Communication method and device

Abstract

The invention relates to the technical field of communication, in particular to a communication method and device, which are used for preventing IP addresses of a plurality of special data networks accessed by terminal equipment from conflicting. The method comprises: a control plane network element determines that a service of a first dedicated data network exists in a terminal device; the control plane network element sends first indication information to a first anchor point user plane function network element corresponding to the first special data network to indicate to execute network address translation, the network conversion can be used for converting an IPv6 address of a first private data network carried by a message sent to the first private data network by the terminal equipment into an IPv4 address of the first private data network; and converting the IPv4 address of the first special data network recorded by the message sent by the first special data network to the terminal equipment into the IPv6 address of the first special data network.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0002] Currently, fourth-generation (4G) and fifth-generation (5G) communication systems support user plane function (UPF) network elements that distribute user packets to different session anchors (such as packet data unit (PDU) session anchors), enabling users to access different data networks simultaneously. For example, users can access private data networks such as those of enterprises and public data networks such as the Internet.

[0003] However, the Internet Protocol (IP) addresses of private data networks are typically Internet Protocol version 4 (IPv4) addresses and are planned by the private data networks themselves. If a user wants to access multiple private data networks simultaneously, the IP addresses of the multiple private data networks may conflict, resulting in the inability to correctly distribute user packets to each private data network. Summary of the Invention

[0004] Embodiments of the present application provide a communication method and apparatus for avoiding conflicts in IP addresses of multiple private data networks accessed by a user.

[0005] In a first aspect, an embodiment of the present application provides a communication method, the method comprising: a control plane network element determining that a terminal device has a service of a first dedicated data network; the control plane network element sending a first indication message to a first anchor user plane function network element corresponding to the first dedicated data network, the first indication message instructing the first anchor user plane function network element to perform network address translation, the network address translation being used to convert an Internet Protocol version 6 (IPv6) address of the first dedicated data network carried in a message sent by the terminal device to the first dedicated data network into an IPv4 address of the first dedicated data network, and / or converting the IPv4 address of the first dedicated data network carried in a message sent by the first dedicated data network to the terminal device into an IPv6 address of the first dedicated data network.

[0006] Network address translation can also be used to convert the IPv6 address of the terminal device carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the terminal device, and / or, convert the IPv4 address of the terminal device carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the terminal device.

[0007] Through the above method, the anchor user plane functional network element of the dedicated data network (such as the first dedicated data network) can perform network address translation (such as network address translation 64 (NAT64)) according to the instructions of the control plane network element, so that the IPv4 address of the dedicated data network appears to the terminal device and the diversion user plane functional network element responsible for diversion as an IPv6 address with a corresponding larger number of bits, thereby avoiding conflicts among the IP addresses of multiple dedicated data networks accessed by the terminal device (i.e., the user).

[0008] In one possible design, different IPv6 address prefixes can be planned for different private data networks, and the IPv4 address and IPv6 address of any private data network can be converted according to the IPv6 address prefix corresponding to the private data network.

[0009] As an example: the IPv4 address of the first private data network can be converted into the IPv6 address of the first private data network by adding the IPv6 address prefix corresponding to the first private data network to the IPv4 address of the first private data network, or the IPv6 address of the first private data network can be converted into the IPv4 address of the first private data network by deleting the IPv6 address prefix in the IPv6 address of the first private data network.

[0010] Through the above design, different IPv6 address prefixes can be planned for different private data networks to avoid conflicts between the IPv6 addresses of different private data networks.

[0011] In one possible design, the method also includes: the control plane network element sends a first diversion rule to the diversion user plane functional network element, and the first diversion rule instructs the diversion user plane functional network element to divert the message sent by the terminal device to the first dedicated data network to the first anchor user plane functional network element according to the IPv6 address of the first dedicated data network.

[0012] The control plane network element may be a policy control network element or a session management network element. As an example: in the policy control network element, a diversion rule 1 corresponding to the IPv4 address of the first dedicated data network and a diversion rule 2 corresponding to the IPv6 address of the first dedicated data network may be configured for the first dedicated data network, and the first control policy sent by the policy control function network element may include diversion rule 1 and diversion rule 2; or it may be determined whether to carry diversion rule 1 or diversion rule 2 in the sent first control policy according to whether the first anchor user plane function network element is instructed to perform network address translation. In the case that the first control policy sent by the policy control function network element includes diversion rule 1 and diversion rule 2, the session management function network element may send the first diversion policy to the diversion user plane function network element according to whether the first anchor user plane function network element is instructed to perform network address translation. For example, when instructing the first anchor user plane functional network element to perform network address translation, the session management functional network element can delete diversion rule 1 and only send diversion rule 2 to the diversion user plane functional network element; or send diversion rule 1 and diversion rule 2 to the first anchor user plane functional network element, but instruct the diversion user plane functional network element to use diversion rule 2, etc.

[0013] Through the above design, the control plane network element can send the diversion rules corresponding to the IPv6 address of the first dedicated data network to the diversion user plane function network element for the first dedicated data network that needs to perform network address translation, so as to achieve the effect of only diverting the messages recording the IPv6 address of the first dedicated data network to the first dedicated data network.

[0014] In one possible design, before the control plane network element sends the first indication information to the first anchor user plane function network element corresponding to the first dedicated data network, the method also includes: the control plane network element determines that the terminal device has at least one second dedicated data network service in addition to the first dedicated network service.

[0015] Among them, the first private data network and at least one second private data network can be the visited private data network of the terminal device; or, the first private data network and at least one second private data network can be the home private data network of the terminal device; or, the first private data network can be the visited private data network of the terminal device, and at least one second private data network can be the home private data network of the terminal device; or, the first private data network can be the home private data network of the terminal device, and at least one second private data network can be the visited private data network of the terminal device.

[0016] Through the above design, the control plane network element can instruct the execution of network address translation only when the terminal device has at least one second dedicated data network service in addition to the first dedicated network service (that is, there is a dedicated data network service superposition), which can avoid the resource overhead caused by executing network address translation when the terminal device only has the first dedicated network service (that is, there is no dedicated data network service superposition).

[0017] In one possible design, the control plane network element is a session management network element, and the control plane network element determines that the terminal device has at least one second dedicated data network service in addition to the first dedicated data network service, including: the session management network element determines that in addition to receiving a first control policy corresponding to the first dedicated data network from the policy control network element, it also receives at least one second control policy corresponding to at least one second dedicated data network from the policy control network element.

[0018] The above design can support the session management network element to identify whether a terminal device has service overlays of a dedicated data network.

[0019] In one possible design, the control plane network element is a policy control network element, which determines that the terminal device has services of at least one second dedicated data network in addition to the services of the first dedicated data network, including: the policy control network element determines that the terminal device is signed up for the first dedicated data network and at least one second dedicated network.

[0020] The above design can support the policy control network element to identify whether a terminal device has service overlays of a dedicated data network.

[0021] In one possible design, the first indication information also instructs the first anchor user plane functional network element to perform domain name system (DNS) conversion, where the DNS conversion is used to convert the address type requested in the DNS request message sent by the terminal device to the first dedicated data network from an AAAA record to an A record, and / or to modify the IPv4 address of the A record in the DNS response message sent by the first dedicated data network to the terminal device to an IPv6 address of an AAAA record.

[0022] Through the above design, the first anchor user plane function network element can also be instructed to perform DNS conversion, supporting the terminal device to request the IPv6 address of the first dedicated data network through the domain name when the first anchor user plane function network element performs network address switching.

[0023] In a second aspect, an embodiment of the present application provides a communication method, the method comprising: a first anchor user plane function network element receiving first indication information from a control plane network element, the first indication information instructing the first anchor user plane function network element to perform network address translation, the first anchor user plane function network element being the anchor user plane function network element corresponding to a first dedicated data network; the first anchor user plane function network element translating an IPv6 address of the first dedicated data network carried in a message sent by a terminal device to the first dedicated data network into an IPv4 address of the first dedicated data network, and / or translating an IPv4 address of the first dedicated data network carried in a message sent by the first dedicated data network to the terminal device into an IPv6 address of the first dedicated data network. Optionally, the control plane network element is a session management network element or a policy control network element.

[0024] The first anchor user plane functional network element can also convert the IPv6 address of the terminal device carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the terminal device, and / or convert the IPv4 address of the terminal device carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the terminal device.

[0025] Through the above method, the anchor user plane functional network element of the dedicated data network (such as the first dedicated data network) can perform network address translation (such as NAT64) according to the instructions of the control plane network element, so that the IPv4 address of the dedicated data network appears to the terminal device and the diversion user plane functional network element responsible for diversion as an IPv6 address with a larger number of corresponding bits, thereby avoiding conflicts among the IP addresses of multiple dedicated data networks accessed by the terminal device (i.e., the user).

[0026] In one possible design, the first anchor user plane functional network element performs network address translation based on the IPv4 and IPv6 dual stack addresses of the terminal device and the IPv6 address prefix corresponding to the first dedicated data network.

[0027] Through the above design, network address translation can be performed based on the IPv4 and IPv6 dual-stack addresses of the terminal device without the participation of the NAT address pool, which is conducive to improving the efficiency of network address translation.

[0028] In one possible design, the first indication information also instructs the first anchor user plane functional network element to perform DNS conversion. The method also includes: the first anchor user plane functional network element performs DNS conversion, and the DNS conversion is used to convert the address type requested by the DNS request message sent by the terminal device to the first dedicated data network from AAAA record to A record, and / or modify the IPv4 address of the A record in the DNS response message sent by the first dedicated data network to the terminal device to the IPv6 address of the AAAA record.

[0029] Through the above design, it is possible to support the terminal device requesting the IPv6 address of the first dedicated data network through the domain name when the first anchor user plane function network element performs network address switching.

[0030] In one possible design, the first anchor user plane functional network element discards the DNS request message with the address type of A record sent by the terminal device to the first dedicated data network.

[0031] Through the above design, when the first anchor user plane functional network element performs network address switching, the terminal device can avoid using the DNS request message with an outer IPv6 address to request the IPv4 address of the A record.

[0032] In a third aspect, embodiments of the present application provide a communication device having the functionality to implement the method of the first or second aspect described above. The functionality may be implemented through hardware or through hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the functionality, such as an interface unit and a processing unit.

[0033] In one possible design, the device may be a chip or an integrated circuit.

[0034] In one possible design, the device includes a memory and a processor, the memory is used to store instructions executed by the processor, and when the instructions are executed by the processor, the device can perform the method of the first aspect or the second aspect.

[0035] In a fourth aspect, an embodiment of the present application provides a communication device, comprising an interface circuit and a processor, wherein the processor and the interface circuit are coupled to each other. The processor implements the method of the first or second aspect described above through a logic circuit or executing instructions. The interface circuit is configured to receive signals from other communication devices outside the communication device and transmit them to the processor, or to transmit signals from the processor to other communication devices outside the communication device. It will be understood that the interface circuit may be a transceiver, a transceiver, a transceiver, or an input / output interface.

[0036] Optionally, the communication device may further include a memory for storing instructions executed by the processor, or storing input data required by the processor to execute instructions, or storing data generated after the processor executes instructions. The memory may be a physically independent unit, or may be coupled to the processor, or the processor may include the memory (i.e., the processor and memory are integrated together).

[0037] In a possible implementation, the communication device is a chip.

[0038] In a fifth aspect, an embodiment of the present application provides a communication system, which includes a control plane network element and a first anchor user plane function network element. The control plane network element can implement the method of the first aspect above, and the first anchor user plane function network element can implement the method of the second aspect above.

[0039] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium, in which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, the method of the first or second aspect mentioned above can be implemented.

[0040] In the seventh aspect, an embodiment of the present application further provides a computer program product, including a computer program or instructions, which, when executed by a processor, can implement the method of the first or second aspect above.

[0041] In the eighth aspect, an embodiment of the present application also provides a chip system, which includes a processor and an interface, and the processor is used to call and execute instructions from the interface. When the processor executes the instructions, the method of the above-mentioned first aspect or second aspect can be implemented.

