WO2011095101A1

WO2011095101A1 - Linear 1: n protection method, device and system for packet transport network

Info

Publication number: WO2011095101A1
Application number: PCT/CN2011/070666
Authority: WO
Inventors: 张飞; 代雪会; 吴波
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-02-04
Filing date: 2011-01-26
Publication date: 2011-08-11
Also published as: CN102148694B; CN102148694A

Abstract

A linear 1: N protection method, device and system for a packet transport network are provided. In the packet transport network, once a destination node detects that a fault has occurred in a working path, it can notify a remote node to carry out a 1: N protection switching for the working path; the remote node determines the working path for which the 1: N protection switching will be carried out according to the working path situation detected by the remote node and the notification from the destination node, and hereby performs the protection switching and informs the destination node the working path for which said protection switching has been carried out; according to the notification from the remote node, the destination node carries out the 1:N protection switching for said working path for which the remote node has performed the protection switching. The method, device and system can realize the linear 1: N protection for the packet transport network and save the bandwidth.

Description

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

The present invention relates to communication technologies, and in particular to a linear 1 : N protection method, apparatus 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 PTNs defined now include, but are not limited to, the following networks: MPLS, T-MPLS, MPLS-TP, Ethernet, etc., and their network protection is of great significance.

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

The one-way protection refers to switching only the services in the affected direction; the two-way is that the services in both directions are switched; 1: N protection means that one protection path protects N working paths, and the protection path has at least the bandwidth. The bandwidth of one path with the largest bandwidth among the N working paths is used for the protection of the tributary signal and the device board level.

For the 1:N protection, the network resources can be effectively utilized because the probability of N working paths or device boards failing at the same time is low, but the cost is that the protection switching time is slower than 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 to the far end of the path The APS protection switching signaling is sent, and the remote end also switches the traffic to the protection path after receiving the protection switching signaling.

Although the above 1 : 1 protection scheme only needs to exchange the signaling message by the first and last nodes to complete the handover, the bandwidth waste is serious. Summary of the invention

In view of this, the main object of the present invention is to provide a linear 1 : N protection method and apparatus for a packet transmission network to implement linear 1 : N protection of a packet transmission network, thereby saving bandwidth.

Another object of the present invention is to provide a linear 1 : N protection system for a packet transport network to achieve linear 1 : N protection of a packet transport network, saving bandwidth.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

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

In the packet transmission network, after detecting that the working path is faulty, the destination node notifies the remote node to perform 1:N protection switching for the working path;

The remote node determines, according to the detected working path condition and the notification from the destination node, the working path to perform the 1:N protection switching, and performs the protection switching according to the notification and notifies the destination node to perform the working path of the protection switching;

The destination node performs a 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.

The method further includes:

The request flag bit indicating the 1:N protection switching and the content of the protection switching command indicating the specific working path are pre-expanded.

The process of determining the working path for performing the 1:N protection switching includes:

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

Or, the remote node itself detects the working path failure and compares the failure detected by itself. The working path and the working path notified by the destination node are prioritized, and then the receiving end and the transmitting end of the working path with the highest priority are bridged to the protection path on the own side.

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

The request flag for indicating 1 : N protection switching is: protection switching request Reverse request flag bit;

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

A linear 1 : N protection device of a packet transmission network, in a packet transmission network, the device as a remote node, including a 1:N protection switching unit, a communication unit;

The communication unit is configured to receive a packet from the destination node that performs the 1:N protection switching unit, and send the packet to the 1:N protection switching unit; and notify the destination node according to the triggering of the 1:N protection switching unit. Specific protection switching situation;

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

Further comprising a fault detecting unit, configured to detect a working path state of a node to which the node belongs, and notify the 1:N protection switching unit when a working path fault is detected;

The 1:N protection switching unit is further configured to compare the priority of the working path corresponding to the notification of the fault detecting unit with the working path corresponding to the packet from the destination node, and the highest priority is performed on the node side to which the node belongs. Both the receiving end and the sending end of the working path are bridged to the protection path.

The communication unit 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, the content being included in the 2-phase PSC protocol format;

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

A linear 1:N protection device of a packet transmission network, in a packet transmission network, the device as a destination node, comprising a fault detection unit, a 1:N protection switching unit, and a communication unit; wherein the fault detection unit is configured to Detecting a working path state on a side of the node to which it belongs, and notifying the communication unit when a working path failure is detected;

The communication unit is configured to send a working path fault condition from the fault detecting unit to the remote node; and receive a message from the remote node indicating that the 1:N protection switching is performed, and send the message to the 1 : an N protection switching unit; and notifying the remote node of the completion protection switching from the 1:N protection switching unit;

The 1:N protection switching unit is configured to bridge the receiving end and the sending end of the working path corresponding to the received packet with the 1:N protection switching on the node to which the node belongs to the protection path, The communication unit is notified of the completion of the protection switching.

