WO2022143697A1 - 避免环路的方法及装置 - Google Patents

避免环路的方法及装置 Download PDF

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Publication number
WO2022143697A1
WO2022143697A1 PCT/CN2021/142184 CN2021142184W WO2022143697A1 WO 2022143697 A1 WO2022143697 A1 WO 2022143697A1 CN 2021142184 W CN2021142184 W CN 2021142184W WO 2022143697 A1 WO2022143697 A1 WO 2022143697A1
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network element
port
terminal device
user plane
stp
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PCT/CN2021/142184
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English (en)
French (fr)
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朱强华
吴问付
朱奋勤
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华为技术有限公司
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Publication of WO2022143697A1 publication Critical patent/WO2022143697A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/18—Loop-free operations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/48—Routing tree calculation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a method and apparatus for avoiding loops.
  • 5G local area network (5GLAN) service is a service provided by the current 5G network, which is mainly used in home communication, corporate office, factory manufacturing, car networking, power grid transformation and public security organs.
  • the 5GLAN service can provide Internet Protocol (IP) type or non-IP type (such as Ethernet type) private communication for two or more terminal devices in a group of terminal devices.
  • IP Internet Protocol
  • non-IP type such as Ethernet type
  • the devices in the factory form a group, and different devices can send Ethernet packets to each other; or, the office equipment (such as mobile phones, computers or laptops, etc.) of employees in a department in the enterprise Groups, different office devices can send IP packets to each other, and so on.
  • the 5GLAN service can forward broadcast data for group members, for example, a broadcast message sent by one terminal device is forwarded to other terminal devices in the group.
  • the PDU session from the terminal device to the user plane network element can be regarded as a link between switches. Therefore, there may be redundant links in the network formed by 5G LAN and stock LAN, forming a loop.
  • the 5G LAN includes UPF1 and UPF2, UPF1 communicates with LAN#1 and LAN#2, and UPF2 communicates with LAN#2 and LAN#3. It can be seen that there are multiple loops in the network, such as loop 1 existing between UPF1, LAN#1 and LAN#2, and loop 2 existing between UPF2, LAN#2 and LAN#3.
  • the present application provides a method and device for avoiding loops, which are used to avoid loops in a network formed by 5G LAN and existing LAN in the scenario of interworking between 5G LAN and existing LAN.
  • a first aspect provides a method for avoiding loops, comprising: a session management network element receiving a protocol data unit (protocol data unit, PDU) session establishment request message from a first terminal device; the session management network element according to the PDU session establishment request message, select the first user plane network element; the session management network element sends first indication information to the first user plane network element, where the first indication information is used to instruct activation of the spanning tree protocol (spanning tree protocol, STP) function.
  • PDU protocol data unit
  • STP spanning tree protocol
  • the session management network element sends the first indication information to the first user plane network element, so that the first user plane network element activates the STP function, Thereby, loops in the network are avoided, and the normal communication of the network is ensured.
  • the first indication information is used to instruct to activate the STP function, including: the first indication information is used to instruct to activate the STP function for the group to which the first terminal device belongs.
  • the first indication information includes an identifier of a group to which the first terminal device belongs.
  • the first indication information is also used to indicate the STP version.
  • the first indication information is carried in the N4 interface message.
  • the method further includes: the session management network element sends a parameter for configuring the first user plane network element to activate the STP function to the first user plane network element. Based on this design, the management of the topology of the spanning tree can be achieved indirectly.
  • the parameters for configuring the first user plane network element to activate the STP function include one or more of the following: bridge priority, bridge media access control (MAC) address, first port the priority of the first port, the port number of the first port, the port number of the second port, the priority of the second port, the port number of the third port, or the priority of the third port; wherein, the first port is the first user plane The port corresponding to the PDU session on the network element, the second port is the port corresponding to the tunnel connected to the second user plane network element on the first user plane network element, and the third port is the first user plane network element used for communication with the data network connected interface.
  • bridge priority bridge media access control
  • the session management network element sends the first indication information to the first user plane network element, including: the session management network element obtains operator policy information according to the identifier of the group to which the first terminal device belongs; When the policy information is used to indicate that the STP function is allowed to be activated, the session management network element sends the first indication information to the first user plane network element. Based on this design, it is possible to control whether the session management network element sends the first indication information through the operator policy information, thereby realizing indirect management of whether the first user plane network element activates the STP function.
  • the session management network element sends the first indication information to the first user plane network element, including: the session management network element obtains the information from the unified data management network element according to the identifier of the group to which the first terminal device belongs. Subscription information of a group to which a terminal device belongs; when the subscription information includes indication information for instructing activation of the STP function, the session management network element sends the first indication information to the first user plane network element. Based on this design, whether the session management network element sends the first indication information can be controlled through subscription information, thereby implementing indirect management of whether the first user plane network element activates the STP function.
  • the session management network element sends the first indication information to the first user plane network element, including: the session management network element obtains the policy and charging control rule of the first terminal device from the policy control function network element; When the policy and charging control rule includes indication information for instructing activation of the STP function, the session management network element sends the first indication information to the first user plane network element. Based on this design, whether the session management network element sends the first indication information can be controlled through policies and charging control rules, thereby realizing indirect management of whether the first user plane network element activates the STP function.
  • the session management network element sends the first indication information to the first user plane network element, including: the session management network element locally obtains the user plane topology of the 5GLAN related to the group to which the first terminal device belongs; When there are multiple ports for connecting to the data network in the user plane topology of the 5G LAN, or there are multiple user plane network elements in the user plane topology of the 5G LAN, the session management network element sends the first indication information to the first user plane network element. . Based on this design, the operation of the session management network element sending the first indication information can meet the objective conditions of the user plane topology of the 5G LAN, and ensure normal communication between the 5G LAN and the stock LAN.
  • the method further includes: the session management network element sends second indication information to the first terminal device, where the second indication information is used to instruct the first terminal device to activate the STP function. Based on this design, the first terminal device can activate the STP function according to the second indication information to avoid loops in the network.
  • the second indication information is also used to indicate the STP version.
  • the method further includes: the session management network element sends a parameter for configuring the first terminal device to activate the STP function to the first terminal device. Based on this design, the topology management of spanning tree can be realized indirectly.
  • the parameters for configuring the first terminal device to activate the STP function include one or more of the following: the port number of the fourth port or the priority of the fourth port, where the fourth port is on the first terminal device.
  • the session management network element sends the second indication information to the first terminal device, including: the session management network element obtains first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports STP Function; when the first STP capability information is used to indicate that the first terminal device supports the STP function, the session management network element sends the second indication information to the first terminal device. Based on this design, it can be avoided that the configuration of the first terminal device contradicts the indication of the session management network element.
  • the PDU session establishment request message includes the first STP capability information.
  • the method further includes: the session management network element obtains the first STP capability information from the mobility management network element. It should be understood that the mobility management network element may acquire the first STP capability information from the first terminal device.
  • the method further includes: when the first user plane network element does not provide services for any terminal equipment in the group to which the first terminal equipment belongs, the session management network element sends the first user plane network element to the first user plane network element.
  • the element sends third indication information, where the third indication information is used to instruct to deactivate the STP function.
  • the first user plane network element does not need to receive unnecessary BPDU packets, so as to reduce the pressure of the first user plane network element to process the packets.
  • a method for avoiding loops including: a first user plane network element receiving first indication information sent by a session management network element, where the first indication information is used to instruct activation of the STP function; the first user plane network element According to the first indication information, the STP function is activated.
  • the first user plane network element activates the STP function according to the first indication information, which can avoid loops in the network.
  • the first indication information is used to instruct to activate the STP function, including: the first indication information is used to instruct to activate the STP function for the group to which the first terminal device belongs.
  • the first indication information includes an identifier of a group to which the first terminal device belongs.
  • the first indication information is also used to indicate the STP version.
  • the first indication information is carried in the N4 interface message.
  • the method further includes: the first user plane network element receives a parameter sent by the session management network element for configuring the first user plane network element to activate the STP function.
  • the parameters for configuring the first user plane network element to activate the STP function include one or more of the following: bridge priority, bridge media access control MAC address, priority of the first port, first The port number of the port, the port number of the second port, the priority of the second port, the port number of the third port, or the priority of the third port; wherein, the first port corresponds to the PDU session on the first user plane network element
  • the second port is a port on the first user plane network element that corresponds to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the method further includes: the first user plane network element receives third indication information sent by the session management network element, where the third indication information is used to instruct to deactivate the STP function; Three instructions to deactivate the STP function.
  • a method for avoiding loops including: a first terminal device sends a PDU session establishment request message to a session management network element; the first terminal device receives second indication information sent by the session management network element, the second indication The information is used to instruct the first terminal device to activate the STP function.
  • the first terminal device when the first terminal device establishes a PDU session to access the 5GLAN, the first terminal device receives the second indication information sent by the session management network element, and activates the STP function according to the second indication information, so that the network can be avoided. A loop appears in the .
  • the second indication information is also used to indicate the STP version.
  • the method further includes: the first terminal device receives a parameter sent by the session management network element and used for configuring the first terminal device to activate the STP function.
  • the parameters used when configuring the first terminal device to activate the STP function include one or more of the following parameters: the port number of the fourth port, or the priority of the fourth port, the fourth port is the port corresponding to the PDU session on the first terminal device.
  • the PDU session establishment request message includes first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports STP.
  • the method further includes: the first terminal device sends first STP capability information to the mobility management network element in the registration process, where the first STP capability information is used to indicate whether the first terminal device supports the STP function. Based on this design, in the subsequent process, the mobility management network element may send the first STP capability information to the session management network element.
  • a method for avoiding loops including: a session management network element receives a PDU session establishment request message from a first terminal device; and the session management network element selects a first user plane network element according to the PDU session establishment request message ; The session management network element sends the first message to the first terminal device, and the first message is used to determine the bridge identifier of the local area network bridge LAN bridge, and the LAN bridge includes the first user plane network element and the first terminal device.
  • the session management network element when the first terminal device establishes a PDU session to access the 5GLAN, the session management network element sends the first message to the first terminal device, so that the first terminal device and the first user plane network element form a LAN bridge to run STP to avoid loops in the network.
  • the first terminal device and the first user plane network element form a LAN bridge, which can reduce the number of LAN bridges (or switches) in the network and simplify the topology of the network.
  • the first message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the first message includes the bridge identification of the LAN bridge.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element. It should be understood that using multiple terminal devices and user plane network elements as a LAN bridge can make the access/exit of terminal devices only affect the port status on one LAN bridge, so that the access of a larger number of terminal devices In the process of exiting and/or exiting, topology management can be simplified, and spanning tree can be quickly converged.
  • the second terminal device and the first terminal device belong to the same group.
  • the first message includes second indication information
  • the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the method further includes: the session management network element sends a second message to the first user plane network element, where the second message is used to determine the bridge identifier of the LAN bridge. Based on this design, the session management network element sends the first message to the first user plane network element, so that the first terminal device and the first user plane network element form a LAN bridge to run STP, thereby avoiding loops in the network.
  • the second message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the second message includes the bridge identification of the LAN bridge.
  • the second message further includes first indication information, where the first indication information is used to indicate activation of the STP function.
  • the first indication information is also used to indicate the STP version.
  • the second message further includes an identifier of the group to which the first terminal device belongs.
  • the method further includes: the session management network element sends a parameter for configuring the first user plane network element to activate the STP function to the first user plane network element.
  • the parameters include one or more of the following: the port number of the second port, the priority of the second port, the QoS parameter of the second port, the port number of the third port, or the priority of the third port
  • the second port is a port on the first user plane network element that corresponds to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the session management network element sends the first message to the first terminal device, including: the session management network element obtains, according to the identifier of the group to which the first terminal device belongs, the operation information associated with the group to which the first terminal device belongs. Operator policy information; when the operator policy information is used to indicate activation of the STP function, the session management network element sends a first message to the first terminal device. Based on this design, whether the session management network element sends the first message can be controlled through the operator policy information, thereby realizing indirect management of whether the first terminal device activates the STP function.
  • the session management network element sends the first message to the first terminal device, including: the session management network element obtains subscription information with the group to which the first terminal device belongs according to the identifier of the group to which the first terminal device belongs. ; In the case that the subscription information includes indication information for indicating activation of the STP function, the session management network element sends a first message to the first terminal device. Based on this design, whether the session management network element sends the first message can be controlled through subscription information, thereby realizing indirect management of whether the first terminal device activates the STP function.
  • the session management network element sends the first message to the first terminal device, including: the session management network element obtains the policy and charging control rule of the first terminal device from the policy control function network element; If the fee control rule includes indication information for instructing to activate the STP function, the session management network element sends the first message to the first terminal device. Based on this design, whether the session management network element sends the first message can be controlled through policies and charging control rules, thereby realizing indirect management of whether the first terminal device activates the STP function.
  • the session management network element sends the first message to the first terminal device, including: the session management network element locally obtains the 5GLAN user plane topology related to the group to which the first terminal device belongs; When there are multiple ports for connecting to the data network in the topology, or there are multiple user plane network elements in the user plane topology of the 5G LAN, the session management network element sends the first message to the first terminal device. Based on this design, the operation of the session management network element sending the first message can meet the objective conditions of the user plane topology of the 5G LAN, and ensure the normal communication between the 5G LAN and the stock LAN.
  • the session management network element sends the first message to the first terminal device, including: the session management network element obtains first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports the STP function ; When the first STP capability information is used to indicate that the first terminal device supports the STP function, the session management network element sends the first message to the first terminal device. Based on this design, it can be avoided that the configuration of the first terminal device contradicts the indication of the session management network element.
  • the PDU session establishment request message includes the first STP capability information.
  • the method further includes: the session management network element obtains the first STP capability information from the mobility management network element. It should be understood that the mobility management network element may receive the first STP capability information sent by the first terminal device in the registration process of the first terminal device.
  • a fifth aspect provides a method for avoiding loops, comprising: the first user plane network element receives a second message, and the second message is used to determine the bridge identifier of the LAN bridge where the first user plane network element is located, and the LAN bridge includes the first user plane network element.
  • the session management network element sends the first message to the first user plane network element, so that the first terminal device and the first user plane network element form a LAN bridge to run STP, thereby avoiding loops in the network.
  • the second message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the second message includes the bridge identification of the LAN bridge.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the second message further includes first indication information, where the first indication information is used to indicate activation of the STP function.
  • the first indication information is also used to indicate the STP version.
  • the second message further includes an identifier of the group to which the first terminal device belongs.
  • the method further includes: the first user plane network element receives a parameter sent by the session management network element for configuring the first user plane network element to activate the STP function.
  • the parameters include one or more of the following: the port number of the second port, the priority of the second port, the QoS parameter of the second port, the port number of the third port, or the priority of the third port
  • the second port is a port on the first user plane network element corresponding to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the method further includes: the first user plane network element sends a fourth configuration BPDU message through the port of the first user plane network element, and the value of the root bridge identifier field in the fourth configuration BPDU message is set to be: The bridge ID of the LAN bridge.
  • the method further includes: the first user plane network element receives the third configuration BPDU message through the port of the first user plane network element; the first user plane network element receives the third configuration BPDU message through the first terminal device and the first user In the PDU session between the plane network elements, a third configuration BPDU message is sent to the first terminal device.
  • the first terminal device can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first user plane network element.
  • the method further includes: the first user plane network element receives, through the PDU session, a second configuration BPDU message sent by the first terminal device, where the second configuration BPDU message is received by the port of the first terminal device.
  • the received configuration BPDUs Based on this design, the first user plane network element can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first terminal device.
  • the method further includes: the first user plane network element determines the bridge role of the LAN bridge according to the fourth configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is: root bridge or non-root bridge.
  • a method for avoiding loops including: a first terminal device sends a PDU session establishment request message to a session management network element, where the PDU session establishment request message is used to request the establishment of a PDU session; the first terminal device receives a session management The first message sent by the network element. The first message is used to determine the bridge identifier of the LAN bridge.
  • the LAN bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected.
  • the first terminal device when the first terminal device establishes a PDU session to access the 5G LAN, the first terminal device receives the first message sent by the session management network element, so that the first terminal device and the first user plane network element form a LAN bridge to run STP to avoid loops in the network.
  • the first message includes the bridge identification of the LAN bridge.
  • the first message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the first message further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the method also includes: the first terminal device sends a first configuration BPDU message through the port of the first terminal device according to the bridge identifier of the LAN bridge, and the value of the root bridge identification field in the first configuration BPDU message is obtained. The value is set to the bridge ID of the LAN bridge.
  • the method further includes: the first terminal device receives the second configuration BPDU message through the port of the first terminal device; the first terminal device sends the second configuration to the first user plane network element through the PDU session BPDU message.
  • the first user plane network element can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first terminal device.
  • the method also includes: when the value of the root bridge identification field of the second configuration BPDU message is the bridge identification of the LAN Bridge, the first terminal device will receive the port of the second configuration BPDU message Set to blocking state. Based on this design, the first terminal device can identify the internal port of the LAN bridge, and set the internal port to a blocking state to avoid loops inside the LAN bridge.
  • the method further includes: the first terminal device receives, through the PDU session, a third configuration BPDU message sent by the first user plane network element, where the third configuration BPDU message is sent by the first user plane network element.
  • Configuration BPDUs received by the port Based on this design, the first terminal device can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first user plane network element.
  • the method also includes: the first terminal device determines the bridge role of the LAN bridge according to the first configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is the root bridge. Or a non-root bridge.
  • the PDU session establishment request message includes first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports STP.
  • the method further includes: the first terminal device sends first STP capability information to the mobility management network element in the registration process, where the first STP capability information is used to indicate whether the first terminal device supports the STP function. Based on this design, in the subsequent process, the mobility management network element may send the first STP capability information to the session management network element.
  • a method for avoiding loops comprising: an application function network element receiving a third message, the third message including a first container, and the first container including STP information related to the first terminal device; The third message sends a third container to the first terminal device, where the third container is used to determine the bridge identifier of the LAN bridge, where the LAN bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected.
  • the application function network element obtains the STP information related to the first terminal device by receiving the third message, and then indirectly learns that the first terminal device accesses the 5G LAN by establishing a PDU session. After that, the application function network element runs STP by sending the third container to the first terminal device, so that the first terminal device and the first user plane network element form a LAN bridge to avoid loops in the network.
  • the third container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the third container includes the bridge ID of the LAN bridge.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the STP information related to the first terminal device includes first STP capability information and/or first STP version information
  • the first STP capability information is used to indicate whether the first terminal device supports the STP function
  • the first STP The version information is used to indicate the STP version supported by the first terminal device.
  • the third container further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the third message further includes an identifier of the group to which the first terminal device belongs.
  • the third message further includes a second container, and the second container includes STP information related to the first user plane network element.
  • the STP information related to the first user plane network element includes second STP capability information and/or second STP version information, and the second STP capability information is used to indicate whether the first user plane network element supports the STP function.
  • the second STP version information is used to indicate the STP version supported by the first user plane network element.
  • the method further includes: the application function network element sends a fourth container to the first user plane network element, where the fourth container is used to determine the bridge identifier of the LAN bridge.
  • the fourth container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the fourth container includes the bridge identification of the LAN bridge.
  • the fourth container further includes first indication information, where the first indication information is used to instruct to activate the STP function.
  • a method for avoiding loops including: a first terminal device sends a first container to an application function network element, where the first container includes STP information related to the first terminal device; the first terminal device receives the application function network element The third container sent by the element, the third container is used to determine the bridge identifier of the LAN bridge, and the LAN bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected; the first terminal device according to the third container, Activate the STP function.
  • the first terminal device receives the third container sent by the application function network element, thereby activating the STP function to avoid loops in the network. And, based on this technical solution, the first terminal device and the first user plane network element will operate STP as a LAN bridge. It should be understood that forming a LAN bridge with the first terminal device and the first user plane network element can reduce the number of LAN bridges (or switches) in the network and simplify the topology of the network.
  • the third container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the third container includes the bridge ID of the LAN bridge.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group. It should be understood that using multiple terminal devices and user plane network elements as a LAN bridge can make the access/exit of terminal devices only affect the port status on one LAN bridge, so that the access of a larger number of terminal devices In the process of exiting and/or exiting, topology management can be simplified, and spanning tree can be quickly converged.
  • the STP information related to the first terminal device includes first STP capability information and/or first STP version information
  • the first STP capability information is used to indicate whether the first terminal device supports the STP function
  • the first STP The version information is used to indicate the STP version supported by the first terminal device.
  • the third container further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the method further includes: the first terminal device sends the first configuration BPDU message through the port of the first terminal device according to the bridge identifier of the LAN bridge, and the value of the root bridge identification field in the first configuration BPDU message is obtained. The value is set to the bridge ID of the LAN bridge.
  • the method further includes: the first terminal device receives the second configuration BPDU message through the port of the first terminal device.
  • the first terminal device sends a second configuration BPDU message to the first user plane network element through the PDU session.
  • the first user plane network element can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first terminal device.
  • the method also includes: when the value of the root bridge identification field of the second configuration BPDU message is the bridge identification of the LAN bridge, the first terminal device will receive the port of the second configuration BPDU message Set to blocking state. Based on this design, the first terminal device can identify the internal port of the LAN bridge, and set the internal port to a blocking state to avoid loops inside the LAN bridge.
  • the method further includes: the first terminal device receives, through the PDU session, a third configuration BPDU message sent by the first user plane network element, where the third configuration BPDU message is sent by the first user plane network element.
  • Configuration BPDUs received by the port Based on this design, the first terminal device can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first user plane network element.
  • the method also includes: the first terminal device determines the bridge role of the LAN bridge according to the first configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is the root bridge. Or a non-root bridge.
  • a ninth aspect provides a method for avoiding loops, comprising: a first user plane network element receiving a fourth container sent by an application function network element, and the fourth container is used to determine a bridge identifier of a LAN bridge, where the LAN bridge includes the first user The plane network element and the first terminal device connected to the first user plane network element; the first user plane network element activates the STP function according to the fourth container.
  • the first user plane network element receives the fourth container sent by the application function network element, thereby activating the STP function to avoid loops in the network. And, based on this technical solution, the first terminal device and the first user plane network element will run STP as a LAN bridge. It should be understood that forming a LAN bridge with the first terminal device and the first user plane network element can reduce the number of LAN bridges (or switches) in the network and simplify the topology of the network.
  • the fourth container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the bridge identifier of the LAN bridge is included in the fourth container.
  • the LAN bridge also includes a second terminal device connected to the first user plane network element. It should be understood that using multiple terminal devices and user plane network elements as a LAN bridge can make the access/exit of terminal devices only affect the port status on one LAN bridge, so that the access of a larger number of terminal devices In the process of exiting and/or exiting, topology management can be simplified, and spanning tree can be quickly converged.
  • the second terminal device and the first terminal device belong to the same group.
  • the fourth container further includes first indication information, where the first indication information is used to instruct the first user plane network element to activate the STP function.
  • the method further includes: the first user plane network element sends a second container to the session management network element, where the second container includes STP information related to the first user plane network element.
  • the STP information related to the first user plane network element includes second STP capability information and/or second STP version information, and the second STP capability information is used to indicate whether the first user plane network element supports the STP function.
  • the second STP version information is used to indicate the STP version supported by the first user plane network element.
  • the method further includes: the first user plane network element sends a fourth configuration BPDU message through the port of the first user plane network element according to the bridge identifier of the LAN bridge, and the root bridge in the fourth configuration BPDU message is sent.
  • the value of the ID field is set to the bridge ID of the LAN bridge.
  • the method further includes: the first user plane network element receives the third configuration BPDU message through the port of the first user plane network element; the first user plane network element receives the third configuration BPDU message through the first terminal device and the first user In the PDU session between the plane network elements, a third configuration BPDU message is sent to the first terminal device.
  • the first terminal device can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first user plane network element.
  • the method further includes: the first user plane network element receives, through the PDU session, a second configuration BPDU message sent by the first terminal device, where the second configuration BPDU message is received by the port of the first terminal device.
  • the received configuration BPDUs Based on this design, the first user plane network element can be made to know the information (eg, bridge identifier, port identifier, etc.) of the device connected to the first terminal device.
  • the method further includes: the first user plane network element determines the bridge role of the LAN bridge according to the fourth configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is: root bridge or non-root bridge.
  • a communication device including a processing module and a communication module.
  • the communication module is configured to receive a PDU session establishment request message from the first terminal device.
  • the processing module is configured to select the first user plane network element according to the PDU session establishment request message.
  • the communication module is further configured to send first indication information to the first user plane network element, where the first indication information is used to instruct to activate the STP function.
  • the first indication information is used to instruct to activate the STP function, including: the first indication information is used to instruct to activate the STP function for the group to which the first terminal device belongs.
  • the first indication information includes an identifier of a group to which the first terminal device belongs.
  • the first indication information is also used to indicate the STP version.
  • the first indication information is carried in the N4 interface message.
  • the communication module is further configured to send a parameter for configuring the first user plane network element to activate the STP function to the first user plane network element.
  • the parameters for configuring the first user plane network element to activate the STP function include one or more of the following: bridge priority, bridge media access control (MAC) address, first port the priority of the first port, the port number of the first port, the port number of the second port, the priority of the second port, the port number of the third port, or the priority of the third port; wherein, the first port is the first user plane The port corresponding to the PDU session on the network element, the second port is the port corresponding to the tunnel connected to the second user plane network element on the first user plane network element, and the third port is the first user plane network element used for communication with the data network connected interface.
  • bridge priority bridge media access control
  • the communication module is specifically configured to obtain the operator policy information according to the identifier of the group to which the first terminal device belongs; in the case that the operator policy information is used to indicate that the STP function is allowed to be activated, to the first user
  • the plane network element sends the first indication information.
  • the communication module is specifically configured to obtain the subscription information of the group to which the first terminal device belongs from the unified data management network element according to the identifier of the group to which the first terminal device belongs; In the case of activating the indication information of the STP function, the first indication information is sent to the first user plane network element.
  • the communication module is specifically configured to acquire the policy and charging control rule of the first terminal device from the policy control function network element; In this case, the first indication information is sent to the first user plane network element.
  • the communication module is specifically used to obtain the user plane topology of the 5GLAN related to the group to which the first terminal device belongs; there are multiple ports for connecting to the data network in the user plane topology of the 5GLAN, or When there are multiple user plane network elements in the user plane topology of the 5G LAN, the first indication information is sent to the first user plane network element.
  • the communication module is specifically configured to send second indication information to the first terminal device, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the communication module is specifically configured to send a parameter for configuring the first terminal device to activate the STP function to the first terminal device.
  • the parameters for configuring the first terminal device to activate the STP function include one or more of the following: the port number of the fourth port or the priority of the fourth port, where the fourth port is on the first terminal device.
  • the communication module is specifically configured to obtain the first STP capability information, and the first STP capability information is used to indicate whether the first terminal device supports the STP function; when the first STP capability information is used to indicate the first terminal device When the STP function is supported, the second indication information is sent to the first terminal device.
  • the PDU session establishment request message includes the first STP capability information.
  • the communication module is further configured to acquire the first STP capability information from the mobility management network element.
  • the communication module is further configured to send the first user plane network element to the first user plane network element when the first user plane network element does not provide services for any terminal equipment in the group to which the first terminal equipment belongs.
  • the third indication information is used to instruct to deactivate the STP function.
  • a communication device including a processing module and a communication module.
  • the communication module is configured to receive first indication information sent by the session management network element, where the first indication information is used to instruct activation of the STP function.
  • the processing module is specifically configured to activate the STP function according to the first indication information.
  • the first indication information is used to instruct to activate the STP function, including: the first indication information is used to instruct to activate the STP function for the group to which the first terminal device belongs.
  • the first indication information includes an identifier of a group to which the first terminal device belongs.
  • the first indication information is also used to indicate the STP version.
  • the first indication information is carried in the N4 interface message.
  • the communication module is further configured to receive a parameter sent by the session management network element for configuring the first user plane network element to activate the STP function.
  • the parameters for configuring the first user plane network element to activate the STP function include one or more of the following: bridge priority, bridge media access control MAC address, priority of the first port, first The port number of the port, the port number of the second port, the priority of the second port, the port number of the third port, or the priority of the third port; wherein, the first port corresponds to the PDU session on the first user plane network element
  • the second port is a port on the first user plane network element that corresponds to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the communication module is further configured to receive third indication information sent by the session management network element, where the third indication information is used to instruct to deactivate the STP function; the first user plane network element deactivates the STP function according to the third indication information. Activate the STP function.
  • a twelfth aspect provides a communication device, comprising: a communication module and a processing module. Among them, the communication module is used for
  • the processing module is configured to receive second indication information sent by the session management network element, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the communication module is further configured to receive parameters sent by the session management network element and used for configuring the first terminal device to activate the STP function.
  • the parameters used when configuring the first terminal device to activate the STP function include one or more of the following parameters: the port number of the fourth port, or the priority of the fourth port, the fourth port is the port corresponding to the PDU session on the first terminal device.
  • the PDU session establishment request message includes first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports STP.
  • the communication module is further configured to send first STP capability information in the registration process, where the first STP capability information is used to indicate whether the first terminal device supports the STP function.
  • a thirteenth aspect provides a communication device, including a communication module and a processing module.
  • the communication module is configured to receive a PDU session establishment request message from the first terminal device.
  • the processing module is configured to select the first user plane network element according to the PDU session establishment request message.
  • the communication module is further configured to send a first message to the first terminal device, where the first message is used to determine the bridge identifier of the local area network bridge LAN Bridge, and the LAN Bridge includes the first user plane network element and the first terminal device.
  • the first message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the first message includes the bridge identification of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the first message includes second indication information
  • the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the communication module is further configured to send a second message to the first user plane network element, where the second message is used to determine the bridge identifier of the LAN Bridge.
  • the second message also includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the second message includes the bridge identification of the LAN bridge.
  • the second message further includes first indication information, where the first indication information is used to indicate activation of the STP function.
  • the first indication information is also used to indicate the STP version.
  • the second message further includes an identifier of the group to which the first terminal device belongs.
  • the communication module is further configured to send a parameter for configuring the first user plane network element to activate the STP function to the first user plane network element.
  • the parameters include one or more of the following: the port number of the second port, the priority of the second port, the QoS parameter of the second port, the port number of the third port, or the priority of the third port
  • the second port is a port on the first user plane network element corresponding to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the communication module is specifically configured to obtain operator policy information associated with the group to which the first terminal device belongs according to the identifier of the group to which the first terminal device belongs; when the operator policy information is used to indicate activation of the STP When the function is enabled, the first message is sent to the first terminal device.
  • the communication module is specifically configured to acquire subscription information with the group to which the first terminal device belongs according to the identifier of the group to which the first terminal device belongs; the subscription information includes indication information for indicating activation of the STP function. In the case of , send the first message to the first terminal device.
  • the communication module is specifically configured to acquire the policy and charging control rule of the first terminal device from the policy control function network element; In this case, the first message is sent to the first terminal device.
  • the communication module is specifically used to obtain the user plane topology of the 5GLAN related to the group to which the first terminal device belongs; there are multiple ports for connecting to the data network in the user plane topology of the 5GLAN, or When there are multiple user plane network elements in the user plane topology of the 5G LAN, the first message is sent to the first terminal device.
  • the communication module is specifically configured to obtain the first STP capability information, and the first STP capability information is used to indicate whether the first terminal device supports the STP function; when the first STP capability information is used to indicate the first terminal device When the STP function is supported, the first message is sent to the first terminal device.
  • the PDU session establishment request message includes the first STP capability information.
  • the communication module is further configured to acquire the first STP capability information from the mobility management network element.
  • a fourteenth aspect provides a communication apparatus, which is applied to a first user plane network element.
  • the communication device includes a processing module and a communication module.
  • the communication module is used to receive a second message, and the second message is used to determine the bridge identifier of the LAN Bridge where the first user plane network element is located, and the LAN Bridge includes the first user plane network element and the first user plane network element connected to the first user plane network element.
  • the processing module is configured to activate the STP function according to the second message.
  • the second message includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the second message includes the bridge identification of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the second message further includes first indication information, where the first indication information is used to indicate activation of the STP function.
  • the first indication information is also used to indicate the STP version.
  • the second message further includes an identifier of the group to which the first terminal device belongs.
  • the communication module is specifically configured to receive a parameter sent by the session management network element for configuring the first user plane network element to activate the STP function.
  • the parameters include one or more of the following: the port number of the second port, the priority of the second port, the QoS parameter of the second port, the port number of the third port, or the priority of the third port
  • the second port is a port on the first user plane network element corresponding to the tunnel connected to the second user plane network element
  • the third port is an interface on the first user plane network element for connecting to the data network.
  • the communication module is also used to send the fourth configuration BPDU message through the port of the first user plane network element according to the bridge identification of the LAN Bridge, and the value of the root bridge identification field in the fourth configuration BPDU message Set to the bridge ID of the LAN Bridge.
  • the communication module is further configured to receive the third configuration BPDU message through the port of the first user plane network element; A terminal device sends a third configuration BPDU.
  • the communication module is further configured to receive a second configuration BPDU packet sent by the first terminal device through the PDU session, where the second configuration BPDU packet is a configuration BPDU packet received by the port of the first terminal device.
  • the processing module is also used to determine the bridge role of the LAN Bridge according to the fourth configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is a root bridge or a non-root bridge. bridge.
  • a fifteenth aspect provides a communication apparatus, which is applied to a first terminal device.
  • the communication device includes: a communication module and a processing module.
  • the communication module is used to send a PDU session establishment request message to the session management network element, and the PDU session establishment request message is used to request the establishment of a PDU session; the first message sent by the session management network element is received, and the first message is used to determine the LAN Bridge
  • the bridge identifier of the LAN Bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected.
  • the processing module is configured to activate the STP function according to the first message.
  • the first message may include the bridge priority and/or bridge MAC address of the LAN bridge.
  • the first message includes the bridge identification of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the first message further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the communication module is also used to send the first configuration BPDU message through the port of the first terminal device, and the value of the root bridge identification field in the first configuration BPDU message is set to the bridge identification of the LAN Bridge.
  • the communication module is further configured to receive the second configuration BPDU message through the port of the first terminal device; and send the second configuration BPDU message to the first user plane network element through the PDU session.
  • the processing module is also used to set the port that received the second configuration BPDU message to be blocked when the value of the root bridge identification field of the second configuration BPDU message is the bridge identification of the LAN Bridge. state.
  • the communication module is further configured to receive the third configuration BPDU message sent by the first user plane network element through the PDU session, and the third configuration BPDU message is received by the port of the first user plane network element. configuration BPDUs.
  • the processing module is also used to determine the bridge role of the LAN bridge according to the first configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is a root bridge or a non-root bridge. bridge.
  • the PDU session establishment request message includes first STP capability information, where the first STP capability information is used to indicate whether the first terminal device supports STP.
  • the communication module is further configured to send the first STP capability information to the mobility management network element in the registration process, where the first STP capability information is used to indicate whether the first terminal device supports the STP function.
  • a sixteenth aspect provides a communication device, comprising: a processing module and a communication module.
  • the communication module is configured to receive a third message, where the third message includes a first container, and the first container includes STP information related to the first terminal device.
  • the processing module is configured to generate a third container according to the third message.
  • the communication module is further configured to send a third container to the first terminal device, where the third container is used to determine the bridge identifier of the LAN bridge, and the LAN Bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected.
  • the third container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the third container includes the bridge ID of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the STP information related to the first terminal device includes first STP capability information and/or first STP version information
  • the first STP capability information is used to indicate whether the first terminal device supports the STP function
  • the first STP The version information is used to indicate the STP version supported by the first terminal device.
  • the third container further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the third message further includes an identifier of the group to which the first terminal device belongs.
  • the third message further includes a second container, and the second container includes STP information related to the first user plane network element.
  • the STP information related to the first user plane network element includes second STP capability information and/or second STP version information, and the second STP capability information is used to indicate whether the first user plane network element supports the STP function.
  • the second STP version information is used to indicate the STP version supported by the first user plane network element.
  • the communication module is further configured to send a fourth container to the first user plane network element, and the fourth container is used to determine the bridge identifier of the LAN Bridge.
