JPH07118716B2 - Communication network failure recovery method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a next-generation broadband communication network (A
TM network: Asynchronous Transfer
The present invention relates to a communication network failure recovery method for maintaining high reliability in Mode Network).

[0002]

2. Description of the Related Art Conventional broadband networks (STM networks: Synch)
ronous Transfer Mode Network
In ork), a method called a self-healing ring for establishing a detour path and performing failure recovery control has been put into practical use in order to recover a failure at high speed.

The self-healing ring method is described in "TH Wu:" FibreNetwork S ".
service Survivability “Arte
chHouse, 1992 (by T. H. Wu:
"Fiber Network Service Survivability" Artec House, 1992) "(Reference 1)
Are classified and explained in.

Further, in the STM network, a method has been proposed in which a detour path called a self-healing network that can relatively quickly cope with multiple failures and is searched for by distributed processing to perform failure recovery control.

Regarding this self-healing network method, "Nishimura:" Autonomous distributed network failure recovery method-
NETRATS IEICE Technical Committee IN89-7
0, October 1989 "(reference 2) and" WD Gr.
over: “Performance Studies
of a Selfhealing Network
Protocol in Telecom Canad
a Long Haul Networks "IEEE
Globecom '90 by W. D. Glover: "Performance Studies of a Self-Healing Network Protocol in Telecom Canada Long Hall Networks" IEE Gloves Com, 1990
Year) ”(Reference 3).

In the next-generation broadband network (ATM network), the path connecting two nodes is generated asynchronously and is connected by the flow of an information aggregate (packet) of a predetermined length. , The path itself does not occupy a definite band in the physical link, but occupies a virtual band. In addition, in order to control the flow of packets, each communication node has a correspondence table of the destination to the path identifier added to the beginning of the received packet and the number to be added to the beginning of the packet at the time of transmission. Logically connected according to the correspondence table. Since the path identifier to be added to the packet is selected from the range of finite value, the upper limit of the number of usable path identifiers is set.

In the ATM network, a fast and flexible failure recovery means utilizing the above characteristics has not yet been sufficiently studied.

[0008]

In the ATM network, it is possible to directly apply the above-mentioned method of the STM network. However, in the self-healing ring, it is difficult to deal with multiple failures because the detour route is fixed. Further, the self-healing network has a problem that the processing time is longer than that of the ring method.

An object of the present invention is to provide a high speed and flexible failure recovery system utilizing the characteristics of the ATM network.

According to the present invention, in a broadband communication network in which information is transferred asynchronously in units of packets of a predetermined length, a path connects arbitrary two communication nodes with a virtual band, Each of the communication nodes evaluates the sum of the function of converting the path identifier in the header of the received packet, the function of sending to the desired physical link, and the virtual bandwidth of the path occupied by the physical link connecting the nodes. When a network having a function and having at least two routes that do not share a relay node and a relay link between the two nodes is configured, a normal route, the relay node and the relay are provided for one path. Information of one or more detour routes that do not share a link, that is, detour node number sequence information to be passed, is recorded in advance at both end nodes of the path, One of the both end nodes that has detected this failure at the time of the failure of the path conveys the detour test instruction by carrying it in the management information transmission packet according to the detour node number sequence information, while the node receiving the detour test instruction It is determined whether the sum of the virtual bandwidths of the physical links on the detour route exceeds the capacity of the physical link, whether the path identifier is available, and whether the physical link is a failure. , When the detour test command carrying the availability information is transferred and all the relay links can be detoured at the other end node of the path receiving the detour test command, the node at which the detour test command is issued Establishes connection relationship by path identifier,
When the information management information of the physical link held in the node is changed and all relay links are not detourable at the other end node of the path which receives the detour test command, according to the detour node number sequence information. In order to deal with the inability to continue the detour test, the extended detour node number sequence information indicating the extended detour path that supplements the detour node number sequence information is added to each node on the detour node number sequence or both end nodes of the path. In preparation for this, when the detour test command of a certain detour route is transmitted and the test of this detour route cannot be continued, the extended detour node number sequence information is used to detour the fault location and the detour test command and the detour confirmation command are exchanged. It is characterized by doing.

Further, according to the present invention, when performing a detour test on a detour route, when all the relay links cannot be detoured at the other end node of the path which has received the detour test command, the detour node number sequence information is used. In order to deal with the fact that it becomes impossible to continue the detour test, a route search means is used in which the node that cannot continue this test is the starting point and the node recorded after the detour node number sequence is the end point. It is characterized in that a detour route different from the detour node number sequence and the extended detour node number sequence is generated to avoid the detour impossibility factor.

By configuring the present invention in this way, the above object is achieved.

As the route searching means, for example, the route searching means described in Document 2 is used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 6. FIG. 1 is a network configuration diagram showing a first embodiment of a communication network failure recovery system of the present invention. A path 2 connecting nodes (hereinafter ND) 1 and 3 is provided.
An example in which one detour route 22 is defined for a path having the same end nodes (ND1, 3) as 1 is shown. 2 is a diagram for explaining transmission of information at the time of confirming a detour or not confirming a detour for forming a detour of the detour route in FIGS. 1 and 3. Further, FIG. 6 is a block diagram of a basic example of each communication node for processing a management information transmission packet.

