WO2014008651A1

WO2014008651A1 - Method and routing device for bfd session establishment

Info

Publication number: WO2014008651A1
Application number: PCT/CN2012/078561
Authority: WO
Inventors: 杨杰; 苏现群; 黄永年; 王歆平
Original assignee: 华为技术有限公司
Priority date: 2012-07-12
Filing date: 2012-07-12
Publication date: 2014-01-16
Also published as: CN102918807B; CN102918807A

Abstract

The embodiments of the application provide a method and routing device for BFD session establishment. On one hand, in the embodiments of the application, a first routing device sends a link identifier for identifying the bidirectional link to be detected and a first descriptor assigned by the first routing device for the bidirectional link to be detected to a second routing device, thereby enabling the second routing device to determine the bidirectional link to be detected according to the link identifier, and to create a first relationship of the bidirectional link to be detected, the first descriptor and a second descriptor, wherein the second descriptor is the descriptor assigned by the second routing device for the bidirectional link to be detected; the first routing device further receives a first BFD message sent by the second routing device through the bidirectional link to be detected according the first relationship, wherein the first BFD message comprises the first descriptor and the second descriptor, thereby enabling the first routing device to create a second relationship of the bidirectional link to be detected, the first descriptor and the second descriptor.

Description

BFD session establishment method and routing device

Technical field

The present invention relates to a detection technology, and in particular, to a Bidirectional Forwarding Detection (BFD) session establishment method and a routing device. Background technique

In order to detect network faults, you need to perform Bidirectional Forwarding Detection (BFD). When a fault occurs in the bidirectional link, the service path can be triggered at the same time to protect the service. In dynamic BFD to implement bidirectional link fault detection, one routing device can send BFD packets to another routing device through the bidirectional link to be detected (ie, the bidirectional link), and another routing device performs backhaul processing on the corresponding IP path. The BFD packet is encapsulated in the IP packet and returned to the routing device through the IP path.

However, since the backhaul is processed in the IP path, if the IP path fails, the detection result of the BFD is still a failure of the bidirectional link to be detected, resulting in a decrease in the reliability of the fault detection. Summary of the invention

Aspects of the present application provide a method for establishing a BFD session and a routing device to improve the reliability of fault detection.

An aspect of the present application provides a method for establishing a BFD session, including:

The first routing device sends, to the second routing device, a link identifier for identifying the bidirectional link to be detected and a first descriptor for the first routing device to allocate the bidirectional link to be detected, so that the second Determining, by the routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, the second descriptor Is a descriptor allocated by the second routing device to the to-be-detected bidirectional link;

Receiving, by the first routing device, the first BFD packet sent by the second routing device by using the to-be-detected bidirectional link according to the first association, where the first BFD packet includes the first a descriptor and the second descriptor; The first routing device establishes a second association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and passes the to-be-detected two-way chain according to the second association relationship. The second BFD packet is sent to the second routing device for fault detection, and the second BFD packet includes the first descriptor and the second descriptor.

In a first possible implementation, the to-be-detected bidirectional link includes a first link from the first routing device to the second routing device, and the second routing device to the first route The second link of the device;

When the identifier of the first link is the same as the identifier of the second link, the identifier of the to-be-detected bidirectional link is an identifier of the first link or an identifier of the second link.

With reference to the first possible implementation manner, in a second possible implementation manner, when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is The identifier of the second link.

In combination with the first or second possible implementation manner, in a third possible implementation manner, the first routing device sends, to the second routing device, a link identifier and a location for identifying the bidirectional link to be detected. The first descriptor allocated by the first routing device to the to-be-detected bidirectional link includes:

The first routing device sends the link identifier and the first descriptor to the second routing device by using a control channel between the first routing device and the second routing device.

In combination with the first, second, or third possible implementation manner, in a fourth possible implementation, the first routing device receives the second routing device according to the first association relationship, Before the first BFD packet sent by the bidirectional link to be detected, the method further includes:

The first routing device receives the second descriptor sent by the second routing device by using a control channel between the first routing device and the second routing device.

In combination with the first, second, third, or fourth possible implementation manners, in a fifth possible implementation manner, the first routing device sends, to the second routing device, the identifier that is to be detected. a link identifier of the link and a first descriptor allocated by the first routing device to the to-be-detected bidirectional link, including:

The first routing device sends the link identifier and the first descriptor to the second routing device by using the bidirectional link to be detected.

Another aspect of the present application provides a method for establishing a BFD session, including:

The second routing device receives the link sent by the first routing device to identify the bidirectional link to be detected. Determining, by the first routing device, a first descriptor allocated to the to-be-detected bidirectional link; determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing the to-be-detected a first association relationship between the bidirectional link, the first descriptor, and the second descriptor, where the second descriptor is a descriptor allocated by the second routing device to the bidirectional link to be detected; The second routing device sends a first BFD packet to the first routing device to detect the fault according to the first association relationship, where the first BFD packet includes the first description. And the second descriptor;

Receiving, by the second routing device, the second BFD packet sent by the first routing device by using the to-be-detected bidirectional link according to the second association, where the second BFD packet includes the first descriptor And the second descriptor, the second association relationship is an association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor established by the first routing device.

In a third or a second possible implementation manner, in a third possible implementation manner, the second routing device, according to the first association, passes the to-be-detected bidirectional link to the first Before the routing device sends the first BFD packet for fault detection, it also includes:

The second routing device sends the second descriptor to the first routing device by using a control channel between the first routing device and the second routing device.