  • the fourth container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the fourth container includes the bridge identification of the LAN bridge.
  • the fourth container further includes first indication information, where the first indication information is used to instruct to activate the STP function.
  • a seventeenth aspect provides a communication apparatus, which is applied to a first terminal device.
  • the communication device includes: a processing module and a communication module.
  • the communication module is used to send the first container to the application function network element, where the first container includes STP information related to the first terminal device; receive the third container sent by the application function network element, and the third container is used to determine the LAN bridge
  • the bridge identifier, the LAN Bridge includes the first terminal device and the first user plane network element to which the first terminal device is connected.
  • the processing module is used for activating the STP function according to the third container.
  • the third container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the third container includes the bridge ID of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the STP information related to the first terminal device includes first STP capability information and/or first STP version information
  • the first STP capability information is used to indicate whether the first terminal device supports the STP function
  • the first STP The version information is used to indicate the STP version supported by the first terminal device.
  • the third container further includes second indication information, where the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is also used to indicate the STP version.
  • the communication module is also used to send the first configuration BPDU message through the port of the first terminal device, and the value of the root bridge identification field in the first configuration BPDU message is set to the bridge identification of the LAN Bridge.
  • the communication module is further configured to receive the second configuration BPDU message through the port of the first terminal device; and send the second configuration BPDU message to the first user plane network element through the PDU session.
  • the processing module is used to set the port receiving the second configuration BPDU message to a blocking state when the value of the root bridge identification field of the second configuration BPDU message is the bridge identification of the LAN Bridge .
  • the communication module is further configured to receive the third configuration BPDU message sent by the first user plane network element through the PDU session, and the third configuration BPDU message is received by the port of the first user plane network element. configuration BPDUs.
  • the processing module is also used to determine the bridge role of the LAN Bridge according to the first configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is a root bridge or a non-root bridge. bridge.
  • a communication apparatus which is applied to a first user plane network element.
  • the communication device includes: a processing module and a communication module.
  • the communication module is also used to receive the fourth container sent by the application function network element.
  • the fourth container is used to determine the bridge identifier of the LAN Bridge.
  • the LAN Bridge includes the first user plane network element and the first user plane network element connected to the first user plane network element. Terminal Equipment.
  • the processing module is further configured to activate the STP function according to the fourth container.
  • the fourth container includes the bridge priority and/or bridge MAC address of the LAN bridge.
  • the fourth container includes the bridge identification of the LAN bridge.
  • the LAN Bridge further includes a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the fourth container further includes first indication information, where the first indication information is used to instruct the first user plane network element to activate the STP function.
  • the communication module is further configured to send a second container to the session management network element, where the second container includes STP information related to the first user plane network element.
  • the STP information related to the first user plane network element includes second STP capability information and/or second STP version information, and the second STP capability information is used to indicate whether the first user plane network element supports the STP function.
  • the second STP version information is used to indicate the STP version supported by the first user plane network element.
  • the communication module is also used to send the fourth configuration BPDU message through the port of the first user plane network element according to the bridge identification of the LAN Bridge, and the value of the root bridge identification field in the fourth configuration BPDU message Set to the bridge ID of the LAN Bridge.
  • the communication module is further configured to receive the third configuration BPDU message through the port of the first user plane network element; A terminal device sends a third configuration BPDU.
  • the communication module is further configured to receive a second configuration BPDU packet sent by the first terminal device through the PDU session, where the second configuration BPDU packet is a configuration BPDU packet received by the port of the first terminal device.
  • the processing module is also used to determine the bridge role of the LAN Bridge according to the fourth configuration BPDU message, the second configuration BPDU message and the third configuration BPDU message, and the bridge role is a root bridge or a non-root bridge. bridge.
  • a nineteenth aspect provides a communication device, including a processor and a communication interface, where the processor is configured to execute computer program instructions, so that the communication device implements any one of the designs provided in any one of the first to ninth aspects. method to avoid loops.
  • a twentieth aspect provides a computer-readable storage medium, where the computer-readable storage medium stores instructions that, when the instructions are executed on a computer, enable the computer to implement any one of the first to ninth aspects.
  • a design involves avoiding loops.
  • a twenty-first aspect provides a computer program product comprising computer instructions, which, when the computer program product runs on a computer, enables the computer to implement any one of the designs provided in any one of the first to ninth aspects. method to avoid loops.
  • a twenty-second aspect provides a chip, the chip includes a processor and a transceiver, when the processor executes computer program instructions, the implementation of any of the designs provided in any one of the first to ninth aspects involves method to avoid loops.
  • Figure 1 is a schematic diagram of the interworking scenario between 5G LAN and stock LAN;
  • FIG. 2 is a schematic diagram of the system architecture of 5GLAN
  • FIG. 3 is a schematic diagram of the architecture of a 5G network according to an embodiment of the present application.
  • FIG. 4(a) is a schematic diagram of a scenario of interworking between 5G LAN and existing LAN provided by an embodiment of the present application;
  • FIG. 4(b) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 4(c) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 4(d) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 4(e) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN according to an embodiment of the present application
  • FIG. 5 is a flowchart of a method for avoiding loops provided by an embodiment of the present application.
  • FIG. 6 is a flowchart of another method for avoiding loops provided by an embodiment of the present application.
  • FIG. 7(a) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 7(b) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application.
  • FIG. 8(a) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 8(b) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application.
  • FIG. 9 is a flowchart of a method for avoiding loops provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application.
  • FIG. 11 is a flowchart of another method for avoiding loops provided by an embodiment of the present application.
  • FIG. 13 is a flowchart of another method for avoiding loops provided by an embodiment of the present application.
  • 15 is a flowchart of another method for avoiding loops provided by an embodiment of the present application.
  • FIG. 16(a) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • FIG. 16(b) is a schematic diagram of another scenario of interworking between 5G LAN and stock LAN provided by an embodiment of the present application;
  • 17 is a flowchart of a method for managing an STP function provided by an embodiment of the present application.
  • FIG. 18 is a schematic structural diagram of a communication device according to an embodiment of the present application.
  • FIG. 19 is a schematic structural diagram of another communication apparatus provided by an embodiment of the present application.
  • the 5G core network supports the PDU connection service.
  • the PDU connection service is the service of exchanging PDU data packets between the terminal device and the data network (DN).
  • the PDU connection service is realized through the establishment of a PDU session initiated by the terminal device.
  • the terminal device establishes a PDU session, that is, a data transmission channel between the terminal device and the DN is established.
  • terminal device may initiate the establishment of one or more PDU sessions to connect to the same DN or different DNs.
  • Terminal equipment can be composed of a set of core network elements (such as session management function (SMF) network elements, policy control function (PCF) network elements and user plane function (UPF) network elements. etc.) services, these core network elements coordinate and manage the PDU session resources of the terminal equipment.
  • SMF session management function
  • PCF policy control function
  • UPF user plane function
  • the N4 session is created by the SMF on the UPF to manage the functions of the UPF serving the PDU session. For example, when the terminal device establishes a PDU session, the SMF may instruct the UPF to create an N4 session corresponding to the PDU session. When the SMF receives the request to delete the PDU session, the SMF will trigger the UPF to delete the N4 session corresponding to the PDU session. In some cases, the SMF may also trigger the UPF to modify the N4 session corresponding to the PDU session.
  • the N4 session may be divided into an N4 session at the user level (or terminal device level) and an N4 session at the group level.
  • the N4 session context may include: N4 session ID, N4 routing rules for the N4 session, including: packet detection rule (PDR), forwarding action rule (FAR), quality of services (quality of services) , QoS) enforcement rule (QoS enforcement rule, QER) and statistics reporting rule (usage reporting rule, URR).
  • PDR packet detection rule
  • FAR forwarding action rule
  • QoS quality of services
  • QoS enforcement rule QER
  • statistics reporting rule usage reporting rule
  • UPF implements detection and forwarding of packets of a PDU session by using parameters such as PDR, FAR, QER, and URR in the context of an N4 session.
  • the UPF uses the PDR to determine the N4 session to which the message belongs. Then, the UPF uses the PDR (possibly one or more) in the N4 session context to match the characteristic information of the packet, and finds a PDR that matches the packet.
  • the PDR associates or specifies the FAR, QER, and URR corresponding to the packet. Therefore, the UPF can perform drop (drop), forward (forward), buffer (buffer), report to the control plane (notify), or duplicate (duplicate) operations on the packet according to the FAR.
  • UPF can perform QoS operations on packets based on QER.
  • UPF can report statistics on packets based on URR.
  • STP Spanning tree protocol
  • STP works at the data link layer and is used to generate a loop-free logical topology structure in Ethernet, which can prevent loops caused by redundant links of switches.
  • the principle is: if any switch reaches the root bridge, there are two Or more than two links, achieve path redundancy through a certain algorithm, and at the same time prune the loop network into a loop-free tree network, so as to ensure that there is only a single active link between any two switches and avoid reporting The proliferation and infinite looping of text in loop networks.
  • this root node is called the root bridge.
  • the root bridge is the logical center of the entire network, but not necessarily the physical center of the network. Devices other than the root bridge in the network can be called non-root bridges. It should be understood that in the event of changes in the network topology, the root bridge may also change.
  • the two basic metrics of the STP algorithm are identity (ID) and path cost.
  • the ID is divided into a bridge identity (BID) and a port identity (PID).
  • BID bridge identity
  • PID port identity
  • BID is composed of bridge priority and bridge MAC address. Taking the BID occupying 8 bytes as an example, the first 2 bytes of the 8 bytes occupied by the BID are used to carry the bridge priority, and the last 6 bytes are used to carry the bridge MAC address. In an STP network, the device with the smallest BID is elected as the root bridge.
  • PID consists of port priority and port number.
  • the PID is used in some cases as a basis for selecting a specific port on the device.
  • Path cost is a port variable and is a reference value used by STP to select links. By calculating the path cost, STP selects relatively "strong" links, blocks redundant links, and prunes the network into a loop-free tree network topology.
  • the root path cost (RPC) of a port is the accumulation of the path costs of the ports of the bridges that pass through the path from the port to the root bridge.
  • STP changes the ring network topology into a tree network topology, mainly considering the following three elements: root bridge, root port (root port, RP) and designated port (designated port, DP).
  • the root bridge is the device with the smallest BID in the network.
  • the root port refers to the port closest to the root bridge path on the device.
  • the port is responsible for forwarding data in the direction of the root bridge.
  • On a device running STP there is one and only one root port. It should be understood that there is no root port on the root bridge.
  • the main selection criterion for the root port is determined based on the root path cost (RPC). Among all STP-enabled ports on a device, the one with the lowest root path cost is the root port.
  • each network segment of the ring network will elect a designated port, and the switching device with the designated port on a network segment is called the designated bridge of the network segment.
  • alternate port (alternate port, AP).
  • An alternate port provides the device with an alternate path to the root bridge.
  • the device can use an alternate port to communicate with the root bridge.
  • STP includes the following port states.
  • the BPDU message mainly includes the following fields: a root bridge identity (root identity, RID) field, a root path cost field, a bridge identity (bridge identity, BID) field, and a port identification field.
  • the root bridge identification field is set to the BID of the root bridge considered by the switch sending the BPDU packet
  • the root path cost field is set to the port of the switch sending the BPDU packet to the root bridge.
  • Shortest path cost for a BPDU packet
  • the bridge ID field is set to the BID of the switch that sent the BPDU.
  • the port ID field is set to the PID of the port of the switch that sends the BPDU.
  • BPDUs are generally sent at a specified time interval.
  • STP mainly includes election process and maintenance process.
  • the election process includes the following steps:
  • the devices in the network compare the BIDs of each device by exchanging BPDUs, and select the device with the smallest BID as the root bridge.
  • the root bridge will send a BPDU message with itself as the root bridge with a default notification period of 2 seconds.
  • Other switches select a root port according to the received BPDU message, and send the BPDU message Replace the BID with its own BID, and then forward it to other connected switches from its designated port.
  • Other ports on the device that are not designated ports and root ports will be blocked.
  • the maintenance process includes the following steps:
  • the root bridge After the network completes the election process, in order to maintain the stability of the network, the root bridge continues to periodically send BPDUs, and the blocked ports on the device continuously listen to the BPDUs sent by the peer. If the BPDU is not received within a certain period of time, the blocking state on the device considers that the network has changed, which triggers the network to re-calculate the convergence.
  • the 3rd generation partnership project (3GPP) proposes to support one-to-one and one-to-many communications for 5GLAN.
  • the 3GPP network is required to support group-based unicast, multicast and broadcast, to support the replication and distribution of multicast and broadcast packets, and to support any terminal device as a Multicast source.
  • the current 3GPP technical specification (TS) 23.501 defines that a 5G LAN is managed by an SMF.
  • the SMF manages one or more UPFs simultaneously.
  • the SMF manages UPF1 and UPF2 as an example for drawing. Routing rules are maintained on UPF1 and UPF2, and UPF1 and UPF2 can forward packets according to the routing rules maintained by themselves. It is assumed that terminal device 1, terminal device 2, and terminal device 3 belong to the same group.
  • terminal device 1, terminal device 2, and terminal device 3 belong to the same group.
  • data is transmitted in a UPF local switch manner.
  • data needs to be transmitted through the tunnel between UPF1 and UPF2.
  • two UPFs may exchange tunnel information through SMF to establish a tunnel.
  • the tunnel (or forwarding path) between UPFs can use virtual local area network (virtual LAN, VLAN), virtual extended local area network (virtual extensible LAN, VxLAN), general packet radio service (general packet radio service, GPRS) tunnel protocol user plane (GPRS tunneling protocol-user plane, GTP-U), general routing encapsulation protocol (generic routing encapsulation, GRE) or IP tunnel to build.
  • the foregoing construction manner may be dynamic, or may be pre-configured in the network, which is not specifically limited in this embodiment of the present application.
  • the tunnel information when constructed in a VLAN mode, may be UPF ID, UPF ID+Virtual Local Area Network Identification (VLAN ID, VID) or media access control (media access control, MAC)+VID; or, for example, when constructed in a VxLAN mode, The tunnel information can be UPF ID, UPF ID+VID, IP address+VID, or IP address+port number (port)+VID; or, for example, when constructed in GTP-U mode, the tunnel information can be UPF ID, UPF ID+tunnel Endpoint identifier (tunnel endpoint identifier, TEID), IP address + TEID, or IP address + port + TEID; or, for example, when the GRE method is used to construct, the tunnel information can be UPF ID, UPF ID + key (key), IP address + key, or IP address+port+key; or, when the IP tunnel is constructed, the tunnel information can be
  • the UPF ID may be a MAC address or an IP address, or an IP address + port, or the SMF network element or the UPF network element may determine the corresponding MAC address or IP address, or IP address according to the UPF ID +port, here is a unified description, and will not be repeated below.
  • one 5G LAN may provide a group communication service for one group, that is, one 5G LAN may correspond to one group.
  • One SMF or UPF can also provide communication services for multiple groups.
  • 5G LAN can also be called 5G virtual network (5G virtual network, 5G VN), 5G VN group, 5G LAN-VN group, LAN-type service (type service), LAN-VN, Or 5G LAN-type service (type service), etc.
  • 5G virtual network 5G virtual network, 5G VN
  • 5G VN group 5G VN group
  • 5G LAN-VN group 5G LAN-type service (type service)
  • LAN-VN LAN-type service
  • type service LAN-VN
  • type service LAN-VN
  • type service LAN-type service
  • SMF is mainly responsible for all control plane functions of terminal device session management, including UPF selection and control, IP address allocation and management, session quality of service (QoS) management, from PCF Obtain policy and charging control (policy and charging control, PCC) rules, etc.
  • UPF as the anchor point of PDU session connection, is responsible for data packet filtering, data transmission/forwarding, rate control, generation of billing information, user plane QoS processing, uplink transmission authentication, Transmission level verification, downlink data packet buffering, and downlink data notification triggering, etc.
  • a radio access network refers to a RAN node
  • a RAN node may also be referred to as an access network device.
  • it can be a transmission reception point (TRP), base station, various forms of control nodes (eg, network controller, wireless controller (eg, cloud radio access network, CRAN) scenarios under the wireless controller)), etc.
  • the RAN node may be various forms of macro base station, micro base station (also called small cell), relay station, access point (access point, AP), etc., and may also be the antenna panel of the base station.
  • the control node can be connected to multiple base stations, and configure resources for multiple terminal devices covered by the multiple base stations.
  • the names of devices with base station functions may vary.
  • a long term evolution (LTE) system may be called an evolved NodeB (evolved NodeB, eNB or eNodeB), and a 5G system or an NR system may be called a next generation node base station (gNB) , the specific name of the base station is not limited in this application.
  • LTE long term evolution
  • eNB evolved NodeB
  • gNB next generation node base station
  • the RAN node may also be a network device or the like in a future evolved public land mobile network (public land mobile network, PLMN).
  • PLMN public land mobile network
  • the terminal device is an entity on the user side for receiving and/or sending signals.
  • Terminal devices are used to provide one or more of voice services and data connectivity services to users.
  • Terminal equipment may also be referred to as user equipment (UE), terminal, access terminal equipment, subscriber unit, subscriber station, mobile station, remote station, remote terminal equipment, mobile equipment, user terminal equipment, wireless communication equipment, user agent or user device.
  • UE user equipment
  • the terminal device can be a vehicle to everything (V2X) device, such as a smart car (smart car or intelligent car), digital car (digital car), unmanned car (unmanned car or driverless car or pilotless car or automobile) , automatic car (self-driving car or autonomous car), pure electric vehicle (pure EV or Battery EV), hybrid electric vehicle (HEV), range extended EV (REEV), plug-in Hybrid electric vehicle (plug-in HEV, PHEV), new energy vehicle (new energy vehicle), roadside unit (road site unit, RSU).
  • V2X vehicle to everything
  • the terminal device may also be a device to device (device to device, D2D) device, such as an electricity meter, a water meter, and the like.
  • the terminal device may also be a mobile station (mobile station, MS), a subscriber unit (subscriber unit), an unmanned aerial vehicle, an internet of things (IoT) device, a station (station, ST) in a WLAN, a cellular phone (cellular phone) phone), smart phone (smart phone), cordless phone, wireless data card, tablet computer, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital processing ( personal digital assistant (PDA) device, laptop computer (laptop computer), machine type communication (MTC) terminal device, handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, Vehicle-mounted devices, wearable devices (also known as wearable smart devices).
  • the terminal device may also be a terminal device in a next-generation communication system, for example, a terminal device in a 5G system or a terminal device in a future evolved PLMN, NPN, and the like.
  • the current 5G network may also include the following network elements: access and mobility management function (core access and mobility management function, AMF) network element, authentication server function (authentication server function, AUSF) ) network element, network slice selection function (NSSF) network element, network exposure function (NEF) network element, network exposure function Repository Function (NRF) network element, policy control A function (policy control function, PCF) network element, a unified data management (unified data management, UDM) network element, an application function (application function, AF) network element, etc., are not specifically limited in this embodiment of the present application.
  • the terminal device communicates with the AMF network element through the next generation network (Next generation, N) 1 interface (N1 for short), the RAN device communicates with the AMF network element through the N2 interface (N2 for short), and the RAN device communicates with the AMF network element through the N3 interface (N3 for short) It communicates with the UPF network element, and the UPF network element communicates with the DN through the N6 interface (N6 for short).
  • Next generation, N next generation network
  • N2 next generation network
  • N3 N3 for short
  • UPF network element communicates with the DN through the N6 interface (N6 for short).
  • Control plane network elements such as AMF network elements, SMF network elements, UDM network elements, AUSF network elements, or PCF network elements can also use service interfaces for interaction.
  • the service interface provided by the AMF externally can be Namf
  • the service interface provided by the SMF network element can be Nsmf
  • the service interface provided by the UDM network element can be Nudm
  • the PCF network element can provide the external service interface
  • the service-oriented interface can be Npcf
  • the service-oriented interface provided by the AUSF network element externally can be Nausf; it will not be described one by one here.
  • the names of the above service interfaces are only examples and are not specifically limited.
  • the terminal device can access the 5GLAN service by establishing a PDU session, so that the 5GLAN can communicate with the existing LAN.
  • UE1 and UE2 form a local LAN.
  • a PDU session is established between UE1 and UPF1.
  • UPF1 in 5G LAN can connect to the LAN composed of UE1 and UE2, and the LAN composed of UE3, UE4, and UE5.
  • the stock LAN refers to the LAN that is different from the 5G LAN.
  • the existing LAN may be the LAN that the terminal device has connected before establishing the PDU session to access the 5G LAN service.
  • the existing LAN may have other names, such as external LAN, LAN, etc., which are not limited.
  • the 5G LAN and the existing LAN communicate with each other, which may cause loops.
  • loops may cause loops.
  • a PDU session has been established between UE1 and UPF1, and UE1 is also connected to UE2.
  • UE2 initiates a PDU session establishment procedure
  • a PDU session is established between UE2 and UPF1.
  • the communication link between UE2, UE1 and UPF constitutes a loop.
  • a communication link between UE1 and DN1 there is a communication link between UE1 and DN1, and a communication link exists between UPF1 and DN1.
  • a PDU session is established between UE1 and UPF1.
  • the communication link between UE1, UPF1 and DN1 forms a loop.
  • a PDU session has been established between UE1 and UPF1, and UE1 is also connected to UE2.
  • UE2 initiates a PDU session establishment procedure
  • a PDU session is established between UE2 and UPF2, and an N19 tunnel is established between UPF2 and UPF1.
  • the communication link between UE1, UE2, UPF1 and UPF2 forms a loop.
  • a PDU session has been established between UE1 and UPF1, UE1 is also connected to UE2, and UPF1 is also connected to DN1.
  • UE2 initiates a PDU session establishment process
  • a PDU session is established between UE2 and UPF2, an N19 tunnel is established between UPF2 and UPF1, and UPF2 is connected to DN1.
  • the communication link between UE1, UE2, DN1, UPF1 and UPF2 forms a loop.
  • a method for avoiding loops includes the following steps:
  • the first terminal device sends a PDU session establishment request message to a session management network element.
  • the session management network element receives the PDU session establishment request message sent by the first terminal device.
  • the PDU session establishment request message is used to request the establishment of a PDU session.
  • the PDU session establishment request message includes: the identifier of the group to which the first terminal device belongs.
  • the group identifier is used to determine the corresponding 5G LAN group.
  • the identifier of the group can be, for example, a data network name (data network name, DNN), a group identifier (Group ID), a DNN+single network slice selection assistance information (single network slice selection assistance information, S-NSSAI) identifier, and the like.
  • step S101 may be specifically implemented as: the first terminal device sends a PDU session establishment request message to the mobility management network element.
  • the mobility management network element selects a session management network element that provides services for the first terminal device. After that, the mobility management network element sends a PDU session establishment request message to the session management network element.
  • the PDU session establishment request message sent by the first terminal device may include first STP capability information and/or first STP version information.
  • the first STP capability information is used to indicate whether the first terminal device supports the STP function.
  • the first STP version information is used to indicate the STP version supported by the first terminal device.
  • the first terminal device may send the first STP capability information and/or the first STP version information to the mobility management network element during the registration process. Furthermore, the mobility management network element stores the first STP capability information and/or the first STP version information. Afterwards, after the mobility management network element receives the PDU session establishment request message, the mobility management network element may encapsulate the PDU session establishment request message and the first STP capability information and/or the first STP version information into an N11 message, and encapsulate the N11 message Sent to the session management network element.
  • the session management network element selects the first user plane network element according to the PDU session establishment request message.
  • the first user plane network element is used to provide a 5G LAN service for the first terminal device.
  • the session management network element can be based on the location of the first terminal device, the identifier of the group to which the first terminal device belongs, the service scope of each user plane network element managed by the session management network element, the session management network
  • the first user plane network element is selected according to factors such as the service capability of each user plane network element managed by the element.
  • the session management network element sends first indication information to the first user plane network element.
  • the first user plane network element receives the first indication information sent by the session management network element.
  • the first indication information is used to instruct to activate the STP function.
  • the first indication information is used to instruct the first user plane network element to activate the STP function.
  • the first indication information is used to instruct the first user plane network element to activate the STP function for the group to which the first terminal device belongs.
  • the first indication information may include an identifier of a group to which the first terminal device belongs.
  • the first indication information may also be used to indicate the STP version.
  • the STP version may include, but is not limited to: Rapid Spanning Tree Protocol (RSTP) and/or Multiple Spanning Tree Protocol (MSTP).
  • RSTP Rapid Spanning Tree Protocol
  • MSTP Multiple Spanning Tree Protocol
  • the first user plane network element selects an STP version to be used when activating the STP function from the STP versions indicated by the first indication information .
  • the first user plane network element selects one STP version used when activating the STP function from one or more STP versions supported by itself.
  • the first indication information may be carried in an N4 interface message.
  • the first indication information may be carried in a newly added N4 interface message.
  • the first indication information may be carried in an existing N4 interface message, for example, an N4 session creation/modification message corresponding to a PDU session.
  • step S103 may be specifically implemented as: in the case that the first preset condition is satisfied, the session management network element sends the first indication information to the first user plane network element.
  • the first preset condition may include one or more of the following:
  • Condition 1-1 The operator policy information obtained by the session management network element is used to indicate that the STP function is allowed to be activated.
  • the operator policy information can be used to control whether the session management network element sends the first indication information, and then indirectly control whether to trigger the first user plane network element to activate the STP function, so as to achieve better management of the operator network and satisfy the Different needs in different scenarios.
  • the session management network element may obtain operator policy information from an operation and maintenance management (operation administration and maintenance, OAM) system.
  • OAM operation administration and maintenance
  • the operator policy information may be applied to the entire operator network, or the operator policy information may be applied to a group to which the first terminal device belongs.
  • the operator policy information when used to indicate that the STP function is allowed to be activated, the operator policy information may also be used to indicate a part or all of the following:
  • the operator policy information can also be used to indicate whether the user plane network element is used as the root bridge.
  • the session management network element should configure the BID of the first user plane network element to be smaller, so that other devices in the network can elect the first network element.
  • the user plane NE acts as the root bridge.
  • the operator policy information can also be used to indicate whether to reserve the PDU session.
  • the session management network element should configure the PID of the first port on the first user plane network element to be smaller, so that the first port is selected during the STP election process. Determine the root port or the specified port.
  • the first port is a port corresponding to the PDU session between the first user plane network element and the first terminal device on the first user plane network element.
  • the operator policy information can also be used to indicate whether to reserve the N19 tunnel.
  • the session management network element should configure the PID of the second port on the first user plane network element to be smaller, so that the second port can be used during the STP election process.
  • the second port is a port corresponding to the tunnel between the first user plane network element and the second user plane network element on the first user plane network element.
  • operator policy information may affect the parameters for activating the STP function configured by the subsequent session management network element for the first user plane network element.
  • the subscription information of the group to which the first terminal device belongs, obtained by the session management network element, includes indication information for indicating that the STP function is allowed to be activated.
  • the subscription information can be used to control whether the session management network element sends the first indication information, and then indirectly control whether to trigger the first user plane network element to activate the STP function, so as to realize the communication of the 5G LAN associated with the group to which the first terminal device belongs. Better management to meet different needs in different scenarios.
  • the session management network element obtains the subscription information of the group to which the first terminal device belongs from the unified data management network element according to the identifier of the group to which the first terminal device belongs. It should be understood that the session management network element may obtain the identifier of the group to which the first terminal device belongs from the PDU session establishment request message sent by the first terminal device.
  • the unified data management network element may receive configuration information related to the group to which the first terminal device belongs and sent by the application function network element through the network open function network element, and the configuration information related to the group to which the first terminal device belongs may be. Including indication information for indicating that the STP function is allowed to be activated. Therefore, the unified data management network element may add indication information for indicating that the STP function is allowed to be activated to the subscription information of the group to which the first terminal device belongs.
  • the configuration information related to the group to which the first terminal device belongs may further include one or more inventory LAN information, STP version information, and the like, which is not limited.
  • the policy and charging control rule associated with the first terminal device acquired by the session management network element include indication information for indicating activation of the STP function.
  • the policy and charging control rule may be used to control whether the session management network element sends the first indication information, thereby indirectly controlling whether to trigger the first user plane network element to activate the STP function.
  • the session management network element may establish a tunnel in advance with the policy control function network element for transmitting information related to the first terminal device. Furthermore, the session management network element may obtain the policy and charging control rule associated with the first terminal device from the policy control function network element through the tunnel.
  • the policy control function network element may directly receive configuration information related to the group to which the first terminal device belongs, sent by the application function network element; or, the policy control network element may receive the application function network element through the network open function network element.
  • the configuration information related to the group to which the first terminal device belongs is sent by the element.
  • the configuration information related to the group to which the first terminal device belongs may include indication information for indicating that the STP function is allowed to be activated.
  • the policy control function network element may add instruction information for indicating that the STP function is allowed to be activated in the policy and charging control rule associated with each terminal device in the group to which the first terminal device belongs.
  • Condition 1-4 There are multiple ports for connecting to the data network in the 5GLAN user plane topology associated with the group to which the first terminal device belongs; and/or, there are multiple ports in the 5GLAN user plane topology associated with the group to which the first terminal device belongs. user plane network element.
  • the user plane topology of the 5G LAN can affect whether the session management network element sends the first indication information, thereby affecting whether the first user plane network element activates the STP function. Therefore, if the user plane topology of 5GLAN satisfies certain conditions (for example, there are multiple ports used to connect to the data network in the 5GLAN user plane topology, or there are multiple user plane network elements in the 5GLAN user plane topology), it means that a loop occurs in the network. The probability is relatively large, so the session management network element needs to send the first indication information to ensure the normal communication between the 5G LAN and the stock LAN.
  • the session management network element since the session management network element is responsible for managing the 5G LAN, the session management network element can locally obtain the 5GLAN user plane topology associated with the group to which the first terminal device belongs.
  • the first user plane network element supports the STP function.
  • the session management network element may locally obtain the second STP capability information of the first user plane network element.
  • the session management network element may obtain the second STP capability information from the first user plane network element, for example, the session management network element receives an N4 message sent by the first user plane network element, where the N4 message includes the second STP capability information.
  • the second STP capability information is used to indicate whether the first user plane network element supports the STP function.
  • the session management network element may determine whether the first user plane network element supports the STP function according to the second STP capability information.
  • the session management network element may locally obtain the second STP version information of the first user plane network element.
  • the session management network element may acquire the second STP version information from the first user plane network element.
  • the second STP version information is used to indicate the STP version supported by the first user plane network element.
  • the session management network element may select a target STP version from the STP versions supported by the first user plane network element according to the second STP version information, and further instruct the first user plane network element to use the target STP through the first indication information Version.
  • second STP version information and second STP capability information may be integrated into the same information, or different information, which is not limited.
  • the session management network element may further send to the first user plane network element a parameter used for configuring the first user plane network element to activate the STP function.
  • first indication information and the parameters used for configuring the first user plane network element to activate the STP function may be encapsulated in the same message and sent to the first user plane network element.
  • first indication information and the parameters used for configuring the first user plane network element to activate the STP function may also be encapsulated in different messages and sent to the first user plane network element respectively.
  • the parameters used to configure the first user plane network element to activate the STP function may include one or more of the following: a parameter used to determine the bridge identifier of the first user plane network element, and the first user plane network element. Parameters related to the first port on the element, parameters related to the second port on the first user plane network element, or parameters related to the third port on the first user plane network element.
  • the parameters used for configuring the first user plane network element to activate the STP function are specifically introduced below.
  • a parameter for determining the bridge identifier of the first user plane network element for example, the bridge priority and/or the MAC address of the first user plane network element.
  • the session management network element acquires the configuration information of one or more existing LANs. After that, the session management network element determines the bridge priority and/or bridge MAC address of the first user plane network element according to the configuration information of one or more existing LANs.
  • the above-mentioned stock LAN may refer to the LAN connected to the 5G LAN.
  • the configuration information of an existing LAN includes at least the bridge priority and/or the bridge MAC address of the root bridge of the existing LAN.
  • the bridge priority of the first user plane network element is higher than the bridge priority of the root bridge in any existing LAN.
  • the bridge MAC address of the first user plane network element is smaller than the bridge MAC address of the root bridge in any existing LAN.
  • the BID of the first user plane network element can be made smaller than the BID of the root bridge in any existing LAN as much as possible. Therefore, in the election process, the first user plane network element can be elected as the root bridge, so that the data exchanged between the first user plane network element and the first terminal device does not need to be forwarded through other devices in the stock LAN, improving the efficiency of the network. Data security and confidentiality.
  • any one of the following implementation manners 1 to 4 may be adopted.
  • a unified description is provided, and details are not repeated below.
  • the session management network element obtains subscription data associated with the group to which the first terminal device belongs from the unified data management network element according to the identifier of the group to which the first terminal device belongs, where the subscription data includes configuration information of an existing LAN.
  • the unified data management network element may directly obtain the configuration information of the existing LAN from the application function network element.
  • the unified data management network element may acquire the configuration information of the stock LAN from the application function network element through the network open function network element.
  • the unified data management network element adds configuration information of the existing LAN to the subscription data associated with the group to which the first terminal device belongs.
  • the session management network element sends the PCC rule associated with the first terminal device from the policy control function network element, where the PCC rule associated with the first terminal device includes configuration information of the stock LAN.
  • the policy control function network element may directly obtain the configuration information of the existing LAN from the application function network element.
  • the policy control function network element may acquire the configuration information of the stock LAN from the application function network element through the network open function network element.
  • the network element of the policy control function adds the configuration information of the existing LAN to the PCC rule associated with the first terminal device.
  • Implementation mode 3 The session management network element acquires the configuration information of the existing LAN from the first user plane network element.
  • the first user plane network element may actively report the configuration information of the existing LAN to the session management network element.
  • the first user plane network element may report the configuration information of the existing LAN under the instruction of the session management network element.
  • the first user plane network element may first obtain configuration BPDUs of the existing LAN. After that, the first user plane network element determines the configuration information of the existing LAN by parsing the configuration BPDU of the existing LAN.
  • Implementation mode 4 The session management network element acquires the configuration BPDU of the existing LAN from the first user plane network element. After that, the session management network element parses the configuration BPDU of the existing LAN, and determines the configuration information of the existing LAN.
  • the first user plane network element may actively report the configuration BPDU of the existing LAN to the session management network element.
  • the first user plane network element may report the configuration BPDU of the existing LAN to the session management network element under the instruction of the session management network element.
  • the first port is a port corresponding to the PDU session between the first user plane network element and the first terminal device on the first user plane network element.
  • the port priority and port number of the first port are used to determine the port identifier of the first port.
  • the QoS parameter of the first port is used to determine the bandwidth of the first port.
  • the bandwidth of the first port is used to determine the port cost of the first port.
  • Port cost can also be called local path cost.
  • the QoS parameters of the first port may include but are not limited to: session (session) - aggregate maximum bit rate (aggregate maximum bit rate, AMBR), maximum flow bit rate (maximum flow bit rate, MFBR) and/or guarantee Stream bit rate (guaranteed flow bit rate, GFBR).
  • the port identifier and port cost of the first port are used in the process of the first user plane network element performing STP election or STP maintenance.
  • the session management network element acquires the configuration information of one or more existing LANs. Afterwards, the session management network element determines the port number and/or the priority of the first port according to the configuration information of one or more existing LANs.
  • the configuration information of the existing LAN may further include the port number and/or the priority of each port on each device in the existing LAN.
  • the priority of the first port is higher than the priority of a port on any device in any existing LAN.
  • the port number of the first port is smaller than the port number of the port on any device in any one of the existing LANs.
  • the PID of the first port can be made smaller than the PID of the port on any device in any stock LAN as much as possible. Therefore, when the first user plane network element is a non-root bridge, the probability of the first port being elected as a designated port or a root port is increased.
  • the first port is a designated port or a root port
  • the data exchanged between the first user plane network element and the first terminal device does not need to be forwarded by other devices in the stock LAN, which improves the data transmission efficiency. Security and Confidentiality.
  • the second port is a port corresponding to the tunnel between the first user plane network element and the second user plane network element on the first user plane network element.
  • the second user plane network element is a user plane network element in the 5G LAN corresponding to the group described by the first terminal device. That is, the second user plane network element provides services for the terminal devices in the group to which the first terminal device belongs.
