JPH06232862A - Communication network fault recovering system - Google Patents

Abstract

PURPOSE:To shorten recovery time by reducing burden loaded on a node on a communication network for processing a message for searching a detour route. CONSTITUTION:Each node on the communication network is provided with a message sending table 110 for recording whether the present node or the connected link is corresponding to the propagation range of a message caused by a bus fault or not based on previous search processing, message sending judging means 120 for judging whether the present node or the connected link is corresponding to the propagation range of the message or not based on the record of the message sending table 110 when the message for searching the detour route caused by the bus fault is received, and message transmitting means 130 for executing message sending processing based on prescribed message sending conditions when the message sending judging means 120 judges it is corresponding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication network failure recovery system for searching for a detour route for the purpose of prompt recovery in the event of a failure such as a transmission line disconnection or transmission device failure in a communication network.

[0002]

2. Description of the Related Art With the increase in speed and capacity of communication networks, it has become more important to promptly deal with failures such as transmission line disconnection and transmission device failure.

However, it takes time to repair the faulty part. Therefore, usually, a method is used in which a detour route is secured by using the free capacity in the transmission path of the communication network, and the fault path is switched to the detour route to recover. A distributed control type detour route search method is considered as one method of this detour route search.

The following Documents 1 and 2 disclose the prior art of the distributed control type detour route search system.

Reference 1: Examination of fault recovery algorithm by distributed control (Technical Bulletin CS89-56 Komine, Nakajo, Miyazaki, Kokura,
Soejima; Fujitsu Laboratories Ltd.) Reference 2: Examination of switching VP presetting type ATM network self-healing method (Science Technical Report CS91-90 Kawamura, Sato; N
TT Transmission Systems Laboratories) First, before explaining the distributed control type detour route search method,
A transmission network as a communication network to which this search method is applied will be defined.

A plurality of transmission devices called nodes (or cross-connects) are distributed and arranged in the transmission network.
A transmission line called a link is appropriately connected between the nodes. The physical structure of the transmission network is as described above. In the transmission network, a path that bundles calls (channels) transmitted from one node to another node is set. This path is transmitted to the destination via some nodes. In each node, the path is input from the connection link, and the path is output to the link to be output according to the path route information in the node. In this way, connection is established in path units in each node, whereby a path is set between two regions (nodes), and calls (channels) generated between these regions can be connected through this path.

The decentralized control type detour route search method is used in the case where a failure such as a transmission line disconnection or a node failure occurs in such a transmission line, without going through a central control station which manages the entire transmission network. This is a method in which each node operates in an autonomous distributed manner to obtain a detour path. Both the faulty links and the path end points can be considered as the detour route sections, but here, it is considered to set up a detour route between the path end points.

For example, when a link failure (transmission path disconnection) occurs, one of the two nodes at both ends (termination points) of the failed path becomes a Sender node, and the other becomes a Chooser node. A message is sent from the Sender node to each link connected to the node. By repeating this operation, the message finally arrives at the Chooser node. In such an operation, if each node confirms that the free capacity of the output transmission line is equal to or greater than the faulty path capacity when sending a message, the Chooser node will set the free space in the transmission line from the route of the arrived message. It is possible to recognize the existence of a detour route using.

FIG. 2 shows an example of a conventional distributed control type detour route search method utilizing the techniques disclosed in the above-mentioned documents 1 and 2. In FIG. 2, a circle indicates a node, a thick solid line connecting the nodes indicates a link, and an arrow attached along each link indicates a message transmission direction. The transmission network shown in FIG. 2 is a system in which 16 nodes 1 to 16 are connected by links in a grid pattern, a path A is connected between the node 5 and the node 7, and the transmission route is the node 5 -> Node 6-
->Let's say node 7. Further, in order to facilitate understanding, it is assumed that each link connecting adjacent nodes has a free capacity equal to or larger than the capacity of the path A between the node 5 and the node 7. That is, any link can be used as a via link of the bypass route of the path A.

Now, when the link between the node 6 and the node 7 is broken, a link failure is detected by the failure detection mechanism of the network, and the node 5 at the terminal point of the path A that used the failed link. And the node 7 is notified that the path failure has occurred. Then, upon receiving the failure occurrence notification from the failure detection mechanism of the network, the node 5 and the node 7 at the termination point start the detour route search of the path A. From here, the operation of the distributed control type alternative route search method is performed.

