JP2003244202A - Path switching system and method, and communication equipment and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable network by shortening a service unavailable time even when the network breaks down at a plurality of places. <P>SOLUTION: In a network where at least three paths exist between an input device 1 and an output device 2 with certain traffic, a current path 31 and a plurality of preliminary paths 32-38 are previously set as paths through which the traffic passes between the input device 1 and the output device 2 (by a path setting part 1b), and numbers for identifying respective circuits 3a-3h in the network are previously assigned to those circuits, and the group of the numbers of the lines whose communication is not affected even by failure is registered and managed as a path management table 21 for those respective paths 31-38 (by a path management table registering part 1d), and when any failure is occurred in any line (by a line failure occurrence detecting part 1c), whether or not path switching should be executed is determined by referring to the path management table 21 (by a path switching necessity determination part 1e), and when it is necessary, the conductable path is selected by referring to the path management table 21, and the path switching is executed (by a path switching part 1f). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a path switching control technique when a failure occurs in a network such as a packet transfer network, and more particularly, for example, MPLS (Multi Protocol Lab).
The present invention relates to a path switching technology suitable for shortening service interruption time by applying it to a failure bypass technology of el Switching).

[0002]

2. Description of the Related Art In consideration of compatibility with IP (Internet Protocol), which has become mainstream in the Internet in recent years,
As a technique for increasing the speed and capacity of data transfer, for example, IETF (Internet Engineering Task Force)
The technology such as MPLS, which is being standardized by, is drawing attention.

In this MPLS, a short fixed length identification mark called a "label" is used instead of the technique of transferring to the router by using the IP header. MPLS like this
Routers (Label Switching Router: LSR)
In the network configured by, each router holds the path information indicating to which router the packet is to be transferred next according to the destination of the packet, and the transfer route (path) of each packet is identified by the label.

For example, when a packet arrives at a router (edge router) at the entrance of this network, a label is added to the route information in the packet and the packet is transferred to the next router. The next router refers to the stored path information based on the label attached to the received packet, determines which router the packet should be transferred to, and sends the packet to an appropriate transfer destination.

Then, the edge router at the exit to the external network removes the label from the arrived packet and transfers it to the outside router. By thus transferring the packet based on the label, the transfer processing and the route calculation processing can be separated, the load on each router is reduced, and the processing speed is increased.

Further, in this MPLS, since functions such as bandwidth guarantee and high-speed failure bypass can be implemented together, it is possible to provide a highly reliable leased line service with a short service interruption time at the time of failure.

In the conventional fault detouring technology using MPLS,
In order to deal with the case where a failure occurs in the path set between the traffic input side device and the traffic output side device, a backup path is preset in addition to the working path, and path switching in the event of a failure ( Path protection) can be performed at high speed.

FIG. 6 is a block diagram showing a configuration example of a conventional MPLS network, and FIG. 7 is a block diagram showing a path switching operation example in the network in FIG.

In the network having the configuration shown in FIG.
There are a plurality of routes from the traffic input device 61 to the traffic output device 62. For example, as shown in FIG.
There are two paths (path 7) used for transfer in the network.
1. Pass 72) Set.

Of these, the path 71 is set as a normally used path (working path), and a failure 73 is set on this working path 71.
If the error occurs, the device that detects it (the relay device 6
3b) notifies the input device 61 of the occurrence of a failure (failure notification 74), and the notified input device 61 changes the identifier of the path in the label from the working path 71 to the backup path 72. Path switching (75) to the path 72 (preliminary path), that is, path protection is executed.

With such a path protection technique, the input device 61 to the output device 62 by the backup path 72 are not required to wait for the recovery of the failure occurrence factor on the working path 71.
You can restore your traffic.

However, in such a conventional path switching (path protection) technique, even in a network having three or more routes from the input device 61 to the output device 62, there are two preset paths. (Working path 71, backup path 72), and if a failure occurs on both paths, the service is cut off until the cause of failure on either path is restored, and high reliability as a network is achieved. Sex cannot be secured.