[0042] The technical effects that can be achieved in the third to eighth aspects mentioned above can refer to the technical effects that can be achieved in the first or second aspects mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the communication system architecture provided in an embodiment of the present application;

[0044] Figure 2 A schematic diagram of data diversion provided in an embodiment of the present application;

[0045] Figure 3 This is one of the message diversion diagrams provided in the embodiment of the present application;

[0046] Figure 4 The second schematic diagram of message diversion provided in the embodiment of the present application;

[0047] Figure 5 One of the schematic diagrams of the NAT64+DNS64 message interaction process provided in an embodiment of the present application;

[0048] Figure 6A 、 Figure 6B and Figure 6C Provide a business scenario diagram for the embodiment of this application;

[0049] Figure 7 One of the schematic diagrams of the communication method provided in the embodiment of the present application;

[0050] Figure 8One of the schematic diagrams of the NAT64+DNS64 message interaction process provided in an embodiment of the present application;

[0051] Figure 9A The second schematic diagram of the communication method provided in the embodiment of the present application;

[0052] Figure 9B The third schematic diagram of the communication method provided in the embodiment of the present application;

[0053] Figure 10 Schematic diagram of the communication method provided in the embodiment of the present application;

[0054] Figure 11 The fifth schematic diagram of the communication method provided in the embodiment of the present application;

[0055] Figure 12 Schematic diagram of the communication method provided in the embodiment of the present application;

[0056] Figure 13 Schematic diagram of the communication method provided in the embodiment of the present application;

[0057] Figure 14 This is one of the structural diagrams of the communication device provided in an embodiment of the present application;

[0058] Figure 15 This is a second structural diagram of the communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] The technical solutions of the embodiments of the present application can be applied to various communication systems, for example, they can be applied to communication systems such as the fourth generation (4G) communication system and the fifth generation (5G) communication system, and can also be applied to systems evolved after 5G (such as 6G mobile communication systems), or communication systems that are the integration of two or more of the above systems. The following describes some network architectures to which the present application is applicable. In the following description, the terminal device is taken as user equipment (UE) as an example.

[0060] like Figure 1As shown, it is a schematic diagram of a possible 5G network architecture applicable to the present application, which includes UE, data network (DN) and operator network. The operator network may include one or more of the following network elements (or devices): access network (AN) equipment or radio access network (RAN) equipment, user plane function (UPF) network element, access and mobility management function (AMF) network element, session management function (SMF) network element, policy control function (PCF) network element, application function (AF) network element, network slice selection function (NSSF) network element, authentication server function (AUSF) network element, user data management (UDM) network element, network slice-specific authentication and authorization function (NSSAAF) network element. In the above-mentioned operator network, network elements or devices other than access network devices can be referred to as core network network elements or core network devices. It is important to understand that Figure 1 The network elements / devices involved in the deployment can be one or more.

[0061] Terminal device: The terminal device and access network equipment communicate with each other using an air interface technology. This air interface can be a wireless air interface based on the 5G standard, such as the new radio (NR) air interface; or an air interface based on the next-generation mobile communication network technology standard of 5G; or an air interface based on the 4G standard (such as the Long Term Evolution (LTE) system). The terminal device can be a user equipment (UE), a handheld terminal, a laptop computer, a subscriber unit, a cellular phone, a smart phone, a wireless data card, a personal digital assistant (PDA), a tablet computer, a wireless modem, a handheld device, a laptop computer, a cordless phone, a machine type communication (MTC) terminal, or other device that can access the network.

[0062] Access network equipment: This equipment is primarily responsible for radio resource management, quality of service (QoS) management, data compression, and encryption on the air interface side. Access network equipment can include base stations, pole sites, integrated access and backhaul (IAB) nodes, Node Bs, mobile base stations, evolved NodeBs (eNodeBs), transmission reception points (TRPs), radio access networks (RANs), radio access network equipment, evolved NodeBs (eNodeBs) in LTE systems or evolved LTE-Advanced (LTE-A) systems, next-generation NodeBs (gNBs) in 5G mobile communication systems, and base stations in future mobile communication systems. It can also be a module or unit that performs some of the functions of a base station, such as a centralized unit (CU) or a distributed unit (DU). A RAN device can be a macro base station, a micro base station (also known as a small cell), an indoor base station, a relay node, or a donor node. The embodiments of the present application do not limit the specific technology and specific device form adopted by the access network device.

[0063] In addition, the access network device can also be an untrusted non-3GPP access network device. The untrusted non-3GPP access network device can allow the terminal device and the 3GPP core network to interconnect and communicate using non-3GPP technologies, where non-3GPP technologies include: wireless fidelity (Wi-Fi), worldwide interoperability for microwave access (WiMAX), code division multiple access (CDMA) network, etc. Compared with the trusted non-3GPP access network device, the 3GPP core network can be directly accessed. The network element needs to interconnect and communicate with the 3GPP core network through a secure tunnel established by a security gateway, where the security gateway is, for example, an evolved packet data gateway (ePDG) or a non-3GPP inter working function (N3IWF) network element.

[0064] AMF network element: A core network element, primarily responsible for signaling processing, such as access control, mobility management, attach and detach, and gateway selection. When the AMF network element provides services for a session in a terminal device, it provides control plane storage resources for the session, as well as storage for the session identifier and the SMF network element identifier associated with the session identifier.

[0065] SMF network element: responsible for user plane network element selection, user plane network element redirection, Internet Protocol (IP) address allocation, bearer establishment, modification and release, and QoS control.

[0066] The UPF network element is responsible for forwarding and receiving user data from terminal devices. It receives user data from the data network and transmits it to the terminal device via the access network equipment. The UPF network element also receives user data from the terminal device via the access network equipment and forwards it to the data network. The transmission resources and scheduling functions provided by the UPF network element to the terminal device are managed and controlled by the SMF network element.

[0067] PCF network element: mainly supports providing a unified policy framework to control network behavior, provides policy rules to the control layer network functions, and is responsible for obtaining user contract information related to the policy.

[0068] AUSF network element: mainly provides authentication functions and supports authentication of 3GPP access and Non-3GPP access.

[0069] UDM network element: Main functions include supporting authentication credentials processing in 3GPP authentication and key negotiation mechanisms, user identity processing, access authorization, registration and mobility management, contract management, short message management, etc.

[0070] NSSF network element: The main functions include selecting a group of network slice instances for terminal devices, determining the allowed NSSAI, and determining the set of AMF network elements that can serve terminal devices.

[0071] AF network element: mainly supports interaction with the 3GPP core network to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side.

[0072] The above-mentioned N4 interface is the interface connecting the control plane SMF network element and the user plane UPF network element. The SMF network element can interact with the UPF network element through the N4 interface, and can complete the creation, modification and release of user plane sessions, so that users (ie UE) can access the Internet through the UPF network element.

[0073] The N9 interface is the user plane interface between the intermediate (I)-UPF and the UPF, and is used to transmit uplink and downlink user data flows between UPF network elements. When the anchor UPF network element can cover the user's location, the anchor UPF network element is directly connected to the (R)AN through the N3 interface. When the anchor UPF network element cannot cover the user's location, an I-UPF network element is inserted between the anchor UPF network element and the (R)AN. The I-UPF network element is decoupled from the (R)AN connection through the N3 interface and connected to the anchor UPF network element through the N9 interface. In another possible scenario, when the user needs to divert traffic locally, the UPF network element used for diversion can be connected to the UPF network element of the auxiliary anchor point and the UPF network element of the main anchor point through the N9 interface respectively.

[0074] The N7 interface is the interface between the SMF network element and the PCF network element. The SMF network element can obtain the session policy from the PCF network element through the N7 interface.

[0075] The N16a interface (not shown in the figure) is the interface between the I-SMF and the SMF. When a user roams across provinces (or regions) and accesses from the roaming location, the I-SMF network element in the visited (or roaming) province can connect to the SMF network element in the home province through the N16a interface to transmit session information.

[0076] Figure 1N1, N2, N5, N6, N7, N8, N10, N11, N12, N13, N15, N22, N58, and N59 are interface serial numbers. For example, the meaning of the above interface serial numbers can be found in the definition in the 3rd Generation Partnership Project (3GPP) standard protocol.

[0077] To facilitate understanding by those skilled in the art, some terms used in the embodiments of the present application are explained below.

[0078] 1) Dedicated data network (DN), also known as dedicated data network, private network data network, private network, private network, etc., usually refers to an internal network, which can be the intranet of an enterprise, the intranet of a park, the intranet of a supermarket, etc.

[0079] 2) Universal DN, also known as public network DN, universal DN, public network, large network, etc., usually refers to the Internet, or may refer to the operator's access point or access network to the Internet, such as China Unicom's 3Gnet.

[0080] 3) IP address. The IP addresses in the implementation of this application involve Internet Protocol version 4 (IPv4) addresses and Internet Protocol version 6 (IPv6) addresses. IPv4 addresses consist of 32-bit binary digits, usually expressed in dotted decimal notation (e.g., 192.168.1.1), and are divided into four 8-bit fields. Because IPv4 addresses are only 32 bits, theoretically, a maximum of approximately 4.2 billion addresses can be used. However, with the rapid expansion of the Internet, this number can no longer meet the needs of all devices. IPv6 addresses consist of 128-bit binary digits, usually expressed as 8 groups of hexadecimal digits separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The IPv6 address space is very large and can theoretically support approximately 3.4 trillion (3.4×10^38) addresses. This number is several orders of magnitude greater than the number of IPv4 addresses, eliminating address shortages and providing each device with a globally unique address. In some implementations, to enable interoperability between IPv4 and IPv6 addresses, an IPv4 address is embedded within an IPv6 address. In this case, the address is often represented as: X:X:X:X:X:X:dddd, with the first 96 bits in colon-delimited hexadecimal notation and the last 32 bits in dotted decimal notation.

[0081] 4) Anchor UPF network element. In this embodiment of the present application, each UPF network element that can communicate with the DN through the N6 interface can be called an anchor UPF network element, or a UPF network element with anchor function. A UPF network element with anchor function in a session can also be called a session anchor UPF network element.

[0082] 5) Uplink classifier (ULCL) diversion. In 5G, the UPF network element that supports ULCL can divert user messages and support users to access different data networks at the same time. Figure 2 As shown in the message diversion diagram, the ULCL UPF network element can divert user messages to the PDU session anchor (PSA) 2UPF network element (auxiliary anchor UPF) and the PSA1 UPF network element (primary anchor UPF) according to the ULCL rules. Among them, the ULCL UPF network element is a UPF network element that has or supports the ULCL function, and the PSAUPF network element is a UPF network element that supports or has the PSA function. PSA is the PDU session anchor and is the processing point for terminating the general packet radio service (GPRS) tunneling protocol (GTP) tunnel. Only the UPF network element that serves as the PSA or the UPF network element that has the PSA function can use the N6 interface to connect to the DN. The PSA1 UPF and PSA2UPF network elements can respectively provide N6 interfaces for diverting messages to different DNs. The ULCL UPF network element identifies uplink packets (or traffic) according to the diversion rules and decides whether to send the packets to the primary anchor point or the secondary anchor point. Generally, packets matching the diversion rules are sent through the N6 interface of the secondary anchor point to access the local DN, and the remaining packets are sent to the primary anchor point through the N9 GTP tunnel to access the Internet.

[0083] ULCL diversion can support terminal devices to access the dedicated DN of the visited location (such as the campus DN of a certain campus) in the visited location (roaming scenario), access the dedicated DN of the home location in the home location (non-roaming scenario), access the dedicated DN of the home location in the visited location (roaming scenario), access the dedicated DN of the home location and the dedicated DN of the visited location in the visited location (roaming scenario), etc.

[0084] In addition, it can be understood that in the embodiment of the present application, the home place may refer to the account opening area of ​​the terminal device (usually the mobile phone number of the terminal device), and the unit of the home place may be a city, province, etc. The visited place (also called the roaming place) is relative to the home place. For example: the home place of the terminal device is city A, the terminal device leaves city A and moves to city B, and conducts business in city B. City B can be called the visited place (or roaming place) of the terminal device, and the terminal device is roaming; or, the home place of the terminal device is province A, the terminal device leaves province A and moves to province B, and conducts business in province B. Province B can be called the visited place (or roaming place) of the terminal device, and the terminal device is roaming.

[0085] For example, refer to Figure 3 As shown in the packet diversion diagram, a terminal device (ie, a user) can access the visited campus DN after entering the visited campus through the following steps.

[0086] Step 1: The user enters the campus and scans the QR code to sign up for campus services. The PCF network element (or access and mobility (AM)-PCF network element) can use private information elements to issue campus policies to the AMF network element. The issued campus policies may include diversion rules, billing rules, and QoS. Campus policies can be passed to the SMF network element through the AMF network element.

