JPH07162422A - Self-healing method for communication network - Google Patents

Abstract

PURPOSE:To reduce the quantity of a network resource required for the restoration by eliminating a duplicate path appearing between duplicate node paths when a path passes through the same node in a tentative bypass and setting the bypass again. CONSTITUTION:A node 2 receiving a search message SM allocates a fault path stored in a control section 20 on the occurrence of a fault to bypass information represented in the SM to generate a bypass and to return an acknowledge message IM. The control section 20 of the node 2 in this case conducts the following operation. After the reception of the SM, a path satisfying an idle capacity of the bypass with respect to the faulty path is selected to generate a tentative path. Let (n) be a first node of the selected path and (m) be a 2nd node, and when a node satisfying n=m is in existence, the path inbetween is eliminated and its node number is stored. The operation above is repeated till the (n) is a final node of the tentative path. In order to decide finally the bypass, switching node information and bypass information are accommodated in the acknowledge message IN and the message is sent to nodes 2-4 on the bypass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for communication performed using a network. In particular, it relates to transmission line failure recovery technology. What is "self-healing" (autonomous distributed failure recovery)?
When a failure occurs, a plurality of related nodes exchange control information with each other and restore the communication without a command from the host controller.

[0002]

2. Description of the Related Art In order to quickly set up a bypass path when a failure occurs in a communication network, a centralized control node that centrally manages the communication network is not used, but between each node in the communication network. A self-healing method has been studied in which a detour path route is autonomously distributed and searched and set only by sending and receiving a recovery message. Here, the centralized control node is
It means a node that manages the entire communication network in a unified manner. When a communication network failure occurs, an optimal detour path route is calculated and a path switching instruction is given to each node.

A conventional example will be described with reference to FIGS. 9 to 14. 9 to 12 are views for explaining the conventional self-healing method. 13 and 14 are diagrams showing redundant detour path routes. The solid line in the figure indicates the working path route accommodated in the faulty transmission line, and the alternate long and short dash line indicates the detour path route. When a failure occurs in the transmission line 6, the nodes 1 and 2 at both ends of the failure transmission line receive the alarm information, and the node 1
Or one of the two is Sender and the other is Choose
It becomes r, and failure recovery is performed by the following phases. Here, Sender is a node on the side that generates and sends a search message SM including failure information, and Chooser is a confirmation message IM for receiving the search message SM and setting a bypass path route based on this. Is a node on the side of sending back. In the following, node 1 will be the Sender and node 2 will be
Let be Chooser. The procedure for defining each of the Sender and Chooser is not directly related to the present invention, so a detailed description thereof will be omitted.
The node serving as the er and the node serving as the Chooser may be fixedly determined in advance, or the alarm information may include information as to which serves as the Sender and which serves as the Chooser.

Each of the nodes 1 to 4 is mainly composed of an XC section 21 having a path cross-connect function and a control section (executing a self-healing process) 20 having a control function of its own node. Hereinafter, the self-healing process will be described separately for the activation phase, the search phase, and the confirmation phase. In the start-up phase, as shown in FIG. 9, the node 1 which is the sender triggers the reception of the alarm information to trigger the search message SM including the information necessary for the search of the bypass path to the adjacent nodes 3 and others. Broadcast. The search phase is, as shown in FIG. 10, a search message SM.
The adjacent node 3 that has received the message secures a free path, adds its own node ID and free space information to the search message SM, and broadcasts the search message SM to the adjacent nodes 4 and others. Similarly, Node 4 is Choose
The search message SM is also notified to the node 2 which is r.
In the confirmation phase, as shown in FIG. 11, when the node 2, which is the Chooser, receives the search message SM and obtains the detour path route, the nodes 4, 3 on the detour path route,
1 returns a confirmation message IM to node 1 and receives the confirmation message IM.
Finalizes the bypass path route by connecting the terminals for the bypass path route. FIG. 12 shows the detour path route after the final setting.

[0005]

In the self-healing method shown in the conventional example, when the bypass path route is finally set at the node 2 which is the Chooser, the bypass path route is finally set without considering the failure path route. , As it was switched as it is, as shown by the shaded portion in FIG. 13 or FIG.
“Fold” or “loop” in the detour path route after final setting
As a result, there is a problem that a redundant section is generated, and as a result, the recovery rate is lowered and the network resources required for the recovery are increased.
In other words, the path route used for the search message to reach the Chooser from the Sender will be set as the detour path route without any further consideration, so avoid it even if a redundant section occurs. I can't.

[0006] The present invention has been made against such a background, and when a failure occurs, a detour path route having no redundant section can be set to reduce the network resources required for restoration. The purpose is to provide a self-healing method.

[0007]

According to the present invention, a first step of detecting a failure in a transmission line connected to a self-node and one or more nodes communicating with the self-node are provided. Of the communication network including a second step of notifying the failure of the above, and a third step of setting a detour path route using a normal transmission path connecting between the node notified of this failure and the own node. It is a self-healing method.