A study of reducing the probability of such a service interruption by avoiding the duplication of the route of the working path and the protection path on the network as much as possible is described in Matsuoka et al.
Annual Conference of the Society of Shinkai B-6-21 ”.

[0014]

The problem to be solved by the prior art is that in the prior art, if a failure occurs on this backup path after switching to the backup path due to a failure on the working path, the service will be interrupted. This is a point that cannot be avoided.

An object of the present invention is to solve these problems of the prior art and to further improve the reliability of the network.

[0016]

In order to achieve the above object, according to the present invention, in a network in which three or more routes exist between an input device and an output device of a certain traffic, the input device and the output device are In between, a working path and a plurality of protection paths are set in advance as paths through which the traffic passes, and a number (line identification number) for identifying the line in advance is assigned to each line in the network, causing a failure. Also registers and manages a set of line numbers (line identification numbers) that do not affect communication on the relevant path as a path management table for each path, and if a failure occurs in the network, the device that detects it Notifies the input device of the line identification number corresponding to the failure point, and the input device refers to the path management table based on the notification to judge whether switching is necessary,
If necessary, the path management table is referenced to select a path that can be conducted, and the path is switched to.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a network provided with a path switching system according to the present invention, and FIG. 2 is a configuration example of a path management table registered by the path management table registration section in FIG. Explanatory drawing shown in FIG.
1 is an explanatory diagram showing a path setting example in the network of FIG. 1, FIG. 4 is an explanatory diagram showing a path switching processing example in the network of FIG. 1, and FIG. 5 is a processing operation example of the path switching system in FIG. It is a flowchart.

In the network shown in FIG. 1, the relay devices 3a to 3 are provided between the traffic input device 1 and the traffic output device 2.
d is provided, there are three or more routes, and a path is set on the routes to pass traffic. Input device 1 and output device 2, and relay device 3a
Identification numbers are assigned to the lines 4a to 4h between 3d to 3d.

Hereinafter, it is assumed that the network of this example performs packet transfer based on the label by MPLS described in the above-mentioned prior art, but the present invention is not limited to this.

The input device 1 is a CPU (Central Processi).
ng Unit), a main memory, a display device, an input device, and an external storage device, and performs computer processing operations. For example, a CD-ROM via an optical disk drive device or the like.
After installing a program or data recorded in a storage medium such as an external storage device into the external storage device, the main memory is read from this external storage device and processed by the CPU to perform path switching control according to the present invention. Each processing unit for configuring.

That is, the input device 1 includes the path setting unit 1
b, failure occurrence detection unit 1c, path management table registration unit 1
A path control unit 1a including a path switching necessity determination unit 1e, a path switching unit 1f, and a path switching unit 1f is provided. The path setting unit 1b sets a current path and a plurality of (two or more) spare paths.

In the path management table registration section 1d,
For each path, the identification number of each of the lines 4a to 4h that is not on the path and has no effect on communication on the path even if a failure occurs
The information associated with is registered as the path management table 21 having the configuration shown in FIG.

The failure occurrence detecting section 1c detects the occurrence of failures in the lines 4g and 4h in its own device (input device 1), and
The detection is performed based on the reception of the failure occurrence notification of the lines 4a to 4f from another device, and the occurrence of the failure of each of the lines 4a to 4h is detected.

Further, in the path switching necessity judgment unit 1e, when the failure occurrence detection unit 1c detects the occurrence of a line failure, the information of the path management table 21 registered by the path management table registration unit 1 is referred to and the failure occurrence line If the identification number is not registered in association with the currently selected path, it is determined that switching to another path is necessary.

Then, in response to the judgment by the path switching necessity judgment unit 1e that the path switching is necessary, the path switching unit 1f refers to the registration information of the path management table 21, and the identification number of the failure occurrence circuit corresponds. Select the attached path and switch the path.

This path switching is performed by changing the label of the packet so that the packet sent from the input device 1 reaches the output device 2 via the selected path.

