropriate data for illegal servicing operations or data access requests The failure response for the reason value.
  • NEF network elements are mainly used to support the opening of capabilities and events.
  • the AF network element provides certain application layer services to the UE.
  • the AF provides services to the UE, it has requirements for QoS policies and charging policies (Charging) and needs to notify the network.
  • AF also needs application-related information fed back from the core network.
  • PCF network elements include policy control decision-making and flow-based charging control functions, including user subscription data management functions, policy control functions, charging policy control functions, QoS control, etc.
  • the NRF network element can be used to provide the network element discovery function, and provide the network element information corresponding to the network element type based on the request of other network elements.
  • NRF also provides network element management services, such as network element registration, update, de-registration, and network element status subscription and push.
  • the NWDAF network element is used to provide the big data analysis information of the contracted terminal according to the request of the policy module PCF, and help the PCF optimize the strategy control; it can provide the big data analysis information according to the slice dimension.
  • Nnef, Nnrf, Npcf, Nudm, Nnwdaf, Naf, Nausf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface serial numbers.
  • the meanings of these interface serial numbers can be referred to the meanings defined in the 3rd generation partnership project (3rd generation partnership project, 3GPP) standard protocol, which is not limited here.
  • FIG. 2 it is a schematic diagram of a 5G network architecture based on a point-to-point interface.
  • the interfaces between the various network elements in Figure 2 are point-to-point interfaces rather than service-oriented interfaces.
  • FIG. 2 also includes other network elements, such as NEF network elements, NRF network elements, UDR network elements, and NWDAF network elements, which are not shown in FIG. 2.
  • the interface between the UE and the AMF network element is called the N1 interface
  • the interface between the AMF network element and the RAN device is called the N2 interface
  • the interface between the RAN device and the UPF network element It can be called N3 interface
  • the interface between SMF network element and UPF network element is called N4 interface
  • the interface between PCF network element and AF network element is called N5 interface
  • the interface between UPF network element and DN is called N6 Interface
  • the interface between SMF network element and PCF network element is called N7 interface
  • the interface between AMF network element and UDM network element is called N8 interface
  • the interface between different UPF network elements is called N9 interface
  • UDM network element The interface with the SMF network element is called the N10 interface
  • the interface between the AMF network element and the SMF network element is called the N11 interface
  • the interface between different AMF network elements is called the N14 interface
  • the one between the AMF network element and the PCF network element The interface between is called N15 interface.
  • the aforementioned network elements or functions may be network elements in hardware devices, software functions running on dedicated hardware, or virtualization functions instantiated on a platform (for example, a cloud platform).
  • a platform for example, a cloud platform.
  • the foregoing network element or function may be implemented by one device, or jointly implemented by multiple devices, or may be a functional module in one device, which is not specifically limited in the embodiment of the present application.
  • the mobility management network element, session management network element, policy control network element, application function network element, access network device, network opening function network element, and user plane network element in this application may be those in Figure 1 or Figure 2 respectively.
  • AMF, SMF, PCF, AF, RAN, NEF, UPF, or future communications such as the 6th generation (6G) network with the above-mentioned functions of AMF, SMF, PCF, AF, RAN, NEF, UPF Yuan, this application is not limited.
  • mobility management network elements, session management network elements, policy control network elements, application function network elements, access network equipment, network open function network elements, and user plane network elements are respectively the above-mentioned AMF, SMF, and SMF.
  • the terminal device is referred to as UE for short in this application.
  • the SMF will send the address of a DNS server to the UE; after that, the UE will use the address of the DNS server for domain name query.
  • TS 23.501 when the UE moves to the location of the Mobile Edge Compute (MEC) platform-1, SMF inserts the tapping point (uplink classifier (uplink classifier) according to the data network access identifier (DNAI) of the current location).
  • uplink Classifier uplink Classifier
  • UL CL Uplink Classifier
  • BP branch point
  • the UE requests to access an application on the MEC platform (such as MEC platform 1) (assuming the application is application-1, domain name: domain name A), it needs to first query the IP address corresponding to domain name A of the application, and domain name A corresponds to The IP address is the IP address of the application server corresponding to domain name A.
  • the UE sends the domain name A to the DNS server, and the DNS server resolves the domain name A to IP-1 according to the current location of the UE.
  • the current location of the UE can be the identifier of the MEC platform 1 (indicated by DNAI), which is not limited in the present invention.
  • the DNS server returns TTL to the UE, and the UE uses IP-1 to communicate with the application. This record (the record includes the IP-1 and TTL corresponding to domain name A) will be kept in the UE's cache.
  • the UE moves and switches to another MEC platform (such as MEC platform 2), if the UE still wants to access application-1 (the domain name of application-1 is domain name A unchanged), when the TTL in the DNS cache record on the UE side has not expired According to the cache record, the UE still finds that the domain name A corresponds to IP-1, and the UE continues to use IP-1 to access the service, but another application server of the domain name A may be deployed on the MEC platform where the UE is currently located (assuming this application server The IP address is IP-2), so IP-2 is closer to the UE. Therefore, if the UE uses IP-1 to access the application, the service access path will not be optimized.
  • MEC platform 2 such as MEC platform 2
  • the present application provides a method for determining DNS cache records. As shown in FIG. 4A, the method includes the following steps:
  • step 401a the UE determines that the DNAI has changed.
  • Step 402b The UE updates the DNS cache record.
  • the updated DNS cache record includes at least one of the domain name of the application or the Internet Protocol IP address of the application server corresponding to the domain name, and the IP address corresponds to the changed DNAI.
  • a DNS cache record includes at least a domain name or an IP address corresponding to the domain name, and the IP address is the IP address of the application server.
  • the method for the UE to update the DNS cache record includes but is not limited to:
  • Method 1 Replace part of the information in the original DNS cache record.
  • the original DNS cache record includes domain name A and IP address 1, and then IP address 1 in the original DNS cache record is replaced with IP address 2, but domain name A remains unchanged, so the updated DNS cache record includes domain name A and IP Address 2.
  • the original DNS cache record includes domain name A and IP address 1
  • the original DNS cache record is deleted first, and then a new DNS cache record is generated.
  • the new DNS cache record includes domain name A and IP address 2.
  • the terminal device obtains a new DNS cache record after determining that the DNAI has changed.
  • the IP address corresponding to the application domain name contained in the new DNS cache record is the IP address of the application server corresponding to the changed DNAI, that is, after the change The IP address of the application server deployed at the DNAI. Therefore, the subsequent terminal device will access the application through the new IP address, realizing the nearby access service.
  • the method for the UE to determine that the DNAI has changed includes but is not limited to the following two methods.
  • Method 1 The UE receives the DNAI change indication, and determines that the DNAI has changed according to the DNAI change indication.
  • SMF obtains the DNAI-1 corresponding to the UE's location information before moving, and the DNAI-2 corresponding to the UE's location information after it moves. If DNAI-2 is different from DNAI-1, SMF generates a DNAI change indication, and then The SMF sends the DNAI change indication to the UE through the AMF to notify the UE that the DNAI has changed.
  • DNAI-1 and DNAI-2 respectively identify two different MEC platforms.
  • Method 2 The UE determines that the DNAI corresponding to the position after the movement is different from the DNAI corresponding to the position before the movement, and then determines that the DNAI has changed.
  • the AMF will allocate a registration area for the UE.
  • the registration area contains the TAI list.
  • the AMF sends the TAI contained in the registration area and the DNAI corresponding to the TAI to the UE, and the UE stores the TAI.
  • Correspondence with DNAI As an example, the corresponding relationship between TAI and DNAI stored in the UE is shown in Table 1.
  • the registration area of the UE includes TAI-1, TAI-2, TAI-3, TAI-4, TAI-5, and TAI-6, where , DNAI corresponding to TAI-1, TAI-2 and TAI-3 is DNAI-1, and DNAI corresponding to TAI-4, TAI-5 and TAI-6 is DNAI-2.
  • TAI included in the registration area DNAI TAI-1, TAI-2, TAI-3 DNAI-1 TAI-4, TAI-5, TAI-6 DNAI-2
  • the TAI corresponding to the location of the UE is TAI-1, which corresponds to DNAI-1; after the UE moves, the TAI corresponding to the location of the UE is TAI-5, which corresponds to DNAI-2, and the UE determines DNAI-2 Unlike DNAI-1, the UE determines that DNAI has changed.
  • the method for the UE to update the DNS cache record in the above step 402a may be: the UE sends an update cache request to the network side, the update cache request includes the domain name of the application; then the UE receives the update cache from the network side In response, the update cache response includes an IP address.
  • the cache update response may also include a retention time, where the retention time is the retention time of the DNS cache record corresponding to the IP address, and then the UE updates the IP address to update the DNS cache record, and the IP address is the application server's IP address, the IP address of the application server corresponds to the changed DNAI.
  • the above-mentioned cache update request may also be a DNS query request or a request for other message names
  • the above-mentioned cache update response may also be a DNS query response or a response to other message names, which is not limited in the present invention.
  • this application provides yet another method for determining DNS cache records. As shown in FIG. 4B, the method includes the following steps:
  • Step 401b The UE sends a first DNS query request to the core network element, where the first DNS query request includes the domain name and the address of the DNS server.
  • the core network element can receive the first DNS query request.
  • the core network element here can be UPF or SMF.
  • Step 402b The core network element sends a second DNS query request to the DNS server, where the first DNS query request includes a domain name.
  • the DNS server can receive the second DNS query request.
  • the core network element may send a second DNS query request to the DNS server based on the address of the DNS server in the first DNS query request.
  • Step 403b The core network element receives from the DNS server the IP address of the first application server corresponding to the domain name and the first retention time, where the first retention time is the retention time of the DNS cache record corresponding to the IP address.
  • the DNS server receives the second DNS query request, obtains the domain name therein, and resolves the domain name into an IP address. Specifically, it is resolved to the IP address of the first application server corresponding to the domain name. Then the DNS server sends the IP address of the first application server corresponding to the domain name and the first retention time to the core network element.
  • Step 404b The core network element determines that the first condition is satisfied, and modifies the first retention time to the second retention time.
  • Step 405b The core network element sends the IP address corresponding to the domain name and the second retention time to the UE.
  • the UE can receive the IP address and the second retention time corresponding to the domain name.
  • the UE After receiving the IP address and the second retention time corresponding to the domain name, the UE can determine the DNS cache record corresponding to the IP address.
  • the core network element can modify the retention time of the DNS cache record corresponding to the IP address corresponding to the domain name, so that the UE can access the application server application corresponding to the IP address based on the modified retention time, that is, through The modified retention time controls the UE to access the application in the application server corresponding to the IP address nearby.
  • step 404b For the foregoing step 404b, three different implementation methods are given below.
  • the first condition includes: the mobility attribute of the UE is high mobility.
  • the first retention time is modified to the second retention time
  • the second retention time here is less than the first retention time.
  • the second retention time is equal to 0 or a positive number not greater than the preset first threshold, where the first threshold is a relatively small positive number.
  • the UE may not save the DNS cache record (when the second retention time is equal to 0) or the DNS cache record saved by the UE Expires soon (when the second retention time is a positive number less than the preset threshold), if the UE needs to access the application corresponding to the domain name again, it will not obtain the IP address corresponding to the domain name locally, but trigger the UE to resend the DNS server
  • the domain name is used to obtain the IP address corresponding to the domain name, and the DNS server can send the IP address of the application server closest to the UE corresponding to the domain name to the UE, so that the UE can access the application server corresponding to the domain name nearby.
  • the core network element may obtain the mobility attribute of the UE from AMF or NWDAF.
  • the first condition includes: the first MEC platform where the first application server corresponding to the domain name is located and the second MEC platform where the second application server corresponding to the domain name is located cannot achieve intercommunication.
  • the first MEC platform here is the MEC platform corresponding to the location of the UE after the movement
  • the second MEC platform is the MEC platform corresponding to the location of the UE before the movement.
  • the UE may not save the DNS cache record (when the second retention time is equal to 0) or the DNS cache record saved by the UE will quickly become invalid (when the second retention time is not greater than The positive number of the preset first threshold), if the UE needs to access the application corresponding to the domain name again, it will not obtain the IP address corresponding to the domain name locally, but triggers the UE to resend the domain name to the DNS server to obtain the IP corresponding to the domain name
  • the DNS server can send the IP address of the application server closest to the UE corresponding to the domain name to the UE, so that the UE can access the application server corresponding to the domain name nearby (that is, the application of the application server at the location of the first MEC platform) .
  • the first condition includes: the IP address corresponding to the domain name requested by the UE is an anycast address.
  • anycast is defined as: when a unicast address is assigned to more than one interface, send The message to this interface is routed by the network to the "nearest" target interface measured by the routing protocol), then it means that when the data message of this application is routed on the core network, UPF will select the nearest application server to implement the route. In this case, even if the UE switches to another MEC platform and the TTL does not expire, the UE uses the anycast address of the application server for business access, and the UPF can still route the data message to the new MEC platform according to the anycast address Because the new MEC platform is closer to UPF.
  • the core network element can modify the first retention time to the second retention time, And the second retention time is greater than the first retention time, and the second retention time is not less than a preset second threshold, where the second threshold is a relatively large positive number. That is, the retention time of the DNS cache record corresponding to the IP address is modified to a larger value (this value is the second retention time), so that the UE can achieve nearby access based on the IP address of the DNS cache record (that is, the anycast address) Application of the application server of the MEC platform.
  • the core network element may not modify the retention time, that is, the core network element receives the first retention time, and then sends the first retention time to the UE. Therefore, if the first retention time expires, the UE obtains the application server corresponding to the IP address by means of DNS query. At this time, since the IP address is an anycast address, it can still access the application in the nearby application server.
  • the first condition includes: the first application server corresponding to the domain name is deployed on the MEC platform.
  • the first condition includes: the mobility attribute of the terminal device is high mobility, and the first application server corresponding to the domain name is deployed on the MEC platform.
  • This method is a combination of the foregoing realization method 1 and the realization method 4.
  • the foregoing realization method 1 and realization method 4 please refer to the description of the foregoing realization method 1 and realization method 4, which will not be repeated here.
  • the first condition includes: the first MEC platform where the first application server corresponding to the domain name is located and the second MEC platform where the second application server corresponding to the domain name is located cannot communicate with each other, and all The first application server corresponding to the domain name is deployed on the MEC platform.
  • This method is a combination of the foregoing realization method 2 and realization method 4.
  • This method is a combination of the foregoing realization method 2 and realization method 4.
  • the first condition includes: the IP address is an anycast address, and the first application server corresponding to the domain name is deployed on the MEC platform.
  • This method is a combination of the foregoing realization method 3 and realization method 4.
  • This method is a combination of the foregoing realization method 3 and realization method 4.
  • the core network element may also determine whether the mobility attribute of the UE or the information of the MEC platform where the application server corresponding to the domain name is located, or whether the IP address is any
  • the DNS server determines whether the first condition is satisfied. When the first condition is satisfied, the DNS server modifies the first retention time to the second retention time, and then sends the second retention time to the DNS server. UE.
  • the core network element determines that the above-mentioned first condition is satisfied, it sends instruction information to the DNS server, etc., for instructing the DNS server to set the first retention time Modify it to the second retention time, and then send the second retention time to the UE.
  • FIG. 5 it is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • This embodiment is a specific implementation of the embodiment shown in FIG. 4A.
  • the main inventions of this embodiment are as follows: SMF judges that the UE has moved from the first DNAI to the second DNAI according to the DNAI corresponding to the current location of the UE, that is, the mobility of the UE causes the DNAI change to occur, and the SMF informs the UE that the DNAI change has occurred (by N1 The SM container is delivered to the UE). After the UE receives the DNAI change instruction, it deletes the DNS cache record and updates the DNS cache.
  • the method includes the following steps:
  • Step 501 The DNS server in the network stores the correspondence between the deployment location of the application (the deployment location of the application is identified by DNAI), the domain name corresponding to the application, and the IP address corresponding to the domain name.
  • the DNS server here may be a centralized DNS deployed by an operator (for example, a remote DNS server connected to UPF-1 in FIG. 5), or a local DNS server deployed on the MEC platform.
  • Step 502 PDU session establishment process.
  • the UE initiates a session establishment process, carrying PDU Session ID (PDU Session ID), single network slice selection assistance information (S-NSSAI) and Data Network Name (Data Network Name, DNN) and other parameters; AMF according to S-NSSAI and DNN select SMF, and combine the permanent identity of the UE, the location information of the UE (the tracking area identity (TAI) is used to represent the location information of the UE), the PDU session identity, S-NSSAI and DNN, etc.
  • the parameters are sent to the SMF, and the SMF selects the UPF for the UE as the PDU Session Anchor (PSA) of the session.
  • the UPF is the PSA-1 in FIG. 5.
  • Step 503 The SMF invokes the service operation Namf_Communication_N1N2MessageTransfer of the AMF, which carries the PDU session identifier and the N1 SM container (N1 SM container).
  • the N1 SM container contains the address of the DNS server, and the address of the DNS server is the address of the remote DNS server in the figure.
  • the AMF sends a non-access stratum (NAS) message to the UE through the RAN, carrying the PDU session identifier, N1 SM container, and sends the DNS server address sent by the SMF to the UE through the N1 SM container.
  • NAS non-access stratum
  • step 504 the UE has moved and moved to the deployment location of the MEC platform.
  • SMF obtains the location information of the UE from the AMF, and determines DNAI-1 according to the TAI where the current UE is located. DNAI-1 can be used to identify MEC platform-1.
  • SMF decides to select the offload point UPF and the new user plane anchor point PSA-2 for the current session, so as to achieve local offload.
  • the offload point UPF can be an uplink classifier (Uplink Classifier, UL CL) or a branch point (Branching point, BP), and the new user plane anchor point PSA-2 and MEC platform-1 can perform data transmission.
  • Uplink Classifier Uplink Classifier
  • BP branch point
  • the new user plane anchor point PSA-2 and MEC platform-1 can perform data transmission.
  • Step 505 The SMF sends an N4 session to the offload point UPF (ie, UL CL or BP).
  • the N4 session includes a forwarding rule, and the forwarding rule is used to instruct the offload point UPF to perform the following actions:
  • Step 506 since the UE has obtained the address of the DNS server in step 503, if the UE needs to access an application, the UE will initiate a DNS query request according to the address of the DNS server.
  • the source address in the DNS query request is the IP of the UE.
  • Address is the address of the remote DNS server.
  • the offloading point UPF After the offloading point UPF receives the DNS query request from the UE, it replaces the destination address in the DNS query request with the address of the remote DNS server according to the forwarding rules sent by the SMF in step 505 Is the address of the DNS server located on the MEC platform-1.
  • the tapping point UPF sends the DNS query request to PSA-2.
  • PSA-2 addresses the DNS server according to the destination address (that is, the address of the DNS server on the MEC platform-1) and receives the DNS query response.
  • PSA-2 sends the DNS query response to the UE through the tapping point UPF, and the DNS query response It carries the IP address and TTL of the application, and the IP address of the application is the IP address of the application server on the MEC platform-1 corresponding to the domain name.
  • step 506 after receiving the DNS query request from the UE, the offloading point UPF or PSA-2 reports the domain name included in the DNS query request to the SMF. If the UE initiates DNS query requests corresponding to multiple domain names on the MEC platform-1, the offload point UPF or PSA-2 can report multiple domain names to SMF respectively.
