Communication method, and apparatus

Abstract

The present application relates to the technical field of communications. Provided are a communication method, and an apparatus. In the method, when a terminal is located at a first position, a first session management network element used for acquiring subscription information of the terminal can receive a first message of a second session management network element that supports local offloading, and, when the terminal moves from the first position to a second position, the first session management network element can further receive a second message of a third session management network element that does not support local offloading, so as to send to the terminal a domain name server address on the basis of the first message and the second message. In this way, when the position of a terminal has changed and an intermediate session management network element serving the terminal has been switched, in the case where an intermediate session management network element after the switching does not support local offloading and therefore cannot configure an edge application discovery network element for a session of the terminal, a new domain name server address can be allocated to the terminal to provide a service for the terminal, so as to ensure continuity of the session of the terminal without interruption, thereby ensuring use experience of users.

Description

Communication method and apparatus

[0001] The present application claims priority from the Chinese patent application No. 202411392322.5 filed on September 30, 2024, and entitled "Communication method and apparatus", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication, in particular to a communication method and apparatus. BACKGROUND

[0003] In the research of R19 version of the 3rd generation partnership project (3GPP), when a user equipment (UE) moves and an intermediate session management function (I-SMF) network element is switched, since R19 is a non-roaming scenario, some I-SMF network elements can support local splitting (for example, an edge application server discovery function (EASDF) network element is configured), and some I-SMF network elements cannot support local splitting. Therefore, the address of the domain name server (DNS) configured for the UE is still the address of the DNS configured for the UE by the I-SMF network element before the switching.

[0004] After the I-SMF network element is switched, the I-SMF network element before the switching is deleted, so the address of the DNS configured for the UE by the I-SMF network element before the switching cannot provide services for the UE, and the address of the DNS configured for the UE is unavailable after the I-SMF network element is switched, thereby failing to guarantee the use experience of the user. SUMMARY

[0005] Embodiments of the present application provide a communication method and apparatus to achieve the following purposes: when a terminal moves and is served by an intermediate session management function network element that does not support local splitting, the address of a domain name server is re-allocated for the terminal, thereby guaranteeing the continuity of the terminal service and the use experience of the user.

[0006] To achieve the above purposes, the present application adopts the following technical solutions:

[0007] In a first aspect, a communication method is provided. The method comprises: receiving, by a first session management network element, a first message from a second session management network element, the first message being used to indicate that the second session management network element serves a first session of a terminal, the first session management network element serving the first session, the first session management network element being configured to obtain subscription information of the terminal, the second session management network element supporting local breakout, a service range of the second session management network element including a first location of the terminal, the first location being a location before the terminal moves; receiving, by the first session management network element, a second message from a third session management network element, the second message being used to indicate that the third session management network element serves the first session, the third session management network element not supporting local breakout, a service range of the third session management network element including a second location of the terminal, the second location being a location after the terminal moves; and sending, by the first session management network element, an address of a domain name server to the terminal according to the first message and the second message.

[0008] It can be understood that the first location is a location before the terminal moves, and the second location is a location after the terminal moves. It can be considered that the terminal moves from the first location to the second location, for example, the terminal moves from the service range of the second session management network element to the service range of the third session management network element.

[0009] Based on the above method, in a case where the terminal is located at the first location, the first session management network element serving the first session of the terminal and being configured to obtain the subscription information of the terminal can receive the first message of the second session management network element serving the first session of the terminal at the first location and supporting local breakout. In a case where the terminal moves from the first location to the second location, the first session management network element can also receive the second message of the third session management network element serving the first session of the terminal at the second location and not supporting local breakout. The first session management network element sends the address of the domain name server to the terminal according to the first message and the second message. In this way, in a case where the location of the terminal changes and the intermediate session management network element serving the terminal switches, the first session management network element can allocate a new address of a domain name server to the terminal to provide services for the terminal in a case where the intermediate session management network element after the switch does not support local breakout and cannot configure an edge application discovery network element for the session of the terminal, so as to ensure the continuity of the session of the terminal and prevent the session from being interrupted, thereby ensuring the user experience.

[0010] Optionally, the service range of the second session management network element includes the first location of the terminal, or the service range of the third session management network element includes the second location of the terminal. It can be understood that the service range of the session management network element is one or more tracking areas (TA), and the location of the terminal belongs to one of the TAs, or the service range of the session management network element is one or more data network access identifiers (DNAI) (also referred to as DNAI supported by the session management network element), and the location of the terminal corresponds to at least one DNAI.

[0011] For example, the session management network element (the first session management network element, the second session management network element, or the third session management network element) can determine that the current location of the terminal can access at least one DNAI, or the current location of the terminal is close to at least one DNAI. Alternatively, the DNAI can be mapped to a TA, and the current location of the terminal is in one or more TAs supported by the session management network element and mapped to the DNAI.

[0012] It should be noted that the first message sent by the second session management network element and the second message sent by the third session management network element can be different, and the proof message (the first message or the second message) can also be different in the way of indicating the first session of the terminal served by the session management network element. For example, the first message is an Nsmf_PDUSession_Create message, and the second message is an Nsmf_PDUSession_Update message. For example, when the message is a session update message (for example, an Nsmf_PDUSession_Update message), the session management context identifier (for example, an SM context ID) in the message can be used to determine the first session of the terminal served by the session management network element; when the message is a session creation message (for example, an Nsmf_PDUSession_Create message), the session identifier (for example, a PDU session ID) in the message can be used to determine the first session of the terminal served by the session management network element.

[0013] Optionally, the first session management network element can be an SMF or an anchor SMF of the first session, and the second and third session management network elements can be I-SMFs of the first session. The movement of the terminal can be reflected by a description of the network element, for example, according to the source I-SMF and the target I-SMF, it can be reflected that the terminal has moved, or according to the flow being a handover flow of the terminal, it can be reflected that the terminal has moved, and the present application does not limit this. For example, the second session management network element is a source I-SMF network element, and the third session management network element is a target I-SMF network element, which proves that the second session management network element is an SMF serving the UE before the UE moves, and the third session management network element is an SMF serving the UE after the UE moves.

[0014] In a possible design, the method further includes: determining, by the first session management network element, according to the first message, that the second session management network element supports local splitting; and determining, by the first session management network element, according to the second message, that the third session management network element does not support local splitting.

[0015] Optionally, the first message includes information indicating that the second session management network element supports local splitting, for example, any one or more of the following: a local DNS server IP address, an EASDF IP address, an EAS rediscovery indication, an impact field indicating that the terminal performs EAS rediscovery, and an offload identifier. The features of these information elements are that the session management network element supporting local splitting sends the information to the anchor session management network element of the session when serving the session as an intermediate session management network element. The session management network element not supporting local splitting does not send these information elements. Therefore, the present application does not limit that the second session management network element supporting local splitting can only be indicated by the above information elements, and any information element meeting the above features can be used to indicate that the second session management network element supports local splitting.

[0016] When the information indicating that the third session management network element supports local splitting is not included in the second message, it can be considered that the third session management network element does not support local splitting. Correspondingly, when any one or more of the information elements satisfying the above characteristics are used to indicate that the second session management network element supports local splitting, the absence of the one or more information elements in the second message can indicate that the third session management network element does not support local splitting. Thus, in this case, since the third session management network element does not support local splitting, the edge application discovery network element cannot be configured for the terminal, and at this time, since the second session management network element no longer serves the terminal, the address of the domain name server provided by the second session management network element for local access of the first session is no longer valid, and therefore the first session management network element needs to configure the address of the domain name server for the terminal to support local access of the first session. Thus, the session continuity of the terminal is ensured without interruption.

[0017] The EAS rediscovery indication and impact field are used to instruct the terminal to clear / update the locally stored DNS cache. The offload identifier is used by the I-SMF to indicate the SMF to store the splitting information / policy (for example, local offloading information / policy) on the I-SMF, which is used to indicate the traffic allowed by the I-SMF to perform local splitting.

[0018] Optionally, the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message, including: in the case that the second session management network element supports local splitting and the third session management network element does not support local splitting, the first session management network element sends the address of the domain name server to the terminal. For example, the first session management network element can determine from the first message that the second session management network element supports local splitting, and determine from the second message that the third session management network element does not support local splitting. In this case, the first session management network element sends the address of the domain name server to the terminal, so as to ensure the session continuity of the terminal without interruption based on the address of the domain name server. Thus, when the first session management network element needs to configure the address of the domain name server for the terminal, the address of the domain name server is sent to the terminal, so as to avoid complex signaling procedures or sending multiple addresses to the terminal.

[0019] In a possible design, when the second session management network element does not support local splitting and the third session management network element does not support local splitting, the first session management network element can also send the address of the domain name server to the terminal. In this case, the address of the domain name server sent by the first session management network element to the terminal is consistent with the address already configured in the terminal.

[0020] In a possible design, the support for the local offloading includes: configuring, for the first session, an edge application discovery network element, where the edge application discovery network element is configured to select an address of a local edge application server (EAS) for the first session, and the address is used for local access of the first session.

[0021] It can be understood that the support for the local offloading by the session management network element includes: the session management network element supports configuring, for a session of a terminal, an edge application discovery network element, so that the edge application discovery network element configured for the session of the terminal can select an address of an edge application server for the session of the terminal, to support local access of the session. Alternatively, the session management network element supports configuring, as an intermediate session management network element (I-SMF) of a session, local access of a session of a terminal, for example, configuring a splitting point (ULCL, uplink classifier / BP, branching point) for a session of a terminal, and selecting an edge application server.

[0022] Optionally, after the first session management network element receives the first message from the second session management network element, the method further includes: in response to the first message, the first session management network element sends, to the terminal, the address of the configured edge application discovery network element. For example, the first session management network element receives the first message from the second session management network element when the terminal moves into a service range of the second session management network element before the terminal moves from a service range of the second session management network element to a service range of the third session management network element. The first message includes the address of the configured edge application discovery network element.

[0023] In a possible design, the first message includes the address of the edge application discovery network element configured by the second session management network element for the first session, and the second message does not include the address of the edge application discovery network element.

[0024] In a possible design, the first session management network element sends, to the terminal, the address of the domain name server according to the first message and the second message, including: the first session management network element sends, to the terminal, the address of the domain name server according to that the first message includes the address of the edge application discovery network element configured by the second session management network element for the first session, and the second message does not include the address of the edge application discovery network element. In this way, the address of the domain name server can be sent to the terminal only when the session management network element corresponding to the location where the terminal moves after the movement does not send the address of the edge application discovery network element to the first session management network element. This ensures that the terminal has a usable address of the domain name server configured, and avoids interruption of the session of the terminal.

[0025] It can be understood that when the first message comprises the address of the edge application discovery network element configured by the second session management network element for the first session, it indicates that the second session management network element supports local offloading, and when the second message does not comprise the address of the edge application discovery network element, it indicates that the third session management network element does not support local offloading, at this time, the first session management network element can send the address of the domain name server to the terminal. In the case that the third session management network element cannot configure the edge application discovery network element for the first session of the terminal, the address of the domain name server can be configured for the terminal through the first session management network element.

[0026] In a possible design, the first session management network element, the second session management network element and the third session management network element belong to the same network. For example, the scenario of the present application is a non-roaming scenario of the terminal.

[0027] In a possible design, the first message comprises information of a first area, and the first area is an area supported by the second session management network element, and the second message comprises information of a second area, and the second area is an area supported by the third session management network element. In this way, by determining the areas supported by the session management network elements, in combination with the service area subscribed by the terminal, it can be determined whether the session management network element corresponding to the location of the terminal supports updating the address of the domain name server configured in the terminal. Whether the address of the domain name server is configured for the terminal is determined. In order to ensure that the terminal is configured with a usable address of the domain name server, and to avoid the interruption of the session of the terminal.