The request flag for indicating 1 : N protection switching is: Reverse request flag; indicates that the content of the specific working path is: Work path number.

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

The remote node is configured to perform a 1:N protection switching notification according to the detected working path condition and the indication from the destination node, determine a working path to perform 1:N protection switching, and perform protection switching, and notify the purpose. The node performs the working path of the protection switching;

The destination node is configured to notify the remote node to perform 1:N protection switching on the working path after detecting that the working path is faulty; and perform protection switching on the remote node according to the notification from the remote node. The working path is 1:N protection switching. 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, the content is included in the 2-phase PSC protocol format;

The request flag for indicating 1 : N protection switching is: protection switching request Reverse request flag

The content indicating the specific working path is: Work 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 1: N protection switching request flag bit, and work path number; the destination node detects that the working path is faulty. After that, the remote node is notified to perform 1:N protection switching on 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 condition detected by the remote node and the notification from the destination node. And notifying the destination node that the working path of the protection switching is performed; the destination node performs 1:N protection switching on the working path that 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 smoothly implemented. DRAWINGS

1 is a schematic diagram of a format of a 1-phase PSC protocol in the prior art;

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

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

4 is a schematic diagram of a 1:N protection switching according to Embodiment 2 of the present invention;

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

Figure 6 is a diagram of a 1:N protection switching device of the present invention. detailed description

Referring to FIG. 1, FIG. 1 is a schematic diagram of a format of a 1-phase Protection State Coordination (PSC) protocol in the prior art. In 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 command is 3⁄4:

(1111) Clear clear;

(1110) Lockout protection protection lock;

(1101) Forced switch forced switching;

(0110) Signal fault signal is invalid;

(0101) Signal degrade signal degradation;

(0100) Manual switch manual switching;

(0011) Wait to restore waiting for recovery;

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

(0000) No request empty request;

(3) Typ is the type of protection switching. The types currently defined 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 one-way protection switching;

00: 1 : 1 unidirectional switching 1 : 1 one-way protection switching;

(4) FPath and Path respectively indicate the path of the failure and the traffic on the currently activated path:

Fpath: A value of 0 indicates that the protection path is faulty. A value of 1 indicates that the working path is faulty and the remaining flags are reserved.

Path: A value of 0 indicates that the traffic is currently being transmitted on the working path. A value of 1 indicates that the traffic is currently being transmitted on the protection path, and the remaining flags are reserved.

(5) Reserved is reserved flag, which is to be expanded. In the actual application, you can extend the content of the protection switching command, such as: Add 1: N protection switching request flag and working path number, so that the extended protection switching command can provide technical support for 1: N protection switching. Specifically, the content of the protection switching command content can be extended by extending the protocol formats such as Automatic Protection Protocol (APS) and PSC. FIG. 2 shows an extension manner by using PSC as an example.

Referring to FIG. 2, FIG. 2 is a schematic diagram of a 1-phase PSC protocol format according to the present invention. FIG. 2 defines a 2-phase PSC protocol for 1:N protection switching based on the content shown in FIG. Specific expansion:

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

(0001) Reverse request protects a command of the switching request, requesting recovery;

You can set the priority for the Reverse request command, such as: Set the Reverse request command to take precedence over 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 original protection type 10 and 00 flag bits are bidirectional and one-way 1 : 1 protection switching, respectively. Now it is necessary to expand this definition slightly, and the meaning is expanded to two-way and one-way 1: N protection switching;

(3) Using the Reserved byte, define the 4-bit path number (PN) flag, which is used to number the path. If the extension is 4bits, then the protection path of a protection path is protected by a maximum of 14; if more protection paths need to be protected by one protection path, more PN flag bits can be defined. Here, only 4bits is used as an example. But not limited to 4bits.

Specifically, the value 0 is used to identify the protection path, and the value 1 to 14 is used to identify the working path. The value 15 indicates that there is extra service in the current protection channel. The size of the path number indicates the priority of the protection switching for the path. In the same case, the smaller the path number, the higher the priority. That is: if the work path 1 and the work path 2 have a signal failure failure at the same time, then the priority protection work Path 1.