  • step 507 the UE has moved and moved to the deployment location of another MEC platform.
  • the SMF obtains the location information of the UE from the AMF, and determines DNAI-2 according to the TAI where the current UE is located.
  • DNAI-2 can be used to identify MEC platform-2. So far, SMF has learned that the UE has moved from DNAI-1 to DNAI-2, that is, the UE has moved from MEC platform-1 to MEC platform-2.
  • Step 508 Insertion of UL CL/BP and local PSA-3.
  • the SMF judges that the DNAI change has occurred in the mobility of the UE, and decides to select a new offload point UPF and a new user plane anchor point PSA-3 for the current session, thereby realizing local offload.
  • the split point UPF here can be ULCL or BP, and the new user plane anchor points PSA-3 and MEC platform-2 can perform data transmission.
  • Step 509 The SMF sends a forwarding rule to the new offload point UPF, where the forwarding rule is used to instruct the new offload point UPF to perform the following actions:
  • the SMF invokes the service operation Namf_Communication_N1N2MessageTransfer of the AMF, which carries the PDU Session ID, N1 SM container.
  • the N1 SM container contains a DNAI change indication (DNAI change indication).
  • Step 511 The AMF sends a NAS message to the UE through the RAN, carrying the PDU Session ID, N1 SM container, and sends the DNAI change indication sent by the SMF to the UE through the N1 SM container.
  • step 512 the UE learns that the DNAI change has occurred through the DNAI change indication included in the N1 SM container in the NAS message, and the UE deletes the DNS cache record.
  • the deletion of the DNS cache record by the UE can be understood as the UE deletes the DNS cache records corresponding to all domain names according to the DNAI change instruction.
  • step 506 if the SMF receives the domain name record requested by the UE on the MEC platform-1, in step 510, the SMF may send the DNAI change indication and the aforementioned domain name record (maybe the UE has queried multiple domain names) through N1
  • the SM container is sent to the UE.
  • the UE can delete only the cache record corresponding to the domain name contained in the N1 SM container according to the domain name contained in the received domain name record and the DNAI change instruction.
  • the UE may not delete the cache record corresponding to the domain name, that is, the UE may continue to use the IP address corresponding to the domain name of the application contained in the cache record to access the application.
  • the UE initiates a cache update request, carrying the domain name, source address (IP address of the UE), and destination address (address of the remote DNS server).
  • the cache update request may also be a DNS query request or other message name request, which is not limited in the present invention.
  • the offloading point UPF replaces the destination address in the DNS query request from the address of the remote DNS server with the address of the remote DNS server according to the forwarding rules sent by the SMF in step 509. The address of the DNS server on the MEC platform-2.
  • the offloading point UPF sends the DNS query request to PSA-3.
  • PSA-3 addresses the DNS server according to the destination address (the address of the DNS server on the MEC platform-2).
  • Step 514 The DNS server sends an update cache response and sends it to the UE through PSA-3.
  • the cache update response may also be a DNS query response or a response to other message names, which is not limited in the present invention.
  • the PSA-3 sends the DNS query response to the UE through the tapping point UPF.
  • the DNS query response includes the IP address and TTL of the application, and the IP address of the application is the IP address of the application server on the MEC platform-2 corresponding to the domain name.
  • the UE performs DNS cache update according to the DNAI change instruction, which can ensure that after the UE moves, it can access local applications nearby, thereby improving communication efficiency.
  • FIG. 6 a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • This embodiment is a specific implementation of the embodiment shown in FIG. 4A.
  • the AMF stores all the correspondences (full set) of TAI and DNAI under the service area of the AMF.
  • the AMF allocates a registration area (TAI list) for the UE, and at the same time delivers the corresponding relationship (subset) of the TAI list and DNAI corresponding to the UE registration area to the UE.
  • the UE judges the DNAI based on the current TAI.
  • the DNS cache record is deleted and the DNS cache record update is initiated.
  • the method includes the following steps:
  • Step 600 The DNS in the network stores the correspondence between the deployment location of the application (the deployment location of the application is identified by DNAI), the domain name corresponding to the application, and the IP address corresponding to the domain name.
  • the DNS here can be a centralized DNS server deployed by the operator (the remote DNS server in the figure), or it can be a local DNS server deployed on the MEC platform.
  • the AMF stores the correspondence between all TAIs and DNAIs under the service area of the AMF.
  • step 601 the UE initiates a registration procedure, and the RAN sends a registration request message of the UE to the AMF network element.
  • step 602 the AMF network element allocates a registration area (Registration Area) for the UE, where the Registration Area is composed of a TAI list (TAI list). At the same time, the AMF determines the registration area in the Registration Area according to the stored correspondence between TAI and DNAI and the Registration Area. Correspondence between TAI and DNAI. For a detailed description of this step, refer to Method 2 in step 401a.
  • step 603 the AMF sends a registration acceptance message to the UE, and at the same time sends the corresponding relationship between the TAI and DNAI in the Registration Area to the UE through the registration acceptance message.
  • the AMF may also send indication information to the UE to indicate which DNAI locations of the UE are deployed with the MEC platform. That is, the indication information is used to indicate the DNAI corresponding to the deployed MEC platform.
  • step 604 the UE initiates a session establishment process, carrying the PDU session identifier, S-NSSAI and DNN and other parameters; AMF selects SMF according to S-NSSAI and DNN, and sets the permanent identifier of the UE and the location information of the UE (using TAI to represent the UE The location information), the PDU session identifier, S-NSSAI and DNN and other parameters are sent to the SMF.
  • the SMF selects the UPF for the UE as the PSA of the session, and the UPF is the PSA-1 in FIG. 6.
  • Step 605 The SMF calls the AMF service operation Namf_Communication_N1N2MessageTransfer, which carries the PDU session identifier, N1 SM container.
  • the N1 SM container contains the address of the DNS server.
  • the address of the DNS server is the address of the remote DNS server in the figure.
  • the AMF sends a NAS message to the UE through the RAN, carrying the PDU session identifier, N1 SM container, and sends the address of the DNS server sent by the SMF to the UE through the N1 SM container.
  • Steps 606 to 609 are the same as steps 504 to 506 in the embodiment of FIG. 5.
  • the SMF obtains the location information of the UE from the AMF, and determines DNAI-2 according to the current location of the UE. Insertion of ULCL/BP and local PSA-3.
  • the UE has moved and moved to the deployment location of another MEC platform. It is assumed that the current location is the deployment location of the MEC platform-2.
  • the SMF obtains the location information of the UE from the AMF, and determines DNAI-2 according to the current location of the UE. SMF judges that the DNAI change has occurred in the mobility of the UE, and decides to select a new offload point UPF and a new user plane anchor point PSA-3 for the current session, thereby realizing local offload.
  • the split point UPF here can be ULCL or BP, and the new user plane anchor points PSA-3 and MEC platform-2 can perform data transmission.
  • SMF sends forwarding rules to the new offload point UPF, which forwarding rules are used to instruct the new offload point UPF to perform the following actions:
  • Step 611 The UE judges the DNAI according to the current TAI. If the UE finds that the DNAI has changed due to the movement of the UE, for example, the UE moves from the first TAI to the second TAI, the first TAI corresponds to the first DNAI (for example, DNAI1), and the second TAI Corresponding to the second DNAI (for example, DNAI2), then it means that the movement of the UE causes the DNAI to change.
  • the first TAI corresponds to the first DNAI (for example, DNAI1)
  • the second TAI Corresponding to the second DNAI for example, DNAI2
  • step 612 the UE learns that the DNAI has changed, and the UE deletes the DNS cache record.
  • the deletion of the DNS cache record by the UE can be understood as the UE deletes the DNS cache records corresponding to all domain names according to the DNAI change instruction.
  • Step 613 The UE initiates a cache update request, carrying the domain name, source address (IP address of the UE), and destination address (address of the remote DNS server).
  • the cache update request can also be a DNS query request or a request for other message names.
  • the invention is not limited. Take the UE initiated DNS query request as an example. After receiving the UE’s DNS query request, the offloading point UPF will replace the destination address in the DNS query request from the address of the remote DNS server with the address of the remote DNS server according to the forwarding rules sent by the SMF in step 610. The address of the DNS server on the MEC platform-2. At the same time, the offloading point UPF sends the DNS query request to PSA-3.
  • PSA-3 addresses the DNS server according to the destination address (the address of the DNS server on the MEC platform-2).
  • the DNS server sends an update cache response and sends it to the UE through PSA-3.
  • the cache update response may also be a DNS query response or a response to other message names, which is not limited in the present invention.
  • the PSA-3 receives the DNS query response, and the PSA-3 sends the DNS query response to the UE through the tapping point UPF.
  • the DNS query response includes the IP address and TTL of the application, and the IP address of the application is the IP address of the application server on the MEC platform-2 corresponding to the domain name.
  • the UE perceives the relationship between TAI and DNAI (MEC platform), and when the UE switches DNAI, it deletes the DNS record and initiates a DNS cache update.
  • FIG. 7 there is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • This embodiment is a specific implementation of the embodiment shown in FIG. 4B.
  • the deployment locations of these applications can be identified by DNAI, that is, the UE signs up for some applications deployed on specific DNAI locations, and SMF is based on the UE’s Mobility attributes (for example, SMF obtains the mobility pattern of the UE from AMF/NWDAF). For high-mobility UEs (such UEs are easier to switch MEC platforms frequently), SMF resolves DNS messages.
  • SMF modifies the TTL in the DNS query response, for example, set it to 0 or a smaller value, so that the UE will re-initiate a domain name resolution request to the DNS server every time, thus ensuring that the UE every time When doing business visits, you can access the local applications corresponding to your current location.
  • the method includes the following steps:
  • step 701 the UE initiates a session establishment process, carrying the PDU session identifier, S-NSSAI and DNN and other parameters; AMF selects the SMF according to the S-NSSAI and DNN, and sets the permanent identifier of the UE and the location information of the UE (TAI is used to represent the UE The location information), the PDU session identifier, S-NSSAI and DNN and other parameters are sent to the SMF, and the SMF selects the UPF for the UE as the PSA of the session.
  • AMF selects the SMF according to the S-NSSAI and DNN, and sets the permanent identifier of the UE and the location information of the UE (TAI is used to represent the UE The location information), the PDU session identifier, S-NSSAI and DNN and other parameters are sent to the SMF, and the SMF selects the UPF for the UE as the PSA of the session.
  • the SMF sends the address of the DNS server to the UE, and the sending method refers to the embodiment of FIG. 5 or FIG. 6.
  • Step 702 Optionally, the SMF obtains the mobility attribute of the UE.
  • the SMF obtains the application type subscribed by the UE and the deployment location DNAI corresponding to the application from the PCF. If the UE subscribes to the applications deployed on the MEC platform (the DNAI corresponding to the deployment location of these applications is a special DNAI), the SMF triggers the acquisition of the mobility attributes of the UE.
  • Implementation method 1 The SMF invokes the service operation Namf_EventExposure_Subscribe of the AMF network element, which carries the UE's permanent subscription identifier (Subscription Permanent Identifier, SUPI), and requests the UE's mobility attributes from the AMF.
  • AMF returns Namf_EventExposure_Notify, which contains the SUPI and mobility attributes of the UE.
  • Implementation method 2 SMF calls the service operation Nnwdaf_AnalyticsSubscription_Subscribe, which carries the SUPI of the UE, and requests the mobility attributes of the UE to be obtained from the NWDAF. After NWDAF collects data on the UE, performs big data analysis, and obtains the mobility attributes of the UE, NWDAF returns Nnwdaf_AnalyticsSubscription_Notify to the SMF, which carries the SUPI and mobility attributes of the UE.
  • the mobility attribute can identify the mobility attribute of the UE, for example, the mobility is high, the mobility is medium, and the mobility is low.
  • step 703 the SMF sends an N4 reply to the UPF, and the N4 reply includes the forwarding rule of the DNS query request.
  • the SMF sends a forwarding rule to the UPF corresponding to the session of the UE, and the forwarding rule is used to instruct the UPF to forward the DNS query request to the SMF for processing after receiving the DNS query request from the UE.
  • the UE initiates a DNS query request based on the DNS server address obtained in step 701.
  • the DNS query request carries the domain name requested by the UE, the source address (the UE’s IP address), and the destination address (the DNS server address).
  • UPF receives After the DNS query request of the UE, the DNS query request is sent to the SMF for processing according to the forwarding rule sent by the SMF in step 703.
  • the SMF sends the query request to the DNS server, and receives the DNS query response from the DNS server, which carries the IP address and the first TTL corresponding to the domain name of the application.
  • the first TTL is the retention time of the DNS cache record corresponding to the IP address determined by the DNS server.
  • Step 705 After the SMF receives the DNS query response sent by the DNS server, when the SMF network element determines that the application corresponding to the domain name is deployed on the MEC platform according to the domain name requested by the UE, optionally, further, the SMF network element determines that the UE is For high-mobility UE, the SMF sets the TTL in the DNS query response to 0 or a smaller value.
  • the DNS query response includes the first TTL and the IP address corresponding to the domain name
  • the SMF modifies the first TTL to the second TTL
  • the SMF sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the second TTL is less than the first TTL
  • the second TTL is 0 or a smaller value.
  • the second TTL is the retention time of the DNS cache record corresponding to the IP address determined by the SMF.
  • the method for SMF to determine the second TTL may be: SMF modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the SMF, and the second TTL is not greater than the preset first TTL.
  • a positive number for a threshold Exemplarily, the first threshold may be 100 seconds or 1 minute.
  • the SMF also determines the second TTL according to other methods, which is not limited in the present invention.
  • Step 706 The SMF sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the UE After the UE receives the TTL, if the TTL is equal to 0, it means that the record of this DNS query does not need to be cached. If the TTL is relatively small, the UE automatically deletes this DNS cache record when the TTL expires.
  • SMF requests the mobility attributes of the UE from the AMF, or the SMF requests the mobility attributes of the UE from the NWDAF.
  • SMF parses DNS messages. If the UE requests the domain name corresponding to the application deployed on the MEC platform, SMF modifies the TTL in the DNS query response, for example, set it to 0 or a smaller value, so that the UE every time It will re-initiate a domain name resolution request to the DNS server, so it can be guaranteed that the UE can access the local application corresponding to the current location every time the UE performs business access.
  • the first network element when the first network element (UPF or DNS server) receives the DNS query request of the UE, the first network element can modify the first retention time to the second retention time. Time, and then send the second retention time to the UE.
  • step 703 to step 706 in the embodiment of FIG. 7 can be replaced with the following steps 703' to step 706':
  • the SMF sends the first indication information to the UPF.
  • the first indication information is used to instruct the UPF to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform after receiving the DNS query request from the UE. If the application corresponding to the domain name requested by the UE is deployed on the MEC platform, then UPF needs to modify the TTL carried in the DNS response.
  • the SMF sends the first indication information to the UPF.
  • the UE initiates a DNS query request according to the DNS server address obtained in step 701.
  • the DNS query request carries the domain name requested by the UE, the source address (the IP address of the UE), the destination address (the address of the DNS server), and the UPF receives After the DNS query request to the UE, it is sent to the DNS server, and the DNS query response is received from the DNS server, which carries the IP address and the first TTL corresponding to the domain name of the application.
  • the first TTL is the retention time of the DNS cache record corresponding to the IP address determined by the DNS server.
  • step 705' the UPF judges that the application corresponding to the domain name requested by the UE is deployed on the MEC platform according to the first indication information sent by the SMF in step 703', where the UPF judges that the application corresponding to the domain name requested by the UE is deployed on the MEC platform.
  • UPF can store configuration information, the configuration information includes which domain names corresponding applications are deployed on the MEC platform, or UPF receives second indication information sent by SMF, the second indication information is used to indicate which domain names corresponding applications are deployed on the MEC platform ,
  • the present invention is not limited.
  • UPF modifies the first TTL to the second TTL.
  • the method for UPF to determine the second TTL may be: UPF modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the UPF, and the second TTL is not greater than the preset first TTL.
  • a positive number for a threshold Exemplarily, the first threshold may be 100 seconds or 1 minute. It should be noted that the UPF also determines the second TTL according to other methods, which is not limited in the present invention.
  • step 706' the UPF sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the second TTL is less than the first TTL, and the second TTL is 0 or a smaller value.
  • the second TTL is the retention time of the DNS cache record corresponding to the IP address determined by UPF.
  • the UE After the UE receives the TTL, if the TTL is equal to 0, it means that the record of this DNS query does not need to be cached. If the TTL is relatively small, the UE automatically deletes this DNS cache record when the TTL expires.
  • steps 703 to 706 in the embodiment of FIG. 7 can be replaced with the following steps 703" to 706":
  • Step 703 the UE will initiate a DNS query request according to the DNS server address obtained in step 701.
  • the DNS query request carries the domain name requested by the UE, the source address (the IP address of the UE), the destination address (the address of the DNS server), and the UPF receives After the DNS query request to the UE, it is sent to the DNS server.
  • Step 704" the DNS server determines the IP address corresponding to the domain name of the application.
  • the DNS server determines whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform.
  • the method for the DNS server to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform may be: the DNS server can store configuration information, and the configuration information contains which domain names corresponding applications are deployed on the MEC platform, which is not limited by the present invention .
  • the DNS server may further determine whether the mobility attribute of the UE is high mobility.
  • the DNS server judging whether the mobility attribute of the UE is high mobility includes but is not limited to the following methods:
  • Method 1 Receive indication information sent by SMF or UPF, where the indication information is used to indicate that the mobility attribute of the UE is high mobility.
  • Method 2 The mobility attribute of the UE sent by the SMF or UPF is received, and the mobility attribute of the UE is high mobility.
  • Method 3 Obtain the mobility attributes of the UE through the capability opening platform.
  • Step 705" if the DNS server determines that the mobility attribute of the UE is high mobility, and determines that the application corresponding to the domain name requested by the UE is deployed on the MEC platform, then the retention time of the DNS cache record corresponding to the IP address (first TTL ) Is modified to the second TTL.
  • the DNS server can also decide whether to modify the TTL only according to whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform.
  • the method for the DNS server to determine the second TTL may be: the DNS server modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the DNS server, and the second TTL is not greater than the preset value. Set the positive number of the first threshold. Exemplarily, the first threshold may be 100 seconds or 1 minute. It should be noted that the DNS server also determines the second TTL according to other methods, which is not limited in the present invention.
  • Step 706 The DNS server sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the second TTL is less than the first TTL, and the second TTL is 0 or a smaller value.
  • the UE After the UE receives the TTL, if the TTL is equal to 0, it means that the record of this DNS query does not need to be cached. If the TTL is relatively small, the UE automatically deletes this DNS cache record when the TTL expires.
  • FIG. 8 it is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • This embodiment is a specific implementation of the embodiment shown in FIG. 4B.
  • SMF configures the connectivity between different MEC platforms (DNAI), for example, whether the gateways close to different MEC platforms can directly establish a tunnel connection, if different MEC platforms (DNAI) cannot be directly connected
  • DNAI different MEC platforms
  • the SMF can set the TTL to 0 or less In this way, the UE will re-initiate a domain name resolution request to the DNS server every time, thereby ensuring that the UE can access the local application corresponding to the current location every time the UE performs business access.
