Fault detection method, network equipment and system

Abstract

A fault detection method, network device and system, the method comprising: after a first network device receives a BFD message including indication information of an SID list sent by a second network device through a first forwarding path of an SR policy, according to the indication information of the SID list, determining a second forwarding path reversely sharing the same path with the first forwarding path, and a response message of the BFD message is sent to the second network equipment through the second forwarding path, and the second network equipment can perform fault detection on the first forwarding path according to the response message. Therefore, the transmitting end carries the indication information of the SID list in the BFD message, so that the receiving end can determine the forwarding path reversely sharing the same path with the forwarding path for transmitting the BFD message, and sends the response message of the BFD message to the transmitting end based on the determined forwarding path, thereby realizing accurate fault detection of the specific forwarding path in the SR policy.

Description

[0001] This application is a divisional application of a Chinese patent application with the application number 202110128378.X and the invention title "A Fault Detection Method, Network Device and System", which was filed on January 29, 2021, and the entire content is incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technologies, and in particular, to a fault detection method, network device, and system. Background Art

[0003] Bidirectional Forwarding Detection (BFD), as a mechanism that can perform end-to-end detection quickly, is widely used for fault detection of Segment Routing Policy (SRpolicy).

[0004] Currently, the process of fault detection by the BFD mechanism includes: the sender sends a BFD message to the reflector through the SR policy and requests the reflector to feedback a response message of the BFD message to the sender, so as to determine whether there is a fault in the SR policy. Since the SR policy is a unidirectional tunnel, the response message of the BFD message is usually transmitted through the Internet Protocol (IP) routing method, and the transmission path of the response message determined by the IP routing method (which can also be called the IP path) is very likely not to pass through the network devices passed by the SR policy. That is, the transmission of the BFD message and the response message of the BFD message is not on the same path. In this way, when a device on the IP path fails, the response message cannot reach the sending segment, resulting in the sender misjudging that the SR policy has failed, thereby reducing the accuracy of the detection result for the SR policy.

[0005] Based on this, there is an urgent need to provide a fault detection method that not only utilizes the characteristic that the BFD mechanism can complete detection quickly but also can overcome the problem that the non - co - path transmission of the BFD message and the response message leads to inaccurate BFD detection results, so as to realize more accurate fault detection of the SR policy by the BFD mechanism. Summary of the Invention

[0006] Based on this, the present application provides a fault detection method, a network device, and a system. By carrying indication information of a segment identification list (SID list) in a BFD packet, the receiving end can determine a forwarding path that is reverse common with the forwarding path for transmitting the BFD packet based on the indication information of the SID list in the BFD packet, and send a response packet of the BFD packet to the transmitting end based on the determined forwarding path, so as to realize fault detection of a specific forwarding path in an SR policy, thereby improving the accuracy and precision of the BFD mechanism for fault detection.

[0007] In the present application, BFD detection may refer to, for example, static BFD detection, dynamic BFD detection, or seamless bidirectional forwarding detection (SBFD) detection.

[0008] In a first aspect, the present application provides a fault detection method, which is applied to a first network device. When there is a first SR policy between a second network device and the first network device and the second network device needs to perform fault detection on a first forwarding path in the first SR policy, the method may include, for example: the first network device receives a first BFD packet including indication information of a first SID list sent by the second network device through a first forwarding path of the first SR policy. At this time, the first network device may determine a second forwarding path that is reverse common with the first forwarding path according to the indication information of the first SID list in the first BFD packet, and send a first response packet of the first BFD packet to the second network device through the second forwarding path. The first response packet is used to instruct the second network device to perform fault detection on the first forwarding path. In this way, through this method, the transmitting end (i.e., the second network device) of the BFD detection carries the indication information of the SID list in the BFD packet, so that the receiving end (i.e., the first network device) can determine a forwarding path that is reverse common with the forwarding path for transmitting the BFD packet based on the indication information of the SID list, and send a response packet of the BFD packet to the transmitting end based on the determined forwarding path. By ensuring that the actual forwarding paths of the BFD packet and the response packet are reverse common, accurate fault detection of a specific forwarding path in the SR policy is realized, and the accuracy and precision of the BFD mechanism for fault detection of the SR policy are improved.

[0009] Among them, the SR policy can be an SR-MPLS policy, corresponding to the multi-protocol label switching (MPLS) network scenario; or, the SR policy can also be an SRv6 policy, corresponding to the internet protocol version 6 (IPv6). In the SR-MPLS policy scenario, the SID list corresponds to the MPLS label stack, and the SID list can include at least one MPLS label corresponding to a network device or link; in the SRv6 policy scenario, the SID list corresponds to a list of IPv6 addresses, and the SID list can include at least one IPv6 address corresponding to a network device or link.

[0010] For any two reverse common paths of SR policies, it can mean that the order of the network devices and links sequentially passed by the two tunnels determined according to the two SR policies is opposite. For a certain two forwarding paths in any two SR policies that are reverse common paths, it can mean that the order of the network devices and links sequentially passed by the two forwarding paths determined according to the two SID lists corresponding to the two forwarding paths is opposite. As per the existing design, the two forwarding paths of the reverse common path can belong to two SR policies respectively. However, it can be understood that in other possible implementations, for example, when the round-trip path between two endpoints is defined as belonging to a complete SR policy, it can also be considered that the two forwarding paths belong to the same SR policy.

[0011] In a possible implementation manner, before the first network device receives the first BFD packet sent by the second network device through the first forwarding path of the first SR policy, the method can further include: the first network device generates indication information of the first SID list. Or, the first network device receives the indication information of the first SID list sent by the second network device. In this way, the first network device can save the correspondence between the indication information of the first SID list and the second forwarding path, and is prepared to determine the second forwarding path according to the indication information of the first SID list in the first BFD packet after receiving the first BFD packet.

[0012] In another possible implementation, the method may further include: a first network device receives a message sent by a control and management device, where the message includes indication information of a first SID list. In addition, the message further includes indication information of a second SID list, where the indication information of the second SID list indicates the first forwarding path, and the indication information of the first SID list indicates the second forwarding path; or, the indication information of the second SID list indicates the second forwarding path, and the indication information of the first SID list indicates the first forwarding path.

[0013] As an example, the message may be a border gateway protocol segment routing policy (BGPSR policy) message, and the BGPSR policy message may carry the indication information of the first SID list through a sub type length value (sub-TLV) field. If the BGPSR policy message further carries the indication information of the second SID list, then, the indication information of the first SID list and the indication information of the second SID list may be carried in one sub-TLV field in the BGPSR policy message, or, the indication information of the first SID list and the indication information of the second SID list may also be carried in two different sub-TLV fields in the BGPSR policy message respectively. It should be noted that the message used to carry the indication information of the first SID list may be, in addition to the BGPSR policy message, also a network configuration protocol (NETCONF) or a path computation element protocol (PCEP) message, etc.

[0014] In this implementation manner, the indication information of the first SID list may also be allocated and sent by the second network device to the control and management device, and then sent by the control and management device to the first network device. As an example, the second network device sends the indication information of the first SID list to the control and management device. For example, the indication information of the first SID list may be carried in a border gateway protocol link state (BGP-LS) message, and the indication information of the first SID list is carried through the sub-TLV field in the BGP-LS message. If the indication information of the second SID list is also carried in the BGP-LS message, then, the indication information of the first SID list and the indication information of the second SID list may be carried in one sub-TLV field in the BGP-LS message, or, the indication information of the first SID list and the indication information of the second SID list may also be carried in two different sub-TLV fields in the BGP-LS message respectively. It should be noted that when the second network device sends the indication information of the first SID list to the control and management device, the message used to carry the indication information of the first SID list may be, in addition to the BGP-LS message, also a NETCONF or PCEP message, etc.

[0015] In a possible implementation manner, the indication information of the first SID list may be used to indicate the SID list corresponding to the second forwarding path. Then, after receiving the first BFD message, the first network device may directly determine, according to the indication information of the first SID list, the second forwarding path for transmitting the first response message corresponding to the first BFD message, making it possible to implement accurate BFD detection.

[0016] In another possible implementation, the indication information of the first SID list can also be used to indicate the SID list corresponding to the first forwarding path. In one case, the first network device can store the correspondence between the indication information of the first SID list and the second forwarding path. Then, after receiving the first BFD packet, the first network device can directly determine the second forwarding path corresponding to the indication information of the first SID list according to the indication information of the first SID list. In another case, the first network device can also store the correspondence between the indication information of the first SID list and the indication information of the second SID list, and the indication information of the second SID list is used to indicate the SID list corresponding to the second forwarding path. Then, the first network device determines the second forwarding path according to the indication information of the first SID list. For example, it may include: the first network device determines the indication information of the second SID list according to the indication information of the first SID list; then, the first network device determines the second forwarding path according to the indication information of the second SID list. In this way, it becomes possible to achieve accurate BFD detection.

[0017] It should be noted that in some possible situations, if there is a fault in the network device or link through which the second forwarding path passes, or if there is a fault in the network device or link through which the first forwarding path passes, then the second network device may not be able to receive the first response packet. Then, if the second network device does not receive the first response packet through the second forwarding path within a preset time (such as 1 second), since the first forwarding path and the second forwarding path are reverse common paths, it is still possible to determine that the first forwarding path is faulty. In some other possible situations, if the network devices and links through which the first forwarding path and the second forwarding path pass are all normal, then the second network device can receive the first response packet. In this case, the second network device determines that both the first forwarding path and the second forwarding path for transmitting the first BFD packet and the first response packet are normal according to the received first response packet, that is, it can be determined that the first forwarding path is not faulty.

[0018] In some possible implementations, the method may further include: The first network device sends a second BFD packet to the second network device through a second forwarding path of a second SR policy, where the second BFD packet includes indication information of a third SID list, and the indication information of the third SID list is used to instruct the first network device to determine a first forwarding path for sending a second response packet to the second BFD packet; the first network device receives the second response packet from the first forwarding path; the first network device performs a fault detection on the second forwarding path according to the second response packet. In this way, through this method, bidirectional BFD detection of a specific forwarding path in the SR policy can be accurately implemented.

[0019] In some other possible implementations, the method may further include: The first network device receives a third BFD packet sent by the second network device through a third forwarding path of a first SR policy, where the third BFD packet includes indication information of a fourth SID list, and the third forwarding path is different from the first forwarding path; the first network device determines a fourth forwarding path according to the indication information of the fourth SID list, and the fourth forwarding path is reverse common path with the third forwarding path; the first network device sends a third response packet of the third BFD packet to the second network device through the fourth forwarding path, and the third response packet is used to instruct the second network device to perform a fault detection on the third forwarding path. In this way, through this method, BFD detection of a specific forwarding path in the SR policy including multiple forwarding paths can be implemented, and the detection accuracy of BFD detection is improved. In the embodiments of the present application, the indication information of the first SID list may be a path segment or a bonding SID (BSID); alternatively, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a path segment or a BSID or the second SID list itself.

[0020] Second aspect, the present application further provides a fault detection method, which is applied to a second network device. When there is a first SR policy between the second network device and the first network device and the second network device needs to perform fault detection on the first forwarding path in the first SR policy, this method may include, for example: The second network device sends a BFD packet including indication information of a first SID list to the first network device through the first forwarding path of the first SR policy, and the indication information of the first SID list is used to instruct the first network device to determine a second forwarding path for sending a response packet of the BFD packet, and the second forwarding path and the first forwarding path are reverse common paths; If the second network device receives a response packet of the BFD packet from the second forwarding path, then the second network device performs fault detection on the first forwarding path according to the response packet. In this way, through this method, the transmitter of the BFD detection (i.e., the second network device) carries the indication information of the SID list in the BFD packet, so that the receiver (i.e., the first network device) can determine a forwarding path that is reverse common to the forwarding path for transmitting the BFD packet based on the indication information of the SID list, and send a response packet of the BFD packet to the transmitter based on the determined forwarding path. By ensuring that the actual forwarding paths of the BFD packet and the response packet are reverse common paths, accurate fault detection of the specific forwarding path in the SR policy is achieved, and the accuracy and precision of the BFD mechanism for fault detection of the SR policy are improved.