In this example shown in FIG. 3, there are eight routes (physical lines) between the input device 1 and the output device 2, and for each route, one of FIGS. As shown in h), the paths 31 to 38 are set.

Of these, the path 31 is the working path and the other paths 32 to 38 are backup paths. As shown in FIG. 2, in the path management table 21, each path 31 to 38 is a path type. Is registered as each path 31 to 3
Corresponding to No. 8, the identification numbers of each of the lines 4a to 4h which are not on the path are registered as the bypass unnecessary fault location.

For example, with respect to the working path 31, ~ is registered in association with each other as a bypass unnecessary failure point,
The lines 4b, 4 to which these identification numbers are assigned
Even if a failure occurs in c, 4e, 4f, 4h, the working path 3
No path switching from 1 to another path occurs.

In the network having such a configuration,
As shown in FIG. 4, a path protection operation will be described in the case where a failure 41 occurs in the line 4e (identification number) and then a failure 42 occurs in the line 4a (identification number).

In the network shown in FIG. 4, as shown in FIG. 1, each line 4a to 4h is given a line identification number (to), and as shown in FIG. , 7 spare paths 32 to 38 are set, and as shown in FIG. 2, a set of line identification numbers (to) of the respective lines 4a to 4h having no influence on communication even if a failure occurs is set for each path. It is managed as the path management table 21.

Here, in the network shown in FIG.
The fault 41 has already occurred in the line 4e having the line identification number. However, since the line identification number of the line 4e is registered for the working path 31 in the path management table 21, path switching is unnecessary.

When a new failure 42 occurs in the line 4a having the line identification number on the working path 31 in the state where the failure 41 occurs in the line 4e, the device (relay device 3b) that has detected it. ) Notifies the input device 1 of the location of the failure using the line identifier () (failure notification 43). Note that this notification may be performed via the relay device 3a or directly via another communication means.

In the input device 1, when the failure occurrence detecting section 1c receives this notification and detects the occurrence of a failure in the line, first, the path switching necessity determining section 1e follows the sequence shown in FIG.
By referring to the path management table 21 shown in FIG.
It is determined whether or not all the failure points are registered in association with the currently selected path (working path 31) (step 50).
1).

If all the failure points are not registered in association with the working path 31, the determinations for each backup path pattern registered in the path management table 21 (all It is determined whether or not the failure point is registered in association with the path.

In the reference operation to the path management table 21, if there is a corresponding backup path (path in which all the failure points are associated and registered), the path switching unit 1f switches to the backup path. (Step 50
6) If there is no applicable path for all the backup paths (step 503), the service is shut down (step 50).
7).

If all the failure points are registered in association with the working path 31 in the judgment of step 501, the working path 31 is used as it is and waits for the addition of the next failure point (step 508).

In the example shown in FIG. 4, the line identification number of the line 4a in which the failure 42 has occurred is not registered as an item of a bypass unnecessary fault location corresponding to the working path 31, and the input device 1 switches the path. The necessity determination unit 1e determines that the path needs to be switched.

In response to the determination by the path switching necessity determination unit 1e that the path switching is required, the path switching unit 1f refers to the same path management table 21 and the failure 41 and the failure 42 occur. The backup path pattern (5) in which the line identification numbers of the lines 4e and 4a are registered as the items of the bypass unnecessary fault location, that is, the switch destination path capable of conducting the backup path 36 shown in FIG. 3 (f) To switch from the working path 31 (path switching 44).

This path switching is performed so that the packet sent to the relay device 3a in the input device 1 reaches the output device 2 via the backup path 36, that is, from the relay device 3a to the relay device 3b. From device 3b to relay device 3
d, the label of the packet is changed so that the packet reaches the output device 2 from the relay device 3d.

In this way, even when a failure occurs at a plurality of locations within the network work, paths that can be conducted can be selected and switched, and even when a failure occurs at a plurality of locations within the network work, the service interruption time is lost. Can be shortened, so that a more reliable network can be provided.

