WO2023071318A1 - Loop detection method and apparatus - Google Patents

Abstract

A loop detection method and apparatus. The method comprises: a UPF receiving a data packet at a first port; in a MAC address table, if the number of times that port information corresponding to a source MAC address of the data packet changes within a first preset duration reaches a preset number of times, the UPF constructing a detection packet, wherein the detection packet is a broadcast data packet or a multicast data packet; and the UPF sending the detection packet to the first port, wherein the detection packet is used for detecting whether there is a loop in a network. By means of the method and apparatus in the present application, whether there is a loop in a network can be detected, such that when there is a loop in the network, a device in the loop is prevented from constantly forwarding a data packet, thereby reducing the consumption of network resources.

Description

A loop detection method and device

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number 202111268099.X and the application title "A Method and Device for Loop Detection" filed with the China Patent Office on October 29, 2021, the entire contents of which are hereby incorporated by reference In this application.

technical field

The present application relates to the field of communication technologies, and in particular to a loop detection method and device.

Background technique

In a fifth generation (5 ^th generation, 5G) network, a user plane function (user plane function, UPF) network element supports a Layer 2 broadcast flooding capability. If UPF receives unicast data packets, multicast data packets, or unicast data packets with unknown destination addresses, UPF will flood the received data packets to the entire network. If there is a loop in the network, the devices in the network will receive a large number of useless data packets in a short period of time. How to detect whether there is a loop in the network is a problem to be solved in this application.

Contents of the invention

The present application provides a loop detection method and device to detect whether there is a loop in the network.

In the first aspect, a loop detection method is provided, including: UPF receives a data packet at a first port, and the data packet is a broadcast data packet, a multicast data packet or unicast data with an unknown MAC address of the destination media access control packet; in the MAC address table, if the port information corresponding to the source MAC address of the data packet reaches a preset number of times in the first preset duration, the UPF constructs a detection packet, which is a broadcast data packet Or a multicast data packet, the MAC address table records the correspondence between the source MAC address of the data packet received by the user plane function UPF and the port information receiving the data packet; the UPF sends the detection to the first port A packet, the detection packet is used to detect whether there is a loop in the network, and the first port is a port in the UPF.

Through the above method, when UPF detects that the destination MAC address corresponding to a data packet changes frequently in a short period of time, UPF has reason to believe that the data packet is frequently forwarded in a short period of time, and there is a loop in the network. UPF can construct a detection Packets to detect whether there is a loop in the network, so as to avoid the continuous forwarding of data packets caused by loops in the network and reduce the consumption of network resources.

In one design, after the UPF sends the detection packet to the first port, it further includes: if the detection packet is received at the first port or other ports of the UPF within a second preset time period, packet, the UPF determines that there is a loop in the network; otherwise, it determines that there is no loop in the network.

Through the above method, after the UPF sends the detection packet on the first port, if it receives the detection packet at this port or other ports within a certain period of time, the UPF can clearly determine that there is a loop in the network; otherwise, the UPF It can be determined that there are no loops in the network.

In one design, it further includes: the UPF sends the detection packet to the second port, and the port information corresponding to the second port is recorded in the MAC address table, previously received through the first port There is port information corresponding to the source MAC address of the data packet, and the second port is a port in the UPF.

In one design, it also includes: when the UPF determines that there is a loop in the network, reporting a port loop event to the session management function SMF, where the port loop event includes an indication for indicating the first port Information; the UPF receives an N4 session modification message from the SMF, and the N4 session modification message indicates that the UPF stops forwarding data packets through the first port, and/or instructs the UPF to perform a loop recovery event; according to N4 session modification message, stop the data forwarding function of the first port, and/or execute the loop recovery event.

Through the above method, when the UPF determines that there is a loop in the network, it can report the port loop event to the SMF. When the SMF receives the above-mentioned port loop event, it can first alarm the OAM, and at this time, the loop in the network can be restored through manual intervention or other intelligent methods. Afterwards, the SMF sends an N4 session modification message to the UPF, which is used to instruct the UPF to stop the data forwarding function of the port, and perform loop recovery events, etc., stop the data forwarding function of the loop port, and reduce the consumption of network resources.

In one design, the port loop event includes indication information for indicating the first port, specifically: the first port is an access port, and one Ethernet protocol data unit PDU session corresponds to one interface When entering a port, the port loop event carries the identifier of the Ethernet PDU session corresponding to the first port; or, when the first port is an N6 port and one network instance corresponds to one N6 port, the port The loop event carries the identifier of the network instance corresponding to the first port; or, when the first port is an N19 port and the N19 port is an interface between UPFs, the port loop event carries The Internet Protocol IP address of the peer UPF.

In one design, the execution of the loop recovery event includes: UPF constructing a detection packet again, the detection packet is a broadcast packet or a multicast packet, and the UPF sends the detection packet to the first port; if Within the third preset time period, if the detection packet is not received at the first port or other ports of the UPF, it means that there is no loop in the network, the network returns to normal, and the loop recovery is reported to the SMF event; otherwise, continue to execute the step of sending the detection packet to the first port.

Through the above method, UPF can detect whether the loop in the network returns to normal by constructing a detection packet. If the loop in the network returns to normal, the loop recovery event can be reported to the SMF to restore the data forwarding function of the port.

In one design, the method further includes: if the loop still exists in the network within the fourth preset time period, the UPF stops the loop detection and closes the data forwarding function of the first port.

In this application, UPF can perform loop detection periodically. If the loop in the network has not been eliminated for a long time, UPF can no longer perform loop detection, and close the data of the first port where the port forms a loop. Forward function. At this time, manual intervention may be required to restore the data forwarding function of the first port, thereby reducing the energy consumption of the UPF.

In one design, after reporting the loop recovery event to the SMF, it further includes: the UPF receives an N4 session modification message from the SMF, and the N4 session modification message includes resuming the first port data packet forwarding Function indication information; according to the N4 session modification message, restore the data packet forwarding function of the first port.

In the above design, the SMF instructs the UPF to restore the forwarding function of the data packets of the first port as an example. In one design, when the UPF determines that the network is back to normal, it can actively restore the data forwarding function of the first port without waiting for an instruction from the SMF, so that the first port can return to normal as soon as possible.

In one design, when the first port is an access port, an N6 port or an N19 port, the method further includes: receiving an N4 session establishment message from the SMF, and the N4 session establishment message includes an execution The instruction information of the access port loop detection either includes the instruction information of executing the loop detection of the N6 port, or includes the instruction information of executing the loop detection of the N19 port.

