Communication methods, devices, and systems

Abstract

Embodiments of the present invention relate to the field of communication technology and provide a communication method, apparatus, and system for selecting a better edge application server for a terminal when the terminal leaves a terminal set. The method includes a first network element determining that a first terminal has been disassociated from a first terminal set. Based on the fact that the first terminal has been disassociated from the first terminal set, the first network element decides to transmit a second data network access identifier for the first terminal to a second network element, or to transmit first instruction information to the first terminal, the first instruction information relating to the re-selection of an edge application server by the first terminal. In this solution, the first terminal may trigger an edge application server migration in order to select a better edge application server for the first terminal after the first network element has determined that the first terminal has left the first terminal set. In this way, latency for the first terminal is reduced and the user experience is improved.

Description

Technical Field

[0001] This application claims priority based on Chinese Patent Application No. 202310541117.X, entitled "COMMUNICATION METHOD, APPARATUS, AND SYSTEM", filed with the China National Intellectual Property Administration on May 12, 2023, the entire content of which is incorporated herein by reference.

[0002] [Technical Field] This application relates to the field of edge computing, and in particular, to communication methods, apparatuses, and systems.

Background Art

[0003] Edge computing (EC) was proposed when the anchor gateway deployed in a centralized manner could not meet the requirements of the explosive growth of current mobile service traffic. Distributed service traffic is mainly processed locally by moving user plane function (UPF) network elements and service processing capabilities to the network edge. In the EC deployment scenario, multiple edge application servers (EASs) can provide services to terminals. Multiple EASs provide the same services and content, but the EASs have different Internet protocol (IP) addresses. Therefore, when a terminal needs to access a service, the terminal needs to obtain the IP address of the EAS.

[0004] Currently, in new e-commerce scenarios, the concept of terminal sets is introduced for certain services. In other words, a set of terminals may access the same EAS, which may be called a common edge application server (common EAS), or terminal sets may access the same DNAI, which may be called a common data network access identifier (common DNAI). Terminal sets are dynamic; in other words, terminals can join or leave a terminal set at any time. [Overview of the Initiative] [Means for solving the problem]

[0005] This invention provides a communication method, apparatus, and system for re-selecting an edge application server for a terminal when the terminal leaves a terminal set.

[0006] To achieve the above-mentioned objectives, embodiments of the present invention provide the following technical solutions.

[0007] In a first aspect, one embodiment of the present application provides a communication method comprising the steps of: a first network element determining that a first terminal has been disassociated from a first terminal set, the first terminal set comprising one or more terminals, the one or more terminals accessing a first edge application server or a first data network access identifier; the first network element transmitting a second data network access identifier of the first terminal to a second network element, or transmitting first instruction information to the first terminal.

[0008] For example, the first instruction information relates to triggering the rediscovery of the edge application server. For example, the first network element could be a session management network element, and the second network element could be an application network element.

[0009] According to the communication method provided in this embodiment of the present application, when the method determines that a first terminal has been disassociated from a first terminal set, the first network element transmits a second data network access identifier of the first terminal to a second network element, or transmits first instruction information to the first terminal, thereby triggering the second network element to select an edge application server suitable for providing services for the first terminal, or the first terminal to perform edge application server rediscovery to select an edge application server suitable for providing services. In this solution, after the first terminal leaves the first terminal set, an edge application server migration may be triggered to re-select an edge application server for the first terminal. In this way, latency for the first terminal can be reduced and the user experience can be improved.

[0010] In possible implementations, the first instruction information is used to clear cached edge application server information. Clearing can be described as refreshing.

[0011] In possible implementations, the first instruction information further instructs the first terminal to clear the Domain Name System cache, or the first network element sends instruction information to the first terminal instructing it to clear the Domain Name System cache. In this way, the first terminal clears the Domain Name System cache and frees Domain Name System memory based on the instruction.

[0012] In possible implementations, the method provided in this embodiment of the Application further includes a first network element transmitting Domain Name System Clear Instruction information, which instructs a first terminal to clear the Domain Name System cache. In this way, the first terminal clears the Domain Name System cache and frees Domain Name System memory based on the instruction.

[0013] In possible implementations, the first instruction information includes a service identifier, and when the first instruction information includes a service identifier, the first terminal clears the DNS cache associated with the service identifier.

[0014] In possible implementations, the service identifier could be a service data flow, an application identifier, a fully qualified domain name, or something similar.

[0015] In possible implementations, the method provided in this embodiment of the Application may further include the first network element determining the second data network access identifier when the first network element determines that the first terminal has been disassociated from the first terminal set, before the first network element transmits the second data network access identifier of the first terminal to the second network element or transmits first instruction information to the first terminal. For example, the second data network access identifier is used to determine the edge application server of the first terminal.

[0016] In possible implementations, the method provided in this embodiment of the Application may further include the first terminal being disassociated from a first terminal set, a first edge application server or an edge application server corresponding to a first data network access identifier being unsuitable to service the first terminal, and a first network element determining a second data network access identifier. In this solution, when the first terminal is disassociated from a first terminal set and a first edge application server or an edge application server corresponding to a first data network access identifier is unsuitable to service the first terminal, a suitable edge application server can be reselected for the first terminal.

[0017] In a possible implementation, if the first network element determines that the first edge application server is suitable to serve the first terminal, the first network element determines that the second data network access identifier does not need to be sent to the second network element. If the first network element determines that the first edge application server is not suitable to serve the first terminal, the first network element sends the second data network access identifier to the second network element.

[0018] In a possible implementation, the method provided in this embodiment of the Application further includes the step of the first network element receiving second instruction information before the first network element determines that the first terminal has been disassociated from the first terminal set. The first network element determines that the first terminal has been disassociated from the first terminal set by using the second instruction information. For example, the first network element may receive second instruction information from the second network element.

[0019] In a possible implementation, before the first network element determines that the first terminal has been disassociated from the first terminal set, the method provided in this embodiment of the Application may further include the steps of: the first network element receives a first message, the first message comprising an identifier for the first terminal set and third directive information, the third directive information indicating that each terminal in the first terminal set needs to access a first edge application server or a first data network access identifier; the first network element receives a second message, the second message not comprising an identifier for the first terminal set and / or third directive information, or the second message comprising second directive information, the second directive information indicating that the first terminal has been disassociated from the first terminal set. In response, the first network element's determination that the first terminal has been disassociated from the first terminal set includes the first network element determining, based on the first message and the second message, that the first terminal has been disassociated from the first terminal set. In this solution, the first network element may determine that the first terminal has been disassociated from the first terminal set by comparing the first message with the second message.

[0020] In possible implementations, the first message further includes a third identifier, which is used to determine the service associated with the first set of terminals.

[0021] In a possible implementation, the first message includes a PCC rule, which includes a traffic correlation identifier and a directive for a first edge application server or a first data network access identifier.

[0022] In possible implementations, the second message contains the updated PCC rule. The updated PCC rule does not contain the traffic correlation identifier and / or the directive information for the first edge application server, or the directive information for the first data network access identifier.

[0023] In a possible implementation, the method provided in this embodiment of the Application may further include the step of the first network element receiving identification information for one or more terminals in the first terminal set and identification information for the first terminal, before the first network element determines that the first terminal has been disassociated from the first terminal set. The first network element receives updated identification information for terminals in the first terminal set. The updated identification information for terminals in the first terminal set does not include identification information for the first terminal. In this case, the first network element may determine that the first terminal has been disassociated from the first terminal set based on the identification information for terminals in the first terminal set and the updated identification information for terminals in the first terminal set.

[0024] In a possible implementation, the method provided in this embodiment of the Application may further include the first network element deciding to transmit the second data network access identifier of the first terminal to the second network element before the first network element transmits the second data network access identifier of the first terminal to the second network element.

[0025] In possible implementations, the method provided in this embodiment of the present application may further include the first network element transmitting fourth instruction information to a second network element, which instructs the first terminal to select a second edge application server.

[0026] In possible implementations, the method provided in this embodiment of the Application may further include a first network element receiving edge application server address substitution information, which is then used by the first terminal to connect to a second edge application server.

[0027] In a possible implementation, before the first network element transmits the first instruction information to the first terminal, the method provided in the present embodiment of the present application may further include the first network element determining to transmit the first instruction information to the first terminal. The first instruction information may instruct the first terminal to perform edge application server rediscovery.

[0028] In a possible implementation, the second message received by the first network element includes identifiers of a second set of terminals, and a plurality of terminals within the second set of terminals need to access a third edge application server or a third data network access identifier.

[0029] According to a second aspect, an embodiment of the present application provides a communication method, and the second network element includes determining that the first terminal has been disassocated from the first set of terminals. The first set of terminals includes one or more terminals that access a first edge application server or a first data network access identifier. The second network element determines a second edge application server corresponding to the first terminal, or transmits edge application server rediscovery-related instruction information to the first network element, or transmits edge application server relocation-related information to the first network element.

[0030] In the foregoing solution, when it is determined that the first terminal has been disassocated from the first set of terminals, the second network element may determine a second edge application server corresponding to the first terminal, or trigger the first network element to perform rediscovery of the edge application server, thereby reducing the implementation logic of the first network element.

[0031] In a possible implementation, the method provided in this embodiment of the Application may further include the second network element determining a second data network access identifier for the first terminal before the second network element decides to determine a second edge application server corresponding to the first terminal or to transmit edge application server relocation information to the first network element. Correspondingly, the second network element determining a second edge application server corresponding to the first terminal includes the second network element determining a second edge application server based on the second data network access identifier.

[0032] In possible implementations, the determination of the second data network access identifier of the first terminal by the second network element includes the second network element receiving the second data network access identifier of the first terminal from the first network element. For example, the first network element may proactively transmit the second data network access identifier of the first terminal to the second network element. Alternatively, the second network element may send a subscription message to the first network element in advance, which is then used by the first network element to provide the second data network access identifier of the first terminal.

[0033] In a possible implementation, the determination of the second data network access identifier of the first terminal by the second network element includes the second network element requesting the second data network access identifier of the first terminal from the first network element. The second network element receives the second data network access identifier from the first network element.

[0034] In a possible implementation, a second network element requesting a second data network access identifier for a first terminal from a first network element includes the second network element transmitting a fifth instruction information to the first network element. The fifth instruction information is used to request the second data network access identifier for the first terminal.

[0035] In a possible implementation, after the second network element determines the second edge application server corresponding to the first terminal, the method provided in this embodiment of the Application may further include the second network element transmitting address information of the second edge application server to the first network element. The address information of the second edge application server is used by the first terminal to connect to the second edge application server.

[0036] According to a third aspect, one embodiment of the present application provides a communication method comprising a second network element receiving a second data network access identifier of a first terminal from a first network element. The second network element then re-selects an edge application server for the first terminal based on the second data network access identifier.

[0037] In possible implementations, the method provided in this embodiment of the Application may further include a second network element transmitting a member list of the first set of terminals (including the identification information of one or more terminals and the identification information of the first terminal).

[0038] In possible implementations, the method provided in this embodiment of the Application may further include a second network element determining that the first terminal has been disassociated from the first set of terminals.

[0039] In a possible implementation, the method provided in this embodiment of the Application may further include, when it is determined that the first terminal has been disassociated from the first set of terminals, the second network element transmitting an updated member list of the first set of terminals (which includes the identification information of one or more terminals, but does not include the identification information of the first terminal).

[0040] Optionally, the second network element may further transmit a service identifier, a traffic correlation identifier, and instruction information for the first edge application server or a first data network access identifier.

[0041] For example, a second network element may transmit to a policy control network element (e.g., a PCF network element) the member list of the first terminal set, service identifiers, traffic correlation identifiers, and instruction information for the first edge application server or the first data network access identifier. For example, if the second network element determines that the first terminal has been disassociated from the first terminal set, the second network element may transmit to the policy control network element (e.g., a PCF network element) the updated member list of the first terminal set, service identifiers, traffic correlation identifiers, and instruction information for the first edge application server or the first data network access identifier.

[0042] In possible implementations, the method provided in this embodiment of the Application may further include the second network element transmitting edge application server address substitution information to the first network element.

[0043] According to a fourth aspect, one embodiment of the present invention is a communication method comprising a first terminal receiving first instruction information from a first network element. The first terminal re-selects an edge application server for the first terminal based on the first instruction information.

[0044] In possible implementations, the method provided in this embodiment of the Application may further include the first terminal clearing the Domain Name System cache based on the first instruction information.

[0045] In possible implementations, the method provided in this embodiment of the Application may further include a first terminal receiving instruction information from a first network element to instruct it to clear the Domain Name System cache. Based on the instruction information to clear the Domain Name System cache, the first terminal clears the Domain Name System cache.