[0021] In a possible implementation manner, before the second network device sends a BFD packet to the first network device through the first forwarding path of the first SR policy, this method may further include: The second network device receives the indication information of the first SID list sent by the first network device.

[0022] In another possible implementation manner, before the second network device sends a BFD packet to the first network device through the first forwarding path of the first SR policy, this method may further include: The second network device generates the indication information of the first SID list. In this implementation manner, the second network device may further send the indication information of the first SID list to the first network device, which provides a guarantee for the implementation of the fault detection method provided in the embodiments of the present application.

[0023] In yet another possible implementation, before the second network device sends a BFD packet to the first network device through the first forwarding path of the first SR policy, the method may further include: the second network device receives indication information of a first SID list sent by a control and management device. In one case, the control and management device may generate the indication information of the first SID list and send it to the second network device; in another case, the indication information of the first SID list may also be generated by the second network device and sent to the control and management device, and then sent by the control and management device to the second network device. As an example, the second network device sending the indication information of the first SID list to the control and management device may include: the second network device sending a BGP-LS packet to the control and management device, and the BGP-LS packet carries the indication information of the first SID list through a sub-TLV field; the second network device receiving the indication information of the first SID list sent by the control and management device may include: the second network device receiving a BGPSR policy packet sent by the control and management device, and the BGPSR policy packet carries the indication information of the SID list through a sub-TLV field.

[0024] In this application, the indication information of the first SID list may be a Path Segment or a BSID; alternatively, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a Path Segment or a BSID or the second SID list itself.

[0025] In a third aspect, this application provides a fault detection device, which is applied to the first network device. The device may include: a receiving unit, a determining unit, and a sending unit. Among them, the receiving unit is configured to receive a first Bidirectional Forwarding Detection (BFD) packet sent by the second network device through the first forwarding path of the first Segment Routing policy (SRpolicy), and the first BFD packet includes indication information of a first Segment ID list (SID list); the determining unit is configured to determine a second forwarding path according to the indication information of the first SID list, and the second forwarding path and the first forwarding path are reverse common paths; the sending unit is configured to send a first response packet of the first BFD packet to the second network device through the second forwarding path, and the first response packet is used to instruct the second network device to perform a fault detection on the first forwarding path.

[0026] In a possible implementation, the apparatus may further include a generating unit. The generating unit is configured to generate indication information of the first SID list before receiving a first BFD packet sent by a second network device through a first forwarding path of a first SR policy.

[0027] In a possible implementation, the receiving unit is further configured to receive the indication information of the first SID list sent by the second network device.

[0028] In a possible implementation, the receiving unit is further configured to receive a message sent by a control and management device, where the message includes the indication information of the first SID list. As an example, the message further includes indication information of a second SID list, where the indication information of the second SID list indicates the first forwarding path, and the indication information of the first SID list indicates the second forwarding path; or, the indication information of the second SID list indicates the second forwarding path, and the indication information of the first SID list indicates the first forwarding path. The message may be, for example, a BGP SR policy packet, and the BGP SR policy packet carries the indication information of the first SID list through a sub-TLV field.

[0029] As an example, the indication information of the first SID list is used to indicate the SID list corresponding to the second forwarding path.

[0030] As another example, the indication information of the first SID list is used to indicate the SID list corresponding to the first forwarding path. The determining unit is specifically configured to: determine the indication information of the second SID list according to the indication information of the first SID list; and determine the second forwarding path according to the indication information of the second SID list.

[0031] In a possible implementation, the sending unit is further configured to send a second BFD packet to the second network device through the second forwarding path of a second SR policy. The second BFD packet includes indication information of a third SID list, and the indication information of the third SID list is used to indicate the first network device to determine the first forwarding path for sending a second response packet to the second BFD packet; the receiving unit is further configured to receive the second response packet from the first forwarding path; then, the apparatus further includes a detecting unit, and the detecting unit is configured to perform a fault detection on the second forwarding path according to the second response packet.

[0032] In a possible implementation, the receiving unit is further configured to receive, via a third forwarding path of the first SR policy, a third BFD packet sent by the second network device, where the third BFD packet includes indication information of a fourth SID list, and the third forwarding path is different from the first forwarding path; the determining unit is further configured to determine a fourth forwarding path according to the indication information of the fourth SID list, and the fourth forwarding path and the third forwarding path are reverse common paths; the sending unit is further configured to send, via the fourth forwarding path, a third response packet of the third BFD packet to the second network device, where the third response packet is used to instruct the second network device to perform a fault detection on the third forwarding path.

[0033] Among them, the indication information of the first SID list may be a Path Segment or a BSID; alternatively, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a Path Segment or a BSID or the second SID list itself.

[0034] The fault detection device provided in this third aspect is used to perform the related operations mentioned in the first aspect above. For its specific implementation manner and achieved effects, reference may be made to the relevant descriptions in the first aspect above, which will not be elaborated here.

[0035] In a fourth aspect, the present application further provides a fault detection device, which is applied to a second network device. The device may include: a sending unit, a receiving unit, and a detecting unit. Among them, the sending unit is configured to send a BFD packet to a first network device via a first forwarding path of a first SR policy, where the BFD packet includes indication information of a first SID list, and the indication information of the first SID list is used to instruct the first network device to determine a second forwarding path for sending a response packet of the BFD packet, and the second forwarding path and the first forwarding path are reverse common paths; the receiving unit is configured to receive the response packet of the BFD packet from the second forwarding path; the detecting unit is configured to perform a fault detection on the first forwarding path according to the response packet.

[0036] In a possible implementation, the receiving unit is further configured to receive the indication information of the first SID list sent by the first network device before sending the BFD packet to the first network device via the first forwarding path of the first SR policy.

[0037] In a possible implementation, the receiving unit is further configured to receive the indication information of the first SID list sent by the control and management device before sending the BFD packet to the first network device through the first forwarding path of the first SR policy. As an example, specifically, the receiving unit is configured to: receive the BGPSR policy packet sent by the control and management device, and the BGPSR policy packet carries the indication information of the SID list through the sub-TLV field. In this implementation, the sending unit is further configured to send the indication information of the first SID list to the control and management device before receiving the indication information of the first SID list sent by the control and management device. Specifically, the sending unit is configured to: send a BGP-LS packet to the control and management device, and the BGP-LS packet carries the indication information of the first SID list through the sub-TLV field.

[0038] In a possible implementation, the apparatus further includes a generating unit, and the generating unit is configured to generate the indication information of the first SID list. Then, the sending unit is further configured to send the indication information of the SID list to the first network device.

[0039] The indication information of the first SID list may be a Path Segment or a BSID; or, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a Path Segment or a BSID or the second SID list itself.

[0040] The fault detection apparatus provided in the fourth aspect is used to perform the related operations mentioned in the second aspect above. For its specific implementation manner and achieved effects, reference can be made to the related description in the second aspect above, which will not be elaborated here.

[0041] In a fifth aspect, the present application further provides a network device, which includes: a processor for enabling the network device to implement the method provided in the first aspect or the second aspect above. The network device may further include a memory, and the memory is coupled to the processor. When the processor executes the instructions stored in the memory, it can enable the network device to implement the method provided in the first aspect or the second aspect above. The network device may further include a communication interface, and the communication interface is used for the network device to communicate with other devices. Exemplarily, the communication interface may be a transceiver, a circuit, a bus, a module or other types of communication interfaces. In the present application, the instructions in the memory may be pre-stored, or may be stored after being downloaded from the Internet when using the network device. The present application does not specifically limit the source of the instructions in the memory.

[0042] In a sixth aspect, the present application further provides a network system, which includes a first network device and a second network device, where: the first network device is configured to execute the method provided in the first aspect above; the second network device is configured to execute the method provided in the second aspect above.

[0043] In a seventh aspect, the present application provides a chip, including a processor and an interface circuit; the interface circuit is configured to receive instructions and transmit them to the processor; the processor is configured to execute the instructions corresponding to the method provided in the first aspect or the second aspect.

[0044] In an eighth aspect, the present application provides a computer-readable storage medium, which stores program codes or instructions. When it runs on a computer, it causes the computer to execute the method provided in the first aspect or the second aspect above.

[0045] In a ninth aspect, the present application provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the method provided in the first aspect or the second aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0047] Figure 1 It is a schematic structural diagram of a network system in an embodiment of the present application;

[0048] Figure 2 It is a schematic structural diagram of an SR policy in an embodiment of the present application;

[0049] Figure 3 It is a flowchart of a fault detection method 100 in an embodiment of the present application;

[0050] Figure 4a It is a schematic format diagram of a sub-TLV field in a BGPSR policy message in an embodiment of the present application;

[0051] Figure 4b It is a schematic format diagram of another sub-TLV field in a BGPSR policy message in an embodiment of the present application;

[0052] Figure 4c In an embodiment of the present application Figure 4a or Figure 4bSchematic diagram of a format of the Value field in the sub-TLV field;

[0053] Figure 5a Schematic diagram of a format of the SID list TLV field in a BGP-LS message in an embodiment of the present application;

[0054] Figure 5b Schematic diagram of a format of the sub-TLV field in a SID list TLV field in an embodiment of the present application;

[0055] Figure 5c Schematic diagram of a format of the sub-TLV field in another SID list TLV field in an embodiment of the present application;

[0056] Figure 6a Schematic diagram of a format of a BFD message c and a response message C in an embodiment of the present application;

[0057] Figure 6b Schematic diagram of a format of a BFD message d and a response message D in an embodiment of the present application;

[0058] Figure 6c Schematic diagram of a format of a BFD message e and a response message E in an embodiment of the present application;

[0059] Figure 7 Schematic diagram of a structure of a fault detection device 700 in an embodiment of the present application;

[0060] Figure 8 Schematic diagram of a structure of a fault detection device 800 in an embodiment of the present application;

[0061] Figure 9 Schematic diagram of a structure of a network device 900 in an embodiment of the present application;

[0062] Figure 10 Schematic diagram of a structure of a network device 1000 in an embodiment of the present application;

[0063] Figure 11 Schematic diagram of a structure of a network system 1100 in an embodiment of the present application. Detailed implementation manners

[0064] Currently, in the process of performing BFD detection on an SR policy, the BFD message is transmitted from the transmitting end to the receiving end through the SR policy to be detected. However, when the receiving end sends the response message of the BFD message, it determines the path of the response message from the receiving end to the transmitting end through the IP routing method, and sends the response message to the transmitting end through the path determined according to the IP routing method, and the transmitting end performs fault detection on the SR policy based on the response message.

[0065] For example, in the Figure 1 network system shown, it may include customer edge (CE) devices 01 and 02, provider edge (PE) devices 11 and 12, provider (P) devices 21, 22, 23, and 24. Among them, PE device 11 is connected to CE device 01. PE device 11 is connected to PE device 12 through P devices 21 and 22 in sequence, and PE device 11 is also connected to PE device 12 through P devices 23 and 24 in sequence. PE device 12 is connected to CE device 02. Assume that there are SR policy 1 and SR policy 2 between PE device 11 and PE device 12. Among them, PE device 11 is the ingress node of SR policy 1 and SR policy 2, and PE device 12 is the egress node of SR policy 1 and SR policy 2. For ease of description, the following two examples take that both SR policy 1 and SR policy 2 include a forwarding path as an example. The BFD detection of this one forwarding path can thus also be referred to as the BFD detection of the SR policy. SR policy 1 includes P devices 21 and 22, and SR policy 2 includes P devices 23 and 24.