As described above with reference to FIGS. 1 to 5, in this example, in a network in which three or more routes exist between the input device 1 and the output device 2 of a certain traffic, the input device is 1 and a plurality of backup paths 32 through which the traffic passes between the output device 1 and the output device 2.
38 is set and each line 4 in the network is set in advance.
Number for identifying a to 4h (line identification number ~)
Is allocated, and a set of line numbers (line identification numbers ~) that do not affect communication even if a failure occurs is registered and managed as the path management table 21 for each path 31-38.

When a failure occurs in the network, the device that detects the failure notifies the input device 1 of the line identification number ~ corresponding to the failure location, and the input device 1 receives the notification. By referring to the path management table 21, it is determined whether or not the path needs to be switched, and if necessary, a path that can be conducted is selected from the path management table 21 and switched to that path.

In this way, the working path 31 and the plurality of backup paths 32 to 38 are set between the input device 1 and the output device 2, and when a failure occurs in the network, the device that detects it is detected. Notifies the input device 1 of the line identification number ~ corresponding to the faulty part, and the input device 1 judges from the path management table 21 whether switching is necessary based on the notification, and selects a path that can be conducted if necessary. Then, since the path is switched to, it is possible to switch even when there is a failure at a plurality of points in the network, and it is possible to shorten the service interruption time.

Further, in this example, as shown in the path management table 21 of FIG. 2, the lines 4a to 4 which are not on the path for each path and have no influence on the communication on the path even if a failure occurs.
With the configuration in which the identification numbers from h are registered in association with each other, the backup path selection processing based on the path management table 21 is made efficient.

The present invention is not limited to the examples described with reference to FIGS. 1 to 5, and various modifications can be made without departing from the scope of the invention. For example, as described above, in this example, a network that performs packet transfer by the label switching method by MPLS has been described as an example, but the present invention is also applicable to other packet transfer networks.

Further, in this example, as shown in the path management table 21 of FIG. 2, the lines 4a to 4 which are not on the path and have no influence on the communication on the path even if a failure occurs for each path.
Although the identification number of h is registered in association with each other, the process of selecting the backup path based on the path management table 21 is made efficient, but each path is on the path and a failure occurs. In this case, the identification numbers of the lines 4a to 4h that may affect the communication on the path may be registered in association with each other and used for the switching control.

Further, in this example, the computer configuration of the input device 1 may be a computer configuration without a keyboard or an optical disk drive. Further, in this example, the optical disk is used as the recording medium, but the FD
(Flexible Disk) or the like may be used as the recording medium. Further, regarding the installation of the program, the program may be downloaded and installed via the network via the communication device.

[0050]

According to the present invention, even when a plurality of points in the network fail, the traffic input side device that has been notified of the failure selects a path that can be conducted from a plurality of preset backup paths. It is possible to shorten the service interruption time and provide a more reliable network.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a network provided with a path switching system according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a path management table registered by a path management table registration unit in FIG.

FIG. 3 is an explanatory diagram showing an example of path setting in the network of FIG.

FIG. 4 is an explanatory diagram showing an example of path switching processing in the network in FIG.

5 is a flowchart showing an example of processing operation of the path switching system in FIG.

FIG. 6 is a block diagram showing a configuration example of a conventional MPLS network.

7 is a block diagram showing an example of path switching operation in the network in FIG.

[Explanation of symbols]

1: input device, 1a: path control unit, 1b: path setting unit,
1c: failure occurrence detection unit, 1d: path management table registration unit, 1e: path switching necessity determination unit, 1f: path switching unit,
2: Output device, 3a to 3d: Relay device, 4a to 4h: Each line (identification number ~), 21: Path management table, 3
1: working path, 32 to 38: backup path, 41, 42: failure, 43: failure notification, 44: path switching, 61: input device, 62: output device, 63a to 63d: relay device, 7
1: path (“working path”), 72: path (“spare path”), 73: failure, 74: failure notification, 75: path switching.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5K014 CA06 FA09 FA15                 5K030 GA12 HA08 HC01 JA11 LB08                       MD02                 5K051 AA01 AA02 BB00 DD09 DD11                       FF11 FF16 GG06 HH27 LL02                       LL07