Through the above method, when the SMF sends the N4 session establishment message to the UPF, it can directly instruct the UPF whether to perform loop detection on the corresponding port. When the UPF is instructed to perform the loop detection of the corresponding port, the UPF executes the method of the present application to perform the loop detection; otherwise, the UPF does not perform the loop detection. This application has better compatibility with existing schemes.

The second aspect provides a loop detection method, which is the SMF side corresponding to the first aspect above, and the beneficial effect may be as described in the first aspect above, and will not be described again. The method includes: the SMF receives from the user plane function UPF. A port loop event, the port loop event includes indication information for indicating the first port; SMF sends alarm information to OAM, the alarm information is used to indicate that there is a loop in the network, and the alarm information includes For the indication information indicating the first port, the first port is a port in the UPF.

In one design, the port loop event includes indication information of the first port, specifically: when the first port is an access port, and one Ethernet protocol data unit PDU session corresponds to one access port, the The port loop event carries the identifier of the Ethernet PDU session corresponding to the first port; or, when the first port is an N6 port and one network instance corresponds to one N6 port, the port loop event carries There is an identifier of the network instance corresponding to the first port; or, when the first port is an N19 port and the N19 port is an interface between UPFs, the port loop event carries the Internet of the peer UPF Protocol IP address.

In one design, the first port is an access port, and further includes: the SMF sends to the terminal instruction information for releasing the PDU session corresponding to the first port, and the instruction information carries information for releasing the Ethernet PUD session The cause is the indication information of network looping; or, the SMF sends an N4 session modification message to the UPF, and the N4 session modification message instructs the UPF to stop forwarding data packets through the access port, and/or instructs the UPF to Perform a loop recovery event.

In one design, the first port is an N6 port or an N19 port, and further includes: the SMF sends an N4 session modification message to the UPF, and the N4 session modification message instructs the UPF to stop passing through the N6 port or the N19 port. Port forwarding packets, and/or instructing the UPF to perform a loop recovery event.

In one design, it also includes: the SMF receives the loop recovery event from the UPF; the SMF sends a recovery alarm to the OAM, and the recovery alarm is used to indicate that there is no loop in the network and the network returns to normal; The UPF sends an N4 session modification message, where the N4 session modification message includes indication information for restoring the data packet forwarding function of the first port.

In one design, when the first port is an access port, N6 port or N19 port, the method further includes: the SMF sends an N4 session establishment message to the UPF, and the N4 session establishment message includes an execution interface The instruction information of the loop detection on the ingress port, or the instruction information of executing the loop detection of the N6 port, or the instruction information of executing the loop detection of the N19 port.

In the third aspect, there is provided a communication device, which includes a one-to-one unit or module for performing the methods/operations/steps/actions described in the first aspect above, and the unit or module can be a hardware circuit or software, It can also be implemented by combining hardware circuits with software.

According to a fourth aspect, a communication device is provided, and the device includes a processor and a memory. Wherein, the memory is used to store computer programs or instructions, and the processor is coupled to the memory; when the processor executes the computer programs or instructions, the device is made to execute the method of the first aspect above.

According to the fifth aspect, a communication device is provided, which includes a one-to-one unit or module for performing the methods/operations/steps/actions described in the second aspect. The unit or module can be a hardware circuit, software, or It can be implemented by combining hardware circuits with software.

According to a sixth aspect, a communication device is provided, and the device includes a processor and a memory. Wherein, the memory is used to store computer programs or instructions, and the processor is coupled to the memory; when the processor executes the computer programs or instructions, the device is made to execute the method of the second aspect above.

According to the seventh aspect, a computer-readable storage medium is provided, the computer-readable storage medium stores computer programs or instructions, and when the computer programs or instructions are executed by the device, the device executes the above-mentioned first aspect or the second aspect Methods.

In an eighth aspect, a computer program product is provided, the computer program product includes a computer program or an instruction, and when the computer program or instruction is executed by a device, the device executes the method of the first aspect or the second aspect above.

A ninth aspect provides a communication system, including the above-mentioned third aspect or the fourth aspect, and the device of the fifth aspect or the sixth aspect.

Description of drawings

Figure 1 is a schematic diagram of the network architecture provided by the present application;

Fig. 2 is the schematic diagram of the PDU connection that this application provides;

Fig. 3 is the schematic diagram of the Ethernet PDU conversation that the application provides;

Fig. 4 is the exchange schematic diagram of the Ethernet PDU session provided by the present application;

FIG. 5 is a schematic diagram of a UPF port provided by the present application;

6 to 11 are schematic diagrams of network looping provided by the present application;

FIG. 12 is a flow chart of the loop detection method provided by the present application;

FIG. 13 is a schematic diagram of an access port loop provided by the present application;

Fig. 14 is the schematic diagram of the N6 port loop provided by the present application;

Figure 15 is a schematic diagram of the N19 port loop provided by the present application;

FIG. 16 and FIG. 17 are schematic diagrams of communication devices provided by the present application.

Detailed ways

The technical solutions of the present application are described below in conjunction with the accompanying drawings of the present application.

As shown in FIG. 1 , a network architecture applicable to this application is provided, including an access network, a core network, and terminals.

Wherein, the access network is used to implement functions related to wireless access, and the access network device is a device that provides access for the terminal. The access network device may also be called a radio access network (radio access network, RAN) device. The RAN device is mainly responsible for radio resource management, quality of service (QoS) management, data compression and security processing on the air interface side. The RAN equipment may include various forms of base stations. For example, a macro base station, a micro base station (small cell), a relay station or an access point, etc. RAN equipment includes but is not limited to: the next-generation base station (generation nodeB, gNB) in the fifth generation (5 ^th generation, 5G), the evolved node B (evolved node B, eNB), the radio network controller (radio network controller, RNC), node B (node B, NB), base station controller (base station controller, BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved nodeB, or home node B, HNB) , baseband unit (baseband unit, BBU), transceiver point (transmitting and receiving point, TRP), transmitting point (transmitting point, TP), mobile switching center, etc. The RAN device may also be a wireless controller, a centralized unit (centralized unit, CU), and/or a distributed unit (distributed unit, DU) in a cloud radio access network (cloud radio access network, CRAN) scenario, or the RAN device may For relay stations, access points, vehicle-mounted equipment, terminals, wearable devices, and access network equipment in the future ^sixth generation (6th generation, 6G) network or future evolution of public land mobile network (PLMN) ) access network equipment in the network, etc. For ease of description, a base station is used as an example of a RAN device for description below.