When applying the above-mentioned extended structure for 1:N protection switching, the first and last nodes of the path can complete the 1:N protection switching operation only through two signaling interactions (not counting the No request request) process, so that multiple processes can be processed efficiently When the working path fails at the same time, the 1:N protection and recovery of the packet service is realized. The basic idea of performing 1 : N protection switching is as follows:

After detecting that the working path is faulty (this fault may be a signal failure or a signal degradation), the destination node sends a PSC packet for protection switching to the remote node; the fault may be carried, the failed working path, and Information about the traffic on the currently active path, the number of the failed working path, and so on.

The remote node receives the protection switching command from the destination node, and determines the working path for the 1:N protection switching in combination with the working path detected by itself. For example, if the remote node only receives the 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 of the one 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 is faulty on one side, and Make sure to perform a 1:N protection switching on the highest priority working path.

After that, the remote node performs a protection switching operation on the working path that is determined to perform 1:N protection switching, and then sends a Reverse Request command to the destination node, where the failed working path and the traffic situation on the currently activated path are already Complete the information such as the number of the working path for protection switching.

The destination node receives the Reverse Request command from the remote node, and performs a protection switching action on the working path corresponding to the command on its own side. Then, the No Request message is sent to the remote node, where the failed working path and the currently activated Information about the traffic on the path, the number of the work path that has completed the protection switchover, and so on. Based on the above basic idea, when the 1:N protection switching is performed, 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 ) to protect N working paths with a protection path. NE A and NE B are the first and last nodes common to these N+1 paths, and can be directly connected or spanned in multiple nodes.

In general, the above N+1 paths belong to different shared risk link groups ( SRLG ), such as in different optical fibers, so that when an optical fiber cut occurs, only one path is affected, instead of Will cause N+1 paths to be unusable. The protection path number is 0, and the work path number is from 1 to N. When the working path 1 fails from the direction of NE A to NE B at a certain time, the process of performing 1 : N protection switching is as follows:

NE B detects the signal failure through the CV (connectivity verification) OAM running on the working path 1. Specifically, since the transmission frequency of the CV for protection switching is generally 3.3 ms, if three CV messages sent from the NE A to the NE B are not received, the NE B considers that the upstream signal is invalid. NE B can detect link signal failure within 10ms. NE B sends a PSC message with the command SF (signal fault) to NE A. Fpath=01 indicates that the working path has a signal failure, path=00 indicates that the traffic is currently transmitted on the working path, and PN=01 indicates that the working path 1 has a signal. Invalid.

After receiving the PSC packet from the NE B, the NE A bridges the traffic of the receiving end and the transmitting end of the working path 1 to the protection path on its own side, and then sends a command to restore the requesting RR (Reverse Request) PSC packet. For 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 working path is working path 1.

After receiving the Reverse Request from NE A, NE B bridges the traffic of the receiving end and the transmitting end of working path 1 to the protection path on its own side, and then sends a null request. The PSC message of NR (No request) is sent to NE A. In the PSC message, Fpath=01 indicates that the working path has a signal failure, and path=01 indicates that the traffic has been bridged to the protection path at the NE B end. PN=01 indicates that The working path of the NE B-end bridge connected to the protection path is 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 to protect a N working path by applying a protection path. NE A and NE B are the first and last nodes common to the N+1 paths, and may be directly connected or may 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 from 1 to N; and, at time tl, the path of the working path 2 from NE B to NE A is invalid.

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 working path is invalid, and path=00 indicates that the traffic is currently in the working path. Passed on, PN=10 indicates that signal failure occurs in working path 2.

When NE B receives the PSC message from NE A with the signal fault, NE B detects that the working path 1 has a signal failure from NE A to NE B. 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. Afterwards, NE B sends a PSC message with the reverse request to NE A. In the PSC message, Fpath=l indicates that the working path is faulty. Path=01 indicates that the traffic is bridged to the protection path on the NE B side. PN= 01 indicates that the working path on the NE B end bridge connected to the protection path is the working path 1.

After receiving the Reverse Request from NE B, NE A bridges the traffic of the receiving end and the transmitting end of working path 1 to the protection path on its own side, and then sends a PSC message with the request No request to NE B. The PSC In the message, Fpath=01 indicates that the working path has a signal failure. Path=01 indicates that the traffic has been bridged to the protection path on the NE A end. PN=01 indicates that the working path on the NE A end bridged to the protection path is the working path. . As can be seen from the above, the operation of FIGS. 3 and 4 can be simplified as shown in FIG. 5. Referring to FIG. 5, FIG. 5 is a schematic diagram of a 1:N protection switching process according to the present invention, where the process includes the following steps:

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

Step 520: After detecting that the working path is faulty, the destination node notifies the remote node to perform a 1:N protection switching for the working path.

Step 530: The remote node determines, according to the detected working path condition and the notification from the destination node, the working path to perform the 1:N protection switching and performs protection switching, and notifies the destination node to perform the working path of the protection switching. .