  • the tunnel connecting the first user plane network element and the second user plane network element may be an N19 tunnel.
  • the port priority and port number of the second port are used to determine the port identifier of the second port.
  • the QoS parameter of the second port is used to determine the bandwidth of the second port.
  • the bandwidth of the second port is used to determine the port cost of the second port.
  • the QoS parameters of the second port may include but are not limited to: group (group)-AMBR.
  • the port identifier and port cost of the second port are used in the process of the first user plane network element performing STP election or STP maintenance.
  • the number of the second ports is determined according to the actual situation. That is, one or more of the second ports may exist, or none of the second ports may exist.
  • the parameters used to configure the first user plane network element to activate the STP function do not include parameters related to the second port on the first user plane network element. parameter.
  • the session management network element acquires the configuration information of one or more existing LANs. Afterwards, the session management network element determines the port number and/or the priority of the second port according to the configuration information of one or more existing LANs.
  • the configuration information of the existing LAN includes the port number and/or the priority of each port on each device in the existing LAN.
  • the priority of the second port is higher than the priority of the port on any device in any existing LAN.
  • the port number of the second port is smaller than the port number of the port on any device in any one of the existing LANs.
  • the PID of the second port can be made smaller than the PID of the port on any device in any stock LAN as much as possible. Therefore, when the first user plane network element is a non-root bridge, the probability of the second port being elected as a designated port or a root port is increased.
  • the second port is a designated port or a root port
  • the data exchanged between the first user plane network element and the second user plane network element does not need to be forwarded by other devices in the stock LAN, improving the performance of the network. Data security and confidentiality.
  • the third port is a port on the first user plane network element for connecting to the data network.
  • the port on the first user plane network element for connecting with the data network may be an N6 port.
  • the number of the third ports is determined according to the actual situation. That is, one or more of the third ports may exist, or none of the third ports may exist.
  • the parameters used to configure the first user plane network element to activate the STP function do not include parameters related to the third port on the first user plane network element. parameter.
  • the first user plane network element For the third port, the first user plane network element generally calculates the port bandwidth of the third port according to locally stored configuration information related to the third port, and then determines the port cost of the third port.
  • the above parameters used for configuring the first user plane network element to activate the STP function may be carried in different messages.
  • the relevant parameters of the first port may be carried in the N4 session creation/modification request message of the first terminal device
  • the relevant parameters of the second port and the third port may be carried in the N4 of the group to which the first terminal device belongs Session creation/modification request message.
  • the session management network element may also report to the first user plane network element.
  • Send fourth indication information where the fourth indication information may be used to instruct the first user plane network element to configure the port number and/or priority of the first port according to the first preset rule.
  • the first preset rule may include: the priority of the first port is higher than the priority of the port on any device in any stock LAN; and/or the port number of the first port is smaller than that in any stock LAN. The port number of the port on any device.
  • the fourth indication information may have other names, such as PDU session priority reservation indication, which is not limited.
  • the session management network element may also report to the first user plane network element.
  • Send fifth indication information where the fifth indication information is used to instruct the first user plane network element to configure the port number and/or priority of the second port according to the second preset rule.
  • the second preset rule may include: the priority of the second port is higher than the priority of the port on any device in any stock LAN; and/or, the port number of the second port is smaller than that in any stock LAN. The port number of the port on any device.
  • the fifth indication information may have other names, such as N19 tunnel priority reservation indication, which is not limited.
  • the first user plane network element activates the STP function according to the first indication information.
  • the first user plane network element after receiving the first indication information, acquires the parameters used for activating the STP function. After that, the first user plane network element activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first user plane network element performs a maintenance process.
  • the first user plane network element may configure all parameters used when activating the STP function by itself.
  • the first user plane network element may acquire all parameters used for activating the STP function from the session management network element.
  • the first user plane network element may obtain a part of the parameters used for activating the STP function from the session management network element, and configure another part of the parameters used for activating the STP function by itself.
  • the first user plane network element when the first user plane network element activates the STP function, it needs to know the bridge identifier of the first user plane network element, the port identifier of the first port, and the QoS parameters of the first port.
  • the management network element acquires the bridge identifier of the first user plane network element and the QoS parameter of the first port, so that the first user plane network element needs to configure the port identifier of the first port by itself.
  • the following describes a specific implementation manner for the first user plane network element to perform the STP election process.
  • the first user plane network element considers itself to be the root bridge, and sends configuration BPDUs on each port to elect the root bridge. It should be understood that the first user plane network element is configured with at least the first port. Optionally, the first user plane network element is further configured with a second port and/or a third port.
  • the root bridge identifier field in the configuration BPDU is set to the BID of the first user plane network element
  • the bridge identifier field is set to the BID of the first user plane network element
  • the port identifier is set to the BID of the first user plane network element.
  • the field is set to the PID of the first port
  • the root path cost field is set to 0.
  • the root bridge identifier field in the configuration BPDU is set to the BID of the first user plane network element
  • the bridge identifier field is set to the BID of the first user plane network element
  • the port identifier is set to the BID of the first user plane network element.
  • field is set to the PID of the second port
  • the root path cost field is set to 0.
  • the root bridge identifier field in the configuration BPDU is set to the BID of the first user plane network element
  • the bridge identifier field is set to the BID of the first user plane network element
  • the port identifier is set to the BID of the first user plane network element.
  • field is set to the PID of the third port
  • the root path cost field is set to 0.
  • the first user plane network element determines whether the BID of the first user plane network element is the smallest in the network by receiving configuration BPDUs sent by other devices in the network. In the case where the BID of the first user plane network element is the smallest in the network, the first user plane network element is the root bridge. In the case that the BID of the first user plane network element is not the smallest in the network, the first user plane network element is a non-root bridge.
  • each port on the first user plane network element is a designated port. Therefore, the first user plane network element configures each port to be in the forwarding state.
  • the first user plane network element When the first user plane network element is a non-root bridge, the first user plane network element also needs to elect a root port and a designated port.
  • the port For each port on the first user plane network element, the port compares the received configuration BPDU with the configuration BPDU stored on the port. When the priority of the received configuration BPDUs is lower than that of the configuration BPDUs stored on the port, the port discards the received configuration BPDUs. If the received configuration BPDU has a higher priority than the configuration BPDU stored by the port, the port updates the stored configuration BPDU with the received configuration BPDU, or the port discards the previously stored configuration BPDU. , and store the just-received configuration BPDU.
  • the first user plane network element compares the configuration BPDUs stored on each port, and selects the configuration BPDU with the highest priority.
  • the port storing the configuration BPDU with the highest priority is the root port of the first user plane network element. Meanwhile, ports other than the root port are set as alternate ports.
  • the first user plane network element also needs to elect a designated port from the standby ports.
  • the value of the root bridge ID field It should be understood that the smaller the value of the root bridge identifier field in the configuration BPDU packet, the higher the priority of the configuration BPDU packet.
  • the value of the root path cost field It should be understood that if two configuration BPDUs are identical in the root bridge identification field and the port identification field, the smaller the value of the root path cost field, the higher the priority of the configuration BPDU.
  • a target configuration BPDU packet of the port is generated based on the configuration BPDU packet stored on the root port.
  • the target configuration BPDU of the port other than the root port of the first user plane network element has a higher priority than the configuration received from the port of the adjacent device connected to the link
  • the port is determined as a designated port, so that the port can periodically send target configuration BPDUs.
  • the priority of the target configuration BPDU message of the port is lower than that of the configuration BPDU message received from the port of the adjacent device connected by the link, it is determined that the port is a non-designated port.
  • generating a target configuration BPDU packet for the port based on the configuration BPDU packet stored on the root port may include the following operations:
  • the value of the root bridge identifier field of the target configuration BPDU packet is the value of the root bridge identifier field of the configuration BPDU packet stored on the root port.
  • the value of the root path cost field of the target configuration BPDU is determined according to the local path cost of the root port and the value of the root path cost field in the configuration BPDU message stored on the root port.
  • Operation 3 The bridge identifier field of the target configuration BPDU is set to the BID of the first user plane network element, and the port identifier field is set to the port identifier of the port.
  • the first user plane network element will set the root port and the designated port to the forwarding state.
  • the first user plane network element may set other ports except the root port and the designated port to a blocking state.
  • the first user plane network element may store the correspondence between the PID of the port, the port role and the port state.
  • the correspondence between the PID of the port, the port role and the port state may be stored in the list shown in Table 2.
  • the first user plane network element may store the first correspondence in the N4 session context corresponding to the PDU session of the first terminal device, and store the second correspondence and the third correspondence in the group to which the first terminal device belongs. in the context of the group's N4 session.
  • the first correspondence is the correspondence between the PID of the first port, the port role, and the port state.
  • the second correspondence is the correspondence between the PID of the second port, the port role and the port state.
  • the third correspondence is the correspondence between the PID of the third port, the port role, and the port state.
  • the first user plane network element activates the STP function according to the instruction of the session management network element, so as to prune the network composed of the 5G LAN and the existing LAN into a Loop-free tree network topology to avoid loops.
  • the above method for avoiding loops may further include steps S105 - S106 .
  • the session management network element sends second indication information to the first terminal device.
  • the first terminal device receives the second indication information sent by the session management network element.
  • the second indication information is used to instruct the first terminal device to activate the STP function.
  • the second indication information is further used to indicate the STP version.
  • the STP version may include, but is not limited to, RSTP and/or MSTP.
  • the first terminal device selects an STP version to be used when activating the STP function from the STP versions indicated by the second indication information.
  • the first terminal device selects one STP version to be used when activating the STP function from one or more STP versions supported by itself.
  • the second indication information may be carried in a newly added message.
  • the second indication information may be carried in an existing message, for example, the second indication information may be carried in a PDU session establishment complete message.
  • the session management network element when the second preset condition is satisfied, the session management network element sends the second indication information to the first terminal device.
  • the second preset condition may include one or more of the following:
  • Condition 2-1 The operator policy information obtained by the session management network element is used to indicate that the STP function is allowed to be activated.
  • the subscription information of the group to which the first terminal device belongs and obtained by the session management network element includes indication information for indicating that the STP function is allowed to be activated.
  • the policy and charging control rule associated with the first terminal device acquired by the session management network element include indication information for indicating activation of the STP function.
  • Condition 2-4 There are multiple ports for connecting to the data network in the 5GLAN user plane topology associated with the group to which the first terminal device belongs; and/or, there are multiple ports in the 5GLAN user plane topology associated with the group to which the first terminal device belongs. user plane network elements.
  • condition 1-1 For the specific introduction of the above condition 2-1 to condition 2-4, reference may be made to condition 1-1 to condition 1-4, which will not be repeated here.
  • Condition 2-5 The first terminal device supports the STP function.
  • the session management network element may acquire the first STP capability information; further, the session management network element determines whether the first terminal device supports the STP function according to the first STP capability information. It should be understood that the first STP capability information is used to indicate whether the first terminal device supports the STP function.
  • the session management network element may acquire the first STP capability information from the first terminal device.
  • the PDU session establishment request message mentioned in the above step S101 may include the first STP capability information.
  • the session management network element may acquire the first STP capability information from the mobility management network element.
  • the session management network element receives an N11 message sent by the mobility management network element, where the N11 message may include the first STP capability information.
  • the N11 message may further include the PDU session establishment request message mentioned in step S101 above.
  • the mobility management network element may acquire the STP capability information of the first terminal device in the registration process of the first terminal device. For example, the mobility management network element receives a registration request message of the first terminal device, where the registration request message includes STP capability information of the first terminal device.
  • the session management network element may also acquire the first STP version information in the manner of acquiring the first STP capability information, where the first STP version information is used to indicate the STP version supported by the first terminal device.
  • the session management network element can select a target STP version from the STP versions supported by the first terminal device according to the first STP version information, and instruct the first terminal device to use the target STP version through the second indication information.
  • the above-mentioned first STP capability information and the first STP version may be integrated into the same information, or two different pieces of information, which are not limited.
  • the session management network element may also send, to the first terminal device, parameters for configuring the first terminal device to use when activating the STP function.
  • the parameters used for configuring the first terminal device to activate the STP function may include one or more of the following: the port number of the fourth port, the priority of the fourth port, or the QoS parameter of the fourth port.
  • the fourth port is a port on the first terminal device corresponding to the PDU session between the first terminal device and the first user plane network element.
  • the port number of the fourth port and the priority of the fourth port are used to determine the port identifier of the fourth port.
  • the QoS parameter of the fourth port is used to determine the port bandwidth of the fourth port.
  • the port bandwidth of the fourth port is used to determine the port overhead of the fourth port.
  • the QoS parameters of the fourth port may include, but are not limited to: session-AMBR, MFBR, and/or GFBR.
  • the second indication information and the parameter used for configuring the first terminal device to activate the STP function are encapsulated in the same message and sent to the first terminal device.
  • the second indication information and the parameter used for configuring the first terminal device to activate the STP function are encapsulated in different messages and sent to the first terminal device respectively.
  • the first terminal device activates the STP function according to the second indication information.
  • the first terminal device after receiving the second indication information, acquires the parameters used when activating the STP function. After that, the first user plane network element activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first terminal device performs a maintenance process.
  • the first terminal device may acquire all parameters used when activating the STP function from the session management network element.
  • the first terminal device may obtain a part of the parameters used for activating the STP function from the session management network element, and configure another part of the parameters used for activating the STP function by itself.
  • the first terminal device configures its own bridge identifier, and obtains the port number of the fourth port, the priority of the fourth port, and the port bandwidth of the fourth port from the session management network element.
  • the first terminal device considers itself to be the root bridge, and sends configuration BPDUs on each port to elect the root bridge.
  • the root bridge identification field in the configuration BPDU is set to the BID of the first terminal device
  • the bridge identification field is set to the BID of the first terminal device
  • the port identification field is set to the first terminal device.
  • the root path cost field is set to 0.
  • the first terminal device determines whether the BID of the first terminal device is the smallest in the network by receiving configuration BPDUs sent by other devices in the network. In the case where the BID of the first terminal device is the smallest in the network, the first terminal device is the root bridge. In the case that the BID of the first terminal device is not the smallest in the network, the first terminal device is a non-root bridge.
  • each port on the first terminal device is a designated port. Therefore, the first terminal device will configure each port to be in the forwarding state.
  • the first terminal device When the first terminal device is a non-root bridge, the first terminal device also needs to elect a root port and a designated port.
  • the port For each port on the first terminal device, the port compares the received configuration BPDU with the configuration BPDU stored by the port. When the priority of the received configuration BPDUs is lower than that of the configuration BPDUs stored on the port, the port discards the received configuration BPDUs. If the received configuration BPDU has a higher priority than the configuration BPDU stored by the port, the port updates the stored configuration BPDU with the received configuration BPDU, or the port discards the previously stored configuration BPDU. , and store the just-received configuration BPDU.
  • the first terminal device compares the configuration BPDUs stored on each port, and selects the configuration BPDU with the highest priority.
  • the port storing the configuration BPDU message with the highest priority is the root port of the first terminal device. Meanwhile, ports other than the root port are set as alternate ports.
  • a target configuration BPDU message of the port is generated based on the configuration BPDU message stored on the root port.
  • the target configuration BPDU of the port other than the root port of the first terminal device has a higher priority than the configuration BPDU received from the port of the adjacent device connected to the link
  • the message is sent, it is determined that the port is the designated port, so that the port can periodically send the target configuration BPDU message.
  • the priority of the target configuration BPDU message of the port is lower than that of the configuration BPDU message received from the port of the adjacent device connected by the link, it is determined that the port is a non-designated port.
  • generating a target configuration BPDU message for the port based on the configuration BPDU message stored on the root port may include the following operations:
  • the value of the root bridge identifier field of the target configuration BPDU packet is the value of the root bridge identifier field of the configuration BPDU packet stored on the root port.
  • the value of the root path cost field of the target configuration BPDU is determined according to the local path cost of the root port and the value of the root path cost field in the configuration BPDU message stored on the root port.
  • Operation 3 The bridge identifier field of the target configuration BPDU is set to the BID of the first terminal device, and the port identifier field is set to the port identifier of the port.
  • the first terminal device will set the root port and the designated port to the forwarding state.
  • the first terminal device may set other ports except the root port and the designated port to a blocking state.
  • steps S103-S104 may be performed first, and then steps S105-S106 may be performed; or, steps S105-S106 may be performed first, and then steps S103-S104 may be performed; or, steps S105-S106 and steps S103-S104 may be performed simultaneously.
  • the session management network element instructs the first terminal device to activate the STP function, thereby pruning the network composed of the 5G LAN and the existing LAN into a loop-free one Tree-like network topology to avoid loops.
  • SMF sends first indication information to UPF1, so that UPF1 activates the STP function; and SMF sends second indication information to UE1 to Make UE1 activate the STP function.
  • UPF1 is elected as the root bridge
  • the port corresponding to the PDU session of UE1 on UPF1 is set to DP
  • the port corresponding to the PDU session of UE3 on UPF1 is set to DP.
  • the port corresponding to the PDU session on UE1 is set to RP
  • the port used to connect with UE2 on UE1 is set to DP.
  • the port used to connect with UE1 on UE2 is set to RP.
  • the port corresponding to the PDU session on UE3 is set to RP, the port used to connect with UE4 on UE3 is set to DP, and the port used to connect to UE5 on UE3 is set to DP.
  • the port used to connect with UE3 on UE4 is set to RP, and the port used to connect to UE5 on UE4 is set to DP.
  • the port used for connecting with UE3 on UE5 is set as RP, and the port on UE5 used for connecting with UE4 is set as AP. In this way, loops do not occur in the network.
  • UPF1 is elected as the root bridge. All ports on UPF1 are set to DP.
  • the port on UPF2 for connecting with UPF1 is set as RP
  • the port on UPF2 for connecting with UE2 is set as RP
  • the port on UPF2 for connecting with DN1 is set as DP.
  • the port used to connect with UPF1 on UE1 is set as RP, and other ports on UE1 are set as DP.
  • the port used to connect with UE1 on UE2 is set to AP, the port used to connect to UPF2 on UE2 is set to RP, the port used to connect to UE5 on UE2 is set to DP, and the port used to connect to UE6 on UE2 is set to DP.
  • the port on DN1 for connecting with UPF1 is set as RP, and the port on DN1 for connecting with UPF2 is set as AP. In this way, loops do not occur in the network.
  • the topology of the network changes.
  • the network composed of the 5G LAN and the stock LAN also uses the topology generated by running STP before releasing the PDU session, the network composed of the 5G LAN and the stock LAN may be abnormal.
  • the network is pruned to a loop-free topology by running STP.
  • the link between UE1 and UE2 is logically blocked
  • the link between UE6 and UE8 is logically blocked
  • the link between DN1 and UE7 is logically blocked.
  • the link between UE1 and UPF1 is released
  • the link between UPF1 and UPF2 is released
  • the link between UPF1 and DN1 is released.
  • UE1 cannot communicate with other devices (eg, UE2) in the network
  • DN1 cannot communicate with other devices (eg, UE7) in the network.
  • the network is pruned to a loop-free topology by running STP.
  • the link between UE1 and UE2 is logically blocked
  • the link between DN1 and UE7 is logically blocked
  • the link between UE5 and UE6 is logically blocked
  • the link between UE6 and UE8 is logically blocked.
  • the path is logically blocked.
  • UE5's PDU session is released
  • the link between UE5 and UPF6 is released.
  • UE5 cannot communicate with other devices (eg, UE6) in the network.
  • FIGS. 8( a ) and 8 ( b ) indicate that the link between the two devices is logically blocked.
  • the embodiment of the present application provides a method for avoiding loops. As shown in Figure 9, the method includes the following steps:
  • the session management network element determines to release the PDU session of the first terminal device.
  • the session management network element determines to release the PDU session of the first terminal device, including one of the following situations:
  • Scenario 1 The session management network element receives the PDU session release request message sent by the first terminal device.
  • Scenario 2 The session management network element determines to release the PDU session based on a local configuration policy.
  • the session management network element determines to release the PDU session of the first terminal device according to an instruction of a third-party network element such as a policy control function network element and a mobility management network element.
  • a third-party network element such as a policy control function network element and a mobility management network element.
  • the session management network element sends an N4 message 1 to the first user plane network element.
  • the first user plane network element receives the N4 message 1 sent by the session management network element.
  • the N4 message 1 is used to request to release the N4 session corresponding to the PDU session.
  • the N4 message 1 may be an N4 session release request message, which is not limited in this embodiment of the present application.
  • the first user plane network element sets the first port to a disabled state according to the N4 message 1.
  • the first user plane network element sets the port state of the first port to the disabled state in the port information table stored by itself according to the N4 message 1.
  • the port information table Exemplarily, for the port information table, reference may be made to the example in Table 2 above.
  • the first user plane network element will also release the N4 session corresponding to the PDU session according to the N4 message 1.
  • the first user plane network element after the PDU session of the first terminal device is released, the topology of the network changes. Therefore, if the first user plane network element also provides services for other terminal devices in the group to which the first terminal device belongs, the first user plane network element can trigger the network to perform convergence calculation again, so as to re-elect the root bridge, root port and Specify the port.
  • the session management network element sends a PDU session release complete message to the first terminal device.
  • the first terminal device receives the PDU session release complete message sent by the session management network element.
  • the first terminal device sets the fourth port to a disabled state according to the PDU session release completion message.
  • the first terminal device sets the port state of the fourth port to the disabled state in the port information table stored by itself according to the PDU session release completion message.
  • the first terminal device can trigger the network to perform convergence calculation again, so as to re-elect the root bridge, the root port and the designated port.
  • the method for avoiding loops is further: The following steps S206-S207 may be included. It should be understood that steps S206-S207 are optional steps.
  • the session management network element sends an N4 message 2 to the first user plane network element.
  • the first user plane network element receives the N4 message 2 sent by the session management network element.
  • the N4 message 2 is used to release the N4 session of the group to which the first terminal device belongs.
  • the first user plane network element sets the second port and/or the third port to a disabled state according to the N4 message 2.
  • the first user plane network element when the first user plane network element is configured with the second port, the first user plane network element sets the port state of the second port in the port information table stored by itself according to N4 message 2 to disabled state. And, when the first user plane network element is configured with the third port, according to the N4 message 2, the first user plane network element sets the port state of the third port to the disabled state in the port information table stored by itself.
  • the first terminal device and the first user plane network element can set the corresponding port to the disabled state according to the instruction of the session management network element, thereby Trigger the network to re-calculate the convergence to re-elect the root bridge, root port, and designated port.
  • the embodiment shown in FIG. 9 is described with the scenario shown in FIG. 10 .
  • the port on UPF1 for connecting with UE1 is set to the disabled state
  • the port on UPF1 for connecting with UPF2 is set to the disabled state
  • the port on UPF1 for connecting with DN1 is set to the disabled state.
  • the port is set to the disabled state.
  • the port on UE1 for connecting to UPF1 is set to the disabled state.
  • the port on UPF2 used to connect with UPF1 is set to the disabled state.
  • the port on DN1 for connecting to UPF1 is set to the disabled state.
  • the network performs convergence calculation again, so that the link between UE1 and UE2 is connected, and the link between DN1 and UE7 is connected.
  • a method for avoiding loops includes the following steps:
  • the first terminal device sends a PDU session establishment request message to a session management network element.
  • the session management network element receives the PDU session establishment request message sent by the first terminal device.
  • the session management network element selects the first user plane network element according to the PDU session establishment request message.
  • steps S301-S302 For the specific introduction of steps S301-S302, reference may be made to the relevant descriptions of steps S101-S102, which will not be repeated here.
  • the session management network element sends a first message to the first terminal device.
  • the first terminal device receives the first message sent by the session management network element.
  • the first message is used to determine the bridge identifier of the LAN bridge where the first terminal device is located.
  • the first message may include bridge priority and/or bridge MAC address of the LAN bridge.
  • the first message may include the bridge identification of the LAN bridge.
  • the LAN bridge includes a first terminal device and a first user plane network element.
  • the first terminal device and the first user plane network element can participate in the STP election process as a whole (that is, a LAN bridge). Therefore, on the one hand, it can be avoided that the PDU session between the first terminal device and the first user plane network element is logically blocked during the STP election process.
  • using two or more devices as a LAN bridge to participate in the STP election process can reduce the number of LAN bridges (or switches) in the network, thereby simplifying the network topology, so that the network can be faster achieve convergence.
  • the PDU session between the first terminal device and the first user plane network element is not regarded as a port on the first terminal device.
  • the PDU session between the first terminal device and the first user plane network element is not regarded as a port on the first terminal device.
  • the LAN bridge may further include a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the LAN bridge may further include a second user plane network element, and the second user plane network element is a user plane network element in the 5G LAN associated with the group to which the first terminal device belongs.
  • the tunnel between the first user plane network element and the second user plane network element is not regarded as a port on the first user plane network element.
  • the tunnel between the first user plane network element and the second user plane network element is not regarded as a port on the second user plane network element.
  • the LAN bridge may further include a third terminal device connected to the second user plane network element.
  • the third terminal device may belong to the same group as the first terminal device.
  • the session management network element obtains configuration information of one or more existing LANs. After that, the session management network element determines the bridge identification BID of the LAN bridge, such as bridge priority and/or bridge MAC address, according to the configuration information of one or more existing LANs.
  • the above-mentioned stock LAN may refer to the LAN connected to the 5G LAN.
  • the configuration information of an existing LAN includes at least the bridge priority and/or the bridge MAC address of the root bridge of the existing LAN.
  • the bridge priority of the LAN bridge is higher than the bridge priority of the root bridge in any existing LAN.
  • the bridge MAC address of the LAN bridge is less than the bridge MAC address of the root bridge in any of the existing LANs.
  • the BID of the LAN bridge is made smaller than the BID of the root bridge in any stock LAN as much as possible.
  • the LAN bridge can be elected as the root bridge.
  • the first message may further include second indication information.
  • second indication information For the specific introduction of the second indication information, reference may be made to the above description, which will not be repeated here.
  • step S303 may be specifically implemented as: in the case that the second preset condition is satisfied, the session management network element sends the first message to the first terminal device.
  • the second preset condition reference may be made to the above description, which will not be repeated here.
  • the first terminal device activates the STP function according to the first message.
  • the first terminal device After receiving the first message, acquires the parameters used when activating the STP function. Afterwards, the first terminal device activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first terminal device performs a maintenance process.
  • the first terminal device determines the bridge identifier of the LAN bridge, including the following situations:
  • the first terminal device can determine the bridge of the LAN bridge according to the bridge priority and bridge MAC address of the LAN bridge included in the first message. logo.
  • the first terminal device determines the LAN according to the locally configured bridge MAC address of the LAN bridge and the bridge priority of the LAN bridge included in the first message.
  • the bridge logo of the bridge It should be understood that the bridge MAC address of the LAN bridge locally configured by the first terminal device will be the same as the bridge MAC address of the LAN bridge used by the first user plane network element to ensure that the bridge identifiers of the LAN bridge determined by the two devices are the same.
  • the bridge MAC address of the LAN bridge locally configured by the first terminal device can be set according to the factory configuration of the first terminal device, or determined according to negotiation between the first terminal device and the first user plane network element.
  • the first terminal device determines the LAN according to the locally configured bridge priority of the LAN bridge and the bridge MAC address of the LAN bridge included in the first message.
  • the bridge logo of the bridge It should be understood that the bridge priority of the LAN bridge locally configured by the first terminal device will be the same as the bridge priority of the LAN bridge used by the first user plane network element to ensure that the bridge identifiers of the LAN bridge determined by the two devices are the same.
  • the bridge priority of the LAN bridge locally configured by the first terminal device may be set according to the factory configuration of the first terminal device, or determined according to negotiation between the first terminal device and the first user plane network element.
  • the following describes the specific implementation of the STP election process performed by the first terminal device in the LAN bridge.
  • the first terminal device considers the LAN bridge to be the root bridge, and the first terminal device sends a first configuration BPDU message through the port of the first terminal device according to the bridge identifier of the LAN bridge, and the value of the root bridge identifier field in the first configuration BPDU message Set to the bridge ID of the LAN bridge.
  • the first terminal device further receives the second configuration BPDU message through the port of the first terminal device.
  • the first terminal device further forwards the second configuration BPDU message to the first user plane network element through the PDU session between the first terminal device and the first user plane network element. Therefore, the first user plane network element can learn the information (eg, bridge identifier, port identifier, etc.) of the peripheral devices of the first terminal device.
  • the sender device of the second configuration BPDU message belongs to a part of the LAN bridge, so the first terminal
  • the port on the device that receives the second configuration BPDU is used for communication between devices in the LAN bridge, that is, the port is an internal port.
  • the first terminal device can set the port that receives the second configuration BPDU message to a blocking state.
  • the port on one device in the LAN bridge for communicating with another device in the LAN bridge is simply referred to as the internal port of the LAN bridge.
  • the port on a device in a LAN bridge that is used to communicate with devices that do not belong to the LAN bridge is referred to as an external port for short.
  • the first terminal device further receives the third configuration BPDU message forwarded by the first user plane network element through the PDU session between the first terminal device and the first user plane network element.
  • the third configuration BPDU packet is a BPDU packet received by the port of the first user plane network element.
  • the first terminal device can learn information (eg, bridge identifiers, port identifiers, etc.) of peripheral devices of the first user plane network element.
  • the first terminal device determines the bridge role of the LAN bridge according to the second configuration BPDU message, the third configuration BPDU message, and the first configuration BPDU message.
  • the bridge role is root bridge or non-root bridge.
  • the first terminal device determines whether the bridge identifier of the LAN bridge where it is located is the smallest in the network. In the case where the bridge ID of the LAN bridge is the smallest in the network, the LAN bridge is the root bridge. Otherwise, the LAN bridge is a non-root bridge.
  • the port roles of the external ports on each device in the LAN bridge are designated ports, and the port states are all forwarding states.
  • each device in the LAN bridge needs to elect the root port and designated port.
  • the internal port can be set to a blocking state to avoid loops inside the LAN bridge.
  • Internal ports do not participate in the election of root ports and the election of designated ports.
  • the external port For each external port on the LAN bridge, the external port compares the received configuration BPDU with the configuration BPDU stored by the external port. When the priority of the received configuration BPDUs is lower than that of the configuration BPDUs stored by the external port, the external port discards the received configuration BPDUs. If the received configuration BPDU has a higher priority than the configuration BPDU stored by the external port, the external port updates the stored configuration BPDU with the received configuration BPDU, or the external port discards the previously stored configuration. BPDUs, and store the just received configuration BPDUs.
  • Multiple devices in a LAN bridge can exchange configuration BPDUs stored on their respective external ports.
  • the device in the LAN bridge compares the configuration BPDUs stored on each external port in the LAN bridge, and selects the configuration BPDU with the highest priority.
  • the external port storing the configuration BPDU with the highest priority is the root port. For example, if the external port storing the configuration BPDU with the highest priority is the port of the first terminal, that is, the root port of the LAN bridge is the port of the first terminal device.
  • All external ports other than the root port in the LAN bridge are set as alternate ports. For the first terminal device, if there is a root port on the first terminal device, other external ports except the root port on the first terminal device are spare ports; or, if there is no root port on the first terminal device, Then all external ports on the first terminal device are spare ports.
  • the standby port needs to participate in the election of the following designated ports.
  • a target configuration BPDU message of the port is generated based on the configuration BPDU message stored in the root port of the LAN bridge.
  • the priority of the target configuration BPDU packet of the standby port on the first terminal device is higher than that of the configuration BPDU packet received from the port of the adjacent device connected to the link, Make sure that the alternate port is the designated port.
  • the priority of the target configuration BPDU message of the backup port is lower than the configuration BPDU message received from the port of the adjacent device connected by the link, it is determined that the backup port is a non-designated port.
  • generating a target configuration BPDU message for the port based on the configuration BPDU message stored on the root port may include the following operations:
  • the value of the root bridge identifier field of the target configuration BPDU message is the value of the root bridge identifier field of the configuration BPDU message stored on the root port of the LAN bridge.
  • the value of the root path cost field of the target configuration BPDU is determined according to the local path cost of the root port and the value of the root path cost field in the configuration BPDU message stored on the root port.
  • Operation 3 The bridge identifier field of the target configuration BPDU is set to the BID of the first terminal device, and the port identifier field is set to the port identifier of the port.
  • the first terminal device when the root port of the LAN bridge is the port of the first terminal device, the first terminal device will set the root port of the LAN bridge and the designated port on the first terminal device to the forwarding state. After the first terminal device elects the root port and the designated port of the LAN bridge, the first terminal device may set other ports except the root port of the LAN bridge and the designated port on the first terminal device to a blocking state.
  • the first terminal device In the case where the root port of the LAN bridge is not the port of the first terminal device, the first terminal device will set the designated port on the first terminal device to a forwarding state, and set other ports except the designated port to a blocking state .
  • the session management network element when the first terminal device establishes a PDU session to access the 5G LAN service, the session management network element sends the first message to the first terminal device, so that the first terminal device determines the LAN where it is located.
  • the bridge logo of the bridge Further, the first terminal device can participate in the STP election as a part of the LAN bridge to avoid loops in the network.
  • the method for avoiding loops may further include steps S305-S306.
  • the session management network element sends a second message to the first user plane network element.
  • the first user plane network element receives the second message sent by the session management network element.
  • the second message may be used to determine the bridge identification BID of the LAN bridge.
  • the second message may include the bridge identification or bridge priority and/or bridge MAC address of the LAN bridge.
  • the second message may include the bridge identification of the LAN bridge.
  • the second message may include first indication information, where the first indication information is used to instruct the first user plane network element to activate the STP function.
  • first indication information is used to instruct the first user plane network element to activate the STP function.
  • the second message may further include an identifier of a group to which the first terminal device belongs.
  • the second message may further include parameters related to the second port.
  • the parameters related to the second port may include: a port number of the second port, a port priority, and a QoS parameter.
  • the QoS parameter of the second port is used to determine the bandwidth of the second port.
  • the bandwidth of the second port is used to determine the port cost of the second port.
  • the QoS parameters of the second port may include but are not limited to: group-AMBR.
  • step S305 may be specifically implemented as: in the case that the first preset condition is satisfied, the session management network element sends the second message to the first user plane network element.
  • the session management network element sends the second message to the first user plane network element.
  • the first user plane network element activates the STP function according to the second message.
  • the first user plane network element after receiving the second message, acquires the parameters used for activating the STP function. After that, the first user plane network element activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first user plane network element performs a maintenance process.
  • the first user plane network element determines the bridge identifier of the LAN bridge, including the following situations:
  • the first user plane network element can determine the LAN bridge according to the bridge priority and bridge MAC address of the LAN bridge included in the second message. bridge logotype.
  • the first user-plane network element determines the bridge MAC address of the LAN bridge configured locally and the bridge priority of the LAN bridge included in the second message. Determine the bridge ID of the LAN bridge. It should be understood that the bridge MAC address of the LAN bridge locally configured by the first user plane network element will be the same as the bridge MAC address of the LAN bridge used by the first terminal device to ensure that the bridge identifiers of the LAN bridge determined by the two devices are the same. Exemplarily, the bridge MAC address of the LAN bridge locally configured by the first user plane network element may be set according to the factory configuration of the first user plane network element, or determined according to the negotiation between the first terminal device and the first user plane network element.
  • the first user plane network element receives the information according to the locally configured bridge priority of the LAN bridge and the bridge MAC address of the LAN bridge included in the second message. Determine the bridge ID of the LAN bridge.
  • the bridge priority of the LAN bridge locally configured by the first user plane network element will be the same as the bridge priority of the LAN bridge used by the first terminal device, so as to ensure that the bridge identifiers of the LAN bridge determined by the two devices are the same.
  • the bridge priority of the LAN bridge locally configured by the first user plane network element may be set according to the factory configuration of the first terminal device, or determined according to negotiation between the first terminal device and the first user plane network element.
  • the first user plane network element can determine the bridge identifier of the LAN bridge according to the locally configured bridge priority and bridge MAC address.
  • the following describes the specific implementation of the STP election process performed by the first user plane network element in the LAN bridge.
