CN102148694A - Linear 1-to-N protection method, device and system for packet transport network - Google Patents

Abstract

The invention discloses a linear 1:N protection method and device for a packet transmission network, which can notify the remote node to perform 1:N protection switching for the working path after the destination node detects that the working path fails; the remote node According to the working path situation detected by itself and the notification from the destination node, determine the working path to perform 1:N protection switching and perform protection switching and notify the destination node that the working path of the protection switching has been executed; The notification of the node is to perform 1:N protection switching on the working path on which the remote node has performed protection switching. The method and device of the invention can realize the linear 1:N protection of the packet transmission network and save the bandwidth. The title of the present invention is a linear 1:N protection method, device and system for packet transmission network.

Description

A linear 1:N protection method, device and system for packet transmission network

technical field

The present invention relates to communication technology, in particular to a linear 1:N protection method, device and system for a packet transmission network.

Background technique

With the continuous development of packet transport network (PTN) technology, PTN will gradually become the main access technology of various network operators. The PTN defined now includes but is not limited to the following networks: MPLS, T-MPLS, MPLS-TP, Ethernet, etc., and its network protection is of great significance.

RFC5654 proposes that MPLS-TP must support pseudowire (pseudowire, PW) and label switching path (label switching path, LSP) point-to-point (point to point, P2P) bidirectional 1:N linear protection switching, must support point-to-multipoint ( point to multi point, P2MP) unidirectional 1:N protection switching.

Among them, unidirectional protection means that only the services in the affected direction are switched; bidirectional means that services in both directions are switched; 1:N protection means that one protection path protects N working paths, and the bandwidth of the protection path must be at least Greater than or equal to the bandwidth of the path with the largest bandwidth among the N working paths, which is mostly used for branch signal and equipment board-level protection.

For 1:N protection, since the probability that N working paths or equipment boards fail at the same time is very low, network resources can be effectively used, but the cost is that the protection switching time is slower than that of the 1:1 protection scheme.

In the currently defined 1:1 protection scheme, the first and last nodes of the working path and the protection path are configured with a Protection State Coordination (PSC) protocol. When the working path fails, the node that detects the failure switches the traffic to on the protection path, and sends an APS protection switching signaling to the remote end of the path, and the remote end also switches the traffic to the protection path after receiving the protection switching signaling.

Although the above-mentioned 1:1 protection scheme only needs to exchange signaling messages once between the first and last nodes to complete the switchover, the bandwidth is seriously wasted.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a linear 1:N protection method and device for a packet transmission network, so as to realize the linear 1:N protection of a packet transmission network and save bandwidth.

Another object of the present invention is to provide a linear 1:N protection system for a packet transmission network, so as to realize the linear 1:N protection of the packet transmission network and save bandwidth.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A linear 1:N protection method for a packet transmission network, the method comprising:

After the destination node detects that the working path fails, it notifies the remote node to perform 1:N protection switching for the working path;

The remote node determines the working path to perform 1:N protection switching according to the working path situation detected by itself and the notification from the destination node, and performs protection switching and notifies the destination node that the working path of the protection switching has been executed;

The destination node performs 1:N protection switching on the working path on which the remote node has performed protection switching according to the notification from the remote node.

Further includes:

The request for indicating 1:N protection switching and the content of the protection switching command indicating a specific working path are expanded in advance.

The method for the remote node to determine the working path to perform the 1:N protection switching is as follows:

The remote node itself does not detect the failure of the working path, and bridges the traffic of the receiving end and the sending end of the working path notified by the destination node to the protection path on its own side;

Or, the remote node itself detects a working path failure, and compares the priority of the working path that it detects the failure with the working path notified by the destination node, and then sends the receiving end of the working path with the highest priority to the The sender traffic is bridged to the protection path.

The pre-extended content of the protection switching command is included in the two-phase protection state coordination (2-phase PSC) protocol format.

The request flag bit used to indicate 1:N protection switching is: protection switching request (Reverse request) flag bit;

The content indicating the specific working path is: working path number.

A linear 1:N protection device for a packet transmission network, the device is used as a remote node, including a 1:N protection switching unit and a communication unit; wherein,

The communication unit is configured to receive a message from the destination node performing a 1:N protection switching unit, and send it to the 1:N protection switching unit; and notify the destination node according to the triggering of the 1:N protection switching unit The specific protection switching situation;

The 1:N protection switching unit is used to bridge the traffic of the receiving end and the sending end of the working path corresponding to the above notification received on the side of the node to which it belongs to the protection path, and notify the communication unit of the situation .

