JPH09331357A - Communication route switch-back control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restore automatically the communication considered to be important by the user with priority to a normal route as to the communication using a bypass route or a communication route in an interrupt state when the network is restored from a fault in the network establishing the communication route automatically. SOLUTION: Switch back priority in combination of switch-back priority and a route state by importance is provided to all communication routes 51-53 established in the communication among terminal container sections 31-36, and a route established at first is registered. Thus, when a fault 71 between nodes 11 and 13 is restored and reservation of a service required to restore the communication route 51 between the terminal container sections 31 and 36 to an original route is disable, the communication route 52 with lower switch- back priority in the bypass state is interrupted and the communication route 51 is established again to the registered route to obtain the normal route.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication route for controlling a process for switching back a communication route in which a line has been detoured or disconnected due to a network failure to the communication route originally established. The present invention relates to a switchback control system, and more particularly, to a communication route switchback control system capable of switching back a communication route in consideration of priority in a network in which a communication route is automatically determined.

[0002]

2. Description of the Related Art Conventionally, this kind of communication route switchback control method is used when a network recovers from a failure state.
The communication using the detour route is used for the purpose of switching to use the communication route that was normally used. Alternatively, it is used for the purpose of recovering a communication that has been disconnected until then so as to use the communication route that was normally used when the network is restored.

For example, in the conventional method, in order to distinguish between a normal communication route (hereinafter referred to as a normal route) and a detour communication route (hereinafter referred to as a detour route), a network designer has in advance. , Register the normal route and the detour route, or register only the normal route. If the line is disconnected due to a network failure, the registered detour route is used, or the detour route is automatically established and communication is resumed. Or, if the detour route cannot be established, it remains disconnected. Then, when the network is restored from the failure, if the detour route has been established, the communication route is temporarily cut off and the communication using the registered normal route is restarted. This method automatically uses, for example, when a line with a low charge is used and a failure occurs in the line, and when the line is switched to a high-price communication line, when the error in the network is restored. It is used to switch back to a cheap communication line. Alternatively, if the network is in a normal state, optimal route selection is performed, and the communication route is established, when the network returns from the abnormal state to the normal state, the communication route automatically returns to the original state. Used to be returned. In addition, the system that automatically establishes a communication route without distinguishing between a normal route and a bypass route does not have this switchback function.

[0004]

The first problem is that, in a network in which a node that constitutes the network automatically determines a communication route between terminals, the communication route from the detour route to the normal route is switched. It means that it cannot be returned. The reason is that the communication route is automatically determined without being aware of the normal route and the detour route, and thus the distinction cannot be made.

A second problem is that when a node constituting a network automatically determines a communication route between terminals and a failure occurs at a plurality of places, a part of the network is restored. Therefore, even if the physical route is restored, the communication route that used the restored route may not be able to be returned to the restored route. The reason is that the service (bandwidth, delay, discard rate) required to establish a normal route communication route by using some or all of the routes that the network is trying to return to by other detour routes. This is because there is a case where it cannot be secured.

An object of the present invention is, in a network for automatically determining a communication route, a communication route capable of returning a detour route or a communication route in a disconnected state to a communication route which has been established at the time of recovery from a network failure. It is to provide a switchback control method.

[0007]

A communication route switchback control system according to the present invention has a network configuration in which a plurality of nodes having a plurality of terminal ports capable of accommodating a user terminal are connected and a service requested by the user. In a network that establishes a guaranteed communication route, means for giving the communication route a route state expressing its state, and a communication route between terminals first established to define the route state. Means for registering
For each communication handled in the network, means for designating a switchback priority indicating the priority of processing for returning to the initially established communication route, and detecting that the network has returned from an abnormal state to a normal state And a means for identifying the route state, prioritizing the communication route having the higher switchback priority, and returning the communication route between the terminals to the communication route established first.

The communication route switchback control method according to the present invention further comprises means for defining a switchback attribute expressing a processing method for returning the communication route between the terminals to the communication route established first, and Means for allocating the switchback priority, which is a combination of the switchback attribute and the route state, to the communication route, and a communication route having a high switchback priority using the switchback priority for the communication route that was initially established. When performing the returning process, if the network cannot secure the service required for the communication route, it is possible to disconnect another communication route having a lower switchback priority that has already been established. Thus, the communication route having the higher switchback priority has means for giving priority to the processing for returning to the communication route established first.