Another aspect of the present application provides a routing device, including:

a sending unit, configured to send, to the second routing device, a link identifier used to identify the bidirectional link to be detected and a first descriptor allocated by the routing device to the to-be-detected bidirectional link, so that the second route Determining, according to the link identifier, the bidirectional link to be detected, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, where the second descriptor is Descriptor allocated by the second routing device to the bidirectional link to be detected; a receiving unit, configured to receive, by the second routing device, the first BFD packet that is sent by using the to-be-detected bidirectional link according to the first association, where the first BFD packet includes the first description And the second descriptor;

The association unit is configured to establish a second association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and transmit the second association relationship to the sending unit;

The sending unit is further configured to: send, according to the second association relationship, the second BFD packet to the second routing device by using the to-be-detected bidirectional link to perform fault detection, where the second BFD packet includes The first descriptor and the second descriptor.

In a first possible implementation manner, the to-be-detected bidirectional link includes a first link of the routing device to the second routing device, and a second routing device of the second routing device to the routing device. Link

In combination with the first or second possible implementation manner, in a third possible implementation, the sending unit is specifically used to

And transmitting, by the control channel between the routing device and the second routing device, the link identifier and the first descriptor to the second routing device.

In combination with the first, second or third possible implementation, in a fourth possible implementation, the receiving unit is further used

Receiving, by the second routing device, the second descriptor sent by the control channel between the routing device and the second routing device, and transmitting the second descriptor to the associated unit.

In combination with the first, second, third, or fourth possible implementation manners, in a fifth possible implementation, the sending unit is specifically configured to be used.

The routing device sends the link identifier and the first descriptor to the second routing device by using the bidirectional link to be detected. Another aspect of the present application provides a routing device, including:

a receiving unit, configured to receive a link identifier that is sent by the first routing device to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the bidirectional link to be detected, and the Transmitting the link identifier and the first descriptor to the associated unit;

The association unit is configured to determine the to-be-detected bidirectional link according to the link identifier, and establish a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and Transmitting the first association relationship to a sending unit, where the second descriptor is a descriptor allocated by the routing device to the to-be-detected bidirectional link;

The sending unit is configured to send, by using the to-be-detected bidirectional link, the first BFD packet to the first routing device to perform fault detection according to the first association relationship, where the first BFD packet includes Describe the first descriptor and the second descriptor;

The receiving unit is further configured to receive, by the first routing device, the second BFD packet that is sent by using the to-be-detected bidirectional link according to the second association, where the second BFD packet includes the first a descriptor and the second descriptor, where the second association relationship is an association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor established by the first routing device.

In a first possible implementation, the to-be-detected bidirectional link includes a first link of the first routing device to the routing device, and a second of the routing device to the first routing device. Link

In combination with the first or second possible implementation manner, in a third possible implementation manner, the sending unit is further used to

And transmitting, by the control channel between the first routing device and the routing device, the second descriptor to the first routing device.

Another aspect of the present application provides a routing device, including:

a transmitter, configured to send, to the second routing device, a link identifier used to identify the bidirectional link to be detected and a first descriptor allocated by the routing device to the to-be-detected bidirectional link, so that the second Determining, by the routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, the second descriptor Is a descriptor allocated by the second routing device to the to-be-detected bidirectional link;

a receiver, configured to receive, by the second routing device, the first BFD packet sent by the to-be-detected bidirectional link according to the first association, where the first BFD packet includes the first description And the second descriptor;

The processor is configured to establish a second association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and transmit the second association relationship to the transmitter; The transmitter is further configured to send, by using the to-be-detected bidirectional link, the second BFD packet to the second routing device to perform fault detection according to the second association, where the second BFD packet includes The first descriptor and the second descriptor.

In combination with the first or second possible implementation manner, in a third possible implementation manner, the transmitter is specifically used to

In combination with the first, second or third possible implementation, in a fourth possible implementation, the receiver is further used

Receiving, by the second routing device, the second descriptor sent by the control channel between the routing device and the second routing device, and transmitting the second descriptor to the processor.

In combination with the first, second, third or fourth possible implementation manner, in a fifth possible implementation, the transmitter is specifically used

Transmitting, by the routing device, the two-way link to be detected, to the second routing device A link identifier and the first descriptor.

Another aspect of the present application provides a routing device, including:

a receiver, configured to receive a link identifier sent by the first routing device to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the bidirectional link to be detected, and Transmitting the link identifier and the first descriptor to the processor;

The processor is configured to determine the to-be-detected bidirectional link according to the link identifier, and establish a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and Transmitting the first association relationship to a transmitter, where the second descriptor is a descriptor allocated by the routing device to the to-be-detected bidirectional link;

The transmitter is configured to send, by using the to-be-detected bidirectional link, the first BFD packet to the first routing device to perform fault detection according to the first association relationship, where the first BFD packet includes Describe the first descriptor and the second descriptor;

The receiver is further configured to receive, by the first routing device, the second BFD packet that is sent by using the to-be-detected bidirectional link according to the second association, where the second BFD packet includes the first a descriptor and the second descriptor, where the second association relationship is an association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor established by the first routing device.