[0087] Step 2: The SMF network element can obtain the campus diversion rules and billing rules from the campus policy issued by the AM-PCF network element.

[0088] Step 3: The SMF network element can send a session management message (such as a packet forwarding control protocol (PFCP) session establishment request or a PFCP session modification request message) to the ULCL UPF network element over the N4 interface. The SMF network element can deliver the diversion rules to the ULCL UPF network element, so that the ULCL UPF network element can divert the message (or traffic) to the primary anchor UPF network element and the secondary anchor UPF network element according to the diversion rules.

[0089] In addition, the SMF network element can send a session management message (such as a PFCP session establishment request or PFCP session modification request message) to the secondary anchor point UPF network element to establish a secondary anchor point session. The ULCL UPF network element can be integrated with the primary anchor point UPF network element or the secondary anchor point UPF network element. Figure 3 The example in which the ULCL UPF network element and the main anchor point UPF network element are integrated is taken.

[0090] Step 4: The SMF network element can send a session management message (such as PFCP session establishment request or PFCP session modification request message) to the primary anchor point UPF network element to establish the primary anchor point session.

[0091] It is understandable that the campus policy issued by the above PCF network element (or AM-PCF network element) is transmitted to the SMF network element through the AMF network element. Figure 1 In the architecture shown, the PCF network element can also send the campus policy to the SMF network element through the N7 interface. The SMF network element can obtain the campus diversion rules from the campus policy sent by the PCF network element and send them to the ULCL UPF network element, so that the ULCL UPF network element can divert the message (or traffic) to the campus DN according to the diversion rules.

[0092] Through the above steps, after the user enters the visited campus, the ULCL UPF network element can divert the message (or traffic) to the primary anchor UPF network element and the secondary anchor UPF network element according to the diversion rules, supporting the user to access the Internet and the campus DN.

[0093] For example, refer to Figure 4 As shown in the packet diversion diagram, the terminal device (ie, the user) can access the home campus DN in the visited location (also called roaming location) through the following steps.

[0094] Step 1: The home SMF network element (such as a private network SMF network element) can register the supported dedicated DN (such as a campus DN) with the NRF network element.

[0095] Step 2: The PCF network element can send the identifier of the dedicated DN of the terminal device (such as the data network name (DNN) of the campus DN) and the diversion rules to the SMF network element in the roaming area. The diversion rules may include the IP address, domain name, identifier or name corresponding to the dedicated DN.

[0096] Step 3: The roaming SMF can create a session for internet services based on the identifier of the universal DN (e.g., internet) (e.g., universal DNN). It can also discover the home SMF network element through the network repository function (NRF) network element based on the identifier of the private DN (the private network SMF network element is used as an example in the figure).

[0097] Step 4: The roaming SMF network element can create a second session based on the identifier of the dedicated DN, construct an activation message created by the N16a interface and send it to the home SMF network element.

[0098] Among them, the activation message can be a DNN activation request, a dedicated DNN activation request, etc. When sending the activation message, the dnn cell can be directly used to carry the identifier of the dedicated DN; the dnn cell can also be used to carry the identifier of the general DN (such as the general DNN), and the selected DNN can be used to carry the identifier of the dedicated DN (such as the dedicated DNN).

[0099] In some implementations, in order to facilitate the sending of downlink messages of the dedicated DN to the terminal device, the activation message may also carry tunnel information of the roaming UPF network element, where the roaming UPF network element may be a UPF network element selected by the roaming SMF network element based on the universal DN subscribed to by the terminal device, and the tunnel information may include the IP address and / or tunnel identifier (such as the tunnel endpoint identifier (TEID)) of the roaming UPF network element.

[0100] Step 5: The home SMF network element selects the private network UPF network element according to the identifier of the dedicated DN.

[0101] In addition, the home SMF network element can also send the tunnel information of the roaming UPF network element to the private network UPF network element, so that the private network UPF network element can establish a downlink tunnel with the roaming UPF network element.

[0102] Step 6: The home SMF network element returns an activation response to the roaming SMF.

[0103] Among them, the activation response can be a DNN activation response, a dedicated DNN activation response, etc., and the activation response can carry the tunnel information of the private network UPF network element, wherein the tunnel information of the private network UPF network element can include the IP address and / or tunnel identifier of the private network UPF network element.

[0104] Step 7: The roaming SMF network element can send the diversion rules to the roaming UPF network element.

[0105] In addition, the roaming SMF network element can also send the tunnel information of the private network UPF network element to the roaming UPF network element, so that the roaming UPF network element can establish an uplink tunnel with the private network UPF network element.

[0106] Among them, the diversion rules can be used to instruct the messages of the dedicated DN (such as campus DN) sent by the terminal device to be sent to the private network UPF network element, and can support domain name diversion and / or IP address diversion.

[0107] In addition, the roaming UPF network element can also support self-learning the IP address corresponding to the domain name and subsequently divert traffic based on the self-learned IP address. That is, it can support learning the correspondence between domain names and IP addresses by parsing the IP address in the DNS response message. When the message corresponding to the IP address is subsequently received, it can support diversion to a dedicated DN (such as the campus DN). It can also support the aggregation of dedicated DN domain names and IP addresses in the diversion rules at the dedicated DN granularity to save memory.

[0108] Through diversion, internet service traffic is exported from the roaming location, and dedicated DN (such as campus DN) services are transferred to the UPF network element of the home network through the UPF network element of the roaming location.

[0109] Step 8: The home UPF network element can learn the IP address of the universal DN (i.e., public network) and the IP address of the dedicated DN (i.e., private network) through data packets, save the relationship between the two, and perform 1:1 IP address conversion. For uplink messages, the public network UE IP address is replaced with the private network UE IP address; for downlink messages, the private network UE IP address is replaced with the public network UE IP. IP address replacement is supported at both the network layer (Layer 3) and the application layer.

[0110] Step 9: After the roaming UPF network element has created the private network session on the network side, it can also actively construct an uplink message and send it to the private network UPF network element. The source IP in the GTPU encapsulation of the message is the IP address assigned to the terminal device by the roaming SMF network element or UPF network element. The private network UPF network element in the home location can associate the IP address of the terminal device with the private IP address of the terminal device in the private DN (such as the campus DN) to perform address translation on the messages transmitted between the private DN and the terminal device. In addition, the message carries a GTPU private extension header to indicate that it is a message constructed by the network side, and the home location UPF network element will discard it.

[0111] 6) NAT64 and DNS64 technology. NAT64 and DNS64 technology can also be called NAT64+DNS64 technology. It was originally designed to solve the problem of mutual access between IPv6 and IPv4 during the development of IPv6 networks. NAT64 is a stateful network address and protocol conversion technology. Generally, it only supports access to IPv4 network resources initiated by users on the IPv6 network side. However, NAT64 also supports manually configured static mapping relationships to achieve intercommunication between IPv6 hosts and IPv4 services. DNS64 mainly cooperates with NAT64 to synthesize the A record (IPv4 address) in the DNS query information into the AAAA record (IPv6 address), and returns the synthesized AAAA record to the user on the IPv6 side. NAT64 generally works in conjunction with DNS64 without the need for any modifications on the IPv6 client or IPv4 server.

[0112] Figure 5 An example of a message interaction process between NAT64 and DNS64 is provided, which may include:

[0113] Step 1: The IPv6 host sends a DNS query to the DNS64 server, requesting the domain name to be resolved. www.ipv6bbs.cn For example.

[0114] Step 2: The DNS64 server triggers a query to the DNS server for the IPv6 address.

[0115] Step 3: If the DNS server can find the IPv6 address, the returned DNS response (DNS response) carries the IPv6 address corresponding to the domain name; if it cannot find the IPv6 address, the IPv6 address in the returned DNS response is empty (emply).

[0116] Step 4: If the DNS64 server cannot be found, the DNS server is triggered again to query the IPv4 address.

[0117] Step 5: The DNS response returned by the DNS server carries the IPv4 address (11.111.11.11) corresponding to the domain name.

[0118] Step 6: The DNS64 server synthesizes the IPv6 address (64:FF9B::11.111.11.11) and returns it to the IPv6 host.

[0119] Step 7: The IPv6 host initiates an IPv6 packet with a destination address of 64:FF9B::11.111.11 and a source address of 2001:1234::1234 (IPv6 host address). Because the NAT64 server advertises the configured IPv6 address prefix (64:FF9B::) within the IPv6 domain, this packet is forwarded to the NAT64 router.

[0120] Step 8: The NAT64 router performs NAT64 address translation, the destination address is translated to 11.111.11.11, and the source address can be translated to the NAT64 router's public IPv4 address: 22.22.22.22, and routed to the IPv4 server within the IPv4 domain.

[0121] Step 9: The IPv4 server returns IPv4 data with a destination address of 22.22.22.22 and a source address of 11.111.11.11.

[0122] Step 10: The NAT64 router converts the destination address to 64:FF9B::11.111.11.11 and the source address to 2001:1234::1234 based on the existing record. The data is sent to the IPv6 host, and the process ends.

[0123] However, the IP addresses of private data networks are often IPv4 addresses and are planned by the private data networks themselves. If a terminal device wants to access multiple private data networks at the same time, the IP addresses of multiple private data networks may conflict, resulting in the inability to correctly divert user messages to each private data network.

[0124] For example, a terminal device (i.e., user) accesses multiple dedicated DNs for a visited location at the same time. Figure 6AIn the service scenario shown, the visited location has two dedicated DN services: a cloud gaming DN and a museum DN. The cloud gaming DN has a wider coverage area, such as a prefecture-level city, while the museum DN has a narrower coverage area, such as the museum's area. Within the museum's area, the terminal device expects to simultaneously access services from the museum DN, the cloud gaming DN, and the internet. The terminal device can dynamically subscribe to services from the museum DN and the cloud gaming DN at the visited location (e.g., the province). Based on the user's subscription, the PCF network element can pass the diversion rules for the museum DN and cloud gaming DN to the SMF network element via the AMF network element. The SMF network element instructs the diversion UPF network element (e.g., a UPF with ULCL functionality) to perform the diversion. The diversion UPF network element diverts packets with the IP address and domain name corresponding to the museum DN to the museum DN according to the diversion rules for the museum service, and diverts packets with the IP address and domain name corresponding to the cloud gaming DN to the cloud gaming DN according to the diversion rules for the cloud gaming DN. However, the IP addresses of the cloud game DN and the museum DN are planned by the two cloud game parks and the museum park respectively, and the planned IP addresses may conflict with each other (the same, recorded in the figure are all IP1). In this case, the diversion UPF network element cannot correctly divert the messages of the museum DN and cloud game DN services based on the IP address.

[0125] For example, a terminal device (i.e., a user) accesses multiple home-specific DNs simultaneously. Figure 6B In the service scenario shown, the home location has two dedicated DN services, corresponding to campus DN1 and campus DN2 respectively. When the terminal device roams within the province and across provinces, it is expected that the user can access campus DN1, campus DN2, and internet services at the same time. The user's campus DN1 and campus DN2 contract information is in the home location PCF (or session management (SM)-PCF). When the session is activated, the PCF network element will pass the diversion rules of the campus DN1 and campus DN2 subscribed by the user to the SMF network element, and the SMF network element will instruct the diversion UPF network element to divert the traffic. The diversion UPF network element diverts the messages with the IP address and domain name corresponding to campus DN1 to campus DN1 according to the diversion rules of campus DN1 and campus DN2, and diverts the messages with the IP address and domain name corresponding to campus DN2 to campus DN2 according to the diversion rules of campus DN2. However, the IP address of campus DN1 and the IP address of campus DN2 are planned by the two campuses respectively, and the planned IP addresses may conflict with each other (the same, recorded in the figure are all IP1). In this case, the diversion UPF network element cannot correctly divert the services of campus DN1 and campus DN2 based on the IP address.