[0028] It should be noted that the area supported by the session management network element can be understood as one or more supported DNAI(s) of the session management network element, or a service area of the session management network element.

[0029] In a possible design, the first session management network element determines, according to the first message, that the second session management network element supports local offloading, comprising: the first session management network element determines, according to the first message, that the first area overlaps with the third area, and determines that the second session management network element supports local offloading, and the third area is a service area subscribed by the terminal.

[0030] It should be noted that the first area overlapping with the third area can be considered that the third area comprises part or all of the first area, for example, the third area comprises the complete first area, or the third area comprises part of the first area. For example, the first area comprises A area, B area and C area, and the second area comprises A area and B area, so the first area overlaps with the third area, and the third area comprises all of the first area; or, the first area comprises A area, B area and C area, and the second area comprises A area, so the first area overlaps with the third area, and the third area comprises part of the first area.

[0031] In a possible design, the first session management network element determines, according to the second message, that the third session management network element does not support local splitting, including: the first session management network element determines, according to the second message, that the second area and the third area do not overlap, and determines that the third session management network element does not support local splitting, the third area being a service area of the terminal.

[0032] Similarly, the second area and the third area do not overlap can mean that the third area does not include any part of the second area. For example, the first area includes: an A area, a B area and a C area, and the second area includes: a D area and an E area, the second area and the third area do not overlap, and the third area does not include any part of the second area.

[0033] In a possible design, the first session management network element sends, according to the first message and the second message, the address of the domain name server to the terminal, including: the first session management network element sends, according to that the first area and the third area overlap and the second area and the third area do not overlap, the address of the domain name server to the terminal, the third area being a service area of the terminal.

[0034] It can be understood that the first area and the third area overlap can mean that the second session management network element supports local splitting, and the second area and the third area do not overlap means that the third session management network element does not support local splitting. In this case, the third session management network element cannot configure the edge application discovery network element for the first session of the terminal, and needs to configure the address of the domain name server for the terminal through the first session management network element.

[0035] In a possible design, the method further includes: the first session management network element obtains information of the third area from a data management network element. For example, information of a service area of the terminal can be obtained from a unified data management (UDM) network element serving the terminal (the first session of the terminal).

[0036] In a possible design, the address of the domain name server is an address of a default domain name server or an address of a central domain name server. Alternatively, the address of the domain name server can also be another address, as long as the terminal can successfully resolve a service accessed by the terminal through the domain name server.

[0037] Optionally, the address of the default domain name server or the address of the central domain name server is an address locally configured or stored by the first session management network element, or an address obtained from a unified data repository (UDR) network element.

[0038] Optionally, the method further comprises: the first session management network element obtaining authorization information of the terminal, the authorization information being used to indicate that the session of the terminal is allowed to be locally split; and the first session management network element sending the address of the domain name server to the terminal according to the first message and the second message, including: based on the authorization information, the first session management network element sending the address of the domain name server to the terminal according to the first message and the second message.

[0039] It can be understood that the authorization information of the terminal is included in the context of the first session when the first session of the terminal is established. Therefore, before the first session management network element sends the address of the domain name server to the terminal, the first session management network element can further judge the authorization information of the terminal, so that the address of the domain name server is sent to the terminal only when the authorization information of the terminal indicates that the session of the terminal is allowed to be locally split. If the authorization information of the terminal indicates that the session of the terminal is not allowed to be locally split, the address of the domain name server will not be sent to the terminal. Therefore, the accuracy of sending the address of the domain name server to the terminal is further ensured, and the situation of sending multiple addresses of domain name servers to the terminal is avoided.

[0040] Optionally, after the first session management network element receives the first message from the second session management network element, the method further comprises: saving a first result indicating that the second session management network element supports local splitting; and the first session management network element sending the address of the domain name server to the terminal according to the first message and the second message, including: the first session management network element sending the address of the domain name server to the terminal based on the first result and the second message.

[0041] Similarly, after the first session management network element receives the second message from the third session management network element, the method can further comprise: saving a second result indicating that the third session management network element does not support local splitting. In this way, the first session management network element can determine to send the address of the domain name server to the terminal based on the first result and the second result.

[0042] It can be understood that after the first session management network element receives the first message from the second session management network element, the first session management network element can determine whether the second session management network element supports local splitting according to the first message, and save the result of the determination (for example, the first result). Therefore, when determining whether to send the address of the domain name server to the terminal, the saved first result can be directly used for judgment, without the need to store the first message and reanalyze the first message, thereby improving the efficiency of data information processing.

[0043] In a second aspect, a communication method is provided, which is applied to a second session management network element. The method comprises: in a case where a terminal moves to a first location, the second session management network element sends a first message to a first session management network element, the first location is a location in a service range of the second session management network element, the first message is used to indicate a first session of the terminal served by the second session management network element, the second session management network element supports local offloading, and the first message comprises an address of an edge application discovery network element configured by the second session management network element; the first session management network element serves the first session, and the first session management network element is used to acquire subscription information of the terminal.

[0044] In addition, the method of the second aspect has the same effects as those of the first aspect, which will not be repeated.

[0045] In a third aspect, a communication method is provided, which is applied to a third session management network element. The method comprises: in a case where a terminal moves from a first location to a second location, the third session management network element sends a second message to a first session management network element, the first location is a location in a service range of a second session management network element, the second location is a location in a service range of the third session management network element, the second message is used to indicate a first session of the terminal served by the third session management network element, the second session management network element serves the first session of the terminal, the second session management network element supports local offloading, the third session management network element does not support local offloading, the first session management network element serves the first session, and the first session management network element is used to acquire subscription information of the terminal; and the third session management network element receives an address of a domain name server from the first session management network element, and sends the address of the domain name server to the terminal.

[0046] Optionally, the third session management network element can parse the received address of the domain name server and forward it to the terminal, or transparently transmit the address of the domain name server to the terminal without parsing.

[0047] In addition, the method of the third aspect has the same effects as those of the first aspect, which will not be repeated.

[0048] In a fourth aspect, a communication apparatus is provided. The communication apparatus comprises modules for performing the method of any one of the first aspect to the third aspect, such as a transceiver module and a processing module. For example, the transceiver module is used to indicate the transceiving function of the communication apparatus, and the processing module is used to perform the function of the communication apparatus other than the transceiving function.

[0049] Optionally, the transceiver module can comprise a sending module and a receiving module. The sending module is used to implement the sending function of the communication apparatus of the fourth aspect, and the receiving module is used to implement the receiving function of the communication apparatus of the fourth aspect.

[0050] Optionally, the communication apparatus in the fourth aspect can further include a storage module, which stores programs or instructions. When the processing module executes the programs or instructions, the communication apparatus can execute the method in any one of the first aspect to the third aspect.

[0051] It can be understood that the communication apparatus in the fourth aspect can be a network device, a chip (system) or other components or assemblies that can be arranged in the network device, or an apparatus including the network device, which are not limited in the present application.

[0052] In addition, the technical effects of the communication apparatus in the fourth aspect can refer to those of the other aspects, which will not be repeated.

[0053] In the fifth aspect, a communication apparatus is provided. The communication apparatus includes a processor configured to execute the method in any one of the first aspect to the third aspect.

[0054] In a possible design, the communication apparatus in the fifth aspect can further include a transceiver. The transceiver can be a transceiver circuit or an interface circuit. The transceiver can be configured to enable the communication apparatus in the fifth aspect to communicate with other communication apparatuses.

[0055] In a possible design, the communication apparatus in the fifth aspect can further include a memory. The memory can be integrated with the processor, or can be arranged separately. The memory can be configured to store computer programs and / or data related to the method in any one of the first aspect to the third aspect.

[0056] In the embodiments of the present application, the communication apparatus in the fifth aspect can be the network device in any one of the first aspect to the third aspect, or a chip (system) or other components or assemblies that can be arranged in the network device, or an apparatus including the network device.

[0057] In addition, the technical effects of the communication apparatus in the fifth aspect can refer to those of the other aspects, which will not be repeated.

[0058] In the sixth aspect, a communication apparatus is provided. The communication apparatus includes a processor coupled with a memory, and the processor is configured to execute computer programs stored in the memory, so that the communication apparatus executes the method in any one of the first aspect to the third aspect.

[0059] In a possible design, the communication apparatus in the sixth aspect can further include a transceiver. The transceiver can be a transceiver circuit or an interface circuit. The transceiver can be configured to enable the communication apparatus in the sixth aspect to communicate with other communication apparatuses.

[0060] In embodiments of the present application, the communication apparatus of the sixth aspect can be the network device of any one of the first aspect to the third aspect, or a chip (system) or other component or assembly that can be disposed in the network device, or an apparatus including the network device.

[0061] In addition, the technical effects of the communication apparatus of the sixth aspect can refer to the technical effects of the other aspects described above, and will not be repeated.

[0062] The seventh aspect provides a communication apparatus, including a processor and a memory; the memory is used to store a computer program, when the processor executes the computer program, to make the communication apparatus execute the method of any one of the first aspect to the third aspect.

[0063] In a possible design, the communication apparatus of the seventh aspect can further include a transceiver. The transceiver can be a transceiver circuit or an interface circuit. The transceiver can be used for the communication apparatus of the seventh aspect to communicate with other communication apparatuses.

[0064] In embodiments of the present application, the communication apparatus of the seventh aspect can be the network device of any one of the first aspect to the third aspect, or a chip (system) or other component or assembly that can be disposed in the network device, or an apparatus including the network device.

[0065] In addition, the technical effects of the communication apparatus of the seventh aspect can refer to the technical effects of the other aspects described above, and will not be repeated.

[0066] The eighth aspect provides a communication system. The communication system includes at least one of the first session management network element of the first aspect, the second session management network element of the second aspect, or the third session management network element of the third aspect.

[0067] The ninth aspect provides a computer readable storage medium, including a computer program or instructions; when the computer program or instructions run on a computer, the computer program or instructions make the computer execute the method of any one of the first aspect to the third aspect.

[0068] The tenth aspect provides a computer program product, including a computer program or instructions; when the computer program or instructions run on a computer, the computer program or instructions make the computer execute the method of any one of the first aspect to the third aspect. BRIEF DESCRIPTION OF DRAWINGS

[0069] FIG. 1 is a schematic diagram of the architecture of a 5GS;

[0070] FIG. 2 is a schematic diagram of the architecture of a 5GS with an I-SMF network element inserted;

[0071] FIG. 3 is a schematic diagram of a multi-anchor session architecture;

[0072] FIG. 4 is a schematic diagram of an architecture of a communication system according to an embodiment of the present application;

[0073] FIG. 5 is a schematic diagram of an architecture of a communication system according to an embodiment of the present application;

[0074] FIG. 6 is a schematic diagram of a communication method according to an embodiment of the present application;

[0075] FIG. 7 is a schematic diagram of a communication method according to an embodiment of the present application;

[0076] FIG. 8 is a schematic diagram of a communication method according to an embodiment of the present application;

[0077] FIG. 9 is a schematic diagram of a communication apparatus according to an embodiment of the present application;

[0078] FIG. 10 is a schematic diagram of a communication apparatus according to an embodiment of the present application. DETAILED DESCRIPTION

[0079] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as a wireless network (Wi-Fi) system, a vehicle to everything (V2X) communication system, a device to device (D2D) communication system, a vehicle networking communication system, a 4th generation (4G) mobile communication system such as a long term evolution (LTE) system, a worldwide interoperability for microwave access (WiMAX) communication system, a 5th generation (5G) mobile communication system such as a new radio (NR) system, and a future communication system.