In combination with the first or second possible implementation, in a third possible implementation, the transmitter is further used

According to the foregoing technical solution, on the one hand, the first routing device sends a link identifier for identifying the bidirectional link to be detected and the first routing device to the second routing device by using the first routing device. Determining a first descriptor for detecting a bidirectional link allocation, so that the second routing device determines the to-be-detected bidirectional link according to the link identifier, and establishing the to-be-detected bidirectional link, the first a first association relationship between the descriptor and the second descriptor, the second descriptor is a descriptor allocated by the second routing device to the bidirectional link to be detected, and the first routing device further receives the first According to the first association relationship, the second routing device includes the first descriptor and the second descriptor by using the first BFD packet sent by the to-be-detected bidirectional link. Enabling the first routing device to establish the second association relationship of the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and the to-be-detected according to the second association relationship The bidirectional link sends a second BFD packet to the second routing device for fault detection, where the second BFD packet includes the first descriptor and the second descriptor, End routing The device can establish the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, it is not necessary to perform backhaul processing on the IP path, so that the backhaul is avoided in the prior art. If the path of the IP address is faulty, the detection result of the BFD is still the fault of the bidirectional link to be detected, which improves the reliability of fault detection.

According to the foregoing technical solution, on the other hand, the second routing device receives, by the second routing device, the link identifier that is sent by the first routing device to identify the bidirectional link to be detected, and the first routing device is the to-be-detected. a first descriptor of the bidirectional link allocation, and determining the to-be-detected bidirectional link according to the link identifier, and establishing the first to-be-detected bidirectional link, the first descriptor, and the second descriptor The second descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link, and the second routing device further passes the to-be-detected two-way according to the first association relationship. The link sends the first BFD packet to the first routing device to perform fault detection, where the first BFD packet includes the first descriptor and the second descriptor, so that the second routing device can Receiving, by the first routing device, the second BFD packet sent by the to-be-detected bidirectional link according to the second association, where the second BFD packet includes the first descriptor and the second description The second association relationship is an association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor that is established by the first routing device, because both ends of the bidirectional link to be detected are The routing device can establish the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, it is not necessary to perform backhaul processing on the IP path, so that the backhaul in the prior art can be avoided. IP path is processed if the IP path is out If the fault occurs, the detection result of the BFD is still a problem that the bidirectional link to be detected is faulty, thereby improving the reliability of the fault detection. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description of the drawings used in the embodiments or the prior art description will be briefly described below. The drawings are some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any inventive labor.

FIG. 1 is a schematic flowchart of a method for establishing a BFD session according to an embodiment of the present disclosure; FIG. 2 is a schematic flowchart of a method for establishing a BFD session according to another embodiment of the present disclosure; Schematic diagram of the routing device;

4 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure. The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present application. The embodiments are part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the inventive scope are the scope of the present invention.

In addition, the term "and/or" in this context is merely an association describing the associated object, indicating that there may be three relationships, for example, A and / or B, which may indicate: A exists separately, and A and B exist simultaneously. There are three cases of B alone. In addition, the character T in this paper generally indicates that the contextual object is an "or" relationship.

FIG. 1 is a schematic flowchart of a method for establishing a BFD session according to an embodiment of the present disclosure, as shown in FIG. 1 .

The first routing device sends, to the second routing device, a link identifier for identifying the bidirectional link to be detected and a first descriptor that is allocated by the first routing device to the bidirectional link to be detected, so that Determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, The second descriptor is a descriptor allocated by the second routing device for the to-be-detected bidirectional link.

The first routing device receives the first BFD packet that is sent by the second routing device by using the to-be-detected bidirectional link according to the first association, where the first BFD packet includes the a first descriptor and the second descriptor.

103. The first routing device establishes a second association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and the to-be-detected according to the second association relationship. The bidirectional link sends a second BFD packet to the second routing device for fault detection, where the second BFD packet includes the first descriptor and the second descriptor.

At this point, the routing device (ie, the first routing device and the second routing device) at both ends of the bidirectional link to be detected can establish the association between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, the first routing device and the second routing device can use the established association relationship to transmit the BFD packets in the two directions, that is, the first BFD packet and the second BFD packet, by using the to-be-detected bidirectional link. ) for fault detection without the need for backhaul on the IP path.

The bidirectional link to be detected may include, but is not limited to, a Label Switched Path in a Traffic Engineering (TE) tunnel established by a Resource Resert Protocol (RSVP). LSP), LSP or Pseudo Wire (PW) based on Label Distribution Protocol (LDP).

Optionally, in a possible implementation manner of this embodiment, the to-be-detected bidirectional link may include a first link from the first routing device to the second routing device, and the second route The second link of the device to the first routing device.

When the identifier of the first link is the same as the identifier of the second link, the identifier of the to-be-detected bidirectional link may be the identifier of the first link or the identifier of the second link. .

When the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected may be an identifier of the second link.

With the development of the Internet, distributed systems cannot better meet the needs of network scalability and management. Therefore, centralized systems with separate control and forwarding emerge, such as the OpenFlow system. a first routing device (eg, Master, etc.) and a second routing device (eg, an AP, etc.) Communication between the control channels is performed to complete the packet forwarding process that is completely controlled by the switch/router, thereby realizing the separation of data forwarding and routing control.

Optionally, in a possible implementation manner of the embodiment, for the centralized system that separates the control and the forwarding, in the 101, the first routing device may specifically pass the first routing device and the second And a control channel between the routing devices, sending the link identifier and the first descriptor to the second routing device.

Optionally, in a possible implementation manner of this embodiment, before the 102, the first routing device may further receive the second routing device by using the first routing device and the second routing device. Between the control channels, the second descriptor is sent.

Optionally, in a possible implementation manner of the embodiment, for the distributed system, in the 101, the first routing device may send the second routing device to the second routing device by using the to-be-detected bidirectional link. The link identifier and the first descriptor.