  • the first user plane network element considers the LAN bridge as the root bridge, and the first user plane network element sends a fourth configuration BPDU message through the port of the first user plane network element according to the bridge identifier of the LAN bridge.
  • the value of the bridge ID field is set to the bridge ID of the LAN bridge.
  • the first user plane network element further receives the third configuration BPDU message through the port of the first user plane network element.
  • the first user plane network element also transparently transmits (or forwards) the third configuration BPDU message to the first terminal device through the PDU session between the first terminal device and the first user plane network element. Therefore, the first terminal device can obtain information such as the peripheral devices of the first user plane network element (eg, bridge identifier, port identifier, etc.).
  • the first user plane network element further receives the second configuration BPDU message transparently transmitted by the first terminal device through the PDU session between the first terminal device and the first user plane network element.
  • the second configuration BPDU packet is a BPDU packet received by the port of the first user plane network element. Therefore, the first user plane network element can learn the information (eg, bridge identifier, port identifier, etc.) of the peripheral devices of the first terminal device.
  • the first user plane network element determines the bridge role of the LAN bridge according to the second configuration BPDU, the third configuration BPDU, and the fourth configuration BPDU. Specifically, based on the second configuration BPDU message, the third configuration BPDU message, and the fourth configuration BPDU message, the first user plane network element determines whether the bridge identifier of the LAN bridge where the first user plane network element is located is the smallest in the network. of. In the case where the bridge ID of the LAN bridge is the smallest in the network, the LAN bridge is the root bridge. Otherwise, the LAN bridge is a non-root bridge.
  • a port on one device in the LAN bridge for communicating with another device in the LAN bridge is simply referred to as an internal port.
  • the port on a device in a LAN bridge that is used to communicate with devices that do not belong to the LAN bridge is referred to as an external port for short.
  • the roles of the external ports on each device in the LAN bridge are designated ports, and the port states are all forwarding states.
  • each device in the LAN bridge needs to elect the root port and designated port.
  • the internal ports of the LAN bridge can be set to be blocked to avoid loops inside the LAN bridge.
  • the internal port of the LAN bridge does not participate in the election of the root port and the election of the designated port.
  • the external port For each external port of the LAN bridge, the external port will compare the received configuration BPDU with the configuration BPDU stored by the external port. When the priority of the received configuration BPDUs is lower than that of the configuration BPDUs stored on the port, the external port discards the received configuration BPDUs. If the received configuration BPDU has a higher priority than the configuration BPDU stored by the external port, the external port updates the stored configuration BPDU with the received configuration BPDU, or the external port discards the previously stored configuration. BPDUs, and store the just received configuration BPDUs.
  • Multiple devices in a LAN bridge can exchange configuration BPDUs stored on their respective external ports.
  • the device in the LAN bridge compares the configuration BPDUs stored on each external port in the LAN bridge, and selects the configuration BPDU with the highest priority.
  • the external port storing the configuration BPDU with the highest priority is the root port.
  • All external ports other than the root port in the LAN bridge are set as alternate ports.
  • first user plane network element if there is a root port on the first user plane network element, other external ports except the root port on the first user plane network element are standby ports; or, if the first user plane network element If there is no root port on the network element, all external ports on the first user plane network element are standby ports.
  • the standby port needs to participate in the election of the following designated ports.
  • generating a target configuration BPDU packet for the port based on the configuration BPDU packet stored on the root port may include the following operations:
  • the value of the root bridge identifier field of the target configuration BPDU message is the value of the root bridge identifier field of the configuration BPDU message stored on the root port of the LAN bridge.
  • the value of the root path cost field of the target configuration BPDU is determined according to the local path cost of the root port and the value of the root path cost field in the configuration BPDU message stored on the root port.
  • Operation 3 The bridge identifier field of the target configuration BPDU is set to the BID of the first user plane network element, and the port identifier field is set to the port identifier of the port.
  • the first user plane network element when the root port of the LAN bridge is the port of the first user plane network element, the first user plane network element will set the root port of the LAN bridge and the designated port on the first user plane network element to the forwarding state. . After the first user plane network element elects the root port and the designated port of the LAN bridge, the first user plane network element can set other ports except the root port of the LAN bridge and the designated port on the first user plane network element. is blocked.
  • the first user plane network element will set the designated port on the first terminal device to the forwarding state, and the other ports except the designated port will be set to the forwarding state. Set to blocking state.
  • the session management network element may send a second message to the first user plane network element, so that the first user plane network element will Performs STP election by itself as part of the LAN bridge to avoid loops in the network.
  • a method for avoiding loops includes the following steps:
  • An application function network element receives a third message.
  • the third message includes the first container.
  • the first container includes STP information related to the first terminal device.
  • the STP information related to the first terminal device may include first STP capability information and/or first STP version information.
  • the first STP capability information may be used to indicate whether the first terminal device supports the STP function.
  • the first STP version information may be used to indicate the STP version supported by the first terminal device. It should be understood that, in practical applications, the first STP capability information and the first STP version information may be two separate pieces of information, or may be integrated into one piece of information, which is not limited.
  • the third message may further include the second container.
  • the second container includes STP information related to the first user plane network element.
  • the STP information related to the first user plane network element may include second STP capability information and/or second STP version information.
  • the second STP capability information may be used to indicate whether the first user plane network element supports the STP function.
  • the second STP version information may be used to indicate the STP version supported by the first user plane network element. It should be understood that, in practical applications, the second STP capability information and the second STP version information may be two separate pieces of information, or may be integrated into one piece of information, which is not limited.
  • the third message or the second container may further include the bridge identifier of the LAN bridge, such as bridge priority and/or bridge MAC address.
  • the bridge identifier of the LAN bridge included in the third message or the second container may be a candidate bridge priority provided to the application function network element for reference, rather than the bridge identifier actually used by the LAN bridge.
  • the application function network element can use the third message or the bridge identifier of the LAN bridge included in the second container as the bridge identifier actually used by the LAN bridge; or, the application function network element can also allocate the LAN bridge by itself.
  • the actual bridge ID used This embodiment of the present application does not limit this.
  • the LAN bridge includes a first terminal device and a first user plane network element.
  • the PDU session between the first terminal device and the first user plane network element is not regarded as a port on the first terminal device.
  • the PDU session between the first terminal device and the first user plane network element is not regarded as a port on the first terminal device.
  • the LAN bridge may further include a second terminal device connected to the first user plane network element.
  • the second terminal device and the first terminal device belong to the same group.
  • the LAN bridge may further include a second user plane network element, and the second user plane network element is a user plane network element in the 5G LAN associated with the group to which the first terminal device belongs.
  • the tunnel between the first user plane network element and the second user plane network element is not regarded as a port on the first user plane network element.
  • the tunnel between the first user plane network element and the second user plane network element is not regarded as a port on the second user plane network element.
  • the LAN bridge when the LAN bridge further includes a second user plane network element, the LAN bridge may further include a third terminal device connected to the second user plane network element.
  • the third terminal device may belong to the same group as the first terminal device.
  • the application function network element may learn the relationship between the first terminal device and the first user network element. That is, the application function network element can learn that the first terminal device is connected to the first user plane network element.
  • the third message when the third message only includes the first container and does not include the second container, the third message may also include the identification of the first user plane network element (for example, the device identification, the LAN bridge where the first user plane network element is located). The bridge identifier, etc.), so that the application function network element can know that the first terminal device is connected to the first user plane network element.
  • the identification of the first user plane network element for example, the device identification, the LAN bridge where the first user plane network element is located.
  • the bridge identifier, etc. so that the application function network element can know that the first terminal device is connected to the first user plane network element.
  • the third message may further include an identifier of a group to which the first terminal device belongs.
  • step S401 may be specifically implemented as: the application function network element receives the third message from the session management network element.
  • the application function network element may receive the third message from the session management network element through the policy control function network element or the network open function network element.
  • the session management network element sends the third message to the application function network element through the policy control function network element.
  • the transmission path of the third message may be: session management network element->policy control function network element->application function network element.
  • -> indicates the transmission direction of information.
  • Device 1 -> Device 2 means that information is sent from Device 1 to Device 2.
  • the session management network element sends the third message to the application function network element through the policy control function network element and the network opening function network element.
  • the transmission path of the third message may be: session management network element->policy control function network element->network opening function network element->application function network element.
  • the intermediate network element (such as a policy control function network element or a network opening function network element) that transmits the third message may perform corresponding processing on the third message (for example, modify the name, add or modify the content carried by the third message).
  • the application function network element sends a third container to the first terminal device.
  • the first terminal device receives the third container sent by the application function network element.
  • the third container is used to determine the bridge identifier of the LAN bridge where the first terminal device is located.
  • the third container may include the bridge ID or bridge priority and/or bridge MAC address of the LAN bridge. It should be understood that the bridge identification consists of the bridge priority and the bridge MAC address. Alternatively, the third container may include the bridge identification of the LAN bridge.
  • the third container further includes second indication information.
  • the second indication information is used to instruct the first terminal device to activate the STP function.
  • step S402 may be specifically implemented as: when the third preset condition is satisfied, the application function network element sends the third container to the first terminal device.
  • the third preset condition includes one or more of the following:
  • Condition 3-1 The operator policy information obtained by the application function network element is used to indicate that the STP function is allowed to be activated.
  • the application function network element may acquire operator or third-party policy information from an operation and maintenance management (operation administration and maintenance, OAM) system.
  • OAM operation administration and maintenance
  • the policy information may be applied to the entire operator network, or the operator policy information may be applied to the group to which the first terminal device belongs.
  • Condition 3-2 There are multiple ports for connecting to the data network in the 5GLAN user plane topology associated with the group to which the first terminal device belongs; and/or, there are multiple ports in the 5GLAN user plane topology associated with the group to which the first terminal device belongs. user plane network element.
  • the third message includes indication information for instructing to activate the STP function.
  • Condition 3-4 The first terminal device supports the STP function.
  • the application function management network element may determine whether the first terminal device supports the STP function according to the first STP information.
  • the first terminal device activates the STP function according to the third container.
  • the first terminal device After receiving the third container, acquires the parameters used when activating the STP function. Afterwards, the first terminal device activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first terminal device performs a maintenance process.
  • step S304 for the specific details of the first terminal device performing the STP election process, reference may be made to step S304 in the embodiment shown in FIG. 11 , which will not be repeated here.
  • the application function network element sends the third container to the first terminal device, so that the first terminal device determines the bridge identifier of the LAN bridge where it is located. Further, the first terminal device can participate in the STP election as a part of the LAN bridge to avoid loops in the network.
  • the method for avoiding loops further includes steps S404 - S405 .
  • the application function network element sends a fourth container to the first user plane network element.
  • the first user plane network element receives the fourth container sent by the application function network element.
  • the fourth container can be used to determine the bridge identification BID of the LAN bridge.
  • the fourth container may include the bridge identification or bridge priority and/or bridge MAC address of the LAN bridge. It should be understood that the bridge identification consists of the bridge priority and the bridge MAC address.
  • the fourth container includes the bridge identification of the LAN bridge.
  • the fourth container may include first indication information, where the first indication information is used to instruct the first user plane network element to activate the STP function.
  • first indication information is used to instruct the first user plane network element to activate the STP function.
  • step S405 may be specifically implemented as: when the fourth preset condition is satisfied, the application function network element sends the fourth container to the first user plane network element.
  • the fourth preset condition includes one or more of the following:
  • the policy information of the operator or the third party obtained by the application function network element is used to indicate that the STP function is allowed to be activated.
  • the policy information may be applicable to the entire operator network, or the policy information may be associated with a group to which the first terminal device belongs.
  • Condition 4-2. There are multiple ports for connecting to the data network in the 5GLAN user plane topology associated with the group to which the first terminal device belongs; and/or, there are multiple ports in the 5GLAN user plane topology associated with the group to which the first terminal device belongs. user plane network element.
  • the third message includes indication information for instructing to activate the STP function.
  • Condition 4-4 The first user plane network element supports the STP function.
  • the application function network element may determine whether the first user plane network element supports the STP function according to the second STP capability information.
  • condition 4-1 to condition 4-4 are only examples of the fourth preset condition, and do not constitute a specific limitation.
  • the first user plane network element activates the STP function according to the fourth container.
  • the first user plane network element After receiving the fourth container, acquires the parameters used for activating the STP function. After that, the first user plane network element activates the STP function according to the parameters used when activating the STP function, so as to perform the STP election process. And, after the STP election process, the first user plane network element performs a maintenance process.
  • the first user plane network element may obtain the parameters related to the second port from the session management network element.
  • the parameters related to the second port may include: a port number of the second port, a port priority, and a QoS parameter.
  • the QoS parameter of the second port is used to determine the bandwidth of the second port.
  • the bandwidth of the second port is used to determine the port cost of the second port.
  • the QoS parameters of the second port may include but are not limited to: group (group)-AMBR.
  • step S306 in the embodiment shown in FIG. 12 , which will not be repeated.
  • the application function network element sends the fourth container to the first user plane network element, so that the first user plane network element uses itself as part of the LAN bridge to perform STP election to avoid network A loop appears in the .
  • FIG. 14 The embodiment shown in FIG. 14 will be described in detail below with reference to specific examples.
  • a method for avoiding loops includes the following steps:
  • the first terminal device sends a PDU session establishment request message to a session management network element.
  • the session management network element receives the PDU session establishment request message sent by the first terminal device.
  • the PDU session establishment request message is used to request the establishment of a PDU session.
  • the PDU session establishment request message includes: the first container and the identifier of the group to which the first terminal device belongs.
  • the first container For the specific description of the first container, reference may be made to the above, which will not be repeated here.
  • the session management network element selects the first user plane network element according to the PDU session establishment request message.
  • step S502 may refer to the introduction of step S102, which is not repeated here.
  • the session management network element acquires the second container.
  • the session management network element receives an N4 message sent by the first user plane network element, where the N4 message includes the second container.
  • the N4 message may further include an identifier of the group to which the first terminal device belongs.
  • the N4 message may be an N4 report (report) message or an N4 session response message, which is not limited.
  • the first terminal device when the first terminal device is the first in the group to connect to the first user network element, the first user plane network element The network element sends an N4 message containing the second container.
  • the first user plane network element may display the bridge information (such as bridge priority or bridge MAC When the address), port information, etc. are changed, the N4 message containing the second container is actively sent to the session management network element.
  • the bridge information such as bridge priority or bridge MAC
  • the session management network element sends a third message to the application function network element.
  • the application function network element receives the third message sent by the session management network element.
  • the session management network element may send the third message to the application function network element.
  • the third message sent by the session management network element may include indication information for instructing to activate the STP function.
  • the session management network element sends the third message to the application function network element through the policy control function network element.
  • the transmission path of the third message may be: session management network element->policy control function network element->application function network element.
  • the session management network element sends the third message to the application function network element through the policy control function network element and the network opening function network element.
  • the transmission path of the third message may be: session management network element->policy control function network element->network opening function network element->application function network element.
  • the application function network element sends a fourth message to the session management network element.
  • the session management network element receives the fourth message sent by the application function network element.
  • the fourth message may include the third container.
  • the fourth message may further include a fourth container.
  • the fourth message may further include an identifier of a group to which the first terminal device belongs.
  • the application function network element sends the fourth message to the session management network element through the policy control function network element.
  • the transmission path of the fourth message may be: application function network element->policy control function network element->session management network element.
  • the application function network element sends the fourth message to the session management network element through the policy control function network element and the network open function network element.
  • the transmission path of the fourth message may be: application function network element -> network opening function network element -> policy control function network element -> session management network element.
  • the intermediate network element for example, the policy control function network element or the network opening function network element
  • the intermediate network element may perform corresponding processing on the fourth message (for example, modify the content of the fourth message). name, add or modify the content carried by the fourth message).
  • the session management network element sends the third container to the first terminal device according to the fourth message.
  • the first terminal device activates the STP function according to the third container.
  • the following steps S508-S509 may also be performed.
  • the session management network element sends a fourth container to the first user plane network element according to the fourth message.
  • the session management network element may also send parameters related to the second port to the first user plane network element.
  • the parameters related to the second port may include: a port number of the second port, a port priority, and a QoS parameter.
  • the parameters related to the second port and the fourth container may be encapsulated in the same N4 message, or encapsulated in different N4 messages and sent separately.
  • the first user plane network element activates the STP function according to the fourth container.
  • the session management network element is responsible for forwarding the container between the first terminal device and the application function network element, and the container between the first user plane network element and the application function network element. Therefore, the application function network element can make the first terminal device activate the STP function through the third container, and make the first user plane network element activate the STP function through the fourth container.
  • UE1, UE2 and UPF1 can form a LAN bridge to participate in STP election.
  • the port for communication between UE1 and UE2 is the internal port of the LAN bridge, so the port used for communication with UE2 on UE1 will be set to a blocked state, and the port used to communicate with UE1 on UE2 will be set to be blocked. state, so the link between UE1 and UE2 will be logically blocked.
  • UPF1 can transparently transmit the configuration BPDUs it receives from DN1 to UE1 and UE2, and UE2 can transparently transmit the configuration BPDUs it receives from UE3 or UE4 to UPF1 and UE1.
  • a LAN bridge formed by UE1, UE2 and UPF1 is elected as the root bridge, so all external ports of the LAN bridge are set to DP. That is, the port on UPF1 for communicating with DN1 is set as DP, the port on UE2 for communicating with UE3 is set as DP, and the port on UE2 for communicating with UE4 is set as DP.
  • the port on DN1 for communicating with UPF1 is elected as RP
  • the port on DN1 for communicating with UE4 is elected as AP
  • the port on UE3 used to communicate with UE2 is elected as RP.
  • the port on UE4 for communicating with DN1 is elected as AP
  • the port on UE4 for communicating with UE2 is elected as RP.
  • UE1, UE2 and UPF1 can form a LAN bridge 1 to participate in STP election.
  • UE5, UE6 and UPF can form a LAN bridge 2 to participate in STP election.
  • the N19 tunnel between UPF2 and UPF1 is regarded as a port on both UPF2 and UPF1.
  • the port for communication between UE1 and UE2 is the internal port of LAN bridge 1, so the port on UE1 for communicating with UE2 will be set to a blocked state, and the port on UE2 for communicating with UE1 will be set to Blocked state, whereby the link between UE1 and UE2 will be logically blocked.
  • UPF1 can transparently transmit the configuration BPDUs it received from DN1 or UPF2 to UE1 and UE2, and UE2 can transparently transmit the configuration it received from UE6, UE3 or UE4 to UPF1 and UE1 BPDU message.
  • UPF2 can transparently transmit the configuration BPDUs it receives from DN1 or UPF1 to UE5 and UE6, and UE6 can transparently transmit the configuration BPDUs it receives from UE2 to UPF2 and UE5.
  • LAN bridge 2 is elected as the root bridge, so that all external ports of LAN bridge 2 are set to DP. That is, the port of UPF2 for communicating with UPF1 is set to DP, the port of UPF2 for communicating with DN1 is set to DP, and the port of UE6 for communicating with UE2 is set to DP.
  • the port on UPF1 for communicating with UPF2 is set as RP, and the port on UPF1 for communicating with DN1 is set as DP.
  • the port on UE2 for communicating with UE3 is set to DP
  • the port on UE2 for communicating with UE4 is set as DP
  • the port on UE2 for communicating with UE6 is set as AP.
  • the port on DN1 for communicating with UPF1 is elected as AP, and the port on DN1 for communicating with UPF2 is elected as RP.
  • the port on UE3 used to communicate with UE2 is elected as RP.
  • the port on UE4 for communicating with DN1 is elected as AP, and the port on UE4 for communicating with UE2 is elected as RP.
  • user plane NEs need to activate the STP function to prevent loops in the network.
  • user plane network elements may not activate the STP function to reduce the number of BPDUs received and reduce the pressure on user plane network elements to process packets. Therefore, it is necessary to manage the deactivation of the STP function of the user plane network element accordingly.
  • an embodiment of the present application provides a method for managing the STP function. As shown in Figure 17, the method includes the following steps:
  • the session management network element sends third indication information to the first user plane network element.
  • the first user plane network element receives the third indication information sent by the session management network element.
  • the third indication information is used to indicate deactivation of the STP function. Specifically, the third indication information is used to instruct the first user plane network element to deactivate the STP function.
  • the third indication information is used to instruct the first user plane network element to deactivate the STP function for the group to which the first terminal device belongs.
  • the third indication information includes the identifier of the group to which the first terminal device belongs.
  • the third indication information may be carried in the N4 message.
  • the session management network element determines that the first user plane network element does not provide 5G LAN services for any terminal device in the group to which the first terminal device belongs, the session management network element sends the first user plane network element to the first user plane network element.
  • the element sends the third indication information.
  • the session management network element sends third indication information to the first user plane network element.
  • the first user plane network element deactivates the STP function according to the third indication information.
  • the deactivation of the STP function by the first user plane network element may be implemented as follows: the first user plane network element sets all of the first port, the second port and the third port to a disabled state.
  • the first user plane network element may deactivate the STP function according to the instruction of the session management network element. Therefore, the first user plane network element can avoid continuously receiving unnecessary BPDUs.
  • FIG. 17 may be used in combination with any one of the embodiments shown in FIG. 5 , FIG. 6 , FIG. 9 , FIG. 11 , FIG. 12 , FIG. 13 , FIG. 14 or FIG. 15 .
  • activating the STP function may be replaced with concepts such as “running the STP” and “enabling the STP function”.
  • deactivate the STP function can be replaced with concepts such as “stop running STP”, “deactivate the STP function”, and so on.
  • FIG. 5 , FIG. 6 , FIG. 11 , FIG. 12 , or FIG. 15 only describe a part of the steps in the PDU session establishment process. It should be understood that the PDU session establishment procedure may further include other steps. For other steps in the PDU session establishment process, reference may be made to the description in the prior art, which will not be repeated here.
  • a port may refer to a physical port or a logical port, which is not limited.
  • the communication apparatus for example, a session management network element, an application function network element, a first terminal device, or a first user plane network element
  • the communication apparatus includes a hardware structure and/or software corresponding to each function. module.
  • the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is performed by hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of the technical solutions of the embodiments of the present application.
  • the communication device may be divided into functional units according to the foregoing method examples.
  • each functional unit may be divided corresponding to each function, or two or more functions may be integrated into one processing unit.
  • the above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units. It should be noted that the division of units in the embodiments of the present application is illustrative, and is only a logical function division, and other division methods may be used in actual implementation.
  • a communication apparatus provided by an embodiment of the present application includes a processing module 101 and a communication module 102 .
  • the processing module 101 is configured to support the session management network element to perform step S102 in FIG. 5 , step S201 in FIG. 9 , and/or the session management network element. Additional processing operations that need to be performed.
  • the communication module 102 is used to support the session management network element to perform steps S101 and S103 in FIG. 5, step S105 in FIG. 6, steps S202, S204 and S206 in FIG. 9, steps S301 and S303 in FIG. 11, and steps S301 and S303 in FIG. 12. step S305, steps S504-S506 and S508 in FIG. 15, step S601 in FIG. 17, and/or other communication operations that the session management network element needs to perform.
  • the processing module 101 is configured to support the first user plane network element to perform step S104 in FIG. 5 , steps S203 and S207 in FIG. 9 , Step S306 in FIG. 12 , step S405 in FIG. 14 , step S509 in FIG. 15 , step S602 in FIG. 17 , and/or other processing operations that need to be performed by the first user plane network element.
  • the communication module 102 is configured to support the first user plane network element to perform step S103 in FIG. 5 , steps S202 and S206 in FIG. 9 , step S305 in FIG. 12 , step S404 in FIG. 14 , step S508 in FIG. 15 , Step S601 in FIG. 17 , and/or other communication operations that need to be performed by the first user plane network element.
  • the processing module 101 is configured to support the first terminal device to perform step S106 in FIG. 6 , step S205 in FIG. 9 , and step S304 in FIG. 11 . , step S403 in FIG. 13 , step S507 in FIG. 15 , and/or other processing operations that need to be performed by other first terminal devices.
  • the communication module 102 is used to support the first terminal device to perform step S101 in FIG. 5 , step S105 in FIG. 6 , step S204 in FIG. 9 , steps S301 and S303 in FIG. 11 , step S402 in FIG. 13 , and step S402 in FIG. 15 in steps S501 and S506, and/or other communication operations that need to be performed by the first terminal device.
  • the processing module 101 is configured to support the application function network element to perform processing operations (eg, generating a third container, generating a fourth container, etc.).
  • the communication module 102 is used to support the application function network element to perform steps S401-S402 in FIG. 13 , step S404 in FIG. 14 , steps S504 - S505 in FIG. 15 , and/or other communication operations that the application function network element needs to perform.
  • the communication device may further include a storage module 103 for storing program codes and data of the communication device, and the data may include but not limited to original data or intermediate data.
  • the processing module 101 may be a processor or a controller, such as a CPU, a general-purpose processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other Programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It may implement or execute the various exemplary logical blocks, modules and circuits described in connection with this disclosure.
  • a processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.
  • the communication module 102 may be a communication interface, a transceiver or a transceiver circuit, etc., where the communication interface is a general term, and in a specific implementation, the communication interface may include multiple interfaces, for example, may include: an interface between a base station and a terminal and/or or other interfaces.
  • the storage module 103 may be a memory.
  • the processing module 101 is a processor
  • the communication module 102 is a communication interface
  • the storage module 103 is a memory
  • the communication device involved in the embodiment of the present application may be as shown in FIG. 19 .
  • the communication device includes: a processor 201 , a communication interface 202 , and a memory 203 .
  • the communication device may further include a bus 204 .
  • the communication interface 202, the processor 201 and the memory 203 can be connected to each other through a bus 204; the bus 204 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus etc.
  • the bus 204 can be divided into an address bus, a data bus, a control bus, and the like. For ease of presentation, only one thick line is shown in FIG. 19, but it does not mean that there is only one bus or one type of bus.
  • the embodiment of the present application further provides a computer program product carrying computer instructions, when the computer instructions are executed on the computer, the computer is made to execute the method described in the foregoing embodiments.
  • an embodiment of the present application further provides a computer-readable storage medium, where the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer executes the methods described in the foregoing embodiments.
  • an embodiment of the present application further provides a chip, including: a processing circuit and a transceiver pin, where the processing circuit and the transceiver pin are used to implement the method introduced in the foregoing embodiment.
  • the processing circuit is used for executing the processing actions in the corresponding method
  • the transceiver pins are used for executing the actions of receiving/transmitting in the corresponding method.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server, or data center Transmission to another website site, computer, server or data center via wired (eg coaxial cable, optical fiber, Digital Subscriber Line, DSL) or wireless (eg infrared, wireless, microwave, etc.) 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, data center, etc., that includes one or more available media integrated.
  • the available media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, Digital Video Disc (DVD)), or semiconductor media (eg, Solid State Disk (SSD)) Wait.
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical or other forms.
  • the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple devices. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each functional unit may exist independently, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units.
  • the present application can be implemented by means of software plus necessary general-purpose hardware, and of course hardware can also be used, but in many cases the former is a better implementation manner .
  • the technical solutions of the present application can be embodied in the form of software products in essence, or the parts that make contributions to the prior art.
  • the computer software products are stored in a readable storage medium, such as a floppy disk of a computer. , a hard disk or an optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application.