[0126] For example, a terminal device (i.e., user) accesses the dedicated DNs of the visited location and the home location at the same time. Figure 6CIn the service scenario shown, a terminal device subscribes to services on campus DN1 in its home province, roams across provinces to a visited location (e.g., a visited province), and subscribes to services on the visited location's cloud gaming DN. The user is expected to be able to access services on campus DN1, the cloud gaming DN, and the internet simultaneously. The user's service subscription information for campus DN1 is stored in the home location PCF (or SM-PCF) network element, while the service subscription information for the visited location's cloud gaming DN is stored in the visited location PCF (e.g., AM-PCF) network element. When the user goes online, the visited location PCF network element distributes the traffic diversion rules for the user's subscribed cloud gaming DN to the visited location SMF network element via the AMF network element. The home location PCF network element then distributes the traffic diversion rules for the user's subscribed campus DN1 to the visited location SMF. The visited location SMF instructs the diversion UPF network element to perform traffic diversion. The diversion UPF network element diverts packets with the IP address and domain name corresponding to campus DN1 to campus DN1 based on the diversion rules for campus DN1, and diverts packets with the IP address and domain name corresponding to the cloud gaming DN to the cloud gaming DN based on the diversion rules for the cloud gaming DN. However, the IP address of campus DN1 and the IP address of cloud gaming DN are planned by the two parks respectively, and the planned IP addresses may conflict with each other (the same, recorded in the figure are all IP1). In this case, the diversion UPF network element cannot correctly divert the services of campus DN1 and cloud gaming DN according to the IP address.

[0127] It should be understood that in the embodiment of the present application, the diversion UPF network element can be a UPF network element with a diversion function, such as a UPF network element that supports (or specifically) ULCL function, and a UPF network element that supports message diversion according to the issued diversion rules.

[0128] In the above Figures 6A to 6C In the scenario, if traditional destination network address translation (NAT) conversion (i.e., destination network address translation (DNAT)) technology is used to change the IP address (IPv4 address) of the private data network (such as converting a private IP address to a public IP address, etc.), it is also necessary to plan to ensure that the address pools of different private data networks after DNAT conversion do not conflict. However, different private data networks are deployed in different regions (such as cities and provinces), and each region has its own DNAT conversion planning, which makes it difficult to ensure that the address pools after conversion do not conflict.

[0129] In view of this, the present application provides a communication method and apparatus that employs network address translation between IPv4 and IPv6 addresses in the anchor user plane functional network element of a dedicated data network, so that the IPv4 address of the dedicated data network appears as an IPv6 address to terminal devices and the offload user plane functional network element responsible for offloading. Different dedicated data networks can employ different IPv6 prefixes, thereby avoiding conflicts in the IP addresses of multiple dedicated data networks accessed by a terminal device (i.e., a user). The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

[0130] Furthermore, it should be understood that ordinal numbers such as "first" and "second" in the embodiments of the present application are used to distinguish between multiple objects and are not used to define the size, content, sequence, timing, priority, or importance of the multiple objects. For example, "a first dedicated data network" and "a second dedicated data network" do not indicate a difference in priority or importance between the two dedicated data networks.

[0131] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plural" means two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. For example, A / B means: A or B. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0132] It should be understood that in the embodiments of the present application, the user plane function network element can be the above-mentioned UPF network element, or a network element having the above-mentioned UPF network element function in a future communication system such as a 6G system. The session management network element can be the above-mentioned SMF network element, or a network element having the above-mentioned SMF network element function in a future communication system such as a 6G system. Similarly, the policy control network element can be the above-mentioned PCF network element, or a network element having the above-mentioned PCF network element function in a future communication system such as a 6G system. The specific forms of the user plane function network element, session management network element, policy control network element, etc. are not limited in the embodiments of the present application. For ease of explanation, the embodiments of the present application are described by taking the user plane function network element as a UPF network element, the session management network element as an SMF network element, and the policy control network element as a PCF network element as an example.

[0133] Figure 7 This is one of the schematic diagrams of the communication method provided in an embodiment of the present application, the method comprising:

[0134] S701: The control plane network element determines that a terminal device has a service on the first dedicated data network.

[0135] In an embodiment of the present application, the control plane network element may be an SMF network element, a PCF network element, etc. Taking the control plane network element as an example where the PCF network element is a PCF network element, the PCF network element may determine whether the terminal device has services on the first dedicated data network based on whether the terminal device has signed a contract for services on the first dedicated data network. Taking the control plane network element as an example where the SMF network element is a SMF network element, the SMF network element may determine whether the terminal device has services on the first dedicated data network based on whether the first control policy corresponding to the first dedicated data network is received from the PCF network element. The first control policy may include information such as diversion rules and billing policies, and the diversion rules may include an identifier of the first dedicated data network (such as a DNN) and one or more of an IP address or a domain name.

[0136] S702: The control plane network element sends first indication information to the first anchor UPF network element corresponding to the first dedicated data network. Correspondingly, the first anchor UPF network element receives the first indication information.

[0137] S703: The first anchor UPF network element performs network address translation.

[0138] After the control plane network element identifies that the terminal device has services on the first dedicated data network, the control plane network element can send a first indication message to the first anchor point UPF network element corresponding to the first dedicated data network, instructing the first anchor point UPF network element to perform network address translation (such as NAT64). After receiving the first indication message, the first anchor point UPF network element can start to perform network address translation, convert the message carrying IPv6 address sent by the terminal device to the first dedicated data network into a message carrying IPv4 address, and convert the message carrying IPv4 address sent by the first dedicated data network to the terminal device into a message carrying IPv6 address.

[0139] Taking the example of the first UPF network element performing network address translation (such as NAT64) based on the IPv4 and IPv6 dual-stack addresses of the terminal device and the IPv6 address prefix corresponding to the first dedicated data network, after the first anchor UPF network element starts to perform network address translation (such as NAT64), the original source address of the message received by the first anchor UPF network element from the terminal device is the IPv6 address of the terminal device (the IPv6 address in the IPv4 and IPv6 dual-stack addresses of the terminal device), and the destination address is the IPv6 address of the first dedicated data network. The first anchor UPF network element modifies the message, replaces the source address with the IPv4 address (the IPv4 address in the IPv4 and IPv6 dual-stack addresses of the terminal device), deletes the IPv6 address prefix corresponding to the first dedicated data network from the destination address, and modifies it to the real IPv4 address of the first dedicated data network, and sends the modified message to the first dedicated data network. It can be understood that the IPv4 address of the above-mentioned first dedicated data network may refer to the IPv4 address of the business server (server) in the first dedicated data network, the IPv6 address of the first dedicated data network may refer to the IPv6 address converted from the IPv4 address of the business server in the first dedicated data network, and sending a message to the first dedicated data network may refer to sending a message to the business server in the first dedicated data network.

[0140] In some implementations, after the first anchor UPF network element performs network address translation, it can also perform application layer gateway service (ALG) network address translation (NAT ALG), that is, when the application layer of the message from the terminal device carries the source address or destination address of the IP layer, the IP address of the application layer is also modified.

[0141] The first anchor UPF network element receives a message from the first dedicated data network, and then performs reverse conversion, changing the source address of the message from the real IPv4 address of the first dedicated data network to the IPv6 address of the first dedicated data network, and changing the destination address from the IPv4 address of the terminal device to the IPv6 address of the terminal device.

[0142] In some implementations, the first anchor UPF network element can also perform NAT ALG, that is, when the application layer of the message from the first dedicated data network carries the source address or destination address of the IP layer, the IP address of the application layer is also reversely converted.

[0143] Through the above method, the IPv4 address of a dedicated data network (such as the first dedicated data network) can be presented to terminal devices and the offload user plane functional network element responsible for offloading as an IPv6 address with a larger number of corresponding bits, thereby reducing the probability of IP address conflicts between different dedicated data networks. Furthermore, different IPv6 address prefixes can be planned for different dedicated data networks to avoid IP address conflicts between different dedicated networks.

[0144] As an example: the original IP address of the first private data network is IPv4 address A, the original IP address of the second private data network is also IPv4 address A, the IPv4 addresses of the first private data network and the second private network are the same, also IPv4 address A, but the IPv6 address prefix of the first private data network is IPv6 address prefix A, and the IPv6 address prefix of the second private data network is IPv6 address prefix B. After the first anchor UPF network element of the first private data network and the second anchor UPF network element of the second private data network both perform network address translation (such as NAT64), the first private data network appears as IPv6 address A (IPv6 address prefix A + IPv4 address A) to the terminal device and the diversion user plane function network element responsible for diversion, and the second private data network appears as IPv6 address B (IPv6 address prefix B + IPv4 address A) to the terminal device and the diversion user plane function network element responsible for diversion, and the IPv6 addresses presented by the first private data network and the second private data network are distinguished.

[0145] As another example: the original IP address of the first private data network is IPv4 address A, the original IP address of the second private data network is also IPv4 address A, the IPv4 addresses of the first private data network and the second private network are the same, also IPv4 address A, after the first anchor UPF network element of the first private data network performs network address translation (such as NAT64), the first private data network appears to the terminal device and the diversion user plane function network element responsible for diversion as IPv6 address A (IPv6 address prefix A + IPv4 address A), where the IPv6 address prefix A is the IPv6 address prefix of the first private data network, the second anchor UPF network element of the second private data network does not perform network address translation (such as NAT64), the second private data network still presents IPv4 address A to the terminal device and the diversion user plane function network element responsible for diversion, and the IP addresses presented by the first private data network and the second private data network are IPv6 address A and IPv4 address A respectively, which can also be distinguished.

[0146] In some implementations, to reduce resource overhead caused by network address translation, the control plane network element may send first indication information to the first anchor UPF network element corresponding to the first dedicated data network only when it is determined that the terminal device has services on at least one second dedicated data network in addition to the services on the first dedicated network. In other words, if the terminal device only has services on the first dedicated data network, there will be no IP address conflict for the dedicated data network, and there is no need to perform network address translation (such as NAT64) to save resource overhead.

[0147] Taking the control plane network element as an SMF network element as an example, in a possible implementation, the SMF network element can determine that the terminal device has at least one second dedicated data network service in addition to the first dedicated data network service when it receives a first control policy corresponding to the first dedicated data network and at least one second control policy corresponding to at least one second dedicated data network from the PCF network element.

[0148] As an example: the terminal device enters the coverage of the cloud gaming DN (second dedicated data network) of the visited location and signs up for the cloud gaming DN service by scanning a code or other means. The PCF network element can send the control policy of the cloud gaming DN to the AMF network element by sending a policy control update notification request (Npcf_AMPolicyControl_UpdateNotify Request) message to the AMF network element, and the AMF network element sends the control policy of the cloud gaming DN to the SMF network element through a PDU session update context request (Nsmf_PDUSession_UpdateSMContext Request) message. The SMF network element selects or inserts the second anchor point UPF network element corresponding to the cloud gaming DN to establish a session (such as a PDU session) corresponding to the cloud gaming. The terminal device moves into the coverage area of ​​the museum DN (first dedicated data network) at the visited location and signs up for the museum DN service by scanning a QR code or other means. The PCF network element can send the museum DN's control policy to the AMF network element by sending a policy control update notification request (Npcf_AMPolicyControl_UpdateNotify Request) message to the AMF network element, and the AMF network element sends the museum DN's control policy to the SMF network element by sending a PDU session update context request (Nsmf_PDUSession_UpdateSMContextRequest) message or other means. After the SMF network element receives the museum DN's control policy, combined with the previously received cloud game DN's control policy, it can determine that the terminal device has services superimposed on multiple dedicated data networks, and that the terminal device has services on the cloud game DN (second dedicated data network) in addition to the museum DN (first dedicated data network) services.

[0149] Taking the control plane network element as a PCF network element as an example, in one possible implementation, the PCF network element can determine that the terminal device has services of at least one second private data network in addition to the services of the first private data network when it is determined that the terminal device has signed a contract with a first private data network and at least one second private network.

[0150] As an example: the terminal device enters the coverage of the cloud game DN (second dedicated data network) at the visited location, and signs up for the services of the cloud game DN by scanning a code or other means. The PCF network element can send the control policy of the cloud game DN to the SMF network element through the AMF network element, and the SMF network element selects or inserts the second anchor point UPF network element corresponding to the cloud game DN to establish a session (such as a PDU session) corresponding to the cloud game DN. The terminal device moves into the coverage of the museum DN (first dedicated data network) at the visited location, and signs up for the services of the museum DN by scanning a code or other means. After the terminal device signs up for the services of the museum DN, the PCF network element obtains that the terminal device has signed up for the museum DN (first dedicated data network) on the basis of the cloud game DN (second dedicated data network), and can determine that the terminal device also has services on the second dedicated data network in addition to the services on the first dedicated data network.

[0151] In an embodiment of the present application, it can support diversion of messages sent by terminal devices through domain names and / or IP addresses, etc. For any dedicated data network, the control plane network element can send diversion rules corresponding to the dedicated data network to the diversion UPF network element, which is used by the diversion UPF network element to screen (or filter) messages sent by terminal devices to the dedicated data network.