In the present embodiment, the path test command 31 of one of the nodes at both ends of the path affected by the failure on the path of the path 21, for example, the path test instruction 31 of the path transmitted from the ND 1 in the management information transfer packet of the bypass path 22 is transmitted. It is transmitted to ND4, 5, and 6.

In each of the NDs 4, 5 and 6 of the relay nodes, as shown in FIG. 6, the management information transfer packet selected and received by the management information packet receiving section 61 is input to the management information packet processing / generating section 62 for management. Information packet processing /
The generation unit 62 determines whether or not the detour route 22 can be detoured based on the band management information from the band information management unit 63, and manages the permission information if the detour is possible and the non-permission information if it is not possible. Management information packet transmission unit 6 to be placed in information transmission packet
It sends from 4.

Then, when this management information transmission packet reaches the ND3 of the node at the other end, the management information packet processing / generating unit 62 in the ND3 puts the detour confirmation command 32 back on the management information transmission packet.

When this detour confirmation command 32 arrives at ND1 via ND6, 5, 4, detour to the detour route 22 is executed.

Further, when the disapproval information is recorded in the management information transmission packet, the node on the bypass route 22,
For example, the management information packet processing / generation unit 62 of the ND 6 generates the bypass nonconfirmation command 33, puts it on the management information transmission packet, and returns it to the ND 1 via the NDs 5 and 4.

Next, the operation of the second embodiment of the present invention will be described with reference to FIGS. 2, 3 and 6. FIG. 3 shows a second embodiment of the communication network failure recovery system of the present invention, and is a network configuration diagram in the case where two detour routes are set.
An example in which two detour routes 22 and 24 are set for a path having the same end nodes (ND1, 3) as 1 is shown. Each node in FIG. 3 has the configuration shown in FIG.

In this embodiment, both end nodes (ND1, 3) of the path affected by a failure on the path of the path 21
To each of the detour routes 2 and 24
The route test command 31 and the detour confirmation command 32 are exchanged in the management information transmission packets 2 and 24, and the detour confirmation command 32 is exchanged in the same procedure as in the first embodiment. Is used to perform the detour.

In this embodiment, two detour routes are set to double the detour route, but it goes without saying that the detour route may be triple or quadruple depending on the importance of the path. .

Next, a third embodiment of the present invention will be described with reference to FIGS. 1, 2 and 6 and FIG. FIG. 4 is a process flow chart in the third embodiment of the communication network failure recovery system of the present invention, which uses the extended bypass route 23 passing through the NDs 5, 7, and 6 shown in FIG. The processing after receiving 31 is shown. Further, each node in this embodiment has the configuration shown in FIG.

First, each node shown in FIG. 1, for example, ND5
Then, according to the route test command 31 along the detour route 22, the management information packet processing / generation unit 62 determines whether or not the detour is possible based on the capacity of the physical link used for the detour / the number of available path identifiers (step 41). ).

Next, at step 42, if it is judged that the detour along the detour route 22 is impossible, the extended detour route 2
It is determined whether or not the detour is possible based on the number of available physical link capacity / path identifiers from the extended detour node number sequence 26 indicating 3 to the extended detour node (ND5 → ND7 → ND6) (step 43).

When it is determined in step 44 that the extended bypass node does not exist, or when it is determined that the bypass to the ND 7 is impossible, the management information packet processing / generating unit 62 of the node that has made the determination is bypassed. The unconfirmed command 33 is generated, placed in the management information transmission packet, and returned (step 46).

When it is determined in step 44 that the detour to the extended detour node (ND7) is possible, or when it is determined in step 42 that the detour along the detour route 22 is possible, each node on the detour route 22 is subjected to the route test. The instruction 31 is transferred to the adjacent node (step 45).

Thereafter, the route test instruction 31 arrives at the node (ND3) at the other end of the path, and the same processing as in the first embodiment of the present invention is performed thereafter.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 1, 2 and 6 and FIG. FIG. 5 is a process flow chart in the fourth embodiment of the communication network failure recovery system of the present invention, which has a route search means and shows a process after receiving the route test instruction 31 in each node.
Further, each node in this embodiment has the configuration shown in FIG.

First, in the ND 5, for example, the management information packet processor / generator 62 uses the path test command 31 along the detour path 22 to determine whether or not detour is possible depending on the capacity of the physical link used for detour / the number of available path identifiers. A determination process is performed (step 51).

Next, at step 52, if it is determined that the detour along the detour route 22 is not possible, the management information packet processing / generating unit 62 determines from the extended detour node number sequence 26 indicating the extended detour route 23 that the extended detour node ( It is determined whether or not the detour is possible based on the capacity of the physical link to the ND 7) / the number of available path identifiers (step 53).