The core network equipment may include one or more of the following network elements: access and mobility management function (access and mobility management function, AMF), session management function (session management function, SMF), user plane function (user plane function, UPF), policy control function (policy control function, PCF), application function (application function, AF), unified data management (unified data management, UDM), authentication server function (authentication server function, AUSF), network slice selection function ( network slice selection function, NSSF).

AMF: Mainly responsible for mobility management in the mobile network, such as user location update, user registration network, user switching, etc. SMF: It is mainly responsible for session management in mobile networks, such as session establishment, modification, and release. Specific functions such as assigning Internet protocol (internet protocol, IP) addresses to users, selecting UPF that provides message forwarding functions, etc. UPF: It is mainly responsible for the forwarding and receiving of user data. In downlink transmission, UPF can receive user data from the data network (DN) and transmit it to the terminal through the access network device; in uplink transmission, UPF can receive user data from the terminal through the access network device and forward it to the DN the User Data. Optionally, the transmission resources and scheduling functions for providing services to terminals in the UPF can be managed and controlled by the SMF. PCF: It mainly supports the provision of a unified policy framework to control network behavior, provides policy rules to the network functions of the control layer, and is responsible for obtaining user subscription information related to policy decisions. AF: It mainly supports interaction with the 3GPP core network to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side. UDM is mainly used to generate authentication credentials, user identification processing (such as storing and managing user permanent identities, etc.), access authorization control, and contract data management. AUSF is mainly used to perform authentication when the terminal accesses the network, including receiving the authentication request sent by the security anchor function (SEAF), selecting the authentication method, and submitting to the authentication repository and processing function (authentication repository and processing function, ARPF) request authentication vector, etc. NSSF is mainly used to select network slice instances for terminals, determine allowed network slice selection assistance information (network slice selection assistance information, NSSAI), configure NSSAI, and determine the AMF set of service terminals.

It should be noted that, in different communication systems, the above network elements in the core network may have different names. In the above-mentioned schematic diagram shown in FIG. 1 , the fifth generation mobile communication system is taken as an example for illustration, which is not intended to limit the present application. Further, the network elements of the core network in FIG. 1 are only for schematic illustration, and are not intended to limit the present application. For example, in the network architecture shown in Figure 1, the core network elements may also include: network exposure function (network exposure function, NEF), network storage function (network repository function, NRF), or service control point (service control point) , one or more network elements in SCP), etc.

A terminal may also be called terminal equipment, user equipment (user equipment, UE), mobile station, mobile terminal, and so on. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things ( Internet of things, IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, etc. Terminals can be mobile phones, tablet computers, computers with wireless transceiver functions, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. This application does not limit the specific technology and specific equipment form adopted by the terminal. For ease of description, a UE or a personal computer (personal computer, PC) is used as an example of a terminal for description below.

Optionally, in the network architecture shown in FIG. 1 , it may further include: DN. The DN may be a service network that provides data service for users. For example, the DN may be an IP multimedia service (IP multi-media service) network or the Internet (internet). Wherein, the terminal can establish a protocol data unit (protocol data unit, PDU) session from the terminal to the DN to access the DN.

It should be noted that in this application, the functions of the base station may also be performed by modules (such as chips) in the base station, or may be performed by a control subsystem including the functions of the base station. The control subsystem including base station functions here may be the control center in the above application scenarios such as smart grid, industrial control, intelligent transportation, and smart city. The functions of the terminal may be performed by a module (such as a chip or a modem) in the terminal, or may be performed by a device including the terminal function. The functions of the core network element (such as UPF or SMF, etc.) can also be performed by modules (such as chips) in the core network element, or can be performed by the control subsystem including the core network element.

In 5G network, data exchange service is provided for UE and DN network, which is called PDU connection service. The UE obtains the PDU connection service by initiating a PDU session establishment request to the mobile network. The network side provides the PDU connection service by maintaining the PDU session for the UE. As shown in Figure 2, the bold dashed line indicates the service data exchange path between the UE and the DN network. This path is the data service path of the UE in the mobile network, which may be referred to as the data plane path for short. The bold solid line indicates the signaling exchange path between the UE and the DN, which is the signaling service data of the UE in the mobile network, which may be referred to as signaling plane signaling for short. In order to realize the data exchange between the UE and the DN network, the UE needs to use the PDU connection service provided by the mobile network to establish a PDU session based on the data network name (DNN). The establishment of a PDU session includes two basic processes: the UE registers with the mobile network to access the network, and the UE requests the network to establish a PDU session. These two processes belong to the signaling plane interaction process between the UE and the mobile network. The network elements involved in the bold solid line in Figure 2 are the main network elements involved in the establishment of the PDU session.

Wherein, the general user registration and network access process may include: the UE sends a registration request to the AMF through the base station, and the AMF obtains subscription data from a specific UDM according to the user identifier. In addition, the AMF can also initiate a user policy control establishment request (UE policy control cteate) and an access management policy control establishment request (AM policy control creat) to the PCF, which are used to obtain UE policies and access control policies respectively. The PCF returns the access control policy to the AMF during this process. The AMF responds to the UE's registration request, and sends relevant policy information to the UE, and the UE completes network registration and camping. The AMF on the network side maintains the registration information of the UE and performs mobility management on the UE.

After the UE completes registration and access to the network, it can initiate the establishment of a PDU session to obtain the PDU connection service of the network. The general PDU session establishment process may include: the UE sends a PDU session establishment request to the AMF through the base station, and the AMF selects the SMF to provide session services for the UE, saves the correspondence between the SMF and the PDU session, and sends the session establishment request to the SMF. Select the corresponding UPF and establish a user plane transmission path, and assign an IP address to it. During this process, the SMF will also initiate a policy control session establishment request to the PCF for establishing a policy control session between the SMF and the PCF. During the establishment of the policy control session, the SMF will save the correspondence between the policy control session and the PDU session .

Currently, three types of PDU sessions are supported in the 5G network: IP-type PDU sessions (referred to as IP sessions for short), including IPV4 sessions and IPV6 sessions, and Ethernet-type PDU sessions (referred to as Ethernet sessions for short). As shown in FIG. 3 , an architecture diagram of an Ethernet PDU session is provided, including: a terminal side, a 3GPP channel, and a DN side. Ethernet is used on the end side, and PC1 is a PC in the Ethernet. The customer premise equipment (CPE) mainly plays the role of bridging. The left port of the CPE is connected to the Ethernet, and the right port is connected to the 3GPP network. Taking PC1 to transmit data to PC2 as an example, when the CPE receives the data from PC1, it transmits the data to the 3GPP network. The base station and UPF of the 3GPP network forward the data to the corresponding local switch (local switch, LSW) on the DN side according to the destination address of the data, and the LSW forwards the data to PC2. Optionally, the foregoing FIG. 3 is only a schematic diagram, and is not intended to limit the present application. For example, as shown in FIG. 4, a layer 2 switch (layer 2 switch, L2SW) may also be set between the PC1 and the CPE.