[0066] As an example, when the PE device 11 needs to perform BFD detection on the SR policy 1, the operations performed may include: S11, the PE device 11 sends a BFD packet a to the PE device 12 through the SR policy 1; S12, the PE device 12 sends a response packet A corresponding to the BFD packet a to the PE device 11 through the IP routing method successively via the P device 24 and the P device 23, that is, the IP path 1 through which the response packet A passes successively passes through the PE device 12, the P device 24, the P device 23, and the PE device 11. On the one hand, if a network device or link through which the IP path 1 passes fails, such as the P device 23 fails, the P device 24 fails, or at least one link included in the IP path 1 fails, it may cause the PE device 11 to not receive the response packet A within a preset time, thereby erroneously determining that the SR policy 1 fails. On the other hand, even if the PE device 11 receives the response packet A, for scenarios such as two-way detection, since the BFD packet a and the response packet A are not transmitted on the same path, it may also erroneously determine that the SR policy 1 is normal when the IP path 1 is not faulty. In this example, since the network devices passed by the SR policy 1 and the IP path 1 are not exactly the same, the current BFD detection result cannot accurately reflect the fault condition of the SR policy 1.

[0067] As another example, the operations performed for BFD detection on the SR policy 1 and the SR policy 1' (not shown in the figure) may include: S21, the PE device 11 sends a BFD packet a and a BFD packet a' to the PE device 12 through the SR policy 1 and the SR policy 1' respectively; S22, the PE device 12 sends a response packet A corresponding to the BFD packet a and a response packet A' corresponding to the BFD packet a' to the PE device 11 through the IP routing method successively via the P device 24 and the P device 23, that is, the response packet A and the response packet A' are both transmitted through the IP path 1. In this example, for the SR policy 1 and the SR policy 2, the determined IP path 1 based on the IP routing method is the same. Thus, even if the devices or links passed by the SR policy 1 do not fail, while the devices or links passed by the SR policy 1' fail, since the transmission paths of the BFD response packets of the SR policy 1 and the SR policy 1' are both the IP path 1, as long as a device or link included in the IP path 1 fails, the PE11 will determine that the SR policy 1 and the SR policy 1' are faulty according to the non-receipt of the response packet. This results in the inability to achieve fine-grained detection at the path level.

[0068] Based on this, an embodiment of the present application provides a fault detection method. If a second network device needs to perform BFD detection on a first forwarding path in a first SR policy to a first network device, the operations performed may include, for example: the second network device sends a first BFD packet to the first network device through the first forwarding path of the first SR policy, and the first BFD packet includes indication information of a first SID list; when the first network device receives the first BFD packet, it can determine a second forwarding path that is reverse co-path with the first forwarding path according to the indication information of the first SID list. Thus, the first network device can send a first response packet of the first BFD packet to the second network device through the second forwarding path, and the first response packet is used to instruct the second network device to perform fault detection on the first forwarding path. In this way, the transmitting end of the BFD detection carries the indication information of the SID list in the BFD packet, so that the receiving end can determine a forwarding path that is reverse co-path with the forwarding path for transmitting the BFD packet based on the indication information of the SID list, and send a response packet of the BFD packet to the transmitting end based on the determined forwarding path. By ensuring that the actual forwarding paths of the BFD packet and the response packet are reverse co-path, accurate fault detection of the specific forwarding path in the SR policy is achieved, and the accuracy and precision of the BFD mechanism for fault detection of the SR policy are improved.

[0069] To facilitate understanding of the embodiments of the present application, the meanings of some concepts involved in the embodiments of the present application are explained below.

[0070] An SR policy is a tunnel applicable to SR. An SR policy may include at least one candidate path, and each candidate path includes at least one forwarding path. When traffic is forwarded through an SR policy, the preference values of the candidate paths of the SR policy can be checked first, and the candidate path with the highest preference value is selected as the effective candidate path (which can also be called the active candidate path); then, if there is one forwarding path in the effective candidate path, the traffic is sent through the SID list corresponding to the forwarding path. If there are at least two forwarding paths in the effective candidate path, the load sharing ratio of each forwarding path for the traffic is determined according to the weights corresponding to the SID lists of each forwarding path, and the traffic corresponding to the corresponding ratio is sent through the SID lists corresponding to each forwarding path.

[0071] Take Figure 1 the SR policy 1 shown as an example. Assume that the SR policy 1 is as Figure 2As shown in the figure, it includes candidate path 31 and candidate path 32. Among them, candidate path 31 includes forwarding path 311 and forwarding path 312, and candidate path 32 includes forwarding path 321, forwarding path 322 and forwarding path 323. The preference value corresponding to candidate path 31 is 7, and the preference value corresponding to candidate path 32 is 2. The weights corresponding to forwarding path 311 and forwarding path 312 are 0.6 and 0.4 respectively, and the weights corresponding to forwarding path 321, forwarding path 322 and forwarding path 323 are 0.3, 0.4 and 0.3 respectively. The SID lists corresponding to forwarding path 311, forwarding path 312, forwarding path 321, forwarding path 322 and forwarding path 323 are SID list1 to SID list 5 respectively. Then, for the traffic transmitted through SR policy 1, when SR policy 1 is normal, this traffic will be divided into traffic x and traffic y in a ratio of 6:4. Among them, traffic x is transmitted through forwarding path 311 in SR policy 1, and traffic y is transmitted through forwarding path 312 in SR policy 1.

[0072] Among them, the SR policy can be an SR-MPLS policy, corresponding to the multi-protocol label switching (MPLS) network scenario; or, the SR policy can also be an SRv6 policy, corresponding to the internet protocol version 6 (IPv6). In the SR-MPLS policy scenario, the SID list corresponds to the MPLS label stack, and this SID list can include at least one MPLS label corresponding to a network device or link; in the SRv6 policy scenario, the SID list corresponds to a list of IPv6 addresses, and this SID list can include at least one IPv6 address corresponding to a network device or link. For the traffic that needs to be transmitted through this SR Policy 1, the corresponding SID list will be pushed into the packet header of the traffic.

[0073] The reverse common path can include the SR policy reverse common path (such as the case where the SR policy only includes one forwarding path) and the reverse common path of a certain forwarding path in the SR policy (such as the case where the SR policy includes multiple forwarding paths). For the SR policy reverse common path, it can refer to the order of the network devices and links passed through in sequence determined according to two SR policies being opposite. For example, in Figure 1In the network system shown, SR policy 1 sequentially includes PE device 11, the link between PE device 11 and P device 21, P device 21, the link between P device 21 and P device 22, P device 22, the link between P device 22 and PE device 12, and PE device 12. And SR policy 3 sequentially includes PE device 12, the link between PE device 12 and P device 22, P device 22, the link between P device 22 and P device 21, P device 21, the link between P device 21 and PE device 11, and PE device 11. Thus, SR policy 1 and SR policy 3 are determined to be reverse common-path tunnels. For the reverse common path of the forwarding path in the SR policy, it can refer to two forwarding paths with opposite orders of SIDs included in the SID list corresponding to the forwarding path. The forwarding paths of the reverse common path can belong to two SR policies of the reverse common path respectively. For example, taking the SIDs included in the SID list as the MPLS labels corresponding to the network devices, in Figure 1 the network system shown, the forwarding path 41 in SR policy 1 corresponds to the SID list <41021, 41022, 41012>. Among them, 41021, 41022, and 41012 are the SIDs corresponding to P device 21, P device 22, and PE device 12 in SR policy 1 respectively. The forwarding path 42 corresponds to the SID list <42022, 42021, 42011>. Among them, 42022, 42021, and 42011 are the SIDs corresponding to P device 22, P device 21, and PE device 11 in SR policy 3 respectively. It can be seen that the order of the network devices determined by the forwarding path 41 and the forwarding path 42 according to the corresponding SID list is opposite. Among them, the forwarding path 42 can belong to SR policy 3 which is reverse common-path with SR policy 1. Thus, the forwarding path 41 and the forwarding path 42 are determined to be forwarding paths of the reverse common path. It should be noted that the order of the SIDs included in the two SID lists corresponding to the two forwarding paths of the reverse common path is not necessarily the opposite order. The content of the SIDs included in the two SID lists can be substantially completely different, but the network devices and links passed by the forwarding paths determined according to the SIDs included in the two SID lists respectively are the same. For example, in the above example, the SID list of the forwarding path 42 is not <41012, 41022, 41021>, but <42022, 42021, 42011>, but the order of the network devices indicated by <42022, 42021, 42011> is opposite to the order of the network devices indicated by the SID list of the forwarding path 41.

[0074] It should be noted that the SIDs included in the SID list corresponding to the forwarding path may include the SIDs corresponding to the network devices on the forwarding path. For example, the SID list corresponding to forwarding path 41 includes: the SID corresponding to P device 21, the SID corresponding to P device 22, and the SID corresponding to PE device 12; alternatively, the SIDs included in the SID list corresponding to the forwarding path may also include the SIDs corresponding to the links in the forwarding path. For example, the SID list corresponding to forwarding path 41 includes: the SID corresponding to the link from PE device 11 to P device 21, the SID corresponding to the link from P device 21 to P device 22, and the SID corresponding to the link from P device 22 to PE device 12; or, the SIDs included in the SID list corresponding to the forwarding path may also include both the SIDs corresponding to the network devices on the forwarding path and the SIDs corresponding to the links on the forwarding path. Again, for example, the SID list corresponding to forwarding path 41 includes: the SID corresponding to the link from PE device 11 to P device 21, the SID corresponding to P device 22, and the SID corresponding to the link from P device 22 to PE device 12; or, the SID list corresponding to forwarding path 41 includes: the SID corresponding to the link from PE device 11 to P device 21, the SID corresponding to P device 21, the SID corresponding to the link from P device 21 to P device 22, the SID corresponding to P device 22, the SID corresponding to the link from P device 22 to PE device 12, and the SID corresponding to PE device 12; or, the SID list corresponding to the forwarding path may also be other possible situations, such as other possible reasonable types, arrangement methods, or combinations of different types.

[0075] The types of SIDs included in the SID lists corresponding to the two forwarding paths of the reverse common path can be the same or different. For example, as a simple implementation, the SID list corresponding to forwarding path 41 includes the SIDs of each network device and each link in this forwarding path 41, and the SID list corresponding to the forwarding path 42 that is reverse common to this forwarding path includes the SIDs of each network device and each link in this forwarding path 42. For another example, for the case where the cost values of each link are the same, the SID list corresponding to forwarding path 41 can include the SIDs corresponding to each network device in this forwarding path 41, but not the SIDs of each link, and the SID list corresponding to the forwarding path 42 that is reverse common to this forwarding path includes the SIDs of each network device in this forwarding path 42. For yet another example, the SID list corresponding to forwarding path 41 includes the SIDs of each link in this forwarding path 41, and the SID list corresponding to the forwarding path 42 that is reverse common to this forwarding path includes the SIDs of each network device in this forwarding path 42, or the SID list corresponding to forwarding path 42 includes both the SIDs corresponding to the network devices in this forwarding path 42 and the SIDs corresponding to the links in this forwarding path 42. Even in some possible scenarios, it is also allowed that the SID list corresponding to forwarding path 41 is only used to carry the SIDs indicating some network devices and / or links on forwarding path 41, and the SID list corresponding to forwarding path 42 is also only used to carry the SIDs indicating some network devices and / or links on forwarding path 42, and it is allowed that they are different from the network devices and / or links indicated in the SID list corresponding to forwarding path 41, but the reverse common forwarding paths 41 and 42 can still be determined based on these two SID lists and the network topology. The above is only an example, and the content included in the two SID lists can also be designed in other ways in combination with the application scenario, as long as the two reverse common forwarding paths with opposite orders of appearance of network devices and links can be determined based on the two SID lists.

[0076] The above description involves the case of two reverse common forwarding paths with the same network devices and links passed by the paths. In other possible settings, it is also allowed to appropriately relax the conditions that the two paths of the reverse common path need to meet within a reasonable range in combination with the actual application scenario, network structure, device deployment, etc., such as taking meeting a certain proportion of passing the same network devices and / or links as the setting condition, or taking passing certain specific same network devices and / or links as the setting condition, etc. These settings should be reasonable in the corresponding network scenario and can improve the detection accuracy of BFD compared with the method of completely forwarding response messages based on IP mentioned in the background art of this application.