Claims (13)

[Claims] 1. A path switching system in a network in which three or more routes exist between a traffic input device and a traffic output device, and a path is set in the routes to allow traffic to pass through. And setting means for setting two or more spare paths, registration means for registering information in which each path is associated with the identifier of each line that is not on the path, and occurrence of failure of one or more lines. Detection means to detect,
When the detection means detects the occurrence of a line failure, the registration information of the registration means is referred to, and if the identifier of the failure occurrence line is not registered in association with the currently selected path, switching to another path is performed. In response to the judgment means for judging that the above is necessary and the judgment that the path switching is necessary by the judgment means, the registration information in the above registration means is referred to, and the path associated with the identifier of the faulty line is identified. A path switching system comprising a switching means for selecting and switching paths. 2. A path switching system in a network in which there are three or more routes between a traffic input device and a traffic input device, and paths are set in the routes to allow traffic to pass. And setting means for setting two or more spare paths, registration means for registering information in which each path is associated with the identifier of each line on the path, and occurrence of failure of one or more lines. Detection means to detect,
When the detection means detects the occurrence of a line failure, the registration information in the registration means is referred to, and if the identifier of the failure occurrence line is registered in association with the currently selected path, switching to another path is performed. In response to the judgment means for judging that it is necessary and the judgment that the path switching is necessary by the judgment means, the registration information in the registration means is referred to, and the path not associated with the identifier of the faulty line is selected. A path switching system comprising a switching means for selecting and switching paths. 3. A path switching system in a network in which three or more routes exist between a traffic input device and a traffic input device, and paths are set in the routes to perform packet transfer by label switching. Working path and 2
The setting means for setting the above-mentioned backup path, the registration means for registering the information associated with the identifier of each line not on the path for each path, and detecting the occurrence of failure of one or more lines When the detecting means and the detecting means detect the occurrence of a line failure, the registration information in the registration means is referred to, and if the identifier of the failure occurrence line is not registered in association with the path currently used, another Corresponding to the judgment means for judging that it is necessary to switch to the path and the judgment that the path switching is necessary by the judgment means, the registration information of the registration means is referred to, and the identifier of the faulty line is associated. A path switching system for selecting a selected path and switching the path. 4. A path switching system in a network in which there are three or more paths between a traffic input device and a traffic output device, and paths are set in the routes to perform packet transfer by label switching. Working path and 2
The setting means for setting the above-mentioned backup path, the registration means for registering the information associated with the identifier of each line on the path for each path, and detecting the occurrence of failure of one or more lines When the detecting means and the detecting means detect the occurrence of a line failure, the registration information in the registration means is referred to, and if the identifier of the line in which the failure has occurred is registered in association with the path currently used, another Corresponding to the judgment means for judging that it is necessary to switch to the path and the judgment that the path switching is necessary by the judgment means, the registration information of the registration means is referred to, and the identifier of the faulty line is associated. A path switching system comprising: a switching unit that selects a path that has not been opened and switches the path. 5. A path switching system in a network in which there are three or more paths between a traffic input device and a traffic output device, and paths are set in the routes to perform packet transfer by label switching. Working path and 2
The means for setting the above-mentioned backup path, the means for detecting the failure of the line that has occurred on the currently selected path, and the means for detecting the failure of the line, the failure is detected from each of the set paths. A path switching system comprising means for selecting a path that does not pass through a line and switching the path. 6. The computer according to any one of claims 1 to 5.