[0152] It can be understood that if the control plane network element instructs the anchor UPF network element corresponding to a certain dedicated data network (such as the first dedicated data network) to perform network address translation (such as NAT64), the diversion rule corresponding to the dedicated data network sent by the control plane network element to the diversion UPF network element (such as the first diversion rule) may only include the IPv6 address (or IPv6 address and domain name) information of the dedicated data network, but not the IPv4 address information of the dedicated data network. That is to say, the diversion UPF network element does not divert the message sent by the terminal device with the destination address as the IPv4 address to the anchor UPF network element of the dedicated data network (such as the first dedicated data network).

[0153] Of course, the diversion rules (such as the first diversion rules) sent to the diversion UPF network element may also only include the domain name information of the dedicated data network. The diversion UPF network element will divert the messages sent by the terminal device corresponding to the domain name of the dedicated data network to the anchor UPF network element of the dedicated data network based on the domain name of the dedicated data network.

[0154] In some implementations, the diversion UPF network element can also learn the IPv6 address corresponding to the domain name of the dedicated data network, and subsequently divert the message sent by the terminal device with the destination address as the IPv6 address to the anchor UPF network element of the dedicated data network (such as the first dedicated data network) based on the self-learned IPv6 address.

[0155] The IPv6 address of the first dedicated data network can be pre-configured in the terminal device, or obtained by the terminal device through the domain name of the first dedicated data network. This application does not limit the method by which the terminal device obtains the IPv6 address of the first dedicated data network.

[0156] In some implementations, in order to ensure that the terminal device can obtain the IPv6 address of the first dedicated data network through the domain name of the first dedicated data network, the first indication information can also instruct the first anchor UPF network element to perform DNS conversion (such as DNS64 conversion).

[0157] In an embodiment of the present application, an IPv6 address prefix can be planned for each private data network. The IPv6 address prefixes corresponding to different private data networks can be different. For example, the IPv6 address prefix planned for the first private data network is FF9B, the IPv6 address of the terminal device is 2001::1234::1234, and the IPv4 address is 10.52.11. Figure 8 The example illustrates the message interaction process of the first dedicated UPF network element performing DNS 64+NAT64, which includes:

[0158] S801: The first anchor UPF network element receives a DNS request message for an AAAA record (a record pointing to an IPv6 address) sent by a terminal device. The source address of the message is the IPv6 address of the terminal device, and the destination address is the DNS server address of the public network (2002::1111::1111).

[0159] In some implementations, in order to avoid the terminal device using a DNS request message with an outer IPv6 address to request the IPv4 address of an A record (a record pointing to an IPv4 address), causing an IPv4 address conflict in the private data network, the first anchor point UPF network element can discard the DNS request message with an address type of A record sent by the terminal device to the first private data network.

[0160] S802: The first anchor UPF network element performs DNS redirection, NAT64, and DNS64.

[0161] The first anchor UPF network element performs DNS redirection on the DNS request message from the terminal device, and redirects the destination address of the DNS request message (such as 2002::1111::1111) to the DNS server of the first private data network ( Figure 8 Taking the campus DNS as an example), the IPv6 address (FF9B::11.11.11.10) of the terminal device is used as the source address, and NAT64 is performed on the DNS request message. The source address (2001::1234::1234) is replaced with the IPv4 address (10.52.11) of the terminal device, and the destination address is replaced with the IPv4 address (11.11.11.10) of the DNS server of the first private data network. DNS64 is executed to modify the AAAA record request of the DNS request message into an A record request, and send it to the DNS server of the first private data network.

[0162] It should be noted that most current terminal devices support dual-stack IPv4 and IPv6 addresses. In the 3GPP protocol, the 3GPP core network element can allocate an IP address to the terminal device when a session is established. Specifically, both an IPv4 address and an IPv6 address can be allocated. When the first anchor UPF network element performs NAT64, it does not require a NAT address pool and instead replaces the source address of the DNS request message with the IPv6 address of the terminal device.

[0163] S803: The first anchor UPF network element receives the DNS response message.

[0164] The DNS response message may include the IPv4 address of the A record of the first private data network.

[0165] S804: The first anchor UPF network element performs DNS64, NAT64 and DNS redirection.

[0166] Specifically, after receiving the DNS request message of the A record, the DNS server of the first dedicated data network can reply to the first anchor UPF network element with a DNS response message including the IPv4 address of the A record of the first dedicated data network. The first anchor UPF network element can execute DNS64 to modify the IPv4 address (10.11.11.11) of the A record of the DNS request message to the IPv6 address (FF9B::10.11.11.11) of the AAAA record; perform DNS64 on the DNS response message. Perform NAT64, replace the destination address (10.52.11) with the IPv6 address of the terminal device (2001::1234::1234), and replace the source address (11.11.11.10) with the corresponding IPv6 address (FF9B::11.11.11.10). Redirect the DNS response message, replacing the source address (FF9B::11.11.11.10) with the public DNS server address (2002::1111::1111).

[0167] S805: The first anchor UPF network element sends a DNS response message to the terminal device.

[0168] S806: The first anchor UPF network element receives a message (such as a service message) from the terminal device with an IPv6 address corresponding to the first dedicated data network.

[0169] S807: The first anchor UPF network element receives a message from the terminal device corresponding to the IPv6 address of the first dedicated data network and performs NAT64.

[0170] The first anchor UPF network element receives a message from the terminal device, the source address of the message is the IPv6 address of the terminal device, and the destination address is the IPv6 address of the first dedicated data network ( Figure 8 Taking the IPv6 address of the server of the first private data network (such as campus server 1) as an example). The first anchor UPF network element modifies the message, replaces the source address with the IPv4 address of the terminal device, deletes the IPv6 address prefix corresponding to the first private data network from the destination address and modifies it to the real IPv4 address of the first private data network, and sends the modified message to the first private network, such as the server of the first private network (campus server 1).

[0171] In some implementations, after the first anchor UPF network element performs network address translation, it can also perform NAT ALG, that is, when the application layer of the message from the terminal device carries the source address or destination address of the IP layer, the IP address of the application layer is also modified.

[0172] S808: The first anchor UPF network element receives a response message corresponding to the IPv4 address of the first dedicated data network and performs NAT64.

[0173] The first anchor UPF network element receives a message from the first dedicated data network, and then performs reverse conversion, changing the source address of the message from the real IPv4 address of the first dedicated data network to the IPv6 address of the first dedicated data network, and changing the destination address from the IPv4 address of the terminal device to the IPv6 address of the terminal device.

[0174] In some implementations, the first anchor UPF network element can also perform NAT ALG, that is, when the application layer of the message from the first dedicated data network carries the source address or destination address of the IP layer, the IP address of the application layer is also reversely converted.

[0175] In an embodiment of the present application, the private data network accessed by the terminal device may be at the terminal device's visited location, such as the first private data network and the second private data network (the second private data network may be one or more) are the terminal device's visited location private data networks; the private data network accessed by the terminal device may also be at the terminal device's home location, such as the first private data network and the second private data network are the terminal device's home location private data networks; of course, the private data network accessed by the terminal device may also be at the terminal device's visited location and home location, such as the first private data network is the terminal device's visited location private data network, the second private data network is the terminal device's home location private data network, or the first private data network is the terminal device's home location private data network, the second private data network is the terminal device's visited location private data network. The following is combined with Figure 9A 、 Figure 9B ,as well as Figure 10-13 Specific embodiment, for the above Figure 7 The following examples are provided for illustration.

[0176] Figure 9A This is the second flow chart of the communication method provided in the embodiment of the present application. Figure 9A In the illustrated embodiment, taking the first dedicated data network as a museum DN, the second dedicated data network as a cloud gaming DN, and the museum DN and the cloud gaming DN as the visited location DNs of the terminal device as an example, the method includes the following steps:

[0177] Step 1: The visited SMF network element receives the session establishment request and establishes a session.

[0178] As an example, the terminal device can send a session establishment request message (such as a PDU session creation session management context request (Nsmf_PDUSession_CreateSMContext Request) message) to the SMF network element of the visited location through the AMF network element of the visited location to request the establishment of a session. During the session establishment process, the SMF network element of the visited location can interact with the PCF network element (or SM-PCM network element) of the terminal device's home location through session establishment request messages (such as a session management policy control creation request (Npcf_SMPolicyControl_Create Request) message) and session proposal response messages (such as a session management policy control creation response (Npcf_SMPolicyControl_Create Response) message). The message sent by the PCF network element of the home location to the SMF network element of the visited location can carry the control policy of the public data network (such as the internet) and / or the control policy of the private data network to which the terminal device has subscribed. Figure 9A In the example, the terminal device does not subscribe to a dedicated data network in the home location, and the PCF network element in the home location does not send the control policy of the dedicated data network to the SMF network element in the visited location.

[0179] The SMF network element at the visited location can establish a session based on the message sent by the PCF network element at the home location. For example, it receives the control policy of the public data network (such as the Internet) (the control policy may include diversion rules (dynamic or static), billing policy, etc.), selects or inserts the main anchor point UPF network element of the public data network, and establishes a session on the public data network.

[0180] Step 2: The terminal device moves into the coverage area of ​​the visited cloud gaming DN and signs up for the cloud gaming DN service. The PCF network element (or AM-PCF network element) in the visited location can send the cloud gaming DN control policy to the AMF network element by sending a policy control update notification request (Npcf_AMPolicyControl_UpdateNotify Request) message to the AMF network element. The AMF network element sends the cloud gaming DN control policy to the visited SMF network element through a session update request message (such as Nsmf_PDUSession_UpdateSMContext Request message). The visited SMF network element selects or inserts the secondary anchor point UPF network element corresponding to the cloud gaming DN.

[0181] The control strategy of the cloud game DN sent by the PCF network element at the visited location may include the diversion rules (dynamic diversion rules or static diversion rules) and billing rules of the cloud game DN, among which the diversion rules of the cloud game DN may include the IPv4 address, domain name and other information of the cloud game. After the SMF network element at the visited location sends the diversion rules of the cloud game DN to the diversion UPF network element, the diversion UPF network element can divert the messages corresponding to the IPv4 address and domain name of the cloud game DN to the auxiliary anchor point UPF network element of the cloud game DN. The auxiliary anchor point UPF network element of the cloud game DN is connected to the server of the cloud game DN, so that the terminal device can access the cloud game DN.

[0182] Step 3: The terminal device moves into the coverage area of ​​the museum DN at the visited location and signs up for the museum DN service by scanning a code or other means. The PCF network element at the visited location can send a policy control update notification request message to the AMF network element to transmit the museum DN control policy to the AMF network element. The AMF network element then sends the museum DN control policy to the SMF network element at the visited location via a session update request message. The SMF network element at the visited location selects or inserts the secondary anchor point UPF network element corresponding to the museum DN to establish a session for the museum DN.

[0183] The SMF network element at the visited location receives the control policy of the cloud game DN before receiving the control policy of the museum DN, and determines that the terminal device has the services of the cloud game DN in addition to the services of the museum DN, and the terminal device has the services of the dedicated DN superimposed.

[0184] Step 4: The terminal device has a dedicated DN service overlay, and the visited SMF network element can send a first indication message to the auxiliary anchor point UPF network element of the museum DN to instruct the auxiliary anchor point UPF network element of the museum DN to execute NAT64 (or NAT64+DNS64).

[0185] For example: the visited SMF network element can send a session modification request message (such as a PFCP session modification request message) to the secondary anchor point UPF network element of the museum DN, and send a first indication information to the secondary anchor point UPF network element of the museum DN, instructing the execution of NAT64 (or NAT64+DNS64), where the first indication information can be carried in the session modification request message.

[0186] Step 5: The visited SMF network element sends the diversion rules to the anchor UPF network element of the museum DN. Correspondingly, the anchor UPF network element of the museum DN receives the diversion rules.

[0187] In one possible implementation, the museum DN's traffic diversion rule configuration can have two different contents, one for terminal devices without multiple dedicated DNs and the other for terminal devices with multiple dedicated DNs. For example: Diversion Rule 1 for terminal devices without multiple dedicated DNs: The diversion filter condition is the museum DN's IPv4 address; Diversion Rule 2 for terminal devices with multiple dedicated DNs: The diversion filter condition is the museum DN's IPv6 address, and packets with IPv4 addresses are not diverted to the museum DN.

