Method and device of communication

Description

1 / 67 METHOD AND APPARATUS OF COMMUNICATION CROSS-REFERENCE TO RELATED REQUESTS

[0001] This application claims priority over Chinese Patent Application No. 202310303879.6, filed with the National Intellectual Property Administration of China on March 20, 2023, and entitled COMMUNICATION METHOD AND APPARATUS, which is incorporated herein by reference in its entirety. This application claims priority over Chinese Patent Application No. 202310566365.X, filed with the National Intellectual Property Administration of China on May 18, 2023, and entitled COMMUNICATION METHOD AND APPARATUS, which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The modalities of this application relate to the field of communication technologies and, in particular, to a method and apparatus of communication. BACKGROUND

[0003] Currently, communication systems such as 4th generation (4G) and 5th generation (5G) communication systems support a user plane function (UPF) network element that acts as an uplink classifier (ULCL) to direct a user's packets to different session anchors (e.g., packet data unit (PDU) session anchors), allowing the user to access different data networks simultaneously. For example, the user can access both a dedicated data network of a company or similar and a public data network, such as the internet.

[0004] However, a traffic routing rule for a packet to the dedicated data network is usually preconfigured or defined in a session management function (SMF) network element or a Petition 870250099131, dated 10 / 29 / 2025, page 8 / 86 2 / 67 UPF network element in a dedicated data network location. In this case, there is a problem: the user cannot continue accessing the dedicated data network after leaving the dedicated data network location. SUMMARY

[0005] The embodiments of this application provide a method and a communication device for creating a session through an SMF network element at a visited location (or roaming location) based on an identifier of a dedicated data network, so that a terminal device user can access both a public data network and the dedicated data network. Furthermore, traffic from the public data network is offloaded at the visited location (or roaming location) to avoid traffic looping.

[0006] According to a first aspect, an embodiment of this request provides a method of communication. The method includes: a first session management network element receives the first information from a policy control network element, wherein the first information includes an identifier of a first dedicated data network to which a terminal device subscribes, and the first session management network element is a session management network element at a visited location of the terminal device; the first session management network element sends a first request to a second session management network element, wherein the first request includes the identifier of the first dedicated data network, and the second session management network element is a session management network element that supports the first dedicated data network;The first session management network element receives a first response from the second session management network element, where the first response includes second tunnel information from a second element; Petition 870250099131, dated 10 / 29 / 2025, page 9 / 86 3 / 67 user plane function network, and the second user plane function network element is a user plane function network element selected by the second session management network element based on the first dedicated data network; and the first session management network element sends second information to a first user plane function network element, wherein the second information includes second tunnel information and a first traffic routing rule, the first traffic routing rule indicates that the first user plane function network element should send, to the second user plane function network element, a packet destined for the first dedicated data network and sent by the terminal device,The first user-plane function network element is a user-plane function network element selected for a general data network to which the terminal device subscribes. Optionally, the method also includes: the first session management network element obtains, through a network repository function network element, information about the second session management network element that supports the first dedicated data network.

[0007] According to the method above, in a scenario such as a terminal device user roaming between provinces / cities, a session management network element at a roaming location (or a visited location) can create a session based on a dedicated data network identifier, so that the terminal device user can access both a public data network and the dedicated data network. Furthermore, traffic from the public data network can still be sent by a user plane function network element at the visited location to the public data network and is offloaded at the roaming location (i.e., the visited location), to avoid the Petition 870250099131, dated 10 / 29 / 2025, page 10 / 86 4 / 67 traffic loop.

[0008] In a possible project, the initial information also includes a list of internet protocol (IP) addresses and / or a list of domain names that correspond to the first dedicated data network; and the first traffic routing rule includes the list of IP addresses and / or the list of domain names.

[0009] According to the previous project, a dynamic traffic routing rule and similar rules delivered by the policy control function network element can be extended to carry information such as a domain name corresponding to a dedicated data network, so that the user plane function network element can route a packet (or traffic) based on the domain name. Furthermore, a predefined traffic routing rule from a source location is not configured on the session management network element at the roaming location (or visited location).

[0010] In a possible project, the first request also includes the first tunnel information from the first user plane function network element.

[0011] The previous design helps establish a downlink tunnel from the second selected user plane function network element to the first dedicated data network and facilitates the transmission of a downlink packet from the first dedicated data network to the terminal device.

[0012] In one possible project, the first request also includes an IP address of the terminal device.

[0013] The previous project helps the second selected user plane function network element for the first dedicated data network to learn the terminal device's IP address and associate the terminal device's IP address with an address Petition 870250099131, dated 10 / 29 / 2025, page 11 / 86 5 / 67 The terminal device's dedicated IP address on the primary dedicated data network is used to perform address translation on a packet transmitted between the primary dedicated data network and the terminal device.

[0014] In a possible design, the method also includes: When the terminal device is located in a service area of ​​the second user plane function network element, the first session management network element sends fourth information to the second user plane function network element, wherein the fourth information includes the first tunnel information from the first user plane function network element and a second traffic routing rule, and the second traffic routing rule instructs the second user plane function network element to send, to the first user plane function network element, a packet that is not for the first dedicated data network and that is sent by the terminal device.Before the first session management network element sends the second piece of information to the first user plane role network element, the method also includes: The first session management network element determines that the endpoint device moves out of the service area of ​​the second user plane role network element. Optionally, the second traffic routing rule includes the list of IP addresses and / or the list of domain names that correspond to the first dedicated data network.

[0015] According to the previous project, when the terminal device user moves in and out of a campus, a traffic routing rule can be migrated, thus improving the user experience.

[0016] In one possible project, the method also includes: the first session management network element sends the first tunnel information from the first network element of Petition 870250099131, dated 10 / 29 / 2025, page 12 / 86 6 / 67 user plane function and a third traffic routing rule to a third user plane function network element, wherein the third traffic routing rule instructs the third user plane function network element to send, to the first user plane function network element, a packet that is not for a second dedicated data network and that is sent by the terminal device, and the third user plane function network element is a user plane function network element selected by the first session management network element based on the second dedicated data network. Optionally, the third traffic routing rule includes a list of IP addresses and / or a list of domain names that correspond to the second dedicated data network.

[0017] According to the previous project, a scenario in which a dedicated data network at the visited location (or roaming location) and a dedicated data network at a residential location are overlapped can be supported, to implement two-stage packet routing.

[0018] In one possible design, when the terminal device performs access at the visited location (or roaming location) via 4G (for example, accesses a public land mobile network (PLMN) at the visited location via a 4G network), the first network element of the session management function is a converged network element of the packet data network gateway control plane function and session management at the visited location, and the first network element of the user plane function is a converged network element of the packet data network gateway data plane function and user plane function at the visited location.

[0019] The converged network element of packet data network gateway control plane function and session management can be a device or network element that Petition 870250099131, dated 10 / 29 / 2025, page 13 / 86 7 / 67 converges a session management function (SMF) network element in a 5G network and a packet data network gateway (PGW) control plane function (C) in a 4G network, which may be referred to as the SMF&PGW-C network element. The converged user plane function and packet data gateway function network element may be a device or network element that integrates a user plane function (UPF) network element in the 5G network and a PGW user plane function (U) in the 4G network, which may be referred to as the UPF&PGW-U network element.

[0020] Furthermore, it can be understood that the first network element of the session management function can be not only an SMF&PGW-C network element, but also an SMF&PGW network element or an SMF&PGW-C&PGW-U network element. In other words, when the terminal device accesses the visited location via 4G, the first network element of the session management function can not only have the function of an SMF network element and a PGW-C function, but also have the PGW-U function. The fact that the first network element of the session management function is the SMF&PGW-C network element is merely an example and does not constitute a limitation of this application.

[0021] Similarly, the first user plane function network element can be not only a UPF&PGW-U network element, but also a UPF&PGW network element, or a UPF&PGW-C&PGW-U network element. In other words, when the terminal device accesses the visited location via 4G, the first user plane function network element can not only have the function of a UPF network element and a PGWU function in the 5G network, but also have the function of a PGW-C. The fact that the first user plane function network element is the UPF&PGW-U network element is merely an example and not Petition 870250099131, dated 10 / 29 / 2025, page 14 / 86 8 / 67 constitutes a limitation of this request.

[0022] According to the previous project, in a scenario such as inter-provincial / inter-city roaming, when the terminal device user accesses a roaming location (or a visited location) via 4G, an SMF&PGW-C network element at the roaming location (or the visited location) can create a session based on a dedicated data network identifier, so that the terminal device user can access both a public data network and the dedicated data network. Furthermore, traffic from the public data network can still be sent by a user plane function network element at the visited location to the public data network and is offloaded at the roaming location (i.e., the visited location) to avoid traffic looping.

[0023] According to a second aspect, an embodiment of this application provides a method of communication. The method includes: a first user-plane function network element receives second tunnel information and a first traffic routing rule from a first session management network element, wherein the first session management network element is a session management network element at a visited location of a terminal device, the first user-plane function network element is a user-plane function network element selected for a general data network to which the terminal device subscribes, the second tunnel information is tunnel information from a second user-plane function network element selected for a first dedicated data network to which the terminal device subscribes, and the first traffic routing rule indicates the sending,for the second user plane function network element, of a packet destined for the first dedicated data network and sent by the terminal device; and the first user plane function network element, Petition 870250099131, dated 10 / 29 / 2025, page 15 / 86 9 / 67 The user establishes an uplink tunnel to the second user plane function network element based on the second tunnel information, where the uplink tunnel is used to transmit a packet sent by the first user plane function network element to the second user plane function network element.

[0024] In a possible project, the first traffic routing rule includes a list of IP addresses and / or a list of domain names that correspond / match the first dedicated data network.

[0025] In a possible design, when the first traffic routing rule includes the domain name list corresponding to the first dedicated data network, the method further includes: The first user plane function network element sends a first packet from the terminal device to the second user plane function network element via the uplink tunnel, wherein a first domain name carried in the first packet belongs to the domain name list; the first user plane function network element receives a second packet from the second user plane function network element, wherein the second packet is a response packet to the first packet; and the first user plane function network element associates a source IP address of the second packet to the first domain name.

[0026] In one possible design, the method also includes: The first user plane function network element sends a third packet to the second user plane function network element, where the third packet includes an IP address of the terminal device.

[0027] In a possible design, when the terminal device performs access at the visited location (or roaming location) via 4G (for example, accesses a PLMN at the visited location via a 4G network), the first network element of the management function of Petition 870250099131, dated 10 / 29 / 2025, page 16 / 86 The 10 / 67 session is a converged network element of packet data network gateway control plane function and session management at the visited location, and the first user plane function network element is a converged network element of packet data network gateway data plane function and user plane function at the visited location.

[0028] In a possible project, the method also includes: The first user plane function network element performs 4G and 5G packet format conversion into a packet transmitted between the first dedicated data network and the terminal device.

[0029] According to the previous project, the terminal device can communicate with a dedicated 5G data network in a residential location while accessing the visited location (or roaming location) via 4G.

[0030] According to a third aspect, an embodiment of this request provides a method of communication. The method includes: a second session management network element receives a first request from a first session management network element, wherein the first request includes an identifier of a first dedicated data network to which a terminal device subscribes, the first session management network element is a session management network element at a visited location of the terminal device, and the second session management network element is a session management network element that supports the first dedicated data network;and the second session management network element sends a first response to the first session management network element, wherein the first response includes second tunnel information from a second user plane role network element, and the second user plane role network element is a user plane role network element selected by the second session management network element based on the first data network; Petition 870250099131, dated 10 / 29 / 2025, page 17 / 86 11 / 67 dedicated.