In this embodiment, the first routing device sends a link identifier for identifying the bidirectional link to be detected to the second routing device, and a first descriptor that is allocated by the first routing device to the bidirectional link to be detected. So that the second routing device determines the to-be-detected bidirectional link according to the link identifier, and establishes a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, The second descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link, and the first routing device further receives the second routing device according to the first association relationship, Determining to detect the first BFD packet sent by the bidirectional link, where the first BFD packet includes the first descriptor and the second descriptor, so that the first routing device can establish the to-be-detected a bidirectional link, a second association relationship between the first descriptor and the second descriptor, and sending, by the to-be-detected bidirectional link, to the second routing device according to the second association relationship The second BFD packet is configured to detect the fault, and the second BFD packet includes the first descriptor and the second descriptor, and the routing device at both ends of the bidirectional link to be detected can establish the two-way to be detected. The association relationship between the link, the first descriptor, and the second descriptor, therefore, there is no need to perform backhaul processing on the IP path, and it is possible to avoid the IP in the prior art caused by the backhaul being processed in the IP path. If the path is faulty, the detection result of BFD is still the fault of the bidirectional link to be detected, which improves the reliability of fault detection.

In addition, since BFD packets in both directions can pass from one routing device to another routing device through the bidirectional link to be detected (ie, the bidirectional link), there is no need to perform backhaul processing on the IP path. Therefore, the fault detection of the bidirectional link to be detected needs to be completed in one session, thereby reducing the number of interactions between the two routing devices, and saving interaction costs.

FIG. 2 is a schematic flowchart of a method for establishing a BFD session according to another embodiment of the present application, as shown in FIG. 2.

The second routing device receives, by the first routing device, a link identifier that is used to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link.

The second routing device determines the to-be-detected bidirectional link according to the link identifier, and establishes a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. The second descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link.

203. The second routing device sends a first BFD packet to the first routing device to detect a fault according to the first association relationship, where the first BFD packet is included in the first BFD packet. The first descriptor and the second descriptor.

The second routing device receives the second BFD packet sent by the first routing device by using the to-be-detected bidirectional link according to the second association, where the second BFD packet includes the first a descriptor and the second descriptor, where the second association relationship is an association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor established by the first routing device.

Optionally, in a possible implementation manner of this embodiment, the to-be-detected bidirectional link may include a first link from the first routing device to the second routing device, and the second route The second link of the device to the first routing device. When the identifier of the first link is the same as the identifier of the second link, the identifier of the to-be-detected bidirectional link may be the identifier of the first link or the identifier of the second link. .

With the development of the Internet, distributed systems cannot better meet the needs of network scalability and management. Therefore, centralized systems with separate control and forwarding emerge, such as the OpenFlow system. The first routing device (for example, the Master, etc.) communicates with the second routing device (for example, an AP, etc.) through the control channel to jointly complete the packet forwarding process that is completely controlled by the switch/router, thereby implementing data forwarding and Separation of routing control.

Optionally, in a possible implementation manner of this embodiment, for a centralized system that separates control and forwarding, in 201, the second routing device may specifically receive the first routing device by using the first And a control channel between the routing device and the second routing device, the link identifier sent by the first descriptor.

Optionally, in a possible implementation manner of this embodiment, before the 203, the second routing device may further be configured by using a control channel between the first routing device and the second routing device. The first routing device sends the second descriptor.

Optionally, in a possible implementation manner of the embodiment, for the distributed system, the second routing device may receive, by the second routing device, the first routing device by using the to-be-detected bidirectional link. The link identifier and the first descriptor.

In this embodiment, the second routing device receives, by the first routing device, a link identifier that is used by the first routing device to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link. Determining, according to the link identifier, the to-be-detected bidirectional link, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, the second descriptor a descriptor that is allocated by the second routing device to the to-be-detected bidirectional link, and the second routing device, according to the first association relationship, to the first routing device by using the to-be-detected bidirectional link. Sending a first BFD packet to perform fault detection, where the first BFD packet includes the first descriptor and the second descriptor, so that the second routing device can receive the first routing device according to the first a second association relationship, where the second BFD packet is sent by the to-be-detected bidirectional link, where the second BFD packet includes the first descriptor and the second descriptor, where the second association relationship is The first The routing device to establish a bidirectional link to be detected, and the first descriptor The association relationship between the second descriptors, because the routing devices at both ends of the bidirectional link to be detected are capable of establishing the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, therefore, If the IP path is faulty, the detection result of the BFD is still a problem that the bidirectional link to be detected is faulty, so that the backhaul is not processed in the IP path. Improve the reliability of fault detection.

In addition, since the BFD packets in both directions can pass from one routing device to another routing device through the bidirectional link to be detected (ie, the bidirectional link), there is no need to perform backhaul processing on the IP path, therefore, only one The fault detection of the bidirectional link to be detected is completed in the session, thereby reducing the number of interactions between the two routing devices and saving interaction costs.

It should be noted that, for the foregoing method embodiments, for the sake of brevity, they are all described as a series of action combinations, but those skilled in the art should understand that the present application is not limited by the described action sequence. Because certain steps may be performed in other sequences or concurrently in accordance with the present application. In addition, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

In the above embodiments, the descriptions of the various embodiments are different, and the parts that are not detailed in a certain embodiment can be referred to the related descriptions of other embodiments.