[0080] For the convenience of understanding, the technical terms related to the embodiments of the present application are introduced as follows.

[0081] 1. 5th generation (5G) mobile communication system (5G system, 5GS):

[0082] FIG. 1 is a schematic diagram of an architecture of a 5GS. As shown in FIG. 1, the 5GS includes an access network (AN), a core network (CN), and a data network (DN), and can also include a terminal.

[0083] The terminal can be one or more, such as a first terminal, a second terminal, a third terminal, and the like. The terminal can be a terminal having a transceiver function, or can also be a chip or chip system provided in the terminal. The terminal can also be referred to as a user equipment (UE), an access terminal, a subscriber unit, a user station, a mobile station (MS), a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent, or a user apparatus. The terminal in the embodiments of the present application can be a mobile phone, a cellular phone, a smart phone, a Pad, a wireless data card, a personal digital assistant computer (PDA), a wireless modem, a handset, a laptop computer, a machine type communication (MTC) terminal, a computer with a wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a smart home device (for example, a refrigerator, a television, an air conditioner, an electricity meter, and the like), a smart robot, a mechanical arm, a plant device, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical treatment, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a vehicle-mounted terminal, a road side unit (RSU) with a terminal function, and the like, a flight device (for example, a smart robot, a hot air balloon, a drone, an airplane), and the like. The terminal of the present application can also be a vehicle-mounted module, a vehicle-mounted module, a vehicle-mounted component, a vehicle-mounted chip, or a vehicle-mounted unit built in a vehicle as one or more components or units. The terminal device can also be other devices with terminal functions, for example, the terminal device can also be a device with terminal functions in D2D communication.

[0084] Embodiments of the present application do not limit the device form of the terminal, and the device for implementing the function of the terminal device can be a terminal device; or can be a device capable of supporting the terminal device to implement the function, such as a chip system. The device can be installed in the terminal device or used in matching with the terminal device. In embodiments of the present application, the chip system can be composed of a chip, or can include a chip and other discrete devices.

[0085] The AN described above is used to implement access-related functions, can provide network access functions for authorized users in a specific area, and can determine transmission links of different qualities to transmit user data according to the level of a user, the demand of a service, and the like. The AN forwards control signals and user data between a terminal and a CN. The AN can include an access network device, which can also be referred to as a radio access network (RAN) device. The CN is mainly responsible for maintaining subscription data of a mobile network, and provides functions such as session management, mobility management, policy management, and security authentication for a terminal. The CN mainly includes the following network elements: a user plane function (UPF) network element, an authentication server function (AUSF) network element, an access and mobility management function (AMF) network element, a session management function (SMF) network element, a network slice selection function (NSSF) network element, a network exposure function (NEF) network element, a network function repository function (NRF) network element, a policy control function (PCF) network element, a unified data management (UDM) network element, a unified data repository (UDR) network element, and an application function (AF) network element.

[0086] It should be noted that the UPF network element is mainly responsible for processing user messages, such as forwarding, charging statistics, etc. The UPF network element directly connected with the DN in the session through N6 can be referred to as a protocol data unit (PDU) session anchor (PSA), and the anchor UPF network element of local splitting can be referred to as a local PDU session anchor (L-PSA). The UPF network element as a splitting point can be referred to as an uplink classifier (ULCL) or a branching point (BP).

[0087] The RAN device, i.e., the access network device, can be one or more. The access network device can be a device with wireless transceiving function, or also can be a chip or chip system arranged in the device, located in the access network (AN) of the communication system, and used to provide access services for terminals. For example, the access network device can be referred to as a radio access network (RAN) device, and specifically can be an access network device of a future mobile communication system, such as a base station of a future mobile communication system, or in a future mobile communication system, the access network device can also have other naming ways, which are all included in the protection scope of the embodiments of the present application, and the present application does not make any limitation on this. Or, the access network device can also include a gNB in 5G, such as a new radio (NR) system, or one or a group (including multiple antenna panels) of antenna panels of a base station in 5G, or can also be a network node constituting a gNB, a transmission and reception point (TRP or transmission point, TP), or a transmission measurement function (TMF), such as a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), an RSU with base station function, or a wired access gateway, or a core network element of 5G, etc. Or, the access network device can also include an access point (AP) in a wireless fidelity (WiFi) system, a wireless relay node, a wireless backhaul node, various forms of macro base stations, micro base stations (also referred to as small stations), relay stations, access points, wearable devices, vehicle-mounted devices, etc.

[0088] The CU and the DU can be separately arranged, or can also be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH). It can be understood that the network device can be a CU node, or a DU node, or a device including a CU node and a DU node. In addition, the CU can be divided into a network device in an access network RAN, or the CU can be divided into a network device in a core network CN, which is not limited herein.

[0089] The CU (or CU-CP and CU-UP), DU, or RU can also have different names in different systems, but those skilled in the art can understand their meanings. For example, in an ORAN system, the CU can also be referred to as an O-CU (open CU), the DU can also be referred to as an O-DU, the CU-CP can also be referred to as an O-CU-CP, the CU-UP can also be referred to as an O-CU-UP, and the RU can also be referred to as an O-RU. For the convenience of description, the CU, CU-CP, CU-UP, DU, and RU are taken as examples for description in the present application. Any one of the CU (or CU-CP, CU-UP), DU, and RU in the present application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0090] The UPF network element is mainly responsible for user data processing (forwarding, receiving, charging, etc.). For example, the UPF network element can receive user data from a data network (DN) and forward the user data to a terminal through an access network device. The UPF network element can also receive user data from the terminal through the access network device and forward the user data to the DN. The DN network element refers to an operator network that provides data transmission services for users. For example, an internet protocol (IP) multi-media service (IMS), the Internet, etc.

[0091] The DN can be an operator external network or an operator-controlled network, which is used to provide service services to terminal devices.

[0092] The AUSF network element is mainly used to perform security authentication of the terminal.

[0093] The AMF network element is mainly used for mobility management in a mobile network. For example, user location update, user registration network, user handover connection management, reachability management, etc. The specific functions are non-access layer signaling termination, registration area management, access authentication, etc.

[0094] The SMF network element is mainly used for session management in a mobile network. For example, session establishment, modification, release. The specific functions are, for example, user allocation of an internet protocol (IP) address, selection of a UPF network element providing packet forwarding functions, etc.

[0095] The PCF network element mainly supports providing a unified policy framework to control network behavior, providing policy rules to control layer network functions, and being responsible for obtaining user subscription information related to policy decision. The PCF network element can provide policies such as quality of service (QoS) policies and slice selection policies to the AMF network element and the SMF network element. And obtain subscription related information from the UDR network element to make policy decisions.

[0096] The NSSF network element is mainly used for selecting network slices for terminals.

[0097] The NEF network element is mainly used to support the opening of capabilities and events.

[0098] The UDM network element is mainly used to store user data, such as subscription data, authentication / authorization data, etc.

[0099] The UDR network element is mainly used to store structured data. The stored content includes subscription data and policy data, externally exposed structured data, and application related data.

[0100] The AF mainly supports interaction with the CN to provide services, such as affecting data routing decisions, policy control functions, or providing third-party services to the network side.

[0101] 2、5G network SMF and UPF enhancing topology (ETSUN) scenario

[0102] The ETSUN scenario describes a scenario where the SMF network element has a certain service area (SMF service area), and the SMF network element cannot control the UPF network element outside its service area. It can be understood that the service area can be one or more tracking areas (TAs). When the terminal moves to an area outside the service area of the SMF network element, the AMF network element triggers the insertion of the SMF network element capable of serving the current location (service area) of the terminal as an intermediate session management function (I-SMF) network element. As shown in FIG. 2, it is a schematic diagram of the architecture of the 5GS for inserting the I-SMF network element. After the I-SMF network element is inserted, the I-SMF network element inserts an intermediate user plane function (I-UPF) network element / ULCL / BP or L-PSA to ensure that the user plane of the session of the terminal can continue to be connected. For example, when the terminal moves to an area outside the service area of the SMF network element, the RAN device accessed by the terminal cannot be directly connected to the UPF network element (such as the PSA UPF network element) controlled by the SMF network element, and needs to be connected through the I-UPF network element / ULCL / BP or L-PSA. At this time, the I-UPF network element / ULCL / BP or L-PSA is controlled by the I-SMF network element, and the SMF network element can instruct the I-SMF network element to insert the I-UPF network element / ULCL / BP or L-PSA, but the SMF network element cannot directly control these I-UPF network elements / ULCL / BP or L-PSA because these I-UPF network elements / ULCL / BP or L-PSA are outside the service area of the SMF network element.

[0103] It should be noted that in the case of supporting splitting (with a splitting point), the architecture shown in FIG. 2 includes the ULCL / BP and the L-PSA, that is, the UPF connected with the I-SMF network element is the ULCL / BP, and the ULCL / BP is connected with the L-PSA; in the case of not supporting splitting (without a splitting point), the architecture shown in FIG. 2 includes the I-UPF network element, but does not include the ULCL / BP and the L-PSA, that is, the UPF connected with the I-SMF network element is the I-UPF network element, and the I-UPF network element is not connected with the L-PSA.

[0104] It should be noted that the I-SMF network element is the SMF network element that needs to be inserted to support the PDU session when the location of the terminal cannot be controlled by the initial SMF network element.

[0105] Further, if the terminal continues to move and moves out of the service area of the I-SMF network element (also referred to as a source I-SMF (source I-SMF) network element) and is still not within the service area of the SMF after the I-SMF network element is inserted, the AMF network element needs to trigger the replacement of the I-SMF network element again (retrigger the insertion of the SMF network element capable of serving the current location of the terminal as a new I-SMF network element, also referred to as a target I-SMF (target I-SMF) network element), for example, the session of the terminal is switched from being served by the source I-SMF network element to being served by the target I-SMF network element. Similarly, if the terminal moves back into the service area of the SMF network element, the AMF network element triggers the deletion of the I-SMF network element and switches the session of the terminal back to being served by only one SMF network element.

[0106] According to the content in 3GPP TS 23.502, if the session of the terminal has been inserted into the source I-SMF network element, when the terminal moves from the service area of the source I-SMF network element to the service area of the target I-SMF network element, the RAN device can send a path switching request message to the AMF network element. The AMF network element selects the target I-SMF network element and sends a session context setup message to the target I-SMF network element. Then the target I-SMF network element sets up the session context and sends a provide session context message to the source I-SMF network element, so that the source I-SMF network element sends a response message to the target I-SMF network element. The target I-SMF network element can configure the I-UPF network element based on the response message and send a session update message to the SMF network element. The SMF network element updates the PSA UPF according to the session update message and sends a session update response to the target I-SMF network element. So that the target I-SMF network element updates the UPF configuration and sends a session context setup response message to the AMF network element. And the AMF network element sends a path switching response message to the RAN device according to the session context setup response message to switch the I-SMF network element serving the session of the terminal.

[0107] 3. Multi-anchor session architecture

[0108] In a multi-anchor PDU session, in order to support selective traffic routing of a data network or support continuity of a session, the SMF network element can insert multiple UPF network elements controlled by the SMF network element in the user plane of the PDU session to control the user plane path of the PDU session, so that one PDU session can access a DN through multiple N6 interfaces at the same time. And each UPF network element accessing the DN needs to support the PDU session anchor function, for example, one PDU session needs to access the same DN through multiple anchors.