[0031] In a possible design, the first request also includes the first tunnel information from a first user plane function network element; and the method also includes: The second session management network element sends third information to the second user plane function network element, wherein the third information includes the first tunnel information.

[0032] In one possible project, the first request also includes an IP address of the terminal device, and the third piece of information also includes the IP address of the terminal device.

[0033] In one possible project, the third piece of information also includes a dedicated IP address of the terminal device on the first dedicated data network.

[0034] In one possible design, the method also includes: The second session management network element obtains the dedicated IP address from a user data management network element, or obtains the dedicated IP address from a server corresponding to the first dedicated data network, for example, an authentication, authorization, accounting (AAA) server.

[0035] According to a fourth aspect, an embodiment of this application provides a method of communication. The method includes: a second user-plane function network element receives a third packet from a first user-plane function network element, wherein the third packet includes an IP address of a terminal device, the first user-plane function network element is a user-plane function network element selected for a general data network to which the terminal device subscribes, and the second user-plane function network element is a user-plane function network element selected for a first dedicated data network to which the terminal device subscribes; Petition 870250099131, dated 10 / 29 / 2025, page 18 / 86 12 / 67 and the second user plane function network element associate the terminal device's IP address with a dedicated terminal device IP address on the first dedicated data network, where an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation in a packet transmitted between the first dedicated data network and the terminal device.

[0036] In a possible design, the method further includes: The second user plane function network element receives third information from a second session management network element, wherein the third information includes the first tunnel information, the first tunnel identifier is a tunnel identifier of the first user plane function network element, and the second session management network element is a session management network element that supports the first dedicated data network; and the second user plane function network element establishes a downlink tunnel to the first user plane function network element based on the first tunnel information, wherein the downlink tunnel is used to transmit a packet sent by the second user plane function network element to the first user plane function network element.

[0037] In one possible project, the third piece of information also includes the dedicated IP address of the terminal device on the first dedicated data network.

[0038] According to a fifth aspect, an embodiment of this application provides a method of communication. The method includes: a second user plane function network element receives third information from a second session management network element, wherein the third information includes first tunnel information and an IP address of a terminal device, the first tunnel identifier being a Petition 870250099131, dated 10 / 29 / 2025, page 19 / 86 13 / 67 tunnel identifier of a first user plane function network element, the first user plane function network element is a user plane function network element selected for a general data network to which the terminal device subscribes, the second user plane function network element is a user plane function network element selected for a first dedicated data network to which the terminal device subscribes, and the second session management network element is a session management network element that supports the first dedicated data network;and the second user-plane function network element establishes a downlink tunnel to the first user-plane function network element based on the first tunnel information, wherein the downlink tunnel is used to transmit a packet sent by the second user-plane function network element to the first user-plane function network element; and the second user-plane function network element associates the terminal device's IP address with a dedicated terminal device IP address on the first dedicated data network, wherein an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation on a packet transmitted between the first dedicated data network and the terminal device.

[0039] In one possible project, the third piece of information also includes the dedicated IP address of the terminal device on the first dedicated data network.

[0040] According to a sixth aspect, an embodiment of this application provides a communication apparatus. The communication apparatus may be used in a communication apparatus in the first aspect. The communication apparatus may be a first session management network element, a component (for example, a processor, a chip or a system of chips) of Petition 870250099131, dated 10 / 29 / 2025, page 20 / 86 14 / 67 first session management network element, a device that is used in a way that is combined with the first session management network element, or similar.

[0041] In one possible implementation, the communication device may include modules or units that correspond one-to-one to the methods / operations / steps / actions described in the first aspect, for example, a processing unit and an interface unit. The module or unit may be a hardware circuit, may be software, or may be implemented by the hardware circuit in combination with the software.

[0042] According to a seventh aspect, an embodiment of this application provides a communication apparatus. The communication apparatus may be used in a communication apparatus in the second aspect. The communication apparatus may be a first user plane function network element, a component (for example, a processor, a chip or a system of chips) of the first user plane function, an apparatus that is used in such a way as to be compatible with the first user plane function, or the like.

[0043] In one possible implementation, the communication device may include modules or units that correspond, one by one, to the methods / operations / steps / actions described in the second aspect, for example, a processing unit and an interface unit. The module or unit may be a hardware circuit, it may be software, or it may be implemented by the hardware circuit in combination with the software.

[0044] According to an eighth aspect, an embodiment of this application provides a communication apparatus. The communication apparatus may be used in a communication apparatus in the third aspect. The communication apparatus may be a second session management network element, a component (for example, a processor, a chip or a system of chips) of the second session management network element, an apparatus Petition 870250099131, dated 10 / 29 / 2025, page 21 / 86 15 / 67, which is used in combination with the second session management network element, or similar.

[0045] In one possible implementation, the communication device may include modules or units that correspond, one by one, to the methods / operations / steps / actions described in the third aspect, for example, a processing unit and an interface unit. The module or unit may be a hardware circuit, it may be software, or it may be implemented by the hardware circuit in combination with the software.

[0046] According to a ninth aspect, an embodiment of this application provides a communication apparatus. The communication apparatus may be used in a communication apparatus in the fourth or fifth aspect. The communication apparatus may be a second-function user plane network element, a component (for example, a processor, a chip or a system of chips) of a second-function user plane, an apparatus that is used in such a way as to be compatible with the second-function user plane, or the like.

[0047] In one possible implementation, the communication device may include modules or units that correspond, one by one, to the methods / operations / steps / actions described in the fourth or fifth aspect, for example, a processing unit and an interface unit. The module or unit may be a hardware circuit, may be software, or may be implemented by the hardware circuit in combination with the software.

[0048] According to a tenth aspect, an embodiment of this application provides a communication device. The communication device includes an interface circuit and a processor, and the processor and the interface circuit are coupled to each other. The processor is configured to implement, by means of a logic circuit or by executing instructions, the method of Petition 870250099131, dated 10 / 29 / 2025, p. 22 / 86 16 / 67 according to the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect. The interface circuit is configured to receive a signal from a communication device other than the communication device and transmit the signal to the processor, or send a signal from the processor to a communication device other than the communication device. It can be understood that the interface circuit can be a transceiver, a transceiver device, a transceiver unit, or an input / output interface.

[0049] Optionally, the communication device may also include a memory, configured to store instructions executed by the processor, store input data required for the processor to run the instructions, or store data generated after the processor runs the instructions. The memory may be a physically independent unit, or it may be coupled to the processor, or the processor may include the memory.

[0050] According to an eleventh aspect, an embodiment of this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program or instructions. When the computer program or instructions are executed by a processor, the method according to the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect can be implemented.

[0051] According to a twelfth aspect, an embodiment of this application further provides a computer program product, including a computer program or instructions. When the computer program or instructions are executed by a processor, the method according to the first aspect, the second aspect, the third aspect, the fourth aspect or the fifth aspect may be implemented.

[0052] According to a thirteenth aspect, one embodiment of this application also provides a chip system. The Petition 870250099131, dated 10 / 29 / 2025, p. 23 / 86 The 17 / 67 chip system includes a processor, the processor is configured to be coupled to a memory, and the memory is configured to store a program or instructions. When the program or instructions are executed by the processor, the method according to the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect can be implemented.

[0053] According to a fourteenth aspect, an embodiment of this application further provides a communication system. The system may include the first session management network element in the first aspect, the first user plane function network element in the second aspect, the second session management network element in the third aspect, and the second user plane function network element in the fourth or fifth aspect.

[0054] For technical effects that can be achieved from the second to the fourteenth aspect, see the technical effects that can be achieved from the first aspect. Details are not described again in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a diagram of a communication system architecture according to one embodiment of this request; Figure 2 is a ULCL routing diagram according to one embodiment of this application; Figure 3 is a network element deployment diagram for a core network according to one embodiment of this application; Figure 4 is a diagram of a ULCL routing solution according to one embodiment of this application; Figure 5 is a diagram 1 of a communication method according to one modality of this request; Figure 6 is a diagram of a logical relationship of information elements according to one modality of this request; Figure 7 is a diagram 1 of IP address configuration of Petition 870250099131, dated 10 / 29 / 2025, page 24 / 86 18 / 67 in accordance with one of the terms of this request; Figure 8 is a diagram 2 of IP address configuration according to one modality of this request; Figure 9 is a diagram 2 of a communication method according to one modality of this request; Figure 10 is a two-stage routing diagram according to one modality of this request; Figure 11 is a packet routing diagram for a terminal device according to one mode of this request; Figure 12 is a diagram 3 of a communication method according to one modality of this request; Figure 13 is diagram 1 of a communication device structure according to an embodiment of this application; and Figure 14 is diagram 2 of a communication device structure according to an embodiment of this application. DESCRIPTION OF THE MODALITIES

[0056] To facilitate understanding by a person skilled in the art, some terms in the modalities of this request are first explained and described.

[0057] (1) A dedicated data network (DN) may also be called a special data network, dedicated network, private network or similar, it is usually an internal network and may be a company intranet, a campus intranet, a shopping center / supermarket intranet or similar.

[0058] (2) A general DN may also be called a public network, big network or similar, it is usually the internet (internet), or it may be an access point or an access network for an operator to access the internet, for example, a 3gnet from China Unicom.

[0059] (3) Anchor UPF network element: In embodiments of this application, each UPF network element that can communicate with a DN via an N6 interface may be referred to as an anchor UPF network element or referred to as an element Petition 870250099131, dated 10 / 29 / 2025, page 25 / 86 19 / 67 UPF network with an anchor function.

[0060] The technical solutions in examples in this application can be applied to various communication systems, for example, to communication systems such as a 4th generation (4G) communication system and a 5th generation (5G) communication system, and can also be applied to a communication system developed after 5G, for example, a 6th generation (6G) communication system. The following describes some network architectures to which this application applies. In the following description, an example is used in which a terminal device is user equipment (UE).

[0061] Figure 1 is a diagram of a possible 5G network architecture to which this application applies. The 5G network architecture includes a UE, a data network (DN), and a carrier network. The carrier network may include one or more of the following network elements (or devices): an access network (AN) or a radio access network (RAN), a user plane function (UPF) network element, an access and mobility management function (AMF) network element, a session management function (SMF) network element, a policy control function (PCF) network element, an application function (AF) network element, a network slice selection function (NSSF) network element,an authentication server function (AUSF) network element, a user data management (UDM) network element, and a network slice-specific authentication and authorization function (network, Petition 870250099131, dated 10 / 29 / 2025, page 26 / 86 20 / 67 slice-specific authentication and authorization function (NSSAAF). In the carrier network, a network element or device other than the access network device may be referred to as a core network element or core network device. It should be understood that there may be one or more network elements / devices as shown in Figure 1 during deployment.

[0062] Terminal device: The terminal device and an access network device communicate using a specific air interface technology. An air interface can be a radio air interface based on a 5G standard. For example, the air interface is a new radio (NR) air interface. Alternatively, the air interface can be an air interface based on a next-generation 5G mobile communication network technology standard. Alternatively, the air interface can be an air interface based on a 4G standard (e.g., a long-term evolution (LTE) system).The terminal device can be user equipment (UE), a portable terminal, a notebook computer, a subscriber unit, a cellular phone, a smartphone, a wireless data card, a personal digital assistant (PDA) computer, a tablet computer, a wireless modem, a handheld device, a laptop computer, a cordless phone, a machine-type communication (MTC) terminal, or any other device that can access a network.