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Abstract

本申请提供一种避免环路的方法及装置，涉及通信技术领域，用于在5GLAN与存量LAN互通的场景下，避免网络中出现环路。该方法包括以下步骤：会话管理网元接收第一终端设备发送的PDU会话建立请求消息；所述会话管理网元根据所述PDU会话建立请求消息，选择第一用户面网元；所述会话管理网元向所述第一用户面网元发送第一指示信息，所述第一指示信息用于指示激活STP功能。

Description

避免环路的方法及装置
本申请要求于2020年12月31日提交国家知识产权局、申请号为202011628915.9、申请名称为“避免环路的方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及避免环路的方法及装置。
背景技术
5G本地局域网(local area network，5GLAN)服务是目前的5G网络提供的一个服务，主要应用于家庭通信，企业办公，工厂制造，车联网，电网改造和公安机关等。5GLAN服务能够为一组终端设备中的两个或者多个终端设备提供互联网协议(internet protocol，IP)类型或者非IP类型(如以太类型)的私有通信。比如，基于5GLAN服务，工厂中的设备组成一个群组，不同设备之间可以相互发送以太数据包；或者，企业中一个部门中的雇员的办公设备(如手机，计算机或笔记本电脑等)组成一个群组，不同办公设备之间可以互相发送IP数据包，等等。5GLAN服务可以为群组成员提供广播数据的转发，例如一个终端设备所发送的广播报文转发给组中的其他终端设备。
在5GLAN和存量LAN互通时，终端设备到用户面网元的PDU会话可以认为是交换机之间的链路。从而，在5GLAN和存量LAN所构成的网络中可能存在冗余链路，形成环路。
示例性的，如图1所示，5GLAN包括UPF1和UPF2，UPF1连通LAN#1以及LAN#2，UPF2连通LAN#2和LAN#3。可见，网络中存在多个环路，例如UPF1、LAN#1以及LAN#2之间存在的环路1，UPF2、LAN#2和LAN#3之间存在的环路2。
广播报文会由于网络中存在环路而出现增生和无限循环的现象，影响网络的正常通信。因此，在5GLAN和存量LAN互通的场景下，如何避免环路，是亟待解决的技术问题。
发明内容
本申请提供一种避免环路的方法及装置，用于在5GLAN和存量LAN互通的场景下，避免5GLAN和存量LAN所构成的网络出现环路。
第一方面，提供一种避免环路的方法，包括：会话管理网元接收来自第一终端设备的协议数据单元(protocol data unit，PDU)会话建立请求消息；会话管理网元根据PDU会话建立请求消息，选择第一用户面网元；会话管理网元向第一用户面网元发送第一指示信息，第一指示信息用于指示激活生成树协议(spanning tree protocol，STP)功能。
基于上述技术方案，在第一终端设备建立PDU会话接入5GLAN的场景下，会话管理网元通过向第一用户面网元发送第一指示信息，以使得第一用户面网元激活STP功能，从而避免网络中出现环路，保证网络的正常通信。
一种可能的设计中，第一指示信息用于指示激活STP功能，包括：第一指示信息 用于指示针对第一终端设备所属群组激活STP功能。
一种可能的设计中，第一指示信息包括第一终端设备所属群组的标识。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第一指示信息承载于N4接口消息中。
一种可能的设计中，该方法还包括：会话管理网元向第一用户面网元发送用于配置第一用户面网元激活STP功能的参数。基于该设计，可以间接地实现对生成树的拓扑结构的管理。
一种可能的设计中，用于配置第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥媒体接入控制(media access control，MAC)地址、第一端口的优先级、第一端口的端口号、第二端口的端口号、第二端口的优先级、第三端口的端口号、或第三端口的优先级；其中，第一端口为第一用户面网元上PDU会话对应的端口，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，会话管理网元向第一用户面网元发送第一指示信息，包括：会话管理网元根据第一终端设备所属群组的标识，获取运营商策略信息；在运营商策略信息用于指示允许激活STP功能的情况下，会话管理网元向第一用户面网元发送第一指示信息。基于该设计，可以通过运营商策略信息来控制会话管理网元是否发送第一指示信息，进而实现对第一用户面网元是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一用户面网元发送第一指示信息，包括：会话管理网元根据第一终端设备所属群组的标识，从统一数据管理网元获取与第一终端设备所属群组的签约信息；在签约信息包括用于指示激活STP功能的指示信息的情况下，会话管理网元向第一用户面网元发送第一指示信息。基于该设计，可以通过签约信息来控制会话管理网元是否发送第一指示信息，进而实现对第一用户面网元是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一用户面网元发送第一指示信息，包括：会话管理网元从策略控制功能网元获取第一终端设备的策略与计费控制规则；在策略与计费控制规则包括用于指示激活STP功能的指示信息的情况下，会话管理网元向第一用户面网元发送第一指示信息。基于该设计，可以通过策略与计费控制规则来控制会话管理网元是否发送第一指示信息，进而实现对第一用户面网元是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一用户面网元发送第一指示信息，包括：会话管理网元从本地获取第一终端设备所属群组相关的5GLAN的用户面拓扑；在5GLAN的用户面拓扑存在多个用于与数据网络连接的端口，或者5GLAN的用户面拓扑中存在多个用户面网元的情况下，会话管理网元向第一用户面网元发送第一指示信息。基于该设计，会话管理网元发送第一指示信息的操作能够符合5GLAN的用户面拓扑的客观条件，保证5GLAN与存量LAN的正常通信。
一种可能的设计中，该方法还包括：会话管理网元向第一终端设备发送第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。基于该设计，第一终端设备可以根据第二指示信息，激活STP功能，以避免网络中出现环路。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，该方法还包括：会话管理网元向第一终端设备发送用于配置第一终端设备激活STP功能的参数。基于该设计，可以间接实现对生成树的拓扑的管理。
一种可能的设计中，用于配置第一终端设备激活STP功能的参数包括以下一项或者多项：第四端口的端口号或第四端口的优先级，第四端口为第一终端设备上PDU会话对应的端口。
一种可能的设计中，会话管理网元向第一终端设备发送第二指示信息，包括：会话管理网元获取第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能；当第一STP能力信息用于指示第一终端设备支持STP功能时，会话管理网元向第一终端设备发送第二指示信息。基于该设计，可以避免第一终端设备的配置与会话管理网元的指示相矛盾的情况出现。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息。
一种可能的设计中，该方法还包括：会话管理网元从移动管理网元获取第一STP能力信息。应理解，移动管理网元可以从第一终端设备获取第一STP能力信息。
一种可能的设计中，该方法还包括：在第一用户面网元不为第一终端设备所属群组中的任意一个终端设备提供服务的情况下，会话管理网元向第一用户面网元发送第三指示信息，第三指示信息用于指示去激活STP功能。基于该设计，可以使得第一用户面网元无需接收不必要的BPDU报文，以减轻第一用户面网元处理报文的压力。
第二方面，提供一种避免环路的方法，包括：第一用户面网元接收会话管理网元发送的第一指示信息，第一指示信息用于指示激活STP功能；第一用户面网元根据第一指示信息，激活STP功能。
基于上述技术方案，第一用户面网元根据第一指示信息，激活STP功能，可以避免网络中出现环路。
一种可能的设计中，第一指示信息用于指示激活STP功能，包括：第一指示信息用于指示针对第一终端设备所属群组激活STP功能。
一种可能的设计中，第一指示信息包括第一终端设备所属群组的标识。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第一指示信息承载于N4接口消息中。
一种可能的设计中，该方法还包括：第一用户面网元接收会话管理网元发送的用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，用于配置第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥媒体接入控制MAC地址、第一端口的优先级、第一端口的端口号、第二端口的端口号、第二端口的优先级、第三端口的端口号、或第三端口的优先级；其中，第一端口为第一用户面网元上PDU会话对应的端口，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，该方法还包括：第一用户面网元接收会话管理网元发送的第三指示信息，第三指示信息用于指示去激活STP功能；第一用户面网元根据第三指示 信息，去激活STP功能。
第三方面，提供一种避免环路的方法，包括：第一终端设备向会话管理网元发送PDU会话建立请求消息；第一终端设备接收会话管理网元发送的第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
基于上述技术方案，在第一终端设备建立PDU会话接入5GLAN的情况下，第一终端设备接收会话管理网元发送的第二指示信息，并根据第二指示信息激活STP功能，从而可以避免网络中出现环路。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，该方法还包括：第一终端设备接收会话管理网元发送的用于配置第一终端设备激活STP功能时使用的参数。
一种可能的设计中，用于配置第一终端设备激活STP功能时使用的参数包括以下参数中的一项或者多项：第四端口的端口号、或第四端口的优先级，第四端口为第一终端设备上PDU会话对应的端口。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP。
一种可能的设计中，该方法还包括：第一终端设备在注册流程中向移动管理网元发送第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能。基于该设计，在后续流程中，移动管理网元可以向会话管理网元发送第一STP能力信息。
第四方面，提供一种避免环路的方法，包括：会话管理网元接收来自第一终端设备的PDU会话建立请求消息；会话管理网元根据PDU会话建立请求消息，选择第一用户面网元；会话管理网元向第一终端设备发送第一消息，第一消息用于确定局域网桥LAN bridge的桥标识，LAN bridge包括第一用户面网元以及第一终端设备。
基于上述技术方案，在第一终端设备建立PDU会话接入5GLAN的情况下，会话管理网元通过向第一终端设备发送第一消息，以使得第一终端设备和第一用户面网元构成一个LAN bridge来运行STP，从而避免网络中出现环路。
同时，将第一终端设备和第一用户面网元构成一个LAN bridge，可以减少网络中的LAN bridge(或者说交换机)的数量，简化网络的拓扑。
一种可能的设计中，第一消息包括LAN bridge的桥优先级和/或桥MAC地址。或者，第一消息包括LAN bridge的桥标识。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。应理解，将多个终端设备和用户面网元作为一个LAN bridge，可以使得终端设备的接入/退出只会影响到一个LAN bridge上的端口状态，从而在较多数量的终端设备的接入和/或退出的过程中，可以简化拓扑管理，以及使得生成树可以快速收敛。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一消息包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，该方法还包括：会话管理网元向第一用户面网元发送第二消 息，第二消息用于确定LAN bridge的桥标识。基于该设计，会话管理网元通过向第一用户面网元发送第一消息，以使得第一终端设备和第一用户面网元构成一个LAN bridge来运行STP，从而避免网络中出现环路。
一种可能的设计中，第二消息包括LAN bridge的桥优先级和/或桥MAC地址。或者，第二消息包括LAN bridge的桥标识。
一种可能的设计中，第二消息还包括第一指示信息，第一指示信息用于指示激活STP功能。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第二消息还包括第一终端设备所属群组的标识。
一种可能的设计中，该方法还包括：会话管理网元向第一用户面网元发送用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，参数包括以下一项或者多项：第二端口的端口号、第二端口的优先级、第二端口的QoS参数、第三端口的端口号或第三端口的优先级，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，会话管理网元向第一终端设备发送第一消息，包括：会话管理网元根据第一终端设备所属群组的标识，获取与第一终端设备所属群组关联的运营商策略信息；当运营商策略信息用于指示激活STP功能时，会话管理网元向第一终端设备发送第一消息。基于该设计，可以通过运营商策略信息来控制会话管理网元是否发送第一消息，进而实现对第一终端设备是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一终端设备发送第一消息，包括：会话管理网元根据第一终端设备所属群组的标识，获取与第一终端设备所属群组的签约信息；在签约信息包括用于指示激活STP功能的指示信息的情况下，会话管理网元向第一终端设备发送第一消息。基于该设计，可以通过签约信息来控制会话管理网元是否发送第一消息，进而实现对第一终端设备是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一终端设备发送第一消息，包括：会话管理网元从策略控制功能网元获取第一终端设备的策略与计费控制规则；在策略与计费控制规则包括用于指示激活STP功能的指示信息的情况下，会话管理网元向第一终端设备发送第一消息。基于该设计，可以通过策略与计费控制规则来控制会话管理网元是否发送第一消息，进而实现对第一终端设备是否激活STP功能的间接管理。
一种可能的设计中，会话管理网元向第一终端设备发送第一消息，包括：会话管理网元从本地获取第一终端设备所属群组相关的5GLAN的用户面拓扑；在5GLAN的用户面拓扑存在多个用于与数据网络连接的端口，或者5GLAN的用户面拓扑中存在多个用户面网元的情况下，会话管理网元向第一终端设备发送第一消息。基于该设计，会话管理网元发送第一消息的操作能够符合5GLAN的用户面拓扑的客观条件，保证5GLAN与存量LAN的正常通信。
一种可能的设计中，会话管理网元向第一终端设备发送第一消息，包括：会话管理网元获取第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能；当第一STP能力信息用于指示第一终端设备支持STP功能时，会话管理网 元向第一终端设备发送第一消息。基于该设计，可以避免第一终端设备的配置与会话管理网元的指示相矛盾的情况出现。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息。
另一种可能的设计中，该方法还包括：会话管理网元从移动管理网元获取第一STP能力信息。应理解，移动管理网元可以在第一终端设备的注册流程中接收第一终端设备发送的第一STP能力信息。
第五方面，提供一种避免环路的方法，包括：第一用户面网元接收第二消息，第二消息用于确定第一用户面网元所在的LAN bridge的桥标识，LAN bridge包括第一用户面网元以及连接到第一用户面网元的第一终端设备；第一用户面网元根据第二消息，激活STP功能。
基于该设计，会话管理网元通过向第一用户面网元发送第一消息，以使得第一终端设备和第一用户面网元构成一个LAN bridge来运行STP，从而避免网络中出现环路。
一种可能的设计中，第二消息包括LAN bridge的桥优先级和/或桥MAC地址。或者，第二消息包括LAN bridge的桥标识。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第二消息还包括第一指示信息，第一指示信息用于指示激活STP功能。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第二消息还包括第一终端设备所属群组的标识。
一种可能的设计中，该方法还包括：第一用户面网元接收会话管理网元发送的用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，参数包括以下一项或者多项：第二端口的端口号、第二端口的优先级、第二端口的QoS参数、第三端口的端口号或第三端口的优先级，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，该方法还包括：第一用户面网元通过第一用户面网元的端口发送第四配置BPDU报文，第四配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
一种可能的设计中，该方法还包括：第一用户面网元通过第一用户面网元的端口接收第三配置BPDU报文；第一用户面网元通过第一终端设备和第一用户面网元之间的PDU会话，向第一终端设备发送第三配置BPDU报文。基于该设计，可以使得第一终端设备获知第一用户面网元连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一用户面网元通过PDU会话，接收第一终端设备发送的第二配置BPDU报文，第二配置BPDU报文是第一终端设备的端口接收到的配置BPDU报文。基于该设计，可以使得第一用户面网元获知第一终端设备连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一用户面网元根据第四配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN bridge的桥角色，桥角色为 根桥或者非根桥。
第六方面，提供一种避免环路的方法，包括：第一终端设备向会话管理网元发送PDU会话建立请求消息，PDU会话建立请求消息用于请求建立PDU会话；第一终端设备接收会话管理网元发送的第一消息，第一消息用于确定LAN bridge的桥标识，LAN bridge包括第一终端设备以及第一终端设备连接到的第一用户面网元。
基于上述技术方案，在第一终端设备建立PDU会话接入5GLAN的情况下，第一终端设备接收会话管理网元发送的第一消息，从而第一终端设备和第一用户面网元构成一个LAN bridge来运行STP，从而避免网络中出现环路。
一种可能的设计中，第一消息包括LAN bridge的桥标识。或者，第一消息包括LAN bridge的桥优先级和/或桥MAC地址。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一消息还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，该方法还包括：第一终端设备根据LAN bridge的桥标识，通过第一终端设备的端口发送第一配置BPDU报文，第一配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
一种可能的设计中，该方法还包括：第一终端设备通过第一终端设备的端口接收第二配置BPDU报文；第一终端设备通过PDU会话，向第一用户面网元发送第二配置BPDU报文。基于该设计，可以使得第一用户面网元获知第一终端设备连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：当第二配置BPDU报文的根桥标识字段的取值为LAN Bridge的桥标识时，第一终端设备将接收到第二配置BPDU报文的端口设置为阻塞状态。基于该设计，第一终端设备可以识别出LAN bridge的内部端口，以及将内部端口设置为阻塞状态，以避免LAN bridge内部出现环路。
一种可能的设计中，该方法还包括：第一终端设备通过PDU会话，接收第一用户面网元发送的第三配置BPDU报文，第三配置BPDU报文是第一用户面网元的端口接收到的配置BPDU报文。基于该设计，可以使得第一终端设备获知第一用户面网元连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一终端设备根据第一配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN bridge的桥角色，桥角色为根桥或者非根桥。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP。
一种可能的设计中，该方法还包括：第一终端设备在注册流程中向移动管理网元发送第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能。基于该设计，在后续流程中，移动管理网元可以向会话管理网元发送第一STP能力信息。
第七方面，提供一种避免环路的方法，包括：应用功能网元接收第三消息，第三消息包括第一容器，第一容器包括第一终端设备相关的STP信息；应用功能网元根据第三消息，向第一终端设备发送第三容器，第三容器用于确定LAN bridge的桥标识，LAN bridge包括第一终端设备和第一终端设备连接到的第一用户面网元。
基于上述技术方案，应用功能网元通过接收第三消息，获取第一终端设备相关的STP信息，进而间接获知第一终端设备通过建立PDU会话接入5GLAN。之后，应用功能网元通过向第一终端设备发送第三容器，以使得第一终端设备和第一用户面网元构成一个LAN bridge来运行STP，从而避免网络中出现环路。
一种可能的设计中，第三容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第三容器包括LAN bridge的桥标识。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一终端设备相关的STP信息包括第一STP能力信息和/或第一STP版本信息，第一STP能力信息用于指示第一终端设备是否支持STP功能，第一STP版本信息用于指示第一终端设备支持的STP版本。
一种可能的设计中，第三容器还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第三消息还包括第一终端设备所属群组的标识。
一种可能的设计中，第三消息还包括第二容器，第二容器包括第一用户面网元相关的STP信息。
一种可能的设计中，第一用户面网元相关的STP信息包括第二STP能力信息和/或第二STP版本信息，第二STP能力信息用于指示第一用户面网元是否支持STP功能，第二STP版本信息用于指示第一用户面网元支持的STP版本。
一种可能的设计中，该方法还包括：应用功能网元向第一用户面网元发送第四容器，第四容器用于确定LAN bridge的桥标识。
一种可能的设计中，第四容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第四容器包括LAN bridge的桥标识。
一种可能的设计中，第四容器还包括第一指示信息，第一指示信息用于指示激活STP功能。
第八方面，提供一种避免环路的方法，包括：第一终端设备向应用功能网元发送第一容器，第一容器包括第一终端设备相关的STP信息；第一终端设备接收应用功能网元发送的第三容器，第三容器用于确定LAN bridge的桥标识，LAN bridge包括第一终端设备和第一终端设备连接到的第一用户面网元；第一终端设备根据第三容器，激活STP功能。
基于上述技术方案，第一终端设备接收应用功能网元发送的第三容器，从而激活STP功能，以避免网络中出现环路。并且，基于该技术方案，第一终端设备会和第一用户面网元作为一个LAN bridge来运行STP。应理解，将第一终端设备和第一用户面网元构成一个LAN bridge，可以减少网络中的LAN bridge(或者说交换机)的数量，简化网络的拓扑。
一种可能的设计中，第三容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第三容器包括LAN bridge的桥标识。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。应理解，将多个终端设备和用户面网元作为一个LAN bridge，可以使得终端设备的接入/退出只会影响到一个LAN bridge上的端口状态，从而在较多数量的终端设备的接入和/或退出的过程中，可以简化拓扑管理，以及使得生成树可以快速收敛。
一种可能的设计中，第一终端设备相关的STP信息包括第一STP能力信息和/或第一STP版本信息，第一STP能力信息用于指示第一终端设备是否支持STP功能，第一STP版本信息用于指示第一终端设备支持的STP版本。
一种可能的设计中，第三容器还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，该方法还包括：第一终端设备根据LAN bridge的桥标识，通过第一终端设备的端口发送第一配置BPDU报文，第一配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
一种可能的设计中，该方法还包括：第一终端设备通过第一终端设备的端口接收第二配置BPDU报文。第一终端设备通过PDU会话，向第一用户面网元发送第二配置BPDU报文。基于该设计，可以使得第一用户面网元获知第一终端设备连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：当第二配置BPDU报文的根桥标识字段的取值为LAN bridge的桥标识时，第一终端设备将接收到第二配置BPDU报文的端口设置为阻塞状态。基于该设计，第一终端设备可以识别出LAN bridge的内部端口，以及将内部端口设置为阻塞状态，以避免LAN bridge内部出现环路。
一种可能的设计中，该方法还包括：第一终端设备通过PDU会话，接收第一用户面网元发送的第三配置BPDU报文，第三配置BPDU报文是第一用户面网元的端口接收到的配置BPDU报文。基于该设计，可以使得第一终端设备获知第一用户面网元连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一终端设备根据第一配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN bridge的桥角色，桥角色为根桥或者非根桥。
第九方面，提供一种避免环路的方法，包括：第一用户面网元接收应用功能网元发送的第四容器，第四容器用于确定LAN bridge的桥标识，LAN bridge包括第一用户面网元与连接到第一用户面网元的第一终端设备；第一用户面网元根据第四容器，激活STP功能。
基于上述技术方案，第一用户面网元接收应用功能网元发送的第四容器，从而激活STP功能，以避免网络中出现环路。并且，基于该技术方案，第一终端设备会和第一用户面网元作为一个LAN bridge来运行STP。应理解，将第一终端设备和第一用户面网元构成一个LAN bridge，可以减少网络中的LAN bridge(或者说交换机)的数量， 简化网络的拓扑。
一种可能的设计中，第四容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第四容器内包括LAN bridge的桥标识。
一种可能的设计中，LAN bridge还包括连接到第一用户面网元的第二终端设备。应理解，将多个终端设备和用户面网元作为一个LAN bridge，可以使得终端设备的接入/退出只会影响到一个LAN bridge上的端口状态，从而在较多数量的终端设备的接入和/或退出的过程中，可以简化拓扑管理，以及使得生成树可以快速收敛。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第四容器还包括第一指示信息，第一指示信息用于指示第一用户面网元激活STP功能。
一种可能的设计中，该方法还包括：第一用户面网元向会话管理网元发送第二容器，第二容器包括第一用户面网元相关的STP信息。
一种可能的设计中，第一用户面网元相关的STP信息包括第二STP能力信息和/或第二STP版本信息，第二STP能力信息用于指示第一用户面网元是否支持STP功能，第二STP版本信息用于指示第一用户面网元支持的STP版本。
一种可能的设计中，该方法还包括：第一用户面网元根据LAN bridge的桥标识，通过第一用户面网元的端口发送第四配置BPDU报文，第四配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
一种可能的设计中，该方法还包括：第一用户面网元通过第一用户面网元的端口接收第三配置BPDU报文；第一用户面网元通过第一终端设备和第一用户面网元之间的PDU会话，向第一终端设备发送第三配置BPDU报文。基于该设计，可以使得第一终端设备获知第一用户面网元连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一用户面网元通过PDU会话，接收第一终端设备发送的第二配置BPDU报文，第二配置BPDU报文是第一终端设备的端口接收到的配置BPDU报文。基于该设计，可以使得第一用户面网元获知第一终端设备连接的设备的信息(例如桥标识、端口标识等)。
一种可能的设计中，该方法还包括：第一用户面网元根据第四配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN bridge的桥角色，桥角色为根桥或者非根桥。
第十方面，提供一种通信装置，包括处理模块和通信模块。通信模块，用于接收来自第一终端设备的PDU会话建立请求消息。处理模块，用于根据PDU会话建立请求消息，选择第一用户面网元。通信模块，还用于向第一用户面网元发送第一指示信息，第一指示信息用于指示激活STP功能。
一种可能的设计中，第一指示信息用于指示激活STP功能，包括：第一指示信息用于指示针对第一终端设备所属群组激活STP功能。
一种可能的设计中，第一指示信息包括第一终端设备所属群组的标识。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第一指示信息承载于N4接口消息中。
一种可能的设计中，通信模块，还用于向第一用户面网元发送用于配置第一用户 面网元激活STP功能的参数。
一种可能的设计中，用于配置第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥媒体接入控制(media access control，MAC)地址、第一端口的优先级、第一端口的端口号、第二端口的端口号、第二端口的优先级、第三端口的端口号、或第三端口的优先级；其中，第一端口为第一用户面网元上PDU会话对应的端口，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，通信模块，具体用于根据第一终端设备所属群组的标识，获取运营商策略信息；在运营商策略信息用于指示允许激活STP功能的情况下，向第一用户面网元发送第一指示信息。
一种可能的设计中，通信模块，具体用于根据第一终端设备所属群组的标识，从统一数据管理网元获取与第一终端设备所属群组的签约信息；在签约信息包括用于指示激活STP功能的指示信息的情况下，向第一用户面网元发送第一指示信息。
一种可能的设计中，通信模块，具体用于从策略控制功能网元获取第一终端设备的策略与计费控制规则；在策略与计费控制规则包括用于指示激活STP功能的指示信息的情况下，向第一用户面网元发送第一指示信息。
一种可能的设计中，通信模块，具体用于从本地获取第一终端设备所属群组相关的5GLAN的用户面拓扑；在5GLAN的用户面拓扑存在多个用于与数据网络连接的端口，或者5GLAN的用户面拓扑中存在多个用户面网元的情况下，向第一用户面网元发送第一指示信息。
一种可能的设计中，通信模块，具体用于向第一终端设备发送第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，通信模块，具体用于向第一终端设备发送用于配置第一终端设备激活STP功能的参数。
一种可能的设计中，用于配置第一终端设备激活STP功能的参数包括以下一项或者多项：第四端口的端口号或第四端口的优先级，第四端口为第一终端设备上PDU会话对应的端口。
一种可能的设计中，通信模块，具体用于获取第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能；当第一STP能力信息用于指示第一终端设备支持STP功能时，向第一终端设备发送第二指示信息。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息。
一种可能的设计中，通信模块，还用于从移动管理网元获取第一STP能力信息。
一种可能的设计中，通信模块，还用于在第一用户面网元不为第一终端设备所属群组中的任意一个终端设备提供服务的情况下，向第一用户面网元发送第三指示信息，第三指示信息用于指示去激活STP功能。
第十一方面，提供一种通信装置，包括处理模块和通信模块。其中，通信模块，用于接收会话管理网元发送的第一指示信息，第一指示信息用于指示激活STP功能。处理模块，具体用于根据第一指示信息，激活STP功能。
一种可能的设计中，第一指示信息用于指示激活STP功能，包括：第一指示信息用于指示针对第一终端设备所属群组激活STP功能。
一种可能的设计中，第一指示信息包括第一终端设备所属群组的标识。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第一指示信息承载于N4接口消息中。
一种可能的设计中，通信模块，还用于接收会话管理网元发送的用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，用于配置第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥媒体接入控制MAC地址、第一端口的优先级、第一端口的端口号、第二端口的端口号、第二端口的优先级、第三端口的端口号、或第三端口的优先级；其中，第一端口为第一用户面网元上PDU会话对应的端口，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，通信模块，还用于接收会话管理网元发送的第三指示信息，第三指示信息用于指示去激活STP功能；第一用户面网元根据第三指示信息，去激活STP功能。
第十二方面，提供一种通信装置，包括：通信模块和处理模块。其中，通信模块，用于
向会话管理网元发送PDU会话建立请求消息。处理模块，用于接收会话管理网元发送的第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，通信模块，还用于接收会话管理网元发送的用于配置第一终端设备激活STP功能时使用的参数。
一种可能的设计中，用于配置第一终端设备激活STP功能时使用的参数包括以下参数中的一项或者多项：第四端口的端口号、或第四端口的优先级，第四端口为第一终端设备上PDU会话对应的端口。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP。
一种可能的设计中，通信模块，还用于在注册流程中发送第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能。
第十三方面，提供一种通信装置，包括通信模块和处理模块。通信模块，用于接收来自第一终端设备的PDU会话建立请求消息。处理模块，用于根据PDU会话建立请求消息，选择第一用户面网元。通信模块，还用于向第一终端设备发送第一消息，第一消息用于确定局域网桥LAN Bridge的桥标识，LAN Bridge包括第一用户面网元以及第一终端设备。
一种可能的设计中，第一消息包括LAN bridge的桥优先级和/或桥MAC地址。或者，第一消息包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一消息包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，通信模块，还用于向第一用户面网元发送第二消息，第二消息用于确定LAN Bridge的桥标识。
一种可能的设计中，第二消息还包括LAN bridge的桥优先级和/或桥MAC地址。或者，第二消息包括LAN bridge的桥标识。
一种可能的设计中，第二消息还包括第一指示信息，第一指示信息用于指示激活STP功能。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第二消息还包括第一终端设备所属群组的标识。
一种可能的设计中，通信模块，还用于向第一用户面网元发送用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，参数包括以下一项或者多项：第二端口的端口号、第二端口的优先级、第二端口的QoS参数、第三端口的端口号或第三端口的优先级，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，通信模块，具体用于根据第一终端设备所属群组的标识，获取与第一终端设备所属群组关联的运营商策略信息；当运营商策略信息用于指示激活STP功能时，向第一终端设备发送第一消息。
一种可能的设计中，通信模块，具体用于根据第一终端设备所属群组的标识，获取与第一终端设备所属群组的签约信息；在签约信息包括用于指示激活STP功能的指示信息的情况下，向第一终端设备发送第一消息。
一种可能的设计中，通信模块，具体用于从策略控制功能网元获取第一终端设备的策略与计费控制规则；在策略与计费控制规则包括用于指示激活STP功能的指示信息的情况下，向第一终端设备发送第一消息。
一种可能的设计中，通信模块，具体用于从本地获取第一终端设备所属群组相关的5GLAN的用户面拓扑；在5GLAN的用户面拓扑存在多个用于与数据网络连接的端口，或者5GLAN的用户面拓扑中存在多个用户面网元的情况下，向第一终端设备发送第一消息。
一种可能的设计中，通信模块，具体用于获取第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能；当第一STP能力信息用于指示第一终端设备支持STP功能时，向第一终端设备发送第一消息。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息。
一种可能的设计中，通信模块，还用于从移动管理网元获取第一STP能力信息。
第十四方面，提供一种通信装置，应用于第一用户面网元。该通信装置包括处理模块和通信模块。通信模块，用于接收第二消息，第二消息用于确定第一用户面网元所在的LAN Bridge的桥标识，LAN Bridge包括第一用户面网元以及连接到第一用户面网元的第一终端设备。处理模块，用于根据第二消息，激活STP功能。
一种可能的设计中，第二消息包括LAN bridge的桥优先级和/或桥MAC地址。或者，第二消息包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第二消息还包括第一指示信息，第一指示信息用于指示激活STP功能。
一种可能的设计中，第一指示信息还用于指示STP版本。
一种可能的设计中，第二消息还包括第一终端设备所属群组的标识。
一种可能的设计中，通信模块，具体用于接收会话管理网元发送的用于配置第一用户面网元激活STP功能的参数。
一种可能的设计中，参数包括以下一项或者多项：第二端口的端口号、第二端口的优先级、第二端口的QoS参数、第三端口的端口号或第三端口的优先级，第二端口为第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为第一用户面网元上用于与数据网络连接的接口。
一种可能的设计中，通信模块，还用于根据LAN Bridge的桥标识，通过第一用户面网元的端口发送第四配置BPDU报文，第四配置BPDU报文中根桥标识字段的取值设置为LAN Bridge的桥标识。
一种可能的设计中，通信模块，还用于通过第一用户面网元的端口接收第三配置BPDU报文；通过第一终端设备和第一用户面网元之间的PDU会话，向第一终端设备发送第三配置BPDU报文。
一种可能的设计中，通信模块，还用于通过PDU会话，接收第一终端设备发送的第二配置BPDU报文，第二配置BPDU报文是第一终端设备的端口接收到的配置BPDU报文。
一种可能的设计中，处理模块，还用于根据第四配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN Bridge的桥角色，桥角色为根桥或者非根桥。
第十五方面，提供一种通信装置，应用于第一终端设备。该通信装置包括：通信模块和处理模块。其中，通信模块，用于向会话管理网元发送PDU会话建立请求消息，PDU会话建立请求消息用于请求建立PDU会话；接收会话管理网元发送的第一消息，第一消息用于确定LAN Bridge的桥标识，LAN Bridge包括第一终端设备以及第一终端设备连接到的第一用户面网元。处理模块，用于根据第一消息，激活STP功能。
一种可能的设计中，第一消息可以包括LAN bridge的桥优先级和/或桥MAC地址。或者，第一消息包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一消息还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，通信模块，还用于通过第一终端设备的端口发送第一配置BPDU报文，第一配置BPDU报文中根桥标识字段的取值设置为LAN Bridge的桥标识。
一种可能的设计中，通信模块，还用于通过第一终端设备的端口接收第二配置BPDU报文；通过PDU会话，向第一用户面网元发送第二配置BPDU报文。