FIG. 3 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure. As shown in FIG. 3, the routing device in this embodiment may include a sending unit 31, a receiving unit 32, and an associating unit 33. The sending unit 31 is configured to send, to the second routing device, a link identifier that is used to identify the bidirectional link to be detected, and a first descriptor that is allocated by the routing device to the bidirectional link to be detected, so that the Determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, where the second The descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link; the receiving unit 32 is configured to receive, by the second routing device, the doubly chain to be detected according to the first association relationship. The first BFD packet sent by the path, the first BFD packet includes the first descriptor and the second descriptor, and the association unit 33 is configured to establish the bidirectional link to be detected. Decoding a first descriptor and a second association relationship of the second descriptor, and transmitting the second association relationship to the sending unit 31; the sending unit 31 is further configured to use the second association relationship By the stated The bidirectional link to be detected sends a second BFD packet to the second routing device for fault detection, where the second BFD packet includes the first descriptor and the second descriptor. At this point, the routing device (ie, the routing device and the second routing device) at both ends of the bidirectional link to be detected can establish the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, the routing device and the second routing device can use the established association relationship to transmit the BFD packets in the two directions, that is, the first BFD packet and the second BFD packet, by using the to-be-detected bidirectional link. Fault detection, no need to perform backhaul processing on the IP path.

Optionally, in a possible implementation manner of this embodiment, the link identifier and the first description payment are sent to the second routing device for controlling and forwarding a control channel between separate devices.

Optionally, in a possible implementation manner of the embodiment, the receiving unit 32 may further receive that the second routing device sends by using a control channel between the routing device and the second routing device. Said second descriptor, and transmitting said second descriptor to said associating unit 33. Optionally, in a possible implementation manner of the embodiment, for the distributed system, the sending unit 31 may specifically send, by the routing device, the second routing device to the second routing device by using the to-be-detected bidirectional link. The link identifier and the first descriptor.

In this embodiment, the routing device sends, by the sending unit, a link identifier for identifying the bidirectional link to be detected and a first descriptor allocated by the routing device to the bidirectional link to be detected, to the second routing device, so that Determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, The second descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link, and the receiving unit receives the second routing device, according to the first association relationship, by using the to-be-detected two-way chain. The first BFD packet sent by the path, where the first BFD packet includes the first descriptor and the second descriptor, so that the association unit can establish the bidirectional link to be detected, and the first description And a second association relationship of the second descriptor, and sending, by the sending unit, the second routing device to the second routing device by using the to-be-detected bidirectional link according to the second association relationship The second BFD packet is configured to detect the fault, and the second BFD packet includes the first descriptor and the second descriptor, and the routing device at both ends of the bidirectional link to be detected can establish the two-way to be detected. The association relationship between the link, the first descriptor, and the second descriptor, therefore, there is no need to perform backhaul processing on the IP path, and it is possible to avoid the IP in the prior art caused by the backhaul being processed in the IP path. If the path is faulty, the detection result of BFD is still the fault of the bidirectional link to be detected, which improves the reliability of fault detection.

FIG. 4 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure. As shown in FIG. 4, the routing device in this embodiment may include a receiving unit 41, an association unit 42, and a sending unit 43. The receiving unit 41 is configured to receive, by the first routing device, a link identifier that is used to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link, and Transmitting the link identifier and the first descriptor to the association unit 42; the association unit 42 is configured to determine the to-be-detected bidirectional link according to the link identifier, and establish the to-be-detected two-way chain a first association relationship between the first descriptor and the second descriptor, and the first The association is transmitted to the sending unit 43, the second descriptor is a descriptor allocated by the routing device to the to-be-detected bidirectional link, and the sending unit 43 is configured to pass the first association relationship according to the first association relationship. The detecting the bidirectional link sends the first BFD packet to the first routing device to perform fault detection, where the first BFD packet includes the first descriptor and the second descriptor; the receiving unit The second BFD packet is sent by the first routing device according to the second association relationship, and the second BFD packet is sent by the second BFD packet. The second descriptor, the second association relationship is an association relationship between the to-be-detected bidirectional link established by the first routing device, the first descriptor, and the second descriptor.

So far, the routing device (ie, the first routing device and the routing device) at both ends of the bidirectional link to be detected can establish the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, the first routing device and the routing device can use the established association relationship to transmit the BFD packets in the two directions, that is, the first BFD packet and the second BFD packet, by using the to-be-detected bidirectional link. Fault detection, no need to perform backhaul processing on the IP path.

With the development of the Internet, distributed systems cannot better meet the needs of network scalability and management. Therefore, centralized systems with separate control and forwarding emerge, such as the OpenFlow system. The first routing device (for example, the Master, etc.) communicates with the second routing device (for example, an AP, etc.) through the control channel to jointly complete the packet forwarding process that is completely controlled by the switch/router, thereby implementing data forwarding and Separation of routing control. Optionally, in a possible implementation manner of the embodiment, for the centralized system that controls and forwards the separation, the sending unit 43 may further perform control between the first routing device and the routing device. Channel, sending the second descriptor to the first routing device.

In this embodiment, the routing device receives, by the receiving unit, a link identifier that is sent by the first routing device to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link. And determining, by the association unit, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, where The second descriptor is a descriptor allocated by the routing device to the to-be-detected bidirectional link, and the sending unit sends the first routing device to the first routing device by using the to-be-detected bidirectional link according to the first association relationship. Performing a fault detection on a BFD packet, where the first BFD packet includes the first descriptor and the second descriptor, so that the receiving unit can receive the first routing device according to the second association relationship. a second BFD packet sent by the bidirectional link to be detected, where the second BFD packet includes the first descriptor and the second descriptor, and the second association relationship is The relationship between the two-way link to be detected, the first descriptor, and the second descriptor that is established by the first routing device, because the routing devices at both ends of the bidirectional link to be detected can establish the to-be-detected The association relationship between the bidirectional link, the first descriptor, and the second descriptor, therefore, there is no need to perform backhaul processing on the IP path, and it is possible to avoid the prior art if the backhaul is processed in the IP path. If the IP path is faulty, the detection result of BFD is still the fault of the bidirectional link to be detected, which improves the reliability of fault detection.