[0063] Access Network Device: The access network device is primarily responsible for functions such as radio resource management, quality of service (QoS) management, and data compression and encryption on the air interface side. The access network device can be a base station, a pole site, a Petition 870250099131, dated 10 / 29 / 2025, page 27 / 86 21 / 67 integrated access and backhaul node (Integrated Access and Backhaul, IAB), a NodeB (NodeB), a mobile base station, an evolved NodeB (evolved NodeB, eNodeB), a transmit and receive point (transmit-receive point, TRP), a radio access network, a radio access network device, an evolved NodeB (evolved NodeB, eNodeB) in an LTE system or an LTE Advanced system (LTE-Advanced, LTE-A), a next-generation NodeB (gNB) in a 5G mobile communication system, a NodeB in a future mobile communication system or similar, or it may be a module or unit that completes some functions of the base station, for example, it may be a central unit (CU) or it may be a distributed unit (DU).The radio access network device may be a macro base station, a micro base station (also called a small cell), or an indoor base station, or it may be a relay node, a donor node, or the like. The specific technology and specific device form factor used by the access network device are not limited in the embodiments of this application.

[0064] Furthermore, the access network device may alternatively be an unreliable access network device not belonging to a 3rd generation partnership project (3GPP). The unreliable access network device not belonging to a 3rd generation partnership project may allow a terminal device to interconnect to a 3GPP core network using a non-3GPP technology. Non-3GPP technology includes, for example, wireless fidelity (Wi-Fi), worldwide interoperability for microwave access (WiMAX), and code division multiple access (CDMA), and may directly access the 3GPP core network compared to a non-3GPP access network device. Petition 870250099131, dated 10 / 29 / 2025, page 28 / 86 22 / 67 reliable. The network element needs to interconnect to a 3GPP core network via a security tunnel configured by a security gateway. The security gateway is, for example, an evolved packet data gateway (ePDG) or a non-3GPP interworking function (N3IWF) network element.

[0065] AMF Network Element: The AMF network element is a core network element and is primarily responsible for signaling processing, for example, functions such as access control, mobility management, connection and disconnection, and gateway selection. When serving a session on an endpoint device, the AMF network element can provide a storage resource in the control plane for the session and store a session identifier, an SMF network element identifier associated with the session identifier, and the like.

[0066] SMF Network Element: The SMF network element is responsible for user plane network element selection, user plane network element redirection, internet protocol (IP) address assignment, carrier configuration, modification and release, and QoS control.

[0067] UPF Network Element: The UPF network element is responsible for forwarding and receiving user data on a terminal device. The UPF network element can receive user data from a data network and transmit the user data to the terminal device via an access network device. Alternatively, the UPF network element can receive user data from the terminal device via the access network device and forward the user data to the data network. A transmission feature and a scheduling function in the network element of Petition 870250099131, dated 10 / 29 / 2025, page 29 / 86 23 / 67 UPFs that provide a service to the terminal device are managed and controlled by the SMF network element. [00 68]PCF Network Element: The PCF network element primarily supports providing a unified policy framework to control network behavior and providing a policy rule for a control layer network function, which is responsible for obtaining policy-related user subscription information.

[0069] AUSF Network Element: The AUSF network element primarily provides an authentication function and supports 3GPP access authentication and non-3GPP access.

[0070] NEF Network Element: The NEF network element primarily supports secure interaction between a 3GPP network and a third-party application. The NEF network element can securely expose a network capacity and an event to third parties to enhance or improve the application's quality of service. The 3GPP network can also securely obtain related third-party data to enhance intelligent network decision-making. Additionally, the network element supports the restoration of structured data from a unified data repository or the storage of structured data in the unified data repository.

[0071] UDM Network Element: The main functions of the UDM network element include: support for authentication credential processing, user identity processing, access authorization, record and mobility management, signature management, short message service management and the like in a 3GPP authentication and key agreement mechanism.

[0072] UDR Network Element: The UDR network element is primarily responsible for storing structured data. The stored content includes subscription data and policy data, externally exposed structured data, and data Petition 870250099131, dated 10 / 29 / 2025, page 30 / 86 24 / 67 related to the application. [007 3]NRF Network Element: The main functions of the NRF network element include: a service discovery function, maintenance of an available network function (NF), text of an NF instance and a service supported by it.

[0074] NSSF Network Element: The main functions of the NSSF network element include: selecting a group of network slice instances for a terminal device, determining allowed NSSAI, determining a set of AMF network elements that can serve the terminal device, and so on. [007 5]AF Network Element: The AF network element primarily supports interaction with a 3GPP core network to provide a service, for example, by influencing a data routing decision and a policy control function, or by providing some third-party services to a network side.

[0076] An N4 interface is an interface through which a control plane SMF network element is connected to a user plane UPF network element. The SMF network element can interact with the UPF network element through the N4 interface to complete the creation, modification, release, and the like of a user plane session, so that a user (i.e., UE) accesses the internet through the UPF network element.

[0077] An N9 interface is a user-plane interface between an intermediate UPF (intermediate, I) and a UPF, and is used to transmit uplink and downlink user data streams between UPF network elements. When an anchor UPF network element can cover a user's location, the anchor UPF network element is directly connected to a (R)AN via an N3 interface. When an anchor UPF network element cannot cover the Petition 870250099131, dated 10 / 29 / 2025, page 31 / 86 25 / 67 user location, an I-UPF network element is inserted between the anchor UPF network element and a (R)AN, the I-UPF network element is decoupled from the (R)AN via an N3 interface and is connected to the anchor UPF network element via an N9 interface. In another possible scenario, when a user needs to perform routing locally, a ULCL UPF network element can be connected separately to a secondary anchor UPF network element and a primary anchor UPF network element via an N9 interface.

[0078] An N7 interface is an interface between an SMF network element and a PCF network element. The SMF network element can obtain a session policy from the PCF network element through the N7 interface.

[0079] An N16a interface is an interface between an I-SMF and an SMF. When a user accesses a roaming location while roaming between provinces (between areas), an I-SMF network element in a visited (or roaming) province can be connected to an SMF network element in a home province via the N16a interface to transmit session information.

[0080] In Figure 1, N1, N2, N5, N6, N7, N8, N10, N11, N12, N13, N15, N22, N58, and N59 are interface sequence numbers. For example, to obtain the meaning of the interface sequence number, refer to a definition in the 3GPP standard protocol.

[0081] Figure 2 is a ULCL routing diagram according to one embodiment of this request. A UPF ULCL network element can perform traffic routing in user data and separately route a user's packets to a PDU Session Anchor (PSA), a UPF 2 network element (a secondary UPF anchor), and a UPF PSA 1 network element (a primary UPF anchor) according to a ULCL rule. The UPF ULCL network element is a UPF network element that possesses or supports the function of a ULCL, and a PSA network element is a UPF network element. Petition 870250099131, dated 10 / 29 / 2025, page 32 / 86 26 / 67 that possesses or supports the function of a PSA. The PSA is a PDU session anchor and a processing point for terminating a General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel. Only a UPF network element acting as a PSA or a UPF network element with the PSA function can be connected to a DN via an N6 interface. The UPF PSA1 network element and the UPF PSA2 network element can separately provide N6 interfaces to direct packets to different DNs. The UPF ULCL network element identifies uplink packets (or traffic) according to a traffic routing rule and determines whether the packet should be sent to a primary or secondary anchor.Generally, a packet that meets the traffic routing rule accesses a local DN via an N6 interface of the secondary anchor, and another packet is sent to the primary anchor via a GTP tunnel from an N9 interface to access the internet.

[0082] The 5G network architecture is still used for description. Refer to a network element deployment diagram of a core network shown in Figure 3. An AMF network element, an SMF network element, a PCF network element, a charging function (CHF) network element, and the like are generally deployed by province. A primary anchor UPF network element, functioning as a public network UPF network element, is deployed by city or province and interconnects to the internet (i.e., a public DN). A ULCL UPF network element and a secondary anchor UPF network element, serving as dedicated network UPF network elements, are generally co-deployed at the edge of a carrier network and close to a campus DN (i.e., a dedicated DN).

[0083] Refer to a ULCL routing solution shown in Figure 4. For an intranet (a data network) Petition 870250099131, dated 10 / 29 / 2025, p. 33 / 86 If a dedicated 27 / 67 network element is located in a residential area and a terminal device subscribes to it, the terminal device can route packets to the intranet and the internet (a public data network) via a dedicated UPF network element in a city where the intranet is located. However, an AMF network element, an SMF network element, a PCF network element, and similar elements are generally deployed by province. While SMF and UPF network elements in all provinces and cities support internet access, there is a large number of dedicated data networks for services and similar purposes. A traffic routing rule for a packet to a dedicated data network is usually pre-configured or defined only on an SMF or UPF network element at a dedicated data network location, and a user performs access while roaming between provinces / cities using an SMF / UPF in a roaming province / city as an anchor.Due to reasons such as the SMF network element in the roaming province / city not being able to directly manage a UPF network element in a home province / city, and the packet traffic routing rule to the dedicated data network usually being pre-configured or defined only on the network element or UPF network element at the dedicated data network location, there is a problem: the user cannot continue accessing the dedicated data network and can only access the internet upon leaving the dedicated data network location. While a solution exists where all traffic from a user in a roaming location is considered to be returned to a home province for processing, in that solution, traffic from a public data network also needs to be returned to the home province for processing, resulting in traffic looping.Furthermore, when all user traffic at the roaming location is returned to the home province for processing, the home province (e.g., an SMF network element in the province). Petition 870250099131, dated 10 / 29 / 2025, page 34 / 86 28 / 67 (origin) allocates a session IP address to the user instead of allocating the IP address by roaming location. This does not conform to the IP address allocation specification.

[0084] In view of this, this application provides a method and a communication device for creating a session via an SMF network element at a visited location (or roaming location) based on an identifier of a dedicated data network, so that a terminal device user can access both a public data network and the dedicated data network. Furthermore, traffic from the public data network is offloaded at the visited location (or roaming location) to avoid traffic looping. The following describes in detail the embodiments of this application with reference to the accompanying drawings.

[0085] It should be understood that, in embodiments of this application, a user plane function network element may be the former UPF network element or may be a network element that has a function of the former UPF network element in a future communication system, such as a 6G system. A session management network element may be the former SMF network element or may be a network element that has a function of the former SMF network element in a future communication system, such as a 6G system. A network repository function network element may be the former NRF network element or may be a network element that has a function of the former NRF network element in a future communication system, such as a 6G system.Similarly, a policy control network element may be the former or similar PCF network element, or it may be a network element or similar that has a function of the former PCF network element in a future communication system, such as a 6G system. The specific forms of the user plane function network element, session management network element, and the like are not limited to the embodiments of this application. Petition 870250099131, dated 10 / 29 / 2025, page 35 / 86 29 / 67 To facilitate description, in the modalities of this application, an example is used where the user plane function network element is the UPF network element, the session management network element is the SMF network element, and the network repository function network element is the NRF network element.

[0086] Furthermore, it should be understood that ordinal numbers such as first and second, mentioned in the modalities of this application, are used to distinguish between a plurality of objects and not to limit sizes, content, sequence, temporal sequence, priorities, degrees of importance or the like of the plurality of objects. For example, a first session management network element and a second session management network element do not indicate that the two network elements correspond to different priorities, degrees of importance or the like.

[0087] Figure 5 is a diagram of a communication method according to one modality of this request. The method includes the following steps.

[0088] S501: A PCF network element sends the first information to a first SMF network element, and correspondingly, the first SMF network element receives the first information.