[0077] For example, inFigure 1 In the network system shown, according to the fault detection method provided in the embodiments of the present application, the process of performing BFD detection on the forwarding path 41 in the SR policy 1 may include: S31, the PE device 11 sends a BFD packet c to the PE device 12 through the forwarding path 41 of the SR policy 1, and the BFD packet c includes the indication information p of the SID list; S32, after receiving the BFD packet c, the PE device 12 determines the forwarding path 42 that is reverse common-path with the forwarding path 41 according to the indication information of the SID list in the BFD packet c; S33, the PE device 12 sends a response packet C of the BFD packet c to the PE device 11 through the forwarding path 42; S34, if the PE device 11 receives the response packet C, it can perform fault detection on the forwarding path 41 based on the response packet C, for example, determine that the forwarding path 41 is normal; S35, if the PE device 11 does not receive the response packet C within a preset time, it can determine that the forwarding path 41 fails. Since the transmission paths of the response packet C and the BFD packet c are reverse common-path, the accuracy of the BFD detection result can be ensured. Thus, in the BFD detection of the SR policy, not only can it be ensured that the transmission of the BFD packet and the corresponding response packet can be reverse common-path to achieve accurate fault detection, but also the fault detection can be performed on any forwarding path in the SR policy, realizing a more fine-grained and accurate BFD detection.

[0078] In Figure 1 In the network system shown, the PE devices can be indirectly connected through one or more forwarding devices, where the forwarding devices include but are not limited to P devices.

[0079] It should be noted that the network devices in the embodiments of the present application may refer to devices such as routers, switches, forwarders, and firewalls that can carry services.

[0080] It should be noted that the methods provided in the embodiments of the present application can be applied to scenarios with bidirectional virtual private network (VPN) connection services. In this scenario, a VPN service and a carried tunnel are deployed between the PE devices, and BFD detection is started for the tunnel to achieve fast fault detection. Among them, the tunnel carried between the PE devices can be of types such as SRv6 policy or SR-MPLS policy, etc.

[0081] It should be noted that the method provided in the embodiments of the present application can support, for example, static BFD detection, dynamic BFD detection, or seamless bidirectional forwarding detection (SBFD). BFD packets can be used to detect the connectivity of the path carrying services.

[0082] To facilitate understanding of the fault detection method provided in the embodiments of the present application, the method will be described below with reference to the accompanying drawings.

[0083] Figure 3 FIG. 100 is a schematic flow chart of a fault detection method 100 provided in an embodiment of the present application. The method 100 can be applied to a network scenario including a first network device and a second network device. As an example, the first network device can be the egress PE device of the SR policy to be detected, and the second network device can be the ingress PE device of the SR policy. For ease of understanding, in the structure of the network system shown in Figure 1 FIG. 1, the interaction mode between the PE device 11 and the PE device 12 when detecting the forwarding path 41 in the SR policy 1 is used to describe the embodiments of the present application, where the first network device corresponds to Figure 1 the PE device 12 in FIG. 1, and the second network device corresponds to the PE device 11. Specifically, the method 100 can include the following S101 to S106:

[0084] S101, the PE device 11 sends a BFD packet c to the PE device 12 through the forwarding path 41 of the SR policy 1, and the BFD packet c includes the indication information of the first SID list.

[0085] S102, the PE device 12 receives the BFD packet c sent by the PE device 11 through the forwarding path 41 of the SR policy 1.

[0086] The indication information of the first SID list can be the first SID list itself. For example, the indication information of the first SID list can be the SID list corresponding to the forwarding path 42: <42022, 42021, 42011>. Alternatively, the indication information of the first SID list can also be the identifier of the first SID list. The identifier of the first SID list can include, but is not limited to, the path segment (Path Segment) corresponding to the first SID list or the bonding SID (BSID) corresponding to the first SID list. For example, the indication information of the first SID list can be the BSID: 420 that can indicate the <42022, 42021, 42011>.

[0087] Before S101, the indication information of the first SID list can be saved on the PE device 11 and the PE device 12 to cooperate with the implementation of the method 100.

[0088] In some possible implementation manners, if the network system does not include a control and management device, then the indication information of the first SID list can be generated by the PE device 11 or the PE device 12.

[0089] In one case, the indication information of the first SID list can be generated by the PE device 11. Then, the PE device 11 can also send the indication information of the first SID list to the PE device 12, so that the PE device 12 can determine a forwarding path that is reverse common with the forwarding path 41 for the response message C corresponding to the BFD message c based on the indication information of the first SID list. In another case, the indication information of the first SID list can also be generated by the PE device 12. Then, the PE device 12 can send the indication information of the first SID list to the PE device 11, so that the PE device 11 can carry the indication information of the first SID list in the sent BFD message c to ensure the effective BFD detection of the forwarding path 41.

[0090] As an example, the indication information of the first SID list is the BSID corresponding to the forwarding path 41. Both the PE device 11 and the PE device 12 can obtain the indication information corresponding to the first SID list: BSID 410. In this way, the PE device 12 can save the mapping relationship between the BSID 410 and the forwarding path 42; or, the PE device 12 can also save the mapping relationship between the BSID 410 and the BSID 420 corresponding to the forwarding path 42, and the mapping relationship between the BSID 420 and the forwarding path 42, so as to ensure that the PE device 12 can determine the forwarding path 42 based on the indication information of the first SID list in the BFD message c. Among them, the BSID420 can be the indication information of the SID list corresponding to the forwarding path 42, and can be allocated by the PE device 11 or the PE device 12 for the forwarding path 42.

[0091] As another example, the indication information of the first SID list can also be used to indicate the SID list corresponding to the forwarding path 42. In one case, the indication information of the first SID list can be generated by the PE device 12. Then, the PE device 12 can send the indication information of the first SID list to the PE device 11, so that the PE device 11 can carry the indication information of the first SID list in the sent BFD packet c to ensure the effective BFD detection of the forwarding path 41. In another case, the indication information of the first SID list can also be generated by the PE device 11. Then, the PE device 11 can also send the indication information of the first SID list to the PE device 12, so that the PE device 12 can determine a forwarding path that is reverse common with the forwarding path 41 for the response packet C corresponding to the BFD packet c based on the indication information of the first SID list. Taking the indication information of the first SID list as the Path Segment corresponding to the forwarding path 42 as an example, both the PE device 11 and the PE device 12 can obtain the indication information corresponding to the first SID list: Path Segment 420. In this way, the PE device 12 can determine the forwarding path 42 based on the indication information of the first SID list in the BFD packet c.

[0092] It should be noted that the PE11 or PE12 can also generate the indication information of the second SID list. If the indication information of the first SID list is used to indicate the SID list corresponding to the forwarding path 41, then the indication information of the second SID list can be used to indicate the SID list corresponding to the forwarding path 42; if the indication information of the first SID list is used to indicate the SID list corresponding to the forwarding path 42, then the indication information of the second SID list can be used to indicate the SID list corresponding to the forwarding path 41.

[0093] In some other possible implementation manners, if the network system includes a control and management device, then the indication information of the first SID list can be sent by the control and management device to the PE device 11 and the PE device 12.

[0094] As an example, the control and management device may generate indication information of the first SID list and send the indication information of the first SID list to PE device 11 and PE device 12. For example, the control and management device sends message 51 to PE device 11 or PE device 12, and the indication information of the first SID list is carried in the message 51. In this way, the PE device that receives the indication information of the first SID list from the control and management device can also forward the indication information of the first SID list to the other end PE device in the SR policy 1. As another example, the control and management device sends message 52 to PE device 11 and PE device 12, and the indication information of the first SID list is carried in the message 52.

[0095] As another example, PE device 11 or PE device 12 may also generate indication information of the first SID list, send the indication information of the first SID list to the control and management device, and the control and management device sends the indication information of the first SID list to PE device 11 and PE device 12. For example, PE device 11 or PE device 12 sends message 61 to the control and management device, and the indication information of the first SID list is carried in the message 61. After receiving the message 61, the control and management device obtains the indication information of the first SID list from the message 61 and sends message 53 to PE device 11 and PE device 12, and the indication information of the first SID list is carried in the message 53. Before the control and management device receives message 61, it may also send the relevant information of SR policy 1 and SR policy 3 to PE device 11 and PE device 12, and instruct PE device 11 or PE device 12 to allocate the corresponding indication information of the SID list (including the above indication information of the first SID list) for each forwarding path in the SR policy 1 and SR policy 3, and carry it in the message 61 and send it to the control and management device.

[0096] In the above two examples, in message 51, message 52, message 53 or message 61, the indication information of the second SID list may also be included, where the indication information of the second SID list may be used to indicate forwarding path 41, and the indication information of the first SID list is used to indicate forwarding path 42; or, the indication information of the second SID list may also be used to indicate forwarding path 42, and the indication information of the first SID list indicates forwarding path 41.

[0097] Among them, the message 51, the message 52, and the message 53 can be, for example, border gateway protocol segment routing policy (BGPSR policy) packets, and the BGPSR policy packet can carry the indication information of the first SID list through an extended sub type length value (sub-TLV) field. As Figure 4a shown, the sub-TLV field for carrying the indication information of the first SID list in the BGPSR policy packet may include: a Type field, a Length field, a Reserved field, and a Value field. Among them, the value of the Type field is used to indicate that the sub-TLV field carries the indication information of the first SID list, the value of the Length field is used to indicate the length of the Value field in the sub-TLV field, and the value of the Value field includes the indication information of the first SID list. If the BGPSR policy packet also carries the indication information of the second SID list, then, in one case, the indication information of the first SID list and the indication information of the second SID list can be carried in the same sub-TLV field, and the format of the sub-TLV field is as Figure 4bAs shown, in addition to including a Type field, a Length field, a Reserved field, and a Value field, it may also include a Flags field. The value of the Flags field is used to indicate the number of indication messages of the SID list carried in this sub-TLV field and the forwarding path indicated by the indication messages of the SID list. For example, the value of one bit of the Flags field is used to indicate that the Value field of this sub-TLV field includes the indication information of the first SID list, and the value of another bit of the Flags field is used to indicate that the Value field of this sub-TLV field includes the indication information of the second SID list. The Value field of this sub-TLV field includes the indication information of the first SID list and the indication information of the second SID list. In another case, the indication information of the first SID list and the indication information of the second SID list can be carried in two sub-TLV fields of the BGPSR policy message respectively. The format of each sub-TLV field can refer to 4a. The Value field of the sub-TLV field for carrying the indication information of the first SID list includes the indication information of the first SID list, and the Value field of the sub-TLV field for carrying the indication information of the second SID list includes the indication information of the second SID list. Taking the indication information of the SID list as the BSID as an example, if the SR policy is an SRv6 policy, then, Figure 4a or Figure 4b the value of the Value field is an IPv6 address; if the SR policy is an SR-MPLS policy, then, Figure 4a or Figure 4b the value of the Value field is an MPLS label. The format of the Value field can refer to Figure 4c shown, including a Label field, a Traffic Class (Exp (also known as TC)) field, a Flags bit (S), and a Time to Live (TTL) field. Among them, the TC field, the S bit, and the TTL field are reserved fields and can be set to 0.