FIG. 5 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure. As shown in FIG. 5, the routing device in this embodiment may include a transmitter 51, a receiver 52, and a processor 53. The transmitter 51 is configured to send, to the second routing device, a link identifier that is used to identify the bidirectional link to be detected, and a first descriptor that is allocated by the routing device to the bidirectional link to be detected, so that the Determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, where the second a descriptor is a descriptor allocated by the second routing device to the bidirectional link to be detected; a receiver 52 is configured to connect Receiving, by the second routing device, the first BFD packet 53 sent by the to-be-detected bidirectional link according to the first association, the first BFD packet includes the first descriptor and the a second descriptor; the processor 53 is configured to establish a second association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, and transmit the second association relationship The transmitter 51 is further configured to send, by using the to-be-detected bidirectional link, the second BFD packet to the second routing device to perform fault detection according to the second association relationship. The first BFD message includes the first descriptor and the second descriptor.

At this point, the routing device (ie, the routing device and the second routing device) at both ends of the bidirectional link to be detected can establish the association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor. Therefore, the routing device and the second routing device can use the established association relationship to transmit the BFD packets in the two directions, that is, the first BFD packet and the second BFD packet, by using the to-be-detected bidirectional link. Fault detection, no need to perform backhaul processing on the IP path.

Optionally, in a possible implementation manner of this embodiment, the control and forwarding are separated. In a centralized system, the transmitter 51 may specifically send the link identifier and the first descriptor to the second routing device by using a control channel between the routing device and the second routing device.

Optionally, in a possible implementation manner of the embodiment, the receiver 52 may further receive that the second routing device sends by using a control channel between the routing device and the second routing device. Said second descriptor, and transmitting said second descriptor to said processor 53.

Optionally, in a possible implementation manner of the embodiment, for the distributed system, the sending device 51 may specifically send, by the routing device, the second routing device to the second routing device by using the to-be-detected bidirectional link. The link identifier and the first descriptor.

In this embodiment, the routing device sends, by using a transmitter, a link identifier for identifying the bidirectional link to be detected and a first descriptor allocated by the routing device to the bidirectional link to be detected, to the second routing device, so that Determining, by the second routing device, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, The second descriptor is a descriptor allocated by the second routing device to the to-be-detected bidirectional link, and the receiver receives the second routing device by the receiver according to the first association relationship, by using the to-be-detected two-way chain. a first BFD packet sent by the path, where the first BFD packet includes the first descriptor and the second descriptor, so that the processor can establish the bidirectional link to be detected, and the first description And a second association relationship of the second descriptor, and sending, by the sender, the second BF to the second routing device by using the to-be-detected bidirectional link according to the second association relationship The D packet is fault-detected, and the second BFD packet includes the first descriptor and the second descriptor, and the routing device at both ends of the bidirectional link to be detected can establish the bidirectional link to be detected. The association relationship between the first descriptor and the second descriptor, therefore, there is no need to perform backhaul processing on the IP path, and it can be avoided if the IP path appears in the prior art because the backhaul is processed in the IP path. If the fault occurs, the detection result of BFD is still the fault of the bidirectional link to be detected, which improves the reliability of fault detection.

FIG. 6 is a schematic structural diagram of a routing device according to another embodiment of the present disclosure, as shown in FIG. The routing device of this embodiment may include a receiver 61, a processor 62, and a transmitter 63. The receiver 61 is configured to receive, by the first routing device, a link identifier that is used to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link, and Transmitting the link identifier and the first descriptor to the processor 62; the processor 62, configured to determine the to-be-detected bidirectional link according to the link identifier, and establish the to-be-detected two-way chain a first association relationship between the first descriptor and the second descriptor, and transmitting the first association relationship to the transmitter 63, where the second descriptor is that the routing device is the two-way to be detected a descriptor for the link allocation, the transmitter 63, configured to send, by using the to-be-detected bidirectional link, the first BFD packet to the first routing device to perform fault detection according to the first association relationship, where The first BFD packet includes the first descriptor and the second descriptor, and the receiver 61 is further configured to receive, by the first routing device, the doubly chain to be detected according to the second association relationship. Second BFD packet sent by the road The second BFD packet includes the first descriptor and the second descriptor, where the second association relationship is the to-be-detected bidirectional link established by the first routing device, and the A descriptor and an association relationship of the second descriptor.

The bidirectional link to be detected may include but is not limited to a resource reservation protocol.

(Recycled Switching Path (LSP) in the Traffic Engineering (TE) Tunnel, LSP or Pseudo-based Label Distribution Protocol (LDP) established by the Resource ReSerVation Protocol (RSVP) Line (Pseudo Wire, PW).

When the identifier of the first link is different from the identifier of the second link, the two-way to be detected The identifier of the link may be the identifier of the second link.

Optionally, in a possible implementation manner of this embodiment, the transmitter 63 may further perform control between the first routing device and the routing device for a centralized system that separates control and forwarding. Channel, sending the second descriptor to the first routing device.