[0089] The initial information includes an identifier of a first dedicated DN (for example, a data network name (DNN) of the first dedicated DN) to which a terminal device subscribes, and the first SMF network element is an SMF network element at a visited location of the terminal device.

[0090] In this type of request, the initial information may be policy / decision information delivered by the PCF network element to the first SMF network element.

[0091] In one possible implementation, upon receiving a Petition 870250099131, dated 10 / 29 / 2025, p. 36 / 86 30 / 67 In the procedure for establishing or updating a session on an AMF network element, the first SMF network element can initiate a session management policy association establishment / modification procedure with the PCF network element, and the PCF network element can deliver, to the first SMF network element in the session management policy association establishment / modification procedure, the initial information, including information such as the identifier of the dedicated DN to which the terminal device subscribes and a traffic routing policy for a packet (or traffic) from the terminal device.

[0092] In another possible implementation, the PCF network element can actively deliver the first information to the first SMF network element when it identifies that the user subscription information of the terminal device changes (for example, a service subscribed to by the terminal device changes from a public network service to a public network service and a first dedicated network service) and the user establishes a session.

[0093] After obtaining, based on the initial information from the PCF network element, the identifier (e.g., the DNN) of the first dedicated DN to which the terminal device subscribes, the first SMF network element can determine information about a second SMF network element that supports the first dedicated DN. [00 94] In one example, as a network element serving as a network repository function, an NRF network element can receive and store information about a supported dedicated DN registered by an SMF network element. The dedicated DN supported by the SMF network element can be a dedicated DN in a deployment area of ​​the SMF network element, and the information about the dedicated DN registered by the SMF network element can Petition 870250099131, dated 10 / 29 / 2025, page 37 / 86 31 / 67 include information such as an identifier (e.g., a DNN) of the dedicated DN. After obtaining the identifier of the first dedicated DN to which the terminal device subscribes, the first SMF network element can query, via the NRF network element, the SMF network element through which the first dedicated DN is registered, to obtain information about the second SMF network element that supports the first dedicated DN, for example, information such as an IP address and an identifier of the second SMF network element.

[0095] In some implementations, the first SMF network element locally stores a network element, for example, a UDM network element may also store an association relationship between information about some SMF network elements and a dedicated DN registered by the SMF network element, and the first SMF network element may also obtain, through the first SMF network element or the network element, for example, the UDM, information about the second SMF network element that supports the first dedicated DN.

[0096] Furthermore, it can be understood that the first information delivered by the PCF network element may also include an identifier of a general DN (for example, a DNN of the general DN) to which the terminal device subscribes, and the first SMF network element may also create a session based on the general DN identifier, for example, a session between the terminal device and the general DN, so that the terminal device can perform a general DN service.

[0097] S502: The first SMF network element sends a first request to the second SMF network element, and correspondingly, the second SMF network element receives the first request.

[0098] After determining the second SMF network element that supports the first dedicated DN, the first SMF network element can send the first request, including the Petition 870250099131, dated 10 / 29 / 2025, page 38 / 86 32 / 67 identifier of the first dedicated DN, for the second SMF network element. The first request can be an activation request, a DNN activation request, a dedicated DNN activation request, or similar. In one example, in the first request, the identifier of the first dedicated DN (e.g., the DNN of the first dedicated DN) can be carried by a DNN information element in the request; or the general DNN can be carried by a DNN information element, and the identifier of the first dedicated DN is carried by a selected DNN information element.

[0099] In some implementations, to facilitate sending a downlink packet from the first dedicated DN to the terminal device, the first request may also carry the first tunnel information from a first UPF network element, where the first UPF network element is a UPF network element selected by the first SMF network element based on the general DN to which the terminal device subscribes, the first tunnel information may include an IP address and / or a tunnel identifier (e.g., a tunnel endpoint identifier (TEID)) of the first UPF network element.

[00100] S503: The second SMF network element sends a first response to the first SMF network element, and correspondingly, the first SMF network element receives the first response.

[00101] After receiving the first request, the second SMF network element can select, based on the identifier (e.g., the DNN) of the first dedicated DN, a UPF anchor network element corresponding to the first dedicated DN, i.e., a second UPF network element, and send the first response to the first SMF network element, including the second tunnel information from the second UPF network element. The second tunnel information from the second Petition 870250099131, dated 10 / 29 / 2025, page 39 / 86 33 / 67 UPF network element may include an IP address and / or a tunnel identifier (e.g., a TEID) of the second UPF network element.

[00102] Furthermore, the second SMF network element can also send third information, including the first tunnel information from the first UPF network element, to the second UPF network element, so that the second UPF network element can establish a downlink tunnel to the first UPF network element based on the first tunnel information from the first UPF network element. The downlink tunnel can be used to transmit a packet sent by the second UPF network element to the first UPF network element.

[00103] S504: The first SMF network element sends the second information to the first UPF network element, and correspondingly, the first UPF network element receives the second information.

[00104] The second information includes the second tunnel information and a first traffic routing rule, and the first traffic routing rule indicates the sending (or routing) to the second UPF network element of a packet destined for the first dedicated DN and sent by the terminal device. It should be understood that the packet destined for the first dedicated DN and sent by the terminal device can also be understood as a packet sent by the terminal device whose destination address is the first dedicated DN, or a packet sent by the terminal device to the first dedicated DN.

[00105] After receiving the second tunnel information from the second UPF network element and the first traffic routing rule, the first UPF network element can establish an uplink tunnel to the second UPF network element based on the second information. Petition 870250099131, dated 10 / 29 / 2025, page 40 / 86 34 / 67 Tunnel. The uplink tunnel can be used to transmit a packet sent by the first UPF network element to the second UPF network element. Additionally, the packet sent by the terminal device can be routed according to the first traffic routing rule. For example, the packet destined for the first dedicated DN sent by the terminal device is identified, and the packet from the first dedicated DN is sent to the second UPF network element through the uplink tunnel established for the second UPF network element. For a packet that is not destined for the first dedicated DN (e.g., a packet destined for the general DN) and that originates from the terminal device, the first user plane function network element can send (or forward) the packet to a public DN.

[00106] In one possible implementation, the first traffic routing rule may include a list of IP addresses and / or a list of domain names belonging to the first dedicated DN. The list of IP addresses may include one or more IP addresses corresponding to the first dedicated DN, and the list of domain names may include one or more domain names corresponding to the first dedicated DN. For example, the list of domain names may include a plurality of domain names from a network or network subdirectory corresponding to the first dedicated DN, and the list of IP addresses may include IP addresses corresponding, respectively, to networks or network subdirectories corresponding to the first dedicated DN.

[00107] For example, the first traffic routing rule includes the list of IP addresses corresponding to the first dedicated DN. After receiving the packet from the terminal device, the first UPF network element can identify a destination IP address for the packet. If the destination IP address of the packet belongs to the list of IP addresses corresponding to the first dedicated DN, the first UPF network element can Petition 870250099131, dated 10 / 29 / 2025, p. 41 / 86 35 / 67 send (or route) the packet to the second UPF network element; otherwise, the first UPF network element sends (or routes) the packet to the public DN.

[00108] For example, the first traffic routing rule includes the list of domain names corresponding to the first dedicated DN. After receiving the packet from the terminal device, the first UPF network element can identify a domain name contained in the packet. If the domain name contained in the packet belongs to the list of domain names corresponding to the first dedicated DN, the first UPF network element can send (or route) the packet to the second UPF network element; otherwise, the first UPF network element sends (or routes) the packet to the public DN.

[00109] In one possible implementation, the list of IP addresses and / or the list of domain names that match / correspond to the first dedicated DN can be obtained based on the first information (e.g., policy / decision information) provided by the PCF network element.

[00110] Figure 6 is a diagram of a logical relationship of information elements transmitted through an N7 interface between the PCF network element and the first SMF network element. In this embodiment of this request, the policy / decision information (Smpolicydeciston) may carry a PCC rules-rule1 field from a public network service rule (e.g., a general DN), a PCC rules-rule2 field from a dynamic traffic routing rule of a dedicated network service (e.g., the first dedicated DN), and a flow information field, and the like. Based on this, a field (e.g., a CrossServiceAreaULCLRuleIndicator) may be extended in the PCC rule to indicate that the rule is used to route a packet (or traffic) from an end-user device during Petition 870250099131, dated 10 / 29 / 2025, page 42 / 86 36 / 67 Roaming between areas. A flow description list field (flowDescriptionList) and a host list field (hostlist) are extended in the flowinformation field to carry (or support) a list of IP addresses and a list of domain names that correspond to a dedicated network (e.g., the first dedicated DN). Alternatively, a selected DNN field can be extended in a RouteToLocation field (RouteToLocation) to carry an identifier of a dedicated network (e.g., the DNN of the first dedicated DN) at a source location, and a dedicated network slice field (dedicatedNetworksnssai) can be extended to carry slice information of a dedicated network (e.g., slice information of the first dedicated DN).In addition, the Smpolicydecision can also carry a reference data field (Reftcdata), a precedence field (precedence), a traffic control data field (Trafficcontroldata), a DN access identifier (DN access identifier, DNAI), and a tcId field, where the tcId field can be used to uniquely identify traffic control policy data within a PDU session (uniquely identifies traffic control policy data within a PDU session).

[00111] In some implementations, the first SMF network element may alternatively obtain, via a network element, for example, the second SMF network element that supports the first dedicated DN, the list of IP addresses and / or the list of domain names that correspond / match the first dedicated DN. This is not limited to this application.

[00112] Furthermore, when the first traffic routing rule includes the domain name list corresponding to the first dedicated DN, after receiving, from the terminal device, a first packet (for example, a Domain Name System (DNS) request packet) that carries a first domain name belonging to the domain name list, Petition 870250099131, dated 10 / 29 / 2025, page 43 / 86 37 / 67 The first UPF network element can send the first packet to the second UPF network element, parse a second packet (e.g., a DNS response packet) from the second UPF network element to obtain a source IP address from the second packet, and associate the source IP address of the second packet with the first domain name. According to the previous method, the first UPF network element can learn an IP address corresponding to a domain name. After subsequently receiving a packet whose destination address is the IP address, the first UPF network element can also send (or route) the packet to the second UPF network element based on the IP address, to transmit the packet to the first dedicated DN.

[00113] It should be understood that, in this embodiment of this request, for a traffic routing rule stored in the SMF network element, in the PCF network element, in the UPF network element or similar, for example, the first traffic routing rule, an IP address and / or a domain name that corresponds / matches a dedicated DN (for example, a campus DN) can be aggregated at a dedicated DN granularity, to optimize a data structure and reduce memory overheads.

[00114] In some implementations, after the first SMF network element creates a session with the first dedicated DN, the first UPF network element sends a third packet to the second UPF network element, carrying an IP address of the terminal device. In one example, the third packet might be a packet actively constructed by the first UPF network element. A source IP address in GTP (GRPS tunneling protocol user plane, GTP-U) packet encapsulation can be the IP address of the terminal device. The terminal device IP address can be an IP address of the terminal device at a visited location, for example, an IP address Petition 870250099131, dated 10 / 29 / 2025, page 44 / 86 38 / 67 public IP address of the terminal device on a public DN. The public IP address of the public DN may also be referred to as a public network IP address or similar, and may be allocated to the terminal device by the first SMF network element or similar at the visited location, for example, being allocated to the terminal device in a process in which the first SMF network element establishes a session from the terminal device to the public DN.