Here, the feature of the present invention is that the once set detour path route is set as a temporary detour path route, and whether or not the same node overlaps in this temporary detour path route is determined. A fourth step of judging, and a fifth step of resetting the detour path route by deleting the overlapping part appearing between the overlapping nodes when the same node is judged to overlap by the fourth step. Where it is.

It is desirable to repeat the first to fifth steps until all the paths in the communication network are restored or there are no detour path routes that can be set.

[0010]

When the Chooser sets the detour path route, the detour path route is provisionally created by adding the detour path route searched by the search message and the fault path route information stored in advance. Then, it is determined whether or not the same node is included in the temporary detour path route, and when the same node is included, the detour path route between the nodes is deleted and the detour path route is created again. To do.
That is, if the same node is redundantly included in the temporary detour path route, it means that there is a redundant detour path route such as the above-mentioned “turnback” or “loop”. Therefore, by creating a detour path route that deletes this, it is possible to finally set up a detour path route that does not include a redundant detour path route.

As a result, it is possible to effectively use the network resources in the sections that were conventionally wasted, and it is possible to obtain a high recovery rate with less network resources. According to the method of the present invention, each node stores the path route information accommodated in its own node, and the confirmation message used in the conventional self-healing method includes the switching node information, the detour path route information after restoration, and the failed path. Since it can be realized by adding route information, it can be realized without impairing the advantages of the conventional self-healing method such as high speed and localization of switching range.

Here, the tentative detour path route can be defined, for example, as the tentative path route that the search message has passed through before reaching the Chooser. That is, the detour path route is finally set by the return of the confirmation message from the Chooser, but some path route exists before the search message reaches the Chooser. A temporary detour path route is created by adding this path route and the path route before the failure excluding the failure section. In the conventional example, this is finally set as the final detour path route without determining whether or not there is a redundant section, which causes a problem of a redundant section.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining the method of the embodiment of the present invention. In FIG. 1, the transmission line 16 connected to the nodes 1 and 2
It is assumed that a failure has occurred. Here, node 1 is the Sender and node 2 is the Chooser.

According to the present invention, a transmission line 1 connected to a node 1
The first step of detecting that there is a failure in 6 and the transmission line 16 in nodes 3, 4 and 2 communicating with node 1.
The second step of notifying the failure of 1 and the normal transmission paths 10, 11, 13 and 14 connecting the nodes 3, 4, 2 and node 1 notified of this failure are used to set the detour path path. The self-healing method for a communication network including the third step of

Here, the feature of the present invention is that the once set detour path route is a temporary detour path route, and whether the same node overlaps in this temporary detour path route or not. A fourth step of judging, and a fifth step of resetting the detour path route by deleting the overlapping part appearing between the overlapping nodes when the same node is judged to overlap by the fourth step. Where it is. The first to fifth steps are repeated until all the paths in the communication network are restored or until there are no settable detour path routes. These procedures are for each node 1
4 to 4 are programmed in the control unit 20. Further, the control unit 20 is provided with a database that stores path route information within the communication network.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. 2 to 4 are views for explaining the method of the embodiment of the present invention following FIG. FIG. 5 is a conceptual diagram for creating a bypass path route of the Chooser in the embodiment of the present invention. FIG. 6 is a flowchart showing the operation of the control unit 20. FIG. 7 is a diagram showing a detour path route setting situation before sending a confirmation message. FIG. 8 is a diagram for explaining the operation of each node on the detour path route. Hereinafter, the self-healing process will be described separately for the activation phase, the search phase, and the confirmation phase.

In the start-up phase, as shown in FIG. 1, when a failure occurs in the transmission line 16, the node 1 which is the failure end node receiving the alarm information sends the search message SM containing the information necessary for the recovery to the adjacent node. Broadcast to node 3 and others. This operation is similar to the operation already described in the conventional example. Also, at this time, the node 1 that is the Sender
And Node 2, which is the Chooser, stores the failure path route information. In the search phase, as shown in FIG. 2, the node 3 that has received the search message SM secures an empty path and adds its own node ID, empty path (detour path) information, and empty path capacity information to the search message SM. Broadcast to node 4 and other nodes that are adjacent nodes. Similarly, node 4 is Ch
The search message SM is also notified to the node 2 which is the ooser. This operation is similar to the operation already described in the conventional example. In the confirmation phase, as shown in FIG. 3, the node 2 that has received the search message SM allocates the failure path route information stored at the time of failure to the bypass path route information shown in the search message SM to create a bypass path route. Then, the confirmation message IM is returned, but at this time, the node 2 which is the Chooser performs the following processing.