[0188] The visited SMF network element recognizes that the terminal device has multiple dedicated DN services superimposed on it, and can send the museum DN's diversion rule 2 to the diversion UPF network element through a session update request message (such as a PFCP session modification request message).

[0189] It can be understood that the above-mentioned diversion rules (such as diversion rule 1 and diversion rule 2) can also include the domain name of the museum DN. The diversion UPF network element can divert the message matching the domain name of the museum DN or the message matching the IPv6 address of the museum DN to the auxiliary anchor point UPF network element of the museum DN, and then divert it to the museum DN.

[0190] Step 6: The UPF network element of the museum's secondary anchor point DN performs NAT64 (or NAT64+DNS64).

[0191] The UPF network element, the auxiliary anchor point of the museum DN, performs NAT64 on messages transmitted between the terminal device and the museum DN. It can also perform DNS64 on DNS messages (such as DNS request messages and DNS response messages) transmitted between the terminal device and the museum DN. Because the terminal may use a DNS request message with an outer IPv6 address to request an A record, the UPF network element, the auxiliary anchor point of the museum DN, can also discard DNS request messages whose address type is an A record when performing NAT64+DNS64.

[0192] It can be understood that the above is that the SMF network element of the visited location identifies whether the terminal device has multiple dedicated DN service superpositions, and the PCF (or AM-PCF) network element of the visited location identifies whether the terminal device has multiple dedicated DN service superpositions, thereby indicating the need to execute NAT64 (or NAT64+DNS64) when issuing the diversion rules of the museum DN. The indication can be transmitted to the SMF network element of the visited location through the AMF network element of the visited location, and then issued by the SMF network element of the visited location to the auxiliary anchor point UPF network element of the museum DN for execution.

[0193] In addition, the PCF (or AM-PCF) network element, AMF network element, SMF network element and diversion UPF network element at the visited location can use predefined rules to transmit the diversion rules of the visited location's dedicated DN, that is, the name of the rule can be transmitted between the interfaces of each network element, and the specific content of the rule (such as the IP address, domain name, or DNS64 / NAT 64 action of the dedicated DN) can be configured on the diversion UPF network element and the auxiliary anchor point UPF network element. Alternatively, private cells can be added between the interfaces of the PCF (or AM-PCF) network element, AMF network element, SMF network element and diversion UPF network element at the visited location to directly transmit and execute DNS64 / NAT64 actions.

[0194] Figure 9A The example used here is to illustrate a situation where a terminal device activates a session outside the coverage of a visited cloud gaming DN (such as a campus) and then moves to the coverage of the cloud gaming DN. It is understandable that the terminal device can also activate a session within the coverage of a visited cloud gaming DN (such as a campus), and the visited SMF network element receives the diversion rules of the cloud gaming DN and the museum DN in the session establishment request. Alternatively, the terminal device can activate a session within the coverage of a museum DN, and the visited SMF network element receives the diversion rules of the cloud gaming DN and the museum DN in the session establishment request.

[0195] In addition, the above-mentioned visited SMF network element and auxiliary anchor UPF network element can use predefined rules (i.e., reuse the information elements defined by the original protocol of the interface) to indicate the auxiliary anchor UPF network element NAT64 (or NAT64+DNS64), or they can indicate the auxiliary anchor UPF network element NAT64 (or NAT64+DNS64) by adding a new private information element to the interface.

[0196] In addition, it is understandable that the PCF network element can send the DN control policy to the SMF network element through the AMF network element, or send the DN control policy to the SMF network element through the N7 interface. In the embodiment of the present application, the way in which the SMF network element obtains the DN control policy from the PCF network element is not limited. For example: Figure 9A The control strategy of the cloud game DN (or the control strategy of the museum DN) shown in the , the PCF network element at the visited location can send the control strategy of the cloud game DN (or the control strategy of the museum DN) to the SMF network element at the visited location through the AMF network element, or can send the control strategy of the cloud game DN (or the control strategy of the museum DN) to the SMF network element at the visited location through the N7 interface. The implementation of the PCF network element at the visited location sending the control strategy of the cloud game DN (or the control strategy of the museum DN) to the SMF network element at the visited location through the N7 interface can be referred to Figure 9B shown.

[0197] Figure 9B This is the third flow chart of the communication method provided in the embodiment of the present application. Figure 9BIn the illustrated embodiment, still taking the first dedicated data network as a museum DN, the second dedicated data network as a cloud gaming DN, and the museum DN and the cloud gaming DN as the visited location DNs of the terminal device as an example, the method includes the following steps:

[0198] Step 1: The visited SMF network element receives the session establishment request and establishes a session.

[0199] As an example, the terminal device can send a session establishment request message (such as a PDU session creation session management context request (Nsmf_PDUSession_CreateSMContext Request) message) to the SMF network element of the visited location through the AMF network element of the visited location to request the establishment of a session. During the session establishment process, the SMF network element of the visited location can interact with the PCF network element (or SM-PCM network element) of the terminal device's home location through session establishment request messages (such as a session management policy control creation request (Npcf_SMPolicyControl_Create Request) message) and session proposal response messages (such as a session management policy control creation response (Npcf_SMPolicyControl_Create Response) message). The message sent by the PCF network element of the home location to the SMF network element of the visited location can carry the control policy of the public data network (such as the internet) and / or the control policy of the private data network to which the terminal device has subscribed. Figure 9B In the example, the terminal device does not subscribe to a dedicated data network in the home location, and the PCF network element in the home location does not send the control policy of the dedicated data network to the SMF network element in the visited location.

[0200] The SMF network element at the visited location can establish a session based on the message sent by the PCF network element at the home location. For example, it receives the control policy of the public data network (such as the Internet) (the control policy may include diversion rules (dynamic or static), billing policy, etc.), selects or inserts the main anchor point UPF network element of the public data network, and establishes a session on the public data network.

[0201] Step 2: The terminal device moves into the coverage area of ​​the visited cloud gaming DN and subscribes to the cloud gaming DN service. The PCF network element (or SM-PCF network element) at the visited location can send a session update request message to the SMF network element at the visited location via the N7 interface, and send the control policy of the cloud gaming DN to the SMF network element at the visited location. The SMF network element at the visited location selects or inserts the secondary anchor UPF network element corresponding to the cloud gaming DN.

[0202] The control strategy of the cloud game DN sent by the PCF network element at the visited location may include the diversion rules (dynamic diversion rules or static diversion rules) and billing rules of the cloud game DN, among which the diversion rules of the cloud game DN may include the IPv4 address, domain name and other information of the cloud game. After the SMF network element at the visited location sends the diversion rules of the cloud game DN to the diversion UPF network element, the diversion UPF network element can divert the messages corresponding to the IPv4 address and domain name of the cloud game DN to the auxiliary anchor point UPF network element of the cloud game DN. The auxiliary anchor point UPF network element of the cloud game DN is connected to the server of the cloud game DN, so that the terminal device can access the cloud game DN.

[0203] Step 3: The terminal device moves into the coverage area of ​​the museum DN at the visited location and signs up for the museum DN service by scanning a QR code. The PCF network element (or SM-PCF network element) at the visited location sends a session update request message to the SMF network element at the visited location via the N7 interface, conveying the museum DN control policy to the SMF network element at the visited location. The SMF network element at the visited location selects or inserts the UPF network element corresponding to the museum DN and establishes a session for the museum DN.

[0204] The SMF network element at the visited location receives the control policy of the cloud game DN before receiving the control policy of the museum DN, and determines that the terminal device has the services of the cloud game DN in addition to the services of the museum DN, and the terminal device has the services of the dedicated DN superimposed.

[0205] Step 4: The terminal device has a dedicated DN service overlay, and the visited SMF network element can send a first indication message to the auxiliary anchor point UPF network element of the museum DN to instruct the auxiliary anchor point UPF network element of the museum DN to execute NAT64 (or NAT64+DNS64).

[0206] For example: the visited SMF network element can send a session modification request message (such as a PFCP session modification request message) to the secondary anchor point UPF network element of the museum DN, and send a first indication information to the secondary anchor point UPF network element of the museum DN, instructing the execution of NAT64 (or NAT64+DNS64), where the first indication information can be carried in the session modification request message.

[0207] Step 5: The visited SMF network element sends the diversion rules to the anchor UPF network element of the museum DN. Correspondingly, the anchor UPF network element of the museum DN receives the diversion rules.

[0208] In one possible implementation, the museum DN's traffic diversion rule configuration can have two different contents, one for terminal devices without multiple dedicated DNs and the other for terminal devices with multiple dedicated DNs. For example: Diversion Rule 1 for terminal devices without multiple dedicated DNs: The diversion filter condition is the museum DN's IPv4 address; Diversion Rule 2 for terminal devices with multiple dedicated DNs: The diversion filter condition is the museum DN's IPv6 address, and packets with IPv4 addresses are not diverted to the museum DN.

[0209] The visited SMF network element recognizes that the terminal device has multiple dedicated DN services superimposed on it, and can send the museum DN's diversion rule 2 to the diversion UPF network element through a session update request message (such as a PFCP session modification request message).

[0210] It can be understood that the above-mentioned diversion rules (such as diversion rule 1 and diversion rule 2) can also include the domain name of the museum DN. The diversion UPF network element can divert the message matching the domain name of the museum DN or the message matching the IPv6 address of the museum DN to the auxiliary anchor point UPF network element of the museum DN, and then divert it to the museum DN.

[0211] Step 6: The UPF network element of the museum's secondary anchor point DN performs NAT64 (or NAT64+DNS64).

[0212] The UPF network element, the auxiliary anchor point of the museum DN, performs NAT64 on messages transmitted between the terminal device and the museum DN. It can also perform DNS64 on DNS messages (such as DNS request messages and DNS response messages) transmitted between the terminal device and the museum DN. Because the terminal may use a DNS request message with an outer IPv6 address to request an A record, the UPF network element, the auxiliary anchor point of the museum DN, can also discard DNS request messages whose address type is an A record when performing NAT64+DNS64.

[0213] and Figure 9A In the example, the control strategy of cloud game DN (or museum DN) is sent by the visited PCF network element (or AM-PCF network element) to the visited SMF network element through the AMF network element. Figure 9B The PCF network element (or SM-PCF network element) can send the cloud game DN control strategy (or museum DN control strategy) to the visited SMF network element through the N7 interface. Figure 9B The implementation of other parts can refer to Figure 9A The implementation of this part will not be described in detail.

[0214] Figure 10This is a fourth flow chart of the communication method provided in the embodiment of the present application. Figure 10 In the illustrated embodiment, the first dedicated data network is campus DN2, the second dedicated data network is campus DN1, campus DN1 and campus DN2 are home DNs of a terminal device, and the PCF network element identifies that a terminal device has service superposition of multiple campus DNs. The method includes the following steps:

[0215] Step 1: The SMF network element receives a session establishment request message (such as the Nsmf_PDUSession_CreateSMContext Request message) from the AMF network element. During the session establishment process, the SMF network element can exchange session establishment request messages and session proposal response messages (such as the Npcf_SMPolicyControl_CreateRequest / Reponse message) with the home PCF network element (or SM-PCM network element). The home PCF network element includes the control policy of the home campus DN1 and campus DN2 in the message sent to the SMF network element, where the control policy may include diversion rules (such as dynamic diversion rules or static diversion rules).

[0216] Step 2: The SMF network element sends the diversion rules of campus DN1 to the diversion UPF network element to establish a private network session corresponding to campus DN1.

[0217] For example: The SMF network element can convert the diversion rules of campus DN1 obtained from the PCF network element into N4 interface messages (such as PFCP Session Modification Request messages) and send them to the diversion UPF network element, and establish a private network session corresponding to campus DN1.

[0218] Step 3: The SMF network element sends the diversion rules of campus DN2 to the diversion UPF network element to establish a private network session corresponding to campus DN2.

[0219] For campus DN2, the PCF network element needs to identify that the terminal device has superimposed campus DN services. The control policy issued includes dynamic diversion rules. The IP address corresponding to campus DN2 only includes IPv6 addresses, not IPv4 addresses. Packets with IPv4 addresses are not allowed to be diverted to campus DN2.