[00115] After receiving the third packet, the second UPF network element can associate the terminal device's IP address with a dedicated IP address of the terminal device in the first dedicated DN, where an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation in a packet transmitted between the first dedicated DN and the terminal device. For a downlink packet between the first dedicated DN and the terminal device, the dedicated IP address (i.e., a dedicated network IP address) can be replaced by the terminal device's IP address (i.e., a public or public network IP address). For an uplink packet between the first dedicated DN and the terminal device, the terminal device's IP address (i.e., a public or public network IP address) is replaced by the dedicated IP address (i.e., a dedicated network IP address).One-to-one address translation between the IP address (i.e., public or public network IP address) of the terminal device and the dedicated IP address (i.e., dedicated network IP address) is supported. It should be understood that address translation in the modes of this application can be used for translation or replacement of IP addresses at a network layer (layer 3), an application layer, or similar.

[00116] Furthermore, a private GTPU extension header (e.g., a GTPU packet header) carried in the third packet sent by the first UPF network element may also carry indication information indicating that the third packet Petition 870250099131, dated 10 / 29 / 2025, page 45 / 86 39 / 67 is a packet constructed by the network. The second UPF network element may not carry the third packet that carries the indication information; the third packet is not forwarded to the first dedicated DN and may only be used to obtain the IP address of the terminal device that is allocated at the visited location (or roaming location).

[00117] In some implementations, the first SMF network element may send the terminal device's IP address to the second SMF network element, and the second SMF network element sends the terminal device's IP address to the second UPF network element. In one example, when the first SMF network element sends the first request to the second SMF network element via an N16a interface, the first request may carry the terminal device's IP address. When the second SMF network element sends the third piece of information to the second UPF network element, including the first tunnel information from the first UPF network element, the third piece of information may carry the terminal device's IP address and similar information, so that the second UPF network element becomes aware of the terminal device's IP address at the visited location (or roaming location).

[00118] It should be understood that, in embodiments of this request, the dedicated IP address of the terminal device in the first dedicated DN may be allocated to the terminal device by the second UPF network element, or it may be allocated to the terminal device by the second SMF network element, the UDM network element, or a server corresponding to the first dedicated DN, for example, an authentication, authorization, accounting (AAA) server, and is delivered to the second UPF network element by the second SMF network element and the like. For example: the second SMF network element may also include, in the third information sent to the second UPF network element, the Petition 870250099131, dated 10 / 29 / 2025, page 46 / 86 40 / 67 dedicated IP address of the terminal device in the first dedicated DN.

[00119] As shown in Figure 7, the UDM network element can store information about the general DN and the dedicated DN (e.g., the first dedicated DN) to which the terminal device subscribes, and can also store or configure a dedicated (static) IP address to which the terminal device subscribes in the first dedicated DN.After the second SMF network element receives the first request (including the identifier of the first dedicated DN and the IP address (the public or public network IP address) of the terminal device) from the first SMF network element, the second SMF network element can query, through the UDM network element, the dedicated IP address to which the terminal device subscribes in the first dedicated DN, and can include, in the third piece of information sent to the second UPF network element, the dedicated IP address and the IP address (public or public network IP address) of the terminal device, so that the second UPF network element can associate the IP address of the terminal device with the dedicated IP address of the terminal device in the first dedicated DN, to perform address translation in a packet transmitted between the first dedicated DN and the terminal device.

[00120] As shown in Figure 8, after the second SMF network element receives the first request (including the identifier of the first dedicated DN and the IP address (the public or public network IP address) of the terminal device) from the first SMF network element, the second SMF network element can obtain, through an AAA server associated with the first dedicated DN, the dedicated IP address allocated to the terminal device in the first dedicated DN by the AAA server, and can include, in the third piece of information sent to the second UPF network element, the dedicated IP address of Petition 870250099131, dated 10 / 29 / 2025, page 47 / 86 41 / 67 terminal device in the first dedicated DN and the IP address (the public or public network IP address) of the terminal device, so that the second UPF network element can associate the terminal device's IP address with the dedicated IP address of the terminal device in the first dedicated DN, to perform address translation in a packet transmitted between the first dedicated DN and the terminal device. Furthermore, it should be understood that the data or information exchanged between the second SMF network element and the AAA server can be routed through the second UPF network element or similar.

[00121] In some implementations, the second SMF network element may also obtain a cluster of dedicated IP addresses from the first dedicated DN via a server associated with the first dedicated DN, for example, the AAA server. The cluster of dedicated IP addresses includes a plurality of dedicated IP addresses. After the second SMF network element obtains the cluster of dedicated IP addresses from the AAA server, the second SMF network element may allocate a dedicated IP address from the cluster of dedicated IP addresses to the terminal device, or it may send the cluster of dedicated IP addresses to the second UPF network element, and the second UPF network element allocates a dedicated IP address from the cluster of dedicated IP addresses to the terminal device.

[00122] A communication method provided in an embodiment of this application is described using an example wherein a first dedicated DN is a campus DN, a public DN is the internet, and a terminal device accesses a campus DN at a source location from a terminal device at a roaming location. The method may include the following steps.

[00123] S901: A second SMF network element at an initial location registers a first supported dedicated DN with an NRF network element. Petition 870250099131, dated 10 / 29 / 2025, page 48 / 86

[00124] S902: A PCF network element sends the first information to a first SMF network element at a roaming location.

[00125] The initial information may include a campus DN identifier to which the terminal device subscribes (e.g., a campus DN DNN) and a list of IP addresses and / or a list of domain names that correspond / match the campus DN.

[00126] S903: The first SMF network element at the roaming location obtains information about the second SMF network element at the origin location via the NRF network element.

[00127] S904: The first SMF network element at the roaming location sends a first wake-up request to the second SMF network element at the home location, where the first wake-up request carries the campus DN identifier.

[00128] S905: The second SMF network element at the initial location selects a second UPF network element for the campus DN based on the campus DN identifier.

[00129] Furthermore, the first activation request may still carry the first tunnel information from a first UPF network element, and the second SMF network element at the initial location may still send the first tunnel information to the second UPF network element, so that the second UPF network element establishes a downlink tunnel to the first UPF network element.

[00130] S906: The second SMF network element at the initial location sends a first activation response to the first SMF network element at the roaming location, where the activation response ports second tunnel information from the second UPF network element.

[00131] S907: The first SMF network element at the roaming location sends a second set of information to the first UPF, where the second set of information includes the second set of information. Petition 870250099131, dated 10 / 29 / 2025, page 49 / 86 43 / 67 tunnel and a first traffic direction rule.

[00132] The first traffic routing rule indicates the sending, to the second UPF network element, of a packet that is for the campus DN and that is sent by the terminal device. The first UPF network element can establish an uplink tunnel to the second UPF network element based on the second tunnel information and can route, according to the first traffic routing rule, a packet destined for the campus DN and that is from the terminal device, and a packet destined for the internet and that is from the terminal device.For example, the packet destined for the campus network domain (DN) and originating from the terminal device is sent to the second UPF network element via the uplink tunnel established between the second UPF network element and the first UPF network element, so that the second UPF network element forwards the packet to the campus network domain; and the packet destined for the internet and originating from the terminal device is sent to the internet.

[00133] Furthermore, the first UPF network element can also construct a GTPU packet that carries an IP address allocated to the terminal device by the first SMF network element, the first UPF network element, or similar, and send the GTPU packet to the second UPF network element. The second UPF network element associates the terminal device's IP address with a dedicated IP address of the terminal device in the campus DN, to perform address translation and similar in a packet transmitted between the campus DN and the terminal device.

[00134] For an implementation of the communication method shown in Figure 9, see the descriptions of the communication method shown in Figure 5. Details are not described again.

[00135] Furthermore, considering some scenarios, some DNs Petition 870250099131, dated 10 / 29 / 2025, page 50 / 86 Dedicated DNs (Network Names) for implementing a specific service can be deployed in a specific area. Regardless of whether the terminal device user is located in a specific location (e.g., city or province) within the dedicated DN for that service, the dedicated DN for that service can be used when the terminal device user enters the specific service area. In this application mode, multi-stage routing of a terminal device packet can be supported.

[00136] For example, when there is a second dedicated DN at the visited (or roaming) location of the terminal device, a first SMF network element at the visited location may still send the first tunnel information from the first UPF network element and a third traffic routing rule to a third UPF network element. The third traffic routing rule indicates that the third user plane function network element should send, to the first UPF network element, a packet that is sent by the terminal device and that is not for the second dedicated DN. The third UPF network element is a UPF network element selected by the first SMF network element based on the second dedicated DN, and the third traffic routing rule may include a list of IP addresses and / or a list of domain names that correspond to the second dedicated DN.

[00137] See Figure 10. For example, the second dedicated DN is a shopping center / supermarket DN, the first dedicated DN is a campus DN, a general DN is the Internet, and the terminal device is a dual-domain user of the campus and Internet DNs. The third UPF network element at the roaming location has the function of a ULCL + secondary anchor (corresponding to an anchor of the shopping center / supermarket DN) and can perform one-stage routing on a packet from the terminal device, according to the Petition 870250099131, dated 10 / 29 / 2025, page 51 / 86 45 / 67 third traffic routing rule, to send a packet from the terminal device destined for the shopping center / supermarket DN to the shopping center / supermarket DN and send a packet from the terminal device not destined for the shopping center / supermarket DN (e.g., a packet for the campus DN and the Internet) to the first UPF network element. The first UPF network element has the primary anchor function (corresponding to an internet anchor) and can perform two-stage routing of a packet from the third UPF network element, according to the first traffic routing rule, to send a packet for the campus DN to the second UPF network element and then send a packet to the internet.Furthermore, the first SMF network element can also deliver the first traffic routing rule, a rule for charging a packet (or traffic) for the campus DN, a rule for charging a packet (or traffic) for the internet, a rule for charging a packet (or traffic) for the shopping mall / supermarket DN, and similar to the third UPF network element, to charge the traffic of the terminal device.

[00138] In the example in Figure 10, through two-stage routing, the packet sent by the terminal device that is destined for the Internet can be offloaded at the roaming location, and traffic from a campus DN at a residential location can be routed to a second UPF network element that serves as a campus DN anchor at the residential location.

[00139] In some implementations, when the visited location of the terminal device is the same as the location of the first dedicated DN, for example, in the same province or city, the communication method of this request can also be used. In other words, a second SMF network element at the visited location and a first SMF network element supporting the first dedicated DN can alternatively be the same network element. Petition 870250099131, dated 10 / 29 / 2025, p. 52 / 86 46 / 67 of the SMF.

[00140] Refer to the packet routing diagram of a terminal device shown in Figure 11. In Figure 11, an intranet identifies the first dedicated DN and the internet identifies the public DN. When the terminal device is located in a service area of ​​the second UPF network element, the first SMF network element (for example, an SMF network element in Figure 11) can send fourth pieces of information to the second UPF network element, where the fourth pieces of information include the first tunnel information from the first UPF network element and the second traffic routing rule.The second traffic routing rule may include the list of IP addresses and / or the list of domain names that correspond to the first dedicated DN, and the second traffic routing rule indicates that the second UPF network element should send, to the first UPF network element, a packet that is not for the first dedicated DN and that is sent by the terminal device. When the first SMF determines that the terminal device leaves the service area of ​​the second UPF network element, the first SMF network element may send the second information to the first UPF network element, where the second information includes the second tunnel information and the first traffic routing rule.