[0046] According to a fifth aspect, one embodiment of the present application provides a communication method in which a first network element receives a third message, the third message is used by the first network element to determine that it will provide a second data network access identifier of a first terminal to a second network element. The first network element transmits the second data network access identifier of the first terminal to the second network element.

[0047] For example, the third message may contain fifth directive information. The fifth directive information is used to request the second data network access identifier of the first terminal. Alternatively, the directive information contained in the fifth message may indicate that the first terminal has been disassociated from the first terminal set.

[0048] In possible implementations, the method provided in this embodiment of the Application may further include the first network element determining a second data network access identifier.

[0049] In possible implementations, the method provided in this embodiment of the Application may further include the first network element receiving edge application server address substitution information from the first network element.

[0050] In possible implementations, the method provided in this embodiment of the Application may further include the first network element receiving edge application server relocation-related information from the first network element.

[0051] Optionally, the first network element receives a service identifier from the first network element.

[0052] According to the sixth aspect, one embodiment of the present application provides a communication device. The communication device can implement the method in the first aspect or any one of the possible implementations of the first aspect. Thus, beneficial effects in either the first aspect or any one of the possible implementations of the first aspect can also be achieved. The communication device may be a first network element, or a device that supports the first network element when implementing the method in either the first aspect or any one of the possible implementations of the first aspect, for example, a chip used in the first network element. The communication device may implement the aforementioned method by software, hardware, or hardware running the corresponding software.

[0053] In one example, the communication device may include a processing unit and a communication unit. The communication unit is configured to perform receive / transmit related steps performed by a first network element in either the first aspect or a possible implementation of the first aspect. The processing unit is configured to perform processing related steps performed by a first network element in either the first aspect or a possible implementation of the first aspect.

[0054] For example, if the communication device is a chip or chip system within the first network element, the processing unit may be a processor and the communication unit may be a communication interface. For example, the communication interface may be an input / output interface, pins, a circuit, etc. The processing unit executes instructions stored in the memory unit, enabling the first network element to implement the communication method described in either the first aspect or any possible implementation of the first aspect. The memory unit may be a memory unit within the chip (e.g., a register or cache) or a memory unit located within the first network element but outside the chip (e.g., read-only memory or random access memory).

[0055] According to the seventh aspect, one embodiment of the present application provides a communication device. The communication device may implement the method in the second aspect or one of the possible implementations of the second aspect. Thus, beneficial effects in the second aspect or one of the possible implementations of the second aspect may also be achieved. The communication device may be a second network element, or a device that supports the second network element when implementing the method in the second aspect or one of the possible implementations of the second aspect, for example, a chip used in the second network element. The communication device may implement the aforementioned method by software, hardware, or hardware running the corresponding software.

[0056] In one example, the communication device may include a processing unit and a communication unit. The communication unit is configured to perform receive / transmit related steps performed by the second network element in either the second aspect or one of the possible implementations of the second aspect. The processing unit is configured to perform processing related steps performed by the second network element in either the second aspect or one of the possible implementations of the second aspect.

[0057] For example, if the communication device is a chip or chip system within the second network element, the processing unit may be a processor and the communication unit may be a communication interface. For example, the communication interface may be an input / output interface, pins, a circuit, etc. The processing unit executes instructions stored in the memory unit, enabling the second network element to implement the communication method described in either the second aspect or any possible implementation of the second aspect. The memory unit may be a memory unit within a chip (e.g., a register or cache) or a memory unit located within the second network element and outside the chip (e.g., read-only memory or random-access memory).

[0058] According to the eighth aspect, one embodiment of the present application provides a communication device. The communication device may implement the method in the third aspect or one of the possible implementations of the third aspect. Thus, beneficial effects in the third aspect or one of the possible implementations of the third aspect may also be achieved. The communication device may be a third network element, or a device that supports the third network element when implementing the method in the third aspect or one of the possible implementations of the third aspect, for example, a chip used in the third network element. The communication device may implement the aforementioned method by software, hardware, or hardware running the corresponding software.

[0059] In one example, the communication device may include a processing unit and a communication unit. The communication unit is configured to perform receive / transmit related steps performed by a third network element in either the third aspect or a possible implementation of the third aspect. The processing unit is configured to perform processing related steps performed by a third network element in either the third aspect or a possible implementation of the third aspect.

[0060] For example, if the communication device is a chip or chip system within the third network element, the processing unit may be a processor, and the communication unit may be a communication interface. For example, the communication interface may be an input / output interface, pins, a circuit, etc. The processing unit executes instructions stored in the memory unit, enabling the third network element to implement the communication method described in the third aspect or any one of the possible implementations of the third aspect. The memory unit may be a memory unit within the chip (e.g., a register or cache), or a memory unit located within the third network element and outside the chip (e.g., read-only memory or random access memory).

[0061] According to the ninth aspect, one embodiment of the present application provides a communication device. The communication device may implement the method in the fourth aspect or one of the possible implementations of the fourth aspect. Thus, beneficial effects in the fourth aspect or one of the possible implementations of the fourth aspect may also be achieved. The communication device may be a first terminal, or a device that supports the first terminal when implementing the method in the fourth aspect or one of the possible implementations of the fourth aspect, for example, a chip used in the first terminal. The communication device may implement the method described above by software, hardware, or hardware running the corresponding software.

[0062] In one example, the communication device may include a processing unit and a communication unit. The communication unit is configured to perform receiving / transmitting related steps performed by a first terminal in either the fourth aspect or one of the possible implementations of the fourth aspect. The processing unit is configured to perform processing related steps performed by a first terminal in either the fourth aspect or one of the possible implementations of the fourth aspect.

[0063] For example, if the communication device is a chip or chip system within the first terminal, the processing unit may be a processor, and the communication unit may be a communication interface. For example, the communication interface may be an input / output interface, pins, a circuit, etc. The processing unit executes instructions stored in the memory unit to enable the first terminal to implement the communication method described in the fourth aspect or any one of the possible implementations of the fourth aspect. The memory unit may be a memory unit within a chip (e.g., a register or a cache), or a memory unit located within the first terminal but outside the chip (e.g., read-only memory or random access memory).

[0064] According to the tenth aspect, one embodiment of the present application provides a communication device. The communication device may implement the method in the fifth aspect or one of the possible implementations of the fifth aspect. Thus, beneficial effects in the fifth aspect or one of the possible implementations of the fifth aspect may also be achieved. The communication device may be a first network element, or a device that supports the first network element when implementing the method in the fifth aspect or one of the possible implementations of the fifth aspect, for example, a chip used in the first network element. The communication device may implement the aforementioned method by software, hardware, or hardware running the corresponding software.

[0065] In one example, the communication device may include a processing unit and a communication unit. The communication unit is configured to perform receive / transmit related steps performed by the first network element in either the fifth aspect or a possible implementation of the fifth aspect. The processing unit is configured to perform processing related steps performed by the first network element in either the fifth aspect or a possible implementation of the fifth aspect.

[0066] For example, if the communication device is a chip or chip system within the first network element, the processing unit may be a processor and the communication unit may be a communication interface. For example, the communication interface may be an input / output interface, pins, a circuit, etc. The processing unit executes instructions stored in the memory unit, enabling the first network element to implement the communication method described in the fifth aspect or any one of the possible implementations of the fifth aspect. The memory unit may be a memory unit within a chip (e.g., a register or a cache) or a memory unit located within the first network element but outside the chip (e.g., read-only memory or random-access memory).

[0067] According to the eleventh aspect, the present invention provides a first network element including a processor, the processor being connected to memory. The processor reads instructions stored in memory, enabling the first network element to perform the method in the first aspect or any one of the designs of the first aspect. The first network element may further include memory. Optionally, the first network element may further include a communication interface.

[0068] According to the twelfth aspect, the present invention provides a second network element including a processor, the processor being connected to memory. The processor reads instructions stored in memory, enabling the second network element to perform the method in either the second aspect or any one of the designs of the second aspect. The second network element may further include memory. Optionally, the second network element may further include a communication interface.

[0069] According to the thirteenth aspect, the present invention provides a communication system comprising a first network element and a target device, wherein the target device is either a first terminal or a second network element. The first network element performs a method in any one of the first aspect or a possible implementation thereof, the second network element performs a method in any one of the third aspect or a possible implementation thereof, and the first terminal performs a method in any one of the fourth aspect or a possible implementation thereof.

[0070] According to the fourteenth aspect, the present application provides a communication system comprising a second network element and a first network element. The second network element performs a method in either the second aspect or a possible implementation of the second aspect, and the first network element performs a method in either the fifth aspect or a possible implementation of the fifth aspect.

[0071] According to the fifteenth aspect, the present invention provides a computer-readable storage medium containing computer-readable instructions. When the instructions are executed on a computer, the computer is able to perform the method in the first aspect or in any one of the possible implementations of the first aspect.

[0072] According to the sixteenth aspect, the present invention provides a computer-readable storage medium containing computer-readable instructions. When the instructions are executed on a computer, the computer is able to perform the method in the second aspect or in any one of the possible implementations of the second aspect.

[0073] According to the 17th aspect, the present application provides a computer program product including a computer program. When the program is executed on a computer, the computer becomes capable of doing the method in the first aspect or any one of the possible implementations of the first aspect.

[0074] According to the eighteenth aspect, the present application provides a computer program product including a computer program. When the program is executed on a computer, the computer becomes capable of doing the method in the second aspect or in any one of the possible implementations of the second aspect.

[0075] According to the 19th aspect, the present application provides a chip for use in a first network element. The chip includes at least one processor and a communication interface. The communication interface is coupled to at least one processor. The processor is configured to execute computer programs or instructions to perform the method in the first aspect or any one of the possible implementations of the first aspect. The communication interface is configured to communicate with other modules outside the chip.

[0076] According to the 20th aspect, the present application provides a chip for use in a second network element. The chip includes at least one processor and a communication interface. The communication interface is coupled to at least one processor. The processor is configured to execute computer programs or instructions to perform the method in the second aspect or any one of the possible implementations of the second aspect. The communication interface is configured to communicate with other modules outside the chip. [Brief explanation of the drawing]

[0077] [Figure 1] This figure shows the architecture of the communication system according to the embodiment of the present invention.

[0078] [Figure 2] This figure shows a 5G network architecture according to an embodiment of the present invention.

[0079] [Figure 3] This is a flowchart illustrating how a terminal according to an embodiment of the present invention accesses an edge application server.

[0080] [Figure 4] This is a flowchart of the communication method according to the embodiment of the present invention.

[0081] [Figure 5] This is a flowchart of another communication method according to the embodiment of the present invention.

[0082] [Figure 6] This is a first schematic flowchart of the communication method according to the embodiment of the present invention.

[0083] [Figure 7] This is a second schematic flowchart of the communication method according to the embodiment of the present invention.

[0084] [Figure 8] This is a third schematic flowchart of the communication method according to the embodiment of the present invention.

[0085] [Figure 9] This is a fourth schematic flowchart of the communication method according to the embodiment of the present invention.

[0086] [Figure 10] This figure shows the structure of a communication device according to an embodiment of the present invention.

[0087] [Figure 11] This figure shows the hardware structure according to an embodiment of the present invention.

[0088] [Figure 12] This figure shows the structure of a chip according to the present embodiment. [Modes for carrying out the invention]

[0089] To clearly illustrate the technical solutions in the embodiments of this application, the terms “first” and “second” are used in the embodiments of this application to distinguish the same or similar items that provide essentially the same function or purpose. For example, “first instruction information” and “second instruction information” are used merely to distinguish different instruction information and do not limit the order of the first and second instruction information. A person skilled in the art will understand that the terms “first” and “second” do not limit the quantity or order of execution and that the terms “first” and “second” do not indicate a clear distinction.

[0090] In this application, the terms “example” or “for example” are used to indicate that an example, illustration, or explanation is being given. No embodiment or design scheme described as “example” or “for example” in this application should be described as being preferable to or having more advantages than other embodiments or design schemes. More precisely, the use of the terms “example” or “for example” is intended to present relative concepts in a specific way.

[0091] In this application, "at least one" means one or more, and "plural" means two or more. The words "and / or" describe the relationship between related objects and indicate that three relationships may exist. For example, A and / or B may mean the following cases: only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. The letter " / " generally indicates an "or" relationship between related objects. "At least one of the following items" or a similar expression means any combination of these items, including any single item or any combination of multiple items. For example, at least one item of a, b, or c may mean a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

[0092] The system architectures and service scenarios described in the embodiments of this application are intended to more clearly illustrate the technical solutions in the embodiments of this application and do not constitute a limitation on the technical solutions provided in the embodiments of this application. Those skilled in the art will know that, with the evolution of network architectures and the emergence of new service scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems. In the embodiments of this application, examples are used for illustrative purposes in which the methods provided are applied to NR systems or 5th generation mobile communication technology (5th generation mobile networks or 5th generation wireless systems, 5th-Generation, 5G) networks.