It further includes a fault detection unit, which is used to detect the status of the working path of an instance of the node to which it belongs, and notify the 1:N protection switching unit when a working path fault is detected;

The 1:N protection switching unit is further used to compare the priority of the working path corresponding to the notification of the fault detection unit and the working path corresponding to the message from the destination node, and set the highest priority on the side of the node to which it belongs. Both the receiving end and the sending end traffic of the working path are bridged to the protection path.

The communication unit is provided with a pre-expanded request flag for indicating 1:N protection switching and the protection switching command content indicating a specific working path, which is included in the 2-phase PSC protocol format;

The request flag bit used to indicate 1:N protection switching is: Reverse request flag bit; the content indicating the specific working path is: working path number.

A linear 1:N protection device for a packet transmission network, as a destination node, the device includes a fault detection unit, a 1:N protection switching unit, and a communication unit; wherein,

The failure detection unit is configured to detect the status of the working path on the side of the node to which it belongs, and notify the communication unit when a working path failure is detected;

The communication unit is used to send the fault condition of the working path from the fault detection unit to the remote node; also receive a message from the remote node indicating to perform 1:N protection switching, and send the message to the 1:N protection switching unit; and notifying the remote node of the completion of protection switching from the 1:N protection switching unit;

The 1:N protection switching unit is used to bridge the receiving end and the sending end traffic of the working path corresponding to the received message indicating 1:N protection switching to the protection path on the side of the node to which it belongs, Then notify the communication unit of the fact that the protection switching is completed.

The communication unit is provided with a pre-expanded request flag for indicating 1:N protection switching and the protection switching command content indicating a specific working path, which is included in the 2-phase PSC protocol format;

The request flag bit used to indicate 1:N protection switching is: Reverse request flag bit; the content indicating the specific working path is: working path number.

A linear 1:N protection system for a packet transmission network, the system includes a remote node and a destination node; wherein,

The remote node is used to notify the 1:N protection switching according to the working path detected by itself and the instruction from the destination node, determine the working path to be 1:N protection switching and perform the protection switching, and also notify the destination node The node executes the working path of the protection switching;

The destination node is used to notify the remote node to perform 1:N protection switching for the working path after detecting that the working path fails; and according to the notification from the remote node, the remote node has performed protection switching 1:N protection switching is performed on the working path.

The system is provided with a pre-expanded request flag bit for indicating 1:N protection switching, and a protection switching command content indicating a specific working path, which is included in the 2-phase PSC protocol format;

The request flag bit used to indicate 1:N protection switching is: the protection switching request Reverse request flag bit; the content indicating the specific working path is: the working path number.

It can be seen that the linear 1:N protection method, device and system of the packet transmission network of the present invention can expand the content of the protection switching command, add the 1:N protection switching request flag bit, and the number of the working path; the destination node detects that the working path fails Finally, notify the remote node to perform 1:N protection switching for the working path; the remote node determines the working path to perform 1:N protection switching and performs protection switching according to the working path conditions detected by itself and the notification from the destination node , notifying the destination node of the working path on which the protection switching has been performed; the destination node performs 1:N protection switching on the working path on which the remote node has performed protection switching according to the notification from the remote node. Therefore, the linear 1:N protection of the packet transmission network can be realized smoothly.

Description of drawings

Fig. 1 is the schematic diagram of the 1-phase PSC protocol format of prior art;

Fig. 2 is the 2-phase PSC protocol format schematic diagram of the present invention;

FIG. 3 is a schematic diagram of 1:N protection switching according to Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of 1:N protection switching in Embodiment 2 of the present invention;

Fig. 5 is a schematic diagram of the 1:N protection switching process of the present invention;

Fig. 6 is a diagram of the 1:N protection switching device of the present invention.