1. After receiving the search message SM, a path satisfying the free capacity of the bypass path is selected from the failure paths. 5A and 5B, the path route excluding the failure section among the failure path routes shown by the solid line in FIG. 5A and the path route in which the search message arrives shown in FIG.
2. Create the temporary detour path route shown in (C). 3. Determine whether the same node does not appear multiple times in the temporary detour path route. When the same node appears multiple times in the temporary detour path route, the path route between the same nodes is deleted as shown in FIG. 5D, and the detour path route is finally set. In addition, at this time, the node that needs to newly switch the path route is recognized. The confirmation message IM including the new switching node information, the bypass path route information, and the failed path route information is sent out on the bypass path route. In this way, the detour path route shown in FIG. 4 is finally set. Table 1 shows the format of the confirmation message IM.

[0019]

[Table 1] The operation of the controller 20 of the node 2 which is the chooser will be described in more detail with reference to FIG. Search message SM is Ch
When it arrives at node 2 which is an ooser (S1), a path satisfying the free capacity of the detour is selected from the failed paths (S2). A provisional path route is created (S3). It is determined whether or not there is a node with n = m, where n is the first node of the provisional path route and m is the second node (S
5). If there is a node with n = m, the path route between the nth node and the mth node is deleted and the node number is stored (S8). This is repeated until n becomes the last node of the provisional path route (S6 → S10). Since the remaining nodes become the nodes 2, 3, and 4 on the bypass path route, the confirmation message IM contains the switch node information and the bypass path route information to finalize the bypass path route, and the nodes on the bypass path route are stored. Send to 2, 3 and 4 (S1
1).

On the other hand, the nodes 2, 3 and 4 which have received the confirmation message IM check the contents of the confirmation message IM, and after performing the following processing, send the confirmation message IM to the nodes on the bypass path route. It is sent to 2, 3, and 4, respectively. FIG. 8 shows a provisional alternative path route setting status before sending the confirmation message IM. When the own node ID is not shown in the switching node information in the confirmation message IM, this node is not a node that newly switches. At this time, the following processing is performed. A) When the self-node ID is indicated in the detour path route information, the terminals secured for the detour path route are connected when the search message SM is received. The connection status at this time is shown in FIG.
b) When the self-node ID is not included in the detour path route information, the self-node hits a redundant section such as a loopback or a loop, so that the reserved capacity and the terminal for the detour path are released. The connection status at this time is shown in FIG.
Own node ID in the switching node information in the confirmation message IM
Is indicated, this node is a node that newly switches. This node is based on the detour path route information,
The terminal for the detour path route and the terminal used by the failed path route are connected. Also, the reserved capacity in the redundant section and the terminal for the bypass path are released. The connection status at this time is shown in FIG. It should be noted that, in order to recognize that the confirmation message IM is correct, the Choose Path is selected by the failed path route information and the detour path route information in the confirmation message IM.
It is also possible to confirm that there is no error in the message content by re-performing the operation of deleting the redundant section performed by r for each node and reconfirming that the own node is the node that actually switches. it can. The above operation is repeated until all paths are restored or there are no bypass paths that can be set in the network.

[0021]

As described above, according to the present invention,
By eliminating redundant sections on the alternate path route such as “turnback” or “loop” when setting up the alternate path route, network resources required for recovery can be reduced compared to the conventional self-healing method, and a more economical network can be created. Can be configured.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a method according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a method according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining a method according to an embodiment of the present invention.

FIG. 5 is a conceptual diagram of creating a bypass path route of a Chooser in the embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the control unit.

FIG. 7 is a diagram showing a provisional alternative path route setting status before sending a confirmation message.

FIG. 8 is a diagram for explaining the operation of each node on the detour path route.

FIG. 9 is a diagram for explaining a conventional self-healing method.

FIG. 10 is a diagram for explaining a conventional self-healing method.

FIG. 11 is a diagram for explaining a conventional self-healing method.

FIG. 12 is a diagram for explaining a conventional self-healing method.

FIG. 13 is a diagram showing redundant detour path routes.

FIG. 14 is a diagram showing redundant detour path routes.

[Explanation of symbols]

 1 to 5 nodes 10 to 18 transmission line 20 control unit 21 XC unit IM confirmation message SM search message

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H04L 29/14 9371-5K H04L 13/00 311 (72) Inventor Takao Kawada Hajime Uchiyuki, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corp. 1-6

Claims (2)

[Claims] 1. A first step of detecting that a transmission line connected to the own node has a failure, and a second step of notifying one or more nodes communicating with the own node of the failure of this transmission line. In a self-healing method for a communication network, which comprises a step and a third step of setting a detour path route using a normal transmission line connecting between the node notified of this failure and its own node, The detour path route is set as a tentative detour path route, and a fourth step of determining whether or not the same node overlaps in this tentative detour path route, and the same node is duplicated by this fourth step And a fifth step of resetting the detour path route by deleting the overlapping portion appearing between the overlapping nodes when it is determined that the self-healing method of the communication network. 2. The self-healing method for a communication network according to claim 1, wherein the first to fifth steps are repeated until all paths in the communication network are restored or there is no detour path route that can be set.