[0093] Figure 1 shows the architecture of a communication system according to an embodiment of the present invention. The system includes a session management network element 100, an application network element 200, one or more terminals (such as terminal 301, terminal 302, ..., and terminal 30n), and one or more edge application servers (such as edge application server 401 and edge application server 402).

[0094] One or more services are deployed on each edge application server, and terminals can access the services deployed on the edge application servers. It is also clear that terminals can receive service data flows sent by the edge application servers. For example, various services such as game services, session services, and multimedia services may be deployed on the edge application servers.

[0095] The application network element 200 is configured to interact with the session management network element 100 to provide services, information, and so on.

[0096] Optionally, as shown in Figure 1, when multiple terminals need to access a service deployed on the same edge application server, the multiple terminals may be grouped into a terminal set 500, and the multiple terminals access the same edge application server (e.g., edge application server 401). For example, edge application server 401 may be referred to as a common EAS. The common EAS can be understood as the edge application server corresponding to terminal set 500. Alternatively, the same DNAI may be accessed, where the DNAI may be referred to as a common DNAI.

[0097] Members of terminal set 500 that need to access the edge application server 401 are constrained by a set or list of terminal identifiers (UE list) within terminal set 500, by a group identifier (group ID), or by the identifier of all terminals (any UE ID).

[0098] Optionally, a spatial validity condition may be used to further restrict the terminal set 500. Specifically, terminal 300 belongs to terminal set 500 if it is in the UE list / group ID / any UE ID and its location is within the location range identified by the spatial validity condition.

[0099] The communication system shown in Figure 1 can be applied to the fifth-generation (5G) network architecture shown in Figure 2. It is clear that the communication system can also be applied to future network architectures, such as the sixth-generation (6G) network architecture. This is not limited to the present invention.

[0100] For example, the communication system shown in Figure 1 is applied to a 5G network architecture. Figure 2 shows a 5G network architecture based on a point-to-point interface. The network element or entity corresponding to the session management network element 100 in Figure 1 may be a session management function (SMF) network element in the 5G network architecture shown in Figure 2. The network element or entity corresponding to the application network element 200 in Figure 1 may be an application function (AF) network element in the 5G network architecture shown in Figure 2. The network element or entity corresponding to the terminal 300 in Figure 1 may be user equipment (UE) in the 5G network architecture shown in Figure 2.

[0101] In addition, as shown in Figure 2, the 5G network architecture may further include network repository function (NRF) network elements, policy control function (PCF) network elements, access and mobility management function (AMF) network elements, network exposure function (NEF) network elements, unified data function (UDM) network elements, edge application server discovery function (EASDF) network elements, access network (AN), user plane function (UPF) network elements, data network (DN), edge application server (EAS), and the like. This is not particularly limited to the embodiments of the present invention.

[0102] The following describes the functions of the network elements.

[0103] An NRF network element may be configured to provide network element discovery functionality and, based on requests from other network elements, provide network element information corresponding to the network element type. The NRF network element may further provide network element management services, such as network element registration, updating, and unregistration, as well as network element status subscriptions and pushes.

[0104] The PCF network element is primarily responsible for supporting unified policies to manage network behavior and providing policy rules for control plane functionality for implementation. For policy decisions, it mainly retrieves subscription-related information from the Unified Data Repository (UDR) network element. The UDR provides the ability to store subscription data, policy data, and capability exposure-related data.

[0105] AF network elements are primarily responsible for interacting with the core network to provide services, such as influencing traffic routing, accessing network capability exposures, interacting with policy decision network elements for policy control, and providing information to the core network.

[0106] An AF network element may be a third-party functional entity, or it may be an operator-deployed application service, such as an IP Multimedia Subsystem (IMS) voice call service. An AF network element may be referred to as an application server.

[0107] The UDM network element is primarily responsible for user subscription management, access authorization, and authentication information generation.

[0108] AMF network elements primarily perform functions such as mobility management and access authentication or authorization. In addition, AMF network elements are further responsible for the transfer of user policies between terminals and PCF network elements. SMF network elements are primarily responsible for session management in the network architecture, and their functions mainly include session establishment, modification, and release. For example, a session management network element may assign an IP address to a terminal or select a UPF to provide packet forwarding functionality.

[0109] SMF network elements primarily perform functions such as session management, execution of control policies distributed by PCF network elements, selection of UPF network elements, and assignment of Internet Protocol (IP) addresses to terminals.

[0110] NEF network elements are primarily configured to support the disclosure of capabilities and events.

[0111] The EASDF network element is primarily responsible for assisting EAS discovery and is mainly configured to process Domain Name System (DNS) messages based on SMF instructions. This processing includes reporting DNS messages to the SMF, adding extension mechanisms for DNS client subnet options (EDNS) to the DNS cache, forwarding the DNS cache to the DNS server, and forwarding DNS responses to the UE.

[0112] UPF network elements are used as interfaces to the data network and implement functions such as user plane data transfer, session / flow level billing statistics collection, and bandwidth limiting. Refer to the network architecture shown in Figure 2. UPFs directly connected to the DN are called protocol data unit session anchors (PSAs), with central session anchors (C-PSAs) connecting to the central data network and local session anchors (L-PSAs) connecting to the local data network. UPF network elements not connected to the DN are uplink classifier (UL CL) UPF anchors or branching point (BP) UPF anchors.

[0113] A DN (Data Network) is a network located outside the operator network. The operator network may access multiple DNs, and multiple services may be deployed on the DNs to provide services such as data and / or voice to terminal devices. For example, a DN could be the private network of a smart factory, where sensors installed in the smart factory's workshops are terminal devices, and a control server for the sensors is deployed on the DN, providing services to the sensors. The sensors could communicate with the control server to receive commands from the server and, according to those commands, transmit collected sensor data to the control server. In another example, a DN could be a company's internal office network, where employees' mobile phones or computers are terminal devices, and these can access information, data resources, etc., within the company's internal office network. DNs are classified into central DNs and local part of DNs. As shown in Figure 2, a local data network includes multiple EASs (Environmental Agencies).

[0114] In Figure 2, the terminal accesses the network via an AN device, and the terminal communicates with AMF network elements via the N1 interface (abbreviated as N1). The SMF network element communicates with one or more UPF network elements via the N4 interface (abbreviated as N4). The UPF network element communicates with DN via the N6 interface (abbreviated as N6). The AN device communicates with AMF network elements via the N2 interface (abbreviated as N2). The AN device communicates with UPF network elements via the N3 interface (abbreviated as N3). The UPF network elements communicate with each other via the N9 interface (abbreviated as N9).

[0115] Control plane network elements can also interact with each other via service-based interfaces. For example, as shown in Figure 2, AMF, SMF, UDM, or PCF network elements interact with each other via service-based interfaces. For example, the service-based interface represented by an AMF network element may be Namf. The service-based interface represented by an SMF network element may be Nsmf. The service-based interface represented by a UDM network element may be Nudm. The service-based interface represented by a PCF network element may be Npcf. The service-based interface represented by an NEF network element may be Nnef. The service-based interface represented by an AF network element may be Naf. The service-based interface represented by an NRF network element may be Nnrf. For relevant explanations of the names of the various service-based interfaces, please refer to the diagram of the 5G system architecture in the prior art. Further details are not provided herein.

[0116] It should be noted that Figure 2 provides only one example of an SMF network element. It is clear that Figure 2 may include multiple SMF network elements, for example, SMF network element 1 and SMF network element 2. This is not particularly limited in these embodiments of the present application.

[0117] It should be noted that the AN device, AMF network element, SMF network element, UDM network element, UPF network element, PCF network element, etc., in Figure 2 are merely names and do not constitute any limitation to the device. In 5G networks and other future networks, the network elements or entities corresponding to the AN device, AMF network element, SMF network element, UDM network element, UPF network element, and PCF network element may have other names. This is not particularly limited in the embodiments of this application. For example, the UDM network element may be replaced with a home subscriber server (HSS), a user subscription database (USD), a database entity, etc. This is described uniformly in this specification and will not be described in detail thereafter.

[0118] In Figure 2, Nausf, Nnef, Npcf, Nudm, Naf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface sequence numbers. For the meaning of interface sequence numbers, please refer to the meanings defined in the 3GPP standard protocol, which are not limited herein.

[0119] It can be understood that the aforementioned network elements or functions may be network elements within a hardware device, software functions running on dedicated hardware, or virtualization functions instantiated on a platform (e.g., a cloud platform).

[0120] Optionally, a network element or function may be implemented by a single device, jointly implemented by multiple devices, or as a functional module within a single device. This is not particularly limited in the embodiments of this application. The session management network element 100 and the application network element 200 in this application may be an SMF network element and an AF network element in Figure 2, respectively, or network elements having the functions of an SMF network element and an AF network element in a future communication network such as a 6G network. This is not limited in this application. For ease of explanation, an example in which the session management network element 100 and the application network element 200 are an SMF network element and an AF network element, respectively, is used for the explanation in this application.

[0121] User equipment (UE) is a device that enables a user to access network services. According to the 3GPP standard, the interface between user equipment and the network is a wireless interface.

[0122] UE may include various handheld devices, in-vehicle devices, wearable devices, and computing devices having wireless communication capabilities, or other processing devices connected to a wireless modem. UE may further include subscriber units, cellular phones, smartphones, wireless data cards, personal digital assistant (PDA) computers, tablet computers, wireless modems, handheld devices, laptop computers, cordless phones, wireless local loop (WLL) stations, machine type communication (MTC) terminals, user equipment (UE), mobile stations (MS), terminal devices, relay user equipment, etc. Relay user equipment may, for example, be a 5G residential gateway (RG). For ease of explanation, the user equipment described above is collectively referred to as a terminal in this application.

[0123] It should be understood that the terminals in the embodiments of this application may be terminal devices in the Internet of Things, or terminals in multiple vertical industrial application areas such as ports, intelligent factories, rail transport, logistics, unmanned aerial vehicles, and unmanned vehicles, such as control devices and sensors on mobile robots, automated guided vehicles (AGVs), unmanned vehicles, trains, or control devices and sensors deployed in factories.

[0124] In some related technologies, when a terminal needs to access a service, in edge computing (EC) scenarios, the terminal needs to access the EAS (Environmental Application Server) that is closest to the terminal and capable of providing the service, and provide the EAS with its Internet Protocol (IP) address. After obtaining the EAS's IP address, the terminal accesses the EAS. Figure 3 is a schematic flowchart of how a terminal accesses an edge application server. Referring to the network architecture shown in Figure 2, the specific steps are as follows:

[0125] Step 1: The terminal first establishes a protocol data unit (PDU) session. Steps 2 and 3 below are performed during the PDU session establishment procedure.

[0126] Step 2: Select the EASDF network element from the SMF network element.

[0127] Step 3: The SMF network element sends Domain Name System (DNS) processing rules to the EASDF network element, and the DNS processing rules are used by the EASDF network element to process DNS messages.

[0128] Step 4: The SMF network element updates its DNS processing rules based on a change in the EAS deployment status or other reasons (e.g., a change in the EAS address), and may retransmit, for example, the new address of the EASDF network element or the new location of the EASDF network element.

[0129] Step 5: The terminal sends a DNS query message to the EASDF network element, and the DNS query message includes a fully qualified domain name (FQDN).

[0130] Step 6: The EASDF network element matches the FQDN in the DNS query message against the DNS processing rule. If the FQDN matches the location in EAS, this indicates a successful match, and the EASDF network element reports the FQDN to the SMF network element.

[0131] Step 7: The SMF network element returns to the EASDF network element the "information necessary to determine the EDNS client subnet option" or the address of the local DNS server, based on the FQDN and the terminal's location.

[0132] Step 8: The EASDF network element sends a DNS query message to DNS, determines the EDNS client subnet option based on the "information required to determine the EDNS client subnet option", adds the EDNS client subnet option to the DNS query message, and forwards the DNS query message to the central DNS server, or the EASDF network element forwards the DNS query message to the local DNS server.

[0133] Step 9: The DNS server returns a DNS response to the EASDF network element, and the DNS response contains the IP address of the EAS.