  • the UE initiates a DNS query at the location of the old MEC platform and obtains the IP address and TTL corresponding to the application on the old MEC platform.
  • Scenario 1 When the UE moves to the location of the new MEC platform, if a data forwarding channel can be established between the old MEC platform and the new MEC platform, then when the TTL does not expire, the UE uses the IP address corresponding to the application on the old MEC platform For business access, the network elements on the new MEC platform can still route data to the old MEC platform, that is, the UE routes data to the old MEC platform through the new MEC platform, although this data forwarding path is not Not optimized, but at least the routing of business data can be guaranteed.
  • Scenario 2 When the UE moves to the location of the new MEC platform, if the data forwarding channel cannot be established between the old MEC platform and the new MEC platform, it can be understood that the two different MEC platforms are isolated. Allow data forwarding between each other. Then, when the UE moves to the location of the new MEC platform and the TTL does not expire, if the UE uses the corresponding IP address of the application on the old MEC platform for business access, data forwarding cannot be established between the old MEC platform and the new MEC platform Channels, that is, network elements on the new MEC platform cannot implement data routing, which will cause business interruption.
  • SMF determines that data forwarding or routing cannot be achieved between the MEC platform currently accessed by the UE and other MEC platforms, then SMF can modify the TTL in the DNS query response, for example, set it to 0 or a smaller value. This can ensure that the UE initiates a DNS cache update at the location of the new MEC platform, and uses the new IP address for business access.
  • the method includes the following steps:
  • the SMF configures the connectivity between different MEC platforms (the deployment location of the MEC platform is identified by DNAI).
  • the connectivity of different MEC platforms can be understood as whether the gateways of different MEC platforms can directly establish tunnel connections. Realize data forwarding.
  • step 801 the AF stores the correspondence between the deployment location of the application on the MEC platform (the deployment location of the application is represented by DNAI) and the domain name in the UDR through the NEF.
  • step 802 the UE initiates a session establishment process, carrying the PDU session identifier, S-NSSAI and DNN and other parameters; AMF selects SMF based on S-NSSAI and DNN, and combines the UE’s SUPI and UE’s location information (TAI is used to represent the UE The location information), PDU session identifier, S-NSSAI and DNN and other parameters are sent to SMF.
  • AMF selects SMF based on S-NSSAI and DNN, and combines the UE’s SUPI and UE’s location information (TAI is used to represent the UE The location information), PDU session identifier, S-NSSAI and DNN and other parameters are sent to SMF.
  • step 803a the SMF sends a policy control establishment request to the PCF.
  • the PCF can receive the policy control establishment request.
  • the policy control establishment request may be, for example, Npcf_SMPolicyControl_Create Request.
  • Npcf_SMPolicyControl_CreateRequest For example, in the process of establishing the session, the SMF calls the PCF service operation Npcf_SMPolicyControl_CreateRequest, requesting to obtain the policy information related to the session from the PCF.
  • step 803b the PCF sends a query request to the UDR.
  • the UDR sends a query response to the PCF.
  • the query response includes the corresponding relationship between the deployment location (represented by DNAI) of the application in step 801 and the domain name.
  • the query request may be Nudr_DM_Query, for example.
  • the PCF calls the UDR service operation Nudr_DM_Query to obtain information related to the application subscribed by the UE from the UDR, which includes the corresponding relationship between the deployment location of the application in step 801 (indicated by DNAI) and the domain name.
  • step 801c the PCF generates a PCC rule according to the deployment location and domain name of the application, and sends a policy control establishment response to the SMF, which carries the PCC rule.
  • the policy control establishment response may be Npcf_SMPolicyControl_Create Response, for example.
  • PCF sends to SMF by calling Npcf_SMPolicyControl_Create Response.
  • SMF saves PCC rules, which include the deployment location and domain name of the application signed by the UE.
  • PCC rules may also include other rules, such as charging rules and message forwarding rules. , And which DNAI can perform ULCL/BP insertion and so on.
  • step 803d the SMF selects UPF as the PSA of the session according to parameters such as S-NSSAI and DNN, and the SMF sends an N4 session establishment request to the UPF, which carries the forwarding rule of the DNS query request, and is used to instruct the UPF to receive the DNS of the UE.
  • the DNS query request is forwarded to SMF.
  • the SMF continues to perform other steps in the session establishment process, which is not related to the present invention, and will not be repeated here.
  • step 804 after the session is established, the UE sends a DNS query request to the core network according to its own business requirements, and initiates a DNS query for an application.
  • the DNS query request carries the domain name corresponding to the application.
  • the DNS query request of the UE is forwarded to the SMF.
  • step 805 if the SMF detects that the domain name requested by the UE is included in the correspondence between the deployment location and domain name of the application obtained from step 803, the SMF determines whether the deployment location of the application corresponding to the domain name requested by the UE is located between the MEC platform and other MEC platforms Whether it can not be connected between the two.
  • Connectivity means that data can be forwarded or routed.
  • the SMF forwards the DNS query request to the DNS server, and receives the DNS query response from the DNS server.
  • the DNS query response includes the IP address corresponding to the domain name and the first TTL.
  • the first TTL is the retention time of the DNS cache record corresponding to the IP address determined by the DNS server.
  • the SMF judges in step 806: if the SMF determines that the MEC platform where the application deployment location corresponding to the domain name requested by the UE is located cannot be connected to other MEC platforms, the SMF can modify the first TTL in the DNS query response to The second TTL, for example, the second TTL can be 0 or a smaller value, which can ensure that the UE moves to a new MEC platform location. After the second TTL expires, DNS cache update is initiated and the new IP address is used for service access. Wherein, the second TTL is the retention time of the DNS cache record corresponding to the IP address determined by SMF.
  • the method for SMF to determine the second TTL may be: SMF modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the SMF, and the second TTL is not greater than the preset first TTL.
  • a positive number for a threshold Exemplarily, the first threshold may be 100 seconds or 1 minute.
  • the SMF also determines the second TTL according to other methods, which is not limited in the present invention.
  • step 808 the SMF sends a DNS query response to the UE.
  • the DNS query response includes the IP address corresponding to the domain name and the second TTL.
  • the SMF can determine whether to modify the TTL in the DNS query response according to the connectivity between the MEC platform accessed by the UE and other MEC platforms, thereby triggering the UE to update the DNS cache.
  • the first network element when the first network element (UPF or DNS server) receives the DNS query request from the UE, the first network element may modify the first retention time to the second retention time. , And then send the second retention time to the UE.
  • steps 803 to 808 in the embodiment of Fig. 8 are replaced by the following steps 803' to 806':
  • Step 803' during the establishment of the session, the SMF invokes the PCF servicing operation Npcf_SMPolicyControl_Create Request, requesting to obtain the policy information related to the session from the PCF, and the PCF invokes the UDR servicing operation Nudr_DM_Query to obtain the application related to the UE contracted by the UDR
  • the information contains the correspondence between the deployment location of the application in step 801 (represented by DNAI) and the domain name.
  • PCF generates PCC rules based on the deployment location and domain name of the application, and sends them to SMF through Npcf_SMPolicyControl_Create Response.
  • the SMF saves the PCC rules, which include the deployment location and domain name of the application signed by the UE; in addition, the PCC rules may also include other rules, such as , Charging rules, packet forwarding rules, and which DNAI can perform ULCL/BP insertion, etc.
  • the SMF selects the UPF as the PSA of the session according to parameters such as S-NSSAI and DNN, and the SMF sends an N4 session establishment request to the UPF, which carries the first indication information.
  • the first indication information is used to instruct the UPF to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform after receiving the DNS query request from the UE, if the application corresponding to the domain name requested by the UE is deployed on the MEC platform, and If the MEC platform cannot communicate with other MEC platforms, UPF needs to modify the TTL carried in the DNS response.
  • the UE initiates a DNS query request.
  • the DNS query request carries the domain name requested by the UE, the source address (the UE’s IP address), and the destination address (the DNS server address).
  • the UPF receives the UE’s DNS query request, it sends it to DNS server, and receives a DNS query response from the DNS server, which carries the IP address and the first TTL corresponding to the domain name of the application.
  • the first TTL is the retention time of the DNS cache record corresponding to the IP address determined by the DNS server.
  • step 805' the UPF judges that the application corresponding to the domain name requested by the UE is deployed on the MEC platform according to the first indication information sent by the SMF in step 803', wherein the UPF judges that the application corresponding to the domain name requested by the UE is deployed on the MEC platform.
  • UPF can store configuration information, the configuration information includes which domain names corresponding applications are deployed on the MEC platform, or UPF receives second indication information sent by SMF, the second indication information is used to indicate which domain names corresponding applications are deployed on the MEC platform ,
  • the present invention is not limited.
  • the UPF judges that the MEC platform where the application corresponding to the domain name requested by the UE is located cannot be connected with other MEC platforms.
  • the connection here means that data forwarding or routing can be realized.
  • UPF modifies the first TTL to the second TTL.
  • the second TTL is the retention time of the DNS cache record corresponding to the IP address determined by UPF.
  • the method for UPF to determine the second TTL may be: UPF modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the UPF, and the second TTL is not greater than the preset first TTL.
  • a positive number for a threshold Exemplarily, the first threshold may be 100 seconds or 1 minute. It should be noted that the UPF also determines the second TTL according to other methods, which is not limited in the present invention.
  • the second TTL of the UPF and the IP address corresponding to the domain name are sent to the UE through the DNS query response.
  • the second TTL is less than the first TTL, and the second TTL is 0 or a smaller value.
  • the second TTL is the retention time of the DNS cache record corresponding to the IP address determined by UPF.
  • step 803 to step 805 in the embodiment of FIG. 8 can be replaced with the following steps 803" to step 806":
  • Step 803 in the process of establishing the session, SMF calls PCF's servicing operation Npcf_SMPolicyControl_Create Request, requesting to obtain the policy information related to the session from the PCF, and PCF calls the UDR servicing operation Nudr_DM_Query to obtain the application related to the UE contracted by the UDR
  • the information contains the correspondence between the deployment location of the application in step 801 (indicated by DNAI) and the domain name.
  • PCF generates PCC rules based on the deployment location and domain name of the application, and sends them to SMF through Npcf_SMPolicyControl_Create Response, and SMF saves
  • the PCC rules include the deployment location and domain name of the application signed by the UE; in addition, the PCC rules may also include other rules, such as charging rules, packet forwarding rules, and which DNAI can perform ULCL/BP insertion, and so on.
  • the SMF selects the UPF as the PSA of the session according to parameters such as S-NSSAI and DNN, and the SMF sends an N4 session establishment request to the UPF.
  • Step 804" the UE initiates a DNS query request.
  • the DNS query request carries the domain name requested by the UE, the source address (the IP address of the UE), and the destination address (the address of the DNS server).
  • the UPF receives the DNS query request from the UE, it sends it to DNS server.
  • Step 805" the DNS server determines the IP address corresponding to the domain name of the application.
  • the DNS server determines whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform.
  • the method for the DNS server to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform may be: the DNS server can store configuration information, and the configuration information contains which domain names corresponding applications are deployed on the MEC platform, which is not limited by the present invention .
  • the DNS server determines that the MEC platform where the application corresponding to the domain name requested by the UE is located cannot be connected to other MEC platforms.
  • the connection here means that data forwarding or routing can be realized.
  • the DNS server modifies the retention time (first TTL) of the DNS cache record corresponding to the IP address to the second TTL.
  • the method for the DNS server to determine the second TTL may be: the DNS server modifies the first TTL to 0 based on the local policy (that is, the second TTL is 0), or configures the first threshold on the DNS server, and the second TTL is not greater than the preset value. Set the positive number of the first threshold. Exemplarily, the first threshold may be 100 seconds or 1 minute. It should be noted that the DNS server also determines the second TTL according to other methods, which is not limited in the present invention.
  • Step 806 the DNS server sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the second TTL is less than the first TTL, and the second TTL is 0 or a smaller value.
  • the UE After the UE receives the TTL, if the TTL is equal to 0, it means that the record of this DNS query does not need to be cached. If the TTL is relatively small, the UE automatically deletes this DNS cache record when the TTL expires.
  • FIG. 10 it is a schematic flowchart of another method for determining a DNS cache record provided by this application.
  • This embodiment is a specific implementation of the embodiment shown in FIG. 4B.
  • the difference between this embodiment and the embodiments in FIG. 7 and FIG. 8 is: how the previous two embodiments ensure that the UE initiates a DNS cache update on the new MEC platform as much as possible to use the new IP address for business access.
  • the embodiment in FIG. 10 provides another scenario, that is, a scenario where the IP address is an anycast address.
  • the scheme of this embodiment is summarized as follows: SMF learns that the application corresponding to the domain name requested by the UE has anycast address on different MEC platforms, and the SMF modifies the TTL in the DNS query response to a larger value, so that even before the TTL expires, the UE uses With the anycast address access service, UPF can still access local applications nearby based on the anycast address.
  • the method includes the following steps:
  • Step 1001 The MEC platform stores the application deployment location (represented by DNAI), the corresponding relationship between the domain name and the IP address in the UDR through NEF.
  • the IP address is an anycast address.
  • step 1002 the UE initiates a session establishment process, carrying PDU session identifier, S-NSSAI and DNN and other parameters; AMF selects SMF according to S-NSSAI and DNN, and combines the UE’s SUPI and UE’s location information (TAI is used to represent the UE The location information), PDU session identifier, S-NSSAI and DNN and other parameters are sent to SMF.
  • AMF selects SMF according to S-NSSAI and DNN, and combines the UE’s SUPI and UE’s location information (TAI is used to represent the UE The location information), PDU session identifier, S-NSSAI and DNN and other parameters are sent to SMF.
  • Step 1003a the SMF sends a policy control establishment request to the PCF.
  • the PCF can receive the policy control establishment request.
  • the policy control establishment request may be, for example, Npcf_SMPolicyControl_Create Request.
  • Npcf_SMPolicyControl_CreateRequest For example, in the process of establishing the session, the SMF calls the PCF service operation Npcf_SMPolicyControl_CreateRequest, requesting to obtain the policy information related to the session from the PCF.
  • step 1003b the PCF sends a query request to the UDR.
  • the UDR sends a query response to the PCF.
  • the query response includes the deployment location of the application in step 1001 (represented by DNAI), the corresponding relationship between the domain name and the IP address.
  • the PCF calls the UDR service operation Nudr_DM_Query to obtain information related to the application subscribed by the UE from the UDR, including the deployment location of the application in step 1001 (indicated by DNAI), the correspondence between the domain name and the IP address.
  • step 1003c the PCF generates a PCC rule according to the deployment location, domain name, and IP address of the application, and sends a policy control establishment response to the SMF, which carries the PCC rule.
  • the policy control establishment response may be Npcf_SMPolicyControl_Create Response, for example.
  • PCF sends Npcf_SMPolicyControl_Create Response to SMF by calling Npcf_SMPolicyControl_Create.
  • the SMF saves the PCC rules, which include the deployment location, domain name, and IP address of the application signed by the UE.
  • the PCC rules may also include other rules, such as charging rules, reporting Text forwarding rules, and which DNAI can perform ULCL/BP insertion, etc.
  • the SMF selects the UPF network element as the PSA of the session according to the parameters such as S-NSSAI and DNN, and the SMF sends an N4 session establishment request to the UPF, which carries the forwarding rule of the DNS query request, which is used to instruct the UPF to receive the UE After the DNS query request, forward the DNS query request to SMF.
  • the SMF continues to perform other steps in the session establishment process, which is not related to the present invention, and will not be repeated here.
  • Step 1004 After the session is established, the UE sends a DNS query request to the core network according to its own business requirements, and initiates a DNS query for an application.
  • the DNS query request carries the domain name corresponding to the application.
  • the DNS query request of the UE is forwarded to the SMF.
  • Step 1005 If the SMF detects that the domain name requested by the UE is included in the application deployment location, domain name, and IP address correspondence obtained in step 1003, the DNAI is determined according to the current location (TAI) of the UE, and the IP address corresponding to the DNAI is determined; at the same time; The SMF determines that the IP address is an anycast address, and the application corresponding to the domain name requested by the UE is deployed on multiple MEC platforms, all using the anycast address.
  • TAI current location
  • Step 1006 SMF sets the TTL corresponding to the IP address to a relatively large value.
  • Step 1007 The SMF returns a DNS query response, and the DNS query response includes the IP address and TTL corresponding to the domain name requested by the UE.
  • SMF learns that the application corresponding to the domain name requested by the UE has anycast address on different MEC platforms.
  • SMF modifies the TTL in the DNS query response to a larger value, so that even before the TTL expires, the UE uses any The service can be accessed through the broadcast address, but UPF can access local applications nearby according to the anycast address.
  • the first network element when the first network element (UPF or DNS server) receives the UE’s DNS query request, the first network element may modify the first retention time to the second retention time. Time, and then send the second retention time to the UE.
  • steps 1003-step 1007 in the embodiment of FIG. 10 can be replaced with the following steps 1003' to 1006':
  • the SMF sends the first indication information to the UPF.
  • the first indication information is used to instruct the UPF to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform after receiving the DNS query request from the UE. If the application corresponding to the domain name requested by the UE is deployed on the MEC platform, then UPF needs to modify the TTL carried in the DNS response.
  • the first indication information further includes instructions for instructing the UPF to determine whether the IP address corresponding to the domain name requested by the UE is an anycast address after receiving the DNS query request response from the DNS server. If the IP address corresponding to the domain name requested by the UE is If the application corresponding to the anycast address and the domain name requested by the UE is deployed on the MEC platform, the UPF needs to modify the TTL carried in the DNS response.
  • the UE initiates a DNS query request according to the address of the DNS server obtained in step 1001.
  • the DNS query request carries the domain name requested by the UE, the source address (the IP address of the UE), the destination address (the address of the DNS server), and the UPF receives After the DNS query request to the UE, it is sent to the DNS server, and the DNS query response is received from the DNS server, which carries the IP address and the first TTL corresponding to the domain name of the application.
  • the first TTL is the retention time of the DNS cache record corresponding to the IP address determined by the DNS server.
  • step 1005' UPF judges that the application corresponding to the domain name requested by the UE is deployed on the MEC platform according to the first indication information sent by the SMF in step 1003', wherein the method for UPF to determine that the application corresponding to the domain name requested by the UE is deployed on the MEC platform can be Yes: UPF can store configuration information, the configuration information includes which domain names corresponding applications are deployed on the MEC platform, or UPF receives second indication information sent by SMF, the second indication information is used to indicate which domain names corresponding applications are deployed on the MEC platform , The present invention is not limited. UPF modifies the first TTL to the second TTL.
  • UPF determines, according to the first indication information sent by SMF in step 1003', that the application corresponding to the domain name requested by the UE is deployed on the MEC platform, and the IP address included in the DNS query response is an anycast address, and UPF sets the first TTL Modified to the second TTL.
  • the method for the UPF to determine the second TTL may be: a second threshold is configured on the UPF, and the second TTL is any value not less than the second threshold. Exemplarily, the second threshold may be 10 hours. It should be noted that the UPF also determines the second TTL according to other methods, which is not limited in the present invention.
