WO2008064612A1

WO2008064612A1 - A method and device and system for performing fast rerouting in a mpls network

Info

Publication number: WO2008064612A1
Application number: PCT/CN2007/071153
Authority: WO
Inventors: Haiyan Zhang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-11-30
Filing date: 2007-11-29
Publication date: 2008-06-05
Also published as: CN101192990A

Abstract

A method, device and system for performing fast rerouting in a MPLS network, the said method comprises that a source node of a protection LSP(label switching path) establishes a protection LSP to a work LSP destination node along a protection ring direction in a ring topology so as to fast reroute the protection ring with the protection LSP.

Description

Method, device and system for implementing fast rerouting in MPLS network

[1] Technical field

[2] The present invention relates to the field of network communication technologies, and in particular, to a method and system for implementing fast rerouting for MPLS (Multi Protocol Label Switching).

[3] Background of the invention

[4] MPLS is a system for fast packet switching and routing that provides routing, forwarding, and switching capabilities for network data traffic. To improve the reliability of information transfer in MPLS networks, the IETF (Internet Engineering Task Force) organization proposed a fast rerouting mechanism. The fast rerouting technology provides fast protection switching capability for LSPs (Label Switching Paths) by means of MPLS traffic engineering capabilities.

[5] The specific implementation process of MPLS fast reroute includes: Pre-establishing a local backup path as a protection LSP

The protection LSP requirement is not affected by the link or node failure, so that when the failure occurs, the device detecting the link or the node failure can quickly switch the service to the protection L SP as the backup path. Up, thereby reducing the amount of data loss transmitted via the MPLS network.

[6] MPLS fast reroute has the characteristics of rapid response and handover. Therefore, it can ensure smooth transition of service data without causing service interruption. Similarly, the source node of LSP will try to find a new path. The LSP is re-established and the data is switched to the new path. Before the new LSP is established successfully, the service data is always forwarded through the protection path.

[7] The IETF's MPLS Working Group extended RSVP-TE (Resource Reservation Extension Protocol) signaling in its draft standard RFC4090, adding a 1: 1 protection scheme for linear point-to-point LSP fast reroute. .

[8] The protection scheme of the 1:1 protection mode is: Create a protection path for each potential local repair point in the protected LSP.

[9] In the 1:1 protection mode, a working LSP is established through traffic engineering-based RSVP-TE signaling, and the signaling carries the requirements for protection and the attributes of the required protection LSP. Each node on the working LSP except the sink node is a potential PLR (local repair node). According to the signaling and local policy of the working LSP, the PLR calculates and establishes a protection LSP from the PLR to the working LSP sink node to protect it. Downstream link And nodes.

[10] As shown in Figure 1, the working LSP path is: [R1, R2, R3, R4, R5, R6], and the corresponding protection LSP includes the following two:

[11] Alternate LSP1 with the path [R2, R7, R8, R9, R4, R5, R6], which can provide protection after the link between R2 node and R3 node or R3 node fails.

[12] Alternate LSP2, whose path is [R3, R8, R9, R5, R6], which can be linked between R3 nodes and R4 nodes or

The R4 node is faulty and provides protection.

[13] The existing re-routing protection technology can be applied to the ring topology network to implement point-to-point LSP fast re-routing. However, it is not difficult to see that in the prior art, the working LSP is protected and needs to be in the working LSP. Each node except the sink node establishes a corresponding protection LSP for its downstream link or node. Therefore, if a reliable protection is provided, multiple protection LSPs need to be established, which inevitably leads to complex implementation in the process of providing protection for the working LSP. The problem of occupying more network resources.

[14] Summary of the invention

[15] The present invention provides a method, a device, and a system for implementing fast re-routing in an MPLS network, thereby facilitating fast re-routing in an MPLS network and providing protection for an LSP.

[16] The present invention provides a method for implementing fast rerouting in an MPLS network, the method is applied to an MPLS network, and the method includes:

[17] In the ring topology, the node on the working LSP is used as the source node of the protection LSP. From the source node, the protection LSP between the working LSP and the working LSP is established in the opposite direction of the working LSP. The SP implements fast reroute protection.