Detailed ways

Referring to FIG. 1, FIG. 1 is a schematic diagram of the format of a 1-phase protection state coordination (Protection state coordination, PSC) protocol in the prior art. The 1-phase PSC protocol format shown in Figure 1 includes the following:

(1) Ver is the version of the 1-phase PSC protocol, usually set to 0;

(2) The request (Request) flag is used to indicate the command request for protection switching. The currently defined commands are as follows:

(1111) Clear clear;

(1110) Lockout protection protection lock;

(1101) Forced switch forced switching;

(0110) Signal fault signal failure;

(0101) Signal degrade signal degradation;

(0100) Manual switch manual switching;

(0011) Wait to restore to wait for recovery;

(0010) Do not revert (DNR) non-reversal;

(0000) No request empty request;

(3) Typ is the type of protection switching, and the currently defined types are as follows:

11: 1+1 bidirectional switching 1+1 bidirectional protection switching;

10:1:1 bidirectional switching 1:1 bidirectional protection switching;

01: 1+1 unidirectional switching 1+1 unidirectional protection switching;

00:1:1 unidirectional switching 1:1 unidirectional protection switching;

(4) FPath and Path indicate the traffic conditions on the failed path and the currently activated path respectively:

Fpath: When the value is 0, it indicates that the protection path is faulty; when the value is 1, it indicates that the working path is faulty, and other flag bits are reserved.

Path: When the value is 0, it indicates that the traffic is currently passing on the working path; when the value is 1, it indicates that the traffic is currently passing on the protection path, and the rest of the flag bits are reserved.

(5) Reserved is a reserved flag, to be used for expansion.

In practical applications, the content of the protection switching command can be extended, such as adding a 1:N protection switching request flag and a working path number, so that the extended protection switching command can provide technical support for the 1:N protection switching. Specifically, the extension of the content of the protection switching command can be realized by extending the automatic protection switching protocol (Automatic Protection Protocol, APS), PSC and other protocol formats. Figure 2 shows an extension method by taking PSC as an example.

Referring to Fig. 2, Fig. 2 is a schematic diagram of the 1-phase PSC protocol format of the present invention, and Fig. 2 defines a 2-phase PSC protocol for 1:N protection switching on the basis of the content shown in Fig. 1 . The specific extensions are as follows:

(1) A new Request flag is defined at the Request flag:

(0001) Reverse request protects a command of the switching request and requests recovery;

You can set the priority for the Reverse request command, for example: set the priority of the Reverse request command higher than Do not revert, but lower than Wait to restore. If a node receives two or more protection switching request commands at the same time, the protection switching request command with the highest priority is valid.

(2) The 10 and 00 flags of the original protection type are two-way and one-way 1:1 protection switching respectively. Now this definition needs to be slightly expanded, and the meaning is expanded to two-way and one-way 1:N protection switching;

(3) Use the Reserved byte to define a 4-bit path number (path number, PN) flag for numbering the path. If it is extended 4bits, then a protection path can protect up to 14 working paths; if one protection path needs to protect more working paths, you can define more bits of PN flags, here is just 4bits as an example, But not limited to 4bits.

Specifically, a value of 0 is used to identify a protection path, a value of 1 to 14 is used to identify a working path, and a value of 15 indicates that there is an additional service in the current protection channel. The size of the path number indicates the priority of protection switching for the path; under the same circumstances, the smaller the path number, the higher the priority. That is: if a signal failure occurs on working path 1 and working path 2 at the same time, working path 1 will be protected first.

When applying the above extended structure to perform 1:N protection switching, the first and last nodes of the path can complete the 1:N protection switching action through only two signaling interactions (not included in the No request request), so multiple When the working path fails at the same time, it realizes 1:N protection and recovery of the data packet service. The basic idea of 1:N protection switching is as follows:

After the destination node detects a fault in the working path (this fault can be signal failure or signal degradation), it sends a PSC message for protection switching to the remote node; which can carry the cause of the fault, the failed working path and Information such as the traffic condition on the currently activated path, the number of the failed working path, etc.

The remote node receives the protection switching command from the destination node, and determines the working path for 1:N protection switching in combination with the working path conditions detected by itself. For example, when the remote node only receives a protection switching command from the destination node, the remote node determines to perform 1:N protection switching on the working path corresponding to the protection switching command; When the protection switching command of the destination node detects that the working path on its own side is faulty, the remote node can compare the working path corresponding to the received protection switching command with the priority of the working path that has failed on its own side, and Make sure to perform 1:N protection switching on the working path with the highest priority.

Afterwards, the remote node performs a protection switching action on the working path that has been determined to perform 1:N protection switching, and then sends a Reverse Request command to the destination node, which contains the failed working path and the traffic conditions on the currently activated path, and the Information such as the serial number of the working trail that completes the protection switching.