A program to be executed as each unit in the path switching system according to any one of 1. 7. A path switching method in a network in which there are three or more routes between a traffic input device and a traffic input device, and paths are set in the routes to allow traffic to pass. And two or more spare paths are set, information for each path is associated with the identifier of each line that is not on the path, and one or more paths between the traffic input device and output device are registered. When a line failure occurs, the input device refers to the registered information, and if the line identifier of the failed line is not registered in association with the currently used path, switch to another path. Is determined to be necessary, and the path is switched by referring to the registered information and selecting the path associated with the identifier of the line in which the failure has occurred. 8. A path switching method in a network in which there are three or more paths between a traffic input device and a traffic input device, and paths are set in the routes to perform packet transfer by label switching. A working path and two or more backup paths are set, information for each path is associated with the identifier of each line on the path, and information is registered between the input device and the output device of the traffic. When a failure occurs in one or more lines, the input device refers to the registered information, and if the identifier of the failed line is registered in association with the currently used path, another path The method for switching paths is characterized in that it is determined that it is necessary to switch to, and the path is switched by referring to the above registered information and selecting a path that is not associated with the identifier of the line in which the failure has occurred. . 9. A path switching method in a network in which there are three or more routes between an input device and an output device of traffic, and paths are set in the routes to perform packet transfer by label switching. A working path and two or more backup paths are set, information for each path is associated with the identifier of each line that is not on the path, and information is registered between the traffic input device and output device. When one or more line failures occur, the input device refers to the registered information, and if the identifier of the failed line is not registered in association with the currently used path, another path is registered. A path switching method is characterized in that it is determined that it is necessary to switch to, and the path switching is performed by referring to the registered information and selecting the path associated with the identifier of the line in which the failure has occurred. 10. A path switching method in a network in which three or more routes exist between a traffic input device and a traffic input device, and paths are set in the routes to perform packet transfer by label switching. A working path and two or more backup paths are set, information for each path is associated with the identifier of each line on the path, and information is registered between the input device and the output device of the traffic. When one or more line failures occur, the input device refers to the registered information, and if the identifier of the failed line is registered in association with the currently used path, another path is registered. A path switching method is characterized in that it is determined that it is necessary to switch to, and the path switching is performed by referring to the registered information and selecting a path that is not associated with the identifier of the line in which the failure has occurred. 11. A path switching method in a network in which three or more routes exist between a traffic input device and a traffic output device, and paths are set in the routes to perform packet transfer by label switching. When a working path and two or more spare paths are set and a line failure that occurs on the currently selected path is detected, a path that does not pass through the failed line is selected from the above set paths. A path switching method characterized by performing path switching. 12. A communication device as the input device in a network, wherein there are three or more routes between a traffic input device and a traffic input device, and paths are set in the routes to perform packet transfer by label switching. And
Setting means for setting a working path and two or more spare paths, registration means for registering information in which each path is associated with the identifier of each line that is not on the path, and a line from another communication device Receiving means for receiving notification of failure occurrence, detecting means for detecting occurrence of failure of the line connected to the own device, detection of occurrence of line failure by the detecting means, or receipt of notification of occurrence of line failure by the receiving means. Corresponding to, the information registered by the registration means is referred to, and if the identifier of the faulty line is not registered in association with the currently used path, it is determined that switching to another path is necessary. Corresponding to the judgment means to perform and the judgment that the path switching is necessary by the judgment means, the information registered by the registration means is referred to and the path associated with the identifier of the faulty line is selected to switch the path. Switching means Communication apparatus characterized by having a. 13. A communication device as an input device in a network in which there are three or more routes between a traffic input device and a traffic output device, and paths are set in the routes to perform packet transfer by label switching. And
Setting means for setting a working path and two or more spare paths, registration means for registering information in which each path is associated with the identifier of each line on the path, and a line from another communication device Receiving means for receiving notification of failure occurrence, detecting means for detecting occurrence of failure of the line connected to the own device, detection of occurrence of line failure by the detecting means, or receipt of notification of occurrence of line failure by the receiving means. Corresponding to the above, referring to the information registered by the registration means, if the identifier of the faulty line is registered in association with the currently used path, it is determined that switching to another path is necessary. In response to the determination means to perform and the determination that the path switching is required by the determination means,
A communication device comprising: a switching unit that refers to the information registered by the registration unit, selects a path that is not associated with an identifier of a failure line, and switches the path.