[0109] As shown in FIG. 3, in the multi-anchor session architecture, there is a UPF network element (e.g., ULCL / BP) as a splitting point, which has the function of splitting user plane messages according to the source / destination IP address of the user plane message, and the splitting rule is configured by the SMF network element. The SMF can control the insertion, modification and removal of the UPF network element through the N4 interface between the SMF and the UPF network element to configure / modify the splitting rule, etc. For example, the ULCL can split according to the destination IP address of the uplink message, and according to the destination IP address, the user plane message is forwarded to the C-PSA or L-PSA through different tunnels (the tunnel of the ULCL and the C-PSA (Central PSA, C-PSA), or the tunnel of the ULCL and the L-PSA). Or for example, the BP splits according to the source IP address of the uplink message.

[0110] 4. An edge application server (EAS) is discovered using an edge application server discovery function (EASDF) network element.

[0111] In an edge computing (EC) deployment scenario, some services can be provided by multiple EASs deployed at the edge of the network. These EASs can provide the same service and content, but have different IP addresses. When a terminal needs to access the service, the EC scenario requires the terminal to access the nearest available EAS. Therefore, the terminal needs to obtain the IP address of the appropriate EAS (e.g., the IP address of the EAS serving the location of the terminal). It should be noted that the IP address in this application can be an internet protocol version 4 (IPv4), an internet protocol version 6 (IPv6), a media access control (MAC) address, etc., and the type of address is not limited.

[0112] A new network element for assisting EAS discovery is defined in 3GPP standard TS23.548, such as EASDF network element, which mainly functions to process domain name system (DNS) messages according to the indication of the SMF network element. Specifically, it includes: reporting the DNS message to the SMF network element, adding an extended mechanism for DNS (EDNS) client subnet option (ECS option) in the DNS request message (such as DNS query), forwarding the DNS query to the DNS server, forwarding the DNS response message (DNS response) to the terminal, and the like.

[0113] Specifically, the flow of discovering EAS using the EASDF network element can refer to the definition of 3GPP standard TS23.548.

[0114] 5. In a roaming scenario, the V-EASDF network element is used to discover EAS.

[0115] In the discussion of R18 version, the flow of discovering EAS using the V-EASDF network element in a roaming scenario is introduced. In this scenario, the EASDF network element is configured by the V-SMF network element, so it can be called V-EASDF network element. For a roaming session, whether the V-EASDF network element can be used, an authorization process is introduced. Therefore, after the V-EASDF network element is configured, the address of the V-EASDF network element also needs to be sent to the terminal as the default DNS server. However, the message sent to the terminal can only be generated by the SMF network element or the H-SMF network element, so the address of the V-EASDF network element needs to be sent to the H-SMF network element by the V-SMF network element first, and then sent to the terminal by the H-SMF network element.

[0116] When the terminal moves in the visited public land mobile network (VPLMN), the replacement of the V-SMF network element may also occur, at which time the V-EASDF network element also needs to be replaced. That is, the target V-EASDF network element controlled by the target V-SMF network element is different from the source V-EASDF network element controlled by the source V-SMF network element.

[0117] When the V-SMF network element is replaced, the target V-EASDF network element needs to be updated to the terminal through the H-SMF network element. In this scenario, the replacement process of the V-SMF network element can refer to the content in 3GPP TS23.548.

[0118] In the discussion of 3GPP R19 version, it is hoped to combine the process of discovering EAS using EASDF network element with the network architecture of ETSUN scenario. Assuming that the configuration of EASDF network element needs to be completed by I-SMF network element, when the I-SMF network element is replaced, similar to the R18 roaming scenario, the address of the EASDF network element also needs to be updated to the terminal through the SMF network element. But since R19 is a non-roaming scenario, there may be some I-SMF network elements that can configure the address of the EASDF network element, and some I-SMF network elements that cannot configure the address of the EASDF network element. Therefore, when the I-SMF network element is replaced, the source I-SMF network element can configure the address of the EASDF network element, while the target I-SMF network element cannot configure the address of the EASDF network element. In this case, the address of the EASDF network element configured by the source I-SMF network element has been configured on the terminal as the default DNS server before, but after being replaced by the target I-SMF network element, since the target I-SMF network element cannot configure the address of the EASDF network element, the target I-SMF network element will not instruct the SMF network element to update the default DNS server of the terminal. The default DNS server configured on the terminal is still the address of the EASDF network element configured by the source I-SMF network element, but the source I-SMF network element has been deleted at this time, and the address of the EASDF network element configured by the source I-SMF network element is no longer served for the terminal, resulting in that the default DNS server of the terminal is unavailable after the I-SMF is replaced, so that the user experience cannot be guaranteed.

[0119] To solve the above technical problems, the embodiments of the present application propose the following technical solutions.

[0120] The technical solutions in the present application will be described below with reference to the drawings.

[0121] In the embodiments of the present application, the indication can include direct indication and indirect indication, and can also include explicit indication and implicit indication. The information indicated by certain information (e.g., the first indication information, the second indication information, or the third indication information, etc. below) is referred to as to-be-indicated information. In the implementation process, there are many ways to indicate the to-be-indicated information, for example, but not limited to, the to-be-indicated information can be directly indicated, such as the to-be-indicated information itself or an index of the to-be-indicated information, etc. The to-be-indicated information can also be indirectly indicated by indicating other information, where the other information and the to-be-indicated information have an association relationship. The to-be-indicated information can also be indicated only by a part of the to-be-indicated information, and the other part of the to-be-indicated information is known or agreed in advance. For example, the indication of a specific information can also be achieved by means of the arrangement order of each information agreed in advance (e.g., a protocol), thereby reducing the indication overhead to a certain extent. Meanwhile, a common part of each information can be identified and uniformly indicated, so as to reduce the indication overhead caused by separately indicating the same information.

[0122] In addition, the specific indication manner can also be various existing indication manners, for example, but not limited to, the above indication manners and various combinations thereof, etc. The specific details of various indication manners can refer to the prior art, which will not be described herein. As known from the above, for example, when multiple information of the same type needs to be indicated, the indication manners of different information can be different. In the implementation process, the required indication manner can be selected according to the specific needs, and the selected indication manner is not limited in the embodiments of the present application. In this way, the indication manner involved in the embodiments of the present application should be understood as covering various methods that can enable the to-be-indicated information to be known by the to-be-indicated party.

[0123] It should be understood that the to-be-indicated information can be sent as a whole, or can be divided into multiple sub-information and sent separately, and the sending period and / or sending occasion of the sub-information can be the same or different. The specific sending method is not limited in the embodiments of the present application. The sending period and / or sending occasion of the sub-information can be predefined, for example, predefined according to a protocol, or configured by the sending end device by sending configuration information to the receiving end device.

[0124] The predefinition or pre-configuration can be realized by pre-storing corresponding codes, tables or other means for indicating relevant information in the device, and the embodiments of the present application do not limit the specific implementation manner. The storage can be in one or more memories. The one or more memories can be separately arranged or integrated in the encoder or decoder, processor or communication device. The one or more memories can be partially separately arranged and partially integrated in the decoder, processor or communication device. The memory can be any form of storage medium, and the embodiments of the present application do not limit the same.

[0125] The protocol referred to in the embodiments of the present application can refer to a protocol family in the communication field, a standard protocol similar to the protocol family frame structure, or a relevant protocol applied to a future communication system, and the embodiments of the present application do not limit the same.

[0126] In the embodiments of the present application, the descriptions such as "when", "in the case of", "if" and "whether" all refer to that the device will make corresponding processing under certain objective condition, and are not limited in time, and do not require the device to have a judgment action when implemented, nor mean that there are other limitations.

[0127] In the description of the embodiments of the present application, unless otherwise specified, " / " represents that the objects before and after the " / " are in an "or" relationship, for example, A / B can represent A or B; "and / or" in the embodiments of the present application is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. And, in the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. "At least one of the following" or the like means any combination of the items, including any combination of single item or multiple items. For example, at least one of a, b or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, "first", "second", and the like are used to distinguish the same items or similar items with basically the same function and role. Those skilled in the art can understand that "first", "second", and the like do not limit the quantity and execution order, and "first", "second", and the like do not necessarily mean different. At the same time, in the embodiments of the present application, "exemplary" or "for example" means to present relevant concepts in a specific manner for understanding.

[0128] The network architecture and service scenarios described in the embodiments of the present application are used to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art can know that, with the evolution of network architecture and the appearance of new service scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0129] In order to understand the embodiments of the present application, first, the communication system shown in FIG. 4 is taken as an example to describe the communication system applicable to the embodiments of the present application in detail. For example, FIG. 4 is a schematic diagram of the architecture of a communication system applicable to the communication method provided by the embodiments of the present application.

[0130] As shown in FIG. 4, the communication system mainly includes: a terminal and a session management network element.

[0131] The terminal can be the terminal described in the above technical terms, which can be understood by reference, and will not be described here.

[0132] The session management network elements are multiple, such as a first session management network element, a second session management network element and a third session management network element. The session management network element can be an SMF network element, or in a future communication system, the session management network element can also be replaced by other network elements with corresponding functions.

[0133] In the communication system, in a case that the terminal is located at a first location, a first session (all the following first sessions are the first session of the terminal) serving the terminal and a first session management network element used to acquire subscription information of the terminal can receive a first message of a second session management network element which serves the first session of the terminal at the first location and supports local splitting. In a case that the terminal moves from the first location to a second location, the first session management network element can also receive a second message of a third session management network element which serves the first session of the terminal at the second location and does not support local splitting. According to the first message and the second message, an address of a domain name server is sent to the terminal. In this way, in a case that the location of the terminal changes and the intermediate session management network element serving the terminal switches, the first session management network element can allocate a new address of the domain name server to the terminal to provide services for the terminal, so as to ensure the continuity of the session of the terminal without interruption, thereby ensuring the user experience.

[0134] It should be noted that the first session management network element can acquire the subscription information of the terminal, while the second session management network element and the third session management network element cannot acquire the subscription information of the terminal and only serve as intermediate network elements to forward information.

[0135] Based on the communication system shown in FIG. 4, the communication system provided by the embodiments of the present application can be a specific system architecture as shown in FIG. 5. In the specific system architecture, in addition to the terminal and the session management network element shown in FIG. 4, other network elements for implementing the session function of the terminal can also be included. For example, an AMF network element, a RAN device, a DN, an EASDF network element, a PSA network element, an L-PSA network element, a ULCL / BP and an EAS. For specific descriptions of these network elements shown in FIG. 5, reference can be made to the descriptions of the system architectures shown in FIG. 2 and FIG. 3, which will not be repeated here.

[0136] It should be noted that in combination with the system architecture shown in FIG. 5, the first session management network element in the present application is an SMF network element, and the second session management network element and the third session management network element are I-SMF network elements. When the terminal is located at different locations, the second session management network element and the third session management network element can be different I-SMF network elements.

[0137] It should be noted that the application scenario of the present application is that the terminal moves to the service range of the second session management network element, and the second session management network element sends the first message to the first session management network element. Then, when the terminal moves from the service range of the second session management network element to the service range of the third session management network element, the third session management network element sends the second message to the first session management network element. Therefore, when the terminal is located in the service range of the second session management network element, the location of the terminal can be referred to as the first location, for example, the service range of the second session management network element includes the first location of the terminal, that is, the first location is the location before the terminal moves (from the service range of the second session management network element to the service range of the third session management network element).

[0138] For example, the terminal moves from the service range of a certain session management network element (which can be the first session management network element or another session management network element) to the service range of the second session management network element. Then, the terminal moves from the service range of the second session management network element to the service range of the third session management network element.