[18] The present invention also provides a node device for implementing fast rerouting, which is used in an MPLS network, and includes:

[19] The protection LSP establishing unit is configured to perform protection of the LSP establishment message to control the establishment of the protection LSP between the local and working LSP sink nodes in the reverse direction of the working LSP;

[20] The protection processing unit is configured to implement fast reroute protection for the working LSP by using the protection LSP established by the protection LSP establishment unit after the working LSP fails.

[21] The present invention also provides a system for implementing fast rerouting in an MPLS network, the system is disposed in an MPLS network, and the system includes: [22] The protection LSP establishment unit is set in the nodes of each ring topology, and is used as the source node of the protection LSP, and the protection between the working LSP and the working LSP is established from the source node. LSP;

[23] The protection processing unit is configured in multiple nodes of the ring topology to protect the working LSP and implement fast reroute protection after the working LSP fails.

[24] It can be seen that the foregoing technical solution provided by the present invention can establish a protection LSP in a ring topology to implement fast re-routing protection for multiple nodes and links without establishing multiple protection LSP pairs. The node and the link are protected. Therefore, the implementation of the present invention can obviously reduce the storage capacity of the protection link information during the protection process for the working LSP in the MPLS network, thereby effectively reducing the bandwidth resources in the network. Occupy. Moreover, since it is not necessary to establish multiple protection LSPs, the processing overhead of the control plane in the MPLS network can be effectively reduced, thereby effectively improving the processing efficiency of the protection switching, and thereby improving the communication performance of the entire network.

[25] BRIEF DESCRIPTION OF THE DRAWINGS

[26] FIG. 1 is a schematic diagram of protection in the prior art 1;

2 is a flowchart of establishing a protection LSP according to Embodiment 1 of the present invention;

[28] FIG. 3 is a schematic diagram of establishing a protection LSP according to Embodiment 2 of the present invention;

[29] FIG. 4 is a schematic diagram of a protection LSP being switched after a fault occurs in Embodiment 2 of the present invention;

FIG. 5 is a schematic structural diagram of an embodiment of a node device according to the present invention.

[31] Mode for carrying out the invention

[32] The present invention is applied to the ring topology, and the protection LSP can be established between the protection ring direction and the working LSP sink node by the source node of the protection LSP in the working ring to implement fast rerouting protection.

[33] Specifically, in the implementation of the rerouting protection in the ring topology of the present invention, the following processes are specifically included:

[34] First, in the process of establishing a working LSP, the protection attribute is advertised to each node in the working LSP, and the source node protecting the LSP is determined.

[35] After determining the source node of the protection LSP, a protection LSP from the source node of the protection LSP to the protection LSP sink node is established in the opposite direction of the working LSP on the protection ring.

[36] In the process of establishing the protection LSP, the PLR needs to bind the forwarding relationship between the working LSP and the protection LSP. For subsequent protection switching applications.

[37] After the protection LSP is successfully established, when the link or node of the working LSP fails, the node that detects the fault or receives the fault information performs protection switching, and forwards the service to the sink node of the working LSP through the protection LSP. The protection of services is implemented within the ring topology.

The invention will now be described in detail in conjunction with the drawings of specific embodiments of the invention.

As shown in FIG. 2, the process for establishing a protection LSP according to the first embodiment of the present invention may specifically include the following steps.

[40] Step 1: The source node initiates a working LSP setup message carrying the protection attribute to the sink node, and the sink node returns a working LSP setup response message to establish a working LSP.

[41] In the ring topology of the first embodiment, the source node initiates a working LSP setup message to the sink node, and requests to establish a working LSP with the sink node, and carries the protection attribute in the working LSP setup message, where the message works. Each node of the LSP is forwarded to the sink node.

[42] In the first embodiment, a path message may be used as a working LSP to establish a message; [43] the protection attributes may include: a local protection requirement, a node protection requirement, a bandwidth protection requirement, a protection LSP attribute, and Ring protection attributes, etc.

[44] The sink node receives the working LSP setup message, returns a working LSP response message to the source node, and establishes a working LSP between the source node and the sink node;

[45] The sink node replies to the working LSP establishment response message described in this embodiment may be a reservation message (Resv

Message).