Further, the communication route switchback control system according to the present invention is characterized in that the route state and the switchback priority are:
It has means for managing in a node which terminates a communication route among nodes constituting a network, and activation means for activating a process for returning to the communication route established first in the node where the communication route terminates.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. 1 to 4 are block diagrams of a network showing an embodiment of the present invention.

In the network shown in FIG. 2, a plurality of nodes 11 to 14 each including a terminal accommodating section 31 to 36, a data exchanging section 21 to 24, and control sections 41 to 44 for controlling them are connected to connection lines 61 to 41. The switchback control system according to the present invention is adopted, which has a configuration connected by 65.

The terminal accommodating portions 31 to 36 accommodate interfaces for accommodating the terminals of network users, and the data exchanging portions 21 to 24 connect the nodes and determine the destination of the data of the terminals. .

Terminal accommodating portions 31 to 36 of the nodes 11 to 14
Sends a connection request with another terminal accommodation unit to the control unit 41 in the node.
To 44, the control units 41 to 44 of the respective nodes exchange information with each other and judge whether the service required for communication between the terminal accommodating units can be secured or not. The node is determined and the communication routes 51 to 53 are established. At this time, the terminal accommodating units 31 to 36 define and register the route states of the established communication routes 51 to 53. In the case of FIG. 2, all the registered route states are normal, but when a failure occurs in a part of the network as shown in FIG. 1, the state of the corresponding route is identified as abnormal. Such route status management is performed in the accommodation unit of the terminal related to transmission and reception of each communication.

When the communication routes 51 to 53 are disconnected due to a network failure, such as a node failure or a transmission line disconnection failure, the terminal accommodating sections 31 to 36 request connection to the control sections 41 to 44 in the node again. By performing the communication between these control units, a detour communication route is established, and communication between terminals becomes possible.

Further, in the present embodiment, the control of the processing for switching back the detour route or the communication route in the disconnected state due to the network failure to the normal route, that is, when the switching back control is performed, the processing content is switched back. Define as an attribute. This switchback attribute represents the degree of influence of the communication route that is the processing target on other routes when the switchback process is executed.

Further, when establishing the communication route between the terminals, the switchback priority determined based on the route state and the switchback attribute is defined for all the communication routes between them. Like the route information, this priority information is also registered in the accommodation unit of the terminal related to the transmission / reception of the communication.

Next, the contents of the switchback control method will be described in detail.

First, as the root state, as shown in FIGS. 5 and 6, a normal state 201, a disconnected state 202,
Four states, a detour state 203 and a route unregistered state 204, are defined. FIG. 5 is a block diagram showing the transition relationship of the root states, and FIG. 6 shows the transition conditions of the root states.

The normal state 201 means that the communication route registered in the terminal accommodating section is established as an actual communication route, and the disconnected state 202 means that the communication route is not registered in the terminal accommodating section. However, it means that the communication route is disconnected due to a network failure without being established, and the detour state 203 means that a route different from the communication route registered in the terminal accommodating unit is established as an actual route. The state means a state, and the route unregistered state 204 means a state in which a communication route is not yet registered in the terminal accommodating unit, and thus no communication route is established.

The switchback attribute is "disconnectable" or "undisconnectable" with respect to other communication routes when the network recovers from a failure and switches the communication route in the bypass or disconnected state back to the normal route. Is defined as "conditional", and is defined as a condition "can be disconnected" or "cannot be disconnected" with respect to its own communication route in the switching back processing of another communication route.

Next, the switchback priority is defined for each communication route in two stages of priority 1 and priority 2 based on the combination of the route status and the switchback attribute. The higher the priority number, the higher the priority of the switchback, and the higher the probability that the communication route will switch back to the registered route.

Each of the terminal accommodating units 31 to 36 executes the communication route switchback processing with reference to the switchback priority assigned to the communication route.

A communication route in a normal state does not disconnect its own communication route and does not disconnect other communication routes regardless of whether the switchback priority is 1 or 2.

When the communication route of the switchback priority 1 is in the detour state, there is a possibility that the communication route of itself is disconnected during the switchback process of another communication route. However, other communication routes are not cut off when performing the switching back process of its own communication route.

When the communication route of the switchback priority 2 is in the detour state, there is a possibility that the communication route of itself is disconnected by the switchback process of the other communication route. In addition, another communication route may be disconnected during the process of switching back its own communication route.