  • Step 1006' the UPF sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • the solution of steps 1003-step 1007 in the embodiment of FIG. 10 can be replaced with the following steps 1003" to 1005":
  • Step 1003 the UE will initiate a DNS query request according to the address of the DNS server obtained in step 1001.
  • the DNS query request carries the domain name requested by the UE, the source address (the IP address of the UE), the destination address (the address of the DNS server), and the UPF receives After the DNS query request to the UE, it is sent to the DNS server.
  • Step 1004" the DNS server determines the IP address corresponding to the domain name of the application.
  • the DNS server determines whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform, and if the application corresponding to the domain name requested by the UE is deployed on the MEC platform, the first TTL is modified to the second TTL.
  • the method for the DNS server to determine whether the application corresponding to the domain name requested by the UE is deployed on the MEC platform may be: the DNS server can store configuration information, and the configuration information contains which domain names corresponding applications are deployed on the MEC platform, which is not limited by the present invention .
  • the DNS server can also determine whether the IP address corresponding to the domain name requested by the UE is an anycast address. If the application corresponding to the domain name requested by the UE is deployed on the MEC platform, and the IP address corresponding to the domain name of the application is an anycast address, Then the DNS server modifies the first TTL to the second TTL.
  • the method for the DNS server to determine the second TTL may be: a second threshold is configured on the DNS server, and the second TTL is any value not less than the second threshold. Exemplarily, the second threshold may be 10 hours. It should be noted that the DNS server also determines the second TTL according to other methods, which is not limited in the present invention.
  • Step 1005" the DNS server sends the second TTL and the IP address corresponding to the domain name to the UE through the DNS query response.
  • each network element described above includes hardware structures and/or software modules corresponding to each function.
  • the present invention can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software-driven hardware depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered as going beyond the scope of the present invention.
  • a device for implementing any of the above methods.
  • a device is provided that includes units (or means) for implementing each step performed by the terminal device in any of the above methods.
  • another device is also provided, including a unit (or means) for implementing each step performed by the session management network element in any of the above methods.
  • FIG. 11 is a schematic diagram of an apparatus for determining a DNS cache record provided by an embodiment of the application.
  • the device is used for terminal equipment.
  • the device 1100 includes a location determining unit 1110 and an updating unit 1120.
  • a receiving unit 1130 and a sending unit 1140 may also be included.
  • the location determining unit 1110 is used to determine that the data network access identifier DNAI has changed.
  • the update unit 1120 is configured to update DNS cache records.
  • the updated DNS cache records include at least one of the domain name of the application or the Internet Protocol IP address of the application server corresponding to the domain name, and the application server corresponds to the changed DNAI.
  • the receiving unit 1130 is configured to receive a DNAI change instruction; the position determining unit 1110 is specifically configured to determine that the DNAI has changed according to the DNAI change instruction.
  • the position determining unit 1110 is specifically configured to determine the DNAI corresponding to the position after the movement, and the DNAI corresponding to the position before the movement is different, to determine that the DNAI has changed.
  • the sending unit 1140 is configured to send an update cache request, where the update cache request includes the domain name of the application; the receiving unit 1130 is configured to receive an update cache response, where the update cache response includes all The IP address and the retention time, the retention time is the retention time of the DNS cache record corresponding to the IP address; the update unit 1120 is specifically configured to update the DNS cache record according to the IP address.
  • FIG. 12 is a schematic diagram of another apparatus for determining a DNS cache record provided by an embodiment of the application.
  • the device is used for a session management network element.
  • the device 1200 includes a location receiving unit 1210, a processing unit 1220, and a sending unit 1230.
  • the receiving unit 1210 is configured to receive a first DNS query request from a terminal device, where the first DNS query request includes a domain name and an address of a DNS server; the sending unit 1230 is configured to send a second DNS query request to the DNS server, The second DNS query request includes the domain name; the receiving unit 1210 is further configured to receive from the DNS server the IP address and first retention time of the first application server corresponding to the domain name, where the first retention time is The retention time of the DNS cache record corresponding to the IP address; the processing unit 1220 is configured to determine that the first condition is satisfied, and modify the first retention time to the second retention time; the sending unit 1230 is also configured to send The device sends the IP address and the second retention time, where the IP address and the second retention time are used by the terminal device to determine a DNS cache record corresponding to the IP address.
  • the first condition includes: the mobility attribute of the terminal device is high mobility.
  • the receiving unit 1210 is further configured to obtain the mobility attribute of the terminal device from a mobility management network element or a data management network element.
  • the first condition includes: the first mobile edge computing MEC platform where the first application server corresponding to the domain name is located and the second MEC platform where the second application server corresponding to the domain name is located Intercommunication cannot be achieved between them.
  • the second retention time is less than the first retention time, and the second retention time is equal to 0, or a positive number not greater than a preset first threshold.
  • the first condition includes: the IP address is an anycast address.
  • the second retention time is greater than the first retention time, and the second retention time is not less than a preset second threshold.
  • the first condition includes: the first application server corresponding to the domain name is deployed on the MEC platform.
  • each unit in the device can be all implemented in the form of software called by processing elements; they can also be all implemented in the form of hardware; part of the units can also be implemented in the form of software called by the processing elements, and some of the units can be implemented in the form of hardware.
  • each unit can be a separate processing element, or it can be integrated in a certain chip of the device for implementation.
  • it can also be stored in the memory in the form of a program, which is called and executed by a certain processing element of the device.
  • each step of the above method or each of the above units may be implemented by an integrated logic circuit of hardware in a processor element or implemented in a form of being called by software through a processing element.
  • the unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, for example: one or more application specific integrated circuits (ASICs), or, one or Multiple microprocessors (digital singnal processors, DSPs), or, one or more field programmable gate arrays (Field Programmable Gate Arrays, FPGAs), or a combination of at least two of these integrated circuits.
  • ASICs application specific integrated circuits
  • DSPs digital singnal processors
  • FPGAs Field Programmable Gate Arrays
  • the unit in the device can be implemented in the form of a processing element scheduler
  • the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call programs.
  • CPU central processing unit
  • these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).
  • the above receiving unit is an interface circuit of the device for receiving signals from other devices.
  • the receiving unit is an interface circuit used by the chip to receive signals from other chips or devices.
  • the above unit for sending is an interface circuit of the device for sending signals to other devices.
  • the sending unit is an interface circuit used by the chip to send signals to other chips or devices.
  • FIG. 13 is a schematic structural diagram of a terminal device according to an embodiment of the application.
  • the terminal device is used to implement the operation of the terminal device in the above embodiment.
  • the terminal equipment includes: an antenna 1310, a radio frequency device 1320, and a signal processing part 1330.
  • the antenna 1310 is connected to the radio frequency device 1320.
  • the radio frequency device 1320 receives the information sent by the access network device through the antenna 1310, and sends the information sent by the access network device to the signal processing part 1330 for processing.
  • the signal processing part 1330 processes the information of the terminal equipment and sends it to the radio frequency device 1320.
  • the radio frequency device 1320 processes the information of the terminal equipment and sends it to the access network equipment via the antenna 1310.
  • the signal processing part 1330 is used to realize the processing of each communication protocol layer of the data.
  • the signal processing part 1330 may be a subsystem of the terminal device, and the terminal device may also include other subsystems, such as a central processing subsystem, which is used to process the operating system and application layer of the terminal device; another example is the peripheral sub-system.
  • the system is used to realize the connection with other equipment.
  • the signal processing part 1330 may be a separately provided chip.
  • the above devices may be located in the signal processing part 1330.
  • the signal processing part 1330 may include one or more processing elements 1331, for example, a main control CPU and other integrated circuits.
  • the signal processing part 1330 may also include a storage element 1332 and an interface circuit 1333.
  • the storage element 1332 is used to store data and programs.
  • the program used to execute the method performed by the terminal device in the above method may or may not be stored in the storage element 1332, for example, stored in a memory other than the signal processing part 1330 During use, the signal processing part 1330 loads the program into the cache for use.
  • the interface circuit 1333 is used to communicate with the device.
  • the above device may be located in the signal processing part 1330, the signal processing part 1330 may be realized by a chip, the chip includes at least one processing element and an interface circuit, wherein the processing element is used to perform each step of any method executed by the above terminal device, the interface The circuit is used to communicate with other devices.