In this application, as shown in Figure 4, UPF supports local exchange (the local exchange refers to the data exchange of different PC1 under the same UPF, for example, PC1 and PC2 exchange), inter-network exchange (the inter-network exchange Refers to the exchange between the end-side terminal and the DN-side terminal, such as the exchange between PC1 and PC4) and cross-UPF exchange (the cross-UPF exchange refers to the data exchange between PCs under different UPFs, such as the exchange between PC2 and PC3). It can be understood that the above exchange refers to data transmission between different PCs.

In this application, UPF supports layer two broadcast flooding capability, and said layer two refers to the media access control (media access control, MAC) layer, that is, if UPF receives broadcast, multicast or data packets with unknown destination MAC address, Then, except the source end, UPF needs to send the data packet to all terminals in the entire local area network (local area network, LAN). In an example, the data packet with an unknown destination MAC refers to a data packet whose destination MAC address has not been learned by the UPF, that is, the corresponding relationship between the destination MAC address and the port is not recorded in the MAC address table. For example, as shown in Figure 4, if PC1, PC2, PC3, and PC4 belong to the same LAN, then when UPF1 receives a data packet sent by PC1 with destination MAC addresses all F, UPF1 needs to send the data packet to PC2, PC3 and PC4.

For example, as shown in Figure 5, there are various interfaces in the UPF. In this application, various interfaces in FIG. 5 can be abstracted into various ports. For example, the N3/N9 interface is the access port, and the UPF is connected to the CPE through the access port. One Ethernet PDU session corresponds to one access port; the N6 interface is the N6 port, and the UPF is connected to the DN through the N6 port. A network instance (network instance ) corresponds to an N6 port; the N19 interface is an N19 port, and the UPF is connected to other UPFs through the N19 port, and a group session + a peer UPF corresponds to an N19 port. Optionally, all the above ports may belong to the same network instance.

In one design, if UPF1 receives a data packet from a certain port, the port can be an access port, N6 port or N19 port, etc., it can first learn the correspondence between the source MAC address of the data packet and the receiving port, and The learned corresponding relationship is stored in the MAC address table, and then the data packet is forwarded according to the destination MAC address of the data packet. For example, UPF1 may query the port corresponding to the destination MAC address of the data packet in the MAC address table. For example, if the port found in the MAC address is the N19 port, the UPF can send the data packet through the N19 port.

In this application, when UPF receives a multicast packet, a broadcast packet, or a unicast packet with an unknown destination MAC address, it will flood to all access ports, N6 port and N19 port except the source port. If there is a loop in the network, the devices in the network will receive a large number of useless duplicate packets in a short time, wasting network resources. It should be noted that in the above description of this application, UPF is used as an example to describe flooding. In essence, all devices or ports in the Ethernet session receive broadcast, multicast or unicast with unknown destination MAC address. Flooding operation will be performed when the data packet is received.

In this application, a networking scenario in which a network forms a loop is described as an example.

Scenario 1: Access port loop

As shown in Figure 6, LSW1, CPE1, CPE2, and UPF form a loop. If device 1 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, LSW1 forwards the data packet to CPE1 and CPE2 when receiving the data packet. CPE1 and CPE2 forward the data packet to the UPF. When the UPF receives the data packet of CPE1, it forwards the data packet to device 3, CPE2 and device 2. CPE2 continues to forward the data packet to LSW1, which causes device 2 and device 3 to receive a large number of repeated useless data packets within a short period of time.

Scenario 2: Access port + N19 port loop

As shown in Figure 7, UPF1, UPF2, CPE2, LSW, and CPE1 form a loop. If device 1 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, the data packet will be continuously forwarded in the loop and flooded to other places in the network. A large number of repeated useless data packets will be received within a period of time.

Scenario 3: End-to-side self-organizing network loop

As shown in Figure 8, a loop is formed between LSW1 and CPE1. If device 1 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, the data packet will be continuously forwarded in the loop and flooded to other places in the network, and device 2 and device 3 will In a short period of time, a large number of repeated useless data packets are received.

Scenario 4: Self-loop on the DN side

As shown in Figure 9, the DN SW and VXLAN SW on the DN side form a loop. If device 3 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, the data packet will be continuously forwarded in the loop and flooded to other places in the network. A large number of repeated useless data packets will be received.

Scenario 5: Loop between N6 port and N19 port

As shown in Figure 10, a loop is formed between UPF1, VXLAN SW1, DNS SW, VLAN SW2, and UPF2. If device 3 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, the data packet will be continuously forwarded in the loop and flooded to other places in the network. A large number of repeated useless packets will be received within a period of time.

Scenario 6: N3 port and N6 port loop

As shown in Figure 11, a loop is formed between UPF, VXLAN SW, and CPE2. If device 1 initiates a multicast packet, broadcast packet, or unicast packet with an unknown destination MAC address, the data packet will be continuously forwarded in the loop and flooded to other places in the network, and device 2 will Received a lot of useless packets.

This application provides a loop detection method, which can be used to detect whether there is a loop in the network, and if there is a loop in the network, the relevant loop-breaking operations can be performed in time, thereby preventing the device from receiving a large number of repeated useless loops in a short period of time. packets, reducing the waste of network resources. As shown in Figure 12, the method at least includes the following steps:

Step 1201: The UPF receives a data packet at the first port, and the data packet is a broadcast data packet, a multicast data packet or a unicast data packet with an unknown destination MAC address.

Wherein, the above-mentioned first port may be an access port (that is, an N3/N9 port), an N6 port or an N19 port.

Step 1202: In the MAC address table, if the port corresponding to the source MAC address of the data packet has changed the number of times within the first preset time length to a preset number of times, the UPF constructs a detection packet, and the detection packet is a broadcast data packet or multicast packets.