[0134] Step 10: The EASDF network element matches the EAS's IP address in the DNS response against the DNS processing rule. If the match is successful, it caches the DNS response and reports the EAS's IP address to the SMF network element.

[0135] Step 11: The SMF network element inserts a traffic offload point based on the EAS's IP address and configures the traffic offload rule.

[0136] Step 12: The SMF network element instructs the EASDF network element to forward the DNS response to the terminal.

[0137] Step 13: The EASDF network element forwards the DNS response to the terminal.

[0138] When a terminal moves, for example, when the distance between the terminal and the EAS increases, or when the EAS currently being accessed by the terminal is overloaded, the EAS may become unsuitable to serve the terminal. In this case, network elements in the core network may decide to trigger EAS rediscovery based on the terminal's movement or load balancing. For example, an SMF network element may send a PDU session change command to the terminal based on a change in the terminal's data network access identifier (DNAI) or local session anchor (L-PSA), and the PDU session change command includes EAS rediscovery instruction information. The PDU session change command may further include a scope (e.g., a fully qualified domain name (FQDN) that is in the domain name system (DNS) cache and needs to be cleared). After receiving the PDU session change command, the terminal clears its DNS cache. If the PDU session change command includes a scope, the terminal clears only the DNS cache related to the scope (e.g., the FQDN).

[0139] In some other related technologies, after a terminal moves, the terminal accesses the EAS again, with the EAS accessed by the terminal before the move being referred to as the source EAS, and the EAS accessed after the move being referred to as the target EAS. Specifically, the EAS IP substitution method is used for implementation, i.e., when a terminal moves, an SMF network element is triggered to send a DNAI to an AF network element, and the AF network element selects a target EAS based on the DNAI, or the AF network element decides to select a target EAS based on load balancing. After selecting a target EAS, the AF network element copies the context of the terminal running on the source EAS (e.g., role status in an ongoing game, and progress of a video being watched) to the target EAS. The AF network element then sends EAS IP substitution information to the SMF network element, which includes the IP address and port number of the source EAS and the IP address and port number of the target EAS. After receiving EAS IP substitution information, the SMF network element configures an L-PSA accordingly, and then the L-PSA performs EAS IP substitution based on the instructions of the SMF network element.

[0140] Currently, in some EC scenarios, terminals within a terminal set need to access the same EAS (which may be referred to as a common EAS) or the same DNAI (which may be referred to as a common DNAI). However, it can be understood that each terminal within a terminal set is dynamic, and terminals can join or leave the terminal set at any time. However, a terminal (e.g., terminal A) may leave the terminal set because, when terminal A accesses the common EAS or common DNAI, the EAS corresponding to the common EAS or common DNAI is not suitable for serving terminal A, for example, the common EAS is far from terminal A. "Not suitable for serving terminal A" as used herein may mean that the EAS or DNAI is far from terminal A's current location, does not correspond to terminal A's DNAI, or has a high load, the UPF corresponding to the EAS or DNAI is different from the UPF corresponding to the UE's location, or there is an EAS or DNAI that is closer to terminal A's current location or has a lower load. When terminal A leaves the terminal cluster, it loses the constraints of common EAS or common DNAI, and terminal A can choose a better EAS. In this way, terminal A's latency can be reduced, and the user experience can be improved. However, conventional technologies do not have an edge migration solution to use after a terminal leaves the terminal cluster.

[0141] Note that a terminal leaving a terminal set means that the terminal changes from a state of belonging to the terminal set to a state of not belonging to the terminal set, or that the terminal no longer needs to access the common EAS or common DNAI with other terminals in the terminal set. A terminal leaving a terminal set may refer to the moment of the state change, the state after the change, or the state change event. After a terminal leaves a terminal set, the terminal may not belong to any terminal set, or may join another terminal set. This is not limited to the present application. A terminal leaving a terminal set can be described as follows: The terminal is disassociated from the terminal set, the terminal no longer belongs to the terminal set, or the terminal no longer needs to access the (current / original) common EAS / common DNAI. Note that access to a data network access identifier may refer to access to the data network identified by the data network access identifier, or access to services via the data network or user plane identified by the data network access identifier.

[0142] Based on this, one embodiment of the present invention provides a communication method. In this method, EAS rediscovery instruction information is triggered based on a terminal leaving a terminal set, thereby selecting an EAS suitable for providing services to the terminal through EAS rediscovery when the terminal leaves the terminal set.

[0143] In embodiments of the present application, the specific structure of an entity for performing a communication method is not particularly limited in embodiments of the present application, provided that the entity can perform communication according to the communication method in embodiments of the present application by executing a program that records code for performing the communication method in embodiments of the present application. For example, the communication method provided in embodiments of the present application can be performed by calling a program and can be performed by a functional module in a first network element, or by a communication device used in the first network element, such as a chip, chip system, or integrated circuit. The chip, chip system, or integrated circuit may be located within the first network element or independent of the first network element. This is not limited to embodiments of the present application.

[0144] Refer to Figure 4. One embodiment of the present invention provides a communication method. This method includes the following steps.

[0145] Step 401: The first network element determines that the first terminal has been disassociated from the first terminal set.

[0146] For example, the first terminal set includes one or more terminals, and one or more terminals access a first edge application server or a first data network access identifier. It can be understood that before the first terminal is disassociated from the first terminal set, the first terminal set includes one or more terminals and the first terminal. After the first terminal is disassociated from the first terminal set, the first terminal set includes one or more terminals.

[0147] For example, the disassociation of a first terminal from a first terminal set may also be referred to as the first terminal leaving the first terminal set. The disassociation of a first terminal from a first terminal set can be understood as follows: The first terminal no longer needs to access the same EAS (e.g., the first edge application server) or the same DNAI (e.g., the first data network access identifier) ​​as other terminals in the first terminal set. The disassociation process is a state change in which the first terminal changes from belonging to the first terminal set to no longer belonging to the first terminal set. In embodiments of the present application, the first terminal set may also be referred to as the first terminal group.

[0148] It can be understood that before the first terminal is disassociated from the first terminal set, the first terminal belongs to the first terminal set, or in other words, the first terminal and other terminals in the first terminal set have access to a common EAS (i.e., the first edge application server) or a common DNAI (i.e., the first data network access identifier).

[0149] For example, common EAS may provide one or more services. Before the first terminal is disassociated from the first terminal set, the first terminal and other terminals in the first terminal set access common EAS to access the services provided by common EAS.

[0150] Referring to Figure 1, the first network element in the embodiment of the present invention may be the session management network element 100 shown in Figure 1. The first terminal may be any of the terminals shown in Figure 1. The first terminal set may be the terminal set 500 shown in Figure 1. The first edge application server in the embodiment of the present invention may be an edge application server 401 accessed by the multiple terminals shown in Figure 1.

[0151] For example, the first edge application server is common EAS, and the service deployed on common EAS is game A. Game A is an online game. In online mode, each room in the game may support online interaction for up to 10 users. When 10 users in room 1 are playing the game, the terminals corresponding to the users belong to the first set of terminals, which includes the first terminal. In this case, the 10 terminals in room 1 access common EAS. When the user corresponding to the first terminal leaves room 1, for example, the user may start playing in single-player mode, join another game room, or leave game A, the first terminal no longer needs to access the same EAS as the other users in room 1, i.e., it no longer needs to access common EAS. In this case, the first terminal is disassociated from the first set of terminals.

[0152] In this embodiment of the present application, please refer to the embodiment shown in Figure 3 for the specific process by which any terminal in the first terminal set accesses the common EAS or common DNAI. Further details will not be described again herein.

[0153] In one example, the first network element is an SMF network element. Access to the common EAS by multiple terminals within the first terminal set specifically occurs when the SMF network element receives policy and charging control (PCC) rules, which are generated using a Traffic Correlation ID, a service identifier, and common EAS directive information. The Traffic Correlation ID is the identifier of the first terminal set; the service identifier indicates that terminals within the first terminal set must access the same data network access identifier when accessing a service; and the common EAS directive information indicates that terminals within the first terminal set must access the same data network access identifier. The SMF network element determines the Traffic Correlation ID of the first terminal set. If the first terminal set already has a common EAS that can be accessed, the SMF network element sends the common EAS identification information (e.g., address) to the EASDF network element. Optionally, an SMF network element may further instruct an EASDF network element to return a DNS response to the terminal containing the address of a common EAS. If the first set of terminals does not have a common EAS that can be accessed, the SMF network element must first determine a common EAS corresponding to the first set of terminals. For example, if the SMF network element can receive an EAS address from the EASDF network element, the SMF network element will use the EAS provided by the EASDF network element as the common EAS.

[0154] A service identifier can be a service data flow (SDF), an application identifier (App ID), or a fully qualified domain name (FQDN).

[0155] In another example, the first network element is an SMF network element. When one or more terminals in the first terminal set access a common DNAI, specifically, the SMF network element receives a PCC rule, which contains a traffic correlation ID, a service identifier, and a common DNAI directive. The common DNAI directive indicates that terminals in the first terminal set need to access the same data network access identifier. If the SMF network element determines that the FQDN reported by the EASDF network element matches the service ID in the PCC rule and that the FQDN and / or service ID have a corresponding common DNAI, then the SMF network element determines that the terminals need to access the common DNAI corresponding to the first terminal set. If the first terminal set already has a corresponding common DNAI, the SMF network element determines the EDNS client subnet option or local DNS server address based on the common DNAI and sends the address of the EDNS client subnet option or local DNS server corresponding to the common DNAI to the EASDF network element. If the first set of terminals does not have a corresponding common DNAI, the SMF network element first determines the common DNAI, then determines the EDNS client subnet option or the address of the local DNS server, and sends the address of the EDNS client subnet option or local DNS server that corresponds to the common DNAI to the EASDF network element.

[0156] Step 402: The first network element transmits the second data network access identifier of the first terminal to the second network element, or transmits the first instruction information to the first terminal. In response, the second network element receives the second data network access identifier of the first terminal from the first network element, or the first terminal receives the first instruction information from the first network element.

[0157] For example, the first instruction information is used to trigger the re-selection of an edge application server for the first terminal. For example, the first instruction information is related to the rediscovery of an edge application server. For example, the first instruction information is edge application server rediscovery related instruction information.

[0158] The second data network access identifier represents the current location of the first terminal. When the first terminal does not leave the first terminal set, the data network access identifier corresponding to the common EAS or the common DNAI accessed by the first terminal set is the result of a compromise by multiple terminals within the first terminal set. Therefore, the DNAI is not necessarily optimal for the first terminal. After the first terminal leaves the first terminal set, the first terminal is free to choose which edge application server to access.

[0159] In one example, the first instruction information may be carried in a PDU session modification / update instruction. For example, the first instruction information may be edge application server rediscovery instruction information.

[0160] Optionally, the first instruction information may be transmitted to the first terminal together with a service identifier, or the PDU session change / update instruction may further include a service identifier to indicate that the first terminal needs to perform EAS rediscovery when accessing the service indicated by the service identifier, or to indicate to the first terminal to clear or refresh cached edge application server information (e.g., DNS cache).

[0161] For example, the first network element is an SMF network element. When the SMF network element determines that the first terminal has been disassociated from the first terminal set, the SMF network element sends a PDU session change / update command to the first terminal.

[0162] Step 403a: The second network element selects a second edge application server based on the second data network access identifier of the first terminal. The second edge application server is an edge application server suitable for providing services to the first terminal.

[0163] Step 403b: The first terminal re-selects an edge application server for the first terminal based on the first instruction information.

[0164] For example, please refer to the embodiment shown in Figure 3 for a specific implementation of step 403b. Further details will not be described again in this specification.

[0165] In the aforementioned communication method, the first network element determines that the first terminal has been disassociated from the first terminal set, and then the first network element sends the second data network access identifier of the first terminal to the second network element, or sends edge application server rediscovery related instruction information to the first terminal, thereby triggering the second network element to select an edge application server suitable for providing services for the first terminal, or triggering the first terminal to perform edge application server rediscovery in order to select an edge application server suitable for providing services. In this solution, the first terminal may trigger an edge application server migration to select a better edge application server for the first terminal after the first network element has determined that the first terminal has left the first terminal set. In this way, latency for the first terminal can be reduced and the user experience can be improved.

[0166] In some embodiments of the present application, the first network element may further instruct the first terminal to clear the Domain Name System cache. For example, the first instruction information further instructs the first terminal to clear the Domain Name System cache. In other examples, in addition to sending the first instruction information, the first network element may further send Domain Name System clear instruction information, which is described as instructing the first terminal to clear the Domain Name System cache or to clear or refresh cached edge application server information.