First, the node 5 serves as a Sender node and the node 7 serves as a Chooser node, and the Sender node 5 sends a message to all connection links having a free capacity corresponding to the capacity of the failed path. Also, Chooser node 7 is Sen
Wait for the arrival of the message sent from the der node 5.
An example of the content of the message sent from the Sender node 5 is shown below.

[Example of Message Content] [1] Faulty path number: Logical number given to the corresponding path in the network in advance [2] Sender node / Chooser node number [3] Capacity of faulty path [4] Message Via node: Message is the history of the node [5] Number of via links (hop count): Updated from the number of links via the message at any time [6] Upper limit of the number of possible via links (hop limit): Link via which messages can be passed Upper limit of number The values of [1] to [3] and [6] in the above-mentioned message content are constant values determined according to the path connection, and the values do not change even when passing through a node. However, the values of [4] and [5] of the message content are added / updated every time when passing through the node.

For example, in the message content [4] in the message sent from the Sender node 5, "5" of the Sender node number is described as a transit node, and
In the message content [5], the initial value of the hop number is "0".
Is described. And in [6] of the message content,
For example, '6' is set as the predetermined hop limit value. The hop limit value of “6” means that the detour route must be configured with 6 links or less.

Next, the operation until the detour route is obtained by the message sent from the Sender node 5 will be described.

In the nodes 1, 6 and 9 which have received the message from the Sender node 5, first, the own node number is additionally described in the item of the transit node of [4] of the message content,
Increase the number of hops of [5] in the message content by 1 to 1
And Then, these nodes 1, 6, 9 further send a message to each link connected to the own node when the following message sending conditions are satisfied.

-Message sending condition- {1} The number of hops described in the message content [5] (the value after adding 1 at its own node) is less than the hop limit value.

{2} The node to which the local node will send a message is not already described in the message content [4].

{3} The free capacity of the link from which the local node sends a message is equal to or larger than the capacity of the failure path A.

{4} The own node is not a Chooser node (if the node is a Chooser node, no message is sent.

In the message sending process, when there are a plurality of links (that is, links connected to the own node) to send the message, the message is copied and sent. When receiving a message, each node in the network performs the same message sending process, and as a result, the message is propagated in all directions (this is called flooding).

The message basically propagates in the network until the number of hops reaches the hop limit. In this way, the message finally arrives at the Chooser node 7. In the Chooser node 7, the detour route candidate can be known from the transit node information described in [4] of the content of the arrived message.

FIG. 3 shows all detour route candidates obtained when the conventional distributed control type detour route search method is executed with a hop limit value of "6" in the transmission network shown in FIG. The Chooser node 7 selects an optimal alternative route from all the alternative route candidates. As an example of the selection method, it can be considered to select a route with the smallest number of hops. In the detour route candidates shown in FIG. 3, the minimum value of the hop number is 4, and the detour route candidates 1), 4), 6), and 9) correspond, and among these four detour route candidates, One will be selected.

[0023]

However, in the above-described conventional distributed control type detour route search method, since basically message propagation is performed until the hop limit is reached, there is a possibility that it will actually be adopted as a detour route. The total number of search routes (including the search routes for messages that do not reach the Chooser node) is very large compared to the high number of routes. For example, in the case of the transmission network shown in FIG.
The routes that are likely to be selected as the detour route are four routes with the number of hops being “4”, while the total number of search routes is 11 times that of 44 routes.

In other words, many of the detour route search messages transmitted by the conventional distributed control type detour route search method are invalid. In the transmission network shown in FIG. 2, when the total number of messages transmitted in the above-mentioned failure situation is calculated to be 97 messages, the number of messages involved in the search for the alternative route candidate with the hop number of 4 is 31 messages. Yes, about 1/3 of the total.

As described above, in the conventional distributed control type detour route search method, even an invalid message that is not involved in the selection of the detour route candidate that is actually adopted is sent, so that an extra load is applied to each node. There was a drawback.