In this embodiment, the routing device receives, by the receiver, a link identifier that is sent by the first routing device to identify the bidirectional link to be detected, and a first descriptor that is allocated by the first routing device to the to-be-detected bidirectional link. Determining, by the processor, the bidirectional link to be detected according to the link identifier, and establishing a first association relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor, where The second descriptor is a descriptor allocated by the routing device to the to-be-detected bidirectional link, and the sender sends the first routing device to the first routing device by using the to-be-detected bidirectional link according to the first association relationship. Performing a fault detection on a BFD packet, where the first BFD packet includes the first descriptor and the second descriptor, so that the receiver can receive the first routing device according to the second association relationship. a second BFD packet sent by the bidirectional link to be detected, where the second BFD packet includes the first descriptor and the second descriptor, where the second association relationship is The relationship between the to-be-detected bidirectional link, the first descriptor, and the second descriptor established by the routing device, because the routing devices at both ends of the bidirectional link to be detected can establish the bidirectional link to be detected, The association relationship between the first descriptor and the second descriptor, therefore, there is no need to perform backhaul processing on the IP path, and it is possible to avoid the failure of the IP path caused by the backhaul being processed in the IP path in the prior art. The detection result of the BFD is still a problem that the bidirectional link to be detected is faulty, thereby improving the reliability of the fault detection.

It will be apparent to those skilled in the art that the above description is convenient and concise for the description. For the specific working process of the system, the device and the unit, refer to the corresponding process in the foregoing method embodiment, and details are not described herein again.

In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not executed. In addition, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be electrical, mechanical or otherwise.

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, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional units.

Finally, it should be noted that the above embodiments are only used to explain the technical solutions of the present application, and are not limited thereto; although the present application is described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced.

Claims

claims

1. A method for bidirectional forwarding detection of BFD session establishment, characterized in that it includes: the first routing device sends to the second routing device a link identifier used to identify the bidirectional link to be detected and the first routing device is the The first descriptor of the bidirectional link to be detected is allocated, so that the second routing device determines the bidirectional link to be detected based on the link identifier, and establishes the bidirectional link to be detected, the first A first association relationship between a descriptor and a second descriptor, where the second descriptor is a descriptor allocated by the second routing device for the bidirectional link to be detected;

The first routing device receives a first BFD message sent by the second routing device through the bidirectional link to be detected according to the first association relationship, and the first BFD message includes the first descriptor and said second descriptor;

The first routing device establishes a second association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, and according to the second association relationship, through the bidirectional link to be detected The router sends a second BFD message to the second routing device for fault detection, where the second BFD message includes the first descriptor and the second descriptor.

2. The method of claim 1, wherein the bidirectional link to be detected includes a first link from the first routing device to the second routing device, and a link from the second routing device to the second link of the first routing device;

When the identifier of the first link is the same as the identifier of the second link, the identifier of the bidirectional link to be detected is the identifier of the first link or the identifier of the second link.

3. The method according to claim 2, characterized in that, when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the second link. The link's identifier.

4. The method according to any one of claims 1 to 3, characterized in that, the first routing device sends a link identifier used to identify the bidirectional link to be detected and the first routing device to the second routing device. The first descriptor allocated by the routing device for the bidirectional link to be detected includes:

The first routing device sends the link identifier and the first descriptor to the second routing device through a control channel between the first routing device and the second routing device.

5. The method according to any one of claims 1 to 4, characterized in that, the first routing device receives, according to the first association relationship, the second routing device through the bidirectional link to be detected. Before sending the first BFD message, it also includes: The first routing device receives the second descriptor sent by the second routing device through a control channel between the first routing device and the second routing device.

6. The method according to any one of claims 1 to 5, characterized in that, the first routing device sends a link identifier used to identify the bidirectional link to be detected and the first routing device to the second routing device. The first descriptor allocated by the routing device for the bidirectional link to be detected includes:

The first routing device sends the link identifier and the first descriptor to the second routing device through the bidirectional link to be detected.

7. A bidirectional forwarding detection BFD session establishment method, characterized in that it includes: the second routing device receives a link identifier sent by the first routing device to identify the bidirectional link to be detected and the first routing device is the Describe the first descriptor of the bidirectional link allocation to be detected;

The second routing device determines the bidirectional link to be detected based on the link identifier, and establishes a first association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, The second descriptor is a descriptor allocated by the second routing device to the bidirectional link to be detected; the second routing device sends a message to the third bidirectional link through the bidirectional link to be detected based on the first association relationship. A routing device sends a first BFD message for fault detection, where the first BFD message includes the first descriptor and the second descriptor;

The second routing device receives a second BFD message sent by the first routing device through the bidirectional link to be detected according to the second association relationship, and the second BFD message includes the first descriptor. and the second descriptor, and the second association relationship is an association relationship between the bidirectional link to be detected, the first descriptor, and the second descriptor established by the first routing device.

8. The method of claim 7, wherein the bidirectional link to be detected includes a first link from the first routing device to the second routing device, and a link from the second routing device to the second link of the first routing device;

9. The method according to claim 8, characterized in that, when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the second link. The link's identifier.

10. The method according to any one of claims 7 to 9, characterized in that, according to the first association relationship, the second routing device transmits data to the first path through the bidirectional link to be detected. Before the device sends the first BFD message for fault detection, it also includes:

The second routing device sends the second descriptor to the first routing device through a control channel between the first routing device and the second routing device.

1 1. A routing device, characterized by including:

A sending unit configured to send a link identifier used to identify the bidirectional link to be detected and a first descriptor allocated by the routing device for the bidirectional link to be detected to the second routing device, so that the second routing device The device determines the bidirectional link to be detected based on the link identifier, and establishes a first association relationship between the bidirectional link to be detected, the first descriptor, and the second descriptor, where the second descriptor is The descriptor assigned by the second routing device to the bidirectional link to be detected;

A receiving unit configured to receive a first bidirectional forwarding detection BFD message sent by the second routing device through the bidirectional link to be detected according to the first association relationship, where the first BFD message contains the a first descriptor and said second descriptor;

The association unit is configured to establish a second association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, and transmit the second association relationship to the sending unit;

The sending unit is further configured to send a second BFD message to the second routing device through the bidirectional link to be detected for fault detection according to the second association relationship, and the second BFD message contains the first descriptor and the second descriptor.