[0167] Domain name system cache (DNS cache) refers to the process where a first device stores the query results (e.g., the IP address of the DNS server) for a certain period after querying the DNS. This stored information is called the DNS cache. The storage period is called the time to live (TTL).

[0168] For example, if the TTL of a DNS cache has not expired, and the first terminal needs to access the service for the FQDN corresponding to the DNS cache whose TTL has not expired, the first terminal will either use the DNS cache directly as the query result, or the first terminal will access the IP address corresponding to the corresponding DNS cache without querying DNS. If the edge application server rediscovery-related instruction information includes a scope (e.g., FQDN), the first terminal will clear only the DNS cache related to that scope.

[0169] Optionally, if the first instruction information includes a service identifier, the first terminal clears the DNS cache associated with the service identifier.

[0170] In some embodiments of the present application, before the first network element transmits a second data network access identifier of a first terminal to the second network element, or transmits first instruction information to the first terminal, the communication method further includes the first network element determining a second data network access identifier when the first network element determines that the first terminal has been disassociated from the first terminal set.

[0171] For example, the first network element is an SMF network element. The SMF network element may obtain a second data network access identifier from network elements such as an AMF network element and an LMF network element, or it may determine the second data network access identifier locally, or the SMF network element may determine the second data network access identifier of the first terminal based on the UPF network element and the DN network elements connected to the UPF network element by determining the UPF network element. This is not limited to the present invention.

[0172] In some embodiments of the present application, when a first network element determines a second data network access identifier, the communication method further includes the first network element determining that a first edge application server is not suitable to provide services to a first terminal.

[0173] One reason why the first edge application server might be unsuitable for servicing the first terminal could be that the first terminal is far from the first edge application server. For example, the first terminal moves, and is then far from the first edge application server. In this case, the distance between the first terminal and the first edge application server is no longer optimal. This affects the first edge application server's ability to serve the first terminal. Alternatively, the first terminal might no longer require the first edge application server to provide services. For example, in room 1 of game A, the user corresponding to the first terminal leaves the game, the first terminal leaves room 1, and no longer needs to access the first edge application server. The reasons why the first edge application server might be unsuitable for servicing the first terminal are not limited herein.

[0174] In one example, a first network element may determine whether a first edge application server is suitable to serve the first terminal based on the first terminal's second data network access identifier. If the first edge application server is suitable to serve the first terminal, the first network element does not need to send the second data network access identifier to the second network element. If the first edge application server is not suitable to serve the first terminal, the first network element sends the second data network access identifier to the second network element.

[0175] For example, the first network element is an SMF network element. If the second data network access identifier is the same as the common DNAI accessed by the first set of terminals, or if the second data network access identifier is the same as the DNAI corresponding to the common EAS, the SMF network element determines that the common EAS or the EAS corresponding to the common DNAI is suitable for servicing the first terminal. If the second data network access identifier is different from the common DNAI, or if the second data network access identifier is different from the DNAI corresponding to the common EAS, the SMF network element determines that the common EAS or the EAS corresponding to the common DNAI is not suitable for servicing the first terminal.

[0176] In some embodiments of the present application, before the first network element determines that the first terminal has been disassociated from the first terminal set, the communication method further includes the first network element receiving second instruction information, the second instruction information indicating that the first terminal has been disassociated from the first terminal set.

[0177] For example, the first network element is an SMF network element. The second instruction information may be transmitted to the SMF network element via a PCF network element, and the SMF network element determines, based on the second instruction information, that the first terminal has been disassociated from the first terminal set.

[0178] In some embodiments of the present application, before the first network element determines that the first terminal has been disassociated from the first terminal set, the communication method further includes the following steps:

[0179] Step a: A first network element receives a first message. The first message includes an identifier for a first set of terminals and third directive information. The third directive information indicates that each terminal in the first set of terminals needs to access a common EAS or common DNAI. The first message may further include a first edge application server or a first data network access identifier.

[0180] In one example, the first message is a PCC rule, which includes a correlation identifier (an identifier for the first set of terminals) and common EAS or common DNAI (third-party reference information).

[0181] Step b: The first terminal accesses the first edge application server.

[0182] Specifically, the process described in the above embodiments, in which multiple terminals within the first terminal set access the common EAS or common DNAI, is again not described herein.

[0183] It should be noted that the first terminal is not necessarily the terminal that initiates the DNS query first in the first terminal set. The common EAS or common DNAI corresponding to the first terminal set is not necessarily selected via the first terminal's PDU session, and it should be understood that the common EAS or common DNAI for the first terminal set is not necessarily determined based on or by considering the first terminal. Therefore, the EAS corresponding to the common EAS or common DNAI is not necessarily the most suitable EAS for servicing the first terminal.

[0184] Step c: The first network element receives the second message. The second message does not contain the identifier of the first terminal set and / or the third directive information, or the second message contains the second directive information, which indicates that the first terminal has been disassociated from the first terminal set.

[0185] For example, the second message is an updated PCC rule and does not contain a correlation identifier and / or common EAS or common DNAI instruction information. When the updated PCC rule is compared with the PCC rule in step a, the first terminal may determine that it no longer requires an EAS corresponding to a common EAS or common DNAI to provide the service.

[0186] For example, the second message is an updated PCC rule. The updated PCC rule includes a correlation identifier and second instruction information.

[0187] In this way, the first network element can determine, based on the first message and the second message, that the first terminal has been disassociated from the first terminal set.

[0188] The third identifier may be a service identifier, such as a service data flow (SDF), an application identifier (App ID), or a fully qualified domain name (FQDN).

[0189] It should be noted that in some scenarios, PCC rules or updated PCC rules do not need to be limited by service identifiers. For example, regardless of the service accessed, the first terminal either belongs to the first terminal set or has a requirement to access the common EAS or common DNAI. In this case, the PCC rules or updated PCC rules do not need to be limited by service identifiers. In most scenarios other than the one described above, some services of the first terminal require the common EAS or common DNAI, while some services do not, and different services require different common EAS or common DNAIs. Therefore, service identifiers are necessary to limit PCC rules or updated PCC rules.

[0190] In some embodiments of the present application, the method provided in this embodiment of the application further includes the first network element deciding to transmit the second data network access identifier of the first terminal to the second network element before the first network element transmits the second data network access identifier of the first terminal to the second network element.

[0191] If the second network element determines that an EAS corresponding to a common EAS or common DNAI is suitable for servicing the first terminal, for example, if the second edge application server selected based on the second data network access identifier is the same as the EAS corresponding to the first DNAI or the first EAS, the second network element will no longer perform the edge application server migration.

[0192] In some embodiments of the present application, the first network element further transmits fourth instruction information to the second network element. The fourth instruction information is used to request the second network element to select a second edge application server for the first terminal. In response, the second network element receives the fourth instruction information from the first network element.

[0193] For example, the first network element is an SMF network element, and the second network element is an AF network element. The SMF network element transmits information to the AF network element requesting the selection of an EAS, and the AF network element selects an EAS suitable for providing services for the first terminal based on the second data network access identifier and the information requesting the selection of an EAS. The fourth instruction information may be in any other form used to request the selection of an EAS, and is not limited herein.

[0194] In some embodiments of the present application, after a second network element selects a second edge application server based on a second data network access identifier, or based on the second data network access identifier and fourth instruction information, the method provided in this embodiment of the present application further includes the second network element transmitting edge application server address substitution information to the first network element. The first network element receives the edge application server address substitution information. The edge application server address substitution information is used by the first terminal to connect to the second edge application server.

[0195] The edge application server address substitution information includes the IP address and port number of the first edge application server and the IP address and port number of the second edge application server.

[0196] In the embodiment described above, the first network element is a session management network element, and the second network element is an application network element.

[0197] For example, other communication methods provided in embodiments of the present application may be performed by a functional module in a second network element, which can be operated by calling a program, or by a communication device used in the second network element, such as a chip, chip system, or integrated circuit. The chip, chip system, or integrated circuit may be located within the second network element or independently of the second network element. This is not limited to embodiments of the present application.

[0198] Figure 5 shows another communication method according to one embodiment of the present invention. This method includes the following steps.

[0199] Step 501: The second network element determines that the first terminal has been disassociated from the first terminal set. The first terminal set includes multiple terminals, which access the first edge application server or the first data network access identifier.

[0200] Optionally, after step 501, the second network element may perform either step 502a or step 502b below.

[0201] Step 502a: The second network element determines the second edge application server that corresponds to the first terminal.

[0202] Step 502b: The second network element sends edge application server rediscovery-related instruction information to the first network element, or sends edge application server relocation-related information to the first network element.

[0203] Edge application server relocation-related information is used by the first network element to decide whether to rediscover or relocate the edge application server, or to instruct the first network element to trigger an edge application server relocation.

[0204] If, optionally, a second network element performs step 502b, the method provided in this embodiment of the Application may further include the following steps:

[0205] Step 503: The first network element sends edge application server rediscovery-related instruction information to the first terminal, or sends edge application server relocation-related information to the first terminal. In response, the first terminal receives either the edge application server rediscovery-related instruction information or the edge application server relocation-related information.

[0206] Step 504: The first terminal performs either edge application server address substitution or edge application server rediscovery.

[0207] In the embodiments described above, after the second network element determines that the first terminal has been disassociated from the first terminal set, the second network element may determine a second edge application server corresponding to the first terminal, or it may send edge application server rediscovery instruction information or edge application server relocation information to the first network element, and the first network element may trigger the first terminal to select an appropriate edge application server in order to select a better edge application server for the first terminal, thereby reducing the latency of the first terminal and improving the user experience.

[0208] In some embodiments of the present application, the method provided in this embodiment may further include the second network element determining a second data network access identifier for the first terminal before the second network element decides to determine a second edge application server corresponding to the first terminal or to transmit edge application server relocation information to the first network element.

[0209] For example, a second network element may obtain the second data network access identifier of the first terminal by subscribing to the terminal's data network access identifier change event.

[0210] In one example, the first network element is an SMF network element, and the second network element is an AF network element. The AF network element may send a subscription message to the SMF network element. The subscription message is used to subscribe to a second data network access identifier provided by the SMF network element for the AF network element when any terminal in the terminal set or a designated terminal (e.g., the first terminal) leaves the terminal set.

[0211] In some embodiments of the present application, a method for a second network element to determine a second data network access identifier for a first terminal includes the second network element requesting the second data network access identifier for the first terminal from the first network element. The second network element receives the second data network access identifier from the first network element.

[0212] For example, a second network element transmits a fifth instruction to a first network element. The fifth instruction is used to request a second data network access identifier for the first terminal. The second network element may request the second data network access identifier for the first terminal in other ways, but is not limited herein.

[0213] In some embodiments of the present application, after a second network element determines a second edge application server corresponding to a first terminal, the method provided in this embodiment further includes the second network element transmitting edge application server address substitution information to the first network element. In response, the first network element receives the edge application server address substitution information from the second network element. For example, the edge application server address substitution information is used by the first terminal to connect to the second edge application server.

[0214] For information regarding the edge application server address substitution, please refer to the embodiments described above. Further details will not be provided again in this specification.

[0215] Optionally, after the first network element receives edge application server address substitution information from the second network element, the method provided in this embodiment of the Application may further include the first network element performing EAS address substitution. For the process of performing EAS address substitution by the first network element, please refer to the description in the above embodiments. Further details are not described herein.

[0216] The following describes the process by which the SMF network element triggers the AF network element to re-select the EAS for the first terminal after the first terminal has left the first terminal set, using an example where the first network element is an SMF network element and the second network element is an AF network element. A schematic flowchart of a communication method according to one embodiment of the present invention is described with reference to Figure 6. This method includes the following steps.

[0217] Step 601: The AF network element sends a first message to the PCF network element. In response, the PCF network element receives a first message from the AF network element.

[0218] For example, the first message includes a member list of the first terminal set, a traffic correlation identifier, and common EAS or common DNAI instruction information.

[0219] For example, a traffic correlation identifier identifies a first set of terminals.

[0220] Optionally, the first message may further include a service identifier. The service identifier is from the common EAS or common DNAI and indicates a service that needs to be accessed by each terminal in the first set of terminals.

[0221] For example, the member list of the first set of terminals includes the identification information of the first terminal and the identification information of one or more terminals other than the first terminal.

[0222] For example, common EAS directives are used to determine that each terminal in the first set of terminals needs to access the common EAS. For example, the common EAS is the aforementioned first edge application server.

[0223] For example, the common DNAI directive indicates that each terminal in the first set of terminals needs to access the common DNAI. For example, the common EAS is the first data network access identifier.