The present invention has been made in view of the above circumstances, and when the detour route candidate is selected by sending a message for a detour route search when a failure occurs in the communication network, the number of messages to be sent can be suppressed to a small level. A detour route candidate can be quickly selected, and therefore, a load on a node on the communication network for processing a detour route search message can be reduced, and a recovery time can be shortened. The purpose is to provide a recovery method.

[0027]

According to the communication network failure recovery method of the present invention, when a path failure occurs, a detour route candidate is propagated by propagating a detour route search message between nodes on the communication network. There is a possibility that it will be adopted as a detour route when a path failure occurs by conducting a search for detour route candidates for each path between specific nodes such as between paths or links on a communication network in advance. One of the features is that pre-search processing for checking the range constituting the high detour route candidate for each path or connection link is completed.

Further, each node on the communication network is provided with a message sending table, a message sending judging means, and a message sending means.

Here, the message sending table is
Based on the preliminary search process, it is determined whether or not the own node or its connection link falls within a range forming a detour route candidate that is highly likely to be adopted as a detour route of the fault path when a path fault occurs. It was made possible.

Further, when the message transmission judging means receives a message for searching for a detour route caused by a path failure, it is within a range forming a detour route candidate which is likely to be adopted as a detour route of the failure path. It is determined based on the message transmission table whether or not the own node or its connection link is applicable.

Further, the message transmission means determines that the message transmission determination means is within a range in which the own node or its connection link constitutes a detour route candidate which is highly likely to be adopted as a detour route of the faulty path. At this time, a predetermined message sending process is executed.

With the above configuration, message propagation is realized by limiting the range of the detour route candidate that is highly likely to be adopted as the detour route of the fault path.
Repair the failure.

[0033]

In the communication network failure recovery method according to the present invention, during normal operation in which no path failure has occurred, pre-search processing utilizing the conventional distributed control type detour route search method or the like is performed in advance to perform path search. The range (node, link) that constitutes a detour route candidate that is highly likely to be adopted as a detour route when a failure occurs is checked for each path or connection link.

Then, based on the result of the preliminary search processing, each node on the communication network is provided with a highly probable detour route candidate in which the self node or its connecting link becomes a detour route when a path failure occurs. A message transmission table is set for each node or for each connection link of each node, which is capable of discriminating whether or not it corresponds to the range to be configured for each path that is a search target of the detour route candidate.

Then, when each node on the communication network receives the message for searching for the detour route generated by the path failure, first, within the range forming a detour route candidate having a high probability of becoming the detour route of the failure path. Whether or not the own node or its connection link is applicable is determined based on the message sending table, and only when it is applicable, the sending of the message for searching the detour route is executed.

Therefore, when a detour route candidate is selected by sending a detour route search message when a failure occurs on the communication network, the propagation range of the detour route search message on the communication network is actually adopted as the detour route. It is possible to quickly select a useful alternative route candidate while limiting the number of messages to be sent out to a limited range that is likely to be performed.

Therefore, by using the communication network failure recovery method according to the present invention, when a path failure actually occurs, the load on the node on the communication network for processing the message for searching the alternative route is reduced. It will be mitigated and recovery will be realized more quickly.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION A communication network failure recovery system according to the present invention selects a detour route candidate by propagating a detour route search message between nodes on a communication network when a path failure occurs. Hereinafter, a communication network failure recovery system according to an embodiment of the present invention will be described with reference to FIGS. 1 and 4 to 9.

FIG. 1 shows a functional configuration of a node (transmission device) arranged on a communication network. By equipping such a function, the communication network failure recovery system of one embodiment of the present invention is realized. To be done.

As shown in the figure, in this embodiment, the pre-search processing means 100 is installed in the node N arranged on the communication network.
A message sending table 110, a message sending judging means 120, and a message sending means 130.

Here, the pre-search processing means 100 is
Search for alternative route candidates for each path on the communication network in advance, and check the range (node, link) that constitutes the alternative route candidates that are likely to be adopted as alternative routes when a path failure occurs. The pre-search process is executed. The processing of the detour route search executed by the pre-search processing means 100 may use the conventional distributed control type detour route search method. Further, in this embodiment, the pre-search processing means 100 is provided for each node, but it may be provided for a centralized management station or the like that manages the entire communication network.