[0098] Message 61 can be, for example, a Border Gateway Protocol Link State (BGP-LS) message. This BGP-LS message can use a sub-TLV field in the SID list TLV field defined by the BGP-LS protocol to carry the indication information of the first SID list. Among them, the format of the SID list TLV field defined by the BGP-LS protocol in the BGP-LS message is as Figure 5aAs shown in the figure, the SID list TLV field may include: a Type field, a Length field, a Flags field, a Reserved field, a Message Type Identifier (MT ID) field, an Algorithm field, a Reserved field, a Weight field, and at least one variable-length sub-TLV field. As Figure 5b As shown in the figure, the sub-TLV field in the BGP-LS message for carrying the indication information of the first SID list may include: a Type field, a Length field, and a Value field. Among them, the value of the Type field is used to indicate that the sub-TLV field carries the indication information of the first SID list, the value of the Length field is used to indicate the length of the Value field in the sub-TLV field, and the value of the Value field includes the indication information of the first SID list. If the BGP-LS message also carries the indication information of the second SID list, then, in one case, the indication information of the first SID list and the indication information of the second SID list may be carried in one sub-TLV field, and the format of this sub-TLV field is as Figure 5c As shown in the figure, in addition to including: a Type field, a Length field, and a Value field, it may also include a Flags field. The value of the Flags field is used to indicate the number of SID list indication information carried in the sub-TLV field and the forwarding paths indicated by the indication information of each SID list. For example, the value of the first bit of the Flags field is used to indicate that the Value field of the sub-TLV field includes the indication information of the first SID list, the value of the second bit of the Flags field is used to indicate that the Value field of the sub-TLV field includes the indication information of the second SID list, and the Value field of the sub-TLV field includes the indication information of the first SID list and the indication information of the second SID list. In another case, the indication information of the first SID list and the indication information of the second SID list may be carried in two sub-TLV fields of the BGP-LS message respectively. The format of each sub-TLV field may refer to 5b. The Value field of the sub-TLV field for carrying the indication information of the first SID list includes the indication information of the first SID list, and the Value field of the sub-TLV field for carrying the indication information of the second SID list includes the indication information of the second SID list. Taking the indication information of the SID list as the BSID as an example, if the SR policy is an SRv6 policy, then, Figure 5b orFigure 5c The value of the Value field is an IPv6 address; if the SR policy is an SR-MPLS policy, then, Figure 5b or Figure 5c the value of the Value field is an MPLS label, and the format of the Value field can be referred to Figure 4c as shown.

[0099] Suppose that the indication information of the first SID list and the indication information of the second SID list are included in Message 51, Message 52, Message 53, and Message 61. In one case, if the indication information of the first SID list and the indication information of the second SID list in Message 51, Message 52, or Message 53 are carried in a sub-TLV field, then, the indication information of the first SID list and the indication information of the second SID list in Message 61 can also be carried in a sub-TLV field; in another case, if the indication information of the first SID list and the indication information of the second SID list in Message 51, Message 52, or Message 53 are carried in two sub-TLV fields, then, the indication information of the first SID list and the indication information of the second SID list in Message 61 can also be carried in two sub-TLV fields.

[0100] In addition, Message 51, Message 52, Message 53, and Message 61 can also be network configuration protocol (NETCONF) or path computation element protocol (PCEP) packets for carrying the indication information of the first SID list, and the specific implementation is not elaborated in the embodiments of the present application.

[0101] It should be noted that when the PE device 11 and the PE device 12 interact with the indication information of the first SID list, the indication information of the first SID list to be interacted can be carried in a BGP packet. For example, the indication information of the first SID list can be carried through a TLV field or a sub-TLV field in the BGP packet.

[0102] In the embodiments of the present application, the indication information of the SID list may be the BSID corresponding to the SID list. This BSID is different from the BSID assigned to the candidate path in the current SR policy. The BSID corresponding to the candidate path is used to indicate the candidate path but cannot identify the specific forwarding path under the candidate path, and can be called the BSID corresponding to the candidate path as the Path BSID (abbreviation: P-BSID); the BSID corresponding to the forwarding path in the present application is used to indicate the specific forwarding path, and can be called the BSID at the SID list level (abbreviation: L-BSID). The BSID used to indicate the forwarding path in the context of the embodiments of the present application mainly refers to the L-BSID. The above explanation is mainly used to illustrate that the BSID required for the present application to implement reverse common path detection is at the SID list level, but it does not mean that the contents of the P-BSID and the L-BSID cannot be the same in the same SR policy. For example, at least for the case where the candidate path of the SR policy only includes one SR list, the values of the P-BSID and the L-BSID can be the same. In this case, the indication information of the SID list can even be interpreted as the BSID corresponding to the candidate path.

[0103] For example, when the control and management device sends the indication information of the first SID list to the PE device 11 and the PE device 12, and the indication information of the first SID list is the L-BSID, the operations that need to be performed before S101 may include: S41, the control and management device establishes the SR policy 1 and the SR policy 2 from the PE device 11 to the PE device 12, and the SR policy 3 and the SR policy 4 from the PE device 12 to the PE device 11;

[0104] S42, the control and management device assigns the L-BSID to the forwarding paths in each SR policy, for example, including:

[0105] For the direction from the PE device 11 to the PE device 12, the configuration is as follows:

[0106] The primary SR policy is SR policy 1. SR policy 1 includes the forwarding path 41. The SID list of the forwarding path 41 is <41021, 41022, 41012>, and the L-BSID corresponding to the forwarding path 41 is 410;

[0107] The backup SR policy is SR policy 2. SR policy 2 includes the forwarding path 43. The SID list of the forwarding path 43 is <43023, 43024, 43012>, and the L-BSID corresponding to the forwarding path 43 is 430;

[0108] For the direction from PE device 12 to PE device 11, the configuration is as follows:

[0109] The primary SR policy is SR policy 3. SR policy 3 includes forwarding path 42. The SID list of forwarding path 42 is <42022, 42021, 42011>, and the L-BSID corresponding to forwarding path 42 is 420;

[0110] The standby SR policy is SR policy 4. SR policy 4 includes forwarding path 44. The SID list of forwarding path 44 is <44024, 44023, 44011>, and the L-BSID corresponding to forwarding path 44 is 440.

[0111] S43, the control and management device sends the relevant configurations of SR policy 1 and SR policy 2 to PE device 11, and sends the L-BSID of forwarding path 42 that is reverse common path with forwarding path 41 in SR policy 1, and the L-BSID of forwarding path 44 that is reverse common path with forwarding path 43 in SR policy 2; the control and management device sends the relevant configurations of SR policy3 and SR policy 4 to PE device 12, and sends the L-BSID of forwarding path 41 that is reverse common path with forwarding path 42 in SR policy 3, and the L-BSID of forwarding path 42 that is reverse common path with forwarding path 44 in SR policy 4. Specifically, it includes:

[0112] The content sent by the control and management device to PE device 11 is as follows:

[0113] The SID list of forwarding path 41 in the primary SR policy 1 is <41021, 41022, 41012>, the L-BSID corresponding to forwarding path 41 is 410, and the L-BSID of the reverse common path forwarding path 42 is 420;

[0114] The SID list of forwarding path 43 in the standby SR policy 2 is <43023, 43024, 43012>, the L-BSID corresponding to forwarding path 43 is 430, and the L-BSID of the reverse common path forwarding path 44 is 440;

[0115] The content sent by the control and management device to PE device 12 is as follows:

[0116] The SID list of the forwarding path 42 in the primary SR policy 3 is <42022, 42021, 42011>, the L-BSID corresponding to the forwarding path 42 is 420, and the L-BSID corresponding to the reverse common path forwarding path 41 is 410;

[0117] The SID list of the forwarding path 44 in the standby SR policy 4 is <44024, 44023, 44011>, the L-BSID corresponding to the forwarding path 44 is 440, and the L-BSID corresponding to the reverse common path forwarding path 43 is 430.

[0118] In this way, the indication information of the first SID list is configured, the indication information of the first SID list is carried in the BFD packet c, and the BFD packet c is sent to the PE device 12 through the forwarding path 41 in the SR policy 1, and the PE device 11 initiates a fault detection for the forwarding path 41 in the SR policy 1. Similarly, the method provided in the embodiments of the present application is also applicable to the PE device 11 to perform fault detection on other forwarding paths included in the SR policy 1, and the implementation manner is the same as the fault detection manner for the forwarding path 41, which will not be elaborated here.

[0119] The control and management device in the embodiments of the present application can be any device capable of controlling and managing devices in a network system. For example, it can be a software defined network (SDN) controller.

[0120] S103, the PE device 12 determines the forwarding path 42 according to the indication information of the first SID list, and the forwarding path 42 and the forwarding path 41 are reverse common paths.

[0121] Among them, the indication information of the first SID list is used to instruct the PE device 12 to determine the forwarding path 42 for sending the response packet C of the BFD packet c, and the forwarding path 42 and the forwarding path 41 are reverse common paths.

[0122] Specifically, when the PE device 12 receives the BFD packet c sent by the PE device 11 through the forwarding path 41, the PE device 12 obtains the indication information of the first SID list by parsing the BFD packet c. Thus, the PE device 12 can determine the forwarding path 42 that is reverse to the forwarding path 41 based on the indication information of the first SID list, preparing for the BFD packet c and the response packet C to be transmitted through the reverse common path forwarding path to complete accurate fault detection.

[0123] As an example, if the indication information of the first SID list is used to indicate the SID list corresponding to the forwarding path 42, then in S103, the PE device 12 can directly determine the forwarding path 42 according to the indication information of the first SID list.

[0124] As another example, if the indication information of the first SID list is used to indicate the SID list corresponding to the forwarding path 41, then in one case, assuming that the mapping relationship between the indication information of the first SID list and the indication information of the second SID list is saved on the PE device 12, and the indication information of the second SID list is used to indicate the SID list corresponding to the forwarding path 42, then S103 may include, for example: the PE device 12 determines the indication information of the second SID list according to the indication information of the first SID list; then, the PE device 12 determines the forwarding path 42 according to the indication information of the second SID list. In another case, assuming that the mapping relationship between the indication information of the first SID list and the forwarding path 42 is saved on the PE device 12, then in S103, the PE device 12 can also directly determine the forwarding path 42 according to the indication information of the first SID list.

[0125] S104, the PE device 12 sends the response message C of the BFD message c to the PE device 11 through the forwarding path 42, and the response message C is used to instruct the PE device 11 to perform a fault detection on the forwarding path 41.

[0126] In some possible situations, if there is a fault in the network device or link through which the forwarding path 42 passes when S104 is executed, or if there is a fault in the network device or link through which the forwarding path 41 passes before S104, then the PE device 11 may not be able to receive the response message C. Then, if the PE device 11 does not receive the response message C through the forwarding path 42 within a preset time (such as 1 second), since the forwarding path 41 and the forwarding path 42 are reverse common paths, it can be determined that the forwarding path 41 has a fault.

[0127] In some other possible situations, if the network devices and links through which the forwarding path 42 passes are all normal when S104 is executed, then the embodiments of the present application may further include the following S105 to S106 to determine that the forwarding path 41 has no fault.

[0128] S105, the PE device 11 receives the response message C of the BFD message c from the forwarding path 42.

[0129] S106, the PE device 11 performs a fault detection on the forwarding path 41 according to the response message C.

[0130] In specific implementation, S106 may refer to: Based on the received response message C, PE device 11 determines that both the forwarding path 41 for transmitting BFD message c and the forwarding path 42 for transmitting the response message C are normal. Since the forwarding path 41 and the forwarding path 42 are reverse common paths, it is determined that there is no fault in the forwarding path 41.

[0131] It can be seen that through this method 100, the transmitting end of BFD detection carries the indication information of the SID list in the BFD message, enabling the receiving end to determine, based on the indication information of the SID list, the forwarding path that is reverse common with the forwarding path for transmitting the BFD message, and sending the response message of the BFD message to the transmitting end based on the determined forwarding path. By ensuring that the actual forwarding paths of the BFD message and the response message are reverse common paths, accurate fault detection of the specific forwarding path in the SR policy is achieved, improving the accuracy and precision of the BFD mechanism for fault detection of the SR policy.

[0132] In some possible implementation manners, considering that an SR policy with a bidirectional common path is established. For example, the control and management device can create SR Policy 1 and SR policy 3 with bidirectional common paths, and associate the forward forwarding path and the reverse forwarding path of SR Policy 1 and SR policy 3. Thus, the BFD mechanism can be used to achieve bidirectional fault detection. Only the fault detection of the forwarding path 41 in SR policy 1 by PE device 11 is introduced in the above method 100. Similarly, the embodiment of the present application may further include the following method 200 to implement the fault detection of the forwarding path 42 in SR policy 3 by PE device 12, where the forwarding path 42 and the forwarding path 41 are reverse common paths. In specific implementation, the method 200 may include, for example:

[0133] S201, PE device 12 sends a BFD message d to PE device 11 through the forwarding path 42 of SR policy 3, and the BFD message d includes the indication information of the third SID list.