[0224] Specifically, the AF network element transmits to the UDR network element a member list of the first terminal set, traffic correlation identifiers, and common EAS or common DNAI instruction information. The UDR network element transmits to the PCF network element a member list of the first terminal set, traffic correlation identifiers, and common EAS or common DNAI instruction information. The PCF network element generates a PCC rule based on the member list of the first terminal set, traffic correlation identifiers, and common EAS or common DNAI instruction information. For example, a PCC rule includes a member list of the first terminal set, traffic correlation identifiers, and common EAS or common DNAI instruction information. Optionally, a PCC rule may further include a service identifier.

[0225] Step 602: The PCF network element sends a second message to the SMF network element. In response, the SMF network element receives a second message from the PCF network element.

[0226] For example, the second message includes a traffic correlation identifier and common EAS or common DNAI instruction information.

[0227] Optionally, a PCF network element may further transmit a service identifier to an SMF network element to determine the specific service accessed by each terminal in the first set of terminals.

[0228] For example, a third message sent by a PCF network element to an SMF network element contains a PCC rule. Alternatively, the third message is a PCC rule.

[0229] For example, information may be transmitted through an AF traffic influence procedure. However, provided that an SMF network element obtains the information, the process and manner in which the SMF network element obtains the information are not limited to these embodiments of the Application, and the SMF network element does not necessarily have to obtain the information by using PCC rules.

[0230] Step 603: The SMF network element performs either the common EAS selection procedure or the common DNAI selection procedure.

[0231] It should be noted that in the process by which an SMF network element selects a common EAS or common DNAI, the first terminal is not necessarily the terminal that initiates the DNS query within the first terminal set. The common EAS or common DNAI corresponding to the first terminal set is not necessarily selected via the first terminal's PDU session, and the common EAS or common DNAI for the first terminal set is not necessarily determined based on or taking the first terminal into consideration. Therefore, the EAS corresponding to the common EAS or common DNAI is not necessarily the most suitable EAS for servicing the first terminal.

[0232] Step 604: The AF network element determines that the first terminal has been disassociated from the first terminal set.

[0233] For example, when the first terminal moves, the distance between the first terminal and the common EAS increases, or the common EAS currently accessed by the first terminal becomes overloaded. Therefore, the common EAS is no longer suitable for providing services for the first terminal. The first terminal no longer needs to access the common EAS or common DNAI with other terminals in the first terminal set.

[0234] The first terminal may be any terminal in the first terminal set, and the first terminal may actively leave the first terminal set, for example, if the distance between the first terminal and the common EAS becomes longer. Alternatively, the first terminal may not need to continue accessing services on the common EAS, or the first terminal may be a terminal selected from the first terminal set by an AF network element.

[0235] Step 605: The AF network element sends a third message to the PCF network element. In response, the PCF network element receives a third message from the AF network element.

[0236] For example, the third message includes the updated member list of the first terminal set, a traffic correlation identifier, and common EAS or common DNAI instruction information.

[0237] The updated member list of the first terminal set does not include the identification information of the first terminal.

[0238] In one example, the AF network element first sends a third message to the UDR network element, which includes the updated member list of the first terminal set, the traffic correlation identifier, and the common EAS instruction information or common DNAI instruction information. The UDR network element then sends the updated member list of the first terminal set, the traffic correlation identifier, and the common EAS instruction information or common DNAI instruction information to the PCF network element.

[0239] Alternatively, step 605 may be replaced with the following: The AF network element sends a third message to the UDR network element, and the UDR network element sends a third message to the PCF network element.

[0240] Optionally, an AF network element sending a third message to a UDR network element may further include sending a traffic correlation identifier. The UDR network element then sends the traffic correlation identifier to a PCF network element.

[0241] Step 606: The PCF network element sends a fourth message to the SMF network element. In response, the SMF network element receives a fourth message from the PCF network element.

[0242] For example, the fourth message does not contain a traffic correlation identifier and / or common EAS or common DNAI directive information.

[0243] For example, the fourth message does not contain a traffic correlation identifier and / or common EAS or common DNAI directive information.

[0244] For example, the fourth message includes a traffic correlation identifier and second instruction information.

[0245] In one example, the fourth message includes an updated PCC rule, and the updated PCC rule does not include a traffic correlation identifier and / or common EAS or common DNAI instruction information.

[0246] In another example, a PCF network element sends an updated PCC rule to an SMF network element, and the updated PCC rule includes a traffic correlation identifier and second instruction information.

[0247] Note that the transmission of updated PCC rules from PCF network elements to SMF network elements occurs at the PDU session granularity, and the updated PCC rules do not need to include the identification information of the first terminal.

[0248] It can be understood that steps 601 to 606 merely indicate that the information may be transmitted to the SMF network element as updated PCC rules, or otherwise transmitted to the SMF network element by carrier, and is not limited to this.

[0249] Step 607: The SMF network element determines that the first terminal has been disassociated from the first terminal set.

[0250] For example, the fourth message sent by the PCF network element to the SMF network element in steps 602 and 606 is at the PDU session granularity, and since one PDU session can serve only one terminal, the scope of the PCC rule is naturally the current PDU session, and it can be determined that the terminal is the first terminal. Therefore, the SMF network element receives the updated PCC rule because the updated PCC rule does not contain the traffic correlation identifier and / or common EAS or common DNAI directive information. The SMF network element can determine that the first terminal has been disassociated from the first terminal set by comparing the updated PCC rule with the received PCC rule which contains the traffic correlation identifier and common EAS or common DNAI directive information.

[0251] For example, an SMF network element receives a fourth message, which contains second instruction information indicating that the first terminal has been disassociated from the first terminal set. Therefore, the SMF network element determines that the first terminal has been disassociated from the first terminal set.

[0252] For example, an SMF network element compares the updated member list of the first terminal set with the previously retrieved member list of the first terminal set. If the updated member list of the first terminal set lacks the identification information of the first terminal compared to the member list of the first terminal set, the SMF network element determines that the first terminal has been disassociated from the first terminal set.

[0253] Step 608: The SMF network element determines the second data network access identifier for the first terminal based on the fact that the first terminal has been disassociated from the first terminal set.

[0254] For example, an SMF network element may obtain a second data network access identifier from network elements such as an AMF network element and an LMF network element, or the SMF network element may autonomously determine the second data network access identifier.

[0255] Optionally, when the first terminal is disassociated from the first terminal set, the SMF network element corresponds to the common EAS or common DNAI accessed by the first terminal and determines whether the EAS accessed by the first terminal is suitable for servicing the first terminal.

[0256] For example, if the second data network access identifier is the same as the common DNAI accessed by the first set of terminals, or if the second data network access identifier is the same as the DNAI corresponding to the common EAS, the SMF network element determines that the common EAS or the EAS corresponding to the common DNAI is suitable for servicing the first terminal. If the second data network access identifier is different from the common DNAI, or if the second data network access identifier is different from the DNAI corresponding to the common EAS, the SMF network element determines that the common EAS or the EAS corresponding to the common DNAI is not suitable for servicing the first terminal.

[0257] Step 609: The SMF network element decides to send the second data network access identifier of the first terminal to the AF network element.

[0258] For example, an SMF network element decides to send a second data network access identifier to an AF network element based on the fact that a first terminal has left the first terminal set.

[0259] For example, if in step 608 it is determined that the common EAS is not suitable to provide services to the first terminal, the SMF network element decides that the first terminal leaves the first terminal set and transmits a second data network access identifier to the AF network element based on the fact that the common EAS is not suitable to provide services to the first terminal.

[0260] Step 610: The SMF network element transmits the second data network access identifier of the first terminal to the AF network element. In response, the AF network element receives the second data network access identifier from the SMF network element.

[0261] Optionally, the SMF network element sends a third instruction to the AF network element to request the AF network element to select a second edge application server for the first terminal.

[0262] It can be understood that an AF network element may send a subscription message to an SMF network element. The subscription message is used to subscribe to a second data network access identifier provided by the SMF network element for the AF network element when any terminal in the terminal set or a designated terminal (e.g., the first terminal) leaves the terminal set. In this way, when any terminal or a designated terminal (e.g., the first terminal) decides to leave the terminal set, the SMF network element performs step 610.

[0263] Step 611: The AF network element selects a second edge application server based on the second data network access identifier of the first terminal.

[0264] When the AF network element receives further third instruction information from the SMF network element, if the AF network element determines that the common EAS is not suitable to service the first terminal, the AF network element selects a second edge application server for the first terminal based on a second data network access identifier.

[0265] Optionally, when a second edge application server selected for a terminal based on the second data network access identifier of the first terminal by an AF network element is different from the first edge application server, the method provided in this embodiment of the Application may further include steps 612 and 613.

[0266] If the second edge application server selected for the terminal based on the second data network access identifier of the first terminal by the AF network element is the same as the first edge application server, steps 612 and 613 may be omitted.

[0267] Step 612: The AF network element sends edge application server address substitution information to the SMF network element. In response, the SMF network element receives edge application server address substitution information from the AF network element.

[0268] The edge application server address substitution information includes the IP address and port number of the EAS corresponding to the common EAS or common DNAI, as well as the IP address and port number of the second edge application server. After receiving the edge application server address substitution information, the SMF network element configures the L-PSA. In one example, the SMF configures the contents of the L-PSA. Specifically, the SMF may instruct the L-PSA to modify the destination address of uplink packets whose destination address is the address of the first EAS to the address of the second EAS, and to modify the source address of downlink packets whose source address is the address of the second EAS to the address of the first EAS.

[0269] Specifically, after selecting a second edge application server based on a second data network access identifier, the AF network element copies the context of the first terminal running on an EAS corresponding to common EAS or common DNAI to the second edge application server, including the user's application information (e.g., role status in an ongoing game and progress of a video being watched).

[0270] Step 613: The SMF network element performs edge application server address substitution.

[0271] For example, the edge application server address substitution information includes the IP address and port number of the first edge application server and the IP address and port number of the second edge application server.

[0272] In some embodiments of the present application, if a first terminal needs to change terminal sets, for example, if the first terminal needs to be moved from the first terminal set to a second terminal set, the first network element receives information about the second terminal set. Before the first network element determines that the first terminal has been disassociated from the first terminal set, the second message received by the first network element further includes an identifier for the second terminal set, and multiple terminals in the second terminal set need to access a third edge application server or a third data network access identifier.

[0273] The following schematic flowchart of another communication method according to one embodiment of the present invention will be described with reference to Figure 7, using an example in which the first network element is an SMF network element and the second network element is an AF network element. The difference between this method and the method in the embodiment shown in Figure 6 is as follows: In the embodiment shown in Figure 7, when the first terminal leaves the terminal set, the SMF network element transmits the DNAI of the first terminal to the AF. In the embodiment shown in Figure 7, when the first terminal leaves the terminal set, the SMF network element triggers EAS rediscovery for the first terminal. This method includes the following steps.

[0274] Steps 701 to 705a are the same as steps 601 to 605 described in the above embodiments. Further details are not described herein.

[0275] Step 705b is performed if the first terminal needs to change terminal sets, for example, if the first terminal needs to be moved from the first terminal set to the second terminal set.

[0276] Step 705b: The AF network element sends a fifth message to the PCF network element. In response, the PCF network element receives a fifth message from the AF network element.

[0277] For example, the fifth message includes a member list of the first terminal set (including identification information for one or more terminals and identification information for the first terminal), a second traffic correlation identifier (identification information for the second terminal set), and common EAS instruction information or common DNAI instruction information.

[0278] Step 706 is the same as step 606. Further details are again not described herein.

[0279] In one example, a PCF network element sends an updated PCC rule to an SMF network element, and the updated PCC rule includes a second traffic correlation identifier.

[0280] Step 707: The SMF determines that either the first terminal has been disassociated from the first terminal set, or the first terminal has joined the second terminal set.

[0281] For the implementation of step 707, please refer to the description in the embodiments above. Further details are not provided herein.

[0282] In one example, an SMF network element determines that a first terminal joins a second set of terminals based on a second correlation identifier.

[0283] Step 708: The SMF network element determines the second data network access identifier for the first terminal based on whether the first terminal has been disassociated from the first terminal set or whether the first terminal has joined the second terminal set.

[0284] Optionally, the SMF network element corresponds to a common EAS or common DNAI accessed by the first terminal and determines whether the EAS accessed by the first terminal is suitable for providing services to the first terminal.

[0285] For example, in one implementation, when determining the second data network access identifier of the first terminal, the SMF network element corresponds to the common EAS or common DNAI accessed by the first terminal, and may not perform an action to determine whether the EAS accessed by the first terminal is suitable for providing services to the first terminal. This is because regardless of whether the EAS corresponding to the common EAS or common DNAI is suitable for providing services to the first terminal, the SMF network element may need to send the second data network access identifier of the first terminal to the AF network element.