[00141] In other words, when the terminal device is located within the service scope of the first dedicated DN (for example, a campus corresponding to the first dedicated DN), the SMF network element can deliver a traffic routing rule to the second UPF network element (i.e., a dedicated network UPF corresponding to the dedicated DN), and the second UPF is used to perform packet routing. When the terminal device is located outside the service scope of the first dedicated DN, the SMF network element can deliver the traffic routing rule to the first Petition 870250099131, dated 10 / 29 / 2025, p. 53 / 86 47 / 67 UPF network element (i.e., a large network UPF or a public network UPF corresponding to the general DN), and the first UPF network element is used to perform packet routing. The SMF network element implements the migration of ULCL routing points based on the location of a terminal device user.

[00142] Furthermore, it should be understood that the above is described primarily from the perspective that both the origin location and the visited location (roaming location) are 5G networks, and the terminal device accesses the visited location via the 5G network. It can be understood that, in some implementations, the terminal device may alternatively access the visited location (roaming location) via 4G (e.g., accessing a public land mobile network (PLMN) at the visited location via a 4G network).When the terminal device performs on-site access via 4G, the first session management function network element (i.e., the first SMF network element prior to the visit) may alternatively be a converged network element of packet data network gateway control plane function and on-site session management, for example, an SMF network element function in a 5G network and a PGW-C function in a 4G network, and may be referred to as an SMF&PGW-C network element, and the first user plane function network element (e.g., the first UPF network element prior to the visit) may be a converged network element of user plane function and packet data network gateway function, for example, a UPF network element function in a 5G network and a PGW-U function in a 4G network, and may be referred to as a UPF&PGW-U network element.

[00143] In one possible implementation, a mobility management entity (MME) in Petition 870250099131, dated 10 / 29 / 2025, page 54 / 86 48 / 67 visited location can select the SMF&PGW-C network element for the terminal device to access when the accessed terminal device subscribes to a dedicated 5G DN (e.g., the first dedicated DN).

[00144] Furthermore, when the terminal device accesses the visited location (the roaming location) via 4G, the UPF&PGW-U network element can also perform 4G and 5G packet format conversion in a packet transmitted between the first dedicated DN and the terminal device, to support packet transmission between the first dedicated DN and the terminal device.

[00145] For example, the packet transmitted between the first dedicated DN and the terminal device is a GTP-U packet. Since the terminal device accesses the visited location via 4G, a packet sent by the terminal device to the first dedicated DN is a 4G GTP-U packet. After receiving the 4G GTP-U packet, the UPF&PGW-U network element can convert the packet into a 5G GTP-U packet, for example, by adding a field required for a 5G GTP-U packet, such as a QoS flow identifier, to the header of the 4G GTP-U packet, and send the 5G GTP-U packet to the first dedicated DN after converting the 4G GTP-U packet into a 5G GTP-U packet. Similarly, a packet sent by the first dedicated DN to the terminal device is a 5G GTP-U packet.After receiving the 5G GTP-U packet, the UPF&PGW-U network element can convert the packet into a 4G GTP-U packet, for example, by deleting a field that is only required for the 5G GTP-U packet, such as the QoS flow identifier from a 5G GTP-U packet header, and then send the 4G GTP-U packet to the terminal device after converting the 5G GTP-U packet into the 4G GTP-U packet.

[00146] Furthermore, it can be understood that, in this modality of the present application, the first network element of function of Petition 870250099131, dated 10 / 29 / 2025, page 55 / 86 49 / 67 session management can be not only the SMF&PGW-C network element, but also an SMF&PGW network element or an SMF&PGW-C&PGW-U network element. In other words, when the terminal device accesses the visited location via 4G, the first session management function network element can have not only the SMF network element function and the PGW-C function, but also the PGW-U function. The fact that the first session management function network element is the SMF&PGW-C network element is merely an example and does not constitute a limitation of this application.

[00147] Similarly, the first user plane function network element may be not only the UPF&PGW-U network element, but also a UPF&PGW network element, or a UPF&PGW-C&PGW-U network element. In other words, when the terminal device accesses the visited location via 4G, the first user plane function network element may not only have the UPF network element function and the PGW-U function in the 5G network, but also have the PGW-C function. The fact that the first user plane function network element is the UPF&PGW-U network element is merely an example and does not constitute a limitation of this application.

[00148] The following describes a communication method provided in an embodiment of this application, using an example where a terminal device accesses a roaming location (or a visited location) via 4G, a first session management function network element (i.e., the first prior SMF network element) is a UPF&PGW-U network element, a first user plane function network element (i.e., the first prior UPF network element) is a UPF&PGW-U network element, a first dedicated DN is a campus DN, a public DN is the internet, and the terminal device accesses a campus DN at a terminal device source location in the roaming location. The method may include Petition 870250099131, dated 10 / 29 / 2025, p. 56 / 86 50 / 67 the following steps.

[00149] S1201: An MME network element selects an SMF&PGW-C network element (i.e., the first SMF network element) based on the user subscription information of the terminal device.

[00150] In this embodiment of the present application, a UDM network element or a UDM&HSS network element (a converged UDM and HSS network element or device) may retain the user subscription information of the terminal device, and the user subscription information of the terminal device may include information about a dedicated 5G DN (e.g., the first dedicated DN) to which the terminal device subscribes. When the terminal device performs access at the visited location via 4G, the MME network element at the visited location may select, for the terminal device to access when the user subscribes to the dedicated 5G DN, the network element of SMF&PGW-C, which functions as a 5G network element. SMF regarding the function of a 4G PGW-C network element, and the UPF&PGW-U, which functions as a 5G network element. UPF regarding the function of a 4G PGW-U network element.

[00151] S1202: A PCF network element sends the first information to the SMF&PGW-C network element (i.e., the first SMF network element) at the roaming location.

[00152] The initial information may include an identifier of a campus DN to which the terminal device subscribes (e.g., a campus DN DNN) and a list of IP addresses and / or a list of domain names that correspond / match the campus DN.

[00153] In one example, when the terminal device performs the access, the SMF&PGW-C network element can initiate a session management policy association establishment / modification procedure with the PCF network element, and the PCF network element can deliver to the element of Petition 870250099131, dated 10 / 29 / 2025, page 57 / 86 51 / 67 SMF&PGW-C network, in the session management policy association establishment / modification procedure, the first information, including information such as an identifier of the dedicated DN to which the terminal device subscribes and a traffic routing policy for a packet (or traffic) from the terminal device. Alternatively, the PCF network element may actively deliver the first information to the SMF&PGW-C network element upon identifying that the terminal device's user subscription information changes (e.g., a service subscribed to by the terminal device changes from a public network service to a public network service and a first dedicated network service) and the user establishes a session.

[00154] S1203: The SMF&PGW-C network element (i.e., the first SMF network element) at the roaming location sends a first activation request to a second SMF network element at the home location, where the first activation request carries the campus DN identifier.

[00155] It should be understood that the SMF&PGWC network element supports 4G / 5G parameter mapping via an N16a interface. When the terminal device accesses the roaming location via 4G, the SMF&PGW-C network element can map a 4G parameter from the terminal device to a 5G parameter in order to establish a terminal device session with the dedicated DN (e.g., the first dedicated DN). For example, if the number of bits in the tracking area identity (TAI) of the terminal device in 4G is less than in 5G, 0 can be added to the terminal device's TAI in 4G to obtain the TAI in 5G, in order to ensure the correctness of the TAI format in the dedicated DN (e.g., the first dedicated DN). Additionally, an NF Instance ID or an IP address of the SMF&PGW-C can be Petition 870250099131, dated 10 / 29 / 2025, p. 58 / 86 52 / 67 is used as an AMF instance identifier (AMF instance ID), and a 5G RAT NR value is used for radio access technology. These parameters can be sent to the second SMF network element using the first activation request, or they can be sent to the second SMF network element using another message or signaling, to establish the terminal device session. This is not limited to this request.

[00156] S1204: The second SMF network element at the initial location selects a second UPF network element for the campus DN based on the campus DN identifier.

[00157] Furthermore, the first activation request may still carry the first tunnel information from the UPF&GW-U network element (i.e., the first UPF network element), and the second SMF network element at the initial location may still send the first tunnel information to the second UPF network element, so that the second UPF network element establishes a downlink tunnel to the UPF&GW-U network element (i.e., the first UPF network element).

[00158] S1205: The second SMF network element at the initial location sends a first activation response to the SMF&PGW-C network element at the roaming location (i.e., the first SMF network element), where the activation response ports second tunnel information from the second UPF network element.

[00159] S1206: The SMF&PGW-C network element (i.e., the first SMF network element) at the roaming location sends second information to the UPF&GW-U network element (i.e., the first UPF network element), where the second information includes second tunnel information and a first traffic routing rule.

[00160] The first traffic routing rule indicates the sending, to the second UPF network element, of a packet destined for the campus DN and sent by the terminal device. The Petition 870250099131, dated 10 / 29 / 2025, page 59 / 86 The 53 / 67 UPF&GW-U network element (i.e., the first UPF network element) can establish an uplink tunnel to the second UPF network element based on the second tunnel information and can forward, according to the first traffic routing rule, a packet destined for the campus DN and originating from the terminal device, and a packet destined for the internet and originating from the terminal device. For example, the packet destined for the campus DN and originating from the terminal device is sent to the second UPF network element through the uplink tunnel established between the second UPF network element and the UPF&GW-U network element, so that the second UPF network element forwards the packet to the campus DN; and the packet destined for the internet and originating from the terminal device is sent to the internet.

[00161] Furthermore, the UPF&GW-U network element (i.e., the first UPF network element) may also construct a GTPU packet carrying an IP address allocated to the terminal device by the SMF&PGW-C network element (i.e., the first SMF network element), the UPF&GW-U network element (i.e., the first UPF network element), or similar, and send the GTPU packet to the second UPF network element. The second UPF network element associates the terminal device's IP address with a dedicated IP address of the terminal device in the campus DN, to perform address translation and similar in a packet transmitted between the campus DN and the terminal device.

[00162] Furthermore, it should be understood that when the terminal device accesses the visited location (the roaming location) via 4G, the UPF&PGW-U network element can still perform 4G and 5G packet format conversion in a packet transmitted between the first dedicated DN and the terminal device, to support packet transmission between the first dedicated DN. Petition 870250099131, dated 10 / 29 / 2025, pp. 60 / 86 54 / 67 and the terminal device.

[00163] For an implementation of the communication method shown in Figure 12, see the descriptions of the communication method shown in Figure 5 or Figure 9. Details are not described again.

[00164] It can be understood that, to implement the functions in the preceding embodiments, the first session management network element, the second session management network element, the first user plane function network element, and the second user plane function network element include corresponding hardware structures and / or software modules to perform the functions. A person skilled in the art should be aware that, in combination with the units and method steps in the examples described in the embodiments disclosed in this application, this application can be implemented using hardware or a combination of computer hardware and software. Whether a function is performed by hardware or by hardware controlled by computer software depends on specific application scenarios and the design constraints of the technical solutions.

[00165] Figures 13 and 14 are diagrams of the structures of possible communication devices according to the embodiments of this application. These communication devices can be configured to implement a function of the first session management network element, the second session management network element, the first user plane function network element, or the second user plane function network element in the previous method embodiments and, therefore, can also implement beneficial effects of the previous method embodiments.

[00166] As shown in Figure 13, the communication device 1300 includes a processing unit 1310 and an interface unit 1320. The interface unit 1320 can, Petition 870250099131, dated 10 / 29 / 2025, pp. 61 / 86 55 / 67 alternatively, be a transceiver unit or an input / output interface. The 1300 communication device can be configured to implement a function of the first communication device or the second communication device in the embodiment of the method shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11 or Figure 12.