[46] After the establishment of the LSP is completed, the corresponding protection LSP can be established according to the established working LSP. The specific processing procedure is as follows:

[47] Step 2: The node that receives the LSP setup message determines whether it is a non-sink node on the working LSP. If the node is a working LSP node and is a corresponding non-sink node, step 3 is performed; For the sink node on the working LSP, or the node is a node on the non-working LSP, go to step 6;

[48] After receiving the LSP establishment message, the node in the ring topology may be the message for establishing the working LSP, or the message for establishing the protection LSP. Therefore, whether the node needs to be based on whether the node is The non-sink node on the working LSP determines a processing manner for the corresponding message, where the processing for the message for establishing the protection LSP is included; Path that receives the working LSP on the ring topology.

The node of the message message is a node on the working LSP, and a node on other non-working LSPs on the ring;

[50] After determining the node working LSP, further according to the path message of the working LSP (Path

Message) or reservation message (Resv

The information carried in the Message determines whether the node is a sink node of the working LSP, so as to implement corresponding processing in this step;

[51] Step 3: Detecting whether the non-sink nodes of the LSP protect the source node of the LSP;

[52] In the process of applying the present invention, any node other than the sink node on the working LSP may be selected as the source node of the protection LSP;

[53] The manner in which each non-sink node on the specific working LSP determines to protect the LSP source node may include: establishing a working LSP, and carrying the source of the protection LS P in the setup message sent by the source node or the response message sent by the sink node Node information; or the network management party needs to specify a node as the source node of the protection LSP according to the protection of the working LSP, and directly configure the node as the source node of the protection LSP, for example, set the penultimate hop in the working LSP to Protect the source node of the LSP;

[54] Each non-sink node of the working LSP obtains the source node information of the protection LSP by the above method, and can determine whether the node is the source node of the protection LSP, and:

[55] When a node other than the sink node on the working LSP is the source node of the protection LSP, step 4 is performed;

[56] When a node other than the sink node on the working LSP is a non-source node protecting the LSP, step 5 is performed;

[57] Step 4. Protect the source node of the LSP to establish a protection LSP.

[58] When a node other than the sink node on the working LSP is the source node of the protection LSP, the node sends a protection LSP establishment message to the sink node in the opposite direction of the working ring on the guard ring;

[59] Peer, protect the source node of the LSP as step 7 of the PLR.

[60] Step 5. The node outside the sink node on the working LSP receives the Path Message or Resv that protects the LSP.

Message: If the node does not protect the source node of the LSP, it forwards the received protection LSP message directly downstream or upstream.

[61] The peer determines whether the node is a PLR according to the local policy. If the node needs to be a PLR, go to step 7. Otherwise, you do not need to perform step 7, and directly forward the corresponding message.

[62] Step 6, as a normal LSP establishment process, and perform step 8; [63] The node on the non-working LSP on the ring directly forwards the received protection LSP message to the downstream or upstream. After receiving the protection LSP establishment message, the sink node on the working LSP sends a response message to the upstream protection LSP.

[64] Step 7. From the source node protecting the LSP to the protection LSP sink node, and as a PL in the ring topology

The node of the R is bound to the forwarding relationship between the working LSP and the protection LSP, and step 8 is performed;

[65] During the establishment of the protection LSP, the PLR will refer to the Path Message and Resv

The assigned label and the corresponding outbound interface information carried in the message are mapped to the corresponding forwarding table of the working LSP, and the binding between the working LSP and the protection LSP is implemented in the PLR.

[66] The protection LSP establishment message and the protection LSP establishment response message in the embodiment carry an explicit route, and the explicit route is limited to the protection ring.

[67] Step 8. At this point, the protection LSP of the working LSP is successfully established in the ring topology.

[68] Step 9. The PLR reports the updated protection status to the source node of the working LSP.

[69] In each of the above steps, each node in the ring topology may select a platform-based tag space or an interface-based tag space on the type of tag space used.

[70] If a platform-based tag space is used and an LSP is to be identified by a unique tag, the unique tag requirements for the working and protection LSPs cannot be the same;

[71] If the platform-based label space or interface-based label space is used in addition to the above, there is no such restriction. The label of each LSP is unconstrained, and the label between the working and protection LSPs has no constraint. .

[72] In order to describe the content of the present invention in detail, a node working LSP is selected as the source of the protection LSP, and the establishment of the protection LSP and the protection switching process are specifically introduced.