[0286] For example, in another implementation, when determining the second data network access identifier for the first terminal, if the SMF network element corresponds to the common EAS or common DNAI accessed by the first terminal and does not perform an action to determine whether the EAS accessed by the first terminal is suitable for providing services to the first terminal, the SMF network element does not need to obtain the second data network access identifier of the first terminal. Therefore, step 708 may be omitted.

[0287] Step 709: The SMF network element determines to send the first indication information to the first terminal.

[0288] In one example, the SMF network element determines to send the first indication information to the first terminal only based on the fact that the first terminal has been disassociate from the first terminal set or the first terminal is participating in the second terminal set.

[0289] In another example, when it is determined in step 708 whether the EAS accessed by the first terminal and corresponding to the common EAS or common DNAI is suitable for the first terminal to provide services, if the first terminal is disassembled from the first terminal set or the first terminal joins the second terminal set and the EAS corresponding to the common EAS or common DNAI is not suitable for the first terminal to provide services, the SMF may determine to send the first indication information to the first terminal.

[0290] Step 710: The SMF network element sends the first indication information to the first terminal. Correspondingly, the first terminal receives the first indication information from the SMF network element.

[0291] For example, the SMF network element may send a PDU session update message to the first terminal. Correspondingly, the first terminal receives the PDU session update message from the SMF network element. The PDU session update message includes the first indication information. For example, the first indication information is EAS rediscovery indication information.

[0292] The PDU session update message is a PDU session change command.

[0293] Optionally, the PDU session update message further includes a service identifier.

[0294] Step 711: The first terminal clears the corresponding DNS cache information.

[0295] For example, if the first indication information further indicates to the first terminal to clear the DNS cache information, the first terminal clears the corresponding DNS cache information based on the first indication information.

[0296] For example, if, in addition to sending first instruction information to the first terminal, the SMF network element may further send instruction information to the first terminal to instruct it to clear its DNS cache, the first terminal may clear the corresponding DNS cache information based on the instruction information to clear its DNS cache.

[0297] For example, after receiving the first instruction information, if the SMF network element determines that the EAS needs to be re-selected, the first terminal deletes the DNS cache information.

[0298] Optionally, the first instruction information includes a service identifier, and the first terminal clears the DNS cache associated with the service identifier.

[0299] The following describes the process by which the AF network element re-selects an EAS for a first terminal after the first terminal leaves the first terminal set, using an example where the first network element is an SMF network element and the second network element is an AF network element. Referring to Figure 8, a schematic flowchart of further other communication methods according to one embodiment of the present application is described. The difference between this method and the methods in the embodiments shown in Figures 6 and 7 is as follows: In the embodiments shown in Figures 6 and 7, the SMF network element triggers the AF network element to re-select an EAS for the first terminal, or the SMF network element triggers edge application server rediscovery for the first terminal. In the embodiment shown in Figure 8, the AF network element directly selects a second edge application server for the first terminal. This method includes the following steps.

[0300] Steps 801 to 804 are the same as steps 601 to 604 or steps 701 to 704 described in the above embodiments. Further details are again not described herein.

[0301] Step 805: When it is determined that the first terminal has been disassociated from the first terminal set, the AF network element determines the second data network access identifier for the first terminal.

[0302] For example, an AF network element subscribes to a terminal's data network access identifier change event. When any terminal in the first terminal set leaves the first terminal set, the SMF network element autonomously provides a second data network access identifier for the AF network element.

[0303] Note that if an AF network element has previously subscribed to the terminal's data network access identifier change event and has already received the data network access identifier sent by the SMF network element, then the AF network element has already obtained and determined the second data network access identifier for the first terminal, or the SMF network element has already obtained the second data network access identifier for the first terminal by other means. In this case, step 806 may not be performed. Alternatively, if the AF network element does not obtain and determine the second data network access identifier for the first terminal, then step 806 must be performed.

[0304] Step 806: The AF network element sends a sixth message to the SMF network element. In response, the SMF network element receives a sixth message from the AF network element.

[0305] For example, the sixth message is used by an SMF network element to decide whether to provide the AF network element with a second data network access identifier for the first terminal. For example, the sixth message may include fifth directive information, which is used to request the second data network access identifier for the first terminal. Alternatively, the directive information contained in the sixth message indicates that the first terminal has been disassociated from the first terminal set.

[0306] Optionally, the AF network element further transmits a service identifier to the SMF network element. For example, the sixth message may include a service identifier.

[0307] Specifically, the AF network element sends a sixth message (optionally, a service identifier) ​​to the UDR network element. The UDR network element sends a sixth message (optionally, a service identifier) ​​to the PCF network element. The PCF network element sends a sixth message (optionally, a service identifier) ​​to the SMF network element.

[0308] An AF network element may transmit a sixth message to an SMF network element in multiple ways. For example, the AF network element may transmit through an AF traffic impact procedure. In this way, since the updated PCC rule between the PCF network element and the SMF network element is at the PDU session granularity, only the portion transmitted by the AF network element to the UDR network element or the PCF network element needs to include the identification information of the first terminal, and the identification information of the first terminal does not need to be transmitted to the SMF network element. Alternatively, the AF network element may transmit to the SMF network element through a non-PDU session (for example, at terminal granularity). In this way, the transmission granularity may include multiple terminals. In this case, the identification information of the first terminal needs to be transmitted. The methods by which the AF network element transmits a fifth message to an SMF network element are not limited in this application.

[0309] Step 807: The SMF network element sends the second data network access identifier of the first terminal to the AF network element. Correspondingly, the AF network element receives the second data network access identifier from the SMF network element.

[0310] For example, the AF network element subscribes to a data network access identifier change event of the terminal. When any terminal in the first terminal set exits the first terminal set, the SMF network element sends the second data network access identifier to the AF network element.

[0311] For example, the SMF network element sends the second data network access identifier of the first terminal to the AF network element based on the fifth instruction information sent by the AF network element.

[0312] Step 808: The AF network element determines a second edge application server for the first terminal based on the second data network access identifier.

[0313] For example, in a possible implementation, the AF network element determines that the first terminal has exited the first terminal set and determines to select a second edge application server for the first terminal. In other words, the AF network element triggers EAS reselection on condition that the AF network element determines that the first terminal has exited the first terminal set.

[0314] In another possible implementation, when the first terminal exits the first terminal set and the common EAS is not suitable for providing services to the first terminal, the AF network element may determine to select a second edge application server for the first terminal.

[0315] In another example, an AF network element might decide to select a second edge application server corresponding to a first terminal based on the fact that the first terminal has been disassociated from the first terminal set and that the common EAS is not suitable for servicing the first terminal. It can be understood that the selection of the second edge application server is triggered only when both conditions are met.

[0316] In the example described above, the AF network element may also determine the second edge application server based on the second data network access identifier.

[0317] Steps 809 and 810 are the same as steps 612 and 613 in the embodiments described above. Further details are again not described herein.

[0318] The following describes the process by which the AF network element re-selects an EAS for a first terminal after the first terminal leaves the first terminal set, using an example where the first network element is an SMF network element and the second network element is an AF network element. Referring to Figure 9, a schematic flowchart of another communication method according to one embodiment of the present application is described. The difference between this method and the method in the embodiment shown in Figure 8 is as follows: In the embodiment shown in Figure 8, when the first terminal leaves the terminal set, the AF network element determines the second edge application server for the first terminal. In the embodiment shown in Figure 9, when the first terminal leaves the terminal set, the SMF network element transmits edge application server rediscovery instruction information or edge application server relocation related information to the SMF network element. This method includes the following steps.

[0319] Steps 901 to 907 are the same as steps 801 to 807 described in the above embodiments. Further details are not described herein.

[0320] Step 908: The AF network element decides to send edge application server relocation information to the first terminal based on the fact that the first terminal has been disassociated from the first terminal set.

[0321] Optionally, the AF network element further determines, based on the second data network access identifier of the first terminal, whether an EAS corresponding to a common EAS or common DNAI is suitable for servicing the first terminal.

[0322] For example, the second data network access identifier is compared to the common DNAI accessed by the first set of terminals. A specific implementation is shown in step 608. Further details are not described herein.

[0323] Step 909: The AF network element sends edge application server relocation-related information to the SMF network element. In response, the SMF network element receives edge application server relocation-related information from the AF network element.

[0324] For example, edge application server relocation-related information includes EAS relocation instruction information.

[0325] Optionally, edge application server relocation-related information may further include service identifiers.

[0326] Specifically, the AF network element first sends edge application server relocation information to the UDR network element, the UDR network element then sends edge application server relocation information to the PCF network element, and finally, the PCF network element sends edge application server relocation information to the SMF network element.

[0327] Steps 910 and 911 are the same as steps 710 and 711 in the embodiments described above. Further details are again not described herein.

[0328] The above primarily describes the solutions in the embodiments of the present application from the perspective of the interactions between network elements. To implement the aforementioned functions, it can be understood that network elements, such as the first and second network elements, include corresponding structures and / or software modules for implementing the functions. Those skilled in the art will readily recognize, in combination with the example units and algorithmic steps described in the embodiments disclosed herein, that the present application can be implemented in hardware or in combination of hardware and computer software. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementations should not be considered to be beyond the scope of the present application.

[0329] In embodiments of the present application, the first and second network elements may each be divided into functional units based on the examples of the methods described above. For example, each functional unit may be obtained through a division based on a corresponding function, or two or more functions may be integrated into a single processing unit. The integrated unit may be implemented in hardware form or in the form of a software functional unit. Note that in embodiments of the present application, the division into units is merely an example and represents only a logical functional division. Other division methods may be used in actual implementation.

[0330] The above describes the method in the embodiments of the present application with reference to Figures 4 and 5. Below, a communication device provided in the embodiments of the present application that performs the method described above will be described. Those skilled in the art will understand that the method and the device can be combined and referenced together. The communication device provided in the embodiments of the present application can perform the steps performed by the first and second network elements in the communication method shown in Figures 4 and 5.

[0331] When an integrated unit is used, Figure 10 shows the communication device in the embodiment described above. The communication device may include a communication module 1002 and a processing module 1001.

[0332] In an optional implementation, the communication device may further include a storage module 1003 configured to store the program code and data of the communication device.

[0333] In one example, the communication device is either the first network element 201 or a chip used in the first network element 201. In this case, the processing module 1001 is configured to support the communication device when performing step 401 in the above embodiment. The communication module 1002 is configured to support the communication device when performing the transmission action performed by the first network element 201 in step 402 in the above embodiment.

[0334] In other examples, the communication device is either a second network element 202 or a chip used in the second network element 202. In this case, the processing module 1001 is configured to support the communication device when performing steps 501, 502a, and 502b in the above-described embodiment. The communication module 1002 is configured to support the communication device when performing a transmission action performed by the second network element in step 502a or step 502b in the above-described embodiment.

[0335] The processing module 1001 may be a processor or a controller, for example, a central processing unit, a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processing module may implement or run various exemplary logic blocks, modules, and circuits described with reference to what is disclosed herein. Alternatively, the processor may be a combination of processors that implement computing functions, for example, a combination of one or more microprocessors, or a combination of a digital signal processor and a microprocessor. The communication module may be a transceiver, a transceiver circuit, a communication interface, etc. The storage module may be memory.

[0336] When the processing module 1001 is a processor 1101 or a processor 1105, the communication module 1002 is a communication interface 1103, and the storage module 1003 is a memory 1102, the communication device in this application may be the communication device shown in Figure 11.

[0337] Figure 11 is a diagram of the hardware structure of a communication device according to an embodiment of the present invention. It includes a processor 1101, a communication line 1104, and at least one communication interface (in Figure 11, communication interface 1103 is used as an example for illustrative purposes).

[0338] The processor 1101 may be a central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to control the execution of a program in the solution of this application.

[0339] The communication line 1104 may include a path for transmitting information between the above-mentioned components.

[0340] The communication interface 1103 is configured to exchange information with other devices via any type of device, such as a transceiver, and to communicate with other devices or communication networks, such as Ethernet®, a radio access network (RAN), or a wireless local area network (WLAN).

[0341] Optionally, the communication device may further include memory 1102.