[0220] Step 4: During the establishment of the private network session in campus 2, the SMF network element can send a session establishment request message (such as the Nsmf_PDUSession_Create Request message) to the private network SMF, and the private network SMF sends a private network session establishment request message (such as the Npcf_SMPolicyControl_Create Request message) to the PCF. The PCF network element can integrate the control policy of the user's public network session and the control policy of multiple private DN sessions (such as the control policy of campus DN1 and the control policy of campus DN2), identify the existence of multiple private DN services superimposed on the terminal device, and return a specific predefined rule in the session establishment response message (such as the Npcf_SMPolicyControl_Create Reponse message) to the private network SMF. This predefined rule can instruct the secondary anchor UPF network element (private network UPF network element) of campus DN2 to perform NAT64 (or NAT64+DNS64). When the private network SMF sends the N4 interface session establishment / update request message (such as PFCPSession Establishment / Modification Request message) to the auxiliary anchor point UPF network element (private network UPF network element) of campus DN2, it can convert the specific predefined rules issued by the PCF network element into N4 interface predefined rules and send them to the auxiliary anchor point UPF network element (private network UPF network element) of campus DN2.

[0221] Step 5: The secondary anchor UPF network element of campus DN2 performs NAT64 (or NAT64+DNS64).

[0222] In addition, since the terminal may use a DNS request message with an outer IPv6 address to request an A record, the auxiliary anchor point UPF network element of the campus DN2 can also discard the DNS request message with the requested address type as an A record when performing NAT64+DNS64.

[0223] It can be understood that the above-mentioned PCF network elements, private network AMF network elements, and private network UPF network elements (such as the auxiliary anchor point UPF network element of campus DN2) can use predefined rules (i.e., reuse the information elements defined by the original protocol of the interface) to instruct the private network UPF to execute DNS64+NAT64, or they can instruct the private network UPF to execute DNS 64+NAT64 by adding new private information elements to the interface.

[0224] In addition, the above-mentioned SMF network element can refer to the public network SMF network element corresponding to the public data network (such as the Internet). In some implementations, the private network SMF network element (such as the SMF network element corresponding to the campus DN2) can be the same SMF network element as the public network SMF network element, and the signaling (or message) interaction between the public network SMF network element and the private network SMF network element can be omitted.

[0225] Figure 11 This is a flow chart of the communication method provided in the embodiment of the present application. Figure 11 In the embodiment shown, the first dedicated data network is campus DN2, the second dedicated data network is campus DN1, campus DN1 and campus DN2 are home DNs of the terminal device, and the SMF network element identifies that the terminal device has service superposition of multiple campus DNs as an example. The method includes the following steps:

[0226] Step 1: The SMF network element receives a session establishment request message (such as Nsmf_PDUSession_CreateSMContext Request message) from the AMF network element. During the session establishment process, the SMF network element can exchange session establishment request messages and session proposal response messages (such as Npcf_SMPolicyControl_CreateRequest / Reponse messages) with the home PCF network element (or SM-PCM network element). The home PCF network element includes the control policy of the home campus DN1 and campus DN2 in the message sent to the home SMF network element, where the control policy can include diversion rules (such as dynamic diversion rules or static diversion rules, Figure 11 For campus DN1 and campus DN2, the PCF network element does not identify whether there is service overlap between multiple dedicated DNs. The dynamic traffic diversion rules for campus DN1 and campus DN2 issued by the PCF network element include the campus's IPv4 address and IPv6 address (i.e., the IPv6 address converted from the IPv4 address (4to6 IP address)).

[0227] Step 2: The SMF network element sends the diversion rules of campus DN1 to the diversion UPF network element to establish a private network session corresponding to campus DN1.

[0228] For example: The SMF network element can convert the diversion rules of campus DN1 obtained from the PCF network element into N4 interface messages (such as PFCP Session Modification Request messages) and send them to the diversion UPF network element, and establish a private network session corresponding to campus DN1.

[0229] Step 3: The SMF network element determines that the terminal device has a dedicated DN service overlay.

[0230] In addition to obtaining the diversion rules of campus DN2 from the PCF network element, the SMF network element also obtains the diversion rules of campus DN1 and determines that the terminal device has service superposition of a dedicated DN.

[0231] Step 4: During the establishment of the private network session corresponding to campus DN2, the SMF network element has identified that the terminal device has multiple campus DN services superimposed on it. The session establishment request message sent to the private network SMF can carry private information elements to instruct the private network UPF (the secondary anchor point corresponding to campus DN2) to perform NAT64 (or NAT64+DNS64). The private network SMF network element receives the private network session establishment request and can carry private information elements in the N4 interface session establishment / update request message (PFCP Session Establishment / Modification Request) to the private network UPF network element (the secondary anchor point corresponding to campus DN2) to instruct the private network UPF network element to perform NAT64 (or NAT64+DNS64).

[0232] Step 5: The SMF network element sends the diversion rules of campus DN2 to the diversion UPF network element.

[0233] For example, the SMF network element can convert the diversion rule of campus DN2 obtained from the PCF network element into an N4 interface message (incoming PFCP Session Modification Request message) and send it to the diversion UPF network element. The diversion SMF network element has identified that the terminal device has service superposition of multiple campus DNs. The message can indicate to the diversion UPF network element through a private cell that it is only allowed to divert IPv6 address packets to campus DN2.

[0234] Step 6: The secondary anchor UPF network element of campus DN2 performs NAT64 (or NAT64+DNS64).

[0235] Since the terminal may use a DNS request message with an outer IPv6 address to request an A record, the auxiliary anchor point UPF network element of campus DN2 can also discard the DNS request message with the requested address type as an A record when performing NAT64+DNS64.

[0236] The above-mentioned SMF network element may refer to a public network SMF network element corresponding to a public data network (such as the internet). In some implementations, a private network SMF network element (such as the SMF network element corresponding to campus DN2) may be the same SMF network element as the public network SMF network element, and the signaling (or message) interaction between the public network SMF network element and the private network SMF network element may be omitted.

[0237] Figure 12 This is the sixth flow chart of the communication method provided in the embodiment of the present application. Figure 12 In the illustrated embodiment, taking the first dedicated data network as campus DN2, the second dedicated data network as campus DN1, campus DN1 as the home DN of the terminal device, and campus DN2 as the visited DN of the terminal device as an example, the method includes the following steps:

[0238] Step 1: The visited SMF network element receives a call establishment request message (such as Nsmf_PDUSession_CreateSMContext Request message) from the AMF network element, and recommends exchanging a session establishment request / response message (such as Npcf_SMPolicyControl_Create Request / Response message) with the home PCF network element (or SM-PCF network element) during the session. The terminal device subscribes to the home campus DN1. During the interaction, the home PCF network element sends the control policy of the home campus DN1 to the visited SMF network element. The control policy may include diversion rules (such as dynamic diversion rules or static diversion rules, Figure 12 For campus DN1, the dynamic traffic diversion rule for campus 1DN1 delivered by the PCF network element can include the campus IPv4 address.

[0239] Step 2: The terminal device moves into the coverage area of ​​the visited campus DN2 and subscribes to the services of the campus DN2. The PCF network element (or AM-PCF network element) of the visited site can send a policy control update notification request (Npcf_AMPolicyControl_UpdateNotify Request) message to the AMF network element to send the control policy of the campus DN2 to the AMF network element. The AMF network element sends the control policy of the campus DN2 to the visited SMF network element through a session update request message (such as Nsmf_PDUSession_UpdateSMContext Request message).

[0240] Step 3: The SMF network element at the visited location determines whether the terminal device has a dedicated DN service overlay.

[0241] The visited SMF network element obtains the diversion rules (or control policies) of the campus DN1 before obtaining the diversion rules (or control policies) of the campus DN2 from the PCF network element, and determines that the terminal device has a dedicated DN service superposition.

[0242] Step 4: During the establishment of the private network session corresponding to the campus DN2, the visited SMF network element has identified that the terminal device has multiple campus DN services superimposed on it. In the N4 interface session establishment / update request message (such as the PFCP Session Establishment / Modification Request message) to the private network UPF (the auxiliary anchor point corresponding to the campus DN2), the private network UPF can be instructed to perform NAT64 (or NAT64+DNS64).

[0243] Step 5: The visited SMF network element sends the diversion rules of campus DN2 to the diversion UPF network element.

[0244] In one possible implementation, the diversion rule configuration for campus DN2 can have two different contents, one for terminal devices without multiple dedicated DNs and the other for terminal devices with multiple dedicated DNs. For example: Diversion rule 1 for terminal devices without multiple dedicated DNs: the diversion filter condition is the IPv4 address of campus DN2; diversion rule 2 for terminal devices with multiple dedicated DNs: the diversion filter condition is the IPv6 address of campus DN2, and packets with IPv4 addresses are not diverted to campus DN2.

[0245] The visited SMF network element recognizes that the terminal device has multiple dedicated DN services superimposed, and can send the diversion rule 2 of campus DN2 to the diversion UPF network element through a session update request message (such as a PFCP session modification request message).

[0246] It can be understood that the above-mentioned diversion rules (such as diversion rule 1 and diversion rule 2) can also include the domain name of campus DN2. The diversion UPF network element can divert the message matching the domain name of campus DN2 or the message matching the IPv6 address of campus DN2 to the auxiliary anchor point UPF network element of campus DN2, and then divert it to campus DN2.

[0247] Step 6: The secondary anchor UPF network element of campus DN2 performs NAT64 (or NAT64+DNS64).

[0248] The UPF network element, the secondary anchor point of campus DN2, performs NAT64 on packets transmitted between terminal devices and campus DN2. It can also perform DNS64 on DNS packets (such as DNS request packets and DNS response packets) transmitted between terminal devices and campus DN2. Because terminals may request A records using DNS request packets with outer IPv6 addresses, the UPF network element, the secondary anchor point of campus DN2, can also discard DNS request packets whose address type is A records when performing NAT64+DNS64.

[0249] It can be understood that the above-mentioned visited SMF network element and private network UPF (such as the auxiliary anchor point UPF network element of campus DN2) can use predefined rules (i.e., reuse the information elements defined by the original protocol of the interface) to instruct the private network UPF to execute DNS64 (or DNS64+NAT64), or add new private information elements to the interface to instruct the private network UPF to execute DNS64 (or DNS64+NAT64).

[0250] The above example describes how the visited SMF network element obtains the traffic diversion policy for home campus DN1 from the home PCF network element upon receiving a session establishment request. It is understood that, after the session is established, the terminal device can also subscribe to the services of home campus DN1, and the home PCF network element can notify the visited SMF network element of the traffic diversion policy for home campus DN1 through the notification update process.

[0251] The above description uses the example of the visited-site SMF network element first obtaining the diversion policy for the home-site campus DN1 and then obtaining the diversion policy for the visited-site campus DN2. It is understood that the visited-site SMF network element can also obtain the diversion policies for both the visited-site and home-site campuses DN1 and DN2 at the same time when the session is established. The SMF determines that the terminal device has services overlapping with multiple dedicated DNs and performs the above processing on the visited-site campus DN2.

[0252] Figure 13 This is the seventh flow chart of the communication method provided in the embodiment of the present application. Figure 13 In the illustrated embodiment, taking the first dedicated data network as campus DN2, the second dedicated data network as campus DN1, campus DN2 as the home DN of the terminal device, and campus DN1 as the visited DN of the terminal device as an example, the method includes the following steps:

[0253] Step 1: The visited SMF network element receives a session establishment request message (such as Nsmf_PDUSession_CreateSMContext Request message) from the AMF network element, and exchanges session establishment request / response messages (such as Npcf_SMPolicyControl_Create Request / Response message) with the home PCF network element (SM-PCF network element) during the proposed session. The terminal device does not have a dedicated DN for the home location, and during the interaction, the home PCF network element does not send a control policy with a dedicated DN for the home location to the visited SMF network element.

[0254] Step 2: The terminal device moves into the coverage area of ​​the visited campus DN1 and subscribes to the service of the campus DN1. The PCF network element (or AM-PCF network element) of the visited site can send the control policy of the campus DN1 to the AMF network element by sending a policy control update notification request (Npcf_AMPolicyControl_UpdateNotify Request) message to the AMF network element. The AMF network element sends the control policy of the campus DN1 to the visited SMF network element through a session update request message (such as Nsmf_PDUSession_UpdateSMContext Request message). The visited SMF network element selects or inserts the secondary anchor point UPF network element corresponding to the campus DN1 (in the process of inserting the secondary anchor point UPF network element, the visited SMF network element can interact with the secondary anchor point UPF network element through the PFCP Session Establishment / Modification Request message).