[0139] For the movement of the terminal between the service range of the first session management network element and the service range of the second session management network element, the present application is not limited, and specifically, the terminal can directly move from the service range of the first session management network element to the service range of the second session management network element; or the terminal can first move from the service range of the first session management network element to the service range of another session management network element (which is not the second session management network element), and then move from the service range of the another session management network element to the service range of the second session management network element.

[0140] For the movement of the terminal between the service range of the first session management network element and the service range of the second session management network element, the present application is not limited, and specifically, the terminal can directly move from the service range of the first session management network element to the service range of the second session management network element; or the terminal can first move from the service range of the first session management network element to the service range of another session management network element (which is not the second session management network element), and then move from the service range of the another session management network element to the service range of the second session management network element.

[0141] The interaction process between the network elements / devices in the communication system will be specifically introduced below by means of method embodiments in combination with FIGS. 6-8. The communication method provided by the embodiments of the present application can be applied to the above-mentioned communication system and specifically applied to various scenarios mentioned in the above-mentioned communication system, which will be specifically introduced below.

[0142] FIG. 6 is a flowchart of a communication method provided by an embodiment of the present application. The communication method is applied to the above-mentioned communication system and mainly involves the interaction between the terminal, the first session management network element, the second session management network element and the third session management network element.

[0143] As shown in FIG. 6, the flow of the communication method is as follows:

[0144] S601, the first session management network element receives the first message from the second session management network element.

[0145] The first session management network element is a session management network element that can obtain the subscription information of the terminal.

[0146] The first session management network element serves a first session of the terminal. The first session is a session established by the terminal according to a service requirement. The first session can be a PDU session or any other possible type of session, without limitation. The first session management network element serving the first session of the terminal can be understood as that the first session management network element can manage the first session. The first session management network element is configured to obtain the subscription information of the terminal.

[0147] The first message is configured to indicate, to the first session management network element, that the second session management network element serves the first session of the terminal (i.e., the first session is switched to be served by the second session management network element).

[0148] The second session management network element manages the first session, and the second session management network element supports local offloading.

[0149] Optionally, the first message can include indication information indicating that the second session management network element supports local offloading. For example, the indication information can include at least one of the following: an address of an edge application discovery network element (EASDF IP address), an address of a local domain name server (local DNS server address), an indication of EAS rediscovery (EAS rediscovery indication), an impact field indicating EAS rediscovery, and an offload identifier. When the first message includes at least one of these information, it can indicate that the second session management network element supports local offloading. These information elements are characteristic of a session management network element that supports local offloading. When serving a session as an intermediate session management network element, the session management network element sends the information to an anchor session management network element of the session. A session management network element that does not support local offloading does not send these information elements. Therefore, the present application does not limit that the second session management network element can only be indicated to support local offloading by the above information elements. Any information element that meets the above characteristics can be used to indicate that the second session management network element supports local offloading.

[0150] In a possible design, after the first session management network element receives the first message from the second session management network element, the method further includes: the first session management network element determines, according to the first message, that the second session management network element supports local offloading. In this way, the first session management network element can determine, according to the information included in the first message, whether the second session management network element supports local offloading. For example, when the first session management network element determines that the first message includes information indicating local offloading, it can be determined that the second session management network element supports local offloading.

[0151] It should be noted that the first message is a message sent by the second session management network element to the first session management network element after the terminal moves into the service range of the second session management network element. The first message is a message sent by the second session management network element based on whether the second session management network element supports local splitting (for example, whether the second session management network element has the function of configuring the edge application discovery network element). Therefore, after receiving the first message, the first session management network element can determine whether the second session management network element supports local splitting. Thus, the first session management network element can accurately determine whether the second session management network element supports local splitting according to the message sent by the second session management network element.

[0152] In a possible design, supporting local splitting includes: configuring an edge application discovery network element for the first session, and the edge application discovery network element is configured to select an address of a local edge application server (EAS) for the first session, and the address is used for local access of the first session.

[0153] It can be understood that the above-mentioned session management network element supporting local splitting can be understood as: the session management network element supports configuring an edge application discovery network element for the session of the terminal, so that the edge application discovery network element configured for the session of the terminal can select an address of an edge application server for the session of the terminal to support local access of the session. Alternatively, the session management network element supports configuring local access of the session of the terminal as an intermediate session management network element (I-SMF) of the session, for example, configuring a splitting point (ULCL, uplink classifier / BP, branching point) for the session of the terminal and selecting an edge application server.

[0154] For example, when the second session management network element supports local splitting, after the terminal moves into the service range of the second session management network element, the second session management network element can configure an edge application discovery network element (namely, an EASDF network element) for the session of the terminal, so that the configured edge application discovery network element can select an address of a local edge application server and send the address to the terminal to update the address of the domain name server configured in the terminal. Thus, the terminal can implement a session process through a server node corresponding to a location of the terminal, which can reduce the time delay of the service and improve the stability of the session.

[0155] Optionally, after the first session management network element receives the first message from the second session management network element, the method further comprises: in response to the first message, the first session management network element sends the address of the configured edge application discovery network element to the terminal. For example, the first session management network element receives the first message from the second session management network element when the terminal moves into the service range of the second session management network element before the terminal moves from the service range of the second session management network element to the service range of the third session management network element. The address of the configured edge application discovery network element is included in the first message.

[0156] It can be understood that when the second session management network element supports local offloading, the address of the configured edge application discovery network element is included in the first message sent to the first session management network element.

[0157] In this way, when the terminal is in the service range of the second session management network element, the address of the domain name server configured for the session of the terminal can be updated to the address of the local edge application server selected by the edge application discovery network element. Thus, the continuity of the session of the terminal is ensured by the address of the local edge application server, and the session interruption does not occur.

[0158] Optionally, after the first session management network element receives the first message from the second session management network element, the method further comprises: saving the first result, the first result indicating that the second session management network element supports local offloading; and the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message, comprising: the first session management network element sends the address of the domain name server to the terminal based on the first result and the second message.

[0159] It can be understood that after the first session management network element receives the first message from the second session management network element, the first session management network element can determine whether the second session management network element supports local offloading according to the first message, and save the determination result (for example, the first result). Thus, when determining whether to send the address of the domain name server to the terminal, the saved first result can be directly used for determination, and the efficiency of data information processing is improved without reanalyzing the first message.

[0160] In this way, when the terminal moves into the service range of a session management network element each time, the first session management network element can determine a result indicating whether the session management network element supports local offloading according to the message sent by the session management network element. When the terminal moves into the service range of another session management network element next time, the result can be directly used to determine whether the address of the domain name server needs to be sent to the terminal.

[0161] S602, the first session management network element receives a second message from the third session management network element.

[0162] The second message is used to indicate that the third session management network element serves the first session, and the third session management network element does not support local splitting. After the terminal moves from the service range of the second session management network element to the service range of the third session management network element, the terminal is located at the second location, that is, the service range of the third session management network element includes the second location of the terminal, that is, the second location is the location of the terminal after moving (from the service range of the second session management network element to the service range of the third session management network element).

[0163] It can be understood that the first location is the location of the terminal before moving, and the second location is the location of the terminal after moving. It can be considered that the terminal moves from the first location to the second location, that is, the terminal moves from the service range of the second session management network element to the service range of the third session management network element.

[0164] Similarly, after the first session management network element receives the second message from the third session management network element, the method can further include: saving a second result, the second result indicating that the third session management network element does not support local splitting. In this way, the first session management network element can determine to send the address of the domain name server to the terminal based on the first result and the second result.

[0165] Optionally, the service range of the second session management network element includes the first location of the terminal, or the service range of the third session management network element includes the second location of the terminal. It can be understood that the service range of the session management network element is one or more tracking areas (TA), and the location of the terminal belongs to one of the TAs, or the service range of the session management network element is one or more data network access identifiers (DNAI) (also referred to as DNAI supported by the session management network element), and the location of the terminal corresponds to at least one DNAI.

[0166] For example, the session management network element (the first session management network element, the second session management network element, or the third session management network element) can determine that the current location of the terminal can access at least one DNAI, or the current location of the terminal is close to at least one DNAI. Alternatively, the DNAI can be mapped to a TA, and the current location of the terminal is in one or more TAs mapped by the DNAI supported by the session management network element.

[0167] It should be noted that the first message sent by the second session management network element and the second message sent by the third session management network element can be different, and the proof message (the first message or the second message) can also be different in the way of indicating the first session of the terminal served by the session management network element. For example, the first message is an Nsmf_PDUSession_Create message, and the second message is an Nsmf_PDUSession_Update message. For example, when the message is a session update message (such as an Nsmf_PDUSession_Update message), the first session of the terminal served by the session management network element can be determined according to the session management context identifier (such as SM context ID) in the message; when the message is a session creation message (such as an Nsmf_PDUSession_Create message), the first session of the terminal served by the session management network element can be determined according to the session identifier (such as PDU session ID) in the message.

[0168] Optionally, the first session management network element can be an SMF or an anchor SMF of the first session, and the second session management network element and the third session management network element can be an I-SMF of the first session. The movement of the terminal can be reflected by the description of the network element, for example, according to the source I-SMF (source I-SMF) and the target I-SMF (target I-SMF) network element, it can be reflected that the terminal has moved, or according to the flow of the terminal switching flow, mobility registration update flow, etc. It can be reflected that the terminal has moved, etc. The present application does not limit this. For example, the second session management network element is a source I-SMF network element, and the third session management network element is a target I-SMF network element. The second session management network element is an SMF serving the UE before the UE moves, and the third session management network element is an SMF serving the UE after the UE moves.

[0169] In a possible design, after the first session management network element receives the second message from the third session management network element, the method further includes: the first session management network element determines that the third session management network element does not support local splitting according to the second message. In this way, the first session management network element can determine whether the third session management network element supports local splitting according to the information included in the second message. For example, when the first session management network element determines that the second message does not include related information indicating local splitting, it can be determined that the third session management network element does not support local splitting.

[0170] It should be noted that the second message is a message sent by the third session management network element to the first session management network element after the terminal moves into the service range of the third session management network element. The second message is a message sent by the third session management network element based on whether the third session management network element supports local offloading (for example, whether the third session management network element has the function of configuring the edge application discovery network element). Therefore, after receiving the second message, the first session management network element can determine whether the third session management network element supports local offloading. Thus, the first session management network element can accurately determine whether the third session management network element supports local offloading according to the message sent by the third session management network element.

[0171] For example, when the third session management network element does not support local offloading, the third session management network element cannot configure the edge application discovery network element for the session of the terminal after the terminal moves into the service range of the third session management network element. Therefore, the third session management network element does not include the indication information indicating that the third session management network element supports local offloading in the second message sent to the first session management network element. Thus, the first session management network element can determine that the third session management network element does not support local offloading when the second message does not include the indication information.

[0172] S603, the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message.

[0173] Optionally, the first message includes information indicating that the second session management network element supports local offloading, for example, any one or more of the following: the address of the local domain name server (local DNS server IP address), the address of the edge application discovery network element (EASDF IP address), indication information (EAS rediscovery indication) indicating that the terminal performs EAS rediscovery, a service (impact field) indicating that the terminal performs EAS rediscovery, and an offloading identifier.

[0174] When the information indicating that the third session management network element supports local splitting is not included in the second message, it can be considered that the third session management network element does not support local splitting. Correspondingly, when any one or more of the information elements satisfying the above characteristics are used to indicate that the second session management network element supports local splitting, the absence of the one or more information elements in the second message can indicate that the third session management network element does not support local splitting. Therefore, in this case, since the third session management network element does not support local splitting, the edge application discovery network element cannot be configured for the terminal, and at this time, since the second session management network element no longer serves the terminal, the address of the domain name server provided by the second session management network element for local access of the first session is no longer valid, and therefore the first session management network element needs to configure the address of the domain name server for the terminal to support local access of the first session. Therefore, the continuity of the session of the terminal is ensured without interruption.