  • the unit that implements each step in the above method can be implemented in the form of a processing element scheduler.
  • the device includes a processing element and a storage element, and the processing element calls a program stored by the storage element to execute the above method embodiments.
  • the storage element may be a storage element whose processing element is on the same chip, that is, an on-chip storage element.
  • the program used to execute the method executed by the terminal device in the above method may be a storage element on a different chip from the processing element, that is, an off-chip storage element.
  • the processing element calls or loads a program from the off-chip storage element on the on-chip storage element to call and execute the method executed by the terminal device in the above method embodiment.
  • the unit of the terminal device that implements each step in the above method may be configured as one or more processing elements, and these processing elements are provided on the signal processing part 1330, where the processing elements may be integrated circuits, for example : One or more ASICs, or, one or more DSPs, or, one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits can be integrated together to form a chip.
  • the units that implement each step in the above method can be integrated together and implemented in the form of a system-on-a-chip (SOC), and the SOC chip is used to implement the above method.
  • SOC system-on-a-chip
  • the chip can integrate at least one processing element and a storage element, and the processing element can call the stored program of the storage element to implement the method executed by the above terminal device; or, the chip can integrate at least one integrated circuit to implement the above terminal The method executed by the device; or, it can be combined with the above implementations.
  • the functions of some units are implemented in the form of calling programs by processing elements, and the functions of some units are implemented in the form of integrated circuits.
  • the above apparatus may include at least one processing element and an interface circuit, wherein at least one processing element is used to execute any method executed by the terminal device provided in the above method embodiment.
  • the processing element can execute part or all of the steps executed by the terminal device in the first way: calling the program stored in the storage element; or in the second way: combining instructions through the integrated logic circuit of the hardware in the processor element Part or all of the steps executed by the terminal device are executed in a manner; of course, part or all of the steps executed by the terminal device may also be executed in combination with the first manner and the second manner.
  • the processing element here is the same as the above description, and it may be a general-purpose processor, such as a CPU, or one or more integrated circuits configured to implement the above method, such as: one or more ASICs, or, one or more micro-processing DSP, or, one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms.
  • the storage element can be a memory or a collective term for multiple storage elements.
  • FIG. 14 is a schematic structural diagram of a session management network element provided by an embodiment of this application, which is used to implement the operation of the session management network element in the above embodiment.
  • the session management network element includes: a processor 1410, a memory 1420, and an interface 1430, and the processor 1410, a memory 1420, and the interface 1430 are in signal connection.
  • the method executed by the session management network element in the above embodiment may be implemented by the processor 1410 calling a program stored in the memory 1420. That is, the apparatus for the session management network element includes a memory and a processor, and the memory is used to store a program, and the program is called by the processor to execute the method executed by the session management network element in the above method embodiment.
  • the processor here may be an integrated circuit with signal processing capability, such as a CPU.
  • the apparatus for the session management network element may be realized by one or more integrated circuits configured to implement the above method. For example: one or more ASICs, or, one or more microprocessors DSP, or, one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. Or, the above implementations can be combined.
  • the computer may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).
  • the various illustrative logic units and circuits described in the embodiments of this application can be implemented by general-purpose processors, digital signal processors, application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, Discrete gates or transistor logic, discrete hardware components, or any combination of the above are designed to implement or operate the described functions.
  • the general-purpose processor may be a microprocessor.
  • the general-purpose processor may also be any traditional processor, controller, microcontroller, or state machine.
  • the processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration. achieve.
  • the aforementioned functions described in this application can be implemented in hardware, software, firmware, or any combination of the three. If implemented in software, these functions can be stored on a computer-readable medium, or transmitted on the computer-readable medium in the form of one or more instructions or codes.
  • Computer-readable media include computer storage media and communication media that facilitate the transfer of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a general-purpose or special computer.
  • 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 program code media that can be read by general-purpose or special computers, or general-purpose or special processors.
  • any connection can be appropriately defined as a computer-readable medium, for example, if the software is from a website, server, or other remote source through a coaxial cable, fiber optic computer, twisted pair, or 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 said disks and discs include compressed disks, laser disks, optical discs, digital versatile discs (English: Digital Versatile Disc, abbreviated as: DVD), floppy disks and Blu-ray discs.
  • Disks usually copy data with magnetism.
  • Discs usually use lasers to copy data optically.
  • the combination of the above can also be contained in a computer readable medium.
  • the functions described in this application can be implemented by hardware, software, firmware, or any combination thereof. When implemented by software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on the computer-readable medium.
  • the computer-readable medium includes a computer storage medium and a communication medium, where the communication medium includes any medium that facilitates the transfer of a computer program from one place to another.
  • the storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

Abstract

本申请提供一种DNS缓存记录的确定方法及装置。该方法包括：终端设备确定DNAI发生改变。终端设备更新DNS缓存记录，更新后的DNS缓存记录至少包括应用的域名或所述域名对应的应用服务器的互联网协议IP地址的一种，所述IP地址与改变后的DNAI对应。基于该方案，终端设备确定DNAI发生改变后，获取新的DNS缓存记录，新的DNS缓存记录中包含的应用的域名对应的IP地址为改变后的DNAI对应的应用服务器的IP地址，即改变后的DNAI处部署的应用服务器的IP地址。从而后续终端设备将会通过新的IP地址访问应用，实现了就近访问业务。

Description

一种DNS缓存记录的确定方法及装置 技术领域
本申请涉及移动通信技术领域，尤其涉及一种DNS缓存记录的确定方法及装置。
背景技术
随着移动手机用户数量的不断增长，各类手机终端支持的业务功能不断增加，例如手机QQ、微信、飞信、手机证券、手机浏览、文件下载等功能已逐步成为手机终端，尤其是智能手机的主流应用。在上网过程中，手机需要对统一资源定位符(Uniform Resource Locator，URL)的域名查询其真实互联网协议(internet protocol，IP)地址，以便发送数据包。这项操作需要通过查询域名系统(Domain Name System，DNS)服务器才能完成。
域名系统是一种分布式的主机信息数据库，提供域名和互联网协议(Internet Protocol，IP)地址之间的映射和转换，可以通过DNS服务器将域名解析为对应的IP地址。终端设备可以通过DNS服务器提供的域名解析服务实现对域名的访问。
目前，域名访问的过程如下：以终端设备访问域名A为例，当终端设备访问该域名A时，查询终端设备的DNS缓存记录中是否存在该域名A对应的IP地址，如果存在，则终端设备可以直接获取该IP地址，然后通过该IP地址访问该域名A；如果不存在，则终端设备可以向DNS服务器发送域名解析请求，该域名解析请求携带该域名A，由DNS服务器返回该域名A对应的IP地址，然后终端设备可以通过该IP地址访问该域名A。
终端设备在获得域名对应的IP地址后，生成并缓存一条DNS缓存记录。该DNS缓存记录用于表示域名与IP地址的对应关系。此外，终端设备针对缓存的每条DNS缓存记录维护相应的存留时间(time to live，TTL)。
TTL表示IP地址对应的DNS缓存记录在终端设备的缓存中的存留或缓存的时间，其中0代表只能被传输，但是不能被缓存。这样，若在DNS缓存记录的TTL内，终端设备需要再次访问该DNS缓存记录中的相同域名时，则终端设备可以直接根据DNS缓存记录，获取域名对应的IP地址；若超过DNS缓存记录的TTL后，当终端设备需要再次访问该域名时，则终端设备需要通过上述过程，通过DNS服务器解析得到域名对应的IP地址。
对于具有移动性的终端设备，当终端设备在移动之前获得了某个域名对应的DNS缓存记录，若该DNS缓存记录的TTL在终端设备移动之后仍有效，终端设备可能由于DNS缓存没有更新或DNS缓存记录对应的存留时间不合适，导致无法在当前位置就近访问该域名对应的应用。因此基于该DNS缓存记录，如何实现终端设备就近访问IP地址对应的应用服务器中的应用，目前还没有很好的解决方案。
发明内容
本申请提供一种DNS缓存记录的确定方法及装置，用以实现终端设备就近访问IP地址对应的应用服务器中的应用。
第一方面，本申请提供一种DNS缓存记录的确定方法，包括：终端设备确定DNAI发生改变；所述终端设备更新DNS缓存记录，更新后的DNS缓存记录至少包括应用的域名或所述域名对应的应用服务器的互联网协议IP地址的一种，所述IP地址与改变后的 DNAI对应。基于该方案，终端设备确定DNAI发生改变后，获取新的DNS缓存记录，新的DNS缓存记录中包含的应用的域名对应的IP地址为改变后的DNAI对应的应用服务器的IP地址，即改变后的DNAI处部署的应用服务器的IP地址。从而后续终端设备将会通过新的IP地址访问应用，实现了就近访问业务。
在一种可能的实现方法中，所述终端设备确定DNAI发生改变，包括：所述终端设备接收DNAI改变指示，根据所述DNAI改变指示确定DNAI发生改变；或者，所述终端设备确定移动后所在的位置对应的DNAI，与移动前所在的位置对应的DNAI不同，则确定DNAI发生改变。
在一种可能的实现方法中，所述终端设备更新DNS缓存记录，包括：所述终端设备发送更新缓存请求，所述更新缓存请求包括所述应用的域名；所述终端设备接收更新缓存响应，所述更新缓存响应包括所述IP地址；所述终端设备根据所述IP地址，更新DNS缓存记录。
第二方面，本申请提供一种DNS缓存记录的确定方法，包括：核心网网元接收来自终端设备的第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址；所述核心网网元向所述DNS服务器发送第二DNS查询请求，所述第二DNS查询请求包含所述域名；所述核心网网元从所述DNS服务器接收所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间；所述核心网网元确定满足第一条件，将所述第一存留时间修改为第二存留时间；所述核心网网元向所述终端设备发送所述IP地址和所述第二存留时间，所述IP地址和所述第二存留时间用于所述终端设备确定所述IP地址对应的DNS缓存记录。基于该方案，核心网网元可以修改域名对应的IP地址对应的DNS缓存记录的存留时间，从而使得UE可以基于该修改后的存留时间来访问IP地址对应的应用服务器的应用，也即可以通过修改后的存留时间控制UE就近访问IP地址对应的应用服务器中的应用。
第三方面，本申请提供另一种DNS缓存记录的确定方法,包括：
DNS服务器接收来自终端设备的第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址；
所述DNS服务器确定所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间；
所述DNS服务器确定满足第一条件，将所述第一存留时间修改为第二存留时间；
所述DNS服务器向所述终端设备发送所述IP地址和所述第二存留时间，所述IP地址和所述第二存留时间用于所述终端设备确定所述IP地址对应的DNS缓存记录。
基于上述第二方面、或第三方面，还可以包括以下实施例：
其中第一条件包括但不限于：
方法一、所述第一条件包括：所述终端设备的移动性属性为高移动性。
在一种可能的实现方法中，所述会话管理网元从移动性管理网元或数据管理网元获取所述终端设备的移动性属性。
方法二、所述第一条件包括：所述域名对应的第一应用服务器所在的第一移动边缘计算MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通。
在一种可能的实现方法中，所述第二存留时间小于所述第一存留时间，所述第二存留时间等于0、或为不大于预设的第一阈值的正数。
方法三、所述第一条件包括：所述IP地址是一个任播地址。
在一种可能的实现方法中，所述第二存留时间大于所述第一存留时间，所述第二存留时间不小于预设的第二阈值。
方法四、第一条件包括：所述域名对应的第一应用服务器部署在MEC平台上。
方法五、所述第一条件包括：所述终端设备的移动性属性为高移动性、且所述域名对应的第一应用服务器部署在MEC平台上。
在一种可能的实现方法中，所述会话管理网元从移动性管理网元或数据管理网元获取所述终端设备的移动性属性。
方法六、所述第一条件包括：所述域名对应的第一应用服务器所在的第一MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通、且所述域名对应的第一应用服务器部署在MEC平台上。
在一种可能的实现方法中，所述第二存留时间小于所述第一存留时间，所述第二存留时间等于0、或为不大于预设的第一阈值的正数。
方法七、所述第一条件包括：所述IP地址是一个任播地址、且所述域名对应的第一应用服务器部署在MEC平台上。
在一种可能的实现方法中，所述第二存留时间大于所述第一存留时间，所述第二存留时间不小于预设的第二阈值。
第四方面，本申请提供一种DNS缓存记录的确定装置，该装置可以是终端设备，还可以是用于终端设备的芯片。该装置具有实现上述第一方面或第一方面的各实施例的功能。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，本申请提供一种DNS缓存记录的确定装置，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或第二方面的各实施例的功能。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。
第六方面，本申请提供一种DNS缓存记录的确定装置，该装置可以是DNS服务器，还可以是用于DNS服务器的芯片。该装置具有实现上述第三方面或第三方面的各实施例的功能。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。
第七方面，本申请提供一种DNS缓存记录的确定装置，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各方面所述的方法。该装置可以是终端设备、或用于终端设备的芯片、或会话管理网元、或用于会话管理网元的芯片、或DNS服务器、或用于DNS服务器的芯片。
第八方面，本申请提供一种DNS缓存记录的确定装置，包括：包括用于执行上述各方面的各个步骤的单元或手段(means)。该装置可以是会话管理网元、或终端设备、或DNS服务器。
第九方面，本申请提供一种DNS缓存记录的确定装置，包括处理器和接口电路，所述处理器用于通过接口电路实现上述各方面所述的方法。该处理器包括一个或多个。该装置可以是用于会话管理网元、或终端设备、或DNS服务器的芯片。
第十方面，本申请提供一种DNS缓存记录的确定装置，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，以执行上述各方面所述的方法。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。该装置可以是终端设备、或用于终端设备的芯片、或会话管理网元、或用于会话管理网元、或用于DNS服务器的芯片。