The destination node receives the Reverse Request command from the remote node, and performs protection switching on the working path corresponding to the command on its own side; then sends a No Request message to the remote node, which contains the failed working path and the current active path. information such as the traffic condition on the path, the number of the working path that has completed the protection switching, etc.

When performing 1:N protection switching based on the above basic idea, the specific operation process can be shown in Figures 3 and 4.

Referring to FIG. 3 , FIG. 3 is a schematic diagram of 1:N protection switching according to Embodiment 1 of the present invention. In Figure 3, a 1:N protection group is configured between node A (NE A) and node B (NE B), in order to apply one protection path to protect N working paths. NE A and NE B are the common first and last nodes of these N+1 paths, and they can be directly connected, or they can span multiple nodes in the middle.

Generally speaking, the above N+1 paths belong to different Shared Risk Link Groups (SRLGs), for example, they are in different optical fibers. In this way, only one path will be affected when an optical fiber cut accident occurs, instead of It will cause N+1 paths to be unusable. The protection trail is numbered 0, and the working trails are numbered from 1 to N in sequence. At a certain moment, a signal failure occurs in the direction of working path 1 from NE A to NE B, then the process of performing 1:N protection switching is as follows:

NE B detects a signal failure through the CV (connectivity verification) OAM running on working path 1. Specifically, since the sending frequency of CV used for protection switching is generally 3.3ms, if three of the CV messages sent from NE A to NE B are not received, then NE B will consider that there is a signal failure in its upstream, so NE B can detect link signal failure within 10ms. NE B sends a PSC message with the command SF (signal fault) to NE A, where Fpath＝01 indicates that a signal failure occurs in the working path, path＝00 indicates that the traffic is currently being transmitted on the working path, and PN＝01 indicates that a signal occurs in working path 1 invalidated.

After NE A receives the PSC message from NE B, it bridges the traffic of the receiving end and the sending end of working path 1 to the protection path on its own side, and then sends a PSC message with the command RR (ReverseRequest) to NE B, Fpath＝01 in the PSC message indicates that the working path has a signal failure, path＝01 indicates that the traffic has been bridged to the protection path at the NE A end, and PN＝01 indicates that the NE A end is bridged to the protection path. The path is working path 1.

After NE B receives the Reverse Request from NE A, it bridges the traffic of the receiving end and the sending end of working path 1 to the protection path on its own side, and then sends a PSC message with the command empty request NR (Norequest) to NE A. Fpath=01 in the PSC message indicates that the working path has a signal failure, path=01 indicates that the traffic has been bridged to the protection path at the NE B end, and PN=01 indicates that the NE B end is bridged to the working path on the protection path For the working path 1.

Referring to FIG. 4, FIG. 4 is a schematic diagram of 1:N protection switching according to Embodiment 2 of the present invention. In Figure 4, a 1:N protection group is configured between NE A and NE B, so that one protection path can be used to protect N working paths. NE A and NE B are the common first and last nodes of these N+1 paths, and they can be directly connected, or they can span multiple nodes in the middle. In general, N+1 paths belong to different SRLGs. The number of the protection path is 0, and the number of the working path is sequentially from 1 to N; and, at time t1, a signal failure occurs on the working path 2 in the direction from NE B to NE A.

In this case, NE A detects the signal failure through CV OAM, and then sends a PSC message with the command SF. In the PSC message, Fpath=01 indicates that the signal failure occurs on the working path, and path=00 indicates that the traffic is currently on the working path. In the upper transmission, PN=10 indicates that the signal failure occurs in the working path 2.

After NE B receives the PSC message from NE A with the command signal fault, NE B detects that the signal fault also occurs in the direction from NE A to NE B on working path 1. At this time, NE B compares the priorities of working path 1 and working path 2, and determines that working path 1 has the highest priority, and then bridges the traffic of working path 1 to the protection path on its own side. After that, NE B sends a PSC message with the command Reverse Request to NE A. Fpath=1 in the PSC message indicates that the working path is faulty, path=01 indicates that the traffic has been bridged to the protection path on the NE B side, and PN= 01 indicates that the working path bridged to the protection path at the NE B end is working path 1.