When the communication route of the switchback priority 1 is in the disconnected state, the other communication route is not disconnected in the process of switching back the communication route of itself.

When the communication route of the switchback priority level 2 is in the disconnected state, another communication route may be disconnected in the process of switching back the own communication route.

Therefore, the route state of each communication route changes variously depending on the presence / absence of abnormality in the network, the ripple effect of the switchback processing, and the like. Next, the state transition of the communication route will be described with reference to FIGS.

The normal state 201 in FIG. 5 is the normal state 2
01 or the disconnection state 202. As shown in FIG. 6, the transition to the normal state 201 is performed when there is no change in the root state, and the transition to the disconnection state 202 is performed when the line is disconnected due to a network failure. The transition of the route state does not depend on the switchback priority of the communication route.

The cut state 202 in FIG. 5 is the normal state 20.
1, transition to the disconnection state 202 or the detour state 203.

When transitioning from the disconnection state 202 to the normal state 201, as shown in FIG. 6, if the switchback priority of this communication route is 1, the switchback processing is performed without disconnecting other communication routes. , Establish a communication route to the normal route. When the switchback priority of the communication route is 2, another communication route is disconnected as necessary to perform the switchback process, and the communication route is established as the normal route.

When transiting from the disconnection state 202 to the disconnection state 202, as shown in FIG. 6, when the detouring process is executed but there is no detourable route to which the detouring can be performed, or the service cannot be secured, Alternatively, it is performed when the registered communication route is normal but the necessary service cannot be secured to perform the switchback processing, or when the state of the registered route does not change. The transition of the route state is not influenced by the switchback priority of the communication route.

The transition from the disconnection state 202 to the detour state 203 is performed when the detouring process is executed and the detour communication route is established, as shown in FIG. This transition is also not affected by the switchback priority.

The detour state 203 of FIG.
2. Transition to the detour state 203 or the normal state 201.

As shown in FIG. 6, the transition from the detour state 203 to the disconnection state 202 is performed when the line is disconnected by the switchback processing of another communication route whose switchback priority is 2, or this communication route. This is performed when the line is disconnected due to a line failure regardless of the switching back priority of.

As shown in FIG. 6, the transition from the detour state 203 to the detour state 203 is performed when there is no change in the registered route state or when the registered communication route is normal but the necessary service is secured and switched. It is performed when the return processing cannot be performed.

When making a transition from the detour state 203 to the normal state 201, as shown in FIG. 6, if the communication route switchback priority is 1, the switchback processing is performed without disconnecting another communication route, If the switchback priority is 2, other communication routes are disconnected as necessary to perform the switchback processing. Then, the communication route is established on the normal route.

The route unregistered state 204 of FIG. 5 transits to the normal state 201 or the route unregistered state 204.

Route unregistered state 204 to normal state 20
As shown in FIG. 6, the transition to 1 is performed when the attempt to establish the communication route is successful and the route unregistered state 204
The transition to is performed when an attempt is made to establish a communication route but it fails. Each transition is not affected by the switchback priority registered in the communication route.

The route status is managed in the terminal accommodating units 31 to 36 in which terminals related to the communication are accommodated. The terminal accommodating units 31 to 36 register the communication routes 51 to 53 determined when the communication route was first established. The information on the registered communication route is used to determine the route state and the transition condition as shown in FIGS. For example, it is used to restore the communication route in the disconnected state 202 in which the detour processing is not executed after the failure recovery to the normal route and to distinguish the currently established communication route from the detour route or the normal route. It

For the communication route having the switchback priority 1, the switchback process of the communication route is executed in the disconnection state 201 or the detour state 202. At that time, the communication route must be established to the registered route without disconnecting other communication routes. If this switchback priority is 1
If the communication route is in the detour state 203, it is confirmed that the communication route can be established in the normal route, the communication route that is the detour route is disconnected once, and the communication route is reestablished in the normal route. To be done.

Therefore, even if there is no failure in the line of the normal route, the service (bandwidth, etc.) required for the communication between terminals on a certain communication route because another communication route is bypassed.
When the discard rate and delay) cannot be secured, the communication route remains in the disconnected state 202 or the detour state 203.
Further, in the switching back processing of another communication route, the communication route of the priority 1 can be disconnected simply in the detour state 203.