第十一方面，本申请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各方面所述的方法。
第十二方面，本申请还提供一种包括指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述各方面所述的方法。
第十三方面，本申请还提供一种芯片系统，包括：处理器，用于执行上述各方面所述的方法。
附图说明
图1为本申请适用的一种可能的网络架构示意图；
图2为本申请适用的又一种可能的网络架构示意图；
图3为域名解析场景示意图；
图4A为本申请提供的一种DNS缓存记录的确定方法流程示意图；
图4B为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图5为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图6为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图7为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图8为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图9为本申请提供的应用访问示意图；
图10为本申请提供的又一种DNS缓存记录的确定方法流程示意图；
图11为本申请提供的一种DNS缓存记录的确定装置示意图；
图12为本申请提供的又一种DNS缓存记录的确定装置示意图。
图13为本申请提供的一种终端设备示意图；
图14为本申请提供的一种会话管理网元示意图。
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。
如图1所示，为基于服务化架构的第五代(5th generation，5G)网络架构示意图。图1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：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)网元、网络存储功能(Network Repository Function，NRF) 网元、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、会话管理功能(session management function，SMF)网元、无线接入网(radioaccess network，RAN)、统一的数据存储库(Unified Data Repository，UDR)(图中未示出)、网络数据分析功能网元(Network Data Analytics Function，NWDAF)网元以及用户面功能(user plane function，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。
终端设备(terminal device)，也可以称为用户设备(user equipment，UE)，是一种具有无线收发功能的设备，可以部署在陆地上，包括室内或室外、手持或车载；也可以部署在水面上(如轮船等)；还可以部署在空中(例如飞机、气球和卫星上等)。所述终端设备可以是手机(mobile phone)、平板电脑(pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端、增强现实(augmented reality，AR)终端、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。
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，移动性管理功能，负责用户的移动性管理，包括移动状态管理，分配用户临时身份标识，认证和授权用户。
SMF网元，会话管理功能，负责UPF选择，UPF重选，IP地址分配，负责承载的建立、修改和释放，QoS控制。
UPF网元，支持以下全部或者部分功能：将协议数据单元(protocol data unit，PDU)会话与数据网络互连；分组路由和转发(例如，支持对流量进行Uplink classifier后转发到数据网络，支持Branching point以支持multi-homed PDU会话)；数据包检测。
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。
UDM网元，负责管理签约数据，当签约数据修改的时候，负责通知相应的网元。
UDR，用于存储和检索签约数据、策略数据和公共架构数据等；供UDM、PCF和NEF获取相关数据。UDR要能够针对不同类型的数据如签约数据、策略数据有不同的数据接入鉴权机制，以保证数据接入的安全性；UDR对于非法的服务化操作或者数据接入请求要能够返回携带合适原因值的失败响应。
NEF网元，主要用于支持能力和事件的开放。
AF网元，向UE提供某种应用层服务，AF在向UE提供服务时，对QoS策略和计费策略(Charging)有要求，且需要通知网络。同时，AF也需要核心网反馈的应用相关的信息。
PCF网元，包含策略控制决策和基于流计费控制的功能，包含用户签约数据管理功能，策略控制功能，计费策略控制功能，QoS控制等。
NRF网元，可用于提供网元发现功能，基于其他网元的请求，提供网元类型对应的网元信息。NRF还提供网元管理服务，如网元注册、更新、去注册以及网元状态订阅和推送等。
NWDAF网元，用于根据策略模块PCF请求，提供签约终端的大数据分析信息，帮助PCF优化策略控制；可按照切片维度提供大数据分析信息。
图1中Nnef、Nnrf、Npcf、Nudm、Nnwdaf、Naf、Nausf、Namf、Nsmf、N1、N2、N3、N4，以及N6为接口序列号。这些接口序列号的含义可参见第三代合作伙伴计划(3rd generation partnership project，3GPP)标准协议中定义的含义，在此不做限制。
如图2所示，为基于点对点接口的5G网络架构示意图，其中的网元的功能的介绍可以参考图1中对应的网元的功能的介绍，不再赘述。图2与图1的主要区别在于：图2中的各个网元之间的接口是点对点的接口，而不是服务化的接口。需要说明的是，图2中还包括其他网元，如NEF网元、NRF网元、UDR、NWDAF网元等，图2中未示出。
在图2所示的架构中，其中，UE与AMF网元之间的接口称为N1接口，AMF网元与RAN设备之间的接口称为N2接口，RAN设备与UPF网元之间的接口可以称为N3接口，SMF网元与UPF网元之间的接口称为N4接口，PCF网元与AF网元之间的接口称为N5接口，UPF网元与DN之间的接口称为N6接口，SMF网元与PCF网元之间的接口称为N7接口，AMF网元与UDM网元之间的接口称为N8接口，不同UPF网元之间的接口称为N9接口，UDM网元与SMF网元之间的接口称为N10接口，AMF网元与SMF网元之间的接口称为N11接口，不同AMF网元之间的接口称为N14接口，AMF网元与PCF网元之间的接口称为N15接口。
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。
本申请中的移动性管理网元、会话管理网元、策略控制网元、应用功能网元、接入网设备、网络开放功能网元、用户面网元分别可以是图1或图2中的AMF、SMF、PCF、AF、RAN、NEF、UPF，也可以是未来通信如第六代(6th generation，6G)网络中具有上述AMF、 SMF、PCF、AF、RAN、NEF、UPF的功能的网元，本申请对此不限定。为方便说明，本申请以移动性管理网元、会话管理网元、策略控制网元、应用功能网元、接入网设备、网络开放功能网元、用户面网元分别为上述AMF、SMF、PCF、AF、RAN、NEF、UPF为例进行说明。并且，本申请中将终端设备简称为UE。
如图3所示，根据3GPP TS 23.501，UE在初始会话建立流程中，SMF会给UE发送一个DNS服务器的地址；之后，UE会使用该DNS服务器的地址进行域名查询。
根据TS 23.501，当UE移动到移动边缘计算(Mobile Edge Compute，MEC)平台-1所在位置，SMF根据当前位置的数据网络接入标识(data network access identifier，DNAI)插入分流点(上行分类器(Uplink Classifier，UL CL)或分支点(Branching point，BP))，实现本地业务访问，即业务流可以直接分流到MEC平台上。如果UE请求访问该MEC平台(如MEC平台1)上的某个应用(假设该应用为应用-1，域名：域名A)，则需要先查询该应用的域名A对应的IP地址，域名A对应的IP地址即为域名A对应的应用服务器的IP地址。UE向DNS服务器发送域名A，DNS服务器根据UE当前的位置将域名A解析为IP-1，其中，UE当前的位置可以是MEC平台1的标识(用DNAI来表示)，本发明不做限定，同时DNS服务器返回TTL给UE，UE使用IP-1与该应用进行通信，这条记录(记录包括：域名A对应的IP-1以及TTL)会保留在UE的缓存中。
当UE发生移动切换到另一个MEC平台(如MEC平台2)，如果UE仍然要访问应用-1(应用-1的域名是域名A不变)，当UE侧的DNS缓存记录中的TTL未超时，UE根据缓存记录仍然查询到域名A对应IP-1，UE继续使用IP-1访问业务，但是UE当前所在位置所在的MEC平台上可能会部署了域名A的另一个应用服务器(假设该应用服务器的IP地址为IP-2)，因此IP-2离UE更近，因此UE使用IP-1访问应用的话，会导致业务访问路径不优化。
针对该移动场景下UE发生MEC平台的切换，UE侧如何触发DNS缓存更新，才能保证UE可以访问当前所在位置所在的MEC平台部署的应用，是本申请要解决的问题。
为解决上述问题，基于图1或图2所示的架构，本申请提供一种DNS缓存记录的确定方法，如图4A所示，该方法包括以下步骤：
步骤401a，UE确定DNAI发生改变。
步骤402b，UE更新DNS缓存记录，更新后的DNS缓存记录至少包括应用的域名或所述域名对应的应用服务器的互联网协议IP地址的一种，所述IP地址与改变后的DNAI对应。
其中，一条DNS缓存记录中至少包括域名或域名对应的IP地址，该IP地址为应用服务器的IP地址。该步骤402b中，UE更新DNS缓存记录的方法包括但不限于：
方法一、替换原DNS缓存记录中的部分信息。
比如，原DNS缓存记录包括域名A和IP地址1，然后将原DNS缓存记录中的IP地址1替换为IP地址2，但域名A保持不变，因而更新后的DNS缓存记录包括域名A和IP地址2。
方法二、删除原DNS缓存记录，新增一条新的DNS缓存记录
比如，原DNS缓存记录包括域名A和IP地址1，则先删除原DNS缓存记录，然后生 成一条新的DNS缓存记录，该新的DNS缓存记录包括域名A和IP地址2。
基于该方案，终端设备确定DNAI发生改变后，获取新的DNS缓存记录，新的DNS缓存记录中包含的应用的域名对应的IP地址为改变后的DNAI对应的应用服务器的IP地址，即改变后的DNAI处部署的应用服务器的IP地址。从而后续终端设备将会通过新的IP地址访问应用，实现了就近访问业务。
上述步骤401a中，UE确定DNAI发生改变的方法包括但不限于以下两种方法。
方法一，UE接收DNAI改变指示，根据DNAI改变指示确定DNAI发生改变。
比如，SMF获取到UE移动之前的位置信息对应的DNAI-1，以及获取到UE移动之后的位置信息对应的DNAI-2，若DNAI-2与DNAI-1不同，则SMF生成DNAI改变指示，然后SMF通过AMF，向UE发送该DNAI改变指示，以通知UE：DNAI发生改变。其中，DNAI-1和DNAI-2分别标识两个不同的MEC平台。
方法二，UE确定移动后所在的位置对应的DNAI，与移动前所在的位置对应的DNAI不同，则确定DNAI发生改变。
比如，在UE的注册流程中，AMF将为该UE分配注册区域(registration area),其中，注册区域包含TAI列表，AMF将注册区域包含的TAI以及该TAI对应的DNAI发送至UE，UE存储TAI与DNAI的对应关系。作为一个示例，UE中存储的TAI与DNAI的对应关系如表1所示，UE的注册区域包含TAI-1、TAI-2、TAI-3、TAI-4、TAI-5和TAI-6，其中，TAI-1、TAI-2和TAI-3分别对应的DNAI为DNAI-1，TAI-4、TAI-5和TAI-6分别对应的DNAI为DNAI-2。
表1
注册区域包含的TAI DNAI
TAI-1、TAI-2、TAI-3 DNAI-1
TAI-4、TAI-5、TAI-6 DNAI-2
比如，UE移动前，UE所在的位置对应的TAI为TAI-1，对应DNAI-1；UE移动后，UE所在的位置对应的TAI为TAI-5，对应DNAI-2，且UE确定DNAI-2与DNAI-1不同，则UE确定DNAI发生改变。作为一种实现方法，上述步骤402a中UE更新DNS缓存记录的方法可以是：UE向网络侧发送更新缓存请求，所述更新缓存请求包括所述应用的域名；然后UE从网络侧接收到更新缓存响应，所述更新缓存响应包括IP地址。可选的，更新缓存响应中还可以包括存留时间，所述存留时间为所述IP地址对应的DNS缓存记录的存留时间，然后UE更新该IP地址更新DNS缓存记录，该IP地址为应用服务器的IP地址，该应用服务器的IP地址与改变后的DNAI对应。其中，上述更新缓存请求也可以是DNS查询请求或者其他消息名称的请求，上述更新缓存响应也可以是DNS查询响应或者其他消息名称的响应，本发明不做限定。
为解决上述问题，基于图1或图2所示的架构，本申请提供又一种DNS缓存记录的确定方法，如图4B所示，该方法包括以下步骤：
步骤401b，UE向核心网网元发送第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址。相应地，核心网网元可以接收到该第一DNS查询请求。
这里的核心网网元可以是UPF或SMF等。
步骤402b，核心网网元向DNS服务器发送第二DNS查询请求，所述第一DNS查询请求包含域名。相应地，DNS服务器可以接收到该第二DNS查询请求。
这里，核心网网元可以基于第一DNS查询请求中的DNS服务器的地址，向该DNS服务器发送第二DNS查询请求。
步骤403b，核心网网元从DNS服务器接收所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间。
DNS服务器接收到第二DNS查询请求，获取其中的域名，并将域名解析为IP地址。具体的，解析为域名对应的第一应用服务器的IP地址。然后DNS服务器向核心网网元发送域名对应的第一应用服务器的IP地址和第一存留时间。
步骤404b，核心网网元确定满足第一条件，将所述第一存留时间修改为第二存留时间。
步骤405b，核心网网元向UE发送所述域名对应的IP地址和第二存留时间。相应地，UE可以接收到所述域名对应的IP地址和第二存留时间。
UE接收到所述域名对应的IP地址和第二存留时间后，可以确定所述IP地址对应的DNS缓存记录。
基于该方案，核心网网元可以修改域名对应的IP地址对应的DNS缓存记录的存留时间，从而使得UE可以基于该修改后的存留时间来访问IP地址对应的应用服务器的应用，也即可以通过修改后的存留时间控制UE就近访问IP地址对应的应用服务器中的应用。
针对上述步骤404b，下面给出三种不同的实现方法。
实现方法一，第一条件包括：UE的移动性属性为高移动性。
也即，当核心网网元确定UE的移动性属性为高移动性(即UE移动频率超过某个阈值，或者UE移动速度超过某个阈值)，则将第一存留时间修改为第二存留时间，并且，这里的第二存留时间小于所述第一存留时间。具体的，第二存留时间等于0、或为不大于预设的第一阈值的正数，这里的第一阈值是一个比较小的正数。由于第二存留时间较小，甚至接近0，从而UE收到域名对应的应用服务器的IP地址之后，UE可能不保存DNS缓存记录(当第二存留时间等于0时)或者UE保存的DNS缓存记录很快失效(当第二存留时间为小于预设阈值的正数)，UE如需再次访问域名对应的应用，将不会从本地获取域名对应的IP地址，而是触发UE重新向DNS服务器发送域名，以获取域名对应的IP地址，进而DNS服务器可以将该域名对应的距离UE最近的应用服务器的IP地址发送给UE，以实现UE就近访问域名对应的应用服务器的应用。
可选的，核心网网元可以从AMF或NWDAF获取所述UE的移动性属性。
实现方法二，第一条件包括：域名对应的第一应用服务器所在的第一MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通。
这里的第一MEC平台为UE移动后所在位置对应的MEC平台，第二MEC平台为UE移动前所在位置对应的MEC平台。当第一MEC平台与第二MEC平台之间无法互通时，则当UE移动至新的位置后，无法通过第一MEC平台访问第二MEC平台位置处的应用服务器的应用。因此，该情形下，当UE请求获取第二MEC平台的应用服务器的IP地址时，核心网网元可以将第一存留时间修改为第二存留时间，且第二存留时间小于第一存留时间，第二存留时间等于0、或为不大于预设的第一阈值的正数，这里的第一阈值是一个比较小的正数。从而UE收到域名对应的应用服务器的IP地址之后，UE可能不保存DNS缓存记录(当第二存留时间等于0时)或者UE保存的DNS缓存记录很快失效(当第二存留时间 为不大于预设的第一阈值的正数)，UE如需再次访问域名对应的应用，将不会从本地获取域名对应的IP地址，而是触发UE重新向DNS服务器发送域名，以获取域名对应的IP地址，进而DNS服务器可以将该域名对应的距离UE最近的应用服务器的IP地址发送给UE，以UE实现就近访问域名对应的应用服务器的应用(即第一MEC平台位置处的应用服务器的应用)。
实现方法三，第一条件包括：UE请求的域名对应的IP地址是一个任播地址。
如果相同域名的应用在不同MEC平台上部署，且该应用的IP地址是任播地址的话(任播(Anycast)的定义是：当一个单播地址被分配到多于一个的接口上时，发到该接口的报文被网络路由到由路由协议度量的“最近”的目标接口上)，那么说明该应用的数据报文在核心网进行路由时，UPF会选择最近的应用服务器来实现路由，这种情况下，即便UE切换到另一个MEC平台上，且TTL没有超时，UE采用应用服务器的任播地址进行业务访问，UPF根据任播地址仍然可以将该数据报文路由到新的MEC平台上，因为新的MEC平台距离UPF更近一些。
该情形下，由于UE基于该任播地址，始终会就近访问MEC平台的应用服务器的应用，因此该情形下，可选的，核心网网元可以将第一存留时间修改为第二存留时间，且第二存留时间大于第一存留时间，第二存留时间不小于预设的第二阈值，这里的第二阈值是一个比较大的正数。即将IP地址对应的DNS缓存记录的存留时间修改为一个较大的值(该值即为第二存留时间)，使得UE可以根据DNS缓存记录的IP地址(即任播地址)就可以实现就近访问MEC平台的应用服务器的应用。
需要说明的是，在又一种实现方式中，核心网网元也可以不修改存留时间，即核心网网元接收到第一存留时间，则将第一存留时间发送至UE。从而如果第一存留时间超时后，UE通过DNS查询的方式获取到IP地址对应的应用服务器，此时由于IP地址是任播地址，因此仍然可以访问到就近的应用服务器中的应用。
实现方法四、第一条件包括：所述域名对应的第一应用服务器部署在MEC平台上。
实现方法五、所述第一条件包括：所述终端设备的移动性属性为高移动性、且所述域名对应的第一应用服务器部署在MEC平台上。
该方法是上述实现方法一与实现方法四的结合，具体可以参考上述实现方法一和实现方法四的描述，这里不再赘述。
实现方法六、所述第一条件包括：所述域名对应的第一应用服务器所在的第一MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通、且所述域名对应的第一应用服务器部署在MEC平台上。
该方法是上述实现方法二与实现方法四的结合，具体可以参考上述实现方法二和实现方法四的描述，这里不再赘述。
实现方法七、所述第一条件包括：所述IP地址是一个任播地址、且所述域名对应的第一应用服务器部署在MEC平台上。
该方法是上述实现方法三与实现方法四的结合，具体可以参考上述实现方法三和实现方法四的描述，这里不再赘述。
需要说明的是，作为图4b所示实施例的一种扩展方案，核心网网元也可以将UE的移动性属性、或域名对应的应用服务器所在的MEC平台的信息、或IP地址是否为任播地址等信息发送给DNS服务器等，由DNS服务器判断是否满足第一条件，当满足第一条件时， 则DNS服务器将第一存留时间修改为第二存留时间，然后将第二存留时间发送至UE。
需要说明的是，作为图4b所示实施例的又一种扩展方案，核心网网元在确定满足上述第一条件时，向DNS服务器等发送指示信息，用于指示DNS服务器将第一存留时间修改为第二存留时间，然后将第二存留时间发送至UE。
下面结合具体实施例，对上述图4A至图4B所示的实施例进行介绍说明。
如图5所示，为本申请提供的又一种DNS缓存记录的确定方法流程示意图。该实施例是上述图4A所示实施例的一种具体实现。
该实施例主要发明点如下：SMF根据UE当前位置对应的DNAI判断出UE从第一DNAI移动到第二DNAI，即UE的移动性导致发生了DNAI改变，则SMF通知UE发生了DNAI改变(通过N1 SM container下发给UE)，UE收到DNAI改变指示后，删除DNS缓存记录，并进行DNS缓存更新。
该方法包括以下步骤：
步骤501，网络中的DNS服务器存储应用的部署位置(应用的部署位置用DNAI来标识)、该应用对应的域名、该域名对应的IP地址之间的对应关系。
这里的DNS服务器可以是运营商部署的集中式DNS(例如，图5中与UPF-1连接的远端(remote)DNS服务器)，也可以是MEC平台上部署的本地DNS服务器。
步骤502，PDU会话建立流程。
UE发起会话建立流程，携带PDU会话标识(PDU Session ID)，单网络切片选择辅助信息(single network slice selection assistance information，S-NSSAI)和数据网名称(Data Network Name，DNN)等参数；AMF根据S-NSSAI和DNN选择SMF，并将该UE的永久标识，UE的位置信息(用跟踪区标识(Tracking area identity，TAI)来表示UE的位置信息)，PDU会话标识，S-NSSAI和DNN等参数发送给SMF，SMF为该UE选择UPF作为该会话的协议数据单元锚点(PDU Session Anchor，PSA)，该UPF即为图5中的PSA-1。
步骤503，SMF调用AMF的服务化操作Namf_Communication_N1N2MessageTransfer，携带PDU会话标识,N1 SM容器(N1 SM container)。其中N1 SM container中包含了DNS服务器的地址，该DNS服务器的地址即为图中的远端DNS服务器的地址。AMF通过RAN向UE发送非接入层(non access stratum，NAS)消息，携带PDU会话标识,N1 SM container，将SMF发送的DNS服务器的地址通过N1 SM container发送至UE。
步骤504，UE发生了移动并移动到了MEC平台的部署位置，假设当前位置为MEC平台-1的部署位置，SMF从AMF获取UE的位置信息，根据当前UE所在的TAI确定DNAI-1，其中，DNAI-1可以用来标识MEC平台-1。同时SMF决定为当前会话选择分流点UPF以及新的用户面锚点PSA-2，从而实现本地分流。这里的分流点UPF可以是上行分类器(Uplink Classifier，UL CL)或者分支点(Branching point，BP)，新的用户面锚点PSA-2与MEC平台-1可以进行数据传输。
步骤505，SMF向分流点UPF(即UL CL或BP)发送N4会话，该N4会话包括转发规则，该转发规则用于指示分流点UPF执行以下动作：
1)将收到来自UE的DNS查询请求中的目的地址替换为位于MEC平台-1上的DNS服务器的地址；
2)将来自UE的DNS查询请求发送至PSA-2。
步骤506，由于UE在步骤503中已经获取了DNS服务器的地址，如果UE需要访问某个应用，则UE会根据该DNS服务器的地址发起DNS查询请求，DNS查询请求中的源地址是UE的IP地址，目的地址是远端DNS服务器的地址，分流点UPF收到UE的DNS查询请求后，根据步骤505中SMF发送的转发规则，将DNS查询请求中的目的地址由远端DNS服务器的地址替换为位于MEC平台-1上的DNS服务器的地址。同时，分流点UPF将该DNS查询请求发送至PSA-2。PSA-2根据目的地址(即MEC平台-1上的DNS服务器的地址)寻址到DNS服务器，并接收DNS查询响应，PSA-2将DNS查询响应通过分流点UPF发送至UE，该DNS查询响应中携带应用的IP地址和TTL，该应用的IP地址为域名对应的MEC平台-1上的应用服务器的IP地址。
可选的，在步骤506中，分流点UPF或者PSA-2收到来自UE的DNS查询请求后，将本次DNS查询请求中包含的域名上报给SMF。如果UE在MEC平台-1发起了多个域名对应的DNS查询请求，那么分流点UPF或者PSA-2可以分别将多个域名上报给SMF。
步骤507，UE发生了移动并移动到了另一个MEC平台的部署位置，假设当前位置为MEC平台-2的部署位置，SMF从AMF获取UE的位置信息，根据当前UE所在的TAI确定DNAI-2。其中，DNAI-2可以用来标识MEC平台-2。至此，SMF获知UE从DNAI-1移动到了DNAI-2，即UE从MEC平台-1移动到了MEC平台-2。
步骤508，UL CL/BP以及本地PSA-3的插入。
SMF判断由于UE的移动性发生了DNAI改变，决定为当前会话选择新的分流点UPF以及新的用户面锚点PSA-3，从而实现本地分流。这里的分流点UPF可以是ULCL或者BP，新的用户面锚点PSA-3与MEC平台-2可以进行数据传输。
步骤509，SMF向新的分流点UPF发送转发规则，该转发规则用于指示新的分流点UPF执行以下动作：
1)将收到来自UE的DNS查询请求中的目的地址替换为位于MEC平台-2上的DNS服务器的地址；
2)将来自UE的DNS查询请求发送至PSA-3。
步骤510，SMF调用AMF的服务化操作Namf_Communication_N1N2MessageTransfer，携带PDU Session ID,N1 SM container。其中N1 SM container中包含了DNAI改变指示(DNAI change indication)。
步骤511，AMF通过RAN向UE发送NAS消息，携带PDU Session ID,N1 SM container，将SMF发送的DNAI改变指示通过N1 SM container发送至UE。
步骤512，UE通过NAS消息中的N1 SM container包含的DNAI改变指示，获知发生了DNAI改变，则UE删除DNS缓存记录。其中，UE删除DNS缓存记录可以理解为UE根据DNAI改变指示，删除所有域名对应的DNS缓存记录。