As shown in FIG. 3, it is a schematic diagram of establishing a protection LSP according to Embodiment 2 of the present invention. In this figure, the penultimate hop of the working LSP is selected as the source node of the protection LSP.

As shown in Figure 3, node 3 is the source node of the working LSP, node 8 is the sink node of the working LSP, and node 7 is the source node of the protection LSP, which is the penultimate hop node of the working LSP.

[75] Node 7 passes the path of the working LSP

The protection attribute carried in the message determines that the establishment of the protection LSP by the penultimate hop is required in the working LSP, and the node 7 passes the Resv. The explicit route [3, 4, 5, 6, 7, 8] carried in the message determines that the local node is the penultimate hop of the working LSP. Therefore, node 7 initiates the path along the guard ring (reverse 吋).

Message, that is, the Path Message is initiated in the reverse direction of the working ring (shunning pin) to establish a protection LSP.

[76] Peer node 7 as PLR, will protect the LSP message Path Message or Resv

The label and corresponding outbound interface information in the message are mapped to the corresponding forwarding table of the working LSP, and the forwarding relationship between the working LSP and the protection LSP is bound.

[77] The Path to Protect the LSP

The explicit route carried in the message is limited to the protection ring, that is, [7,6,5,4,3,2,1,8], and the source node is working.

The penultimate hop node of the LSP 7, the sink node is the sink node of the working LSP 8.

[78] Node 6 passes the Resv of the working LSP

The explicit route [3, 4, 5, 6, 7, 8] carried in the message determines the penultimate hop of the non-working LSP of the node, and the node 6 forwards the path of the received protection LSP to the downstream node 5.

Message, when receiving the reverse Resv based on the protection LSP

Message吋 forwards the corresponding message upstream.

[79] Node 6 determines the local node as a PLR according to the local policy, and will protect the LSP message (Path

Message or Resv

[80] The other nodes ₅ , ₄ , and 3 in the ring can be used as the PLR, which is the same as the processing of the node 6, and therefore will not be explained one by one.

[81] The nodes on the other non-working LSPs on the ring, including the node 2, 1, and the sink node 8 of the working LSP, are consistent with the establishment of the normal LSP.

[82] After receiving the Path Message of the protection LSP, the sink node 8 will return to the node [8, 1, 2, 3, 4, 5, 6, 7] Resv

Message to the penultimate hop node 7, the protection LSP is successfully established.

[83] PLR through working LSP Resv Message in RRO

The status indicator carried by the Sub-Object reports the status of the protection LSP to the source node of the working LSP, including whether the local protection is available, whether local protection is enabled, whether bandwidth protection is provided, whether ring protection is provided, etc. [84] FIG. 4 is a schematic diagram of the operation of performing protection switching after a link between nodes 5 and 6 fails in the second embodiment of the present invention.

[85] In the embodiment of the present invention, after the working LSP is protected, there are multiple protection switching methods.

[86] The upstream node 5 of the fault detects the fault, initiates a protection switchover, and sets the corresponding switchover state in the forwarding table corresponding to the faulty LSP. The corresponding service received by the subsequent node 5 exchanges labels according to the index of the forwarding table, and presses the corresponding outgoing interface. Forwarding, the route of the service after protection switching is [3, 4, 5, 4, 3, 2, 1, 8];

[87] Or, the fault upstream node 5 detects the fault, sends the alarm information to the source node 3 through the guard ring, and the source node 3 initiates the protection switch after receiving the alarm information, and the corresponding switch state in the forwarding table corresponding to the fault LSP is set, followed. The corresponding service sent by the source node 3 exchanges labels according to the index of the forwarding table, and is forwarded according to the corresponding outbound interface. The route of the service after protection switching is [3, 2, 1, 8];

[88] Or, the fault upstream node 5 detects the fault and initiates protection switching. The service route is [3, 4, 5, 4, 3, 2, 1, 8]. The peer sends the alarm information to the source node 3 through the protection ring. After receiving the alarm information, the source node 3 initiates the protection switching. The corresponding switching state in the forwarding table corresponding to the fault LSP is set, and the corresponding service sent by the subsequent source node 3 is according to the forwarding table. The index exchanges labels and forwards them according to the corresponding outbound interface. The route of the service after protection switching is [3, 2, 1, 8].