In this application, the MAC address table records the correspondence between the source MAC address of the data packet received by the UPF and the port information that received the data. When the UPF receives a data packet, it learns the source MAC address of the data packet, and records the corresponding relationship between the source MAC address of the data packet and the receiving port in the MAC address table. When subsequently receiving a data packet whose destination MAC address is the above-mentioned source MAC address, the data packet is forwarded through a corresponding port. For example, the UPF receives data packet 1 through port 1, and the source MAC address of the data packet 1 is MAC address A. The UPF can learn the MAC address A, and record the correspondence between the MAC address A and port 1. Subsequently, when the UPF receives the data packet 2, if the destination MAC address of the data packet 2 is MAC address A, the UPF may send the data packet 2 to the port 1. In this application, when the UPF receives a data packet, if in the MAC address table, the port corresponding to the source MAC address of the data packet reaches the preset number of times within the first preset duration, the Data packets may be forwarded between different devices. At this time, there is reason to suspect that there is a loop in the network. UPF can construct a detection packet to detect whether there is a loop in the network. If the UPF receives the detection packet at the sending port of the detection packet or other ports within the second preset time period, the UPF determines that there is a loop in the network; otherwise, the UPF determines that there is no loop in the network.

Step 1203: The UPF sends the detection packet to the first port, and the detection packet is used to detect whether there is a loop in the network.

It can be seen from the description of the above step 1201 that the above-mentioned first port is a port for receiving the data packet. In addition to sending the detection packet to the above-mentioned first port, the UPF may also send the detection packet to the second port, and the port information corresponding to the second port is recorded in the MAC address table, previously and through the There is port information corresponding to the source MAC address of the data packet received by the first port. Assuming that the UPF receives a data packet at the first port, the data packet may be called a target data packet. If UPF finds that the port information corresponding to the source MAC address of the target data packet changes frequently through the MAC address table, UPF may suspect that there is a loop in the network, causing the data packet to be forwarded between different devices, making UPF The target packet is repeatedly received within the time. At this time, UPF can construct a detection packet to detect whether there is a loop in the network. The UPF may send the detection packet through the first port receiving the target data packet. Optionally, the UPF may also query the MAC address table for a port corresponding to the source MAC address of the target data packet recorded in the MAC address table, which may be referred to as a second port. In addition to the first port, the UPF may also send the detection packet through the second port. If the UPF receives the detection packet again through the port that sent the detection packet or other ports within the second preset time period, the UPF may determine that there is a loop in the network. Otherwise, it is determined that there are no loops in the network.

In this application, if the UPF determines that there is indeed a loop in the network, it may report a port loop event to the SMF network element, and the port loop event includes indication information for indicating the first port. When the SMF receives the above-mentioned port loop event, it can send alarm information to the operation management and maintenance system (operation administration and maintenance, OAM), the alarm information is used to indicate that there is a loop in the network, and the alarm information includes Indication information indicating the first port, where the first port belongs to the network. Optionally, when receiving the above alarm, the OAM may remove the loop in the network manually or in other ways.

In an example, if the above-mentioned first port is an access port, that is, the N3/N9 port, the UPF reports the access port loop event to the SMF. Since one PDU session corresponds to one access port, the access port loop event may carry the identifier of the Ethernet PDU session corresponding to the first port. When the SMF receives the above access port loop event, it can perform at least one of the following operations:

1. The SMF actively releases the Ethernet PDU session corresponding to the access port, and sends instruction information for releasing the Ethernet PDU session corresponding to the access port to the UE. For example, the SMF may send a non-access stratum (non-access stratum, NAS) message for releasing the Ethernet PDU session to the UE, where the NAS message carries the reason for releasing the Ethernet PDU session that the network is looped. When the UE receives the NAS message, it releases the Ethernet PDU session, and the UE cannot establish the Ethernet PDU session again in a short time, so as to prevent the access port loop event from being triggered again.

2. The SMF sends an N4 session modification message to the UPF, in which the N4 session modification message instructs the UPF to stop forwarding data packets through the access port, and/or instructs the UPF to execute the access port loop recovery event.

In an example, if the first port is an N6 port, the UPF reports the N6 port loop event to the SMF. One network implementation corresponds to one N6 port, and the above-mentioned N6 port loop event carries the identifier of the network instance corresponding to the N6 port. When the SMF receives the alarm of the above-mentioned N6 port loop event, the following operations can be performed: the SMF sends an N4 session modification message to the UPF, and the N4 session message instructs the UPF to stop forwarding data packets through the N6 port, and/or indicates the The above UPF executes the N6 port loop recovery event, etc. Optionally, the SMF may set all relevant Ethernet PUD session settings under the network implementation corresponding to the N6 port to stop forwarding data packets to the N6 port.

In an example, if the first port is the N19 port, the UPF reports the N19 port loop event to the SMF. Port N19 is the interface between UPFs. Optionally, each N19 port under each UPF corresponds to each peer UPF under a 5G LAN group. The above-mentioned N19 port loop event carries the IP address of the peer UPF. When the SMF receives the N19 port loop event, it can send an N4 session modification message to the UPF, the N4 session modification message carries the UPF to stop forwarding data packets through the N19 port, and/or instruct the UPF to perform N19 loop recovery events etc.

It should be noted that in the above description, the SMF instructs the UPF to stop forwarding data packets through the first port, or instructs the UPF to execute the loop recovery event as an example. It can be understood that when the UPF determines that there is a loop in the current network, it can stop forwarding data packets through the port by itself, and/or perform loop recovery events, etc., without waiting for an instruction from the SMF.

In this application, the process of the UPF executing the loop recovery event may include: the UPF forms a detection packet, and the detection packet may also be a broadcast packet or a multicast packet. The UPF sends the detection packet to the first port. If within the third preset time length, the first port or other ports of the UPF do not receive the detection packet, it means that there is no loop in the network, the network returns to normal, and the loop recovery event is reported to the SMF; otherwise, Continue the above process, construct a detection packet, and send the detection packet to the first port.

In an example, the UPF may start a timer, periodically form a detection packet, and send the detection packet from the first port to perform loop detection. For example, the timing duration of the timer may be 2 minutes, and the UPF may perform loop detection every 2 minutes. The process of each loop detection may include: the UPF constructs a detection packet, and sends the detection packet through the first port. If within the preset duration, of course, the preset duration should be shorter than the loop detection period mentioned above, and the UPF receives the detection packet at the first port or other ports, it means that there is still a loop in the network, and the loop continues detection. For a certain loop detection, if the detection packet is not received at the first port or other ports within a preset period of time after sending the detection packet, it means that the loop is back to normal, and the loop recovery event is reported to the SMF. Optionally, when the SMF receives the loop recovery event reported by the UPF, it may send a recovery alarm to the OAM, the recovery alarm is used to indicate that there is no loop in the network and the network returns to normal. The SMF may send an N4 session modification message to the UPF, where the N4 session modification message includes indication information for restoring the data forwarding function of the first port. Optionally, the N4 session modification message may carry a packet detection rule (packet detection rule, PDR), a forwarding action rule (forwarding action rule, FAR), etc. The UPF forwards data according to the requirements of the newly indicated PDR and FAR.