[0134] S202, PE device 11 receives the BFD message d sent by PE device 12 through the forwarding path 42 of SR policy 3, and the BFD message d includes the indication information of the third SID list.

[0135] S203, PE device 11 determines the forwarding path 41 according to the indication information of the third SID list, and the forwarding path 42 and the forwarding path 41 are reverse common paths.

[0136] The indication information of the third SID list is used to instruct the PE device 11 to determine the forwarding path 41 of the response message D for the BFD message d, and the forwarding path 41 and the forwarding path 42 are reverse common paths.

[0137] S204. The PE device 11 sends the response message D of the BFD message d to the PE device 12 through the forwarding path 41.

[0138] In some possible situations, if there is a fault in the network device or link through which the forwarding path 41 passes when S204 is executed, or if there is a fault in the network device or link through which the forwarding path 42 passes before S204, then the PE device 12 may not receive the response message D. Then, since the PE device 12 does not receive the response message D, it can determine that the forwarding path 42 is faulty.

[0139] In some other possible situations, if the network devices and links through which the forwarding path 41 passes are all normal when S204 is executed, then, optionally, the embodiments of the present application may further include the following S205 to S206:

[0140] S205. The PE device 12 receives the response message D from the forwarding path 41.

[0141] S206. The PE device 12 performs a fault detection on the forwarding path 42 according to the response message D.

[0142] The PE device 12 determines that both the forwarding path 42 and the forwarding path 41 for transmitting the BFD message d and the response message D are normal according to the received response message D, so it determines that the forwarding path 42 has no fault.

[0143] For the specific implementation manners and achieved effects of the above S201 to S206, reference may be made to the relevant descriptions in the method 100, which will not be elaborated here.

[0144] The method 200 can be implemented independently or implemented as a whole with the method 100. If the method 100 and the method 200 are implemented as a whole, then no specific limitation is imposed on the execution sequence of the two.

[0145] In some possible implementations, there is more than one SR policy from PE device 11 to PE device 12. For example, to improve the reliability of the network system, an SR policy 2 from PE device 11 to PE device 12 can also be constructed as a backup tunnel for SR policy 1. For example, the control and management device creates SR policy 1 and SR policy 2, and creates SR policy 3 and SR policy 4 with reverse common paths for both. After the deployment, BFD detection is performed on both the primary and backup SR policies according to the method provided in the embodiments of this application. The embodiments of this application can also include the following method 300 to implement fault detection for the forwarding path in other SR policies from PE device 11 to PE device 12. For example, PE device 11 can perform fault detection on the forwarding path 43 in SR policy 2. Specifically, the method 300 can include, for example:

[0146] S301, PE device 11 sends a BFD packet e to PE device 12 through the forwarding path 43 of SR policy 2, and the BFD packet e includes indication information of a fourth SID list.

[0147] S302, PE device 12 receives the BFD packet e sent by PE device 11 through the forwarding path 43 of SR policy 2, and the BFD packet e includes indication information of a fourth SID list.

[0148] S303, PE device 12 determines a forwarding path 44 according to the indication information of the fourth SID list, and the forwarding path 44 and the forwarding path 43 have a reverse common path.

[0149] The indication information of the fourth SID list is used to instruct PE device 12 to determine the forwarding path 44 for sending the response packet E of the BFD packet e, and the forwarding path 44 and the forwarding path 43 have a reverse common path.

[0150] S304, PE device 12 sends the response packet E of the BFD packet e to PE device 11 through the forwarding path 44.

[0151] In some possible situations, if there is a fault in the network device or link through which the forwarding path 44 passes when S304 is executed, or if there is a fault in the network device or link through which the forwarding path 43 passes before S304, then PE device 11 may not be able to receive the response packet E. Then, since PE device 11 does not receive the response packet E, it can determine that the forwarding path 43 is faulty.

[0152] In some other possible situations, if all the network devices and links through which the forwarding path 44 passes are normal when S304 is executed, then, optionally, the embodiments of the present application may further include the following S305 to S306:

[0153] S305, the PE device 11 receives the response message E of the BFD message e from the forwarding path 44.

[0154] S306, the PE device 11 performs a fault detection on the forwarding path 43 according to the response message E.

[0155] Based on the received response message E, the PE device 11 determines that both the forwarding path 43 for transmitting the BFD message e and the response message E and the forwarding path 44 are normal. Therefore, it is determined that there is no fault in the forwarding path 43.

[0156] For the specific implementation manners and achieved effects of the above S301 to S306, reference may be made to the relevant descriptions in the method 100, which will not be elaborated here.

[0157] The method 300 may be implemented independently, or may be implemented as a whole with the method 100, or may be implemented as a whole with the method 200, or may also be implemented as a whole with the method 100 and the method 200. If the method 300 and the method are implemented as a whole, no specific limitation is imposed on the execution sequence.

[0158] Next, taking the scenario of SR-MPLS policy as an example, where the control and management device sends the indication information of the first SID list to the PE device 11 and the PE device 12, and the indication information of the first SID list is L-BSID, an exemplary description is given of the formats of the BFD message and the response message corresponding to the BFD message in the above methods.

[0159] Among them, the format of the BFD message c can be referred to Figure 6a , and the BFD message c may include an MPLS label stack and a payload. Among them, the MPLS label stack may include: the SID list corresponding to the forwarding path 41: 41021, 41022, and 41012, and the indication information L-BSID 420 of the first SID list. The response message C may include an MPLS label stack and a payload. Among them, the MPLS label stack may include: the SID list corresponding to the forwarding path 42: 42022, 42021, and 42011.

[0160] The format of the BFD message d can be referred to Figure 6b, the BFD packet d may include an MPLS label stack and a payload. Among them, the MPLS label stack may include: the SID list corresponding to the forwarding path 42: 42022, 42021, and 42011, and the indication information L-BSID 410 of the third SID list. The response packet C may include an MPLS label stack and a payload. Among them, the MPLS label stack may include the SID list corresponding to the forwarding path 41: 41021, 41022, and 41012.

[0161] The format of the BFD packet e can be referred to Figure 6c , the BFD packet c may include an MPLS label stack and a payload. Among them, the MPLS label stack may include: the SID list corresponding to the forwarding path 43: 43023, 43024, and 43012, and the indication information L-BSID 440 of the fourth SID list. The response packet C may include an MPLS label stack and a payload. Among them, the MPLS label stack may include: the SID list corresponding to the forwarding path 44: 44024, 44023, and 44011.

[0162] In the above BFD packet c, BFD packet d, BFD packet e, response packet C, response packet D, and response packet E, the payload may include Internet Protocol (IP), User Datagram Protocol (UDP), and detection information. Among them, the detection information is BFD information.

[0163] It should be noted that the SID list included in the MPLS label stack in the BFD packet and the response packet may be the MPLS labels corresponding to each hop from the next-hop device to the egress PE device, as shown above Figures 6a - 6c ; or, the SID list included in the MPLS label stack in the BFD packet and the response packet may also be the SID list obtained after stripping the MPLS label corresponding to the next-hop device after determining the next-hop at the ingress PE device. For example, Figure 6a the MPLS label stack of the BFD packet c in

[0164] It should be noted that the above Figures 6a - 6cTaking the SR-MPLS policy scenario as an example, the message format is described. If in the SRv6 policy scenario, the indication information carrying the SID list is the segment routing header (SRH) in the message, and the indication information of the SID list carried in the SRH and the SID list corresponding to the forwarding path can be IPv6 addresses. In addition, although the embodiments of the present application mainly describe the scenario where the SR policy is used as a tunnel implementation technology, this reverse common path detection method can obviously be applied to other possible tunnel implementation technologies that can specify the forwarding path in some way. Therefore, the embodiments of the present application also provide a fault detection method. In this method, the first network device receives a first detection message sent by the second network device through the first forwarding path of the first tunnel, and the first detection message includes the indication information of the first forwarding path; the first network device determines a second forwarding path according to the indication information of the first forwarding path, and the second forwarding path and the first forwarding path are reverse common paths; the first network device sends a first response message of the first detection message to the second network device through the second forwarding path, and the first response message is used to instruct the second network device to detect the first forwarding path. The detection message can be a detection message for implementing path fault detection, such as a BFD message or other fault detection messages, or other types of detection messages, such as operation, administration and maintenance (OAM) messages, etc.

[0165] Based on the above method embodiments, the embodiments of the present application provide a fault detection device, which will be described below with reference to the accompanying drawings.

[0166] Figure 7 It is a schematic structural diagram of a fault detection device 700 provided by the embodiments of the present application. The device 700 is applied to the first network device and can, for example, execute Figure 1 the functions of the PE device 12 in the illustrated embodiment. The device 700 may include: a receiving unit 701, a determining unit 702, and a sending unit 703.

[0167] Among them, the receiving unit 701 is configured to receive a first BFD message sent by the second network device through the first forwarding path of the first SR policy, and the first BFD message includes the indication information of the first segment identifier list SID list.

[0168] When the device 700 is applied to Figure 1When the device 700 is applied to the PE device 12 as shown, for the specific implementation of the receiving unit 701 receiving the first BFD packet sent by the second network device through the first forwarding path of the first SR policy, reference can be made to Figure 3 S101 and S102 in the above embodiments.

[0169] A determining unit 702, configured to determine a second forwarding path according to the indication information of the first SID list, where the second forwarding path and the first forwarding path are reverse common paths.

[0170] When the device 700 is applied to Figure 1 the PE device 12 as shown, for the specific implementation of the determining unit 702 determining the second forwarding path according to the indication information of the first SID list, reference can be made to Figure 3 S103 in the above embodiments.

[0171] A sending unit 703, configured to send a first response packet of the first BFD packet to the second network device through the second forwarding path, where the first response packet is used to instruct the second network device to perform a fault detection on the first forwarding path.

[0172] When the device 700 is applied to Figure 1 the PE device 12 as shown, for the specific implementation of the sending unit 703 sending the first response packet of the first BFD packet to the second network device through the second forwarding path, reference can be made to Figure 3 S104 in the above embodiments.

[0173] In a possible implementation manner, the device 700 may further include a generating unit. Wherein, the generating unit is configured to generate the indication information of the first SID list before receiving the first BFD packet sent by the second network device through the first forwarding path of the first SR policy.

[0174] In a possible implementation manner, the receiving unit 701 is further configured to receive the indication information of the first SID list sent by the second network device.

[0175] In a possible implementation, the receiving unit 701 is further configured to receive a message sent by a control and management device, where the message includes indication information of the first SID list. As an example, the message further includes indication information of a second SID list, where the indication information of the second SID list indicates the first forwarding path, and the indication information of the first SID list indicates the second forwarding path; or, the indication information of the second SID list indicates the second forwarding path, and the indication information of the first SID list indicates the first forwarding path. Wherein, the above message may be, for example, a BGPSR policy message, and the BGPSR policy message carries the indication information of the first SID list through a sub-TLV field.

[0176] As an example, the indication information of the first SID list is used to indicate the SID list corresponding to the second forwarding path.

[0177] As another example, the indication information of the first SID list is used to indicate the SID list corresponding to the first forwarding path, and the determining unit 702 is specifically configured to: determine the indication information of the second SID list according to the indication information of the first SID list; and determine the second forwarding path according to the indication information of the second SID list.

[0178] In a possible implementation, the sending unit 703 is further configured to send a second BFD message to the second network device through the second forwarding path of the second SR policy, where the second BFD message includes indication information of a third SID list, and the indication information of the third SID list is used to indicate the first forwarding path for the first network device to determine to send a second response message to the second BFD message; the receiving unit 701 is further configured to receive the second response message from the first forwarding path; then, the apparatus 700 further includes a detection unit, and the detection unit is configured to perform a fault detection on the second forwarding path according to the second response message.