[89] The protection LSP in the present invention may also be initiated by any node other than the sink node, and its working principle is the same as that of the above protection LSP, but the protection scope is different.

[90] For example, in the ring topology shown in FIG. 3, if the protection LSP is initiated from the node 5, the failure occurring from the downstream link of the node 6 to the sink node cannot be protected, but at the maximum, Protect the fault between the source point and the node 6.

[91] Although the scope of protection is not the largest, this method has certain practical significance due to the different requirements of the protection range in the actual protection LSP application.

The present invention also provides a system for implementing fast re-routing in an MPLS network, which is set in an MPLS network, and the system can establish a corresponding protection LS P for the working LSPs already established in the MPLS network to achieve fast Re-routing protection, the specific implementation structure includes a set of node devices set on the topology ring. The specific structure of each node device is as shown in FIG. 5, including:

[93] (1) Source node determination unit

[94] a source node for determining a protection LSP, that is, each non-sink node that sets a working LSP is used to receive according to the reception. Determining the source node information of the protection LSP, determining the node device as the source node of the protection LSP; or determining the node device in the working LSP ring as the source node of the protection LSP according to the configured information;

[95] When it is determined that it is the source node of the protection LSP, it triggers its own protection LSP establishment unit;

[96] (2) Protection LSP establishment unit

[97] for using a node on the working LSP as a source node for protecting the LSP, and establishing a protection LSP between the working node and the working LSP sink node in the opposite direction from the working node;

[98] The source node that protects the LSP is responsible for initiating the establishment process, and the node devices on the other protection LSPs are responsible for performing the process of establishing the protection LSP;

[99] (3) Protection Processing Unit

[100] It is used to protect the working LSP with the established protection LSP to achieve fast reroute protection after the working LSP fails.

[101] It can be seen that the foregoing system is mainly composed of each node device disposed on the topology ring. The specific implementation structure of the corresponding node device that can implement fast re-routing will be described below with reference to FIG. 5, and the node device is described below. The node device that protects the LSP source node, or the node device that protects the LSP intermediate node, that is, the node device is any node device on the topology ring, and the specific structure includes a protection LSP establishing unit and a protection processing unit, where

[102] (1) The protection LSP establishing unit specifically includes:

[103] The protection LSP establishment operation unit is configured to send or forward a protection LSP establishment message to the sink node of the working LSP in a direction opposite to the protection ring of the working LSP, and the node device that is the source node of the protection LSP needs to initiate the establishment process, That is, the message that the protection LSP is established needs to be sent, and the node device that is the intermediate node that protects the LSP is responsible for forwarding the message established by the protection LSP to establish a corresponding protection LS P;

[104] A protection LSP establishment confirmation unit is configured to receive a protection LSP establishment response message returned by the sink node of the working LSP, and determine a protection LSP establishment.

[105] (2) The protection processing unit specifically includes:

[106] When it is determined that the local node device is the PLR upstream of the fault, the protection switching is directly initiated, and/or the node upstream of the fault sends an alarm to the source node of the working LSP, so as to initiate the protection switching by the source node of the working LSP. The specific protection switching implementation process has been described above, so it will not be described in detail here; [107] For the node device in which the protection switching occurs (which may be the PLR node device upstream of the fault and/or the source node device of the working LSP), the received service is exchanged according to the index of the forwarding table, and is forwarded according to the corresponding outgoing interface. To achieve protection of working LSPs.

[108] Moreover, the node device of the present invention may further include a forwarding relationship storage unit for using the protection LS

After the P is established, the forwarding relationship between the working LSP and the protection LSP is saved. The forwarding relationship is used for protection switching.

The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and any person skilled in the art can easily think of within the technical scope disclosed by the present invention. Changes or substitutions are intended to be included within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

[1] A method for implementing fast rerouting in an MPLS network, which is characterized in that:

On the ring topology of the multi-protocol label switching MPLS network, the node on the working LSP is used as the source node for protecting the LS P, and the protection LSP between the working LSP and the working LSP is established from the source node in the opposite direction of the working LSP. The protection LSP implements fast reroute protection for working LSPs.