[0175] The EAS rediscovery indication and impact field are used to indicate that the terminal clears / updates the locally stored DNS cache. The offload identifier is used by the I-SMF to indicate that the SMF stores the splitting information / policy (for example, local offloading information / policy) on the I-SMF, which is used to indicate that the I-SMF is allowed to perform local splitting of services.

[0176] In a possible design scheme, the address of the domain name server is a default domain name server address or a central domain name server address. Based on the default domain name server address or the central domain name server address, the terminal can maintain the continuity of the session at any location without interrupting the session.

[0177] Optionally, the address of the domain name server can also be another address, as long as the terminal can successfully resolve the service accessed by the terminal through the domain name server.

[0178] Optionally, the default domain name server address or the central domain name server address is an address locally stored by the first session management network element or an address obtained from a unified data repository (UDR) network element. The default domain name server address can be an address configured by a technician on the first session management network element.

[0179] Based on the above method, in the case that the terminal is located at the first location, the first session management network element serving the first session of the terminal and used to acquire the subscription information of the terminal can receive the first message of the second session management network element serving the first session of the terminal at the first location and supporting local offloading. In the case that the terminal moves from the first location to the second location, the first session management network element can also receive the second message of the third session management network element serving the first session of the terminal at the second location and not supporting local offloading. According to the first message and the second message, the address of the domain name server is sent to the terminal. In this way, when the location of the terminal changes and the intermediate session management network element serving the terminal switches, in the case that the switched intermediate session management network element does not support local offloading and cannot configure the edge application discovery network element for the session of the terminal, the first session management network element can allocate a new address of the domain name server for the terminal to provide services for the terminal, so as to ensure the continuity of the session of the terminal without interruption, thereby ensuring the user experience.

[0180] Optionally, the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message, including: in the case that the second session management network element supports local offloading and the third session management network element does not support local offloading, the first session management network element sends the address of the domain name server to the terminal. For example, the first session management network element can determine that the second session management network element supports local offloading according to the first message, and determine that the third session management network element does not support local offloading according to the second message. In this case, the first session management network element sends the address of the domain name server to the terminal, so as to ensure the continuity of the session of the terminal based on the address of the domain name server without interruption. In this way, when the first session management network element needs to configure the address of the domain name server for the terminal, the address of the domain name server is sent to the terminal, so as to avoid complex signaling process or sending multiple addresses to the terminal.

[0181] In a possible design scheme, when the second session management network element does not support local offloading and the third session management network element does not support local offloading, the first session management network element can also send the address of the domain name server to the terminal. In this case, the address of the domain name server sent by the first session management network element to the terminal is consistent with the address already configured in the terminal.

[0182] In a possible design scheme, the first session management network element, the second session management network element and the third session management network element belong to the same network. For example, the scenario of the present application is a non-roaming scenario of the terminal.

[0183] Optionally, before the first session management network element sends the address of the domain name server to the terminal, the method further comprises: the first session management network element obtaining authorization information of the terminal, the authorization information being used to indicate that the session of the terminal is allowed to be locally split; and the first session management network element sending the address of the domain name server to the terminal according to the first message and the second message, comprising: based on the authorization information, the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message.

[0184] It can be understood that the authorization information of the terminal is included in the context of the first session when the first session of the terminal is established. Therefore, before the first session management network element sends the address of the domain name server to the terminal, the first session management network element can further judge the authorization information of the terminal, so that the address of the domain name server is sent to the terminal only when the authorization information of the terminal indicates that the session of the terminal is allowed to be locally split. If the authorization information of the terminal indicates that the session of the terminal is not allowed to be locally split, the address of the domain name server will not be sent to the terminal. Therefore, the accuracy of sending the address of the domain name server to the terminal is further ensured, and the situation of sending multiple addresses of domain name servers to the terminal is avoided.

[0185] Implementation manner one

[0186] In a possible design, the first message includes the address of the edge application discovery network element configured by the second session management network element for the first session, and the second message does not include the address of the edge application discovery network element.

[0187] In a possible design, the first session management network element sends the address of the domain name server to the terminal according to the first message and the second message, comprising: the first session management network element sends the address of the domain name server to the terminal according to that the first message includes the address of the edge application discovery network element configured by the second session management network element for the first session and the second message does not include the address of the edge application discovery network element. In this way, the address of the domain name server can be sent to the terminal only when the session management network element corresponding to the location where the terminal moves after the terminal moves does not send the address of the edge application discovery network element to the first session management network element. This ensures that the address of the usable domain name server is configured in the terminal, and avoids the interruption of the session of the terminal.

[0188] It can be understood that when the first message includes the address of the edge application discovery network element configured by the second session management network element for the first session, it indicates that the second session management network element supports local splitting, and when the second message does not include the address of the edge application discovery network element, it indicates that the third session management network element does not support local splitting. At this time, the first session management network element can send the address of the domain name server to the terminal. In this way, when the third session management network element cannot configure the edge application discovery network element for the first session of the terminal, the first session management network element can configure the address of the domain name server for the terminal.

[0189] As shown in FIG. 7, an exemplary flowchart for updating the address of the domain name server for the terminal is shown.

[0190] S701, a session is established.

[0191] When the terminal accesses the network, a session is established for the terminal, and the session is a session supporting local offloading.

[0192] Optionally, in the process of establishing the session, the AMF network element also indicates in the subscription / policy obtained that the AMF network element falls back to the ETSUN step instead of releasing the session when an I-SMF network element supporting R19 cannot be selected.

[0193] S702, the terminal moves.

[0194] When the terminal accesses the network, the I-SMF network element providing service for the terminal is switched as the terminal moves. For example, the terminal moves from the service range of the I-SMF1 network element to the service range of another I-SMF2 network element. Both of the two I-SMF network elements are SMF network elements supporting local offloading (supporting R19).

[0195] S703, the AMF network element sends an establish session context message to the I-SMF2 network element. Correspondingly, the I-SMF2 network element receives the establish session context message sent by the AMF network element.

[0196] Specifically, the establish session context message can be Nsmf_PDUSession_CreateSMContext Request.

[0197] Optionally, the AMF network element can also send a local offloading allowed indication message to the I-SMF2 network element.

[0198] S704, the I-SMF2 network element sends a provide session context message to the I-SMF1 network element. Correspondingly, the I-SMF1 network element receives the provide session context message sent by the I-SMF2 network element.

[0199] Specifically, the provide session context message can be Nsmf_PDUSession_Context Request.

[0200] Optionally, the I-SMF2 network element can also send a local offloading supported inidcation message to the I-SMF1 network element.

[0201] S705, the I-SMF1 network element places the authorization result in the context.

[0202] The I-SMF1 network element can place the authorization result (authorization result) in the context (SM Context).

[0203] S706, the I-SMF1 network element sends a response message to the I-SMF2 network element. Correspondingly, the I-SMF2 network element receives the response message sent by the I-SMF1 network element.

[0204] The response message can be Nsmf_PDUSession_Context Response. The response message can also include an authorization result (authorization result for local offloading) indicating support for local offloading.

[0205] For example, when obtaining the context, if the I-SMF2 network element indicates to the I-SMF1 network element that it supports local offloading, the I-SMF1 network element will send the authorization result to the I-SMF2 network element.

[0206] S707, the I-SMF2 network element selects the V-EASDF network element to determine the local edge application server.

[0207] The I-SMF2 network element can select the corresponding V-EASDF network element according to the authorization result for local offloading included in the received response message, and determine the local edge application server through the V-EASDF network element.

[0208] S708, the I-SMF2 network element sends a session update message to the SMF network element. Correspondingly, the SMF network element receives the session update message sent by the I-SMF2 network element.

[0209] The session update message can be Nsmf_PDUSession_Update Request message, and the information indicating support of local offloading in the message can include at least one of the following: an address of the EASDF network element (EASDF address), an address of a local domain name server (local DNS server address), information indicating clearing of a DNS cache (EAS rediscovery indication), and an identifier of a policy (offload ID). The information indicating support of local offloading can be information capable of indicating that the target I-SMF network element supports local offloading / local EAS discovery.

[0210] In S709, the SMF network element stores the information indicating support of local offloading.

[0211] The SMF network element can store the information (EASDF address, local DNS server address, EAS rediscovery indication, and offload ID) included in the session update message locally.

[0212] In S710, the SMF network element sends a session update response message to the terminal. Correspondingly, the terminal receives the session update response message sent by the SMF network element.

[0213] The session update response message can be Nsmf_PDUSession_Update Response message, and the information indicating support of local offloading in the session update response message.

[0214] The SMF network element can send the stored information (EASDF address, local DNS server address, EAS rediscovery indication, and offload ID) indicating support of local offloading to the terminal through the Nsmf_PDUSession_Update Response message.

[0215] It can be understood that when the terminal moves within the service range of two I-SMF network elements supporting R19, the target I-SMF network element (namely, the I-SMF network element 2) performs reselection of an EASDF network element and the like, and sends information such as an address of the EASDF network element to the SMF network element. At this time, the SMF network element performs corresponding actions, for example, configures the default DNS server of the terminal to be the address of the EASDF network element according to the address of the EASDF network element indicated by the target I-SMF network element.

[0216] S711, the terminal moves.

[0217] The terminal moves from the service scope of the I-SMF 2 network element to the service scope of another I-SMF 3 network element. The I-SMF 2 network element is an SMF network element supporting local offloading (supporting R19), and the I-SMF 3 network element is an SMF network element not supporting local offloading (supporting R19).

[0218] S712, the AMF network element sends an establish session context message to the I-SMF 3 network element. Correspondingly, the I-SMF 3 network element receives the establish session context message sent by the AMF network element.

[0219] Specifically, the establish session context message can be Nsmf_PDUSession_CreateSMContext Request.

[0220] S713, the I-SMF 3 network element sends a provide session context message to the I-SMF 2 network element. Correspondingly, the I-SMF 2 network element receives the provide session context message sent by the I-SMF 3 network element.

[0221] Specifically, the provide session context message can be Nsmf_PDUSession_Context Request. The provide session context message does not include a local offloading support indication (specifically, local offloading supported indication).

[0222] S714, the I-SMF 2 network element determines that the I-SMF 3 network element does not support local offloading.

[0223] The I-SMF 2 network element can determine that the authorization result is not included in the context (SM Context) according to the fact that the local offloading support indication (specifically, local offloading supported indication) is not indicated in the Nsmf_PDUSession_Context Request message.

[0224] S715, the I-SMF 2 network element sends a response message to the I-SMF 3 network element. Correspondingly, the I-SMF 3 network element receives the response message sent by the I-SMF 2 network element.

[0225] The response message can be Nsmf_PDUSession_Context Response. The response message does not include the authorization result for local offloading.

[0226] S716, the I-SMF3 network element sends a session update message to the SMF network element. Correspondingly, the SMF network element receives the session update message sent by the I-SMF3 network element.

[0227] The session update message can be Nsmf_PDUSession_Update Request message, and the message does not include information indicating support of local splitting.

[0228] S717, the SMF network element determines that the session update message does not include information indicating support of local splitting.

[0229] The SMF network element determines that the Nsmf_PDUSession_Update Request message does not include information such as EASDF address, local DNS server address, EAS rediscovery indication, offload ID, and determines that the I-SMF2 network element supports local splitting.

[0230] S718, it is determined that the session is a session supporting local splitting.

[0231] Optionally, the SMF network element can also determine that the session has been authorized for local offloading, and then send the address of the default domain name server (default DNS server address) to the terminal.