Referring to the above description, it can be seen that the UPF starts a timer to perform loop detection at regular intervals. If the loop in the network still exists after a certain period of time, such as the fourth preset period of time, the UPF may stop loop detection and close the data forwarding function of the first port. Optionally, in this case, manual intervention may be required to restore the data forwarding function of the first port, such as manually triggering a CPE reset, or issuing a local operation maintenance (OM) to restore the data forwarding function, etc.

Optionally, before the above step 1201, it may also include: the SMF sends an N4 session establishment message to the UPF, the above-mentioned first port is an access port, and the N4 session establishment message includes instruction information for performing loop detection on the access port; Or, the first port is an N6 port, and the above-mentioned N4 session establishment message includes an instruction to perform loop detection on the N6 port; or, the first port is an N19 port, and the above-mentioned N4 session establishment message includes an instruction to perform loop detection on the N19 port information.

In the Layer 2 switching mechanism, multicast packets, broadcast packets, or unicast packets with unknown destination addresses are forwarded in a flooding manner. If there is a loop in the network, data packets will be continuously forwarded in the network, consuming network resources. In this application, UPF can perform loop detection on each interface defined in 3GPP, and after an alarm, can detect whether the loop in the network is recovered again to ensure the stable operation of the network.

In an example, the present application is described by taking the loop detection and breaking of the access port as an example. As shown in Figure 13, UPF receives a data packet through the access port, that is, N3/N9, and the source MAC address of the data packet changes frequently in a short period of time, at least including the following process:

1. When the CPE establishes an Ethernet PDU session, the SMF requests the UPF to perform an access port loop detection event in the N4 session establishment message.

2. When UPF receives an uplink data packet from the access port, when recording the source MAC address of the uplink data packet in the MAC address table, if the source MAC address of the data packet changes frequently in a short period of time, UPF Construct a detection packet and deliver it from the access port for loop detection. If the UPF receives the detection packet on the access port or other ports within a short period of time, the UPF considers that the network connected to the access port forms a loop; the UPF reports the access port loop event to the SMF.

3. When the SMF receives the above-mentioned access port loop event, it first sends an alarm to the OAM, and then can perform any of the following operations. Optionally, the specific operations to be performed can be determined by the local configuration of the SMF:

A. The SMF actively releases the Ethernet PDU session corresponding to the access port, and sends NAS signaling to the UE to release the Ethernet PDU session. The NAS signaling includes that the reason for releasing the Ethernet PDU session is network looping. Optionally, the UE cannot establish the Ethernet PDU session again within a short period of time, so as to avoid triggering the access port loop event again.

B. The SMF sends an N4 session modification message to the UPF, and the N4 session modification message requires the UPF to stop forwarding data packets, and requires the UPF to perform an access port loop recovery event.

4. When the UPF receives the N4 session modification message in the above-mentioned scheme B, it starts a timer, constructs a detection packet regularly, and sends it from the access port to perform loop detection.

If the UPF does not receive the detection packet from the access port or other ports within a short period of time, the UPF reports the access port loop recovery event to the SMF. Or, if the UPF receives the detection packet again at the above-mentioned access port or other ports within a short event, the UPF continues to perform detection according to the period of the above-mentioned timer. If the network does not recover for a long time, the UPF will terminate the data forwarding capability of the access port. At this time, manual intervention may be required to restore the data forwarding capability of the access port.

5. When the SMF receives the loop recovery event reported by the UPF, it first reports the recovery alarm to the OAM, and then sends an N4 session modification message to the UPF, which contains a request for the UPF to restore the data forwarding function of the access port. Instructions.

In an example, the present application is described by taking the loop detection and breaking of the N6 port as an example. As shown in Figure 14, the UPF receives a data packet through the N6 port. According to the records in the MAC address table, the source MAC address of the data packet changes frequently in a short period of time, at least including the following process:

1. When CPE establishes an Ethernet PDU session, SMF requires UPF to perform N6 port loop detection event in the N4 session establishment message, and requires UPF to stop forwarding data to N6 port when a loop event occurs, until the N6 port loop is restored .

2. When the UPF receives a downlink data packet from the N6 interface, if the source MAC address of the recorded data packet is found to change frequently in a short period of time, the UPF can form a detection packet and send it from the N6 port. Loop detection. If within a short period of time, UPF receives the detection packet from the N6 port or other ports, the UPF considers that the network connected to the N6 port forms a loop, and reports the N6 port loop event to the SMF, which carries the network information corresponding to the N6 port. instance. UPF automatically stops forwarding packets to N6 port.

3. When the SMF receives the above-mentioned N6 port loop event, it sends an alarm to the OAM. Optionally, the SMF may set all relevant Ethernet PDU sessions under the network instance corresponding to the N6 port to stop forwarding data packets to the N6 port.

4. The UPF starts a timer, constructs a detection packet regularly, and sends it from the N6 port for loop detection.

If the UPF does not receive the detection packet from the N6 port or other ports within a short period of time, the UPF reports the N6 port loop recovery event to the SMF. Optionally, the SMF may further perform corresponding operations, such as reporting a recovery alarm to the OAM.

If the UPF receives the detection packet from the N6 port or other ports within a short period of time, the UPF will continue to perform loop detection periodically according to the timing of the timer. If the loop in the network does not recover for a long time, UPF will terminate the data forwarding function of the N6 port, and manual intervention may be required to restore the data forwarding function of the N6 port.

In an example, the loop detection and breaking of the N19 port is taken as an example. As shown in Figure 15, UPF1 receives a data packet through the N19 port. The source MAC address of the data packet, in the record in the MAC address table, changes frequently in a short period of time, and at least includes the following process:

1. When the SMF finds that a forwarding channel needs to be established between different UPFs, the SMF requests the UPF to perform the N19 port loop detection event in the N4 session establishment message.

2. When UPF receives a data packet at the N19 port and records the MAC address, if it finds that the source MAC address of the data packet changes frequently in a short period of time, the UPF constructs a detection packet and sends it from the N19 port for loop detection. If within a short period of time, UPF receives the detection packet on the N19 port or other ports, UPF considers that the network connected to the N19 port forms a loop; UPF reports the N19 port loop event to the SMF, and the N19 port loop event carries There is IP correspondence of the opposite side UPF. For example, the IP address of UPF2 in Figure 15.

3. When the SMF receives the N19 port loop event, it first reports to the OAM, and then sends the N4 session modification message to the UPF. The N4 session modification message may include instructions to request the UPF to stop forwarding data packets to UPF2, and request the UPF to execute Instructions for loop recovery events on the N19 port.