一种可能的设计中，处理模块，还用于当第二配置BPDU报文的根桥标识字段的取值为LAN Bridge的桥标识时，将接收到第二配置BPDU报文的端口设置为阻塞状态。
一种可能的设计中，通信模块，还用于通过PDU会话，接收第一用户面网元发送的第三配置BPDU报文，第三配置BPDU报文是第一用户面网元的端口接收到的配置BPDU报文。
一种可能的设计中，处理模块，还用于根据第一配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN bridge的桥角色，桥角色为根桥或者非根桥。
一种可能的设计中，PDU会话建立请求消息包括第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP。
一种可能的设计中，通信模块，还用于在注册流程中向移动管理网元发送第一STP能力信息，第一STP能力信息用于指示第一终端设备是否支持STP功能。
第十六方面，提供一种通信装置，包括：处理模块和通信模块。通信模块，用于接收第三消息，第三消息包括第一容器，第一容器包括第一终端设备相关的STP信息。处理模块，用于根据第三消息，生成第三容器。通信模块，还用于向第一终端设备发送第三容器，第三容器用于确定LAN bridge的桥标识，LAN Bridge包括第一终端设备和第一终端设备连接到的第一用户面网元。
一种可能的设计中，第三容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第三容器包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一终端设备相关的STP信息包括第一STP能力信息和/或第一STP版本信息，第一STP能力信息用于指示第一终端设备是否支持STP功能，第一STP版本信息用于指示第一终端设备支持的STP版本。
一种可能的设计中，第三容器还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第三消息还包括第一终端设备所属群组的标识。
一种可能的设计中，第三消息还包括第二容器，第二容器包括第一用户面网元相关的STP信息。
一种可能的设计中，第一用户面网元相关的STP信息包括第二STP能力信息和/或第二STP版本信息，第二STP能力信息用于指示第一用户面网元是否支持STP功能，第二STP版本信息用于指示第一用户面网元支持的STP版本。
一种可能的设计中，通信模块，还用于向第一用户面网元发送第四容器，第四容器用于确定LAN Bridge的桥标识。
一种可能的设计中，第四容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第四容器包括LAN bridge的桥标识。
一种可能的设计中，第四容器还包括第一指示信息，第一指示信息用于指示激活 STP功能。
第十七方面，提供一种通信装置，应用于第一终端设备。该通信装置包括：处理模块和通信模块。其中，通信模块，用于向应用功能网元发送第一容器，第一容器包括第一终端设备相关的STP信息；接收应用功能网元发送的第三容器，第三容器用于确定LAN bridge的桥标识，LAN Bridge包括第一终端设备和第一终端设备连接到的第一用户面网元。处理模块，用于根据第三容器，激活STP功能。
一种可能的设计中，第三容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第三容器包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第一终端设备相关的STP信息包括第一STP能力信息和/或第一STP版本信息，第一STP能力信息用于指示第一终端设备是否支持STP功能，第一STP版本信息用于指示第一终端设备支持的STP版本。
一种可能的设计中，第三容器还包括第二指示信息，第二指示信息用于指示第一终端设备激活STP功能。
一种可能的设计中，第二指示信息还用于指示STP版本。
一种可能的设计中，通信模块，还用于通过第一终端设备的端口发送第一配置BPDU报文，第一配置BPDU报文中根桥标识字段的取值设置为LAN Bridge的桥标识。
一种可能的设计中，通信模块，还用于通过第一终端设备的端口接收第二配置BPDU报文；通过PDU会话，向第一用户面网元发送第二配置BPDU报文。
一种可能的设计中，处理模块，用于当第二配置BPDU报文的根桥标识字段的取值为LAN Bridge的桥标识时，将接收到第二配置BPDU报文的端口设置为阻塞状态。
一种可能的设计中，通信模块，还用于通过PDU会话，接收第一用户面网元发送的第三配置BPDU报文，第三配置BPDU报文是第一用户面网元的端口接收到的配置BPDU报文。
一种可能的设计中，处理模块，还用于根据第一配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN Bridge的桥角色，桥角色为根桥或者非根桥。
第十八方面，提供一种通信装置，应用于第一用户面网元。通信装置包括：处理模块和通信模块。通信模块，还用于接收应用功能网元发送的第四容器，第四容器用于确定LAN Bridge的桥标识，LAN Bridge包括第一用户面网元与连接到第一用户面网元的第一终端设备。处理模块，还用于根据第四容器，激活STP功能。
一种可能的设计中，第四容器包括LAN bridge的桥优先级和/或桥MAC地址。或者，第四容器包括LAN bridge的桥标识。
一种可能的设计中，LAN Bridge还包括连接到第一用户面网元的第二终端设备。
一种可能的设计中，第二终端设备与第一终端设备属于同一个群组。
一种可能的设计中，第四容器还包括第一指示信息，第一指示信息用于指示第一用户面网元激活STP功能。
一种可能的设计中，通信模块，还用于向会话管理网元发送第二容器，第二容器包括第一用户面网元相关的STP信息。
一种可能的设计中，第一用户面网元相关的STP信息包括第二STP能力信息和/或第二STP版本信息，第二STP能力信息用于指示第一用户面网元是否支持STP功能，第二STP版本信息用于指示第一用户面网元支持的STP版本。
一种可能的设计中，通信模块，还用于根据LAN Bridge的桥标识，通过第一用户面网元的端口发送第四配置BPDU报文，第四配置BPDU报文中根桥标识字段的取值设置为LAN Bridge的桥标识。
一种可能的设计中，通信模块，还用于通过第一用户面网元的端口接收第三配置BPDU报文；通过第一终端设备和第一用户面网元之间的PDU会话，向第一终端设备发送第三配置BPDU报文。
一种可能的设计中，通信模块，还用于通过PDU会话，接收第一终端设备发送的第二配置BPDU报文，第二配置BPDU报文是第一终端设备的端口接收到的配置BPDU报文。
一种可能的设计中，处理模块，还用于根据第四配置BPDU报文、第二配置BPDU报文和第三配置BPDU报文，确定LAN Bridge的桥角色，桥角色为根桥或者非根桥。
第十九方面，提供一种通信装置，包括处理器和通信接口，处理器用于执行计算机程序指令，使得通信装置实现第一方面至第九方面中任一方面所提供的任一种设计所涉及的避免环路的方法。
第二十方面，提供一种计算机可读存储介质，计算机可读存储介质存储有指令，当指令在计算机上运行时，使得计算机实现第一方面至第九方面中任一方面所提供的任一种设计所涉及的避免环路的方法。
第二十一方面，提供一种包含计算机指令的计算机程序产品，当计算机程序产品在计算机上运行时，使得计算机实现第一方面至第九方面中任一方面所提供的任一种设计所涉及的避免环路的方法。
第二十二方面，提供一种芯片，该芯片包括处理器和收发器，当处理器执行计算机程序指令时，实现第一方面至第九方面中任一方面所提供的任一种设计所涉及的避免环路的方法。
其中，第十方面至第二十二方面中任一种设计方式所带来的技术效果可参见上文所提供的对应的方法中的有益效果，此处不再赘述。
附图说明
图1为5GLAN与存量LAN互通场景的示意图；
图2为5GLAN的系统架构的示意图；
图3为本申请实施例提供的一种5G网络的架构示意图；
图4(a)为本申请实施例提供的一种5GLAN与存量LAN互通场景的示意图；
图4(b)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图4(c)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图4(d)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图4(e)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图5为本申请实施例提供的一种避免环路的方法的流程图；
图6为本申请实施例提供的另一种避免环路的方法的流程图；
图7(a)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图7(b)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图8(a)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图8(b)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图9为本申请实施例提供的一种避免环路的方法的流程图；
图10为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图11为本申请实施例提供的另一种避免环路的方法的流程图；
图12为本申请实施例提供的另一种避免环路的方法的流程图；
图13为本申请实施例提供的另一种避免环路的方法的流程图；
图14为本申请实施例提供的另一种避免环路的方法的流程图；
图15为本申请实施例提供的另一种避免环路的方法的流程图；
图16(a)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图16(b)为本申请实施例提供的另一种5GLAN与存量LAN互通场景的示意图；
图17为本申请实施例提供的一种STP功能的管理方法的流程图；
图18为本申请实施例提供的一种通信装置的结构示意图；
图19为本申请实施例提供的另一种通信装置的结构示意图。
具体实施方式
在本申请的描述中，除非另有说明，“/”表示“或”的意思，例如，A/B可以表示A或B。本文中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。此外，“至少一个”是指一个或多个，“多个”是指两个或两个以上。“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。
需要说明的是，本申请中，“示例性的”或者“例如”等词用于表示作例子、例证或说明。本申请中被描述为“示例性的”或者“例如”的任何实施例或设计方案不应被解释为比其他实施例或设计方案更优选或更具优势。确切而言，使用“示例性的”或者“例如”等词旨在以具体方式呈现相关概念。
为了便于理解本申请的技术方案，下面先对本申请所涉及的技术术语进行简单介绍。
1、PDU会话
5G核心网支持PDU连接业务，PDU连接业务就是终端设备和数据网络(data network，DN)之间交换PDU数据包的业务。PDU连接业务通过终端设备发起PDU会话的建立来实现。终端设备建立PDU会话，也就是建立了一条终端设备和DN之间的数据传输通道。
需要说明的是，终端设备可以发起建立一个或多个PDU会话，来连接到相同的DN或者不同的DN。终端设备可以由一组核心网网元(如会话管理功能(session management function，SMF)网元、策略控制功能(policy control function，PCF)网元和用户面功能(user plane function，UPF)网元等)服务，这些核心网网元协调着管理终端设备的PDU会话资源。
2、N4会话
N4会话是由SMF在UPF上创建的，目的在于管理为PDU会话提供服务的UPF的功能。例如，在终端设备建立PDU会话时，SMF可以指示UPF创建与PDU会话对应的N4会话。当SMF接收到删除PDU会话请求时，SMF会触发UPF删除与该PDU会话对应的N4会话。在一些情况下，SMF还可以触发UPF修改与PDU会话对应的N4会话。
在本申请实施例中，N4会话可以分为用户级别(或者说终端设备级别)的N4会话以及群组级别的N4会话。
在创建N4会话的过程中，SMF和UPF均会生成N4会话上下文，以存储与N4会话相关的参数。N4会话上下文可以包括：N4会话ID，用于该N4会话的N4路由规则，包括：分组检测规则(packet detection rule，PDR)，转发动作规则(forwarding action rule，FAR)，服务质量(quality of services，QoS)执行规则(QoS enforcement rule，QER)和统计信息上报规则(usage reporting rule，URR)。
UPF通过使用N4会话上下文中的PDR、FAR、QER、URR等参数，来实现对PDU会话的报文的检测、转发。
示例性的，UPF在从入口接收到报文后，UPF使用PDR确定该报文所属的N4会话。然后，UPF使用该N4会话上下文中的PDR(可能是一个或多个)与报文的特性信息进行匹配，找到与报文相匹配的PDR。该PDR关联或指定报文对应的FAR、QER和URR。从而，UPF可以根据FAR对报文执行丢弃(drop)、转发(forward)、缓存(buffer)、上报控制面(notify)或者复制(duplicate)操作等。UPF可以根据QER对报文执行QoS操作。UPF可以根据URR对报文执行统计信息上报。
3、生成树协议(spanning tree protocol，STP)
STP工作在数据链路层，用于生成以太网中无环路的逻辑拓扑结构，可以防止交换机冗余链路产生的环路，其原理为：任意一个交换机中如果到达根网桥有两条或者两条以上的链路，通过一定的算法实现路径冗余，同时将环路网络修剪成无环路的树型网络，从而保证任意两个交换机之间只有一条单一的活动链路，避免报文在环路网络中的增生和无限循环。
树形的网络结构中需要存在一个根节点。在STP中，该根节点被称为根桥。根桥是整个网络的逻辑中心，但不一定是网络的物理中心。网络中除了根桥之外的其他设备可以被称为非根桥。应理解，在网络拓扑发生变化的情况下，根桥也可能改变。
STP算法的两大基本度量依据是标识(identity，ID)和路径开销(path cost)。
ID分为桥标识(bridge identity，BID)和端口标识(port identity，PID)。
BID由桥优先级(bridge priority)和桥MAC地址构成。以BID占用8个字节为例，BID所占用的8个字节中的前2个字节用于承载桥优先级，后6个字节用于承载桥MAC地址。在STP网络中，BID最小的设备会被选举为根桥。
PID由端口优先级(port priority)和端口号构成。PID用于在一些情况下作为设备上选择指定端口的依据。
路径开销是一个端口变量，是STP用于选择链路的参考值。STP通过计算路径开销，选择较为“强壮”的链路，阻塞多余的链路，将网络修剪成无环路的树形网络拓 扑结构。在一个STP网络中，端口的根路径开销(root path cost，RPC)即为该端口到根桥的路径中所经过的各个桥的端口的路径开销累加而成。
STP将环形网络拓扑结构变为树形网络拓扑结构，主要考虑以下三个要素：根桥、根端口(root port，RP)和指定端口(designated port，DP)。
根桥是网络中BID最小的设备。
根端口是指设备上去往根桥路径最近的端口。端口负责向根桥方向转发数据。在一个运行STP的设备上，根端口有且只有一个。应理解，根桥上没有根端口。根端口的主要选择标准是依据根路径开销(root path cost，RPC)判定。在一台设备上所有使能STP的端口中，根路径开销最小者，就是根端口。
对一台交换设备而言，它的指定端口是向下游交换设备转发BPDU报文的端口。根桥的所有端口都是指定端口。在环网的每一网段都会选举出一个指定端口，在一个网段上拥有指定端口的交换设备被称作该网段的指定桥。
可选的，STP中还存在一种端口角色：替代端口(alternate port，AP)。替代端口为设备提供一条到根桥的替代路径。从而，在根端口发生故障等情况下，设备可以使用替代端口与根桥进行通信。
示例性的，如表1所示，STP包含以下端口状态。
表1
Figure PCTCN2021142184-appb-000001
目前，网络中各个设备通过交互BPDU报文，以选举的方式确定根桥、根端口和指定端口。BPDU报文主要包括以下字段：根桥标识(root identity，RID)字段、根路径开销字段、桥标识(bridge identity，BID)字段以及端口标识字段。其中，对于一个BPDU报文来说，根桥标识字段设置为发送该BPDU报文的交换机所认为的根桥的BID；根路径开销字段设置为发送该BPDU报文的交换机的端口到达根桥的最短路径开销。桥标识字段设置为发送该BPDU报文的交换机的BID。端口标识字段设置为发送该BPDU报文的交换机的端口的PID。
应理解，上述BPDU报文一般会按照规定的时间间隔进行发送。
STP主要包括选举过程和维护过程。
(1)选举过程包括以下步骤：
S1、在以太局域网初始化时，所有的交换机均认为自己是根桥，并发送BPDU报文。应理解，在设备的每个端口所发出的BPDU报文中，根桥标识字段设置为设备自身的BID，桥标识字段设置为设备自身的BID，端口标识字段设置为发送该BPDU报文的端口的PID。
S2、网络中的设备通过交换BPDU报文，比较各个设备的BID，选择BID最小的设备作为根桥。
S3、在根桥选举完成之后，根桥将以默认2秒的通告周期，发送以自己为根桥的BPDU报文，其他交换机根据收到的BPDU报文选择一个根端口，并且将BPDU报文中的BID替换为自身的BID，再从自己的指定端口转发给连接的其他交换机。设备上没有成为指定端口以及根端口的其他端口将被阻塞(blocking)。
(2)维护过程包括以下步骤：
在网络完成选举过程之后，为了保持网络的稳定性，根桥继续周期性发送BPDU报文，设备上被阻塞的端口会不断的侦听对端发送的BPDU。如果超过一定时间内没有收到BPDU报文，设备上的阻塞状态认为网络发生变化，从而触发网络重新进行收敛计算。
以上是对本申请实施例所涉及的术语的介绍，以下不再赘述。
针对5GLAN服务，第三代合作伙伴计划(3rd generation partnership project，3GPP)提出要支持5GLAN的一对一和一对多通信。具体的，要支持5GLAN的一对一和一对多通信，要求3GPP网络支持基于群组的单播、组播和广播，支持对组播和广播报文进行复制分发，以及支持任意终端设备作为组播源。
为满足该需求，当前3GPP技术标准(technical specification，TS)23.501定义一个5GLAN由一个SMF管理。如图2所示，该SMF同时管理一个或者多个UPF。图2中以SMF管理UPF1和UPF2为例进行绘制，UPF1和UPF2上维护有路由规则，UPF1和UPF2可以根据自身维护的路由规则进行报文的转发。假设终端设备1、终端设备2以及终端设备3属于同一个群组。当由相同的UPF服务的两个终端设备(例如，图2中的终端设备1和终端设备2)之间一对一通信时，通过UPF本地交换(local switch)方式传输数据。当不同的UPF服务的两个终端设备(例如，图2中的终端设备1和终端设备3)之间一对一通信，则需通过UPF1和UPF2之间的隧道传输数据。
在本申请实施例中，两个UPF之间可以通过SMF交互隧道信息，来建立隧道。UPF之间的隧道(或转发路径)可以采用虚拟本地局域网(virtual LAN，VLAN)，虚拟扩展局域网(virtual extensible LAN，VxLAN)，通用分组无线业务(general packet radio service，GPRS)隧道协议用户面(GPRS tunneling protocol-user plane，GTP-U)，通用路由封装协议(generic routing encapsulation，GRE)或者IP隧道方式来构建。上述构建方式可以是动态的，也可以在网络中预配置好的，本申请实施例对此不作具体限定。
其中，采用不同的构建方式，对应的隧道信息并不相同。例如采用VLAN方式构建时，隧道信息可以是UPF ID、UPF ID+虚拟本地局域网标识(VLAN ID，VID)或 者媒体接入控制(media access control，MAC)+VID；或者，例如采用VxLAN方式构建时，隧道信息可以是UPF ID、UPF ID+VID、IP地址+VID、或者IP地址+端口号(port)+VID；或者，例如采用GTP-U方式构建时，隧道信息可以是UPF ID、UPF ID+隧道端点标识(tunnel endpoint identifier，TEID)、IP地址+TEID、或者IP地址+port+TEID；或者，例如采用GRE方式构建时，隧道信息可以是UPF ID、UPF ID+密钥(key)、IP地址+key、或者IP地址+port+key；或者，采用IP隧道方式构建时，隧道信息可以是UPF ID、IP地址、或者IP地址+port。其中，若隧道信息中有UPF ID，UPF ID可以是MAC地址或者IP地址，或者IP地址+port，或者SMF网元或者UPF网元可以根据UPF ID确定对应的MAC地址或者IP地址，或者IP地址+port，在此统一说明，以下不再赘述。
本申请实施例中，一个5GLAN可以为一个群组提供群组通信服务，即一个5GLAN可以对应一个群组。一个SMF或者UPF也可以为多个群组提供通信服务。
可选的，从表达方式上看，5GLAN还可以称为5G虚拟网络(5G virtual network，5G VN)，5G VN group，5G LAN-VN group，LAN-类型服务(type service)，LAN-VN，或者5G LAN-type service(类型服务)等，本申请实施例对5GLAN的名称不作具体限定。
在图2所示的架构中，SMF主要负责终端设备会话管理的所有控制面功能，包括UPF的选择与控制，IP地址分配及管理，会话的服务质量(quality of service，QoS)管理，从PCF获取策略与计费控制(policy and charging control，PCC)规则等。
在图2所示的架构中，UPF作为PDU会话连接的锚定点，负责对终端设备的数据报文过滤、数据传输/转发、速率控制、生成计费信息、用户面QoS处理、上行传输认证、传输等级验证、下行数据包缓存及下行数据通知触发等。
在图2所示的架构中，无线接入网(radio access network，RAN)是指RAN节点，RAN节点也可以称为接入网设备。例如，可以为传输接收点(transmission reception point，TRP)、基站、各种形式的控制节点(例如，网络控制器、无线控制器(例如，云无线接入网络(cloud radio access network，CRAN)场景下的无线控制器))等。具体的，RAN节点可以为各种形式的宏基站，微基站(也称为小站)，中继站，接入点(access point，AP)等，也可以为基站的天线面板。所述控制节点可以连接多个基站，并为所述多个基站覆盖下的多个终端设备配置资源。在采用不同的无线接入技术的系统中，具备基站功能的设备的名称可能会有所不同。例如，长期演进(long term evolution，LTE)系统中可以称为演进型基站(evolved NodeB，eNB或eNodeB)，5G系统或NR系统中可以称为下一代基站节点(next generation node base station，gNB)，本申请对基站的具体名称不作限定。RAN节点还可以是未来演进的公共陆地移动网络(public land mobile network，PLMN)中的网络设备等。
在图2所示的架构中，终端设备是用户侧的一种用于接收信号和/或发送信号的实体。终端设备用于向用户提供语音服务和数据连通性服务中的一种或多种。终端设备还可以称为用户设备(user equipment，UE)、终端、接入终端设备、用户单元、用户站、移动站、远方站、远程终端设备、移动设备、用户终端设备、无线通信设备、用户代理或用户装置。终端设备可以是车联万物(vehicle to everything，V2X)设备，例 如，智能汽车(smart car或intelligent car)、数字汽车(digital car)、无人汽车(unmanned car或driverless car或pilotless car或automobile)、自动汽车(self-driving car或autonomous car)、纯电动汽车(pure EV或Battery EV)、混合动力汽车(hybrid electric vehicle，HEV)、增程式电动汽车(range extended EV，REEV)、插电式混合动力汽车(plug-in HEV，PHEV)、新能源汽车(new energy vehicle)、路边装置(road site unit，RSU)。终端设备也可以是设备到设备(device to device，D2D)设备，例如，电表、水表等。终端设备还可以是移动站(mobile station，MS)、用户单元(subscriber unit)、无人机、物联网(internet of things，IoT)设备、WLAN中的站点(station，ST)、蜂窝电话(cellular phone)、智能电话(smart phone)、无绳电话、无线数据卡、平板型电脑、会话启动协议(session initiation protocol，SIP)电话、无线本地环路(wireless local loop，WLL)站、个人数字处理(personal digital assistant，PDA)设备、膝上型电脑(laptop computer)、机器类型通信(machine type communication，MTC)终端设备、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备(也可以称为穿戴式智能设备)。终端设备还可以为下一代通信系统中的终端设备，例如，5G系统中的终端设备或者未来演进的PLMN，NPN中的终端设备等。
可选的，如图3所示，目前的5G网络还可以包括以下网元：接入和移动性管理功能(core access and mobility management function，AMF)网元、认证服务器功能(authentication server function，AUSF)网元、网络切片选择功能(network slice selection function，NSSF)网元、网络开放功能(network exposure function，NEF)网元、网络功能存储功能(network exposure function Repository Function，NRF)网元、策略控制功能(policy control function，PCF)网元、统一数据管理(unified data management，UDM)网元以及应用功能(application function，AF)网元等，本申请实施例对此不作具体限定。
其中，终端设备通过下一代网络(Next generation，N)1接口(简称N1)与AMF网元通信，RAN设备通过N2接口(简称N2)与AMF网元通信，RAN设备通过N3接口(简称N3)与UPF网元通信，UPF网元通过N6接口(简称N6)与DN通信。
AMF网元、SMF网元、UDM网元、AUSF网元、或者PCF网元等控制面网元也可以采用服务化接口进行交互。比如，如图3所示，AMF对外提供的服务化接口可以为Namf；SMF网元对外提供的服务化接口可以为Nsmf；UDM网元对外提供的服务化接口可以为Nudm；PCF网元对外提供的服务化接口可以为Npcf，AUSF网元对外提供的服务化接口可以为Nausf；在此不再一一描述。上述服务化接口的名称仅是示例，不作具体限定。
目前，终端设备通过建立PDU会话访问5GLAN服务，可以使得5GLAN与存量LAN互通。例如，如图4(a)所示，UE1与UE2构成一个本地LAN。在UE1发起PDU会话建立流程之后，UE1与UPF1之间建立PDU会话。这样一来，5GLAN中的UPF1可以连通UE1和UE2构成的LAN，以及UE3、UE4以及UE5构成的LAN。
应理解，存量LAN是指与5GLAN区别的LAN。例如，存量LAN可以是终端设备建立PDU会话访问5GLAN服务之前已连接的LAN。可选的，存量LAN可以有其 他名称，例如外部LAN、LAN等，对此不作限定。
但是，一些情况下，5GLAN与存量LAN互通，可能造成环路的出现。下面以举例的方式对几种可能的情况进行说明。
以图4(b)为例，UE1与UPF1之间已经建立PDU会话，UE1还与UE2连接。这种情况下，在UE2发起PDU会话建立流程之后，UE2与UPF1之间建立PDU会话。从而，UE2、UE1与UPF之间的通信链路构成环路。
以图4(c)为例，UE1与DN1之间存在通信链路，UPF1与DN1之间存在通信链路。这种情况下，在UE1发起PDU会话建立流程之后，UE1与UPF1之间建立PDU会话。从而，UE1、UPF1与DN1之间的通信链路构成环路。
以图4(d)为例，UE1与UPF1之间已经建立PDU会话，UE1还与UE2连接。在UE2发起PDU会话建立流程之后，UE2与UPF2之间建立PDU会话，UPF2与UPF1之间建立N19隧道。从而，UE1、UE2、UPF1与UPF2之间的通信链路构成环路。
以图4(e)为例，UE1与UPF1之间已经建立PDU会话，UE1还与UE2连接，UPF1还与DN1连接。在UE2发起PDU会话建立流程之后，UE2与UPF2之间建立PDU会话，UPF2与UPF1之间建立N19隧道，UPF2与DN1连接。从而，UE1、UE2、DN1、UPF1与UPF2之间的通信链路构成环路。
当网络中存在环路时，会导致广播报文出现增生和无限循环的现象，影响网络的正常通信。因此，在5GLAN和存量LAN互通的场景下，如何避免环路，是亟待解决的技术问题。
下面将结合说明书附图，对用于解决上述技术问题的技术方案进行具体介绍。
实施例一
如图5所示，为本申请实施例提供的一种避免环路的方法，该方法包括以下步骤：
S101、第一终端设备向会话管理网元发送PDU会话建立请求消息。相应的，会话管理网元接收第一终端设备发送的PDU会话建立请求消息。
其中，PDU会话建立请求消息用于请求建立PDU会话。PDU会话建立请求消息包括：第一终端设备所属群组的标识。
在本申请实施例中，群组的标识用于确定对应的5GLAN群组。群组的标识例如可以为：数据网络名称(data network name，DNN)、组标识(Group ID)、DNN+单网络切片选择辅助信息(single network slice selection assistance information，S-NSSAI)标识等。
可选的，步骤S101可以具体实现为：第一终端设备向移动管理网元发送PDU会话建立请求消息。移动管理网元选择为第一终端设备提供服务的会话管理网元。之后，移动管理网元向会话管理网元发送PDU会话建立请求消息。
可选的，第一终端设备所发送的PDU会话建立请求消息可以包括第一STP能力信息和/或第一STP版本信息。其中，第一STP能力信息用于指示第一终端设备是否支持STP功能。第一STP版本信息用于指示第一终端设备支持的STP版本。
可选的，第一终端设备可以在注册流程中向移动管理网元发送第一STP能力信息和/或第一STP版本信息。进而，移动管理网元保存有第一STP能力信息和/或第一STP版本信息。之后，在移动管理网元接收到PDU会话建立请求消息之后，移动管理网元 可以将PDU会话建立请求消息以及第一STP能力信息和/或第一STP版本信息封装为N11消息，并将N11消息发送给会话管理网元。
S102、会话管理网元根据PDU会话建立请求消息，选择第一用户面网元。
其中，第一用户面网元用于为第一终端设备提供5GLAN服务。
作为一种可能的实现方式，会话管理网元可以根据第一终端设备的位置、第一终端设备所属群组的标识、会话管理网元所管理的各个用户面网元的服务范围、会话管理网元所管理的各个用户面网元的服务能力等因素，选择第一用户面网元。
S103、会话管理网元向第一用户面网元发送第一指示信息。相应的，第一用户面网元接收会话管理网元发送的第一指示信息。
其中，第一指示信息用于指示激活STP功能。
例如，第一指示信息用于指示第一用户面网元激活STP功能。
又例如，第一指示信息用于指示第一用户面网元针对第一终端设备所属群组激活STP功能。可选的，这种情况下，第一指示信息可以包括第一终端设备所属群组的标识。
可选的，第一指示信息还可以用于指示STP版本。示例性的，STP版本可以包括但不限于：快速生成树协议(rapid spanning tree protocol，RSTP)和/或多生成树协议(multiple spanning tree protocol，MSTP)。
应理解，在第一指示信息还用于指示一个或多个STP版本的情况下，第一用户面网元从第一指示信息所指示的STP版本中，选择激活STP功能时使用的一个STP版本。或者，在第一指示信息未指示STP版本的情况下，第一用户面网元从自身支持的一个或多个STP版本，选择激活STP功能时使用的一个STP版本。
在本申请实施例中，第一指示信息可以承载于N4接口消息中。示例性的，第一指示信息可以承载于新增的一条N4接口消息中。或者，第一指示信息可以承载于现有的N4接口消息，例如PDU会话对应的N4会话创建/修改消息。
可选的，步骤S103可以具体实现为：在满足第一预设条件的情况下，会话管理网元向第一用户面网元发送第一指示信息。
示例性的，第一预设条件可以包括以下一项或者多项：
条件1-1、会话管理网元获取到的运营商策略信息用于指示允许激活STP功能。
也就是说，运营商策略信息可以用于控制会话管理网元是否发送第一指示信息，进而间接控制是否触发第一用户面网元激活STP功能，以实现对运营商网络的更好管理，满足不同场景下的不同需求。
在本申请实施例中，会话管理网元可以从操作维护管理(operation administration and maintenance，OAM)系统获取运营商策略信息。可选的，该运营商策略信息可以应用于整个运营商网络，或者该运营商策略信息应用于第一终端设备所属的群组。
可选的，在运营商策略信息用于指示允许激活STP功能时，运营商策略信息还可以用于指示以下内容中的一部分或者全部：
(1)运营商策略信息还可以用于指示是否以用户面网元作为根桥。
应理解，当运营商策略信息用于指示以用户面网元作为根桥时，会话管理网元应将第一用户面网元的BID配置得较小，以便于网络中的其他设备选举第一用户面网元 作为根桥。
(2)运营商策略信息还可以用于指示是否保留PDU会话。
应理解，当运营商策略信息用于指示保留PDU会话时，会话管理网元应将第一用户面网元上第一端口的PID配置得较小，以便于在STP选举过程中第一端口被确定为根端口或者指定端口。其中，第一端口为第一用户面网元和第一终端设备之间的PDU会话在第一用户面网元上对应的端口。
(3)运营商策略信息还可以用于指示是否保留N19隧道。
应理解，当运营商策略信息用于指示保留N19隧道时，会话管理网元应将第一用户面网元上第二端口的PID配置得较小，以便于在STP选举过程中第二端口被确定为根端口或者指定端口。其中，第二端口为第一用户面网元与第二用户面网元之间的隧道在第一用户面网元上对应的端口。
应理解，上述运营商策略信息所包括的内容可以影响到后续会话管理网元为第一用户面网元配置的用于激活STP功能时的参数。
条件1-2、会话管理网元获取到的第一终端设备所属群组的签约信息包括用于指示允许激活STP功能的指示信息。
也就是说，签约信息可以用于控制会话管理网元是否发送第一指示信息，进而间接控制是否触发第一用户面网元激活STP功能，以实现对第一终端设备所属群组关联的5GLAN的更好管理，满足不同场景下的不同需求。
在本申请实施例中，会话管理网元根据第一终端设备所属群组的标识，从统一数据管理网元获第一终端设备所属群组的签约信息。应理解，会话管理网元可以从第一终端设备发送的PDU会话建立请求消息中，获取到第一终端设备所属群组的标识。
一种可能的设计中，统一数据管理网元可以通过网络开放功能网元接收应用功能网元发送的第一终端设备所属群组相关的配置信息，第一终端设备所属群组相关的配置信息可以包括用于指示允许激活STP功能的指示信息。从而，统一数据管理网元可以为第一终端设备所属群组的签约信息增加用于指示允许激活STP功能的指示信息。
示例性的，第一终端设备所属群组相关的配置信息还可以包括一个或多个存量LAN信息、STP版本信息等，对此不作限定。
条件1-3、会话管理网元获取到的第一终端设备关联的策略及计费控制规则包括用于指示激活STP功能指示信息。
也就是说，策略及计费控制规则可以用于控制会话管理网元是否发送第一指示信息，进而间接控制是否触发第一用户面网元激活STP功能。
在本申请实施例中，会话管理网元可以预先和策略控制功能网元建立用于传输第一终端设备相关信息的隧道。进而，会话管理网元可以通过该隧道从策略控制功能网元获取第一终端设备关联的策略及计费控制规则。
一种可能的设计中，策略控制功能网元可以直接接收应用功能网元发送的第一终端设备所属群组相关的配置信息；或者，策略控制网元可以通过网络开放功能网元接收应用功能网元发送的第一终端设备所属群组相关的配置信息。第一终端设备所属群组相关的配置信息可以包括用于指示允许激活STP功能的指示信息。进而，策略控制功能网元可以在第一终端设备所属群组中的每个终端设备关联的策略及计费控制规则 中增加用于指示允许激活STP功能的指示信息。
条件1-4、第一终端设备所属群组关联的5GLAN用户面拓扑存在多个用于与数据网络连接的端口；和/或，第一终端设备所属群组关联的5GLAN用户面拓扑中存在多个用户面网元。
也就是说，5GLAN的用户面拓扑可以影响会话管理网元是否发送第一指示信息，进而影响第一用户面网元是否激活STP功能。从而，在5GLAN的用户面拓扑满足一定条件(例如5GLAN用户面拓扑存在多个用于与数据网络连接的端口，或者5GLAN用户面拓扑中存在多个用户面网元)，说明网络中出现环路的概率比较大，因而会话管理网元需要发送第一指示信息，以保证5GLAN与存量LAN的正常通信。
在本申请实施例中，由于会话管理网元负责管理5GLAN，因此会话管理网元可以从本地获取第一终端设备所属群组关联的5GLAN用户面拓扑。
条件1-5、第一用户面网元支持STP功能。
可选的，会话管理网元可以从本地获取第一用户面网元的第二STP能力信息。或者，会话管理网元可以从第一用户面网元获取第二STP能力信息，例如会话管理网元接收第一用户面网元发送的N4消息，该N4消息包括第二STP能力信息。其中，第二STP能力信息用于指示第一用户面网元是否支持STP功能。进而，会话管理网元可以根据第二STP能力信息，确定第一用户面网元是否支持STP功能。
可选的，会话管理网元可以从本地获取第一用户面网元的第二STP版本信息。或者，会话管理网元可以从第一用户面网元获取第二STP版本信息。其中，第二STP版本信息用于指示第一用户面网元支持的STP版本。进而，会话管理网元可以根据第二STP版本信息，从第一用户面网元支持的STP版本中选择一个目标STP版本，进而通过第一指示信息来指示第一用户面网元使用该目标STP版本。
上述第二STP版本信息和第二STP能力信息可以是集成为同一个信息，或者为不同的信息，对此不作限定。
应理解，以上条件1-1-条件1-5仅是对上述第一预设条件的示例性说明，不构成具体限定。
可选的，会话管理网元还可以向第一用户面网元发送用于配置第一用户面网元激活STP功能时使用的参数。
应理解，第一指示信息可以和用于配置第一用户面网元激活STP功能时使用的参数可以封装在同一条消息中发送给第一用户面网元。或者，第一指示信息可以和用于配置第一用户面网元激活STP功能时使用的参数还可以封装在不同消息中分别发送给第一用户面网元。
可选的，用于配置第一用户面网元激活STP功能时使用的参数可以包括以下一项或者多项：用于确定第一用户面网元的桥标识的参数，与第一用户面网元上第一端口相关的参数，与第一用户面网元上第二端口相关的参数，或者与第一用户面网元上第三端口相关的参数。
下面对用于配置第一用户面网元激活STP功能时使用的参数进行具体的介绍。
(1)用于确定第一用户面网元的桥标识的参数，例如第一用户面网元的桥优先级和/或MAC地址。
作为一种可能的实现方式，会话管理网元获取一个或多个存量LAN的配置信息。之后，会话管理网元根据一个或多个存量LAN的配置信息，确定第一用户面网元的桥优先级和/或桥MAC地址。其中，上述存量LAN可以是指与5GLAN连接的LAN。一个存量LAN的配置信息至少包括一个存量LAN的根桥的桥优先级和/或桥MAC地址。
可选的，第一用户面网元的桥优先级高于任意一个存量LAN中根桥的桥优先级。和/或，第一用户面网元的桥MAC地址小于任意一个存量LAN中根桥的桥MAC地址。这样一来，尽可能使得第一用户面网元的BID可以小于任意一个存量LAN中根桥的BID。从而，在选举过程中，第一用户面网元可以被选举为根桥，从而第一用户面网元和第一终端设备之间交互的数据，不用通过存量LAN中的其他设备进行转发，提高数据的安全性和保密性。
示例性的，会话管理网元获取存量LAN的配置信息，可以采用以下实现方式1-实现方式4中的任意一种。在此统一说明，以下不再赘述。
实现方式1、会话管理网元根据第一终端设备所属群组的标识，从统一数据管理网元获取第一终端设备所属群组关联的签约数据，该签约数据包括存量LAN的配置信息。
可选的，统一数据管理网元可以直接地从应用功能网元获取到存量LAN的配置信息。或者，统一数据管理网元可以通过网络开放功能网元从应用功能网元获取到存量LAN的配置信息。进而，统一数据管理网元在第一终端设备所属群组关联的签约数据中增加存量LAN的配置信息。
实现方式2、会话管理网元从策略控制功能网元发送的第一终端设备关联的PCC规则，该第一终端设备关联的PCC规则包括存量LAN的配置信息。
可选的，策略控制功能网元可以直接地从应用功能网元获取到存量LAN的配置信息。或者，策略控制功能网元可以通过网络开放功能网元从应用功能网元获取到存量LAN的配置信息。进而，策略控制功能网元在第一终端设备关联的PCC规则中增加存量LAN的配置信息。
实现方式3、会话管理网元从第一用户面网元获取存量LAN的配置信息。
应理解，第一用户面网元可以主动向会话管理网元上报存量LAN的配置信息。或者，第一用户面网元可以在会话管理网元的指示下，上报存量LAN的配置信息。
其中，第一用户面网元可以先获取存量LAN的配置BPDU报文。之后，第一用户面网元通过解析存量LAN的配置BPDU报文，确定存量LAN的配置信息。
实现方式4、会话管理网元从第一用户面网元获取到存量LAN的配置BPDU报文。之后，会话管理网元解析存量LAN的配置BPDU报文，确定存量LAN的配置信息。