[0232] S719, the SMF network element sends a session update response message to the terminal. Correspondingly, the terminal receives the session update response message sent by the SMF network element.

[0233] The session update response message can be Nsmf_PDUSession_Update Response message, and the session update response message includes the address of the default domain name server (default DNS server address). The address of the default domain name server can be a default address configured on the SMF network element, which is directly sent when it needs to be sent to the terminal.

[0234] Optionally, the session update response message can also include information indicating clearing of the DNS cache (EAS rediscovery indication), or Interest DNAI.

[0235] It should be noted that in the process of the terminal updating the address of the domain name server, S702, S704, S705 and S706 can not be executed (i.e., the case of terminal movement in S702 can not exist), in which case, based on the three steps of S701, S703 and S707, the process of the session establishment (response) message can be completed through S708 and S710 (may also include S709).

[0236] Implementation mode two:

[0237] In a possible design, the first message includes information of a first area, and the first area is an area supported by the second session management network element; and the second message includes information of a second area, and the second area is an area supported by the third session management network element. In this way, by determining the areas supported by the session management network elements and in combination with the service area subscribed by the terminal, it can be determined whether the session management network element corresponding to the location of the terminal supports updating the address of the domain name server configured in the terminal. It is thus determined whether to configure the address of the domain name server for the terminal. This is to ensure that the terminal is configured with a usable address of the domain name server, and to avoid the case that the session of the terminal is interrupted.

[0238] It should be noted that the area supported by the session management network element can be understood as one or more supported DNAI (supported DNAI(s)) or a service area of the session management network element.

[0239] In a possible design, the first session management network element determines, according to the first message, that the second session management network element supports local splitting, including: the first session management network element determines, according to the first message, that the first area overlaps with a third area, and determines that the second session management network element supports local splitting, and the third area is a service area subscribed by the terminal.

[0240] In a possible design, the method further includes: the first session management network element obtains information of a third area from a data management network element. For example, the information of the service area subscribed by the terminal can be obtained from a unified data management (UDM) network element serving the terminal (the first session of the terminal).

[0241] It should be noted that the first region overlaps with the third region can be considered that the third region includes part or all of the first region, for example, the third region includes the complete first region, or the third region includes part of the first region. For example, the first region includes A region, B region and C region, and the second region includes A region and B region, the first region overlaps with the third region, and the third region includes all of the first region; or, the first region includes A region, B region and C region, and the second region includes A region, the first region overlaps with the third region, and the third region includes part of the first region.

[0242] In a possible design, the first session management network element determines, according to the second message, that the third session management network element does not support local offloading, including: the first session management network element determines, according to the second message, that the second region does not overlap with the third region, and determines that the third session management network element does not support local offloading, the third region being a service region of the terminal.

[0243] Similarly, the second region does not overlap with the third region can be considered that the third region does not include any part of the second region. For example, the first region includes A region, B region and C region, and the second region includes D region and E region, the second region does not overlap with the third region, and the third region does not include any part of the second region.

[0244] In a possible design, the first session management network element sends, according to the first message and the second message, an address of a domain name server to the terminal, including: the first session management network element sends, according to that the first region overlaps with the third region and the second region does not overlap with the third region, an address of a domain name server to the terminal, the third region being a service region of the terminal.

[0245] It can be understood that the first region overlaps with the third region can indicate that the second session management network element supports local offloading, and the second region does not overlap with the third region indicates that the third session management network element does not support local offloading. In this case, the third session management network element cannot configure an edge application discovery network element for the first session of the terminal, and needs to configure an address of a domain name server for the terminal through the first session management network element.

[0246] For example, as shown in FIG. 8, a flowchart for updating an address of a domain name server for a terminal is shown.

[0247] S801, a session is established.

[0248] When the terminal accesses a network, a session is established for the terminal, and the session is a session supporting local offloading.

[0249] Optionally, in the process of establishing the session, the SMF network element also needs to configure the service area of the terminal subscription, that is, configure the network access identification list (DNAI list) supported by the terminal for local offloading. That is, the network access identification list (DNAI list) is used to indicate the service area of the terminal subscription (i.e. the third area described above). The network access identification list supported by the terminal for local offloading can be obtained from the UDM network element as subscription information.

[0250] Optionally, in the process of establishing the session, the AMF network element is also indicated in the subscription / policy obtained by the AMF network element to fall back to the ETSUN step instead of releasing the session when an I-SMF network element supporting R19 cannot be selected.

[0251] S802, the terminal moves.

[0252] When the terminal accesses the network, the I-SMF network element providing service to the terminal is switched as the terminal moves. That is, the terminal moves from the service range of the I-SMF1 network element to the service range of another I-SMF2 network element. Both of the two I-SMF network elements are SMF network elements supporting local offloading (supporting R19).

[0253] S803, the AMF network element sends a session context establishment message to the I-SMF2 network element. Correspondingly, the I-SMF2 network element receives the session context establishment message sent by the AMF network element.

[0254] Specifically, the session context establishment message can be Nsmf_PDUSession_CreateSMContext Request.

[0255] Optionally, the AMF network element can also send a local offloading allowed message (specifically, local offloading allowed indication) to the I-SMF2 network element.

[0256] S804, the I-SMF2 network element sends a session context provision message to the I-SMF1 network element. Correspondingly, the I-SMF1 network element receives the session context provision message sent by the I-SMF2 network element.

[0257] Specifically, the session context provision message can be Nsmf_PDUSession_Context Request.

[0258] Optionally, the I-SMF2 network element can also send a local offloading supported message (specifically, local offloading supported inidcation) to the I-SMF1 network element.

[0259] S805. The I-SMF1 network element places the authorization result in the context.

[0260] The I-SMF1 network element can place the authorization result (authorization result) in the context (SM Context).

[0261] S806. The I-SMF1 network element sends a response message to the I-SMF2 network element. Correspondingly, the I-SMF2 network element receives the response message sent by the I-SMF1 network element.

[0262] The response message can be Nsmf_PDUSession_Context Response. The response message can also include the authorization result for local offloading (authorization result for local offloading).

[0263] For example, when obtaining the context, if the I-SMF2 network element indicates to the I-SMF1 network element that local offloading is supported, the I-SMF1 network element will send the authorization result to the I-SMF2 network element.

[0264] S807. The I-SMF2 network element selects a V-EASDF network element to determine a local edge application server.

[0265] The I-SMF2 network element can select a corresponding V-EASDF network element according to the authorization result for local offloading included in the received response message, and determine a local edge application server through the V-EASDF network element.

[0266] S808. The I-SMF2 network element sends a session update message to the SMF network element. Correspondingly, the SMF network element receives the session update message sent by the I-SMF2 network element.

[0267] The session update message can be Nsmf_PDUSession_Update Request message, and the message can include information indicating support of local offloading and a network access identifier list supported by the I-SMF2 network element (I-SMF2 supported DNAI list). The information indicating support of local offloading can be at least one of an address of the EASDF network element (EASDF address), an address of a local domain name server (local DNS server address), information indicating clearing of a DNS cache (EAS rediscovery indication), and an identifier of a policy (offload ID).

[0268] It should be noted that as the terminal moves, each time it moves into the service range of a new I-SMF network element, the new I-SMF network element reports the supported network access identifier list to the SMF network element.

[0269] S809, the SMF network element stores the first result.

[0270] The SMF network element can determine, according to the session update message, that there is an overlapping area between the network access identifier list supported by the terminal for local offloading and the network access identifier list supported by the I-SMF2 network element, and then determine that the I-SMF2 network element supports local offloading and store the determination as the first result.

[0271] Optionally, the I-SMF2 network element supports local offloading is determined only when the network access identifier list supported by the terminal for local offloading is completely consistent with (i.e., completely overlaps) the network access identifier list supported by the I-SMF2 network element.

[0272] S810, the SMF network element sends a session update response message to the terminal. Correspondingly, the terminal receives the session update response message sent by the SMF network element.

[0273] The session update response message can be Nsmf_PDUSession_Update Response message, and the session update response message includes information indicating support of local offloading.

[0274] The SMF network element can send the stored information indicating support of local offloading (EASDF address, local DNS server address, EAS rediscovery indication, and offload ID) to the terminal through the Nsmf_PDUSession_Update Response message.

[0275] It can be understood that when the terminal moves in the service range of two I-SMF network elements supporting R19, the target I-SMF network element (namely, I-SMF network element 2) performs reselection of the EASDF network element and the like, and sends the address of the EASDF network element and the like to the SMF network element. At this time, the SMF network element performs corresponding actions, for example, according to the address of the EASDF network element indicated by the target I-SMF network element, the default DNS server of the terminal is configured as the address of the EASDF network element.

[0276] S811, the terminal moves.

[0277] The terminal moves from the service range of the I-SMF2 network element to the service range of another I-SMF3 network element. The I-SMF2 network element is an SMF network element supporting local offloading (supporting R19), and the I-SMF3 network element is an SMF network element not supporting local offloading (supporting R19).

[0278] S812, the AMF network element sends a create session context message to the I-SMF3 network element. Correspondingly, the I-SMF3 network element receives the create session context message sent by the AMF network element.

[0279] Specifically, the create session context message can be Nsmf_PDUSession_CreateSMContext Request.

[0280] S813, the I-SMF3 network element sends a provide session context message to the I-SMF2 network element. Correspondingly, the I-SMF2 network element receives the provide session context message sent by the I-SMF3 network element.

[0281] Specifically, the provide session context message can be Nsmf_PDUSession_Context Request. The provide session context message does not include a local offloading supported indication (specifically, a local offloading supported indication).

[0282] S814, the I-SMF2 network element determines that the I-SMF3 network element does not support local offloading.

[0283] The I-SMF2 network element can determine that the authorization result is not included in the context (SM Context) according to the fact that the local offloading supported indication is not indicated in the Nsmf_PDUSession_Context Request message.

[0284] S815, the I-SMF2 network element sends a response message to the I-SMF3 network element. Correspondingly, the I-SMF3 network element receives the response message sent by the I-SMF2 network element.

[0285] The response message can be Nsmf_PDUSession_Context Response. The response message does not include an authorization result for local offloading.

[0286] S816, the I-SMF3 network element sends a session update message to the SMF network element. Correspondingly, the SMF network element receives the session update message sent by the I-SMF3 network element.

[0287] The session update message can be Nsmf_PDUSession_Update Request, which includes an I-SMF2 supported DNAI list supported by the I-SMF3 network element.

[0288] S817, the SMF network element determines that the I-SMF3 network element does not support local offloading and the I-SMF2 network element supports local offloading.

[0289] The SMF network element determines that the I-SMF3 network element does not support local offloading according to the session update message, and determines that the I-SMF2 network element supports local offloading according to the first result.

[0290] S818, it is determined that the session is a local offloading supported session.

[0291] Optionally, the SMF network element can also determine that the session has been authorized for local offloading, and then send a default DNS server address to the terminal.

[0292] S819, the SMF network element sends a session update response message to the terminal. Correspondingly, the terminal receives the session update response message sent by the SMF network element.

[0293] The session update response message can be an Nsmf_PDUSession_Update Response message, and the session update response message includes a default DNS server address. The default DNS server address can be a default address configured on the SMF, and the address is directly sent to the terminal when the address needs to be sent to the terminal.

[0294] Optionally, the session update response message can further include information (EAS rediscovery indication) indicating clearing of a DNS cache, or an Interest DNAI.

[0295] It should be noted that in the process of updating the address of the domain name server by the terminal, S802, S804, S805, and S806 can not be executed (that is, the case of terminal movement in S802 can not exist), and in this case, the process of the session establishment (response) message can be completed through S808 and S810 (and S809 can also be included) based on the three steps of S801, S803, and S807.