[0179] In a possible implementation, the receiving unit 701 is further configured to receive a third BFD message sent by the second network device through a third forwarding path of the first SR policy. The third BFD message includes indication information of a fourth SID list, and the third forwarding path is different from the first forwarding path. The determining unit 702 is further configured to determine a fourth forwarding path according to the indication information of the fourth SID list, and the fourth forwarding path is reverse common path with the third forwarding path. The sending unit 703 is further configured to send a third response message of the third BFD message to the second network device through the fourth forwarding path, and the third response message is used to instruct the second network device to perform a fault detection on the third forwarding path.

[0180] Wherein, the indication information of the first SID list may be a Path Segment or a BSID; or, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a Path Segment or a BSID or the second SID list itself.

[0181] Regarding the specific functions and implementations that the fault detection device 700 can perform, reference can be made to Figure 3 the corresponding description of the PE device 12 in the illustrated embodiment, which will not be elaborated here.

[0182] In addition, an embodiment of the present application further provides a fault detection device 800, as Figure 8 shown. This device 800 is applied to the second network device and can perform, for example, Figure 1 the functions of the PE device 11 in the illustrated embodiment. This device 800 may include: a sending unit 801, a receiving unit 802, and a detecting unit 803.

[0183] Wherein, the sending unit 801 is configured to send a BFD message to the first network device through a first forwarding path of the first SR policy. The BFD message includes indication information of a first SID list, and the indication information of the first SID list is used to instruct the first network device to determine a second forwarding path for sending a response message of the BFD message, and the second forwarding path is reverse common path with the first forwarding path.

[0184] When the device 800 is applied to Figure 1 the PE device 11 shown, the specific implementation of the sending unit 801 sending a BFD message to the first network device through the first forwarding path of the first SR policy can be referred to Figure 3 S101 in the said embodiment.

[0185] A receiving unit 802, configured to receive a response message of the BFD message from the second forwarding path.

[0186] When the device 800 is applied to Figure 1 the PE device 11 shown in the figure, for the specific implementation of the receiving unit 802 to receive the response message of the BFD message from the second forwarding path, reference may be made to Figure 3 S104 and S105 in the embodiment.

[0187] A detecting unit 803, configured to perform a fault detection on the first forwarding path according to the response message.

[0188] When the device 800 is applied to Figure 1 the PE device 11 shown in the figure, for the specific implementation of the detecting unit 803 to perform a fault detection on the first forwarding path according to the response message, reference may be made to Figure 3 S106 in the embodiment.

[0189] In a possible implementation manner, the receiving unit 802 is further configured to receive indication information of the first SID list sent by the first network device before sending a BFD message to the first network device through the first forwarding path of the first SR policy.

[0190] In a possible implementation manner, the receiving unit 802 is further configured to receive indication information of the first SID list sent by a control and management device before sending a BFD message to the first network device through the first forwarding path of the first SR policy. As an example, the receiving unit 802 is specifically configured to: receive a BGP SR policy message sent by the control and management device, and the BGP SR policy message carries the indication information of the SID list through a sub-TLV field. In this implementation manner, the sending unit 801 is further configured to send the indication information of the first SID list to the control and management device before receiving the indication information of the first SID list sent by the control and management device. Among them, the sending unit 801 is specifically configured to: send a BGP-LS message to the control and management device, and the BGP-LS message carries the indication information of the first SID list through a sub-TLV field.

[0191] In a possible implementation manner, the device 800 further includes a generating unit, and the generating unit is configured to generate the indication information of the first SID list. Then, the sending unit 801 is further configured to send the indication information of the SID list to the first network device.

[0192] Among them, the indication information of the first SID list may be a Path Segment or a BSID; alternatively, the indication information of the first SID list may also be the first SID list itself. Similarly, the indication information of the second SID list may also be a Path Segment or a BSID or the second SID list itself.

[0193] Regarding the specific functions and implementations that the fault detection device 800 can perform, reference can be made to Figure 3 the corresponding description of the PE device 11 in the illustrated embodiment, which will not be elaborated here.

[0194] Figure 9 FIG. is a schematic structural diagram of a network device 900 provided by an embodiment of the present application. The network device 900 may be, for example, Figure 1 any one of the PE devices in the illustrated embodiment, or may also be Figure 7 or Figure 8 the device implementation of the fault detection device in the illustrated embodiment.

[0195] Please refer to Figure 9 shown in the figure, the network device 900 includes: a processor 910, a communication interface 920, and a memory 930. Among them, the number of processors 910 in the network device 900 may be one or more. Figure 9 Taking one processor as an example. In the embodiment of the present application, the processor 910, the communication interface 920, and the memory 930 may be connected through a bus system or other means. Among them, Figure 9 taking the connection through the bus system 940 as an example.

[0196] The processor 910 may be a CPU, an NP, or a combination of a CPU and an NP. The processor 910 may further include a hardware chip. The above hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The above PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0197] When the network device 900 includes a first network device, the processor 910 may perform related functions such as determining a second forwarding path according to the indication information of the first SID list in the above method embodiments. When the network device 900 is a second network device, the processor 910 may perform related functions such as performing a fault detection on the first forwarding path according to the response message in the above method embodiments.

[0198] The communication interface 920 is used to receive and send messages. Specifically, the communication interface 920 may include a receiving interface and a sending interface. Among them, the receiving interface may be used to receive messages, and the sending interface may be used to send messages. The number of communication interfaces 920 may be one or more. As a possible implementation, the communication interface 920 may be used to implement Figure 7 the sending unit 703 shown in Figure 8 or the function of the receiving unit 802 shown in

[0199] The memory 930 may include a volatile memory (English: volatile memory), such as a random-access memory (random-access memory, RAM); the memory 930 may also include a non-volatile memory (English: non-volatile memory), such as a flash memory (English: flash memory), a hard disk (hard disk drive, HDD) or a solid-state drive (solid-state drive, SSD); the memory 930 may further include a combination of the above types of memories. The memory 930 may store, for example, the indication information of the first SID list mentioned above.

[0200] Optionally, the memory 930 stores an operating system and programs, executable modules or data structures, or subsets thereof, or extended sets thereof, where the programs may include various operation instructions for implementing various operations. The operating system may include various system programs for implementing various basic services and processing hardware-based tasks. The processor 910 may read the programs in the memory 930 to implement the method for fault detection provided in the embodiments of the present application. As a possible implementation, the memory 930 may store, for example, programs for implementing Figure 7 the determining unit 702 shown in Figure 8 or the program code for the function of the detecting unit 803 shown in

[0201] Among them, the memory 930 may be a storage device in the network device 900 or a storage device independent of the network device 900.

[0202] The bus system 940 can be a peripheral component interconnect (PCI) bus, an extended industry standard architecture (EISA) bus, or the like. The bus system 940 can be divided into an address bus, a data bus, a control bus, etc. For the sake of convenience of representation, Figure 9 only a thick line is used to represent it in Figure 9 , but it does not mean that there is only one bus or one type of bus.

[0203] Figure 10 FIG. is a schematic structural diagram of another network device 1000 provided by an embodiment of the present application. The network device 1000 can be configured as any one of the PE devices in the foregoing Figure 1 illustrated embodiments, or it can also be Figure 7 or Figure 8 the device implementation of the fault detection device in the illustrated embodiments.

[0204] The network device 1000 includes: a main control board 1010 and an interface board 1030.

[0205] The main control board 1010 is also called a main processing unit (MPU) or a route processor card. The main control board 1010 controls and manages each component in the network device 1000, including routing calculation, device management, device maintenance, and protocol processing functions. The main control board 1010 includes: a central processing unit 1011 and a memory 1012.

[0206] The interface board 1030 is also called a line processing unit (LPU) card, a linecard, or a service board. The interface board 1030 is used to provide various service interfaces and implement packet forwarding. The service interfaces include but are not limited to Ethernet interfaces, POS (Packet over SONET / SDH) interfaces, etc. The Ethernet interface is, for example, a Flexible Ethernet Clients (FlexE Clients). The interface board 1030 includes: a central processing unit 1031, a network processor 1032, a forwarding table entry memory 1034, and a physical interface card (PIC) 1033.

[0207] The central processing unit 1031 on the interface board 1030 is used to control and manage the interface board 1030 and communicate with the central processing unit 1011 on the main control board 1010.

[0208] The network processor 1032 is used to implement the forwarding process of packets. The form of the network processor 832 can be a forwarding chip. Specifically, the processing of upstream packets includes: the processing of the packet input interface and the lookup of the forwarding table; the processing of downstream packets: the lookup of the forwarding table, etc.

[0209] The physical interface card 1033 is used to implement the docking function at the physical layer. The original traffic enters the interface board 1030 through this card, and the processed packets are sent out from the physical interface card 1033. The physical interface card 1033 includes at least one physical interface, which is also called a physical port. The physical interface card 1033 can also be called a daughter card and can be installed on the interface board 1030. It is responsible for converting optical and electrical signals into packets, performing a legality check on the packets, and then forwarding them to the network processor 1032 for processing. In some embodiments, the central processor 831 of the interface board 1030 can also execute the functions of the network processor 1032, such as implementing software forwarding based on a general-purpose CPU. Thus, the network processor 1032 is not required in the physical interface card 1033.

[0210] Optionally, the network device 1000 includes multiple interface boards. For example, the network device 1000 further includes an interface board 1040, which includes: a central processor 1041, a network processor 1042, a forwarding table entry memory 1044, and a physical interface card 1043.

[0211] Optionally, the network device 1000 further includes a switching fabric board 1020. The switching fabric board 1020 can also be called a switch fabric unit (SFU). When the network device has multiple interface boards 1030, the switching fabric board 1020 is used to complete the data exchange between the interface boards. For example, the interface board 1030 and the interface board 1040 can communicate through the switching fabric board 820.

[0212] The main control board 1010 is coupled to the interface board 1030. For example, the main control board 1010, the interface board 1030, the interface board 1040, and the switching fabric board 1020 are interconnected through the system bus and the system backplane. In a possible implementation, an inter-process communication (IPC) channel is established between the main control board 1010 and the interface board 1030, and the main control board 1010 and the interface board 1030 communicate through the IPC channel.

[0213] Logically, network device 1000 includes a control plane and a forwarding plane. The control plane includes a main control board 1010 and a central processing unit 1031. The forwarding plane includes various components that perform forwarding, such as a forwarding table entry memory 1034, a physical interface card 1033, and a network processor 1032. The control plane executes functions such as acting as a router, generating a forwarding table, processing signaling and protocol packets, and configuring and maintaining the status of the device. The control plane sends the generated forwarding table to the forwarding plane. In the forwarding plane, the network processor 1032 looks up and forwards the packets received by the physical interface card 1033 based on the forwarding table sent by the control plane. The forwarding table sent by the control plane can be stored in the forwarding table entry memory 1034. In some embodiments, the control plane and the forwarding plane can be completely separated and not on the same device.

[0214] If network device 1000 is configured as a first network device, the central processing unit 1011 can determine a second forwarding path according to the indication information in the first SID list. The network processor 1032 can trigger the physical interface card 1033 to send a first response packet of the first BFD packet to the second network device through the second forwarding path.

[0215] If network device 1000 is configured as a second network device, the network processor 1032 can trigger the physical interface card 1033 to send a BFD packet to the first network device through the first forwarding path of the first SR policy, and receive a response packet of the BFD packet from the second forwarding path. The central processing unit 1011 can perform a fault detection on the first forwarding path according to the response packet.

[0216] It should be understood that the receiving unit 701, the sending unit 703, etc. in the fault detection device 700 can be equivalent to the physical interface card 1033 or the physical interface card 1043 in the network device 1000; the determining unit 702, etc. in the fault detection device 700 can be equivalent to the central processing unit 1011 or the central processing unit 1031 in the network device 1000. The sending unit 801, the receiving unit 802, etc. in the fault detection device 800 can be equivalent to the physical interface card 1033 or the physical interface card 1043 in the network device 1000; the detecting unit 803, etc. in the fault detection device 800 can be equivalent to the central processing unit 1011 or the central processing unit 1031 in the network device 1000.