4. When the UPF receives the above-mentioned N4 session modification message, it first starts a timer, and regularly constructs a detection packet to be sent from the N19 port for loop detection.

If the UPF does not receive the detection packet from the local N19 port or other ports within a short period of time, the UPF reports the N19 port loop recovery event to the SMF, and the N19 port loop recovery event carries the IP address of the peer UPF. If the UPF receives the detection packet at the N19 port or other ports within a short period of time, the UPF will continue to construct the detection packet for loop detection according to the timing period of the timer. If the network has not returned to normal for a long time and there is a loop in the network, the UPF terminates the data forwarding function of the N19 port, and manual intervention is required to restore the data forwarding function of the N19 port.

5. When the SMF receives the N19 port loop recovery event, it first sends a recovery alarm to the OAM, and sends an N4 session modification message to the UPF, requesting the UPF to resume forwarding data packets to UPF2. The UPF forwards the data packet according to the requirements of the new PDR and FRA carried in the N4 session modification message.

It can be understood that, in order to realize the functions in the foregoing method embodiments, the UPF and the SMF include hardware structures and/or software modules corresponding to each function. Those skilled in the art should easily realize that the present application can be implemented in the form of hardware or a combination of hardware and computer software with reference to the units and method steps of each example described in the embodiments disclosed in the present application. Whether a certain function is executed by hardware or computer software drives the hardware depends on the specific application scenario and design constraints of the technical solution.

FIG. 16 and FIG. 17 are schematic structural diagrams of possible communication devices provided in this application. These communication devices can be used to implement the functions of the UPF or SMF in the above method embodiments, and therefore can also achieve the beneficial effects of the above method embodiments. In this application, the communication device may be a UPF or an SMF as shown in FIG. 1 , and may also be a module (such as a chip) applied to the UPF or the SMF.

As shown in FIG. 16 , a communication device 1600 includes a processing unit 1610 and a transceiver unit 1620 . The communication device 1600 is configured to implement the functions of the UPF or the SMF in the foregoing method embodiments.

When the communication device 1600 is used to realize the function of UPF in the above method embodiment: the transceiver unit 1620 is used to receive a data packet at the first port, and the data packet is a broadcast data packet, a multicast data packet or an unknown destination MAC address A unicast data packet; a processing unit 1610 configured to construct a detection packet in the MAC address table if the port information corresponding to the source MAC address of the data packet reaches a preset number of times within the first preset duration , the detection packet is a broadcast data packet or a multicast data packet, and the MAC address table records the correspondence between the source MAC address of the data packet received by the UPF network element and the port information receiving the data packet; the transceiver unit 1620, It is also used to send the detection packet to the first port, where the detection packet is used to detect whether there is a loop in the network.

When the communication device 1600 is used to implement the SMF function in the above method embodiment: the transceiver unit 1620 is used to receive a port loop event from a UPF network element, and the port loop event includes an indication for indicating the first port information; the processing unit 1610 is configured to generate alarm information; the transceiver unit 1620 is also configured to: send alarm information to OAM, the alarm information is used to indicate that there is a loop in the network, and the alarm information includes the Indication information of the first port, where the first port is a port in the UPF.

A more detailed description about the processing unit 1610 and the transceiver unit 1620 can be obtained according to the relevant description in the above method embodiment, and details are not repeated here.

As shown in FIG. 17 , a communication device 1700 includes a processor 1710 and an interface circuit 1720 . The processor 1710 and the interface circuit 1720 are coupled to each other. It can be understood that the interface circuit 1720 may be a transceiver or an input-output interface. Optionally, the communication device 1700 may further include a memory 1730 for storing instructions executed by the processor 1710 or storing input data required by the processor 1710 to execute the instructions or storing data generated by the processor 1710 after executing the instructions.

When the communication device 1700 is used to implement the methods in the above method embodiments, the processor 1710 is used to implement the functions of the processing unit 1610 , and the interface circuit 1720 is used to implement the functions of the transceiver unit 1620 .

When the above communication device is a module applied to UPF, the UPF module realizes the function of UPF in the above method embodiment. The UPF module receives information from other modules in the UPF (such as a radio frequency module or an antenna), and the information is sent to the UPF by the SMF; or, the UPF module sends information to other modules in the UPF (such as a radio frequency module or an antenna). The information is sent by the terminal to the UPF. The UPF module here can be a UPF chip or other modules.

When the above-mentioned communication device is a module applied to the SMF, the SMF module realizes the function of the SMF in the above-mentioned method embodiment. The SMF module receives information from other modules in the SMF (such as a radio frequency module or an antenna), and the information is sent to the SMF by the UPF; or, the SMF module sends information to other modules in the SMF (such as a radio frequency module or an antenna). Information is sent by SMF to UPF. The SMF module here can be an SMF chip or other modules.

It can be understood that the processor in this application can be a central processing unit (central processing unit, CPU), and can also be other general processors, digital signal processors (digital signal processor, DSP), application specific integrated circuits (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. A general-purpose processor can be a microprocessor, or any conventional processor.

The method steps in the embodiments of the present application may be implemented by means of hardware, or may be implemented by means of a processor executing software instructions. Software instructions can be composed of corresponding software modules, and software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only Memory, registers, hard disk, removable hard disk, CD-ROM or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be a component of the processor. The processor and storage medium can be located in the ASIC. In addition, the ASIC can be located in the base station or the terminal. Certainly, the processor and the storage medium may also exist in the base station or the terminal as discrete components.

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

In each embodiment of the present application, if there is no special explanation and logical conflict, the terms and/or descriptions between different embodiments are consistent and can be referred to each other, and the technical features in different embodiments are based on their inherent Logical relationships can be combined to form new embodiments.

In this application, "at least one" means one or more, and "multiple" means two or more. "And/or" describes the association relationship of associated objects, indicating that there can be three types of relationships, for example, A and/or B, which can mean: A exists alone, A and B exist at the same time, and B exists alone, where A, B can be singular or plural. In the text description of this application, the character "/" generally indicates that the contextual objects are an "or" relationship; in the formulas of this application, the character "/" indicates that the contextual objects are a "division" Relationship. "Including at least one of A, B and C" may mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B and C.

It can be understood that the various numbers involved in the embodiments of the present application are only for convenience of description, and are not used to limit the scope of the embodiments of the present application. The size of the serial numbers of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its functions and internal logic.