[0342] Memory 1102 may be a read-only memory (ROM), or another type of static storage device capable of storing static information and instructions; or a random access memory (RAM), or another type of dynamic storage device capable of storing information and instructions. Alternatively, memory 1102 may be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM), or another compact disc storage device; an optical disc storage device (including compact optical discs, laser discs, optical discs, digital multipurpose discs, Blu-ray discs, etc.); a magnetic disc storage medium, or another magnetic storage device; or any other medium that may be configured to carry or store expected program code in the form of instructions or data structures and that can be accessed by a computer. However, memory 1102 is not limited to these. Memory may exist independently and be connected to the processor via a communication line 1104. Memory may also be integrated with the processor.

[0343] Memory 1102 is configured to store computer executable instructions used to implement the solution in the present application, and execution is controlled by processor 1101. Processor 1101 is configured to execute computer executable instructions stored in memory 1102 to implement the communication method provided in the aforementioned embodiments of the present application.

[0344] Optionally, the computer executable instructions in this embodiment of the application may also be referred to as application code. This is not particularly limited to this embodiment of the application.

[0345] In a specific implementation, in one embodiment, the processor 1101 may include one or more CPUs, for example, CPU0 and CPU1 in Figure 11.

[0346] In a specific implementation, in one embodiment, the communication device may include a plurality of processors, for example, processors 1101 and 1105 in Figure 11. Each of the processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor as used herein may be one or more devices, circuits, and / or processing cores configured to process data (e.g., computer program instructions).

[0347] For steps performed by processors 1101 and 1105, please refer to the steps performed by processing module 1001. For steps performed by communication interface 1103, please refer to the steps performed by communication module 1002.

[0348] Figure 12 shows the structure of a chip 120 according to one embodiment of the present invention. The chip 120 includes one or more (including two) processors 1210 and a communication interface 1230.

[0349] Optionally, the chip 120 further includes memory 1240, which includes read-only memory and random access memory and can provide operational instructions and data to the processor 1210. A portion of memory 1240 may further include non-volatile random access memory (NVRAM).

[0350] In some embodiments, memory 1240 stores the following elements, executable modules or data structures, subsets thereof, or extensions thereof:

[0351] In this embodiment of the present invention, the corresponding operation is performed by calling an operation instruction stored in memory 1240 (the operation instruction may be stored in the operating system).

[0352] The processor 1210 controls the processing operation of one of the first network element, the second network element, and the first terminal. The processor 1210 may also be referred to as a central processing unit (CPU).

[0353] Memory 1240 includes read-only memory and random-access memory, and can provide instructions and data to processor 1210. A portion of memory 1240 may further include NVRAM. For example, during application, memory 1240, communication interface 1230, and memory 1240 are coupled to each other via bus system 1220. In addition to the data bus, bus system 1220 may further include a power bus, control bus, status signal bus, etc. However, for clarity, various buses are shown as bus system 1220 in Figure 12.

[0354] The methods disclosed in the aforementioned embodiments of the present application may be applied to or implemented by a processor 1210. The processor 1210 may be an integrated circuit chip having signal processing capabilities. In the implementation process, the steps of the aforementioned methods may be implemented through hardware integrated logic circuits or software instructions within the processor 1210. The processor 1210 may be a general-purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA), or other programmable logic device, discrete gate, transistor logic device, or discrete hardware component. The processor may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. The steps in the methods disclosed with reference to embodiments of the present application may be performed and completed directly by a hardware decoding processor, or by using a combination of hardware and software modules within the decoding processor. The software module may be placed in a mature storage medium in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. The storage medium is placed in memory 1240. The processor 1210 reads the information in memory 1240 and implements the steps of the method described above in combination with the hardware of the processor 1210.

[0355] In possible implementations, the communication interface 1230 is configured to perform the receiving and transmitting steps of the first network element in the embodiments shown in Figures 4 and 5. The processor 1210 is configured to perform the processing steps of the first network element in the embodiments shown in Figures 4 and 5.

[0356] In other possible implementations, the communication interface 1230 is configured to perform the receiving and transmitting steps of the second network element in the embodiments shown in Figures 4 and 5. The processor 1210 is configured to perform the processing steps of the second network element in the embodiments shown in Figures 4 and 5.

[0357] In one aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions. When an instruction is executed, the function performed by the second network element in Figures 4 and 5 is implemented.

[0358] In one aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions. When an instruction is executed, the function performed by the first network element in Figures 4 and 5 is implemented.

[0359] In one aspect, a computer program product containing instructions is provided. The computer program product contains instructions. When the instructions are executed, the functions performed by the second network element in Figures 4 and 5 are implemented.

[0360] In one aspect, a computer program product containing instructions is provided. The computer program product contains instructions. When the instructions are executed, the functions performed by the first network element in Figures 4 and 5 are implemented.

[0361] In one aspect, a chip is provided. The chip is used in a first network element. The chip includes at least one processor and a communication interface. The communication interface is coupled to at least one processor. The processor is configured to execute instructions in order to implement the functions performed by the first network element in Figures 4 and 5.

[0362] In one aspect, a chip is provided. The chip is used in a data analysis network element. The chip includes at least one processor and a communication interface. The communication interface is coupled to at least one processor. The processor is configured to execute instructions and implement the functions performed by the second network element in Figures 4 and 5.

[0363] This application provides a communication system. The communication system includes a first network element and a target device, the target device being either a first terminal or a second network element. The first network element is configured to perform the functions performed by the first network element in Figures 4 and 5, and the second network element is configured to perform the functions performed by the data analysis network element in Figures 4 and 5.

[0364] All or part of the embodiments described above may be implemented by software, hardware, firmware, or any combination thereof. When software is used for implementation, all or part of the embodiments may be implemented in the form of a computer program product. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded onto a computer and executed, all or part of the procedures or functions in the embodiments of the present application are performed. The computer may be a general-purpose computer, a dedicated computer, a computer network, a network device, a user device, or other programmable device. The computer program or instruction may be stored on a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, a computer program or instruction may be transmitted by wire or wirelessly from one website, computer, server, or data center to another 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 that integrates one or more available media, such as a server or data center. The usable media may be magnetic media, such as floppy disks, hard disks, or magnetic tapes; optical media, such as digital video discs (DVDs); or semiconductor media, such as solid-state drives (SSDs).

[0365] While this application is described with reference to embodiments, a person skilled in the art can understand and implement other modifications of the disclosed embodiments by looking at the accompanying drawings, the disclosed content and the accompanying claims in the process of implementing this application for which protection is claimed. In the claims, “comprising” does not exclude other components or other steps, and “one (a)” or “one” does not exclude multiple cases. A single processor or other unit may implement some of the functions enumerated in the claims. Although some means are recorded in different dependent claims, this does not mean that these means cannot be combined to produce a better effect.

[0366] While this application is described with reference to certain features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, the specification and accompanying drawings are merely illustrative descriptions of this application as defined by the accompanying claims and are considered to be any or all of the modifications, variations, combinations or equivalents that cover the scope of this application. It is evident that a person skilled in the art can make various modifications and variations of this application without departing from the spirit and scope of this application. This application intends to encompass these modifications and variations of this application, provided that they fall within the scope of protection defined by the following claims and their equivalent art.

Claims

1. A communication method, wherein the method is A step of determining that a first terminal has been disassociated from a first terminal set by a first network element, wherein the first terminal set includes one or more terminals, and the one or more terminals access a first edge application server or a first data network access identifier, A method comprising the step of, when the first network element determines that the first terminal has been disassociated from the first terminal set, the first network element transmits a protocol data unit PDU session change command to the first terminal that carries first instruction information, wherein the first instruction information is edge application server rediscovery instruction information.

2. The method according to claim 1, wherein the first instruction information instructs the first terminal to clear the cached edge application server information.

3. The method according to claim 1, wherein the first instruction information further instructs the first terminal to clear the domain name system cache, or the first network element transmits instruction information to the first terminal to clear the domain name system cache.

4. A communication method, wherein the method is A step of determining that a first terminal has been disassociated from a first terminal set by a first network element, wherein the first terminal set includes one or more terminals, and the one or more terminals access a first edge application server or a first data network access identifier, The method according to claim 1, further comprising the step of the first network element determining that the first terminal has been disassociated from the first terminal set, and the first network element transmitting a second data network access identifier of the first terminal to a second network element.

5. The aforementioned method, The method according to claim 4, further comprising the step of determining the second data network access identifier by the first network element when the first terminal is unassociated from the first terminal set.

6. The method according to claim 5, wherein the first terminal is unassociated from the first terminal set, the first edge application server or the edge application server corresponding to the first data network access identifier is not suitable for providing services to the first terminal, and the first network element determines the second data network access identifier.

7. The step of determining that the first terminal has been disassociated from the first terminal set by the first network element is: The first network element receives second instruction information, The method according to any one of claims 1 to 6, comprising the step of determining, based on the second instruction information, that the first terminal has been disassociated from the first terminal set by the first network element.

8. Before the first network element determines that the first terminal has been disassociated from the first terminal set, the method: The steps include receiving a first message by the first network element, wherein the first message includes an identifier for the first set of terminals and third instruction information, the third instruction information indicating that each terminal in the first set of terminals needs to access the first edge application server or the first data network access identifier; The first network element receives a second message, the second message does not contain the identifier of the first terminal set and / or the third instruction information, or the second message contains the second instruction information, the second instruction information indicating that the first terminal has been disassociated from the first terminal set. The step of determining that the first terminal has been disassociated from the first terminal set by the first network element is: The method according to any one of claims 1 to 6, comprising the step of determining, based on the first message and the second message, that the first terminal has been disassociated from the first terminal set, by the first network element.

9. The method according to claim 8, wherein the first message further includes a third identifier, the third identifier being used to determine the service associated with the first set of terminals.

10. The aforementioned method, The method according to any one of claims 1 to 9, further comprising the step of transmitting a fourth instruction information to a second network element by the first network element, the fourth instruction information being used to request the second network element to select a second edge application server for the first terminal.

11. The aforementioned method, The method according to any one of claims 1 to 10, further comprising the step of receiving edge application server address substitution information by the first network element, wherein the edge application server address substitution information is used by the first terminal to access the second edge application server.

12. The method according to claim 8, wherein the second message received by the first network element includes an identifier for a second set of terminals, and multiple terminals in the second set of terminals need to access a third edge application server or a third data network access identifier.

13. A communication method, wherein the method is A second network element determines that a first terminal has been disassociated from a first terminal set, wherein the first terminal set includes one or more terminals, and the one or more terminals access a first edge application server or a first data network access identifier. A method comprising the steps of: when the second network element determines that the first terminal has been disassociated from the first terminal set, the second network element determines a second edge application server corresponding to the first terminal, or transmits edge application server rediscovery-related instruction information or edge application server relocation-related information to the first network element.

14. The aforementioned method, The method according to claim 13, further comprising the step of determining a second data network access identifier of the first terminal using the second network element.

15. The step of determining the second data network access identifier of the first terminal using the second network element is: The second network element requests the second data network access identifier of the first terminal from the first network element, The method according to claim 14, further comprising the step of receiving the second data network access identifier from the first network element via the second network element.

16. The step of requesting the second data network access identifier of the first terminal from the first network element by the second network element is: The method according to claim 15, comprising the step of transmitting a fifth instruction information to the first network element by the second network element, wherein the fifth instruction information is used to request the second data network access identifier of the first terminal.

17. After determining the second edge application server corresponding to the first terminal using the second network element, the method proceeds as follows: The method according to any one of claims 13 to 16, further comprising the step of transmitting edge application server address substitution information to the first network element by the second network element, wherein the edge application server address substitution information is used by the first terminal to connect to the second edge application server.

18. A communication device, the device including a communication module and a processing module, The processing module is configured to perform a processing action performed by the first network element in the communication method described in any one of claims 1 to 12, and the communication module is configured to perform a receiving action or a transmitting action performed by the first network element in the communication method described in any one of claims 1 to 12. or The processing module is configured to perform a processing action performed by the second network element in the communication method described in any one of claims 13 to 17, and the communication module is configured to perform a receiving action or a transmitting action performed by the second network element in the communication method described in any one of claims 13 to 17, in the apparatus.

19. A communication system comprising a first network element and a target device, wherein the target device is a first terminal or a second network element. A communication system in which the first network element is configured to implement the communication method described in any one of claims 1 to 12, and the target device is configured to reselect an edge application server for the first terminal.

20. A communication system, wherein the system includes a second network element and a first network element. A communication system in which the second network element is configured to implement the communication method described in any one of claims 13 to 17, and the first network element is configured to provide a second data network identifier for the second network element.

21. A chip comprising at least one processor and a memory communicated with the at least one processor, A chip comprising: memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 12 or any one of claims 13 to 17.

22. A computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is set to be executed, the method according to any one of claims 1 to 12 or the method according to any one of claims 13 to 17 is performed.

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