[0217] It should be understood that the operations on interface board 1040 in the embodiments of this application are the same as those on interface board 1030. For the sake of brevity, they will not be elaborated here. It should be understood that the network device 1000 in this embodiment may correspond to any node in the above method embodiments. The main control board 1010, interface board 1030, and / or interface board 1040 in the network device 1000 can implement the functions and / or various steps performed by any node in the above method embodiments. For the sake of brevity, they will not be elaborated here.

[0218] It should be understood that there may be one or more main control boards. When there are multiple main control boards, they may include an active main control board and a standby main control board. There may be one or more interface boards. The stronger the data processing capacity of the network device, the more interface boards are provided. There may also be one or more physical interface cards on the interface board. There may be no switching fabric board, or there may be one or more switching fabric boards. When there are multiple switching fabric boards, they can jointly implement load sharing and redundant backup. In a centralized forwarding architecture, the network device may not require a switching fabric board, and the interface board undertakes the processing function of the service data of the entire system. In a distributed forwarding architecture, the network device may have at least one switching fabric board, and data exchange between multiple interface boards is achieved through the switching fabric board, providing a large-capacity data exchange and processing capacity. Therefore, the data access and processing capabilities of network devices with a distributed architecture are greater than those of devices with a centralized architecture. Optionally, the form of the network device may also be a single board card, that is, without a switching fabric board, and the functions of the interface board and the main control board are integrated on this single board card. At this time, the central processing unit on the interface board and the central processing unit on the main control board can be combined into one central processing unit on this single board card to execute the functions after their superposition. The data exchange and processing capabilities of this form of device are relatively low (for example, network devices such as low-end switches or routers). Which architecture is specifically adopted depends on the specific networking deployment scenario.

[0219] In some possible embodiments, the above nodes may be implemented as virtualized devices. For example, the virtualized device may be a virtual machine (VM) running a program for sending packets, and the virtual machine is deployed on a hardware device (such as a physical server). A virtual machine refers to a complete computer system with complete hardware system functions simulated by software and running in a completely isolated environment. The virtual machine can be configured as each node. For example, each node can be implemented based on a general physical server combined with network function virtualization (NFV) technology. Each node is a virtual host, virtual router, or virtual switch. Those skilled in the art can virtualize each node with the above functions on a general physical server by reading this application in combination with NFV technology, which will not be elaborated here.

[0220] It should be understood that the network devices in the above various product forms respectively have any functions of the nodes in the above method embodiments, which will not be elaborated here.

[0221] Embodiments of the present application further provide a network system 1100, as Figure 11 shown. The network system 1100 may include a first network device 1101 and a second network device 1102. Among them, the first network device 1101 may be Figure 1 the PE device 12 shown in Figure 7 the fault detection device 700 shown in Figure 9 the network device 900 configured as the first network device shown in Figure 10 or the network device 1000 configured as the first network device shown in Figure 1 the PE device 11 shown in Figure 8 the fault detection device 800 shown in Figure 9 the network device 900 configured as the second network device shown in Figure 10 or the network device 1000 configured as the second network device shown in

[0222] Embodiments of the present application further provide a chip, including a processor and an interface circuit. The interface circuit is used to receive instructions and transmit them to the processor; the processor, for example, may be Figure 7 a specific implementation form of the fault detection device 700 shown in Figure 8 and can be used to execute the above method; or for example, it may be

[0223] a specific implementation form of the fault detection device 800 shown in

[0224] and can be used to execute the above method. Among them, the processor is coupled to the memory, and the memory is used to store programs or instructions. When the programs or instructions are executed by the processor, the chip system implements the method in any of the above method embodiments.

[0225] Exemplarily, the chip system may be a field programmable gate array (FPGA), may be an application specific integrated circuit (ASIC), may also be a system on chip (SoC), may also be a central processing unit (CPU), may also be a network processor (NP), may also be a digital signal processing circuit (DSP), may also be a microcontroller unit (MCU), may also be a programmable logic device (PLD) or other integrated chips.

[0226] The embodiment of the present application also provides a computer-readable storage medium, including instructions or a computer program, which, when running on a computer, enables the computer to execute the fault detection method provided in the above embodiments.

[0227] The embodiment of the present application also provides a computer program product including instructions or a computer program, which, when running on a computer, enables the computer to execute the fault detection method provided in the above embodiments.

[0228] The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of the present application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0229] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be described in detail here.

[0230] In several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical service division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections between each other can be through some interfaces, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0231] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0232] In addition, in each embodiment of the present application, each service unit can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software service units.

[0233] If the integrated unit is implemented in the form of a software service unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in each embodiment of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0234] Those skilled in the art should be able to realize that in one or more of the above examples, the operations described in the present invention can be implemented by hardware, software, firmware, or any combination thereof. When implemented using software, these operations can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. The computer-readable medium includes computer storage media and communication media, where the communication media includes any medium that facilitates the transfer of a computer program from one place to another. The storage media can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0235] The above specific implementation manners have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above is only the specific implementation manners of the present invention.

[0236] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application.

Claims

1. A fault detection method, characterized in that, Including: The first network device receives a first Bidirectional Forwarding Detection (BFD) packet sent by the second network device through a first forwarding path of a first Segment Routing with IPv6 (SRv6) policy. The first BFD packet includes a first Binding Segment Identifier (BSID), and the first BSID is used to indicate a first Segment Identifier list (SID list). The first network device determines a second forwarding path according to the first BSID, and the second forwarding path and the first forwarding path are reverse common paths. The first network device sends a first response packet of the first BFD packet to the second network device through the second forwarding path.

2. The method according to claim 1, characterized in that, Before the first network device receives the first BFD packet sent by the second network device through the first forwarding path of the first SR policy, the method further includes: The first network device generates the first BSID; Or, the first network device receives the first BSID sent by the second network device.

3. The method according to claim 1, characterized in that, The method further includes: The first network device receives a message sent by a control and management device, and the message includes the first BSID.

4. The method according to claim 3, characterized in that, The message further includes a second BSID, and the second BSID is used to indicate a second SID list. Among them, the second BSID indicates the first forwarding path, and the first BSID indicates the second forwarding path; or, the second BSID indicates the second forwarding path, and the first BSID indicates the first forwarding path.

5. The method according to claim 3 or 4, characterized in that, The message is a Border Gateway Protocol Segment Routing policy (BGPSR) policy packet, and the BGPSR policy packet carries the first BSID through a subtype length value (sub-TLV) field.

6. The method according to any one of claims 1 - 5, characterized in that, The first SID list is the SID list corresponding to the second forwarding path.

7. The method according to any one of claims 1 - 5, characterized in that, The first SID list is the SID list corresponding to the first forwarding path. When the first network device determines the second forwarding path according to the first BSID, it includes: The first network device determines a second SID list according to the first BSID; The first network device determines the second forwarding path according to the second SID list.

8. A fault detection method, characterized in that, Including: The second network device sends a Bidirectional Forwarding Detection (BFD) packet to the first network device through a first forwarding path of a first Segment Routing with IPv6 (SRv6) policy. The BFD packet includes a first Binding Segment Identifier (BSID), and the first BSID is used to indicate a first Segment Identifier list (SID list). The first BSID is used to indicate that the first network device determines a second forwarding path for sending a response packet of the BFD packet, and the second forwarding path and the first forwarding path are reverse common paths; The second network device receives the response packet of the BFD packet from the second forwarding path.

9. The method according to claim 8, characterized in that, Before the second network device sends a BFD message to the first network device through the first forwarding path of the first SR policy, the method further includes: The second network device receives the first BSID sent by the first network device; Alternatively, the second network device receives the first BSID sent by a control and management device.

10. The method according to claim 8, characterized in that, The method further includes: The second network device generates the first BSID.

11. The method according to claim 10, characterized in that, The method further includes: The second network device sends the first BSID to a control and management device.

12. The method according to claim 11, characterized in that, The second network device sending the first BSID to a control and management device includes: The second network device sends a link state BGP-LS message of the Border Gateway Protocol to the control and management device, and the first BSID is carried in a sub-type length value sub-TLV field of the BGP-LS message.

13. A network device, characterized in that, Includes: A memory, the memory includes computer-readable instructions; A processor communicatively coupled to the memory, the processor is configured to execute the computer-readable instructions such that the network device executes the method according to any one of claims 1-12.

14. A network system, characterized in that, The network system includes: a first network device and a second network device, wherein, the first network device is configured to execute the method according to any one of claims 1-7; The second network device is configured to execute the method according to any one of claims 8-12.

15. A computer-readable storage medium, characterized in that, Includes a program or instructions, which when executed by a processor implement the method according to any one of claims 1-12.

16. A computer program product, characterized in that, Includes a computer program, which when executed by a processor implements the method according to any one of claims 1-12.

17. A fault detection device, characterized in that, Includes: A receiving unit, configured to receive a first Bidirectional Forwarding Detection BFD message sent by a second network device through a first forwarding path of a first Segment Routing based on Internet Protocol version 6 SRv6 policy, the first BFD message includes a first Binding Segment Identifier BSID, and the first BSID is used to indicate a first Segment Identifier list SID list; A determining unit, configured to determine a second forwarding path according to the first BSID, and the second forwarding path and the first forwarding path are reverse common paths; A sending unit, configured to send a first response message of the first BFD message to the second network device through the second forwarding path.

18. The device according to claim 17, characterized in that, The apparatus further includes a generating unit, before the receiving unit receives the first BFD message sent by the second network device through the first forwarding path of the first SR policy, The generating unit is configured to generate the first BSID; Alternatively, the receiving unit is further configured to receive the first BSID sent by the second network device.

19. The device according to claim 17, characterized in that, The receiving unit is further configured to receive a message sent by a control and management device, and the message includes the first BSID.

20. The device according to claim 19, characterized in that, The message further includes a second BSID, where the second BSID is used to indicate a second SID list. Among them, the second BSID indicates the first forwarding path, and the first BSID indicates the second forwarding path; or, the second BSID indicates the second forwarding path, and the first BSID indicates the first forwarding path.

21. The device according to claim 19 or 20, characterized in that, The message is a Border Gateway Protocol Segment Routing Policy (BGPSR) policy message, and the BGPSR policy message carries the first BSID through a sub-Type Length Value (sub-TLV) field.

22. The device according to any one of claims 17-21, characterized in that, The first SID list is the SID list corresponding to the second forwarding path.

23. The device according to any one of claims 17-21, characterized in that, The first SID list is the SID list corresponding to the first forwarding path, where The determining unit is further configured to determine a second SID list according to the first BSID; The determining unit is further configured to determine the second forwarding path according to the second SID list.

24. A fault detection device, characterized in that, including: a sending unit, configured to send a Bidirectional Forwarding Detection (BFD) message to a first network device through a first forwarding path of a first Segment Routing over IPv6 (SRv6) policy. The BFD message includes a first Binding Segment Identifier (BSID), and the first BSID is used to indicate a first Segment Identifier List (SID list). The first BSID is used to instruct the first network device to determine a second forwarding path for sending a response message of the BFD message, and the second forwarding path is reverse co-routed with the first forwarding path; a receiving unit, configured to receive a response message of the BFD message from the second forwarding path.

25. The device according to claim 24, characterized in that, Before the sending unit sends the BFD message to the first network device through the first forwarding path of the first SR policy, the receiving unit is further configured to receive the first BSID sent by the first network device; or, the receiving unit is further configured to receive the first BSID sent by a control and management device.

26. The device according to claim 24, characterized in that,The device further includes a generating unit, where the generating unit is configured to generate the first BSID.

27. The device according to claim 26, wherein, The sending unit is further configured to send the first BSID to a control and management device.

28. The device according to claim 27, wherein, The sending unit is further configured to send a Border Gateway Protocol Link State (BGP-LS) message to the control and management device, and the BGP-LS message carries the first BSID through a sub-TLV field.

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