[00167] When the communication appliance 1300 is configured to implement the function of the first session management network element in the method mode shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, or Figure 12, the interface unit 1320 is configured to: receive the first information from a policy control network element, wherein the first information includes an identifier of a first dedicated data network to which a terminal device subscribes, and the communication appliance is a session management network element at a visited location of the terminal device; send a first request to a second session management network element, wherein the first request includes the identifier of the first dedicated data network, and the second session management network element is a session management network element that supports the first dedicated data network;and receive a first response from the second session management network element, wherein the first response includes the second tunnel information from a second user plane role network element, and the second user plane role network element is a user plane role network element selected by the second session management network element based on the first dedicated data network; Processing unit 1310 is configured to determine an initial traffic routing rule; and the unit of Petition 870250099131, dated 10 / 29 / 2025, pp. 62 / 86 Interface 56 / 67 1320 is further configured to send second information to a first user plane function network element, where the second information includes the second tunnel information and the first traffic routing rule, the first traffic routing rule instructs the first user plane function network element to send, to the second user plane function network element, a packet that is for the first dedicated data network and that is sent by the terminal device, and the first user plane function network element is a user plane function network element selected for a general data network to which the terminal device subscribes.

[00168] In a possible project, the initial information also includes a list of IP internet protocol addresses and / or a list of domain names that correspond to the first dedicated data network; and the first traffic routing rule includes the list of IP addresses and / or the list of domain names.

[00169] In one possible design, processing unit 1310 is further configured to obtain, via a network repository function network element, information about the second session management network element that supports the first dedicated data network.

[00170] In a possible project, the first request also includes the first tunnel information from the first user plane function network element.

[00171] In one possible project, the first request also includes an IP address of the terminal device.

[00172] In one possible project, the 1320 interface unit is further configured to: when the terminal device is located in a service area of ​​the second user plane function network element, send fourth information to the second user plane function network element, where Petition 870250099131, dated 10 / 29 / 2025, pp. 63 / 86 57 / 67 The fourth information includes the first tunnel information from the first user plane function network element and a second traffic routing rule, and the second traffic routing rule instructs the second user plane function network element to send, to the first user plane function network element, a packet that is not for the first dedicated data network and that is sent by the terminal device; and processing unit 1310 is further configured to: before interface unit 1320 sends the second information to the first user plane function network element, determine that the terminal device exits the service area of ​​the second user plane function network element.

[00173] In a possible project, the second traffic routing rule includes the list of IP addresses and / or the list of domain names that correspond / match the first dedicated data network.

[00174] In one possible design, interface unit 1320 is further configured to send the first tunnel information from the first user plane function network element and a third traffic routing rule to a third user plane function network element, wherein the third traffic routing rule instructs the third user plane function network element to send, to the first user plane function network element, a packet that is not for a second dedicated data network and that is sent by the terminal device, and the third user plane function network element is a user plane function network element selected by processing unit 1310 based on the second dedicated data network.

[00175] In a possible project, the third traffic routing rule includes a list of IP addresses and / or a list of domain names that match / match the Petition 870250099131, dated 10 / 29 / 2025, pp. 64 / 86 58 / 67 second dedicated data network.

[00176] In a possible design, when the terminal device performs access at the visited location via 4G, the first network element of session management function is a converged network element of packet data network gateway control plane function at the visited location, and the first network element of user plane function is a converged network element of user plane function and packet data network gateway function at the visited location.

[00177] When the communication appliance 1300 is configured to implement the first user plane function network element function in the method mode shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, or Figure 12, the interface unit 1320 is configured to receive second tunnel information and a first traffic routing rule from a first session management network element, wherein the first session management network element is a session management network element at a visited location of a terminal device, the communication appliance is a user plane function network element selected for a general data network to which the terminal device subscribes, the second tunnel information is tunnel information from a second user plane function network element selected for a first dedicated data network to which the terminal device subscribes,and the first traffic routing rule indicates sending, to the second user plane function network element, a packet that is for the first dedicated data network and that is sent by the terminal device; and processing unit 1310 is configured to establish an uplink tunnel to the second element, Petition 870250099131, dated 10 / 29 / 2025, pp. 65 / 86 59 / 67 user plane function network based on second tunnel information, where the uplink tunnel is used to transmit a packet sent by the 1320 interface unit to the second user plane function network element.

[00178] In a possible project, the first traffic routing rule includes a list of IP internet protocol addresses and / or a list of domain names that correspond / match the first dedicated data network.

[00179] In one possible design, interface unit 1320 is further configured to: send a first packet from the terminal device to the second user-plane function network element via the uplink tunnel, wherein a first domain name carried in the first packet belongs to the list of domain names; and receive a second packet from the second user-plane function network element, wherein the second packet is a response packet to the first packet; and processing unit 1310 is further configured to associate a source IP address of the second packet with the first domain name.

[00180] In one possible design, the 1320 interface unit is further configured to send a third packet to the second user plane function network element, wherein the third packet includes an IP address of the terminal device.

[00181] In a possible design, when the terminal device performs access at the visited location via 4G, the first network element of session management function is a converged network element of packet data network gateway control plane function and session management at the visited location, and the first network element of user plane function is a converged network element of user plane function and packet data network gateway function at the visited location.

[00182] In a possible project, the processing unit Petition 870250099131, dated 10 / 29 / 2025, pp. 66 / 86 60 / 67 1310 is also configured to perform 4G and 5G packet header format conversion in a packet transmitted between the first dedicated data network and the terminal device.

[00183] When the communication appliance 1300 is configured to implement the second session management network element function in the method mode shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, or Figure 12, the interface unit 1320 is configured to receive a first request from a first session management network element, wherein the first request includes an identifier of a first dedicated data network to which a terminal device subscribes, the first session management network element is a session management network element at a visited location of the terminal device, and the communication appliance is a session management network element that supports the first dedicated data network;Processing unit 1310 is configured to determine a first response, wherein the first response includes second tunnel information from a second user plane function network element, and the second user plane function network element is a user plane function network element selected by processing unit 1310 based on the first dedicated data network; and interface unit 1320 is further configured to send the first response to the first session management network element.

[00184] In one possible design, the first request also includes first tunnel information from a first user plane function network element; and interface unit 1320 is further configured to send third information to the second user plane function network element, wherein the third information includes the first tunnel information. Petition 870250099131, dated 10 / 29 / 2025, pp. 67 / 86 61 / 67

[00185] In one possible project, the first request also includes an Internet Protocol (IP) address of the terminal device, and the third piece of information also includes the IP address of the terminal device.

[00186] In one possible project, the third piece of information also includes a dedicated IP address of the terminal device on the first dedicated data network.

[00187] In one possible design, the 1320 interface unit is further configured to obtain the dedicated IP address from a user data management network element, or to obtain the dedicated IP address from a server corresponding to the first dedicated data network.

[00188] When the communication appliance 1300 is configured to implement the second user plane function network element function in the method mode shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11 or Figure 12, the interface unit 1320 is configured to receive a third packet from a first user plane function network element, wherein the third packet includes an IP internet protocol address of a terminal device, the first user plane function network element is a user plane function network element selected for a general data network to which the terminal device subscribes, and the communication appliance is a user plane function network element selected for a first dedicated data network to which the terminal device subscribes;and processing unit 1310 is configured to associate the terminal device's IP address with a dedicated terminal device IP address on the first dedicated data network, wherein an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation in a packet transmitted between the first network; Petition 870250099131, dated 10 / 29 / 2025, pp. 68 / 86 62 / 67 dedicated data and the terminal device.

[00189] In one possible design, interface unit 1320 is further configured to receive third-party information from a second session management network element, wherein the third-party information includes first-party tunnel information, the first tunnel identifier being a tunnel identifier of the first user-plane function network element, and the second session management network element being a session management network element supporting the first dedicated data network; and processing unit 1310 is further configured to establish a downlink tunnel to the first user-plane function network element based on the first tunnel information, wherein the downlink tunnel is used to transmit a packet sent by interface unit 1320 to the first user-plane function network element.

[00190] In one possible project, the third piece of information also includes the dedicated IP address of the terminal device on the first dedicated data network.

[00191] When the communication device 1300 is configured to implement the second user plane function network element function in the method mode shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, or Figure 12, the interface unit 1320 is configured to receive third information from a second session management network element, wherein the third information includes first tunnel information and an IP internet protocol address of a terminal device, the first tunnel identifier is a tunnel identifier of a first user plane function network element, the first user plane function network element is a user plane function network element. Petition 870250099131, dated 10 / 29 / 2025, pp. 69 / 86 63 / 67 user plane selected for a general data network to which the terminal device subscribes, the communication appliance is a user plane function network element selected for a first dedicated data network to which the terminal device subscribes, and the second session management network element is a session management network element that supports the first dedicated data network; and processing unit 1310 is configured to: establish a downlink tunnel to the first user plane function network element based on the first tunnel information, wherein the downlink tunnel is used to transmit a packet sent by interface unit 1320 to the first user plane function network element;and associate the terminal device's IP address with a dedicated IP address of the terminal device on the first dedicated data network, wherein an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation in a packet transmitted between the first dedicated data network and the terminal device.

[00192] In one possible project, the third piece of information also includes the dedicated IP address of the terminal device on the first dedicated data network.

[00193] As shown in Figure 14, this application further provides a communication apparatus 1400, including a processor 1410, and may also include a communication interface 1420. The processor 1410 and the communication interface 1420 are coupled together. It can be understood that the communication interface 1420 may be a transceiver, an input / output interface, an input interface, an output interface, an interface circuit or the like. Optionally, the communication apparatus 1400 may also include a memory 1430, configured to: store instructions to be executed by Petition 870250099131, dated 10 / 29 / 2025, pp. 70 / 86 64 / 67 processor 1410, store input data required by the processor 1410 to run instructions or store data generated after the processor 1410 executes instructions. Memory 1430 can be a physically independent unit or it can be coupled to the processor 1410, or the processor 1410 includes memory 1430.

[00194] When the communication device 1400 is configured to implement the method shown in Figure 5, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11 or Figure 12, the processor 1410 can be configured to implement a function of the processing unit 1310, and the communication interface 1420 can be configured to implement a function of the interface unit 1320.

[00195] It should be noted that the processor, in some embodiments of this application, may be a central processing unit (CPU) or other general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a logic circuit, a field-programmable gate array (FPGA) or other programmable logic device, a transistorized logic device, a hardware component, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[00196] The method steps in embodiments of this application may be implemented in hardware or in a way that executes software instructions by a processor. The software instructions may include a corresponding software module. The software module may be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, or read-only memory. Petition 870250099131, dated 10 / 29 / 2025, pp. 71 / 86 A 65 / 67 electrically erasable programmable disk, a register, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium well known in the art. For example, a storage medium is coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium. Certainly, the storage medium may alternatively be a component of the processor. The processor and the storage medium may be located in an ASIC. Furthermore, the ASIC may be located in a network device or in a terminal device. Certainly, the processor and the storage medium may alternatively exist in a network device or in a terminal device as discrete components.

[00197] All or part of the foregoing embodiments may be implemented by means of software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer programs or instructions are loaded and executed on a computer, all or part of the procedures or functions in the embodiments of this application are executed. The computer may be a general-purpose computer, a dedicated computer, a computer network, a network device, user equipment, or other programmable apparatus.Computer programs or instructions can be stored on a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer programs or instructions can be transmitted from one network device, terminal, computer, server, or data center to another network device, terminal, computer, etc. Petition 870250099131, dated 10 / 29 / 2025, pp. 72 / 86 66 / 67 server or data center in a wired or wireless manner. The computer-readable storage medium can be any usable medium that can be accessed by a computer, or a data storage device, for example, a server or a data center, integrating one or more usable media. The usable medium can be a magnetic medium, for example, a floppy disk, a hard disk, or a magnetic tape, or it can be an optical medium, for example, a digital video disc, or it can be a semiconductor medium, for example, a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or it can include two types of storage medium: a volatile storage medium and a non-volatile storage medium.