When it is determined in step 54 that the extended bypass node does not exist or the bypass to the ND7 is impossible, the route search means by the distributed processing, for example, pages 7 to 12 of the above-mentioned Document 2. In the broadcast phase and the return phase of the means described in (1), a node recorded after the detour node number sequence 25 is started from a node (for example, ND5) where the test cannot be continued based on the information of the detour node number sequence 25. (ND6)
Is executed as the end point.

After obtaining the search result by this route search means, the management information packet processing / generating unit 62 judges the search result (step 57). If this route search is successful, at step 52 and step 54, respectively. When it is determined to be possible, the route test instruction 31 is transferred to the adjacent node (step 55). After that, the detour to the extended detour route 23 is executed by the same process as the process described in the first embodiment.

When the route search fails in step 57, the management information packet processing / generating section 62 returns the detour nonconfirmation command 33 (step 58).

[0036]

As described above, the present invention has the following great effects.

That is, since the route to bypass is determined in advance, the bypass process at the time of a single failure is executed at high speed.

Further, the reliability can be further improved by multiplexing the detour path as necessary.

Further, even when a predetermined detour route cannot be used due to a double failure or the like, the extended detour route can be used for relief.

Furthermore, even if the detour route and the extended detour route cannot be repaired, it is possible to deal with them by the decentralized route searching means.

[Brief description of drawings]

FIG. 1 is a network configuration diagram showing a first embodiment of a communication network failure recovery system of the present invention.

FIG. 2 is a diagram for explaining transmission of information at the time of confirming a detour or not confirming a detour for forming a detour of a detour route in each embodiment of the present invention.

FIG. 3 is a network configuration diagram showing a second embodiment of the communication network failure recovery system of the present invention.

FIG. 4 is a processing flow chart in a third embodiment of the communication network failure recovery system of the present invention.

FIG. 5 is a processing flow chart in a fourth embodiment of the communication network failure recovery system of the present invention.

FIG. 6 is a block diagram of a basic example of each communication node for processing a management information transmission packet.

[Explanation of symbols]

 1, ..., 10 Communication node (ND) 11, ..., 18 Physical link 21 Path connecting nodes 1 and 3 22, 24 Detour route 23 Extended detour route 25 Detour node number sequence 26 Extended detour node number sequence 31 Route test Command 32 Detour confirmation command 33 Detour non-confirmation command 61 Management information packet reception unit 62 Management information packet processing / generation unit 63 Bandwidth information management unit 64 Management information packet transmission unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-235983 (JP, A) JP-A-6-37783 (JP, A) JP-A-4-257143 (JP, A) JP-A-4- 65942 (JP, A) IEICE Technical Report, Vol. 91 [270] (1991-10-17) Okanoue, Sakauchi, Hasegawa “Examination of integrated self-healing network” P. 31-36

Claims (2)

[Claims] 1. In a broadband communication network that transfers information in units of packets of a predetermined length that occur asynchronously, a path connects any two communication nodes with a virtual band, The communication node has a function of converting the path identifier of the header part of the received packet, a function of transmitting to a desired physical link, and a function of evaluating the sum of virtual bandwidths of paths occupied by physical links connecting the nodes. And a network capable of securing at least two routes that do not share the relay node and the relay link between the two nodes, the normal route and the relay node and the relay link are provided for one path. Information on the passing detour node number sequence, which is information on one or more detour routes that are not shared, is recorded in advance at both end nodes of the path, and One of the both end nodes that has detected this failure at the time of damage transmits the detour test command by carrying it in the management information transmission packet according to the detour node number sequence information, and the node receiving the detour test command transmits the detour test command to the detour route. For the upper physical link, it is determined whether the sum of virtual bands exceeds the capacity of the physical link, whether the path identifier is available, and whether the physical link is in trouble, and whether or not this is possible. When the detour test command carrying the information is transferred and all the relay links can be detoured at the other end node of the path which receives the detour test command, the path identifier is used in the node where the detour test command is issued. Before establishing the connection relationship, changing the information management information of the physical link held in the node, and receiving the detour test command An extension that supplements the detour node number sequence information in order to cope with the fact that the detour test according to the detour node number sequence information cannot be continued when all relay links are not detourable at the other end node of the path When each node on the detour node number sequence or both end nodes of the path is equipped with the extended detour node number sequence information indicating the detour route and the detour test command of a certain detour route is transmitted and the test of this detour route cannot be continued. A communication network failure recovery method characterized in that a failure location is detoured by the extended detour node number sequence information and the detour test command and the detour confirmation command are exchanged. 2. When performing a detour test on a detour route, when all relay links cannot be detoured at the other end node of the path that has received this detour test command, the detour test according to the detour node number sequence information is performed. In order to deal with the fact that continuation becomes impossible, the detour node number is used by using a route search means whose starting point is a node where continuation of this test is impossible and whose end point is a node recorded after the detour node number sequence. The communication network failure recovery method according to claim 1, wherein a detour route different from the column and the extended detour node number sequence is generated to avoid the detour impossibility factor.