可选的，在步骤506中，如果SMF收到了UE在MEC平台-1请求的域名记录，在步骤510中，SMF可以将DNAI改变指示以及上述域名记录(可能UE查询了多个域名)通过N1 SM container发送至UE。这样UE就可以根据接收的域名记录包含的域名以及DNAI改变指示只删除包含在N1 SM container的域名对应的缓存记录。对于未包含在N1 SM container的域名，UE可以不删除该域名对应的缓存记录，即UE可以继续使用缓存记录里面包含的应用的域名对应的IP地址来访问该应用。
步骤513，UE发起缓存更新请求，携带域名，源地址(UE的IP地址)以及目的地址 (远端DNS服务器的地址)。其中，更新缓存请求也可以是DNS查询请求或者其他消息名称的请求，本发明不做限定。以UE发起DNS查询请求为例说明，分流点UPF收到UE的DNS查询请求后，根据步骤509中SMF发送的转发规则，将DNS查询请求中的目的地址由远端DNS服务器的地址替换为位于MEC平台-2上的DNS服务器的地址。同时，分流点UPF将该DNS查询请求发送至PSA-3。PSA-3根据目的地址(MEC平台-2上的DNS服务器的地址)寻址到该DNS服务器。
步骤514，DNS服务器发送更新缓存响应并通过PSA-3发送至UE。其中，更新缓存响应也可以是DNS查询响应或者其他消息名称的响应，本发明不做限定。以DNS服务器发送DNS查询响应为例说明，PSA-3接收DNS查询响应后，PSA-3将DNS查询响应通过分流点UPF发送至UE。该DNS查询响应包括应用的IP地址和TTL，该应用的IP地址为域名对应的MEC平台-2上的应用服务器的IP地址。
基于该实施例，UE根据DNAI改变指示执行DNS缓存更新，可以保证UE发生移动之后，都能做到就近访问本地应用，提高通信效率。
如图6所示，为本申请提供的又一种DNS缓存记录的确定方法流程示意图。该实施例是上述图4A所示实施例的一种具体实现。
该实施例方案概述如下：AMF存储该AMF的服务区域下面所有TAI与DNAI的对应关系(全集)。在注册流程中，AMF为UE分配注册区域(TAI list)，同时将UE注册区域对应的TAI list与DNAI的对应关系(子集)下发至UE。UE根据当前的TAI判断出DNAI，当UE发生了移动，如果new TAI对应new DNAI，则删除DNS缓存记录，并发起DNS缓存记录更新。
该方法包括以下步骤：
步骤600，网络中的DNS存储应用的部署位置(应用的部署位置用DNAI来标识)、该应用对应的域名、该域名对应的IP地址之间的对应关系。这里的DNS可以是运营商部署的集中式DNS服务器(图中的远端DNS服务器)，也可以是MEC平台上部署的本地DNS服务器。
此外，AMF存储该AMF的服务区域下面所有TAI跟DNAI的对应关系。
步骤601，UE发起注册流程，RAN将UE的注册请求消息发送至AMF网元。
步骤602，AMF网元为UE分配注册区域(Registration Area)，其中，Registration Area由TAI列表(TAI list)组成，同时，AMF根据存储的TAI与DNAI的对应关系以及Registration Area，确定Registration Area中的TAI与DNAI的对应关系。该步骤的具体描述可以参考步骤401a中的方法二。步骤603，AMF向UE发送注册接受消息，同时将Registration Area中的TAI与DNAI的对应关系通过注册接受消息发送至UE。
可选的，AMF还可以向UE发送指示信息，用于指示UE哪些DNAI的位置部署了MEC平台。也即，该指示信息用于指示部署的MEC平台对应的DNAI。
步骤604，UE发起会话建立流程，携带PDU会话标识，S-NSSAI和DNN等参数；AMF根据S-NSSAI和DNN选择SMF，并将该UE的永久标识，UE的位置信息(用TAI来表示UE的位置信息)，PDU会话标识，S-NSSAI和DNN等参数发送给SMF，SMF为该UE选择UPF作为该会话的PSA，该UPF即为图6中的PSA-1。
步骤605，SMF调用AMF的服务化操作Namf_Communication_N1N2MessageTransfer， 携带PDU会话标识,N1 SM container。其中N1 SM container中包含了DNS服务器的地址。该DNS服务器的地址即为图中的远端DNS服务器的地址。AMF通过RAN向UE发送NAS消息，携带PDU会话标识,N1 SM container，将SMF发送的DNS服务器的地址通过N1 SM container发送至UE。
步骤606至步骤609，同图5实施例的步骤504至步骤506。
步骤610，SMF从AMF获取UE的位置信息，根据UE当前位置确定DNAI-2。ULCL/BP以及本地PSA-3的插入。
UE发生了移动并移动到了另一个MEC平台的部署位置，假设当前位置为MEC平台-2的部署位置。SMF从AMF获取UE的位置信息，根据UE当前位置确定DNAI-2。SMF判断由于UE的移动性发生了DNAI改变，决定为当前会话选择新的分流点UPF以及新的用户面锚点PSA-3，从而实现本地分流。这里的分流点UPF可以是ULCL或者BP，新的用户面锚点PSA-3与MEC平台-2可以进行数据传输。
同时，SMF向新的分流点UPF发送转发规则，该转发规则用于指示新的分流点UPF执行以下动作：
1)将收到来自UE的DNS查询请求中的目的地址替换为位于MEC平台-2上的DNS服务器的地址。
2)将来自UE的DNS查询请求发送至PSA-3。
步骤611，UE根据当前所在的TAI判断DNAI，如果UE发现由于UE的移动导致DNAI改变，例如UE从第一TAI移动到第二TAI，第一TAI对应第一DNAI(例如DNAI1)，第二TAI对应第二DNAI(例如DNAI2)，那么就说明UE移动导致DNAI改变。
步骤612，UE获知发生了DNAI改变，则UE删除DNS缓存记录。其中，UE删除DNS缓存记录可以理解为UE根据DNAI改变指示，删除所有域名对应的DNS缓存记录。
步骤613，UE发起缓存更新请求，携带域名，源地址(UE的IP地址)以及目的地址(远端DNS服务器的地址)，其中，更新缓存请求也可以是DNS查询请求或者其他消息名称的请求，本发明不做限定。以UE发起DNS查询请求为例说明，分流点UPF收到UE的DNS查询请求后，根据步骤610中SMF发送的转发规则，将DNS查询请求中的目的地址由远端DNS服务器的地址替换为位于MEC平台-2上的DNS服务器的地址。同时，分流点UPF将该DNS查询请求发送至PSA-3。PSA-3根据目的地址(MEC平台-2上的DNS服务器的地址)寻址到该DNS服务器。DNS服务器发送更新缓存响应并通过PSA-3发送至UE。其中，更新缓存响应也可以是DNS查询响应或者其他消息名称的响应，本发明不做限定。以DNS服务器发送DNS查询响应为例说明，PSA-3接收DNS查询响应，PSA-3将DNS查询响应通过分流点UPF发送至UE。该DNS查询响应包括应用的IP地址和TTL，该应用的IP地址为域名对应的MEC平台-2上的应用服务器的IP地址。
基于该实施例，UE感知TAI和DNAI(MEC平台)的关系，当UE切换DNAI后，删除DNS记录，并发起DNS缓存更新。
如图7所示，为本申请提供的又一种DNS缓存记录的确定方法流程示意图。该实施例是上述图4B所示实施例的一种具体实现。
该实施例方案概述如下：如果UE签约了某些部署在MEC平台上的应用，这些应用的部署位置可以用DNAI来标识，即UE签约了某些部署在特定DNAI位置的应用，SMF 根据UE的移动性属性(例如SMF从AMF/NWDAF获取UE的移动性属性(mobility pattern))，对于高移动性UE(这种UE比较容易频繁切换MEC平台)，SMF解析DNS消息，如果UE请求了MEC平台上部署的应用对应的域名，SMF对DNS查询响应中的TTL进行修改，例如设置为0或者较小的数值，这样UE每次都会重新向DNS服务器发起域名解析的请求，因而可以保证UE每次进行业务访问的时候，都能访问到当前位置对应的本地应用。该方法包括以下步骤：
步骤701，UE发起会话建立流程，携带PDU会话标识，S-NSSAI和DNN等参数；AMF根据S-NSSAI和DNN选择SMF，并将该UE的永久标识，UE的位置信息(用TAI来表示UE的位置信息)，PDU会话标识，S-NSSAI和DNN等参数发送给SMF，SMF为该UE选择UPF作为该会话的PSA。
在该步骤中，SMF将DNS服务器的地址发送至UE，发送方法参考图5或图6实施例。
步骤702，可选的，SMF获取该UE的移动性属性。
SMF从PCF获取该UE签约的应用类型，以及应用对应的部署位置DNAI。如果该UE签约了MEC平台上部署的应用(这些应用部署位置对应的DNAI是特殊的DNAI)，则SMF触发获取该UE的移动性属性。
SMF获取该UE的移动性属性有两种实现方法：
实现方法一：SMF调用AMF网元的服务化操作Namf_EventExposure_Subscribe，携带UE的永久签约标识(Subscription Permanent Identifier，SUPI)，请求从AMF获取该UE的移动性属性。AMF返回Namf_EventExposure_Notify，包含UE的SUPI以及移动性属性。
实现方法二：SMF调用服务化操作Nnwdaf_AnalyticsSubscription_Subscribe，携带UE的SUPI，请求从NWDAF获取该UE的移动性属性。NWDAF对该UE进行数据收集后，进行大数据分析，得出该UE的移动性属性后，NWDAF向SMF返回Nnwdaf_AnalyticsSubscription_Notify，携带UE的SUPI以及移动性属性。
其中，移动性属性可以标识UE的移动性属性，例如移动性为高，移动性为中，移动性为低。
步骤703，SMF向UPF发梢N4回话，该N4回话包括DNS查询请求的转发规则。
具体的，SMF向该UE的会话对应的UPF发送转发规则，该转发规则用于指示UPF收到来自UE的DNS查询请求后，将该DNS查询请求转发给SMF处理。
步骤704，UE会根据步骤701获取的DNS服务器的地址发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，根据步骤703中SMF发送的转发规则将DNS查询请求发送给SMF处理。SMF将查询请求发送至DNS服务器，并从DNS服务器接收到DNS查询响应，其中携带应用的域名对应的IP地址和第一TTL。其中，第一TTL为DNS服务器确定的该IP地址对应的DNS缓存记录的存留时间。
步骤705，SMF收到DNS服务器发送的DNS查询响应后，当SMF网元根据UE请求的域名确定该域名对应的应用部署在MEC平台上，可选的，进一步地，SMF网元判断该UE是高移动性UE，那么SMF将DNS查询响应中的TTL设置为0或者较小的值。
即DNS查询响应包括第一TTL和域名对应的IP地址，SMF将第一TTL修改成第二TTL，SMF将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。其中，第二TTL小于第一TTL，第二TTL为0或者较小的值。第二TTL为SMF确定的该IP地址 对应的DNS缓存记录的存留时间。
其中，SMF确定第二TTL的方法可以是：SMF基于本地策略将第一TTL修改为0(即第二TTL为0)，或者SMF上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，SMF还根据其他方法确定第二TTL，本发明不做限定。
步骤706，SMF将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。
UE收到TTL之后，如果TTL等于0，代表本次DNS查询的记录不需要缓存，如果TTL比较小，当TTL超时之后，UE自动删除本条DNS缓存记录。
基于该实施例，在会话建立过程中，如果UE签约了某些特定DNAI(MEC平台)部署的应用，SMF从AMF请求获取UE的移动性属性，或者SMF向NWDAF请求该UE的移动性属性，对于高移动性UE，SMF解析DNS消息，如果UE请求了MEC平台上部署的应用对应的域名，SMF对DNS查询响应中的TTL进行修改，例如设置为0或者较小的数值，这样UE每次都会重新向DNS服务器发起域名解析的请求，因而可以保证UE每次进行业务访问的时候，都能访问到当前位置对应的本地应用。
需要说明的是，作为图7的一种扩展方案，当第一网元(UPF或者DNS服务器)收到UE的DNS查询请求时，可以由第一网元将第一存留时间修改为第二存留时间，然后将第二存留时间发送至UE。
如果是UPF修改TTL，则图7实施例的步骤703-步骤706的方案可以替换为以下步骤703’至步骤706’：
步骤703’，SMF将第一指示信息发送至UPF。该第一指示信息用于指示UPF收到来自UE的DNS查询请求后判断该UE请求的域名对应的应用是否部署在MEC平台上，如果该UE请求的域名对应的应用部署在MEC平台上，则UPF需要修改DNS响应中携带的TTL。
可选的，SMF判断该UE是高移动性UE，则SMF将第一指示信息发送至UPF。
步骤704’，UE会根据步骤701获取的DNS服务器的地址发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器，并从DNS服务器接收到DNS查询响应，其中携带应用的域名对应的IP地址和第一TTL。其中，第一TTL为DNS服务器确定的该IP地址对应的DNS缓存记录的存留时间。
步骤705’，UPF根据步骤703’中SMF发送的第一指示信息判断该UE请求的域名对应的应用部署在MEC平台，其中，UPF判断该UE请求的域名对应的应用部署在MEC平台的方法可以是：UPF可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，或者UPF接收SMF发送的第二指示信息，第二指示信息用于指示哪些域名对应的应用部署在MEC平台，本发明不做限定。UPF将第一TTL修改成第二TTL。其中，UPF确定第二TTL的方法可以是：UPF基于本地策略将第一TTL修改为0(即第二TTL为0)，或者UPF上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，UPF还根据其他方法确定第二TTL，本发明不做限定。
步骤706’，UPF将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。
其中，第二TTL小于第一TTL，第二TTL为0或者较小的值。第二TTL为UPF确定的该IP地址对应的DNS缓存记录的存留时间。
UE收到TTL之后，如果TTL等于0，代表本次DNS查询的记录不需要缓存，如果TTL比较小，当TTL超时之后，UE自动删除本条DNS缓存记录。
如果是DNS服务器修改TTL，则图7实施例的步骤703-步骤706可以替换为以下步骤703”至步骤706”：
步骤703”，UE会根据步骤701获取的DNS服务器的地址发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器。
步骤704”，DNS服务器确定应用的域名对应的IP地址。
进一步地，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台。
其中，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台的方法可以是：DNS服务器可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，本发明不做限定。
可选的，DNS服务器还可以进一步判断该UE的移动性属性是否为高移动性。
其中，DNS服务器判断该UE的移动性属性是否为高移动性包括但不限于以下方法：
方法1、接收SMF或UPF发送的指示信息，该指示信息用于指示UE的移动性属性是高移动性。
方法2、接收SMF或UPF发送的UE的移动性属性，该UE的移动性属性是高移动性。
方法3、通过能力开放平台获取UE的移动性属性。
步骤705”，如果DNS服务器确定UE的移动性属性是高移动性，且确定该UE请求的域名对应的应用部署在MEC平台，则将该IP地址对应的DNS缓存记录的存留时间(第一TTL)修改为第二TTL。
需要说明的是，DNS服务器也可以只根据该UE请求的域名对应的应用是否部署在MEC平台来决定是否修改TTL。
其中，DNS服务器确定第二TTL的方法可以是：DNS服务器基于本地策略将第一TTL修改为0(即第二TTL为0)，或者DNS服务器上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，DNS服务器还根据其他方法确定第二TTL，本发明不做限定。
步骤706”DNS服务器将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。其中，第二TTL小于第一TTL，第二TTL为0或者较小的值。
UE收到TTL之后，如果TTL等于0，代表本次DNS查询的记录不需要缓存，如果TTL比较小，当TTL超时之后，UE自动删除本条DNS缓存记录。
如图8所示，为本申请提供的又一种DNS缓存记录的确定方法流程示意图。该实施例是上述图4B所示实施例的一种具体实现。
该实施例方案概述如下：SMF配置不同MEC平台(DNAI)之间的连通能力，例如靠近不同MEC平台的网关之间是否可以直接建立隧道连接，如果不同MEC平台(DNAI)之间的不可以直接连通，那说明UE一旦切换了MEC平台，如果上一次DNS查询的TTL 没有超时，UE无法在当前位置访问旧的MEC平台的应用，因此，该实施例中SMF可以将TTL设置为0或者较小数值，这样UE每次都会重新向DNS服务器发起域名解析的请求，因而可以保证UE每次进行业务访问的时候，都能访问到当前位置对应的本地应用。
举例说明，如图9所示，UE在旧的MEC平台的位置如果发起了DNS查询且获取了旧的MEC平台上应用对应的IP地址和TTL。
场景一：当UE移动到新的MEC平台的位置，如果旧的MEC平台与新的MEC平台之间可以建立数据转发通道，那么当TTL没有超时，UE使用旧的MEC平台上应用对应的IP地址进行业务访问的话，新的MEC平台上的网元仍然可以将数据路由到旧的MEC平台上，即UE通过新的MEC平台，将数据路由到旧的MEC平台，虽然这种数据转发的路径并不优化，但是起码可以保证业务数据的路由。
场景二：当UE移动到新的MEC平台的位置，如果旧的MEC平台与新的MEC平台之间无法建立数据转发通道，可以理解为，这两个不同的MEC平台之间是隔离的，不允许相互之间进行数据转发。那么，当UE移动到新的MEC平台的位置且TTL没有超时，UE使用旧的MEC平台上应用对应的IP地址进行业务访问的话，由于旧的MEC平台与新的MEC平台之间无法建立数据转发通道，即新的MEC平台上的网元无法实现数据路由，因而将会导致业务中断。
所以针对场景二，SMF判断出UE当前访问的MEC平台与其他MEC平台之间无法实现数据转发或者路由，那么SMF可以将DNS查询响应中的TTL进行修改，例如设置为0或者较小的数值，这样可以保证UE在新的MEC平台的位置，发起DNS缓存更新，使用新IP地址进行业务访问。
该方法包括以下步骤：
步骤800，SMF配置不同MEC平台(MEC平台的部署位置用DNAI来标识)之间的连通能力，例如，不同MEC平台的连通能力可以理解为不同MEC平台的网关之间是否可以直接建立隧道连接来实现数据转发。
步骤801，AF将MEC平台上应用的部署位置(应用的部署位置用DNAI来表示)与域名之间的对应关系通过NEF存储到UDR。
步骤802，UE发起了会话建立流程，携带PDU会话标识，S-NSSAI和DNN等参数；AMF根据S-NSSAI和DNN选择SMF，并将该UE的SUPI，UE的位置信息(用TAI来表示UE的位置信息)，PDU会话标识，S-NSSAI和DNN等参数发送给SMF。
步骤803a，SMF向PCF发送策略控制建立请求。相应的，PCF可以接收到该策略控制建立请求。
该策略控制建立请求例如可以是Npcf_SMPolicyControl_Create Request。比如在该会话建立过程中，SMF调用PCF的服务化操作Npcf_SMPolicyControl_Create Request，请求从PCF获取该会话相关的策略信息。
步骤803b，PCF向UDR发送查询请求。相应的，UDR向PCF发送查询响应。
该查询响应包含步骤801中的应用的部署位置(用DNAI来表示)与域名之间的对应关系。
该查询请求例如可以是Nudr_DM_Query。比如PCF调用UDR的服务化操作Nudr_DM_Query，从UDR获取该UE签约的应用相关的信息，其中包含步骤801中的应用的部署位置(用DNAI来表示)与域名之间的对应关系。
步骤801c，PCF根据该应用的部署位置和域名生成PCC规则，并向SMF发送策略控制建立响应，其中携带PCC规则。
该策略控制建立响应例如可以是Npcf_SMPolicyControl_Create Response。比如，PCF通过调用Npcf_SMPolicyControl_Create Response下发至SMF，SMF保存PCC规则，其中包含UE签约的应用的部署位置、域名；另外，PCC规则里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些DNAI可以执行ULCL/BP插入等等。
步骤803d，SMF根据S-NSSAI和DNN等参数选择UPF作为本会话的PSA，并且，SMF向该UPF发送N4会话建立请求，其中携带DNS查询请求的转发规则，用于指示UPF收到UE的DNS查询请求后，将该DNS查询请求转发至SMF。
SMF继续执行该会话建立流程中的其他步骤，由于与本发明无关，这里不赘述。
步骤804，会话建立完成之后，UE根据自己的业务需求，向核心网发送DNS查询请求，发起某个应用的DNS查询，DNS查询请求携带该应用对应的域名，UPF根据步骤803中SMF的指示将UE的DNS查询请求转发到SMF。
步骤805，如果SMF检测到UE请求的域名包含在从步骤803获取的应用的部署位置与域名对应关系里面，则SMF确定UE请求的域名对应的应用的部署位置所在的MEC平台与其他MEC平台之间是否无法实现连通。
这里的连通指的是可以实现数据转发或者路由。
步骤806，SMF将DNS查询请求转发至DNS服务器，并从DNS服务器接收DNS查询响应，DNS查询响应包含域名对应的IP地址和第一TTL。其中，第一TTL为DNS服务器确定的该IP地址对应的DNS缓存记录的存留时间。
步骤807，SMF根据步骤806的判断：如果SMF确定UE请求的域名对应的应用部署位置所在的MEC平台与其他MEC平台之间无法实现连通，则SMF可以将DNS查询响应中的第一TTL修改成第二TTL，例如第二TTL可以为0或者较小的数值，这样可以保证UE移动到新的MEC平台的位置，第二TTL超时后，发起DNS缓存更新，使用新的IP地址进行业务访问。其中，第二TTL为SMF确定的该IP地址对应的DNS缓存记录的存留时间。
其中，SMF确定第二TTL的方法可以是：SMF基于本地策略将第一TTL修改为0(即第二TTL为0)，或者SMF上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，SMF还根据其他方法确定第二TTL，本发明不做限定。
步骤808，SMF将DNS查询响应发送给UE，DNS查询响应包含域名对应的IP地址和第二TTL。
通过该实施例，SMF可以根据UE访问的MEC平台与其他MEC平台之间的连通能力来判断是否修改DNS查询响应中的TTL，从而触发UE进行DNS缓存更新。
需要说明的是，图8所示的方案中，当第一网元(UPF或者DNS服务器)收到UE的DNS查询请求时，可以由第一网元将第一存留时间修改为第二存留时间，然后将第二存留时间发送至UE。
如果是UPF修改TTL，图8实施例中的步骤803-步骤808的替换为以下步骤803’至步骤806’：
步骤803’，在该会话建立过程中，SMF调用PCF的服务化操作Npcf_SMPolicyControl_Create Request，请求从PCF获取该会话相关的策略信息，PCF调用UDR的服务化操作Nudr_DM_Query，从UDR获取该UE签约的应用相关的信息，其中包含步骤801中的应用的部署位置(用DNAI来表示)与域名之间的对应关系。PCF根据该应用的部署位置和域名生成PCC规则，通过Npcf_SMPolicyControl_Create Response下发至SMF，SMF保存PCC规则，其中包含UE签约的应用的部署位置、域名；另外，PCC规则里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些DNAI可以执行ULCL/BP插入等等。
SMF根据S-NSSAI和DNN等参数选择UPF作为本会话的PSA，并且，SMF向该UPF发送N4会话建立请求，其中携带第一指示信息。该第一指示信息用于指示UPF收到来自UE的DNS查询请求后判断该UE请求的域名对应的应用是否部署在MEC平台上，如果该UE请求的域名对应的应用部署在MEC平台上，且该MEC平台与其他MEC平台之间无法实现连通，则UPF需要修改DNS响应中携带的TTL。
步骤804’，UE发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器，并从DNS服务器接收到DNS查询响应，其中携带应用的域名对应的IP地址和第一TTL。其中，第一TTL为DNS服务器确定的该IP地址对应的DNS缓存记录的存留时间。
步骤805’，UPF根据步骤803’中SMF发送的第一指示信息判断该UE请求的域名对应的应用部署在MEC平台，其中，UPF判断该UE请求的域名对应的应用部署在MEC平台的方法可以是：UPF可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，或者UPF接收SMF发送的第二指示信息，第二指示信息用于指示哪些域名对应的应用部署在MEC平台，本发明不做限定。
进一步地，UPF判断UE请求的域名对应的应用所在的MEC平台与其他MEC平台之间无法实现连通，这里的连通指的是可以实现数据转发或者路由。则UPF将第一TTL修改成第二TTL。第二TTL为UPF确定的该IP地址对应的DNS缓存记录的存留时间。
其中，UPF确定第二TTL的方法可以是：UPF基于本地策略将第一TTL修改为0(即第二TTL为0)，或者UPF上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，UPF还根据其他方法确定第二TTL，本发明不做限定。
步骤806’，UPF第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。其中，第二TTL小于第一TTL，第二TTL为0或者较小的值。第二TTL为UPF确定的该IP地址对应的DNS缓存记录的存留时间。
如果是DNS服务器修改TTL，则图8实施例的步骤803-步骤805的方案可以替换为以下步骤803”至步骤806”：