The message sending table 110 is based on the preliminary search processing of the preliminary search processing means 100.
Whether or not the own node or its connecting link falls within the range forming a detour route candidate that is highly likely to be adopted as a detour route of the fault path when a path fault occurs,
It is described so that it can be discriminated for each path to be searched for a detour route candidate. The table 110 may be set for each node, or for each connection link of the node. This message sending table 110
Are formed on the memory of each node N.

When the message transmission judging means 120 receives a message for searching for a detour route generated due to a path fault actually occurring on the communication network, it may be adopted as a detour route for the faulty path. Based on the message transmission table 110, it is determined whether or not the own node or its connection link falls within a range that constitutes a high detour route candidate. The table 11
If 0 is provided for each node, node determination is performed, and if provided for each link, determination is performed for each link.

The message sending means 130 determines that the node itself or a part of the connection link is within the range of constructing a detour route candidate which is highly likely to be adopted as a detour route of the faulty path.
When it is determined by, the predetermined message sending process is executed.

The above-mentioned pre-search processing means 100, message transmission determination means 120, and message transmission means 130 are
In this embodiment, a program or dedicated hardware (not necessarily a processor) that implements a predetermined operation by a processor mounted on each node is provided on a predetermined storage device of each node.

FIG. 4 shows the case of receiving a message for searching for a detour route sent by the occurrence of a path failure,
It shows a message sending process in each node.

First, when a message is received (step 200), the message transmission judging means 120 judges based on the message transmission table 110 "whether or not there is a high probability that the own node or its connection link will be a detour route". (Step 201).

When the probability is high, the message sending means 130 sends a predetermined message to the connection link of the own node or the corresponding connection link, and the process is terminated (step 202). However, in step 201
If it is determined that the probability is low (in the case of determining for each link, the link is low in probability), the process is terminated without sending the message.

In the above embodiment, the message for detour route search is propagated for the above-mentioned pre-search process even under the condition that no path failure actually occurs.
Therefore, the message for detour route search has the contents of the message such as the conventional distributed control type detour route search so that it can be determined whether it is for pre-search process or whether a path failure has actually occurred. It is slightly different from the method.

The communication network failure recovery system of one embodiment of the present invention will be described in detail below using a specific example of the communication network. In this example, the message sending table 110 is set not for each link,
It shall be held for each node.

FIG. 5 shows an example of a transmission network for recovering from a failure by performing a bypass route search when a path failure occurs by the communication network failure recovery method according to an embodiment of the present invention. In FIG. 5, the circles indicate the nodes shown in FIG. 1, the thick solid lines connecting the nodes indicate links, and the arrows attached to each link indicate the message transmission direction. The transmission network shown in FIG. 5 is also the same as the conventional one shown in FIG. 2, in which 16 nodes 1 to 16 are connected by links in a grid pattern, and a path is provided between the node 5 and the node 7. A
Are connected and the transmission path is node 5-> node 6-> node 7. In addition, to facilitate understanding, each link connecting adjacent nodes
It is assumed that both have free capacity equal to or larger than the path capacity between the node 5 and the node 7. In other words, any link can be used as a via link of the detour route.

Under normal operating conditions in which no fault has occurred in the path A, the preliminary search processing means 100 previously executes a preliminary search processing for searching for a bypass route for the path A. In the pre-search process performed by the pre-search processing means 100, first, the node 5 is changed to the Sender node,
Set node 7 as the Chooser node. And Sende
The r-node 5 sends a message to all connection links that have the same or more free space as the path A, and within the range of conditions such as the upper limit (hop limit) of the number of via links, the end point of the path A. All the alternative route candidates connecting the nodes 5 and 7 are searched.

Next, an example of the contents of the message transmitted for searching the alternative route in the embodiment of the present invention will be shown. It is almost the same as the message content used in the conventional distributed control type detour route search method, but it is possible to determine whether it is a message for pre-search processing or a message when an actual failure occurs. The points are very different.

-One Example of Message Contents for Searching Detour Route in One Embodiment of the Present Invention- [1] Message Identifier: The message for searching a detour route to be sent is for pre-search processing or when an actual failure occurs This is information for identifying whether or not the message is "preliminary" when the message is sent by the preliminary search processing unit 100, and "fault" is described in the message when the actual fault occurs.