Claims (21)

1. A loop detection method, characterized in that, comprising:

   A data packet is received at the first port, and the data packet is a broadcast data packet, a multicast data packet, or a unicast data packet with an unknown destination MAC address;

   In the MAC address table, if the number of changes of the port information corresponding to the source MAC address of the data packet reaches the preset number of times in the first preset time length, a detection packet is constructed, which is a broadcast data packet or a multicast The data packet, the corresponding relationship between the source MAC address of the data packet received by the user plane function UPF and the port information receiving the data packet is recorded in the MAC address table;

   sending the detection packet to the first port, where the detection packet is used to detect whether there is a loop in the network, and the first port is a port in the UPF.
2. The method according to claim 1, further comprising: after sending the detection packet to the first port:

   If the detection packet is received at the first port or other ports of the UPF within the second preset duration, it is determined that there is a loop in the network; otherwise, it is determined that there is no loop in the network .
3. The method according to claim 1 or 2, further comprising:

   Sending the detection packet to the second port, where the port information corresponding to the second port is recorded in the MAC address table and has a corresponding relationship with the source MAC address of the data packet received through the first port before port information, the second port is a port in the UPF.
4. The method according to any one of claims 1 to 3, further comprising:

   When it is determined that there is a loop in the network, report a port loop event to the session management function SMF, where the port loop event includes indication information for indicating the first port;

   receiving an N4 session modification message from the SMF, in which the N4 session modification message instructs the UPF to stop forwarding data packets through the first port, and/or instructs the UPF to perform a loop recovery event;

   According to the N4 session modification message, stop the data forwarding function of the first port, and/or execute the loop recovery event.
5. The method according to claim 4, wherein the port loop event includes indication information for indicating the first port, specifically:

   When the first port is an access port, and an Ethernet protocol data unit PDU session corresponds to an access port, the port loop event carries the identifier of the Ethernet PDU session corresponding to the first port; or,

   When the first port is an N6 port and one network instance corresponds to one N6 port, the port loop event carries the identifier of the network instance corresponding to the first port; or,

   When the first port is the N19 port and the N19 port is an interface between UPFs, the port loop event carries the IP address of the peer UPF.
6. The method according to claim 4 or 5, wherein the executing the loop restoration event comprises:

   Constructing the detection packet again, and sending the detection packet to the first port;

   If the detection packet is not received at the first port or other ports of the UPF within the third preset time period, it means that there is no loop in the network, the network returns to normal, and the loop is reported to the SMF Recover the event; otherwise, continue to execute the step of sending the detection packet to the first port.
7. The method of claim 6, further comprising:

   If the loop still exists in the network within the fourth preset time length, stop the loop detection, and close the data forwarding function of the first port.
8. The method according to claim 6 or 7, further comprising: after reporting the loop recovery event to the SMF:

   receiving an N4 session modification message from the SMF, where the N4 session modification message includes indication information for restoring the data packet forwarding function of the first port;

   Restoring the data packet forwarding function of the first port according to the N4 session modification message.
9. The method according to any one of claims 1 to 8, wherein when the first port is an access port, an N6 port or an N19 port, the method further comprises:

   Receive an N4 session establishment message from the SMF, the N4 session establishment message includes instruction information for performing access port loop detection, or includes instruction information for performing N6 port loop detection, or includes execution N19 port loop detection instructions for the .
10. A loop detection method, characterized in that, comprising:

    receiving a port loop event from the user plane function UPF, where the port loop event includes indication information for indicating the first port;

    Sending alarm information to the operation management and maintenance system OAM, the alarm information is used to indicate that there is a loop in the network, and the alarm information includes indication information for indicating the first port, and the first port is the UPF in the port.
11. The method according to claim 10, wherein the port loop event includes indication information of the first port, specifically:

    When the first port is an access port, and an Ethernet protocol data unit PDU session corresponds to an access port, the port loop event carries the identifier of the Ethernet PDU session corresponding to the first port; or,

    When the first port is an N6 port and one network instance corresponds to one N6 port, the port loop event carries the identifier of the network instance corresponding to the first port; or,

    When the first port is the N19 port and the N19 port is an interface between UPFs, the port loop event carries the IP address of the peer UPF.
12. The method according to claim 10 or 11, wherein when the first port is an access port, further comprising:

    sending to the terminal indication information for releasing the PDU session corresponding to the first port, the indication information carrying the indication information that the reason for releasing the Ethernet PUD session is network looping; or,

    Sending an N4 session modification message to the UPF, where the N4 session modification message instructs the UPF to stop forwarding data packets through the access port, and/or instructs the UPF to perform a loop recovery event.
13. The method according to claim 10 or 11, wherein when the first port is an N6 port or an N19 port, further comprising:

    Sending an N4 session modification message to the UPF, where the N4 session modification message instructs the UPF to stop forwarding data packets through the N6 port or the N19 port, and/or instructs the UPF to perform a loop recovery event.
14. The method according to claim 12 or 13, further comprising:

    receiving a loop recovery event from the UPF;

    Sending a recovery alarm to the OAM, the recovery alarm is used to indicate that there is no loop in the network, and the network returns to normal;

    Sending an N4 session modification message to the UPF, where the N4 session modification message includes indication information for restoring the packet forwarding function of the first port.
15. The method according to any one of claims 10 to 14, wherein when the first port is an access port, an N6 port or an N19 port, the method further comprises:

    Send an N4 session establishment message to the UPF, where the N4 session establishment message includes instructions for performing access port loop detection, or includes instructions for performing N6 port loop detection, or includes instructions for performing N19 port loop detection Instructions.
16. A communication device, characterized by comprising a unit for performing the method according to any one of claims 1-9.
17. A communication device, characterized in that it includes a processor and an interface circuit, the interface circuit is used to receive signals from other communication devices other than the communication device and transmit them to the processor or transfer signals from the processor The signal is sent to other communication devices other than the communication device, and the processor implements the method according to any one of claims 1 to 9 through a logic circuit or executing code instructions.
18. A communication device, characterized by comprising a unit for performing the method according to any one of claims 10-15.
19. A communication device, characterized in that it includes a processor and an interface circuit, the interface circuit is used to receive signals from other communication devices other than the communication device and transmit them to the processor or transfer signals from the processor The signal is sent to other communication devices other than the communication device, and the processor implements the method according to any one of claims 10 to 15 through a logic circuit or executing code instructions.
20. A computer-readable storage medium, characterized in that computer programs or instructions are stored in the storage medium, and when the computer programs or instructions are executed by a communication device, the implementation of any one of claims 1 to 9 method, or implement the method as described in any one of claims 10 to 15.
21. A computer program product comprising instructions, characterized in that, when it runs on a computer, it causes the computer to execute the method according to any one of claims 1 to 9, or to implement any one of claims 10 to 15 method described in the item.

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