After NE A receives the Reverse Request from NE B, it bridges the traffic of the receiving end and the sending end of working path 1 to the protection path on its own side, and then sends a PSC message with the command No request to NE B. The PSC Fpath＝01 in the message indicates that the working path has a signal failure, path＝01 indicates that the traffic has been bridged to the protection path at the NE A end, and PN＝01 indicates that the working path bridged to the protection path at the NE A end is working path 1 .

It can be seen from the above description that the operation process in Fig. 3 and Fig. 4 can be simplified as shown in Fig. 5 . Referring to Fig. 5, Fig. 5 is a schematic diagram of the 1:N protection switching process of the present invention, and the process includes the following steps:

Step 510: Expand the content of the protection switching command, adding Reverse Request and working path number required by the 1:N protection switching request.

Step 520: After the destination node detects that the working path fails, it notifies the remote node to perform 1:N protection switching for the working path.

Step 530: The remote node determines the working path to perform 1:N protection switching according to the working path detected by itself and the notification from the destination node, executes the protection switching, and notifies the destination node that the protection switching has been performed on the working path .

Step 540: According to the notification from the remote node, the destination node performs 1:N protection switching on the working path on which the remote node has performed protection switching.

In order to smoothly realize the 1:N protection switching operation in each of the above figures, settings as shown in FIG. 6 can be performed. Referring to Fig. 6, Fig. 6 is a diagram of a 1:N protection switching device of the present invention; as an NE, the device includes a connected fault detection unit, a 1:N protection switching unit, and a communication unit; these functional entities can be connected sequentially or in pairs , as long as they can interact normally to realize 1:N protection switching smoothly. Moreover, the communication unit is provided with a protection switching command format that has realized content expansion, so operations such as encapsulation, analysis, and transmission of communication content can be performed during normal communication.

In specific applications, when the above-mentioned NE is used as a remote node, the communication unit therein can receive the PSC message of the protection switching command (such as signal fault) from the destination node, and send the received PSC message to the 1:N The protection switching unit bridges the receiving end and the sending end traffic of the working path corresponding to the above-mentioned PSC message received by the 1:N protection switching unit to the protection path on the side of the node to which it belongs, and notifies the situation to communication unit. The communication unit sends a PSC message whose command is Reverse Request to the destination node according to the notification of the 1:N protection switching unit, so as to notify the destination node of the specific protection switching situation.

It should be noted that the fault detection unit can detect the status of the working path on the side of the node to which it belongs, and notify the 1:N protection switching unit when detecting a fault in the working path. If the working path corresponding to the notification of the fault detection unit is different from the working path corresponding to the above-mentioned PSC message from the destination node, the 1:N protection switching unit needs to compare the priorities of the two working paths , and bridge the traffic of the receiving end and the sending end of the working path with the highest priority to the protection path on the side of the node to which it belongs, and then apply the aforementioned method to notify the destination node of the situation through the communication unit.

In addition, when the above-mentioned NE is used as the destination node, the fault detection unit can detect the status of the working path on the side of the node to which it belongs, and notify the communication unit when it detects that there is a working path, and the communication unit sends the situation in the form of a PSC message sent to the remote node. Moreover, the communication unit can also receive the PSC message whose command is Reverse Request from the remote node, and send the PSC message to the 1:N protection switching unit, and the 1:N protection switching unit will transmit the PSC message on the side of the node to which it belongs. Both the receiving end and the sending end traffic of the working path corresponding to the above PSC message are bridged to the protection path, and then the communication unit is notified of the completion of the protection switching, and the communication unit sends the command to the remote node to the PSC with No request message to notify the remote node that the protection switching has been completed.

To sum up, it can be seen that the linear 1:N protection technology of the packet transmission network of the present invention can successfully realize the linear 1:N protection of the packet transmission network no matter it is a method, a device embodied by a node, or a system including a node.

The above description is only a preferred embodiment of the present invention, and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the within the protection scope of the present invention.

Claims (12)

1. A linear 1: N protection method for a packet transport network, the method comprising:

after detecting that the working path has a fault, the destination node informs the remote node to carry out 1: N protection switching on the working path;

the remote node determines a working path to be subjected to 1: N protection switching according to the working path condition detected by the remote node and the notification from the destination node, executes the protection switching and notifies the destination node of the working path to execute the protection switching;

and the destination node performs 1: N protection switching on the working path on which the protection switching has been performed by the remote node according to the notification from the remote node.

2. The method of claim 1, further comprising:

the request for indicating 1: N protection switching and the protection switching command content indicating the specific working path are pre-expanded.