[2] The method according to claim 1, wherein the establishing process of the protection LSP includes:

Adding a protection LSP attribute including a ring protection requirement to the message that the source node sends the working LSP to the sink node; after receiving the message, the node of the working LSP other than the sink node is protected by the protection LSP attribute. The source node initiates protection between the sink nodes establishing the working LSP

[3] The method according to claim 1, wherein the establishing process of the protection LSP includes:

The source node of the protection LSP sends a protection LSP establishment message to the sink node of the working LSP along the guard ring opposite to the working LSP on the guard ring;

Each node that receives the protection LSP setup message on the guard ring forwards the protection LSP setup message to the sink node of the working LSP;

The sink node of the working LSP replies to the protection LSP establishment response message to the source node of the protection LSP, and establishes a protection LSP between the sink node of the working LSP and the source node of the protection LSP.

[4] The method according to claim 1, 2 or 3, wherein the method further includes: determining the process of protecting the source node of the LSP, specifically:

In the process of establishing the working LSP, the source node information of the protection LSP is carried by the non-sinking node of the working LSP, and the source node information of the protection LSP is obtained by the source node in the response message sent by the source node or the response message sent by the sink node. Determining the source node that protects the LSP;

Or,

Configure a fixed node in the working LSP to protect the source node of the LSP.

[5] The method according to claim 4, wherein the determining the source node of the protection LSP comprises: using a second hop from a sink node to a source node in a working LSP as a location The source node that protects the LSP.

[6] The method according to claim 1, 2 or 3, wherein in the establishing process of the protection LSP, determining, respectively, the local repair nodes PLR in the protection LSP, and establishing protection on each local repair node The LSP is bound to the forwarding relationship between the working LSP and the protection LSP.

[7] The method according to claim 6, wherein if the working LSP fails, the processing for implementing fast reroute protection on the working LSP includes:

The PLR upstream of the fault initiates the protection switching, and sets the corresponding switching state in the forwarding table corresponding to the working LSP. After the corresponding service received by the PLR upstream of the fault, the corresponding label is forwarded according to the index switching label of the forwarding table and the corresponding outgoing interface.

Or,

The node upstream of the fault sends the alarm information to the source node of the working LSP. The source node initiates the protection switching, and sets the corresponding switching state in the forwarding table corresponding to the working LSP. After that, the source node exchanges labels according to the index of the forwarding table. The corresponding outbound interface forwards the corresponding service;

Or,

The PLR node in the upstream of the fault initiates the protection switching, and sends the alarm information to the working LSP source node. The source node also initiates the protection switching. Before the protection switching initiated by the source node is established, the service is rerouted and forwarded by the PLR upstream of the fault. After the protection switching initiated by the source node is established, the source node reroutes the service.

[8] 8. A node device for implementing fast rerouting, comprising:

The protection LSP establishing unit is configured to: in the MPLS network, a node on the working LSP as a source node for protecting the LS P, and a protection LSP between the local and working LSP sink nodes in a reverse direction of the working LSP; and a protection processing unit, configured to utilize The protection LSP established by the protection LSP establishment unit implements fast reroute protection for the working LSP.

[9] The node device according to claim 8, wherein the protection LSP establishing unit comprises:

a protection LSP establishment operation unit, configured to send or forward a protection LSP establishment message to a sink node of the working LSP in a protection ring direction opposite to the working LSP;

a protection LSP establishment confirming unit, configured to receive a protection LSP established by the sink node of the working LSP The message should be determined to establish a protection LSP.

[10] The node device according to claim 8 or 9, wherein the node device further includes a forwarding relationship storage unit, configured to save the bound working LSP and protection after the protection LSP is established. Forwarding relationship of LSPs.

[11] 11. A system for implementing fast rerouting in an MPLS network, comprising:

The protection LSP establishment unit is set in each node of the ring topology of the MPLS network and is used to work.

The node on the LSP acts as the source node of the protection LSP, and establishes a protection LSP between the working node and the working LSP sink node in the opposite direction from the working node.

The protection processing unit is configured in multiple nodes of the ring topology, and is configured to protect the working LSP by using the established protection LSP to implement fast reroute protection after the working LSP fails.

[12] The system according to claim 11, wherein the system further includes a source node determining unit, configured to determine a source node that protects the LSP, specifically:

The non-sinking node of the working LSP determines the node device that is the source node of the protection LSP according to the source node information of the protected LSP, or determines the node that is the source node of the protection LSP in the working LSP ring according to the configured information. device.