[2] Path number: A logical number given to the corresponding path in the network in advance, and becomes a failure path number when a failure occurs. [3] Sender node / Chooser node number [4] Path capacity : Capacity of faulty path when a failure occurs [5] Message transit node: Message is a transit node history [6] Transit link number (hop count): Updates at any time by the number of transit message links [7] Transit link is possible Upper limit of number (hop limit): upper limit of the number of links through which a message can pass The values of [2] to [4] and [7] in the above message contents are the same as in the case of the conventional distributed control type detour route search method. In addition, it is a fixed value that is determined according to the path connection, and the value does not change even when passing through a node. However, the values of [5] and [6] of the message content are added / updated every time when passing through the node.

For example, in the message content [5] in the message sent from the Sender node 5, "5" of the Sender node number is described as a transit node, and
In the message content [6], the initial value of the hop number is "0".
Is described. And in [7] of the message content,
For example, '6' is set as the predetermined hop limit value. The hop limit value of “6” means that the detour route must be configured with 6 links or less.

Next, in the pre-search processing of the pre-search processing means 100, the operation until the detour route is obtained by the message sent from the Sender node 5 will be described.

In the nodes 1, 6 and 9 which have received the message from the Sender node 5, first, the own node number is additionally described in the item of the transit node of [5] of the message content,
Increase the number of hops of [6] in the message content by 1 to 1
And Then, these nodes 1, 6, 9 further send a message to each link connected to the own node when the following message sending conditions are satisfied.

-Message sending condition- {1} The number of hops described in the message content [6] (the value after adding 1 at the self node) is less than the hop limit value.

{2} The node to which the local node will send a message is not already described in the message content [5].

{3} The free capacity of the link from which the local node sends a message is equal to or larger than the capacity of the corresponding path A.

{4} The own node is not a Chooser node (if the node is a Chooser node, no message is sent.

In the message sending process, when there are a plurality of links (that is, links connected to the own node) to which the message should be sent, the message is copied and sent. When receiving a message, each node in the network performs the same message sending process, and as a result, the message is propagated in all directions (this is called flooding).

The message basically propagates in the network until the number of hops reaches the hop limit. In this way, the message finally arrives at the Chooser node 7. In the Chooser node 7, the detour route candidate can be known from the transit node information described in [5] of the arrived message content.

FIG. 6 shows all detour route candidates of the path A obtained when the pre-search process is executed with the hop limit value being “6” in the transmission network shown in FIG. At the time of an actual failure, the Chooser node 7 selects an optimal alternative route from all alternative route candidates detected from the received message. As an example of the selection method, it can be considered to select a route with the smallest number of hops. In the alternative route candidate shown in FIG. 6, the minimum value of the number of hops is 4,
The detour route candidates shown in 1), 3), 6), 7), 10), and 11) correspond, and one of these six detour route candidates is selected.

FIG. 7 shows six alternative route candidates having the minimum hop number of 4 extracted from all alternative route candidates notified to the Chooser node 7. Each of the detour route candidates extracted in FIG. 7 is highly likely to be adopted as a detour route when a failure occurs.

In the pre-search processing executed by the pre-search processing means 100, the range forming a detour route candidate (that is, the route shown in FIG. 7) that is highly likely to be adopted as a detour route when a failure occurs is It is detected as the spread range of the message for searching the alternative route for the path A. In the case of the path A in this example, the nodes 1, 2, 3, 5, 6, 7, 9, which are transit nodes in the alternative route candidates of FIG.
Nine nodes 10 and 11 and the links connecting these nodes are recognized as the spread range of the message.

It should be noted that similar detour route candidates are searched for paths between other nodes on the transmission network shown in FIG. 5, and the propagation range of the message is investigated for each path.

Then, in the message transmission table 110 provided in each node on the transmission network, based on the spread range of the message checked by the pre-search process, when the own node or its connecting link spreads the message when a failure occurs. Whether or not it corresponds to the range (that is, whether or not it corresponds to the range forming the detour route candidate that is likely to be adopted as the detour route of the faulty path) is determined for each path to be searched for the detour route candidate. It is recorded in a distinguishable manner. The message sending table may be equipped only for each node or may be installed for each connection link of the node. In the present embodiment, the case where only the node is equipped is shown.