应理解，第一用户面网元可以主动地向会话管理网元上报存量LAN的配置BPDU报文。或者，第一用户面网元可以在会话管理网元的指示下，向会话管理网元上报存量LAN的配置BPDU报文。
(2)与第一用户面网元上第一端口相关的参数，例如第一端口的端口号、第一端口的端口优先级和/或第一端口的QoS参数。其中，第一端口为第一用户面网元和第一终端设备之间的PDU会话在第一用户面网元上对应的端口。
其中，第一端口的端口优先级和端口号用于确定第一端口的端口标识。
第一端口的Qos参数用于确定第一端口的带宽。第一端口的带宽用于确定第一端口的端口开销。端口开销又可以称为本地路径开销。可选的，第一端口的QoS参数可以包括但不限于：会话(session)-聚合最大比特率(aggregate maximum bit rate，AMBR)、最大流比特速率(maximum flow bit rate，MFBR)和/或保证流比特速率(guaranteed flow bit rate，GFBR)。
上述第一端口的端口标识以及端口开销用于第一用户面网元进行STP选举或者STP维护的过程中。
作为一种可能的实现方式，会话管理网元获取一个或多个存量LAN的配置信息。之后，会话管理网元根据一个或多个存量LAN的配置信息，确定第一端口的端口号和/或优先级。其中，存量LAN的配置信息还可以包括存量LAN中各个设备上各个端口的端口号和/或优先级。
可选的，第一端口的优先级高于任意一个存量LAN中任意一个设备上端口的优先级。和/或，第一端口的端口号小于任意一个存量LAN中任意一个设备上端口的端口号。这样一来，尽可能使得第一端口的PID可以小于任意一个存量LAN中任意一个设备上端口的PID。从而，在第一用户面网元为非根桥的情况下，增大第一端口被选举为指定端口或者根端口的概率。可以理解的是，在第一端口为指定端口或者根端口的情况下，第一用户面网元和第一终端设备之间交互的数据，不用通过存量LAN中的其他设备进行转发，提高数据的安全性和保密性。
(3)与第一用户面网元上第二端口相关的参数，例如第二端口的端口号、第二端口的端口优先级和/或第二端口的QoS参数。其中，第二端口为第一用户面网元与第二用户面网元之间的隧道在第一用户面网元上对应的端口。
可选的，第二用户面网元为第一终端设备所述的群组对应的5GLAN中的用户面网元。也即，第二用户面网元为第一终端设备所属群组中的终端设备提供服务。示例性的，第一用户面网元与第二用户面网元连接的隧道可以为N19隧道。
其中，第二端口的端口优先级和端口号用于确定第二端口的端口标识。
第二端口的Qos参数用于确定第二端口的带宽。第二端口的带宽用于确定第二端口的端口开销。可选的，第二端口的QoS参数可以包括但不限于：组(group)-AMBR。
上述第二端口的端口标识以及端口开销用于第一用户面网元进行STP选举或者STP维护的过程中。
应理解，对于第一用户面网元来说，第二端口的数量根据实际情况来确定。也即，第二端口可能存在一个或多个，或者第二端口可能一个都不存在。相应的，在第一用户面网元不存在第二端口的情况下，用于配置第一用户面网元激活STP功能时使用的参数不包括与第一用户面网元上第二端口相关的参数。
作为一种可能的实现方式，会话管理网元获取一个或多个存量LAN的配置信息。之后，会话管理网元根据一个或多个存量LAN的配置信息，确定第二端口的端口号和/或优先级。其中，存量LAN的配置信息包括存量LAN中各个设备上各个端口的端口号和/或优先级。
可选的，第二端口的优先级高于任意一个存量LAN中任意一个设备上端口的优先级。和/或，第二端口的端口号小于任意一个存量LAN中任意一个设备上端口的端口 号。这样一来，尽可能使得第二端口的PID可以小于任意一个存量LAN中任意一个设备上端口的PID。从而，在第一用户面网元为非根桥的情况下，增大第二端口被选举为指定端口或者根端口的概率。可以理解的是，在第二端口为指定端口或者根端口的情况下，第一用户面网元和第二用户面网元之间交互的数据，不用通过存量LAN中的其他设备进行转发，提高数据的安全性和保密性。
(4)与第一用户面网元上第三端口相关的参数，例如第三端口的端口号和/或第三端口的端口优先级。第三端口为第一用户面网元上用于与数据网络连接的端口。示例性的，第一用户面网元上用于与数据网络连接的端口可以为N6端口。
应理解，对于第一用户面网元来说，第三端口的数量根据实际情况来确定。也即，第三端口可能存在一个或多个，或者第三端口可能一个都不存在。相应的，在第一用户面网元不存在第三端口的情况下，用于配置第一用户面网元激活STP功能时使用的参数不包括与第一用户面网元上第三端口相关的参数。
对于第三端口来说，第一用户面网元一般根据本地存储的第三端口相关的配置信息，来计算第三端口的端口带宽，进而确定第三端口的端口开销。
可选的，上述用于配置第一用户面网元激活STP功能时使用的参数可以承载在不同的消息中。例如，第一端口的相关参数可以承载于第一终端设备的N4会话创建/修改请求消息中，第二端口的相关参数和第三端口的相关参数可以承载于第一终端设备所属群组的N4会话创建/修改请求消息中。
一种可能的设计中，在会话管理网元不为第一用户面网元配置第一端口的端口优先级和/或端口号的情况下，会话管理网元还可以向第一用户面网元发送第四指示信息，该第四指示信息可以用于指示第一用户面网元按照第一预设规则配置第一端口的端口号和/或优先级。示例性的，第一预设规则可以包括：第一端口的优先级高于任意一个存量LAN中任意一个设备上端口的优先级；和/或，第一端口的端口号小于任意一个存量LAN中任意一个设备上端口的端口号。
示例性的，第四指示信息可以有其他名称，例如PDU会话优先保留指示，对此不作限定。
一种可能的设计中，在会话管理网元不为第一用户面网元配置第二端口的端口优先级和/或端口号的情况下，会话管理网元还可以向第一用户面网元发送第五指示信息，该第五指示信息用于指示第一用户面网元按照第二预设规则配置第二端口的端口号和/或优先级。示例性的，第二预设规则可以包括：第二端口的优先级高于任意一个存量LAN中任意一个设备上端口的优先级；和/或，第二端口的端口号小于任意一个存量LAN中任意一个设备上端口的端口号。
示例性的，第五指示信息可以有其他名称，例如N19隧道优先保留指示，对此不作限定。
S104、第一用户面网元根据第一指示信息，激活STP功能。
作为一种可能的实现方式，第一用户面网元在接收到第一指示信息之后，获取用于激活STP功能时使用的参数。之后，第一用户面网元根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一用户面网元执行维护过程。
应理解，第一用户面网元可以自身配置全部地用于激活STP功能时使用的参数。或者，第一用户面网元可以从会话管理网元获取全部地用于激活STP功能时使用的参数。又或者，第一用户面网元可以从会话管理网元获取一部分地用于激活STP功能时使用的参数，以及自己配置另外一部分地用于激活STP功能时使用的参数。
举例来说，第一用户面网元激活STP功能时需要获知第一用户面网元的桥标识、第一端口的端口标识以及第一端口的QoS参数，但第一用户面网元仅从会话管理网元获取到第一用户面网元的桥标识和第一端口的QoS参数，从而第一用户面网元需要自身配置第一端口的端口标识。
下面对第一用户面网元执行STP选举过程的具体实现方式进行介绍。
(1)初始状态
第一用户面网元认为自己是根桥，在各个端口上发送配置BPDU报文，以进行根桥的选举。应理解，第一用户面网元至少配置有第一端口。可选的，第一用户面网元还配置有第二端口和/或第三端口。
对于第一端口发送出去的配置BPDU报文来说，该配置BPDU报文中根桥标识字段设置为第一用户面网元的BID，桥标识字段设置为第一用户面网元的BID，端口标识字段设置为第一端口的PID，根路径开销字段设置为0。
对于第二端口发送出去的配置BPDU报文来说，该配置BPDU报文中根桥标识字段设置为第一用户面网元的BID，桥标识字段设置为第一用户面网元的BID，端口标识字段设置为第二端口的PID，根路径开销字段设置为0。
对于第三端口发送出去的配置BPDU报文来说，该配置BPDU报文中根桥标识字段设置为第一用户面网元的BID，桥标识字段设置为第一用户面网元的BID，端口标识字段设置为第三端口的PID，根路径开销字段设置为0。
(2)根桥的选举
第一用户面网元通过接收网络中其他设备发送的配置BPDU报文，确定第一用户面网元的BID在网络中是否是最小的。在第一用户面网元的BID在网络中是最小的情况下，第一用户面网元为根桥。在第一用户面网元的BID在网络中不是最小的情况下，第一用户面网元为非根桥。
当第一用户面网元为根桥时，第一用户面网元上的各个端口均为指定端口。从而，第一用户面网元会将各个端口配置为forwarding状态。
当第一用户面网元为非根桥时，第一用户面网元还需要选举根端口和指定端口。
(3)根端口的选举
对于第一用户面网元上各个端口来说，端口会将接收到的配置BPDU报文与端口存储的配置BPDU报文进行比较。当接收到的配置BPDU报文的优先级低于端口存储的配置BPDU报文，端口会丢弃接收到的配置BPDU报文。如果接收到的配置BPDU报文的优先级高于端口存储的配置BPDU报文，则端口以接收到的配置BPDU报文更新存储的配置BPDU报文，或者说端口丢弃之前存储的配置BPDU报文，而存储刚接收到的配置BPDU报文。
第一用户面网元会将各个端口存储的配置BPDU报文进行比较，选出优先级最高的配置BPDU报文。相应的，存储该优先级最高的配置BPDU报文的端口即为第一用 户面网元的根端口。同时，除了根端口之外的其他端口设置为备用端口。
第一用户面网元还需从备用端口中选举出指定端口。
其中，配置BPDU报文的优先级可以按照以下维度依次比较：
1、根桥标识字段的取值。应理解，配置BPDU报文中根桥标识字段的取值越小，配置BPDU报文的优先级越高。
2、端口标识字段的取值。应理解，若两个配置BPDU报文的根桥标识字段的取值相同，端口标识字段的取值越小的配置BPDU报文的优先级越高。
3、根路径开销字段的取值。应理解，若两个配置BPDU报文在根桥标识字段以及端口标识字段上均相同则根路径开销字段的取值越小的配置BPDU报文的优先级越高。
(4)指定端口的选举
对于第一用户面网元上除了根端口之外的端口，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文。每条链路上都存在两个端口，当第一用户面网元的根端口之外的端口的目标配置BPDU报文的优先级高于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该端口为指定端口，从而该端口可以周期性发送目标配置BPDU报文。当该端口的目标配置BPDU报文的优先级低于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该端口为非指定端口。
可选的，对于第一用户面网元来说，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文，可以包括以下操作：
操作1、目标配置BPDU报文的根桥标识字段的取值即为根端口存储的配置BPDU报文的根桥标识字段的取值。
操作2、目标配置BPDU报文的根路径开销字段的取值根据根端口的本地路径开销以及根端口存储的配置BPDU报文中根路径开销字段的取值来确定。
操作3、目标配置BPDU报文的桥标识字段设置为第一用户面网元的BID，端口标识字段设置为该端口的端口标识。
应理解，第一用户面网元会将根端口和指定端口设置为forwarding状态。
在第一用户面网元选举出根端口和指定端口之后，第一用户面网元可以将除了根端口和指定端口之外的其他端口设置为阻塞状态。
可选的，第一用户面网元可以存储端口的PID、端口角色以及端口状态之间的对应关系。
示例性的，端口的PID、端口角色以及端口状态之间的对应关系可以存储在表2所示的列表中。
表2
端口PID 端口角色 端口状态
…… …… ……
可选的，第一用户面网元可以将第一对应关系存储在第一终端设备的PDU会话对应的N4会话上下文中，将第二对应关系和第三对应关系存储在第一终端设备所属群组的N4会话上下文中。其中，第一对应关系为第一端口的PID、端口角色以及端口状态之间的对应关系。第二对应关系为第二端口的PID、端口角色以及端口状态之间的 对应关系。第三对应关系为第三端口的PID、端口角色以及端口状态之间的对应关系。
基于图5所示的实施例，在第一终端设备发起PDU会话建立流程之后，第一用户面网元根据会话管理网元的指示，激活STP功能，以将5GLAN和存量LAN组成的网络修剪成无环路的树形网络拓扑结构，从而避免出现环路。
可选的，基于图5所示实施例的基础上，如图6所示，上述避免环路的方法还可以包括步骤S105-S106。
S105、会话管理网元向第一终端设备发送第二指示信息。相应的，第一终端设备接收会话管理网元发送的第二指示信息。
其中，第二指示信息用于指示第一终端设备激活STP功能。
可选的，第二指示信息还用于指示STP版本。示例性的，STP版本可以包括但不限于：RSTP和/或MSTP。
应理解，在第二指示信息还用于指示一个或多个STP版本的情况下，第一终端设备从第二指示信息所指示的STP版本中，选择激活STP功能时使用的一个STP版本。或者，在第二指示信息未指示STP版本的情况下，第一终端设备从自身支持的一个或多个STP版本，选择激活STP功能时使用的一个STP版本。
可选的，第二指示信息可以承载于一个新增的消息中。或者，第二指示信息可以承载于现有的消息中，例如，第二指示信息可以承载于PDU会话建立完成消息中。
作为一种可能的实现方式，在满足第二预设条件的情况下，会话管理网元向第一终端设备发送第二指示信息。
示例性的，第二预设条件可以包括以下一项或者多项：
条件2-1、会话管理网元获取到的运营商策略信息用于指示允许激活STP功能。
条件2-2、会话管理网元获取到的第一终端设备所属群组的签约信息包括用于指示允许激活STP功能的指示信息。
条件2-3、会话管理网元获取到的第一终端设备关联的策略及计费控制规则包括用于指示激活STP功能指示信息。
条件2-4、第一终端设备所属群组关联的5GLAN用户面拓扑存在多个用于与数据网络连接的端口；和/或，第一终端设备所属群组关联的5GLAN用户面拓扑中存在多个用户面网元。
上述条件2-1至条件2-4的具体介绍可以参考条件1-1至条件1-4，在此不再赘述。
条件2-5、第一终端设备支持STP功能。
在本申请实施例中，会话管理网元可以获取第一STP能力信息；进而，会话管理网元根据第一STP能力信息，确定第一终端设备是否支持STP功能。应理解，第一STP能力信息用于指示第一终端设备是否支持STP功能。
一种可能的设计中，会话管理网元可以从第一终端设备获取第一STP能力信息。例如，上述步骤S101提到的PDU会话建立请求消息可以包括第一STP能力信息。
另一种可能的设计中，会话管理网元可以从移动管理网元获取第一STP能力信息。例如，会话管理网元接收移动管理网元发送的N11消息，该N11消息可以包括第一STP能力信息。可选的，该N11消息还可以包括上述步骤S101提到的PDU会话建立请求消息。
可选的，移动管理网元可以在第一终端设备的注册流程中获取第一终端设备的STP能力信息。例如，移动管理网元接收第一终端设备的注册请求消息，该注册请求消息包括第一终端设备的STP能力信息。
可选的，会话管理网元还可以按照获取第一STP能力信息的方式来获取第一STP版本信息，第一STP版本信息用于指示第一终端设备支持的STP版本。从而，会话管理网元可以根据第一STP版本信息，从第一终端设备支持的STP版本中选择一个目标STP版本，并通过第二指示信息指示第一终端设备使用该目标STP版本。
上述第一STP能力信息和第一STP版本可以集成为同一个信息，或者为不同的两条信息，对此不作限定。
应理解，上述条件2-1至条件2-5仅是对第二预设条件的示例性说明，不构成具体限定。
可选的，会话管理网元还可以向第一终端设备发送用于配置第一终端设备激活STP功能时使用的参数。示例性的，用于配置第一终端设备激活STP功能时使用的参数可以包括以下一项或多项：第四端口的端口号、第四端口的优先级或第四端口的QoS参数。其中，第四端口为第一终端设备与第一用户面网元之间的所述PDU会话在第一终端设备上对应的端口。
其中，第四端口的端口号和第四端口的优先级用于确定第四端口的端口标识。
第四端口的QoS参数用于确定第四端口的端口带宽。第四端口的端口带宽用于确定第四端口的端口开销。示例性的，第四端口的QoS参数可以包括但不限于：session-AMBR、MFBR、和/或GFBR。
可选的，第二指示信息与用于配置第一终端设备激活STP功能时使用的参数封装在同一条消息中发送给第一终端设备。或者，第二指示信息与用于配置第一终端设备激活STP功能时使用的参数封装在不同的消息中分别发送给第一终端设备。
S106、第一终端设备根据第二指示信息，激活STP功能。
作为一种可能的实现方式，第一终端设备在接收到第二指示信息之后，获取用于激活STP功能时使用的参数。之后，第一用户面网元根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一终端设备执行维护过程。
应理解，第一终端设备可以从会话管理网元获取全部地用于激活STP功能时使用的参数。或者，第一终端设备可以从会话管理网元获取一部分地用于激活STP功能时使用的参数，以及自己配置另外一部分地用于激活STP功能时使用的参数。例如，第一终端设备配置自身的桥标识，以及从会话管理网元获取第四端口的端口号、第四端口的优先级以及第四端口的端口带宽。
下面对第一终端设备执行STP选举过程的具体实现方式进行介绍。
(1)初始状态
第一终端设备认为自己是根桥，在各个端口上发送配置BPDU报文，以进行根桥的选举。
对于第四端口发送出去的配置BPDU报文来说，该配置BPDU报文中根桥标识字段设置为第一终端设备的BID，桥标识字段设置为第一终端设备的BID，端口标识字 段设置为第四端口的PID，根路径开销字段设置为0。
(2)根桥的选举
第一终端设备通过接收网络中其他设备发送的配置BPDU报文，确定第一终端设备的BID在网络中是否是最小的。在第一终端设备的BID在网络中是最小的情况下，第一终端设备为根桥。在第一终端设备的BID在网络中不是最小的情况下，第一终端设备为非根桥。
当第一终端设备为根桥时，第一终端设备上的各个端口均为指定端口。从而，第一终端设备会将各个端口配置为forwarding状态。
当第一终端设备为非根桥时，第一终端设备还需要选举根端口和指定端口。
(3)根端口的选举
对于第一终端设备上各个端口来说，端口会将接收到的配置BPDU报文与端口存储的配置BPDU报文进行比较。当接收到的配置BPDU报文的优先级低于端口存储的配置BPDU报文，端口会丢弃接收到的配置BPDU报文。如果接收到的配置BPDU报文的优先级高于端口存储的配置BPDU报文，则端口以接收到的配置BPDU报文更新存储的配置BPDU报文，或者说端口丢弃之前存储的配置BPDU报文，而存储刚接收到的配置BPDU报文。
第一终端设备会将各个端口存储的配置BPDU报文进行比较，选出优先级最高的配置BPDU报文。相应的，存储该优先级最高的配置BPDU报文的端口即为第一终端设备的根端口。同时，除了根端口之外的其他端口设置为备用端口。
(4)指定端口的选举
对于第一终端设备上除了根端口之外的端口，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文。每条链路上都存在两个端口，当第一终端设备的根端口之外的端口的目标配置BPDU报文的优先级高于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该端口为指定端口，从而该端口可以周期性发送目标配置BPDU报文。当该端口的目标配置BPDU报文的优先级低于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该端口为非指定端口。
可选的，对于第一终端设备来说，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文，可以包括以下操作：
操作1、目标配置BPDU报文的根桥标识字段的取值即为根端口存储的配置BPDU报文的根桥标识字段的取值。
操作2、目标配置BPDU报文的根路径开销字段的取值根据根端口的本地路径开销以及根端口存储的配置BPDU报文中根路径开销字段的取值来确定。
操作3、目标配置BPDU报文的桥标识字段设置为第一终端设备的BID，端口标识字段设置为该端口的端口标识。
应理解，第一终端设备会将根端口和指定端口设置为forwarding状态。
在第一终端设备选举出根端口和指定端口之后，第一终端设备可以将除了根端口和指定端口之外的其他端口设置为阻塞状态。
应理解，本申请实施例不限制步骤S105-S106和步骤S103-S104之间的执行顺序。例如，可以先执行步骤S103-S104，再执行步骤S105-S106；或者，可以先执行步骤 S105-S106，再执行步骤S103-S104；又或者，同时执行步骤S105-S106和步骤S103-S104。
基于图6所示的实施例，在第一终端设备发起PDU会话建立流程之后，会话管理网元通过指示第一终端设备激活STP功能，从而将5GLAN和存量LAN组成的网络修剪成无环路的树形网络拓扑结构，以避免出现环路。
针对图6所示的实施例，下面结合具体示例进行举例说明。
作为一个示例，如图7(a)所示，在UE1发起PDU会话建立流程之后，SMF向UPF1发送第一指示信息，以使得UPF1激活STP功能；以及，SMF向UE1发送第二指示信息，以使得UE1激活STP功能。这样一来，网络中的各个设备运行STP，完成选举过程。其中，UPF1被选举为根桥，UPF1上UE1的PDU会话对应的端口设置为DP，UPF1上UE3的PDU会话对应的端口设置为DP。UE1上PDU会话对应的端口设置为RP，UE1上用于与UE2连接的端口设置为DP。UE2上用于与UE1连接的端口设置为RP。UE3上PDU会话对应的端口设置为RP，UE3上用于与UE4连接的端口设置为DP，UE3上用于与UE5连接的端口设置为DP。UE4上用于与UE3连接的端口设置为RP，UE4上用于与UE5连接的端口设置为DP。UE5上用于与UE3连接的端口设置为RP，UE5上用于与UE4连接的端口设置为AP。这样一来，使得网络中不会出现环路。
作为另一个示例，如图7(b)所示，在UE2发起PDU会话建立流程之后，SMF向UPF2发送第一指示信息，以使得UPF2激活STP功能；以及，SMF向UE2发送第二指示信息，以使得UE2激活STP功能。这样一来，网络中的各个设备运行STP，完成选举过程。其中，UPF1被选举为根桥。UPF1上各个端口均设置为DP。UPF2上用于与UPF1连接的端口设置为RP，UPF2上用于与UE2连接的端口设置为RP，UPF2上用于与DN1连接的端口设置为DP。UE1上用于与UPF1连接的端口设置为RP，UE1上其他端口均设置为DP。UE2上用于与UE1连接的端口设置为AP，UE2上用于与UPF2连接的端口设置为RP，UE2上用于与UE5连接的端口设置为DP，UE2上用于与UE6连接的端口设置为DP。DN1上用于与UPF1连接的端口设置为RP，DN1上用于与UPF2连接的端口设置为AP。这样一来，使得网络中不会出现环路。
在图7(a)和图7(b)中，以虚线来表示该链路在逻辑上被阻塞。
在终端设备的PDU会话释放之后，网络的拓扑结构发生了变化。这种情况下，如果5GLAN和存量LAN组成的网络还使用释放PDU会话之前运行STP生成的拓扑结构，则可能导致5GLAN和存量LAN组成的网络出现异常。
示例性的，如图8(a)所示，网络中通过运行STP被修剪为无环路的拓扑结构。具体的，UE1和UE2之间的链路在逻辑上阻断，UE6和UE8之间的链路在逻辑上阻断，DN1与UE7之间的链路在逻辑上阻断。但是，在UE1的PDU会话释放之后，UE1与UPF1之间的链路被释放，UPF1和UPF2之间的链路被释放，UPF1与DN1之间的链路被释放。这样导致UE1不能与网络中的其他设备(例如UE2)进行通信，DN1不能与网络中的其他设备(例如UE7)进行通信。
示例性的，如图8(b)所示，网络中通过运行STP被修剪为无环路的拓扑结构。具体的，UE1和UE2之间的链路在逻辑上阻断，DN1与UE7之间的链路在逻辑上阻断，UE5与UE6之间的链路在逻辑上阻断，UE6与UE8的链路在逻辑上阻断。在UE5 的PDU会话释放之后，UE5与UPF6之间的链路被释放。这样导致UE5不能与网络中的其他设备(例如UE6)进行通信。
应理解，上述图8(a)和图8(b)中以虚线表示两个设备之间的链路在逻辑上阻断。
针对终端设备的PDU会话释放导致5GLAN和存量LAN组成的网络出现异常的问题，本申请实施例提供一种避免环路的方法。如图9所示，该方法包括以下步骤：
S201、会话管理网元确定释放第一终端设备的PDU会话。
可选的，会话管理网元确定释放第一终端设备的PDU会话，包括以下情形之一：
情形一、会话管理网元接收到第一终端设备发送的PDU会话释放请求消息。
情形二、会话管理网元基于本地配置策略，确定释放PDU会话。
情形三、会话管理网元根据策略控制功能网元、移动管理网元等第三方网元的指示，确定释放第一终端设备的PDU会话。
S202、会话管理网元向第一用户面网元发送N4消息1。相应的，第一用户面网元接收会话管理网元发送的N4消息1。
其中，N4消息1用于请求释放PDU会话对应的N4会话。示例性的，N4消息1可以为N4会话释放请求消息，本申请实施例对此不作限定。
S203、第一用户面网元根据N4消息1，将第一端口设置为disable状态。
作为一种可能的实现方式，第一用户面网元根据N4消息1，在自身存储的端口信息表中将第一端口的端口状态设置disable状态。示例性的，端口信息表可以参考上述表2的示例。
应理解，第一用户面网元还会根据N4消息1，释放PDU会话对应的N4会话。
在本申请实施例中，在第一终端设备的PDU会话被释放之后，网络的拓扑结构发生了变化。从而，若第一用户面网元还为第一终端设备所属群组中的其他终端设备提供服务，则第一用户面网元可以触发网络重新进行收敛计算，以重新选举根桥、根端口以及指定端口。
S204、会话管理网元向第一终端设备发送PDU会话释放完成消息。相应的，第一终端设备接收会话管理网元发送的PDU会话释放完成消息。
S205、第一终端设备根据PDU会话释放完成消息，将第四端口设置为disable状态。
作为一种可能的实现方式，第一终端设备根据PDU会话释放完成消息，在自身存储的端口信息表中将第四端口的端口状态设置为disable状态。
在本申请实施例中，在第一终端设备的PDU会话被释放之后，网络的拓扑结构发生了变化。因此，第一终端设备可以触发网络重新进行收敛计算，以重新选举根桥、根端口以及指定端口。
可选的，若在第一终端设备的PDU会话被释放之后，第一用户面网元不为第一终端设备所属群组中的其他终端设备提供5GLAN服务，则所述避免环路的方法还可以包括以下步骤S206-S207。应理解，步骤S206-S207是可选的步骤。
S206、会话管理网元向第一用户面网元发送N4消息2。相应的，第一用户面网元接收会话管理网元发送的N4消息2。
其中，N4消息2用于释放第一终端设备所属群组的N4会话。
S207、第一用户面网元根据N4消息2，将第二端口和/或第三端口设置为disable状态。
作为一种可能的实现方式，当第一用户面网元配置有第二端口时，第一用户面网元根据N4消息2，在自身存储的端口信息表中将第二端口的端口状态设置为disable状态。以及，当第一用户面网元配置有第三端口时，第一用户面网元根据N4消息2，在自身存储的端口信息表中将第三端口的端口状态设置为disable状态。
基于图9所示的实施例，在第一终端设备的PDU会话释放之后，第一终端设备和第一用户面网元可以根据会话管理网元的指示，将相应的端口设置为disable状态，从而触发网络重新进行收敛计算，以重新选举根桥、根端口以及指定端口。
示例性的，以图10所示的场景来说明图9所示的实施例。如图10所示，在UE1的PDU会话释放之后，UPF1上用于与UE1连接的端口设置为disable状态，UPF1上用于与UPF2连接的端口设置为disable状态，UPF1上用于与DN1连接的端口设置为disable状态。UE1上用于与UPF1连接的端口设置为disable状态。UPF2上用于与UPF1连接的端口设置为disable状态。DN1上用于与UPF1连接的端口设置为disable状态。之后，网络重新进行收敛计算，从而使得UE1与UE2之间的链路连通，DN1与UE7之间的链路连通。
实施例二
如图11所示，为本申请实施例提供的一种避免环路的方法，该方法包括以下步骤：
S301、第一终端设备向会话管理网元发送PDU会话建立请求消息。相应的，会话管理网元接收第一终端设备发送的PDU会话建立请求消息。
S302、会话管理网元根据PDU会话建立请求消息，选择第一用户面网元。
其中，步骤S301-S302的具体介绍可以参考步骤S101-S102的相关描述，在此不再赘述。
S303、会话管理网元向第一终端设备发送第一消息。相应的，第一终端设备接收会话管理网元发送的第一消息。
其中，第一消息用于确定第一终端设备所在的LAN bridge的桥标识。示例性的，第一消息可以包括LAN bridge的桥优先级和/或桥MAC地址。或者，第一消息可以包括LAN bridge的桥标识。
在本申请实施例中，该LAN bridge包括第一终端设备和第一用户面网元。这样一来，第一终端设备和第一用户面网元可以作为一个整体(也即LAN bridge)来参与STP选举过程。从而，一方面，可以避免STP选举过程中，第一终端设备和第一用户面网元的PDU会话被逻辑阻断。另一方面，将两个及两个以上设备作为一个LAN bridge来参与STP选举过程，可以减少网络中LAN bridge(或者说交换机)的数量，从而简化网络的拓扑结构，以使得网络能够更快地实现收敛。
可选的，这种情况下，第一终端设备和第一用户面网元之间的PDU会话在第一终端设备上不被视为一个端口。同理，第一终端设备和第一用户面网元之间的PDU会话在第一终端设备上不被视为一个端口。
可选的，该LAN bridge还可以包括连接到第一用户面网元的第二终端设备。可选 的，该第二终端设备与第一终端设备属于同一个群组。
可选的，该LAN bridge还可以包括第二用户面网元，第二用户面网元为第一终端设备所属群组关联的5GLAN中的用户面网元。这种情况下，第一用户面网元和第二用户面网元之间的隧道在第一用户面网元上不被视为一个端口。同理，第一用户面网元和第二用户面网元之间的隧道在第二用户面网元上不被视为一个端口。
可选的，在LAN bridge还包括第二用户面网元的情况下，该LAN bridge还可以包括连接到第二用户面网元的第三终端设备。可选的，该第三终端设备可以和第一终端设备属于同一个群组。
一种可能的设计中，会话管理网元获取一个或多个存量LAN的配置信息。之后，会话管理网元根据一个或多个存量LAN的配置信息，确定LAN bridge的桥标识BID，例如桥优先级和/或桥MAC地址。其中，上述存量LAN可以是指与5GLAN连接的LAN。一个存量LAN的配置信息至少包括一个存量LAN的根桥的桥优先级和/或桥MAC地址。
可选的，LAN bridge的桥优先级高于任意一个存量LAN中根桥的桥优先级。和/或，LAN bridge的桥MAC地址小于任意一个存量LAN中根桥的桥MAC地址。这样一来，尽可能使得LAN bridge的BID小于任意一个存量LAN中根桥的BID。从而，在选举过程中，该LAN bridge可以被选举为根桥。
应理解，会话管理网元获取存量LAN的配置信息的具体实现方式可以参考上文，在此不再赘述。
可选的，第一消息还可以包括第二指示信息。第二指示信息的具体介绍可以参考上文中的描述，在此不再赘述。
可选的，步骤S303可以具体实现为：在满足第二预设条件的情况下，会话管理网元向第一终端设备发送第一消息。其中，第二预设条件可以参考上文中的描述，在此不再赘述。
S304、第一终端设备根据第一消息，激活STP功能。
作为一种可能的实现方式，第一终端设备在接收到第一消息之后，获取用于激活STP功能时使用的参数。之后，第一终端设备根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一终端设备执行维护过程。
可选的，第一终端设备确定LAN bridge的桥标识，包括以下情形：
情形一、在第一消息包括LAN bridge的桥优先级和桥MAC地址的情况下，第一终端设备可以根据第一消息所包括的LAN bridge的桥优先级和桥MAC地址，确定LAN bridge的桥标识。
情形二、在第一消息仅包括LAN bridge的桥优先级的情况下，第一终端设备根据本地配置的LAN bridge的桥MAC地址以及第一消息所包括的LAN bridge的桥优先级，来确定LAN bridge的桥标识。应理解，第一终端设备本地配置的LAN bridge的桥MAC地址会与第一用户面网元使用的LAN bridge的桥MAC地址相同，以保证两个设备确定的LAN bridge的桥标识相同。示例性的，第一终端设备本地配置的LAN bridge的桥MAC地址可以根据第一终端设备的出厂配置设置，或者根据第一终端设备与第一 用户面网元之间协商确定。
情形三、在第一消息仅包括LAN bridge的桥MAC地址的情况下，第一终端设备根据本地配置的LAN bridge的桥优先级以及第一消息所包括的LAN bridge的桥MAC地址，来确定LAN bridge的桥标识。应理解，第一终端设备本地配置的LAN bridge的桥优先级会与第一用户面网元使用的LAN bridge的桥优先级相同，以保证两个设备确定的LAN bridge的桥标识相同。示例性的，第一终端设备本地配置的LAN bridge的桥优先级可以根据第一终端设备的出厂配置设置，或者根据第一终端设备与第一用户面网元之间协商确定。
下面对LAN bridge中的第一终端设备执行STP选举过程的具体实现方式进行介绍。
(1)初始状态
第一终端设备认为LAN bridge为根桥，第一终端设备根据LAN bridge的桥标识通过第一终端设备的端口发送第一配置BPDU报文，该第一配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
此外，第一终端设备还通过第一终端设备的端口接收第二配置BPDU报文。并且，第一终端设备还通过第一终端设备与第一用户面网元之间的PDU会话，向第一用户面网元转发第二配置BPDU报文。从而，第一用户面网元可以获知第一终端设备周边设备的信息(例如桥标识、端口标识等)。
可选的，若第二配置BPDU报文的根桥标识字段的取值与LAN bridge的桥标识相同，说明该第二配置BPDU报文的发送端设备属于LAN bridge中的一部分，从而第一终端设备上接收到该第二配置BPDU报文的端口是用于LAN bridge中的设备进行通信的，也即该端口为内部端口。为了避免LAN bridge内部出现环路，因此第一终端设备可以将接收到该第二配置BPDU报文的端口设置为阻塞状态。
在本申请实施例中，为了便于描述，LAN bridge中一个设备上用于与LAN bridge中的另一个设备进行通信的端口简称为LAN bridge的内部端口。相应的，LAN bridge中一个设备上用于与不属于该LAN bridge的设备进行通信的端口简称为外部端口。
第一终端设备还通过第一终端设备与第一用户面网元之间的PDU会话，接收第一用户面网元转发的第三配置BPDU报文。应理解，第三配置BPDU报文是第一用户面网元的端口接收到的BPDU报文。从而，第一终端设备可以获知第一用户面网元周边设备的信息(例如桥标识、端口标识等)。
(2)根桥的选举
第一终端设备根据第二配置BPDU报文、第三配置BPDU报文以及第一配置BPDU报文，确定LAN bridge的桥角色。桥角色为根桥或者非根桥。
具体的，基于第二配置BPDU报文、第三配置BPDU报文以及第一配置BPDU报文，第一终端设备判断其所在的LAN bridge的桥标识是否是网络中最小的。在LAN bridge的桥标识在网络中是最小的情况下，LAN bridge即为根桥。否则，LAN bridge为非根桥。
当LAN bridge为根桥时，LAN bridge中的各个设备上外部端口的端口角色均为指定端口，端口状态均为转发状态。
当LAN bridge为非根桥时，LAN bridge中的各个设备需要选举根端口和指定端口。
可选的，内部端口可以设置为阻塞状态，避免LAN bridge内部产生环路。内部端口不参与根端口的选举以及指定端口的选举。
(3)根端口的选举
对于LAN bridge上各个外部端口来说，外部端口会将接收到的配置BPDU报文与外部端口存储的配置BPDU报文进行比较。当接收到的配置BPDU报文的优先级低于外部端口存储的配置BPDU报文，外部端口会丢弃接收到的配置BPDU报文。如果接收到的配置BPDU报文的优先级高于外部端口存储的配置BPDU报文，则外部端口以接收到的配置BPDU报文更新存储的配置BPDU报文，或者说外部端口丢弃之前存储的配置BPDU报文，而存储刚接收到的配置BPDU报文。
LAN bridge中的多个设备可以互通各自的外部端口所存储的配置BPDU报文。
LAN bridge中的设备(例如第一终端设备)会将LAN bridge中各个外部端口存储的配置BPDU报文进行比较，选出优先级最高的配置BPDU报文。相应的，存储该优先级最高的配置BPDU报文的外部端口即为根端口。举例来说，若存储该优先级最高的配置BPDU报文的外部端口为第一终端的端口，即LAN bridge的根端口为第一终端设备的端口。
可以理解的是，由于LAN bridge上只存在一个根端口，因此LAN bridge中多个设备中存在一个设备有根端口，其他设备上没有根端口。
LAN bridge中除了根端口之外的其他外部端口设置为备用端口。对于第一终端设备来说，若第一终端设备上存在根端口，则第一终端设备上除了根端口之外的其他外部端口为备用端口；或者，若第一终端设备上不存在根端口，则第一终端设备上所有外部端口为备用端口。
备用端口需要参与以下指定端口的选举。
(4)指定端口的选举
对于第一终端设备上除了LAN bridge的根端口之外的端口，基于LAN bridge的根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文。每条链路上都存在两个端口，当第一终端设备上的备用端口的目标配置BPDU报文的优先级高于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该备用端口为指定端口。当该备用端口的目标配置BPDU报文的优先级低于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该备用端口为非指定端口。
可选的，对于第一终端设备来说，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文，可以包括以下操作：
操作1、目标配置BPDU报文的根桥标识字段的取值即为LAN bridge的根端口存储的配置BPDU报文的根桥标识字段的取值。
操作2、目标配置BPDU报文的根路径开销字段的取值根据根端口的本地路径开销以及根端口存储的配置BPDU报文中根路径开销字段的取值来确定。
操作3、目标配置BPDU报文的桥标识字段设置为第一终端设备的BID，端口标识字段设置为该端口的端口标识。
应理解，在LAN bridge的根端口是第一终端设备的端口的情况下，第一终端设备会将LAN bridge的根端口和第一终端设备上的指定端口设置为转发状态。在第一终端 设备选举出LAN bridge的根端口和指定端口之后，第一终端设备可以将除了LAN bridge的根端口和第一终端设备上的指定端口之外的其他端口设置为阻塞状态。
在LAN bridge的根端口不是第一终端设备的端口的情况下，第一终端设备会将第一终端设备上的指定端口设置为转发状态，以及将除了指定端口之外的其他端口设置为阻塞状态。
基于图11所示的实施例，在第一终端设备建立PDU会话访问5GLAN服务的情况下，会话管理网元通过向第一终端设备发送第一消息，以使得第一终端设备确定其所在的LAN bridge的桥标识。进而，第一终端设备可以作为该LAN bridge中的一部分来参与STP选举，以避免网络中出现环路。
可选的，基于图11所示实施例的基础上，如图12所示，该避免环路的方法还可以包括步骤S305-S306。
S305、会话管理网元向第一用户面网元发送第二消息。相应的，第一用户面网元接收会话管理网元发送的第二消息。
可选的，第二消息可以用于确定LAN bridge的桥标识BID。例如，第二消息可以包括LAN bridge的桥标识或桥优先级和/或桥MAC地址。或者，第二消息可以包括LAN bridge的桥标识。
可选的，第二消息可以包括第一指示信息，第一指示信息用于指示第一用户面网元激活STP功能。其中，第一指示信息的相关描述可以参考上文，在此不再赘述。
可选的，第二消息还可以包括第一终端设备所属群组的标识。
可选的，在LAN bridge不包括第二用户面网元的情况下，第二消息还可以包括第二端口相关的参数。示例性的，第二端口相关的参数可以包括：第二端口的端口号、端口优先级以及QoS参数。其中，第二端口的Qos参数用于确定第二端口的带宽。第二端口的带宽用于确定第二端口的端口开销。可选的，第二端口的QoS参数可以包括但不限于：group-AMBR。
可选的，步骤S305可以具体实现为：在满足第一预设条件的情况下，会话管理网元向第一用户面网元发送第二消息。其中，第一预设条件可以参考上文中的描述，在此不再赘述。
S306、第一用户面网元根据第二消息，激活STP功能。
作为一种可能的实现方式，第一用户面网元在接收到第二消息之后，获取用于激活STP功能时使用的参数。之后，第一用户面网元根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一用户面网元执行维护过程。
可选的，第一用户面网元确定LAN bridge的桥标识，包括以下情形：
情形一、在第二消息包括LAN bridge的桥优先级和桥MAC地址的情况下，第一用户面网元可以根据第二消息所包括的LAN bridge的桥优先级和桥MAC地址，确定LAN bridge的桥标识。
情形二、在第二消息仅包括LAN bridge的桥优先级的情况下，第一用户面网元根据本地配置的LAN bridge的桥MAC地址以及第二消息所包括的LAN bridge的桥优先级，来确定LAN bridge的桥标识。应理解，第一用户面网元本地配置的LAN bridge 的桥MAC地址会与第一终端设备使用的LAN bridge的桥MAC地址相同，以保证两个设备确定的LAN bridge的桥标识相同。示例性的，第一用户面网元本地配置的LAN bridge的桥MAC地址可以根据第一用户面网元的出厂配置设置，或者根据第一终端设备与第一用户面网元之间协商确定。