[0296] The communication method provided in the embodiments of the present application is described in detail above in combination with FIGS. 6-8. The communication apparatus for executing the communication method provided in the embodiments of the present application is described in detail below in combination with FIGS. 9-10.

[0297] FIG. 9 is a structural schematic diagram of a communication apparatus provided in an embodiment of the present application. As shown in FIG. 9, the communication apparatus 900 includes a transceiver module 901 and a processing module 902. For ease of description, FIG. 9 only shows the main components of the communication apparatus.

[0298] The transceiver module 901 is configured to perform the transceiving functions of the methods shown in FIGS. 6-8, and the processing module 902 is configured to perform other functions of the methods shown in FIGS. 6-8 other than the transceiving functions.

[0299] Optionally, the transceiver module 901 can include a sending module (not shown in FIG. 9) and a receiving module (not shown in FIG. 9). The sending module is configured to implement the sending function of the communication apparatus 900, and the receiving module is configured to implement the receiving function of the communication apparatus 900.

[0300] Optionally, the communication apparatus 900 can further include a storage module (not shown in FIG. 9), which stores a program or instructions. When the processing module 902 executes the program or instructions, the communication apparatus 900 can perform the functions of the respective devices / network elements in the methods shown in FIGS. 6-8 in the above methods.

[0301] It can be understood that the communication apparatus 900 can be a network device, a chip (system) or other components or assemblies which can be arranged in the network device, or an apparatus including the network device, and the present application does not limit the same.

[0302] In addition, the technical effects of the communication apparatus 900 can refer to the technical effects of the communication methods shown in FIGS. 6-8, which are not described herein.

[0303] FIG. 10 is a structural schematic diagram of a communication apparatus according to an embodiment of the present application. The communication apparatus can be a terminal, or a chip (system) or other components or assemblies which can be arranged in the terminal. As shown in FIG. 10, the communication apparatus 1000 can include a processor 1001. Optionally, the communication apparatus 1000 can further include a memory 1002 and / or a transceiver 1003. The processor 1001 is coupled with the memory 1002 and the transceiver 1003, for example, through a communication bus.

[0304] The various constituent components of the communication apparatus 1000 will be specifically introduced below in combination with FIG. 10.

[0305] The processor 1001 is the control center of the communication apparatus 1000, which can be one processor or a collective term of multiple processing elements. For example, the processor 1001 is one or more central processing units (CPUs), application specific integrated circuits (ASICs), or one or more integrated circuits configured to implement one or more embodiments of the present application, such as one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs).

[0306] Optionally, the processor 1001 can perform various functions of the communication apparatus 1000 by running or executing software programs stored in the memory 1002 and calling data stored in the memory 1002, such as the communication methods shown in FIGS. 6-8.

[0307] In a specific implementation, as an embodiment, the processor 1001 can include one or more CPUs, such as the CPU0 and the CPU1 shown in FIG. 10.

[0308] In a specific implementation, as an example, the communication apparatus 1000 can also include multiple processors, such as the processor 1001 and the processor 1004 shown in FIG. 10. Each of the processors can be a single-CPU or a multi-CPU. The processor herein can refer to one or more devices, circuits, and / or processing cores for processing data (for example, computer program instructions).

[0309] The memory 1002 is configured to store a software program for implementing the solutions of the present application, and the processor 1001 is configured to control the execution of the software program. The specific implementation manners can refer to the above-mentioned method embodiments, and will not be described here.

[0310] Optionally, the memory 1002 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, and can also be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including a compact disc, a laser disc, an optical disc, a digital versatile disc, a Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium capable of carrying or storing desired program codes in the form of instructions or data structures and capable of being accessed by a computer, but is not limited to this. The memory 1002 can be integrated with the processor 1001 or exist independently and be coupled with the processor 1001 through an interface circuit (not shown in FIG. 10) of the communication apparatus 1000, and the embodiments of the present application are not limited in this regard.

[0311] The transceiver 1003 is configured to communicate with other communication apparatuses. For example, the communication apparatus 1000 is a terminal, and the transceiver 1003 can be configured to communicate with a network device or another terminal. For another example, the communication apparatus 1000 is a network device, and the transceiver 1003 can be configured to communicate with a terminal or another network device.

[0312] Optionally, the transceiver 1003 can include a receiver and a transmitter (not shown separately in FIG. 10). The receiver is configured to implement the receiving function, and the transmitter is configured to implement the transmitting function.

[0313] Optionally, the transceiver 1003 can be integrated with the processor 1001, or exist independently, and be coupled with the processor 1001 through an interface circuit (not shown in FIG. 10) of the communication apparatus 1000, and embodiments of the present application do not make a limitation in this regard.

[0314] It can be understood that the structure of the communication apparatus 1000 shown in FIG. 10 does not constitute a limitation on the communication apparatus, and an actual communication apparatus can include more or fewer components than those shown, or combine certain components, or have a different arrangement of components.

[0315] In addition, the technical effects of the communication apparatus 1000 can refer to the technical effects of the methods described in the above method embodiments, which will not be described herein again.

[0316] It should be understood that the processor in the embodiments of the present application can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0317] It should also be understood that the memory in the embodiments of the present application can be a volatile memory or a nonvolatile memory, or can include both volatile and nonvolatile memory. Among them, the nonvolatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example, and not limitation, many forms of random access memory (RAM) are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0318] The above-described embodiments can be implemented in part or in whole through software, hardware (e.g., circuitry), firmware, or any combination thereof. When implemented in software, the above-described embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When loaded and executed by a computer, the computer instructions or computer programs can produce the processes or functions described above in accordance with the embodiments of the present application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, such as from a website site, a computer, a server, or a data center to another website site, a computer, a server, or a data center through a wired (e.g., infrared, wireless, microwave, etc.) manner. The computer-readable storage medium can be any available medium or a collection of medium accessible by a computer or a data storage device such as a server, a data center, etc. containing one or more available medium. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state disk.

[0319] It should be understood that the term "and / or" in this document is merely used to describe an associated relationship between associated objects, and can represent three relationships, for example, A and / or B can represent three cases of A alone, A and B together, and B alone, where A and B can be singular or plural. In addition, the character " / " in this document generally represents an "or" relationship between the front and rear associated objects, but can also represent an "and / or" relationship. The specific meaning can be understood according to the context before and after.

[0320] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions means any combination of the items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0321] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-described processes does not mean the order of execution, and the execution order of the processes should be determined according to their functions and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0322] Those skilled in the art can clearly understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0323] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0324] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0325] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0326] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit.

[0327] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0328] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A communication method characterized by comprising: The method comprises: The first session management network element receives a first message from a second session management network element, the first message being used to indicate that the second session management network element serves a first session of a terminal, the first session management network element serving the first session, the first session management network element being configured to acquire subscription information of the terminal, the second session management network element supporting local breakout, a service range of the second session management network element including a first location of the terminal, the first location being a location before the terminal moves; The first session management network element receives a second message from a third session management network element, the second message being used to indicate that the third session management network element serves the first session, the third session management network element not supporting local breakout, a service range of the third session management network element including a second location of the terminal, the second location being a location after the terminal moves; The first session management network element sends an address of a domain name server to the terminal according to the first message and the second message.

2. The method of claim 1, wherein, The method further comprises: The first session management network element determines, according to the first message, that the second session management network element supports local breakout; The first session management network element determines, according to the second message, that the third session management network element does not support local breakout.

3. The method of claim 2, wherein, The first session management network element sends an address of a domain name server to the terminal according to the first message and the second message, comprising: In a case where the second session management network element supports local breakout and the third session management network element does not support local breakout, the first session management network element sends the address of the domain name server to the terminal.

4. The method of claim 1, wherein, The support for local breakout comprises: configuring an edge application discovery network element for the first session, the edge application discovery network element being configured to select an address of an edge application server for the first session, the address being used for local access of the first session.

5. The method according to any one of claims 1-4, characterized in that, The first message comprises an address of an edge application discovery network element configured by the second session management network element for the first session, and the second message does not comprise an address of an edge application discovery network element.

6. The method of claim 5, wherein, The first session management network element sends an address of a domain name server to the terminal according to the first message and the second message, comprising: The first session management network element sends the address of the domain name server to the terminal according to the first message comprising the address of the edge application discovery network element configured by the second session management network element for the first session and the second message not comprising an address of an edge application discovery network element.

7. The method according to any one of claims 1 to 6, characterized in that, The first session management network element, the second session management network element and the third session management network element belong to the same network.

8. The method of claim 2, wherein, The first message comprises information of a first area, the first area being an area supported by the second session management network element, and the second message comprises information of a second area, the second area being an area supported by the third session management network element.

9. The method of claim 8, wherein, The first session management network element determines, according to the first message, that the second session management network element supports local breakout, comprising: The first session management network element determines, according to the first message, that the first area overlaps with a third area, and determines that the second session management network element supports local splitting, the third area being a service area to which the terminal is subscribed.

10. The method of claim 8, wherein, The first session management network element determines, according to the second message, that the third session management network element does not support local splitting, including: The first session management network element determines, according to the second message, that the second area does not overlap with a third area, and determines that the third session management network element does not support local splitting, the third area being a service area to which the terminal is subscribed.

11. The method according to any one of claims 8-10, characterized in that, The first session management network element sends, according to the first message and the second message, an address of a domain name server to the terminal, including: The first session management network element sends, according to that the first area overlaps with a third area and the second area does not overlap with the third area, the address of the domain name server to the terminal, the third area being a service area to which the terminal is subscribed.

12. The method according to any one of claims 9-11, characterized in that, The method further includes: The first session management network element obtains information of the third area from a data management network element.

13. The method according to any one of claims 1-12, characterized in that, The address of the domain name server is an address of a default domain name server or an address of a central domain name server.

14. The method of any one of claims 1-13, wherein, The method further includes: The first session management network element obtains authorization information of the terminal, the authorization information being used to indicate that local splitting is allowed for a session of the terminal; The first session management network element sends, according to the first message and the second message, the address of the domain name server to the terminal, including: Based on the authorization information, the first session management network element sends, according to the first message and the second message, the address of the domain name server to the terminal.

15. The method of any one of claims 1-14, wherein, The method further includes, after the first session management network element receives the first message from the second session management network element: Saving a first result, the first result indicating that the second session management network element supports local splitting; The first session management network element sends, according to the first message and the second message, the address of the domain name server to the terminal, including: The first session management network element sends, based on the first result and the second message, the address of the domain name server to the terminal.

16. A method of communication, comprising: The method applied to a third session management network element includes: In a case where a terminal moves from a first location to a second location, the third session management network element sends a second message to a first session management network element, the first location being a location in a service range of a second session management network element, the second location being a location in a service range of the third session management network element, the second message being used to indicate that the third session management network element services a first session of the terminal, the second session management network element services the first session of the terminal, the second session management network element supports local splitting, the third session management network element does not support local splitting, the first session management network element services the first session, and the first session management network element is used to obtain subscription information of the terminal; The third session management network element receives an address of a domain name server from the first session management network element, and sends the address of the domain name server to the terminal.

17. A communications device, characterized by The apparatus includes means for performing the method of any of claims 1-16.

18. A communications device, characterized by The communication apparatus includes a processor and a memory; the memory is configured to store computer instructions, when the processor executes the instructions, to cause the communication apparatus to perform the method of any of claims 1-16.

19. A computer-readable storage medium, characterized in that, The computer readable storage medium includes a computer program or instructions, when the computer program or instructions are run on a computer, to cause the computer to perform the method of any of claims 1-16.

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