FIG. 8 shows an example of the structure of the message transmission table 110 installed in all the nodes on the transmission network. On the left side of the message sending table 110, a path number column 111 in which identification numbers of all paths on the transmission network are arranged is provided, and on the right side of this path number column 111, a registration / non-registration entry column 112 is provided. It is composed. The registration / non-registration entry field 112 is the pass number field 111 on the left side.
By writing "1" or "0" for each path number described in, it is indicated whether or not the own node is within the propagation range of the message of the corresponding path.

The data "1" entered in the registration / non-registration entry field 112 means that the message is within the spillover range, and the data "0" means outside the message spillover range. For example, as a result of performing the pre-search process, the message transmission table 11 of the node which is the spread range of the message at the time of searching the detour route of the paths of the path numbers 2 and
As shown in FIG. 8, “0” has 0 entered in the registration / non-registration entry field 112 corresponding to the pass numbers 2 and 4. For a path detected by the pre-search process to be outside the message transmission range, '0' is entered in the registration / non-registration entry field 112 corresponding to the path number.

Next, a failure recovery process in one embodiment of the present invention when a link failure actually occurs between the nodes 6 and 7 of the path A will be described.

When the connection link between the nodes 6 and 7 is broken and causes a failure of the path A, a network failure detection mechanism (not shown) detects a link failure between the nodes 6 and 7. The occurrence of a path failure is notified to both termination point nodes 5 and 7 of the path A that used the failure link.

By the notification of the path failure from the failure detection mechanism of this network, the node 5 becomes the Sender node and the node 7 becomes
It becomes a Chooser node. Then, the Sender node 5 sends a detour route search message to all the connection links having a free capacity corresponding to the capacity of the failed path. Also, Cho
The oser node 7 waits for the arrival of the message sent from the Sender node 5. The content of the message sent from the Sender node 5 is the same as the message sent in the pre-search process, except for the message identifier. That is, in the message identifier [1] of the message content,
It is clearly indicated that the message is due to a failure.

Therefore, the other nodes 1, 6, 9 etc. receiving the message recognize that the message is a message at the time of failure occurrence by the identifier of [1] of the message content, and accordingly the receiving node receives the message. The sending determination means 120 is activated, and the message sending process shown in FIG. 4 is executed.

That is, it is confirmed by the message sending table 110 of the own node whether or not the own node corresponds to the node in the spread range of the received message. If the node does not correspond to a node in the spillover range of the message, the message is discarded and the message sending process ends. However, if the node corresponds to a node in the message spread range, the message sending unit 130 is activated and the message sending condition is the same as the message sending conditions {1} to {4} during the pre-search process. Whether the message can be sent or not is judged, and the message is sent or discarded.

The message transmission process shown in FIG. 4 is repeated at the nodes set as the message transmission range on the message transmission table 110 of each node, so that the message is propagated from the Sender node 5 to the Chooser node 7. Is realized, the detour route candidate is detected by the message arriving at Chooser node 7,
Fault recovery is achieved by one detour route selected from the detected detour route candidates.

In the method of one embodiment as described above, the process of transmitting the message for searching the alternative route when a failure occurs is executed only to the nodes in the range that is highly likely to be adopted as the alternative route. It is possible to promptly select a useful alternative route route while suppressing the number of sent messages, and when a path failure actually occurs, a message on the communication network for processing the alternate route search message is processed. The load on the node will be reduced and recovery will be realized more quickly.

FIG. 9 shows the number of processing messages in each node on the transmission network when a failure occurs, comparing the case where the conventional distributed control type alternative route search method is used and the case where one embodiment is used. It is a thing. In addition, in FIG.
The node in which a bar line "-" is entered instead of a numerical value is a node which is set outside the message propagation range by the pre-search process and does not perform the message sending process.

As shown in FIG. 9, the number of messages to be processed is 97 in the conventional method, whereas it is 27 in one embodiment. Further, in the case of the conventional method, all the 16 nodes on the network perform the message transmission processing, but in one embodiment, only 9 nodes are required. Thus, according to one embodiment, it is possible to significantly reduce the number of message transmissions and the number of nodes that perform message transmission processing. Then, such actions and effects become more effective as the scale of the network increases and the hop limit increases.