情形三、在第二消息仅包括LAN bridge的桥MAC地址的情况下，第一用户面网元根据本地配置的LAN bridge的桥优先级以及第二消息所包括的LAN bridge的桥MAC地址，来确定LAN bridge的桥标识。应理解，第一用户面网元本地配置的LAN bridge的桥优先级会与第一终端设备使用的LAN bridge的桥优先级相同，以保证两个设备确定的LAN bridge的桥标识相同。示例性的，第一用户面网元本地配置的LAN bridge的桥优先级可以根据第一终端设备的出厂配置设置，或者根据第一终端设备与第一用户面网元之间协商确定。
情形四、在第二消息不包括LAN bridge的桥优先级和桥MAC地址的情况下，第一用户面网元可以根据本地配置的桥优先级和桥MAC地址，确定LAN bridge的桥标识。
下面对LAN bridge中的第一用户面网元执行STP选举过程的具体实现方式进行介绍。
(1)初始状态
第一用户面网元认为LAN bridge为根桥，第一用户面网元根据LAN bridge的桥标识通过第一用户面网元的端口发送第四配置BPDU报文，该第四配置BPDU报文中根桥标识字段的取值设置为LAN bridge的桥标识。
此外，第一用户面网元还通过第一用户面网元的端口接收第三配置BPDU报文。并且，第一用户面网元还通过第一终端设备与第一用户面网元之间的PDU会话，向第一终端设备透传(或者说转发)第三配置BPDU报文。从而，第一终端设备可以获知第一用户面网元周边设备的等信息(例如桥标识、端口标识等)。
第一用户面网元还通过第一终端设备与第一用户面网元之间的PDU会话，接收第一终端设备透传的第二配置BPDU报文。应理解，第二配置BPDU报文是第一用户面网元的端口接收到的BPDU报文。从而，第一用户面网元可以获知第一终端设备周边设备的信息(例如桥标识、端口标识等)。
(2)根桥的选举
第一用户面网元根据第二配置BPDU报文、第三配置BPDU报文以及第四配置BPDU报文，确定LAN bridge的桥角色。具体的，基于第二配置BPDU报文、第三配置BPDU报文以及第四配置BPDU报文，第一用户面网元判断第一用户面网元所在的LAN bridge的桥标识是否是网络中最小的。在LAN bridge的桥标识在网络中是最小的情况下，LAN bridge即为根桥。否则，LAN bridge为非根桥。
在本申请实施例中，为了便于描述，LAN bridge中一个设备上用于与LAN bridge中的另一个设备进行通信的端口简称为内部端口。相应的，LAN bridge中一个设备上用于与不属于该LAN bridge的设备进行通信的端口简称为外部端口。
当LAN bridge为根桥时，LAN bridge中的各个设备上的外部端口角色均为指定端口，端口状态均为转发状态。
当LAN bridge为非根桥时，LAN bridge中的各个设备需要选举根端口和指定端口。
可选的，LAN bridge的内部端口可以设置为阻塞状态，避免LAN bridge内部产生环路。LAN bridge的内部端口不参与根端口的选举以及指定端口的选举。
(3)根端口的选举
对于LAN bridge各个外部端口来说，外部端口会将接收到的配置BPDU报文与该外部端口存储的配置BPDU报文进行比较。当接收到的配置BPDU报文的优先级低于端口存储的配置BPDU报文，外部端口会丢弃接收到的配置BPDU报文。如果接收到的配置BPDU报文的优先级高于外部端口存储的配置BPDU报文，则外部端口以接收到的配置BPDU报文更新存储的配置BPDU报文，或者说外部端口丢弃之前存储的配置BPDU报文，而存储刚接收到的配置BPDU报文。
LAN bridge中的多个设备可以互通各自的外部端口所存储的配置BPDU报文。
LAN bridge中的设备(例如第一用户面网元)会将LAN bridge中各个外部端口存储的配置BPDU报文进行比较，选出优先级最高的配置BPDU报文。相应的，存储该优先级最高的配置BPDU报文的外部端口即为根端口。
LAN bridge中除了根端口之外的其他外部端口设置为备用端口。对于第一用户面网元来说，若第一用户面网元上存在根端口，则第一用户面网元上除了根端口之外的其他外部端口为备用端口；或者，若第一用户面网元上不存在根端口，则第一用户面网元上所有外部端口为备用端口。
备用端口需要参与以下指定端口的选举。
(4)指定端口的选举
对于第一用户面网元上除了LAN bridge的根端口之外的端口，基于LAN bridge的根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文。每条链路上都存在两个端口，当第一用户面网元的备用端口的目标配置BPDU报文的优先级高于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该备用端口为指定端口。当该备用端口的目标配置BPDU报文的优先级低于从链路连接的相邻设备的端口接收到的配置BPDU报文时，确定该备用端口为非指定端口。
可选的，对于第一用户面网元来说，基于根端口存储的配置BPDU报文，生成该端口的目标配置BPDU报文，可以包括以下操作：
操作1、目标配置BPDU报文的根桥标识字段的取值即为LAN bridge的根端口存储的配置BPDU报文的根桥标识字段的取值。
操作2、目标配置BPDU报文的根路径开销字段的取值根据根端口的本地路径开销以及根端口存储的配置BPDU报文中根路径开销字段的取值来确定。
操作3、目标配置BPDU报文的桥标识字段设置为第一用户面网元的BID，端口标识字段设置为该端口的端口标识。
应理解，在LAN bridge的根端口是第一用户面网元的端口的情况下，第一用户面网元会将LAN bridge的根端口和第一用户面网元上的指定端口设置为转发状态。在第一用户面网元选举出LAN bridge的根端口和指定端口之后，第一用户面网元可以将除了LAN bridge的根端口和第一用户面网元上的指定端口之外的其他端口设置为阻塞状态。
在LAN bridge的根端口不是第一用户面网元的端口的情况下，第一用户面网元会将第一终端设备上的指定端口设置为转发状态，以及将除了指定端口之外的其他端口设置为阻塞状态。
基于图12所示的实施例，在第一终端设备建立PDU会话访问5GLAN服务的情况下，会话管理网元可以向第一用户面网元发送第二消息，以使得第一用户面网元将自身作为LAN bridge中的一部分来进行STP选举，以避免网络中出现环路。
实施例三
如图13所示，为本申请实施例提供的一种避免环路的方法，该方法包括以下步骤：
S401、应用功能网元接收第三消息。
其中，第三消息包括第一容器。第一容器包括第一终端设备相关的STP信息。示例性的，第一终端设备相关的STP信息可以包括第一STP能力信息和/或第一STP版本信息。其中，第一STP能力信息可以用于指示第一终端设备是否支持STP功能。第一STP版本信息可以用于指示第一终端设备支持的STP版本。应理解，实际应用中，第一STP能力信息和第一STP版本信息可以是分别单独的两条信息，也可以集成为一条信息，对此不作限定。
可选的，第三消息还可以包括第二容器。第二容器包括第一用户面网元相关的STP信息。示例性的，第一用户面网元相关的STP信息可以包括第二STP能力信息和/或第二STP版本信息。其中，第二STP能力信息可以用于指示第一用户面网元是否支持STP功能。第二STP版本信息可以用于指示第一用户面网元支持的STP版本。应理解，实际应用中，第二STP能力信息和第二STP版本信息可以是分别单独的两条信息，也可以集成为一条信息，对此不作限定。
可选的，第三消息或者第二容器还可以包括LAN bridge的桥标识，例如桥优先级和/或桥MAC地址。应理解，第三消息或者第二容器所包括的LAN bridge的桥标识可以是提供给应用功能网元参考的候选的桥优先级，而不是LAN bridge实际使用的桥标识。
也即，应用功能网元可以以第三消息或者第二容器所包括的LAN bridge的桥标识，来作为LAN bridge的实际使用的桥标识；或者，应用功能网元也可以自己来分配LAN bridge的实际使用的桥标识。本申请实施例对此不作限定。
在本申请实施例中，该LAN bridge包括第一终端设备和第一用户面网元。这种情况下，第一终端设备和第一用户面网元之间的PDU会话在第一终端设备上不被视为一个端口。同理，第一终端设备和第一用户面网元之间的PDU会话在第一终端设备上不被视为一个端口。
可选的，该LAN bridge还可以包括连接到第一用户面网元的第二终端设备。可选的，该第二终端设备与第一终端设备属于同一个群组。
可选的，该LAN bridge还可以包括第二用户面网元，第二用户面网元为第一终端设备所属群组关联的5GLAN中的用户面网元。这种情况下，第一用户面网元和第二用户面网元之间的隧道在第一用户面网元上不被视为一个端口。同理，第一用户面网元和第二用户面网元之间的隧道在第二用户面网元上不被视为一个端口。
可选的，在LAN bridge还包括第二用户面网元的情况下，该LAN bridge还可以 包括连接到第二用户面网元的第三终端设备。可选的，该第三终端设备可以和第一终端设备属于同一个群组。
可选的，在第三消息包括第一容器和第二容器的情况下，应用功能网元可以获知第一终端设备与第一用户网元之间的关系。也即，应用功能网元可以获知第一终端设备连接到第一用户面网元。
可选的，在第三消息仅包括第一容器不包括第二容器的情况下，第三消息还可以包括第一用户面网元的标识(例如设备标识、第一用户面网元所在LAN bridge的桥标识等)，以使得应用功能网元可以获知第一终端设备连接到第一用户面网元。
可选的，第三消息还可以包括第一终端设备所属群组的标识。
可选的，步骤S401可以具体实现为：应用功能网元接收来自于会话管理网元的第三消息。例如，应用功能网元可以通过策略控制功能网元或者网络开放功能网元接收来自于会话管理网元的第三消息。
一种可能的设计中，会话管理网元通过策略控制功能网元向应用功能网元发送第三消息。具体的，第三消息的传输路径可以为：会话管理网元->策略控制功能网元->应用功能网元。
应理解，本申请实施例以“->”表示信息的传递方向。例如，设备1->设备2，表示信息从设备1发送到设备2。
另一种可能的设计中，会话管理网元通过策略控制功能网元和网络开放功能网元向应用功能网元发送第三消息。具体的，第三消息的传输路径可以为：会话管理网元->策略控制功能网元->网络开放功能网元->应用功能网元。
应理解，在第三消息的传输过程中，传输第三消息的中间网元(例如策略控制功能网元或者网络开放功能网元)可以对第三消息进行相应的处理(例如修改第三消息的名称，增加或者修改第三消息携带的内容)。
S402、应用功能网元向第一终端设备发送第三容器。相应的，第一终端设备接收应用功能网元发送的第三容器。
其中，第三容器用于确定第一终端设备所在的LAN bridge的桥标识。示例性的，第三容器可以包括LAN bridge的桥标识或桥优先级和/或桥MAC地址。应理解，桥标识由桥优先级和桥MAC地址构成。或者，第三容器可以包括LAN bridge的桥标识。
可选的，第三容器还包括第二指示信息。第二指示信息用于指示第一终端设备激活STP功能。第二指示信息的具体介绍可以参考前文，在此不再赘述。
可选的，步骤S402可以具体实现为：在满足第三预设条件的情况下，应用功能网元向第一终端设备发送第三容器。
示例性的，第三预设条件包括以下一项或者多项：
条件3-1、应用功能网元获取到的运营商策略信息用于指示允许激活STP功能。
在本申请实施例中，应用功能网元可以从操作维护管理(operation administration and maintenance，OAM)系统获取运营商或第三方策略信息。可选的，该策略信息可以应用于整个运营商网络，或者该运营商策略信息应用于第一终端设备所属的群组。
条件3-2、第一终端设备所属群组关联的5GLAN用户面拓扑存在多个用于与数据网络连接的端口；和/或，第一终端设备所属群组关联的5GLAN用户面拓扑中存在多 个用户面网元。
条件3-3、第三消息包括用于指示激活STP功能的指示信息。
条件3-4、第一终端设备支持STP功能。
其中由于第一容器可能包括第一STP能力信息，因此应用功能管理网元可以根据第一STP信息，确定第一终端设备是否支持STP功能。
应理解，上述条件3-1至条件3-4仅是对第三预设条件的示例，不构成具体限定。
S403、第一终端设备根据第三容器，激活STP功能。
作为一种可能的实现方式，第一终端设备在接收到第三容器之后，获取用于激活STP功能时使用的参数。之后，第一终端设备根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一终端设备执行维护过程。
其中，第一终端设备执行STP选举过程的具体细节可以参考图11所示实施例的步骤S304，在此不再赘述。
基于图13所示的实施例，应用功能网元通过向第一终端设备发送第三容器，以使得第一终端设备确定其所在的LAN bridge的桥标识。进而，第一终端设备可以作为该LAN bridge中的一部分来参与STP选举，以避免网络中出现环路。
可选的，基于图13所示实施例，如图14所示，该避免环路的方法还包括步骤S404-S405。
S404、应用功能网元向第一用户面网元发送第四容器。相应的，第一用户面网元接收应用功能网元发送的第四容器。
可选的，第四容器可以用于确定LAN bridge的桥标识BID。例如，第四容器可以包括LAN bridge的桥标识或桥优先级和/或桥MAC地址。应理解，桥标识由桥优先级和桥MAC地址构成。或者，第四容器包括LAN bridge的桥标识。
可选的，第四容器可以包括第一指示信息，第一指示信息用于指示第一用户面网元激活STP功能。其中，第一指示信息的具体描述可以参考前文，在此不再赘述。
可选的，步骤S405可以具体实现为：在满足第四预设条件的情况下，应用功能网元向第一用户面网元发送第四容器。
示例性的，第四预设条件包括以下一项或者多项：
条件4-1、应用功能网元获取到的运营商或第三方的策略信息用于指示允许激活STP功能。可选的，该策略信息可以适用于整个运营商网络，或者该策略信息与第一终端设备所属群组关联。
条件4-2、第一终端设备所属群组关联的5GLAN用户面拓扑存在多个用于与数据网络连接的端口；和/或，第一终端设备所属群组关联的5GLAN用户面拓扑中存在多个用户面网元。
条件4-3、第三消息包括用于指示激活STP功能的指示信息。
条件4-4、第一用户面网元支持STP功能。
可选的，由于第二容器可能包括第二STP能力信息，因此应用功能网元可以根据第二STP能力信息，确定第一用户面网元是否支持STP功能。
应理解，上述条件4-1至条件4-4仅是对第四预设条件的示例，不构成具体限定。
S405、第一用户面网元根据第四容器，激活STP功能。
作为一种可能的实现方式，第一用户面网元在接收到第四容器之后，获取用于激活STP功能时使用的参数。之后，第一用户面网元根据激活STP功能时使用的参数，激活STP功能，以进行STP选举过程。以及，在STP选举过程之后，第一用户面网元执行维护过程。
可选的，在在LAN bridge不包括第二用户面网元的情况下，第一用户面网元可以从会话管理网元获取第二端口相关的参数。示例性的，第二端口相关的参数可以包括：第二端口的端口号、端口优先级以及QoS参数。其中，第二端口的Qos参数用于确定第二端口的带宽。第二端口的带宽用于确定第二端口的端口开销。可选的，第二端口的QoS参数可以包括但不限于：组(group)-AMBR。
应理解，LAN bridge中的第一用户面网元执行STP选举过程的具体细节可以参考图12所示实施例中的步骤S306，对此不再赘述。
基于图14所示的实施例，应用功能网元通过向第一用户面网元发送第四容器，以使得第一用户面网元将自身作为LAN bridge中的一部分来进行STP选举，以避免网络中出现环路。
下面结合具体示例来对图14所示实施例进行具体介绍。
如图15所示，为本申请实施例提供的一种避免环路的方法，该方法包括以下步骤：
S501、第一终端设备向会话管理网元发送PDU会话建立请求消息。相应的，会话管理网元接收第一终端设备发送的PDU会话建立请求消息。
其中，PDU会话建立请求消息用于请求建立PDU会话。PDU会话建立请求消息包括：第一容器以及第一终端设备所属群组的标识。第一容器的具体描述可以参考上文，在此不再赘述。
S502、会话管理网元根据PDU会话建立请求消息，选择第一用户面网元。
其中，步骤S502的具体描述可以参考步骤S102的介绍，在此不再赘述。
S503(可选的)、会话管理网元获取第二容器。
作为一种可能的实现方式，会话管理网元接收第一用户面网元发送的N4消息，该N4消息包括第二容器。可选的，该N4消息还可以包括第一终端设备所属群组的标识。
示例性的，该N4消息可以为N4报告(report)消息或N4会话响应消息，对此不作限定。
一种可能的设计中，在第一终端设备是群组中第一个连接到第一用户网元的情况下，第一用户面网元可以主动或者在会话管理网元的指示下向会话管理网元发送包含第二容器的N4消息。
另一种可能的设计中，在第一终端设备不是群组中第一个连接到第一用户面网元的情况下，第一用户面网元可以在桥信息(例如桥优先级或者桥MAC地址)、端口信息等发生变更的情况下，主动向会话管理网元发送包含第二容器的N4消息。
S504、会话管理网元向应用功能网元发送第三消息。相应的，应用功能网元接收会话管理网元发送的第三消息。
其中，第三消息的相关描述可以参考上文，在此不再赘述。
作为一种可能的实现方式，在满足第二预设条件的情况下，会话管理网元可以向应用功能网元发送第三消息。
可选的，在满足第二预设条件的情况下，会话管理网元发送的第三消息可以包括用于指示激活STP功能的指示信息。
一种可能的设计中，会话管理网元通过策略控制功能网元向应用功能网元发送第三消息。具体的，第三消息的传输路径可以为：会话管理网元->策略控制功能网元->应用功能网元。
另一种可能的设计中，会话管理网元通过策略控制功能网元和网络开放功能网元向应用功能网元发送第三消息。具体的，第三消息的传输路径可以为：会话管理网元->策略控制功能网元->网络开放功能网元->应用功能网元。
S505、应用功能网元向会话管理网元发送第四消息。相应的，会话管理网元接收应用功能网元发送的第四消息。
其中，第四消息可以包括第三容器。
可选的，第四消息还可以包括第四容器。
可选的，第四消息还可以包括第一终端设备所属群组的标识。
一种可能的设计中，应用功能网元通过策略控制功能网元向会话管理网元发送第四消息。具体的，第四消息的传输路径可以为：应用功能网元->策略控制功能网元->会话管理网元。
另一种可能的设计中，应用功能网元通过策略控制功能网元和网络开放功能网元向会话管理网元发送第四消息。具体的，第四消息的传输路径可以为：应用功能网元->网络开放功能网元->策略控制功能网元->会话管理网元。
应理解，在第四消息的传输过程中，传输第四消息的中间网元(例如策略控制功能网元或者网络开放功能网元)可以对第四消息进行相应的处理(例如修改第四消息的名称，增加或者修改第四消息携带的内容)。
S506、会话管理网元根据第四消息，向第一终端设备发送第三容器。
S507、第一终端设备根据第三容器，激活STP功能。
可选的，在第四消息包括第四容器的情况下，还可以执行下述步骤S508-S509。
S508(可选的)、会话管理网元根据第四消息，向第一用户面网元发送第四容器。
可选的，会话管理网元还可以向第一用户面网元发送取第二端口相关的参数。示例性的，第二端口相关的参数可以包括：第二端口的端口号、端口优先级以及QoS参数。
可选的，第二端口相关的参数和第四容器可以封装在同一条N4消息中，或者封装在不同的N4消息中分别发送。
S509(可选的)、第一用户面网元根据第四容器，激活STP功能。
基于图15所示的实施例，会话管理网元负责转发第一终端设备和应用功能网元之间的容器，以及第一用户面网元和应用功能网元之间的容器。从而，应用功能网元可以通过第三容器使得第一终端设备激活STP功能，以及通过第四容器使得第一用户面网元激活STP功能。
下面结合附图来对LAN bridge执行STP选举过程进行举例说明。
作为一个示例，如图16(a)所示，在UE1和UE2建立PDU会话接入5GLAN的情况下，UE1、UE2以及UPF1可以构成一个LAN bridge来参与STP选举。应理解，UE1与UE2之间通信的端口即为LAN bridge的内部端口，从而UE1上用于与UE2通信的端口将被设置为阻塞状态，UE2上用于与UE1通信的端口将被设置为阻塞状态，从而UE1和UE2之间的链路将在逻辑上阻塞。
在STP选举过程中，UPF1可以向UE1和UE2透传其从DN1接收到的配置BPDU报文，UE2可以向UPF1和UE1透传其从UE3或UE4接收到的配置BPDU报文。
在图16(a)中，UE1、UE2以及UPF1所构成一个LAN bridge被选举为根桥，因而LAN bridge的所有外部端口设置为DP。也即，UPF1上用于与DN1通信的端口设置为DP，UE2上用于与UE3通信的端口设置为DP，UE2上用于与UE4通信的端口设置为DP。
相对应的，DN1上用于与UPF1通信的端口被选举为RP，DN1上用于与UE4通信的端口被选举为AP。UE3上用于与UE2通信的端口被选举为RP。UE4上用于与DN1通信的端口被选举为AP，UE4上用于与UE2通信的端口被选举为RP。
从而，由图16(a)可见，UE4与DN1通信的链路在逻辑上被阻塞。从而，整个网络中不存在环路。
作为另一个示例，如图16(b)所示，在UE1和UE2建立PDU会话接入5GLAN之后，UE1、UE2以及UPF1可以构成一个LAN bridge 1来参与STP选举。类似的，在UE5和UE6建立PDU会话接入5GLAN之后，UE5、UE6和UPF可以构成一个LAN bridge 2来参与STP选举。其中，UPF2和UPF1之间的N19隧道在UPF2和UPF1上均被视为端口。
应理解，UE1与UE2之间通信的端口即为LAN bridge 1的内部端口，从而UE1上用于与UE2通信的端口将被设置为阻塞状态，UE2上用于与UE1通信的端口将被设置为阻塞状态，从而UE1和UE2之间的链路将在逻辑上阻塞。
在STP选举过程中，对于LAN bridge1，UPF1可以向UE1和UE2透传其从DN1或UPF2接收到的配置BPDU报文，UE2可以向UPF1和UE1透传其从UE6、UE3或UE4接收到的配置BPDU报文。对于LAN bridge2，UPF2可以向UE5和UE6透传其从DN1或UPF1接收到的配置BPDU报文，UE6可以向UPF2和UE5透传其从UE2接收到的配置BPDU报文。
在图16(b)中，LAN bridge 2被选举为根桥，从而LAN bridge 2的所有外部端口设置为DP。也即，UPF2用于与UPF1的端口被设置为DP，UPF2用于与DN1通信的端口被设置为DP，UE6用于与UE2通信的端口被设置为DP。
相应的，UPF1上用于与UPF2通信的端口被设置为RP，UPF1上用于DN1通信的端口被设置为DP。UE2上用于与UE3通信的端口设置为DP，UE2上用于与UE4通信的端口设置为DP，UE2上用于与UE6通信的端口设置为AP。
DN1上用于与UPF1通信的端口被选举为AP，DN1上用于与UPF2通信的端口被选举为RP。UE3上用于与UE2通信的端口被选举为RP。UE4上用于与DN1通信的端口被选举为AP，UE4上用于与UE2通信的端口被选举为RP。
从而，如图16(b)所示，DN1与UPF1之间的链路在逻辑上被阻塞，UE2和UE6 之间的链路在逻辑上被阻塞。从而，整个网络中不存在环路。
在一些场景下，用户面网元需要激活STP功能，以保证网络中不出现环路。在另一些场景下，用户面网元可以不激活STP功能，以减少接收到BPDU报文，减轻用户面网元处理报文的压力。因此，有必要对用户面网元去激活STP功能进行相应的管理。
对此，本申请实施例提供一种STP功能的管理方法。如图17所示，该方法包括以下步骤：
S601、会话管理网元向第一用户面网元发送第三指示信息。相应的，第一用户面网元接收会话管理网元发送的第三指示信息。
其中，第三指示信息用于指示去激活STP功能。具体的，第三指示信息用于指示第一用户面网元去激活STP功能。
一种可能的设计中，第三指示信息用于指示第一用户面网元针对第一终端设备所属群组去激活STP功能。可选的，这种情况下，第三指示信息包括第一终端设备所属群组的标识。
可选的，第三指示信息可以承载于N4消息中。
作为一种可能的实现方式，当会话管理网元确定第一用户面网元不为第一终端设备所属群组中的任意一个终端设备提供5GLAN服务时，会话管理网元向第一用户面网元发送第三指示信息。
作为另一种可能的实现方式，在第一终端设备释放PDU会话的情况下，会话管理网元向第一用户面网元发送第三指示信息。
S602、第一用户面网元根据第三指示信息，去激活STP功能。
可选的，第一用户面网元去激活STP功能，可以实现为：第一用户面网元将第一端口、第二端口以及第三端口均设置为disable状态。
基于图17所示的实施例，第一用户面网元可以根据会话管理网元的指示，去激活STP功能。从而，第一用户面网元可以避免持续接收到不必要的BPDU报文。
应理解，图17所示的实施例可以与上述图5,图6,图9,图11,图12,图13,图14或图15所示实施例中的任意一个相互结合使用。
可选的，本申请实施例中“激活STP功能”可以替换为“运行STP”、“开启STP功能”等概念。相应的，“去激活STP功能”可以替换为“停止运行STP”、“关闭STP功能”等概念。
上述图5,图6,图11,图12,或图15所示实施例仅对PDU会话建立流程中的一部分步骤进行了介绍。应理解，PDU会话建立流程还可以包括其他步骤。PDU会话建立流程中的其他步骤可以参考现有技术中的描述，在此不予赘述。
上述图9所示实施例中仅对PDU会话释放流程中的一部分步骤进行了介绍。应理解，PDU会话释放流程还可以包括其他步骤。PDU会话释放流程中的其他步骤可以参考现有技术中的描述，在此不予赘述。
应理解，上述各个网元的名称、消息的名称以及信息的名称仅是示例，具体实现中也可以是其他名称，本申请实施例对此不作限定。
在本申请实施例中，端口可以是指物理端口或者逻辑端口，对此不作限定。
上述主要从方法的角度对本申请实施例提供的方案进行了介绍。可以理解的是， 通信装置(例如会话管理网元、应用功能网元、第一终端设备或第一用户面网元)为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。结合本申请中所公开的实施例描述的各示例的单元及算法步骤，本申请实施例能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。本领域技术人员可以对每个特定的应用来使用不同的方法来实现所描述的功能，但是这种实现不应认为超出本申请实施例的技术方案的范围。
本申请实施例可以根据上述方法示例对通信装置进行功能单元的划分，例如，可以对应各个功能划分各个功能单元，也可以将两个或两个以上的功能集成在一个处理单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。需要说明的是，本申请实施例中对单元的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
如图18所示，为本申请实施例提供的一种通信装置，该通信装置包括处理模块101和通信模块102。
一种可能的示例中，以通信装置为会话管理网元为例，处理模块101用于支持会话管理网元执行图5中的步骤S102，图9中的步骤S201，和/或会话管理网元需要执行的其他处理操作。通信模块102用于支持会话管理网元执行图5中的步骤S101和S103，图6中的步骤S105，图9中的步骤S202、S204和S206，图11中的步骤S301和S303，图12中的步骤S305，图15中的步骤S504-S506和S508，图17中的步骤S601，和/或会话管理网元需要执行的其他通信操作。
另一种可能的示例中，以通信装置为第一用户面网元为例，处理模块101用于支持第一用户面网元执行图5中的步骤S104，图9中的步骤S203和S207，图12中的步骤S306，图14中的步骤S405，图15中的步骤S509，图17中的步骤S602，和/或第一用户面网元需要执行的其他处理操作。通信模块102用于支持第一用户面网元执行图5中的步骤S103，图9中的步骤S202和S206，图12中的步骤S305，图14中的步骤S404，图15中的步骤S508，图17中的步骤S601，和/或第一用户面网元需要执行的其他通信操作。
另一种可能的示例中，以通信装置为第一终端设备为例，处理模块101用于支持第一终端设备执行图6中的步骤S106，图9中的步骤S205，图11中的步骤S304，图13中的步骤S403，图15中的步骤S507，和/或其他第一终端设备需要执行的其他处理操作。通信模块102用于支持第一终端设备执行图5中的步骤S101，图6中的步骤S105，图9中的步骤S204，图11中的步骤S301和S303，图13中的步骤S402，图15中的步骤S501和S506，和/或其他第一终端设备需要执行的通信操作。
另一种可能的示例中，以通信装置为应用功能网元为例，处理模块101用于支持应用功能网元执行处理操作(例如生成第三容器、生成第四容器等)。通信模块102用于支持应用功能网元执行图13中的步骤S401-S402，图14中的步骤S404，图15中的步骤S504-S505，和/或应用功能网元需要执行的其他通信操作。
可选，该通信装置还可以包括存储模块103，用于存储通信装置的程序代码和数据，数据可以包括不限于原始数据或者中间数据等。
其中，处理模块101可以是处理器或控制器，例如可以是CPU，通用处理器，专用集成电路(application specific integrated circuit，ASIC)，现场可编程逻辑门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，DSP和微处理器的组合等等。
通信模块102可以是通信接口、收发器或收发电路等，其中，该通信接口是统称，在具体实现中，该通信接口可以包括多个接口，例如可以包括：基站和终端之间的接口和/或其他接口。
存储模块103可以是存储器。
当处理模块101为处理器，通信模块102为通信接口，存储模块103为存储器时，本申请实施例所涉及的通信装置可以为图19所示。
参阅图19所示，该通信装置包括：处理器201、通信接口202、存储器203。可选的，通信装置还可以包括总线204。其中，通信接口202、处理器201以及存储器203可以通过总线204相互连接；总线204可以是外设部件互连标准(peripheral component interconnect，PCI)总线或扩展工业标准结构(extended industry standard architecture，EISA)总线等。所述总线204可以分为地址总线、数据总线、控制总线等。为便于表示，图19中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
可选的，本申请实施例还提供一种携带计算机指令的计算机程序产品，当该计算机指令在计算机上运行时，使得计算机执行上述实施例所介绍的方法。
可选的，本申请实施例还提供一种计算机可读存储介质，所述计算机可读存储介质存储计算机指令，当该计算机指令在计算机上运行时，使得计算机执行上述实施例所介绍的方法。
可选的，本申请实施例还提供一种芯片，包括：处理电路和收发管脚，处理电路和收发管脚用于实现上述实施例所介绍的方法。其中，处理电路用于执行相应方法中的处理动作，收发管脚用于执行相应方法中的接收/发送的动作。
本领域普通技术人员可以理解：在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。
所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(Digital Subscriber Line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包括一个或多个可用介质集成的服务器、数据中心等数据存 储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，数字视频光盘(Digital Video Disc，DVD))、或者半导体介质(例如固态硬盘(Solid State Disk，SSD))等。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统，装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个设备上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个功能单元独立存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用硬件加软件功能单元的形式实现。
通过以上的实施方式的描述，所属领域的技术人员可以清楚地了解到本申请可借助软件加必需的通用硬件的方式来实现，当然也可以通过硬件，但很多情况下前者是更佳的实施方式。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品存储在可读取的存储介质中，如计算机的软盘，硬盘或光盘等，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述的方法。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，在本申请揭露的技术范围内的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (36)

  1. 一种避免环路的方法，其特征在于，所述方法包括：
    会话管理网元接收来自第一终端设备的协议数据单元PDU会话建立请求消息；
    所述会话管理网元根据所述PDU会话建立请求消息，选择第一用户面网元；
    所述会话管理网元向所述第一用户面网元发送第一指示信息，所述第一指示信息用于指示激活生成树协议STP功能。
  2. 根据权利要求1所述的方法，其特征在于，所述第一指示信息用于指示激活STP功能，包括：
    所述第一指示信息用于指示针对所述第一终端设备所属群组激活STP功能。
  3. 根据权利要求2所述的方法，其特征在于，所述第一指示信息包括所述第一终端设备所属群组的标识。
  4. 根据权利要求1至3任一项所述的方法，其特征在于，所述第一指示信息还用于指示STP版本。
  5. 根据权利要求1至4任一项所述的方法，其特征在于，所述第一指示信息承载于N4接口消息中。
  6. 根据权利要求1至5任一项所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元向所述第一用户面网元发送用于配置所述第一用户面网元激活STP功能的参数。
  7. 根据权利要求6所述的方法，其特征在于，所述用于配置所述第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥媒体接入控制MAC地址、第一端口的优先级、所述第一端口的端口号、第二端口的端口号、所述第二端口的优先级、第三端口的端口号、或所述第三端口的优先级；其中，所述第一端口为所述第一用户面网元上PDU会话对应的端口，所述第二端口为所述第一用户面网元上与第二用户面网元连接的隧道对应的端口，所述第三端口为所述第一用户面网元上用于与数据网络连接的接口。
  8. 根据权利要求1至7任一项所述的方法，其特征在于，所述会话管理网元向所述第一用户面网元发送第一指示信息，包括：
    所述会话管理网元根据所述第一终端设备所属群组的标识，获取运营商策略信息；
    在所述运营商策略信息用于指示允许激活STP功能的情况下，所述会话管理网元向所述第一用户面网元发送所述第一指示信息。
  9. 根据权利要求1至7任一项所述的方法，其特征在于，所述会话管理网元向所述第一用户面网元发送第一指示信息，包括：
    所述会话管理网元根据所述第一终端设备所属群组的标识，从统一数据管理网元获取与所述第一终端设备所属群组的签约信息；
    在所述签约信息包括用于指示激活STP功能的指示信息的情况下，所述会话管理网元向所述第一用户面网元发送所述第一指示信息。
  10. 根据权利要求1至7任一项所述的方法，其特征在于，所述会话管理网元向所述第一用户面网元发送第一指示信息，包括：
    所述会话管理网元从策略控制功能网元获取所述第一终端设备的策略与计费控制 规则；
    在所述策略与计费控制规则包括用于指示激活STP功能的指示信息的情况下，所述会话管理网元向所述第一用户面网元发送所述第一指示信息。
  11. 根据权利要求1至7任一项所述的方法，其特征在于，所述会话管理网元向所述第一用户面网元发送第一指示信息，包括：
    所述会话管理网元从本地获取所述第一终端设备所属群组相关的5G本地局域网5GLAN的用户面拓扑；
    在所述5GLAN的用户面拓扑存在多个用于与数据网络连接的端口，或者所述5GLAN的用户面拓扑中存在多个用户面网元的情况下，所述会话管理网元向所述第一用户面网元发送所述第一指示信息。
  12. 根据权利要求1至11任一项所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元向所述第一终端设备发送第二指示信息，所述第二指示信息用于指示所述第一终端设备激活STP功能。
  13. 根据权利要求12所述的方法，其特征在于，所述第二指示信息还用于指示STP版本。
  14. 根据权利要求12或13所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元向所述第一终端设备发送用于配置所述第一终端设备激活STP功能的参数。
  15. 根据权利要求14所述的方法，其特征在于，所述用于配置所述第一终端设备激活STP功能的参数包括以下一项或者多项：第四端口的端口号或所述第四端口的优先级，所述第四端口为所述第一终端设备上PDU会话对应的端口。
  16. 根据权利要求12至15任一项所述的方法，其特征在于，所述会话管理网元向所述第一终端设备发送第二指示信息，包括：
    所述会话管理网元获取第一STP能力信息，所述第一STP能力信息用于指示所述第一终端设备是否支持STP功能；
    当所述第一STP能力信息用于指示所述第一终端设备支持STP功能时，所述会话管理网元向所述第一终端设备发送第二指示信息。
  17. 根据权利要求16所述的方法，其特征在于，所述PDU会话建立请求消息包括所述第一STP能力信息。
  18. 根据权利要求1至17任一项所述的方法，其特征在于，所述方法还包括：
    在所述第一用户面网元不为所述第一终端设备所属群组中的任意一个终端设备提供5GLAN服务的情况下，所述会话管理网元向所述第一用户面网元发送第三指示信息，所述第三指示信息用于指示去激活STP功能。
  19. 一种避免环路的方法，其特征在于，所述方法包括：
    第一用户面网元接收会话管理网元发送的第一指示信息，所述第一指示信息用于指示激活STP功能；
    所述第一用户面网元根据所述第一指示信息，激活STP功能。
  20. 根据权利要求19所述的方法，其特征在于，所述第一指示信息用于指示激活STP功能，包括：
    所述第一指示信息用于指示针对第一终端设备所属群组激活STP功能。
  21. 根据权利要求20所述的方法，其特征在于，所述第一指示信息包括所述第一终端设备所属群组的标识。
  22. 根据权利要求19至21任一项所述的方法，其特征在于，所述第一指示信息还用于指示STP版本。
  23. 根据权利要求19至22任一项所述的方法，其特征在于，所述第一指示信息承载于N4接口消息中。
  24. 根据权利要求19至23任一项所述的方法，其特征在于，所述方法还包括：
    所述第一用户面网元接收所述会话管理网元发送的用于配置所述第一用户面网元激活STP功能的参数。
  25. 根据权利要求24所述的方法，其特征在于，所述用于配置所述第一用户面网元激活STP功能的参数包括以下一项或者多项：桥优先级、桥MAC地址、第一端口的优先级、所述第一端口的端口号、第二端口的端口号、所述第二端口的优先级、第三端口的端口号、或所述第三端口的优先级；其中，所述第一端口为所述第一用户面网元上PDU会话对应的端口，所述第二端口为所述第一用户面网元上与第二用户面网元连接的隧道对应的端口，第三端口为所述第一用户面网元上用于与数据网络连接的接口。
  26. 根据权利要求19至25任一项所述的方法，其特征在于，所述方法还包括：
    所述第一用户面网元接收所述会话管理网元发送的第三指示信息，所述第三指示信息用于指示去激活STP功能；
    所述第一用户面网元根据所述第三指示信息，去激活STP功能。
  27. 一种避免环路的方法，其特征在于，所述方法包括：
    第一终端设备向会话管理网元发送PDU会话建立请求消息；
    所述第一终端设备接收所述会话管理网元发送的第二指示信息，所述第二指示信息用于指示所述第一终端设备激活STP功能。
  28. 根据权利要求27所述的方法，其特征在于，所述第二指示信息还用于指示STP版本。
  29. 根据权利要求27或28所述的方法，其特征在于，所述方法还包括：
    所述第一终端设备接收所述会话管理网元发送的用于配置所述第一终端设备激活STP功能时使用的参数。
  30. 根据权利要求29所述的方法，其特征在于，所述用于配置所述第一终端设备激活STP功能时使用的参数包括以下参数中的一项或者多项：第四端口的端口号、或所述第四端口的优先级，所述第四端口为第一终端设备上PDU会话对应的端口。
  31. 根据权利要求27至30任一项所述的方法，其特征在于，所述PDU会话建立请求消息包括第一STP能力信息，所述第一STP能力信息用于指示所述第一终端设备是否支持STP。
  32. 根据权利要求27至30任一项所述的方法，其特征在于，所述方法还包括：
    所述第一终端设备在注册流程中向移动管理网元发送第一STP能力信息，所述第一STP能力信息用于指示所述第一终端设备是否支持STP功能。
  33. 一种通信装置，其特征在于，所述通信装置包括用于执行权利要求1至32中任一项所涉及的方法中的各个步骤的模块。
  34. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储计算机指令，当所述计算机指令在计算机上运行时，使得所述计算机执行权利要求1至32任一项所述的方法。
  35. 一种芯片，其特征在于，所述芯片包括处理电路和收发管脚；所述处理电路用于执行权利要求1至32中任一项所涉及的方法中的处理操作，所述收发管脚用于执行权利要求1至32中任一项所涉及的方法中的通信操作。
  36. 一种包含计算机指令的计算机程序产品，其特征在于，当所述计算机指令在计算机上运行时，使得所述计算机执行权利要求1至32任一项所述的方法。
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