[00198] In various embodiments of this application, unless otherwise indicated or there is a logical conflict, the terms and / or descriptions in different embodiments are consistent and can be mutually referenced, and the technical features in different embodiments can be combined based on an internal logical relationship to form a new embodiment.

[00199] Furthermore, it should be understood that, in the modalities of this application, the word "for example" is used to represent an example, an illustration, or a description. Any design modality or solution described as an example in this application should not be explained as being more preferred or having more advantages than another design modality or solution. Precisely, the word "example" is used to present a concept in a specific way.

[00200] It may be understood that the various numbers in the modalities of this application are used merely for differentiation, in order to facilitate description, and not to limit the scope of the modalities of this application. The sequence numbers of the processes above do not signify an execution sequence, and the execution sequence of the processes must be determined based on the functions. Petition 870250099131, dated 10 / 29 / 2025, pp. 73-86 67 / 67 and in the internal logic of the processes. Petition 870250099131, dated 10 / 29 / 2025, pp. 74 / 86

Claims

1 / 11 CLAIMS 1. A communication method, characterized in that it comprises: receiving, by a first session management network element, initial information from a policy control network element, wherein the initial information comprises an identifier of a first dedicated data network to which a terminal device subscribes, and the first session management network element is a session management network element at a visited location of the terminal device; sending, by the first session management network element, a first request to a second session management network element, wherein the first request comprises the identifier of the first dedicated data network, and the second session management network element is a session management network element that supports the first dedicated data network;to receive, by the first session management network element, a first response from the second session management network element, wherein the first response comprises second tunnel information from a second user plane role network element, and the second user plane role network element is a user plane role network element selected by the second session management network element based on the first dedicated data network;and send, through the first session management network element, second information to a first user plane function network element, wherein the second information comprises the second tunnel information and a first traffic routing rule, the first traffic routing rule instructs the first user plane function network element to send, to the second user plane function network element, a packet that is for the first dedicated data network and that is sent by the terminal device, and the first user plane function network element is a user plane function network element selected for a general data network to which the terminal device subscribes.

2. Method, according to claim 1, characterized in that the first information further comprises a list of IP Internet Protocol addresses and / or a list of domain names that correspond to the first dedicated data network; and the first traffic routing rule comprises the list of IP addresses and / or the list of domain names.

3. A method according to claim 1 or 2, characterized in that the method further comprises: obtaining, by means of a network element functioning as a network repository, information about the second network element supporting the first dedicated data network.

4. A method, according to any one of claims 1 to 3, characterized in that the first request also includes first tunnel information from the first user plane function network element.

5. Method according to claim 4, characterized in that the first request also includes an IP address of the terminal device.

6. Method, according to any one of claims 1 to 5, characterized in that the method further comprises: when the terminal device is located in a service area of ​​the second user plane function network element, sending, by the first session management network element, fourth information to the second network element of Petition 870250084585, dated 09 / 19 / 2025, p.30 / 51 3 / 11 user plane function, wherein the fourth information comprises the first tunnel information from the first user plane function network element and a second traffic routing rule, and the second traffic routing rule instructs the second user plane function network element to send, to the first user plane function network element, a packet that is not for the first dedicated data network and that is sent by the terminal device; and before sending, by the first session management network element, the second information to the first user plane function network element, the method further comprises: determining, by the first session management network element, that the terminal device moves out of the service area of ​​the second user plane function network element.

7. Method, according to claim 6, characterized in that the second traffic routing rule comprises the list of IP addresses and / or the list of domain names that correspond to the first dedicated data network.

8. A method, according to any one of claims 1 to 5, characterized in that the method further comprises: sending, by the first session management network element, the first tunnel information from the first user plane function network element and a third traffic routing rule to a third user plane function network element, wherein the third traffic routing rule instructs the third user plane function network element to send, to the first user plane function network element, a packet that is not for a second dedicated data network and that is sent by the terminal device, and the third user plane function network element is a user plane function network element selected by the first session management network element based on the second dedicated data network.

9. Method according to claim 8, characterized in that the third traffic routing rule comprises a list of IP addresses and / or a list of domain names that correspond to the second dedicated data network.

10. A method, according to any one of claims 1 to 9, characterized in that when the terminal device accesses the visited location via 4G, the first session management network element is a converged network element of packet data network gateway control plane function and session management at the visited location, and the first user plane function network element is a converged network element of packet data network gateway data plane function and user plane function at the visited location.

11. A communication method characterized in that it comprises: receiving, by a first user-plane function network element, second tunnel information and a first traffic routing rule from a first session management network element, wherein the first session management network element is a session management network element at a visited location of a terminal device, the first user-plane function network element is a user-plane function network element selected for a general data network to which the terminal device subscribes, the second tunnel information is tunnel information from a second user-plane function network element selected for a first data network. Petition 870250084585, dated 09 / 19 / 2025, p.32 / 51 5 / 11 dedicated to which the terminal device subscribes, and the first traffic routing rule indicates sending, to the second user plane function network element, a packet that is for the first dedicated data network and that is sent by the terminal device; and establishing, by the first user plane function network element, an uplink tunnel to the second user plane function network element based on the second tunnel information, where the uplink tunnel is used to transmit a packet sent by the first user plane function network element to the second user plane function network element.

12. Method, according to claim 11, characterized in that the first traffic routing rule comprises a list of IP internet protocol addresses and / or a list of domain names that correspond to the first dedicated data network.

13. A method according to claim 12, characterized in that when the first traffic routing rule comprises the domain name list corresponding to the first dedicated data network, the method further comprises: sending, through the first user-plane function network element, a first packet from the terminal device to the second user-plane function network element via the uplink tunnel, wherein a first domain name carried in the first packet belongs to the domain name list; receiving, through the first user-plane function network element, a second packet from the second user-plane function network element, wherein the second packet is a response packet to the first packet; and associating, through the first user-plane function network element, a source IP address of the second packet with the first domain name. Petition 870250084585, dated 09 / 19 / 2025, pp. 33 / 51 6 / 11 14. A method according to any one of claims 11 to 13, characterized in that the method further comprises: sending, through the first user-plane function network element, a third packet to the second user-plane function network element, wherein the third packet comprises an IP address of the terminal device.

15. A method, according to any one of claims 11 to 14, characterized in that when the terminal device performs access at the visited location via 4G, the first network element of the session management function is a converged network element of the packet data network gateway control plane function and session management at the visited location, and the first network element of the user plane function is a converged network element of the packet data network gateway data plane function and user plane function at the visited location.

16. Method according to claim 15, characterized in that the method further comprises: performing, by the first user plane function network element, 4G and 5G packet format conversion in a packet transmitted between the first dedicated data network and the terminal device.

17. A communication method characterized in that it comprises: receiving, by a second session management network element, a first request from a first session management network element, wherein the first request comprises an identifier of a first dedicated data network to which a terminal device subscribes, the first session management network element being a session management network element at a visited location of the terminal device, and the second session management network element being a session management network element. Petition 870250084585, dated 09 / 19 / 2025, p.34 / 51 7 / 11 session that supports the first dedicated data network; and send, by the second session management network element, a first response to the first session management network element, wherein the first response comprises second tunnel information from a second user plane function network element, and the second user plane function network element is a user plane function network element selected by the second session management network element based on the first dedicated data network.

18. A method according to claim 17, characterized in that the first request further comprises first tunnel information from the first user plane function network element; and the method further comprises: sending, via the second session management network element, third information to the second user plane function network element, wherein the third information comprises the first tunnel information.

19. Method according to claim 18, characterized in that the first request further includes an Internet Protocol (IP) address of the terminal device, and the third request further includes the IP address of the terminal device.

20. Method according to claim 18 or 19, characterized in that the third information further comprises a dedicated IP address of the terminal device on the first dedicated data network.

21. Method according to claim 20, characterized in that the method further comprises: obtaining, by the second session management network element, the dedicated IP address from a user data management network element, or obtaining the dedicated IP address from a server corresponding to the first dedicated data network.

22. A communication method characterized in that it comprises: receiving, by a second user-plane function network element, a third packet from a first user-plane function network element, wherein the third packet comprises an IP internet protocol address of a terminal device, the first user-plane function network element being a user-plane function network element selected for a general data network to which the terminal device subscribes, and the second user-plane function network element being a user-plane function network element selected for a first dedicated data network to which the terminal device subscribes;and associate, through the second user plane function network element, the terminal device's IP address with a dedicated terminal device IP address on the first dedicated data network, wherein an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation in a packet transmitted between the first dedicated data network and the terminal device.

23. Method according to claim 22, characterized in that the method further comprises: receiving, by the second user plane function network element, third information from a second session management network element, wherein the third information comprises first tunnel information, the first tunnel information being a tunnel identifier of the first user plane function network element, and the second session management network element being a session management network element that supports the first dedicated data network; and establishing, by the second user plane function network element...36 / 51 9 / 11 user, a downlink tunnel to the first user plane function network element based on the first tunnel information, where the downlink tunnel is used to transmit a packet sent by the second user plane function network element to the first user plane function network element.

24. Method according to claim 23, characterized in that the third information further comprises the dedicated IP address of the terminal device on the first dedicated data network.

25. A communication method characterized in that it comprises: receiving, by a second user-plane function network element, third-party information from a second session management network element, wherein the third-party information comprises first-party tunnel information and an IP internet protocol address of a terminal device, the first-party tunnel identifier being a tunnel identifier of a first user-plane function network element, the first user-plane function network element being a user-plane function network element selected for a general data network to which the terminal device subscribes, the second user-plane function network element being a user-plane function network element selected for a first dedicated data network to which the terminal device subscribes,and the second session management network element is a session management network element that supports the first dedicated data network; and establish, by the second user plane function network element, a downlink tunnel to the first user plane function network element based on the first tunnel information, wherein the downlink tunnel is used to transmit a packet sent by the second user plane function network element to the first user plane function network element; and associate the terminal device's IP address with a dedicated terminal device IP address on the first dedicated data network, wherein an association relationship between the terminal device's IP address and the dedicated IP address is used to perform address translation on a packet transmitted between the first dedicated data network and the terminal device.

26. Method according to claim 25, characterized in that the third piece of information further includes the dedicated IP address of the terminal device on the first dedicated data network.

27. Communication apparatus, comprising an interface unit and a processing unit, characterized in that the interface unit is configured to receive and send data; and the processing unit is configured to perform, through the interface unit, the method as defined in any one of claims 1 to 26.

28. Computer-readable storage medium, characterized in that the storage medium stores a computer program or instructions, and, when the computer program or instructions are executed by a processor, the method as defined in any one of claims 1 to 26 is implemented.

29. Communication system, characterized in that the communication system comprises a first session management network element and a first user plane function network element, the first session management network element is configured to perform the method as defined in any one of claims 1 to 10, and the first user plane function network element is configured to perform the method as defined in any one of claims 11 to 16.

30. Communication system according to claim 32, characterized in that it further comprises a second session management network element, wherein the second session management network element is configured to perform the method as defined in any one of claims 17 to 21. Petition 870250084585, dated 09 / 19 / 2025, pp. 39 / 51

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