In the above embodiment, the case where the detour route search is performed between the nodes which are the termination points of the faulty path has been shown. However, the bypass route of each path is searched for between the nodes at both ends of the connection link that is causing a failure such as a transmission line disconnection, and in the above-mentioned message sending table 110, the connection of each connection link on the communication network to its own node May be described so that it can be discriminated whether or not is a message transmission range.

Further, in the embodiment, the message sending permission / inhibition decision is made for each node, that is, the message sending table for the node is provided. However, the table is provided for each link and the message sending table is provided for each link. It may be possible to judge whether or not the message can be transmitted.

[0083]

According to the communication network failure recovery method of the present invention,
During normal operation with no path failure, it is highly likely that it will be adopted as a bypass route when a path failure occurs by performing a prior search process using the conventional distributed control type alternative route search method in advance. The range forming the detour route candidate is checked for each path or connection link.

Then, based on the result of the preliminary search processing, each node on the communication network is provided with a highly probable detour route candidate in which its own node or its connecting link becomes a detour route when a path failure occurs. A message sending table is set for each node or for each link so that it can be discriminated whether or not it falls within the range to be configured for each path or connection link that is a search target for a detour route candidate.

When each node on the communication network receives the message for searching the detour route caused by the path failure, first, within the range forming the detour route candidate having a high probability of becoming the detour route of the failure path. Based on the message sending table, it is judged whether or not the own node or its connection link is applicable, and only when it is applicable, the connection link of the node or the sending of the message for detour route search to the applicable link To execute.

Therefore, when a detour route candidate is selected by sending a detour route search message when a failure occurs on the communication network, the propagation range of the detour route search message on the communication network is actually adopted as the detour route. It is possible to quickly select a useful alternative route candidate while limiting the number of messages to be sent out to a limited range that is likely to be performed.

Therefore, by using the communication network failure recovery method according to the present invention, when a path failure actually occurs, the load on the node on the communication network for processing the message for searching the alternative route is reduced. It will be mitigated and recovery will be realized more quickly.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of a node that realizes an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional distributed control type detour route search method.

FIG. 3 is an explanatory diagram of alternative route candidates obtained by a conventional distributed control type alternative route search method.

FIG. 4 is an explanatory diagram of a message sending process when a path failure occurs according to the embodiment of this invention.

FIG. 5 is an explanatory diagram of a transmission network using a distributed control type alternative route search system according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of detour route candidates obtained by a preliminary search process according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of detour route candidates that are highly likely to be detour routes obtained by a preliminary search process according to an embodiment of the present invention.

FIG. 8 is a configuration diagram of a message sending table used in an embodiment of the present invention.

FIG. 9 is an explanatory diagram of actions and effects according to an embodiment of the present invention.

[Explanation of symbols]

 N node 100 Preliminary search processing means 110 Message transmission table 111 Path number column 112 Registration / non-registration entry column 120 Message transmission determination means 130 Message transmission means

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Claims (1)

[Claims] 1. A communication network failure recovery method for selecting a detour route candidate by propagating a message for searching a detour route between nodes on a communication network when a path failure occurs. A range that constitutes a detour route candidate that is likely to be adopted as a detour route when a path failure occurs by conducting a search for detour route candidates for each path between specific nodes such as between paths or links above Is completed for each path or connection link, and each node on the communication network is connected to its own node or its own node when a path failure occurs, based on the above-mentioned preliminary search process. A message sending table that can determine whether or not a link corresponds to a node or a link that constitutes a detour route candidate that is likely to be adopted as a detour route of the fault path , When receiving a message for searching a detour route caused by a path failure, the self-node and the self-node are connected to the range that constitutes the detour route candidate that is likely to be adopted as the detour route of the faulty path. A message transmission judging means for judging whether or not a link corresponds based on the message transmission table, and a detour having a high possibility that the own node or a link connected to the own node is adopted as a detour route of the faulty path. When the message transmission determination means determines that the route constitutes a route candidate, the message transmission means performs a predetermined message transmission process, and the detour having a high possibility of being adopted as a detour route of the fault path. Propagation of the message is limited to the range that constitutes the route candidate, and communication is performed to recover from the failure. Network disaster recovery system.