步骤803”，在该会话建立过程中，SMF调用PCF的服务化操作Npcf_SMPolicyControl_Create Request，请求从PCF获取该会话相关的策略信息，PCF调用UDR的服务化操作Nudr_DM_Query，从UDR获取该UE签约的应用相关的信息，其中包含步骤801中的应用的部署位置(用DNAI来表示)与域名之间的对应关系。PCF根据该 应用的部署位置和域名生成PCC规则，通过Npcf_SMPolicyControl_Create Response下发至SMF，SMF保存PCC规则，其中包含UE签约的应用的部署位置、域名；另外，PCC规则里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些DNAI可以执行ULCL/BP插入等等。
SMF根据S-NSSAI和DNN等参数选择UPF作为本会话的PSA，并且，SMF向该UPF发送N4会话建立请求。
步骤804”，UE发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器。
步骤805”，DNS服务器确定应用的域名对应的IP地址。
进一步地，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台。
其中，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台的方法可以是：DNS服务器可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，本发明不做限定。
之后，DNS服务器判断UE请求的域名对应的应用所在的MEC平台与其他MEC平台之间无法实现连通，这里的连通指的是可以实现数据转发或者路由。则DNS服务器将该IP地址对应的DNS缓存记录的存留时间(第一TTL)修改为第二TTL。
其中，DNS服务器确定第二TTL的方法可以是：DNS服务器基于本地策略将第一TTL修改为0(即第二TTL为0)，或者DNS服务器上配置第一阈值，第二TTL为不大于预设的第一阈值的正数。示例性地，第一阈值可以为100秒或者1分钟。需要说明的是，DNS服务器还根据其他方法确定第二TTL，本发明不做限定。
步骤806”，DNS服务器将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。其中，第二TTL小于第一TTL，第二TTL为0或者较小的值。
UE收到TTL之后，如果TTL等于0，代表本次DNS查询的记录不需要缓存，如果TTL比较小，当TTL超时之后，UE自动删除本条DNS缓存记录。
如图10所示，为本申请提供的又一种DNS缓存记录的确定方法流程示意图。该实施例是上述图4B所示实施例的一种具体实现。
该实施例与图7和图8实施例的不同之处在于：前面两个实施例都是如何保证UE尽可能地在新的MEC平台上发起DNS缓存更新来使用新的IP地址进行业务访问，而图10实施例提供了另一种场景，即IP地址是任播地址的场景。
该实施例方案概述如下：SMF获知UE请求的域名对应的应用在不同MEC平台上具备任播地址，SMF将DNS查询响应中的TTL修改为较大的数值，这样即便在TTL超时之前，UE使用了任播地址访问业务，UPF仍然可以根据任播地址实现就近访问本地应用。
该方法包括以下步骤：
步骤1001，MEC平台将应用的部署位置(用DNAI来表示)、域名和IP地址之间的对应关系通过NEF存储到UDR里面。
其中，该IP地址是任播地址。
步骤1002，UE发起了会话建立流程，携带PDU会话标识，S-NSSAI和DNN等参数；AMF根据S-NSSAI和DNN选择SMF，并将该UE的SUPI，UE的位置信息(用TAI来 表示UE的位置信息)，PDU会话标识，S-NSSAI和DNN等参数发送给SMF。
步骤1003a，SMF向PCF发送策略控制建立请求。相应的，PCF可以接收到该策略控制建立请求。
该策略控制建立请求例如可以是Npcf_SMPolicyControl_Create Request。比如在该会话建立过程中，SMF调用PCF的服务化操作Npcf_SMPolicyControl_Create Request，请求从PCF获取该会话相关的策略信息。
步骤1003b，PCF向UDR发送查询请求。相应的，UDR向PCF发送查询响应。
该查询响应包含步骤1001中的应用的部署位置(用DNAI来表示)、域名和IP地址之间的对应关系。比如，PCF调用UDR的服务化操作Nudr_DM_Query，从UDR获取该UE签约的应用相关的信息，其中包含步骤1001中的应用的部署位置(用DNAI来表示)、域名和IP地址之间的对应关系。
步骤1003c，PCF根据该应用的部署位置、域名和IP地址生成PCC规则，并向SMF发送策略控制建立响应，其中携带PCC规则。
该策略控制建立响应例如可以是Npcf_SMPolicyControl_Create Response。比如，PCF通过调用Npcf_SMPolicyControl_Create Response下发至SMF，SMF保存PCC规则，其中包含UE签约的应用的部署位置、域名和IP地址；另外，PCC规则里面还可能包含其他规则，例如，计费规则，报文转发规则，以及哪些DNAI可以执行ULCL/BP插入等等。
步骤1003d，SMF根据S-NSSAI和DNN等参数选择UPF网元作为本会话的PSA，并且，SMF向该UPF发送N4会话建立请求，其中携带DNS查询请求的转发规则，用于指示UPF收到UE的DNS查询请求后，将该DNS查询请求转发至SMF。
SMF继续执行该会话建立流程中的其他步骤，由于与本发明无关，这里不赘述。
步骤1004，会话建立完成之后，UE根据自己的业务需求，向核心网发送DNS查询请求，发起某个应用的DNS查询，DNS查询请求携带该应用对应的域名，UPF根据步骤1003中SMF的指示将UE的DNS查询请求转发到SMF。
步骤1005，如果SMF检测UE请求的域名如果包含在步骤1003获取的应用的部署位置、域名和IP地址对应关系里面，则根据UE当前位置(TAI)确定DNAI，并确定DNAI对应的IP地址；同时SMF判断出该IP地址是一个任播地址，且UE请求的域名对应的应用部署在多个MEC平台上，采用的都是任播地址。
步骤1006，SMF将该IP地址对应的TTL设置成一个比较大的数值。
步骤1007，SMF返回DNS查询响应，DNS查询响应中包含UE请求的域名对应的IP地址以及TTL。
通过该实施例，SMF获知UE请求的域名对应的应用在不同MEC平台上具备任播地址，SMF将DNS查询响应中的TTL修改为较大的数值，这样即便在TTL超时之前，UE使用了任播地址访问业务，但是UPF可以根据任播地址实现就近访问本地应用。
需要说明的是，作为图10的一种扩展方案，当第一网元(UPF或者DNS服务器)收到UE的DNS查询请求时，可以由第一网元将第一存留时间修改为第二存留时间，然后将第二存留时间发送至UE。
如果是UPF修改TTL，则图10实施例的步骤1003-步骤1007的方案可以替换为以下步骤1003’至步骤1006’：
步骤1003’，SMF将第一指示信息发送至UPF。该第一指示信息用于指示UPF收到来自UE的DNS查询请求后判断该UE请求的域名对应的应用是否部署在MEC平台上，如果该UE请求的域名对应的应用部署在MEC平台上，则UPF需要修改DNS响应中携带的TTL。
可选的，该第一指示信息还包括用于指示UPF收到来DNS服务器的DNS查询请求响应后判断UE请求的域名对应的IP地址是否为任播地址，如果UE请求的域名对应的IP地址是任播地址且UE请求的域名对应的应用部署在MEC平台上，则UPF需要修改DNS响应中携带的TTL。
步骤1004’，UE会根据步骤1001获取的DNS服务器的地址发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器，并从DNS服务器接收到DNS查询响应，其中携带应用的域名对应的IP地址和第一TTL。其中，第一TTL为DNS服务器确定的该IP地址对应的DNS缓存记录的存留时间。
步骤1005’，UPF根据步骤1003’中SMF发送的第一指示信息判断该UE请求的域名对应的应用部署在MEC平台，其中，UPF判断该UE请求的域名对应的应用部署在MEC平台的方法可以是：UPF可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，或者UPF接收SMF发送的第二指示信息，第二指示信息用于指示哪些域名对应的应用部署在MEC平台，本发明不做限定。UPF将第一TTL修改成第二TTL。
可选的，UPF根据步骤1003’中SMF发送的第一指示信息判断该UE请求的域名对应的应用部署在MEC平台，且DNS查询响应中包含的IP地址是任播地址，UPF将第一TTL修改成第二TTL。
其中，UPF确定第二TTL的方法可以是：UPF上配置第二阈值，第二TTL为不小于第二阈值的任一数值。示例性地，第二阈值可以是10小时。需要说明的是，UPF还根据其他方法确定第二TTL，本发明不做限定。
步骤1006’，UPF将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。
如果是DNS服务器修改TTL，则图10实施例的步骤1003-步骤1007的方案可以替换为以下步骤1003”至步骤1005”：
步骤1003”，UE会根据步骤1001获取的DNS服务器的地址发起DNS查询请求，DNS查询请求中携带UE请求的域名，源地址(UE的IP地址)，目的地址(DNS服务器的地址)，UPF收到UE的DNS查询请求后，发给DNS服务器。
步骤1004”，DNS服务器确定应用的域名对应的IP地址。
进一步地，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台，如果UE请求的域名对应的应用部署在MEC平台，则将第一TTL修改成第二TTL。
其中，DNS服务器判断该UE请求的域名对应的应用是否部署在MEC平台的方法可以是：DNS服务器可以存储配置信息，该配置信息包含了哪些域名对应的应用部署在MEC平台，本发明不做限定。
可选的，DNS服务器还可以判断该UE请求的域名对应的IP地址是否为任播地址,如果UE请求的域名对应的应用部署在MEC平台，且应用的域名对应的IP地址是任播地址，则DNS服务器将第一TTL修改成第二TTL。
其中，DNS服务器确定第二TTL的方法可以是：DNS服务器上配置第二阈值，第二TTL为不小于第二阈值的任一数值。示例性地，第二阈值可以是10小时。需要说明的是，DNS服务器还根据其他方法确定第二TTL，本发明不做限定。
步骤1005”，DNS服务器将第二TTL以及域名对应的IP地址通过DNS查询响应发送至UE。
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。
本申请实施例还提供用于实现以上任一种方法的装置，例如，提供一种装置包括用以实现以上任一种方法中终端设备所执行的各个步骤的单元(或手段)。再如，还提供另一种装置，包括用以实现以上任一种方法中会话管理网元所执行的各个步骤的单元(或手段)。
例如，请参考图11，其为本申请实施例提供的一种DNS缓存记录的确定装置的示意图。该装置用于终端设备，如图11所示，该装置1100包括位置确定单元1110和更新单元1120。可选的，还可以包括接收单元1130和发送单元1140。位置确定单元1110，用于确定数据网络接入标识DNAI发生改变。更新单元1120，用于更新DNS缓存记录，更新后的DNS缓存记录至少包括应用的域名或所述域名对应的应用服务器的互联网协议IP地址的一种，所述应用服务器与改变后的DNAI对应。
在一种可能的实现方法中，接收单元1130，用于接收DNAI改变指示；位置确定单元1110，具体用于根据所述DNAI改变指示确定DNAI发生改变。
在又一种可能的实现方法中，位置确定单元1110，具体用于确定移动后所在的位置对应的DNAI，与移动前所在的位置对应的DNAI不同，则确定DNAI发生改变。
在一种可能的实现方法中，发送单元1140，用于发送更新缓存请求，所述更新缓存请求包括所述应用的域名；接收单元1130，用于接收更新缓存响应，所述更新缓存响应包括所述IP地址和存留时间，所述存留时间为所述IP地址对应的DNS缓存记录的存留时间；更新单元1120，具体用于根据所述IP地址，更新DNS缓存记录。
例如，请参考图12，其为本申请实施例提供的又一种DNS缓存记录的确定装置的示意图。该装置用于会话管理网元，如图12所示，该装置1200包括位置接收单元1210、处理单元1220和发送单元1230。接收单元1210，用于接收来自终端设备的第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址；发送单元1230，用于向所述DNS服务器发送第二DNS查询请求，所述第二DNS查询请求包含所述域名；接收单元1210，还用于从所述DNS服务器接收所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间；处理单元1220，用于确定满足第一条件，将所述第一存留时间修改为第二存留时间；发送单元1230，还用于向所述终端设备发送所述IP地址和所述第二存留时间，所述IP地址和所述第二存 留时间用于所述终端设备确定所述IP地址对应的DNS缓存记录。
在一种可能的实现方法中，所述第一条件包括：所述终端设备的移动性属性为高移动性。
在一种可能的实现方法中，接收单元1210，还用于从移动性管理网元或数据管理网元获取所述终端设备的移动性属性。
在一种可能的实现方法中，所述第一条件包括：所述域名对应的第一应用服务器所在的第一移动边缘计算MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通。
在一种可能的实现方法中，所述第二存留时间小于所述第一存留时间，所述第二存留时间等于0、或为不大于预设的第一阈值的正数。
在一种可能的实现方法中，所述第一条件包括：所述IP地址是一个任播地址。
在一种可能的实现方法中，所述第二存留时间大于所述第一存留时间，所述第二存留时间不小于预设的第二阈值。
在一种可能的实现方法中，所述第一条件包括：所述域名对应的第一应用服务器部署在MEC平台上。
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。
以上用于接收的单元(例如接收单元)是一种该装置的接口电路，用于从其它装置接收信号。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。以上用于发送的单元(例如发送单元)是一种该装置的接口电路，用于向其它装置发送信号。例如，当该装置以芯片的方式实现时，该发送单元是该芯片用于向其它芯片或装置发送信号的接口电路。
请参考图13，其为本申请实施例提供的一种终端设备的结构示意图。该终端设备用于实现以上实施例中终端设备的操作。如图13所示，该终端设备包括：天线1310、射频装置1320、信号处理部分1330。天线1310与射频装置1320连接。在下行方向上，射频装 置1320通过天线1310接收接入网设备发送的信息，将接入网设备发送的信息发送给信号处理部分1330进行处理。在上行方向上，信号处理部分1330对终端设备的信息进行处理，并发送给射频装置1320，射频装置1320对终端设备的信息进行处理后经过天线1310发送给接入网设备。
信号处理部分1330用于实现对数据各通信协议层的处理。信号处理部分1330可以为该终端设备的一个子系统，则该终端设备还可以包括其它子系统，例如中央处理子系统，用于实现对终端设备操作系统以及应用层的处理；再如，周边子系统用于实现与其它设备的连接。信号处理部分1330可以为单独设置的芯片。可选的，以上的装置可以位于信号处理部分1330。
信号处理部分1330可以包括一个或多个处理元件1331，例如，包括一个主控CPU和其它集成电路。此外，该信号处理部分1330还可以包括存储元件1332和接口电路1333。存储元件1332用于存储数据和程序，用于执行以上方法中终端设备所执行的方法的程序可能存储，也可能不存储于该存储元件1332中，例如，存储于信号处理部分1330之外的存储器中，使用时信号处理部分1330加载该程序到缓存中进行使用。接口电路1333用于与装置通信。以上装置可以位于信号处理部分1330，该信号处理部分1330可以通过芯片实现，该芯片包括至少一个处理元件和接口电路，其中处理元件用于执行以上终端设备执行的任一种方法的各个步骤，接口电路用于与其它装置通信。在一种实现中，实现以上方法中各个步骤的单元可以通过处理元件调度程序的形式实现，例如该装置包括处理元件和存储元件，处理元件调用存储元件存储的程序，以执行以上方法实施例中终端设备执行的方法。存储元件可以为处理元件处于同一芯片上的存储元件，即片内存储元件。
在另一种实现中，用于执行以上方法中终端设备所执行的方法的程序可以在与处理元件处于不同芯片上的存储元件，即片外存储元件。此时，处理元件从片外存储元件调用或加载程序于片内存储元件上，以调用并执行以上方法实施例中终端设备执行的方法。
在又一种实现中，终端设备实现以上方法中各个步骤的单元可以是被配置成一个或多个处理元件，这些处理元件设置于信号处理部分1330上，这里的处理元件可以为集成电路，例如：一个或多个ASIC，或，一个或多个DSP，或，一个或者多个FPGA，或者这些类集成电路的组合。这些集成电路可以集成在一起，构成芯片。
实现以上方法中各个步骤的单元可以集成在一起，以片上系统(system-on-a-chip，SOC)的形式实现，该SOC芯片，用于实现以上方法。该芯片内可以集成至少一个处理元件和存储元件，由处理元件调用存储元件的存储的程序的形式实现以上终端设备执行的方法；或者，该芯片内可以集成至少一个集成电路，用于实现以上终端设备执行的方法；或者，可以结合以上实现方式，部分单元的功能通过处理元件调用程序的形式实现，部分单元的功能通过集成电路的形式实现。
可见，以上装置可以包括至少一个处理元件和接口电路，其中至少一个处理元件用于执行以上方法实施例所提供的任一种终端设备执行的方法。处理元件可以以第一种方式：即调用存储元件存储的程序的方式执行终端设备执行的部分或全部步骤；也可以以第二种方式：即通过处理器元件中的硬件的集成逻辑电路结合指令的方式执行终端设备执行的部分或全部步骤；当然，也可以结合第一种方式和第二种方式执行终端设备执行的部分或全部步骤。
这里的处理元件同以上描述，可以是通用处理器，例如CPU，还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。存储元件可以是一个存储器，也可以是多个存储元件的统称。
请参考图14，其为本申请实施例提供的一种会话管理网元的结构示意图，用于实现以上实施例中会话管理网元的操作。如图14所示，该会话管理网元包括：处理器1410，存储器1420，和接口1430，处理器1410、存储器1420和接口1430信号连接。
以上实施例中会话管理网元执行的方法可以通过处理器1410调用存储器1420中存储的程序来实现。即，用于会话管理网元的装置包括存储器和处理器，存储器用于存储程序，该程序被处理器调用，以执行以上方法实施例中的会话管理网元执行的方法。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。用于会话管理网元的装置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。
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。
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。
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。
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 (32)

  1. 一种域名系统DNS缓存记录的确定方法，其特征在于，包括：
    终端设备确定数据网络接入标识DNAI发生改变；
    所述终端设备更新DNS缓存记录，更新后的DNS缓存记录至少包括应用的域名或所述域名对应的应用服务器的互联网协议IP地址的一种，所述IP地址与改变后的DNAI对应。
  2. 如权利要求1所述的方法，其特征在于，所述终端设备确定DNAI发生改变，包括：
    所述终端设备接收DNAI改变指示，根据所述DNAI改变指示确定DNAI发生改变；或者，
    所述终端设备确定移动后所在的位置对应的DNAI，与移动前所在的位置对应的DNAI不同，则确定DNAI发生改变。
  3. 如权利要求1或2所述的方法，其特征在于，所述终端设备更新DNS缓存记录，包括：
    所述终端设备发送更新缓存请求，所述更新缓存请求包括所述应用的域名；
    所述终端设备接收更新缓存响应，所述更新缓存响应包括所述IP地址；
    所述终端设备根据所述IP地址，更新DNS缓存记录。
  4. 一种DNS缓存记录的确定方法，其特征在于，包括：
    核心网网元接收来自终端设备的第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址；
    所述核心网网元向所述DNS服务器发送第二DNS查询请求，所述第二DNS查询请求包含所述域名；
    所述核心网网元从所述DNS服务器接收所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间；
    所述核心网网元确定满足第一条件，将所述第一存留时间修改为第二存留时间；
    所述核心网网元向所述终端设备发送所述IP地址和所述第二存留时间，所述IP地址和所述第二存留时间用于所述终端设备确定所述IP地址对应的DNS缓存记录。
  5. 如权利要求4所述的方法，其特征在于，所述第一条件包括：所述终端设备的移动性属性为高移动性。
  6. 如权利要求5所述的方法，其特征在于，还包括：
    所述核心网网元从移动性管理网元或数据管理网元获取所述终端设备的移动性属性。
  7. 如权利要求4所述的方法，其特征在于，所述第一条件包括：所述域名对应的第一应用服务器所在的第一移动边缘计算MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通。
  8. 如权利要求5-7任一所述的方法，其特征在于，所述第二存留时间小于所述第一存留时间，所述第二存留时间等于0、或为不大于预设的第一阈值的正数。
  9. 如权利要求4所述的方法，其特征在于，所述第一条件包括：所述IP地址是一个任播地址。
  10. 如权利要求9所述的方法，其特征在于，所述第二存留时间大于所述第一存留时 间，所述第二存留时间不小于预设的第二阈值。
  11. 如权利要求4-10任一所述的方法，其特征在于，所述第一条件包括：所述域名对应的第一应用服务器部署在MEC平台上。
  12. 一种域名系统DNS缓存记录的确定装置，其特征在于，包括：
    位置确定单元，用于确定数据网络接入标识DNAI发生改变；
    更新单元，用于更新DNS缓存记录，更新后的DNS缓存记录包括应用的域名和所述域名对应的应用服务器的互联网协议IP地址，所述IP地址与改变后的DNAI对应。
  13. 如权利要求12所述的装置，其特征在于，所述装置还包括接收单元，用于接收DNAI改变指示；所述位置确定单元，具体用于根据所述DNAI改变指示确定DNAI发生改变；或者，
    所述位置确定单元，具体用于确定移动后所在的位置对应的DNAI，与移动前所在的位置对应的DNAI不同，则确定DNAI发生改变。
  14. 如权利要求12或13所述的装置，其特征在于，所述装置还包括发送单元，用于发送更新缓存请求，所述更新缓存请求包括所述应用的域名；
    所述装置还包括接收单元，用于接收更新缓存响应，所述更新缓存响应包括所述IP地址；
    所述更新单元，具体用于根据所述IP地址，更新DNS缓存记录。
  15. 一种DNS缓存记录的确定装置，其特征在于，包括接收单元、发送单元和处理单元；
    所述接收单元，用于接收来自终端设备的第一DNS查询请求，所述第一DNS查询请求包含域名和DNS服务器的地址；
    所述发送单元，用于向所述DNS服务器发送第二DNS查询请求，所述第二DNS查询请求包含所述域名；
    所述接收单元，还用于从所述DNS服务器接收所述域名对应的第一应用服务器的IP地址和第一存留时间，所述第一存留时间为所述IP地址对应的DNS缓存记录的存留时间；
    所述处理单元，用于确定满足第一条件，将所述第一存留时间修改为第二存留时间；
    所述发送单元，还用于向所述终端设备发送所述IP地址和所述第二存留时间，所述IP地址和所述第二存留时间用于所述终端设备确定所述IP地址对应的DNS缓存记录。
  16. 如权利要求15所述的装置，其特征在于，所述第一条件包括：所述终端设备的移动性属性为高移动性。
  17. 如权利要求16所述的装置，其特征在于，所述接收单元，还用于从移动性管理网元或数据管理网元获取所述终端设备的移动性属性。
  18. 如权利要求15所述的装置，其特征在于，所述第一条件包括：所述域名对应的第一应用服务器所在的第一移动边缘计算MEC平台与所述域名对应的第二应用服务器所在的第二MEC平台之间无法实现互通。
  19. 如权利要求16-18任一所述的装置，其特征在于，所述第二存留时间小于所述第一存留时间，所述第二存留时间等于0、或为不大于预设的第一阈值的正数。
  20. 如权利要求15所述的装置，其特征在于，所述第一条件包括：所述IP地址是一个任播地址。
  21. 如权利要求20所述的装置，其特征在于，所述第二存留时间大于所述第一存留 时间，所述第二存留时间不小于预设的第二阈值。
  22. 如权利要求15-21任一所述的装置，其特征在于，所述第一条件包括：所述域名对应的第一应用服务器部署在MEC平台上。
  23. 一种通信装置，其特征在于，包括：用于执行权利要求1-3任一所述的各个步骤的单元。
  24. 一种通信装置，其特征在于，包括：处理器，用于调用存储器中的程序，以执行权利要求1-3任一所述的方法。
  25. 一种通信装置，其特征在于，包括：处理器和接口电路，所述接口电路用于与其它装置通信，所述处理器用于执行权利要求1-3任一所述的方法。
  26. 一种通信装置，其特征在于，包括：用于执行权利要求4-11任一所述的各个步骤的单元。
  27. 一种通信装置，其特征在于，包括：处理器，用于调用存储器中的程序，以执行权利要求4-11任一所述的方法。
  28. 一种通信装置，其特征在于，包括：处理器和接口电路，所述接口电路用于与其它装置通信，所述处理器用于执行权利要求4-11任一所述的方法。
  29. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储程序，所述程序被处理器调用时，权利要求1-3任一所述的方法被执行。
  30. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储程序，所述程序被处理器调用时，权利要求4-11任一所述的方法被执行。
  31. 一种计算机程序，其特征在于，当所述程序被处理器调用时，权利要求1-3任一所述的方法被执行。
  32. 一种计算机程序，其特征在于，当所述程序被处理器调用时，权利要求4-11任一所述的方法被执行。
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