12. The routing device according to claim 11, wherein the bidirectional link to be detected includes a first link from the routing device to the second routing device, and a link from the second routing device to The second link of the routing device;

13. The routing device according to claim 12, wherein when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the third link. The identification of the second link.

14. The routing device according to any one of claims 11 to 13, characterized in that the sending unit is specifically used to

The link identifier and the first descriptor are sent to the second routing device through a control channel between the routing device and the second routing device.

15. The routing device according to any one of claims 11 to 14, characterized in that the receiving unit is also used to

Receive the second descriptor sent by the second routing device through the control channel between the routing device and the second routing device, and transmit the second descriptor to the association unit.

16. The routing device according to any one of claims 11 to 15, characterized in that the sending unit is specifically used to

The routing device sends the link identifier and the first descriptor to the second routing device through the bidirectional link to be detected.

17. A routing device, characterized by including:

A receiving unit configured to receive a link identifier sent by the first routing device for identifying the bidirectional link to be detected and a first descriptor allocated by the first routing device for the bidirectional link to be detected, and convert the The link identification and the first descriptor are transmitted to the association unit;

The association unit is configured to determine the bidirectional link to be detected based on the link identifier, and establish a first association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, and Transmit the first association relationship to the sending unit, and the second descriptor is a descriptor allocated by the routing device for the bidirectional link to be detected;

The sending unit is configured to send a first bidirectional forwarding detection BFD message to the first routing device through the bidirectional link to be detected for fault detection according to the first association relationship, and the -th BFD message contains the first descriptor and the second descriptor;

The receiving unit is also configured to receive a second BFD message sent by the first routing device through the bidirectional link to be detected according to the second association relationship, where the second BFD message contains the first descriptor and the second descriptor, and the second association relationship is an association relationship between the bidirectional link to be detected, the first descriptor, and the second descriptor established by the first routing device.

18. The routing device according to claim 17, wherein the bidirectional link to be detected includes a first link from the first routing device to the routing device, and a link from the routing device to the third routing device. A second link to the routing device;

19. The routing device according to claim 18, characterized in that when the first link When the identifier of is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the identifier of the second link.

20. The routing device according to any one of claims 17 to 19, characterized in that the sending unit is also used to

The second descriptor is sent to the first routing device through a control channel between the first routing device and the routing device.

21. A routing device, characterized by including:

A sender configured to send a link identifier used to identify the bidirectional link to be detected and a first descriptor allocated by the routing device for the bidirectional link to be detected to the second routing device, so that the second routing device The device determines the bidirectional link to be detected based on the link identifier, and establishes a first association relationship between the bidirectional link to be detected, the first descriptor, and the second descriptor, where the second descriptor is The descriptor assigned by the second routing device to the bidirectional link to be detected;

A receiver configured to receive a first bidirectional forwarding detection BFD message sent by the second routing device through the bidirectional link to be detected according to the first association relationship, where the first BFD message contains the a first descriptor and said second descriptor;

The processor is configured to establish a second association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, and transmit the second association relationship to the sender; The sender is further configured to send a second BFD message to the second routing device through the bidirectional link to be detected for fault detection according to the second association relationship, and the second BFD message contains the first descriptor and the second descriptor.

22. The routing device according to claim 21, wherein the bidirectional link to be detected includes a first link from the routing device to the second routing device, and a link from the second routing device to the second routing device. The second link of the routing device;

23. The routing device according to claim 22, wherein when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the third link. The identification of the second link.

24. The routing device according to any one of claims 21 to 23, characterized in that the transmitter is specifically used for The link identifier and the first descriptor are sent to the second routing device through a control channel between the routing device and the second routing device.

25. The routing device according to any one of claims 21 to 24, characterized in that the receiver is also used for

Receive the second descriptor sent by the second routing device through the control channel between the routing device and the second routing device, and transmit the second descriptor to the processor.

26. The routing device according to any one of claims 21 to 25, characterized in that the transmitter is specifically used for

27. A routing device, characterized by including:

A receiver configured to receive a link identifier sent by the first routing device for identifying the bidirectional link to be detected and a first descriptor allocated by the first routing device for the bidirectional link to be detected, and convert the The link identification and the first descriptor are transmitted to the processor;

The processor is configured to determine the bidirectional link to be detected based on the link identifier, and establish a first association relationship between the bidirectional link to be detected, the first descriptor and the second descriptor, and Transmit the first association relationship to the sender, and the second descriptor is a descriptor allocated by the routing device for the bidirectional link to be detected;

The sender is configured to send a first bidirectional forwarding detection BFD message to the first routing device through the bidirectional link to be detected for fault detection according to the first association relationship, the first BFD message contains the first descriptor and the second descriptor;

The receiver is further configured to receive a second BFD message sent by the first routing device through the bidirectional link to be detected according to the second association relationship, where the second BFD message contains the first descriptor and the second descriptor, and the second association relationship is an association relationship between the bidirectional link to be detected, the first descriptor, and the second descriptor established by the first routing device.

28. The routing device according to claim 27, wherein the bidirectional link to be detected includes a first link from the first routing device to the routing device, and a link from the routing device to the third routing device. A second link to the routing device;

29. The routing device according to claim 28, wherein when the identifier of the first link is different from the identifier of the second link, the identifier of the bidirectional link to be detected is the third link. The identification of the second link.

30. The routing device according to any one of claims 27 to 29, characterized in that the transmitter is also used for