Step 540: The destination node performs a 1:N protection switching on the working path that the remote node has performed protection switching according to the notification from the remote node.

In order to smoothly implement the 1:N protection switching operation in each of the above figures, the setting as shown in Fig. 6 can be performed. Referring to FIG. 6, FIG. 6 is a diagram of a 1:N protection switching device according to the present invention; as a NE, the device includes a connected fault detecting unit, a 1:N protection switching unit, and a communication unit; the functional entities may be connected in series or in two pairs. As long as it can interact normally to smoothly implement 1: N protection switching. Further, the communication unit is provided with a protection switching command format in which content expansion has been realized, so that operations such as encapsulation, analysis, and transmission of communication contents can be performed in a normal communication process.

In a specific application, when the NE is a remote node, the communication unit may receive a PSC message of a protection switching command (such as a signal fault) from the destination node, and send the received PSC message to the 1:N. The protection switching unit, the 1:N protection switching unit bridges the receiving end and the transmitting end of the working path corresponding to the PSC packet received on the node to which the node belongs to the protection path, and notifies the situation to the protection path. Communication unit. The communication unit sends a PSC message with the reverse request to the destination node according to the notification of the 1:N protection switching unit to notify the destination node of the specific protection switching situation.

It should be noted that the fault detecting unit can detect the working path shape on the side of the node to which it belongs. State, and notify the 1: N protection switching unit when a working path failure is detected. If the working path corresponding to the notification of the fault detecting unit is different from the working path corresponding to the PSC file from the destination node, the 1:N protection switching unit needs to compare the priorities of the two working paths. And the receiving end and the sending end traffic of the highest priority working path are bridged to the protection path on the node side to which the node belongs, and the foregoing method is used to notify the destination node through the communication unit.

In addition, when the NE is the destination node, the fault detecting unit can detect the working path state of the node to which it belongs, and notify the communication unit of the state in which the working path is detected, and the communication unit takes the situation in the form of a PSC message. Send to the remote node. Moreover, the communication unit can also receive the PSC message from the remote node and the command is a Reverse Request, and send the PSC message to the 1:N protection switching unit, and the 1:N protection switching unit will be on the side of the node to which it belongs. The receiving end and the sending end of the working path corresponding to the PSC packet 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 a PSC with the command No request to the remote node. The message is sent to notify the remote node that the protection switching has been completed.

In summary, the linear 1 : N protection technology of the packet transmission network of the present invention can smoothly implement the linear 1 : N protection of the packet transmission network, whether it is a method or a device embodied by a node or a system including a node.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included. Within the scope of protection of the present invention.

Claims

Claim

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.

2. The method according to claim 1, wherein the method further comprises: pre-expanding a request flag bit for indicating 1:N protection switching, and a protection switching command content indicating a specific working path.

3. The method according to claim 2, wherein the process of determining the working path for performing the 1:N protection switching comprises:

Alternatively, the remote node itself detects the working path failure, and compares the priority of the working path that the self-detected fault has been notified with the working path notified by the destination node, and then the receiving end of the working path with the highest priority on the own side and The sender traffic is bridged to the protection path.

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

5. The method of claim 4, wherein

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

6. A linear 1 : N protection device for a packet transmission network, characterized in that, in a packet transmission network, the device functions as a remote node, and includes a 1:N protection switching unit and a communication unit;

The device according to claim 6, further comprising a fault detecting unit, configured to detect a working path state of a node to which the node belongs, and notify the 1:N protection when a working path fault is detected. Switching unit

The device according to claim 6 or 7, wherein the communication unit 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. , the content is included in the 2-phase PSC protocol format;

A linear 1:N protection device for a packet transmission network, characterized in that, in a packet transmission network, the device serves as a destination node, including a fault detection unit, a 1:N protection switching unit, and a communication unit; The fault detecting unit is configured to detect a working path state of a node to which the node belongs, and notify the communication unit when a working path fault is detected;

The apparatus according to claim 9, wherein the communication unit 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, The content is included in the 2-phase PSC protocol format;

A linear 1 : N protection system for a packet transmission network, characterized in that the system comprises a remote node and a destination node in a packet transmission network;

The destination node is configured to notify the remote node to perform 1:N protection switching on the working path after detecting that the working path is faulty; and perform protection switching on the remote node according to the notification from the remote node. The working path is 1:N protection switching.

The system according to claim 11, wherein 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, the content including In the 2-phase PSC protocol format; The purpose of the _1: N protection switching request flag is: protection switching request ^ReVerSe request for '

Flag position

Indicate the content of the specific work path