3. The method of claim 2, wherein the method for the remote node to determine the working path to be subjected to the 1: N protection switching comprises:

the remote node does not detect the working path fault, and bridges the flow of a receiving end and a sending end of the working path informed by the destination node to a protection path at one side of the remote node;

or the remote node detects the working path fault, compares the working path detected with the fault with the priority of the working path notified by the destination node, and bridges the receiving end and sending end traffic of the working path with the highest priority to the protection path on one side of the remote node.

4. The method according to claim 2 or 3, wherein the pre-expanded protection switching command content is contained in a two-phase protection state coordination 2-phase PSC protocol format.

5. The method of claim 4,

the request flag bits for indicating 1: N protection switching are: a protection switching request Reverse request flag bit;

the content indicating a specific work path is: the working path number.

6. A linear 1: N protection device of a packet transport network is characterized in that the device is used as a far-end node and comprises a 1: N protection switching unit and a communication unit; wherein,

the communication unit is used for receiving a message from a destination node for carrying out the 1: N protection switching unit and sending the message to the 1: N protection switching unit; informing the specific protection switching condition of a target node according to the triggering of the 1: N protection switching unit;

and the 1: N protection switching unit is used for bridging the flow of the receiving end and the flow of the sending end of the working path corresponding to the received notification to the protection path on the node side of the 1: N protection switching unit and notifying the communication unit of the situation.

7. The apparatus according to claim 6, further comprising a failure detection unit, configured to detect a working path state on a side of a node to which the failure detection unit belongs, and notify the 1: N protection switching unit when detecting that there is a working path failure;

the 1: N protection switching unit is further configured to compare priorities of a working path corresponding to the notification of the fault detection unit and a working path corresponding to the message from the destination node, and bridge, on a node side to which the working path with the highest priority is connected to the protection path, traffic of a receiving end and a sending end of the working path.

8. The apparatus according to claim 6 or 7, wherein a pre-expanded request flag bit for indicating 1: N protection switching and protection switching command content indicating a specific working path are set in the communication unit, and the content is included in a 2-phase PSC protocol format;

the request flag bits for indicating 1: N protection switching are: a Reverse request flag bit; the content indicating a specific work path is: the working path number.

9. A linear 1: N protection device of a packet transport network is characterized in that the device is used as a destination node and comprises a fault detection unit, a 1: N protection switching unit and a communication unit; wherein,

the fault detection unit is used for detecting the working path state of one side of the node to which the fault detection unit belongs and informing the communication unit when the fault of the working path is detected;

the communication unit is used for sending the working path fault condition from the fault detection unit to a remote node; receiving a message indicating 1: N protection switching from a remote node, and sending the message to the 1: N protection switching unit; and notifying the far-end node of the completion of the protection switching from the 1: N protection switching unit;

the 1: N protection switching unit is configured to bridge, at a node side to which the 1: N protection switching unit belongs, traffic of a receiving end and a sending end of a working path corresponding to a received message indicating that the 1: N protection switching is performed to the protection path, and then notify the communication unit of the situation of completing the protection switching.

10. The apparatus of claim 9, wherein a pre-expanded request flag bit for indicating 1: N protection switching and protection switching command content indicating a specific working path are set in the communication unit, and the content is included in a 2-phase PSC protocol format;

the request flag bits for indicating 1: N protection switching are: a Reverse request flag bit; the content indicating a specific work path is: the working path number.

11. A linear 1: N protection system of a packet transport network is characterized by comprising a remote node and a destination node; wherein,

the remote node is used for notifying 1: N protection switching according to the working path condition detected by the remote node and an instruction from a target node, determining the working path to be subjected to the 1: N protection switching, executing the protection switching, and notifying the target node of the working path to be subjected to the protection switching;

the destination node is used for informing the remote node to carry out 1: N protection switching on the working path after detecting that the working path has a fault; and performing 1: N protection switching on the working path of which the protection switching has been performed by the remote node according to the notification from the remote node.

12. The system of claim 11, wherein a pre-expanded request flag bit for indicating 1: N protection switching and protection switching command content indicating a specific working path are set in the system, and the content is included in a 2-phase PSC protocol format;

the request flag bits for indicating 1: N protection switching are: a protection switching request Reverse request flag bit; the content indicating a specific work path is: the working path number.

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