[0255] The control policy for campus DN1 can include diversion rules for campus DN1 (dynamic or static). The visited SMF network element can issue the diversion rules to the diversion UPF (e.g., via a PFCP Session ModificationRequest message). Based on the diversion rules, the diversion UPF network element can divert packets corresponding to the IPv4 address and domain name of campus DN1 to the secondary anchor UPF network element of campus DN1. The secondary anchor UPF network element of campus DN1 is connected to campus DN1. This allows terminal devices to access campus DN1.

[0256] Step 3: The terminal device signs up for the service of home campus DN2. The home PCF network element pushes an update message (such as the Npcf_SMPolicyControl_UpdateNotify Request message) to the traffic diversion SMF, carrying the control policy of home campus DN2. This control policy may include the dynamic traffic diversion rules for campus DN2. The dynamic traffic diversion rules issued by the PCF network element may include the IPv4 address corresponding to campus DN2 (also known as the IPv4 server IP address of campus DN2) and the IPv6 address (also known as the 4to6 address of the campus DN2 server).

[0257] Step 4: The SMF network element at the visited location obtains the diversion rules of the home campus DN2, and combines it with the diversion rules of the visited campus DN1 obtained previously to determine that the terminal device has multiple dedicated data networks superimposed.

[0258] Step 5: The visited SMF network element creates a private network session for the home campus DN2 based on the diversion rules of the home campus DN2. During the private network session establishment process, the visited SMF network element can send a session establishment request message (such as Nsmf_PDUSession_Create Request message) to the private network SMF network element. The visited SMF network element has identified that the terminal device has service superposition of multiple campus DNs, and the session establishment request message to the private network visited SMF network element can carry private information elements to instruct the private network UPF Wang Yuan (the auxiliary anchor point UPF network element of campus DN2) to perform NAT64 (or NAT64+DNS64). The private network SMF network element receives the private network session establishment request message and can carry private information elements in the N4 interface session establishment / update request message (such as PFCP SessionEstablishment / Modification Request message) to the private network UPF to instruct the private network UPF to perform NAT64 (or NAT64+DNS64).

[0259] Step 6: The visited SMF network element sends an update request message (such as PFCP SessionModification Request message) to the diversion UPF. The message can indicate through private information elements that the intelligent diversion UPF is only allowed to divert the packets corresponding to the IPv6 address of campus DN2 to the home campus DN2.

[0260] Step 7: The private network UPF network element (the auxiliary anchor UPF network element of campus DN2) performs NAT64 (or NAT64+DNS64).

[0261] Since the terminal may use a DNS request message with an outer IPv6 address to request an A record, the private network UPF network element (the auxiliary anchor UPF network element of campus DN2) can also discard the DNS request message with the requested address type as an A record when performing NAT64+DNS64.

[0262] Figure 13 The explanation is given using the example of a terminal device activating a session outside the coverage of the visited campus DN1 (such as a campus) and then moving to the coverage of the campus DN1. It can be understood that the terminal device can also activate a session within the coverage of the visited campus DN1 (such as a campus), and the visited SMF network element receives the control policy of the campus DN1 in the session establishment request.

[0263] in addition, Figure 13The following example illustrates the execution of NAT64 (or NAT64+DNS64) by the auxiliary anchor point UPF network element of the dedicated DN (home campus DN2) generated later. In some implementations, when the terminal device has a home dedicated DN and a visited dedicated DN, the auxiliary anchor point UPF network element of the visited dedicated DN can also be fixed to execute NAT64 (or NAT64+DNS64). In the above step 4, after the visited SMF network element identifies the service superposition with a dedicated DN (such as campus DN), it can actively deactivate the session of the terminal device. When the terminal device subsequently reactivates the session, it obtains the diversion strategy of the visited dedicated DN (campus DN1) and the home DN (campus DN2) at the same time. The visited SMF network element identifies that the terminal device has a dedicated DN superposition and executes the diversion strategy for the visited dedicated DN (campus DN1). Figure 12 The processing shown.

[0264] It is understandable that in order to implement the functions in the above embodiments, the control plane network element (such as the SMF network element, the PCF network element) and the first anchor point UPF network element include hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0265] See also Figure 14 , Figure 14 This is a schematic diagram of the structure of a communication device according to an embodiment of the present application. The communication device may include units or modules corresponding to all or part of the steps in the above method embodiment, and may be used to execute the steps executed by the control plane network element or the first anchor point UPF network element in the above embodiment. For details, please refer to the relevant description in the above method embodiment.

[0266] like Figure 14 As shown, the communication device 1400 includes a processing unit 1410 and an interface unit 1420, wherein the processing unit 1410 can be a processor or a processing circuit, and the interface unit 1420 can also be a transceiver unit or an input / output interface. The communication device 1400 can be used to implement the steps performed by the control plane network element or the first anchor point UPF network element in the above embodiment.

[0267] When the communication device 1400 is used to implement the steps performed by the control plane network element in the above embodiment:

[0268] The processing unit 1410 is configured to determine whether a service of the first dedicated data network exists on the terminal device;

[0269] Interface unit 1420 is used to send first indication information to the first anchor user plane function network element corresponding to the first dedicated data network, where the first indication information instructs the first anchor user plane function network element to perform network address translation, where the network address translation is used to convert the IPv6 address of the first dedicated data network carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the first dedicated data network, and / or convert the IPv4 address of the first dedicated data network carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the first dedicated data network.

[0270] For other implementation methods, please refer to the relevant introduction of the control plane network element or the first anchor point UPF network element in the aforementioned embodiments, which will not be repeated here.

[0271] like Figure 15 As shown, the present application also provides a communication device 1500, including a processor 1510, and may also include a communication interface 1520. The processor 1510 and the communication interface 1520 are coupled to each other. It is understandable that the communication interface 1520 can be a transceiver, an input / output interface, an input interface, an output interface, an interface circuit, etc. Optionally, the communication device 1500 may further include a memory 1530 for storing instructions executed by the processor 1510 or storing input data required by the processor 1510 to execute instructions or storing data generated after the processor 1510 executes instructions. The memory 1530 may be a physically independent unit, or may be coupled to the processor 1510, or the processor 1510 may include the memory 1530.

[0272] When the communication device 1500 is used to implement the steps performed by the control plane network element or the first anchor point UPF network element in the above embodiment, the processor 1510 can be used to implement the functions of the above processing unit 1410, and the communication interface 1520 can be used to implement the functions of the above interface unit 1420.

[0273] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), logic circuits, field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0274] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a mobile hard disk, a CD-ROM or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a network device or a terminal device. Of course, the processor and the storage medium can also be present in a network device or a terminal device as discrete components.

[0275] In the above embodiments, all or part of the embodiments can be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments can 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 program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instructions can be transmitted from one network device, terminal, computer, server, or data center to another network device, terminal, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disk; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

[0276] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0277] Furthermore, it should be understood that in the embodiments of this application, the word "exemplary" is used to indicate an example, illustration, or description. Any embodiment or design described in this application as "exemplary" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner.

[0278] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

Claims

1. A communication method, characterized in that: include: The control plane network element determines that the terminal device has a service on the first dedicated data network; The control plane network element sends first indication information to the first anchor user plane function network element corresponding to the first dedicated data network, and the first indication information instructs the first anchor user plane function network element to perform network address translation, and the network address translation is used to convert the IPv6 address of the first dedicated data network carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the first dedicated data network, and / or, convert the IPv4 address of the first dedicated data network carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the first dedicated data network.

2. The method according to claim 1, wherein The network address translation is also used to convert the IPv6 address of the terminal device carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the terminal device, and / or to convert the IPv4 address of the terminal device carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the terminal device.

3. The method according to claim 1 or 2, wherein: The method further comprises: The control plane network element sends a first diversion rule to the diversion user plane function network element, and the first diversion rule instructs the diversion user plane function network element to divert the message sent by the terminal device to the first dedicated data network to the first anchor user plane function network element according to the IPv6 address of the first dedicated data network.

4. The method according to any one of claims 1 to 3, wherein The IPv6 address prefix corresponding to the first private data network is used for conversion between the IPv4 address and the IPv6 address of the first private data network, wherein different private data networks correspond to different IPv6 address prefixes.

5. The method according to any one of claims 1 to 4, wherein The first indication information also instructs the first anchor user plane functional network element to perform domain name system DNS conversion, and the DNS conversion is used to convert the address type requested in the DNS request message sent by the terminal device to the first dedicated data network from AAAA record to A record, and / or modify the IPv4 address of the A record in the DNS response message sent by the first dedicated data network to the terminal device to the IPv6 address of the AAAA record.

6. The method according to any one of claims 1 to 5, wherein Before the control plane network element sends the first indication information to the first anchor user plane function network element corresponding to the first dedicated data network, the method further includes: The control plane network element determines that the terminal device has at least one second dedicated data network service in addition to the first dedicated network service.

7. The method according to claim 6, wherein The control plane network element is a session management network element, and the control plane network element determines that the terminal device has at least one second dedicated data network service in addition to the first dedicated data network service, including: The session management network element determines that in addition to receiving the first control policy corresponding to the first dedicated data network, at least one second control policy corresponding to the at least one second dedicated data network is also received.

8. The method according to claim 6, wherein The control plane network element is a policy control network element, and the control plane network element determines that the terminal device has at least one service of the second dedicated data network in addition to the service of the first dedicated data network, including: The policy control network element determines that the terminal device is subscribed to the first private data network and the at least one second private network.

9. The method according to any one of claims 6 to 8, wherein The first private data network and the at least one second private data network are private data networks of a visited location of the terminal device; or The first private data network and the at least one second private data network are home private data networks of the terminal device; or, The first private data network is a visited private data network of the terminal device, and the at least one second private data network is a home private data network of the terminal device; or The first private data network is a home private data network of the terminal device, and the at least one second private data network is a visited private data network of the terminal device.

10. A communication method, characterized in that: include: The first anchor user plane function network element receives first indication information from the control plane network element, where the first indication information instructs the first anchor user plane function network element to perform network address translation, where the first anchor user plane function network element is an anchor user plane function network element corresponding to the first dedicated data network; The first anchor user plane function network element converts the IPv6 address of the first dedicated data network carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the first dedicated data network, and / or converts the IPv4 address of the first dedicated data network carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the first dedicated data network.

11. The method according to claim 10, wherein The method further comprises: The first anchor user plane functional network element converts the IPv6 address of the terminal device carried in the message sent by the terminal device to the first dedicated data network into the IPv4 address of the terminal device, and / or converts the IPv4 address of the terminal device carried in the message sent by the first dedicated data network to the terminal device into the IPv6 address of the terminal device.

12. The method according to claim 11, wherein The first anchor user plane function network element performs the network address translation based on the IPv4 and IPv6 dual stack addresses of the terminal device and the IPv6 address prefix corresponding to the first dedicated data network.

13. The method according to any one of claims 10 to 12, wherein: The first indication information further instructs the first anchor user plane function network element to perform domain name system (DNS) conversion. The method further includes: The first anchor user plane functional network element performs DNS conversion, and the DNS conversion is used to convert the address type requested in the DNS request message sent by the terminal device to the first dedicated data network from an AAAA record to an A record, and / or modify the IPv4 address of the A record in the DNS response message sent by the first dedicated data network to the terminal device to an IPv6 address of an AAAA record.

14. The method according to claim 13, wherein The first anchor user plane function network element discards the DNS request message with the address type of A record sent by the terminal device to the first dedicated data network.

15. The method according to any one of claims 10 to 14, wherein: The control plane network element is a session management network element or a policy control network element.

16. A communication device, characterized in that: The method comprises a unit for performing the method according to any one of claims 1 to 9 or the method according to any one of claims 10 to 15.

17. A communication device, characterized in that: The device comprises a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor, or to send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method according to any one of claims 1 to 9 or the method according to any one of claims 10 to 15 through a logic circuit or execution instruction.

18. A computer program product, characterized in that The method comprises a computer program or an instruction, which, when executed by a processor, enables the method according to any one of claims 1 to 9 or the method according to any one of claims 10 to 15 to be implemented.

19. A chip system, characterized in that: The chip system includes: A processor and an interface, wherein the processor is used to call and execute instructions from the interface, and when the processor executes the instructions, the method according to any one of claims 1 to 9 or the method according to any one of claims 10 to 15 is implemented.

20. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction. When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 9 or the method according to any one of claims 10 to 15 is implemented.

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