On the other hand, the communication route of the switchback priority 2 is
The communication route switchback processing is executed in the disconnection state 202 or the detour state 203, and if necessary in order to secure the service required for communication between the terminals, the detour state 203
Disconnect other communication routes and establish a normal route. If the communication route of the switchback priority 2 is in the bypass state 203, it is confirmed that the communication route can be established in the normal route, the disconnect route is once cut, and then the communication route becomes the normal route. Reestablished. Further, in the process of switching back another communication route, the communication route having the priority 2 can be disconnected in the detour state 203.
Therefore, when the registered route is recovered from the failure, the communication route is always switched back to the route.

Next, a detailed description will be given of the content of the communication route switchback control method using the switchback priority described above. FIG. 2 is a block diagram showing a network configuration when no failure occurs, and normal routes 51 to 53 are provided between the terminal accommodating units 31 to 36.

The communication route 51 between the terminal accommodating portion 31 and the terminal accommodating portion 36 is a route utilizing the connection line 61 and the connection line 64, and the communication route 52 between the terminal accommodating portion 32 and the terminal accommodating portion 34 is connected. The route using the line 63 and the communication route 53 between the terminal accommodating unit 33 and the terminal accommodating unit 35 are established in the route using the connection line 64, respectively. In addition, the route information regarding the communication routes 51 to 53 is the terminal accommodation unit 31 to which the communication routes 51 to 53 terminate.
It is registered in 36. The route information includes information about the node through which the communication route passes and the input port and output port of the node.

The bandwidths used by the respective communication routes are all the same size, and are half the bandwidth available in one connection line, and the connection lines 61 to 65 connecting between the nodes.
Have the same transmission capacity.

FIG. 1 shows communication routes 51 to 53 after the line faults (71, 72) occur on the connection lines 61 and 63 from the normal state of the network shown in FIG. It is the figure shown.

When the faults 71 and 72 shown in FIG. 1 occur, the route state of the communication routes 51 and 52 is the normal state 2
From 01 to the disconnected state 202, the terminal accommodating part 31 or the terminal accommodating part 36 for the communication route 51, and the terminal accommodating part 32 or the terminal accommodating part 34 for the communication route 52.
Requests the reestablishment of the communication route to the control unit of each node.

As a result of the detouring process of the communication route by the exchange between the control units of the respective nodes, the communication route 51 between the terminal accommodating unit 31 and the terminal accommodating unit 36 is reestablished to the route using the connection line 65. The communication route 52 between the terminal accommodating unit 32 and the terminal accommodating unit 34 is reestablished to the route via the node 13 by using the connection line 62 and the connection line 64. The route states of the reestablished communication routes 51 and 52 are changed from the disconnection state 202 to the detour state 203.

First, in the description of FIG. 1, the communication route 5
It is assumed that 1 is set to the switchback priority 2, the communication route 52 is set to the switchback priority 1, and the communication route 53 is set to the switchback priority 2.

Fault 71 between node 11 and node 13
When the communication is restored, the communication route 51 between the terminal accommodation unit 31 and the terminal accommodation unit 36 is the communication route 52.
4 is used to enter the detour state 203, so that the band necessary for the normal route shown in FIG. 2 cannot be secured and the normal route is not returned. Therefore, based on the switchback priority 2, the communication route 52 in the bypass state 203 with the switchback priority 1 is disconnected, the route is disconnected using the connection line 65 of itself, and then the connection line that is the normal route. 6
A communication route 51 using 1 and the connection line 64 is established. Then, the route state of the communication route 51 is changed from the detour state 203 to the normal state 201, the disconnected communication route 52 is changed from the detour state 203 to the disconnected state 202, and the communication route switching back processing is completed. FIG. 3 is a block diagram showing the state of the network after the above processing is executed.

In FIG. 1, the communication route 51 is switched back to the priority level 1 and the communication route 52 is switched back to the priority level 1.
In addition, it is assumed that the communication route 53 is set to the switchback priority level 2.

When the fault 71 between the node 11 and the node 13 is recovered in the same manner as described above, the communication route 51 between the terminal accommodating section 31 and the terminal accommodating section 36 becomes the communication route 52.
2 is in the detour state 203 using the connection line 64, the band necessary for returning to the normal route shown in FIG. 2 cannot be secured, and the normal route is not returned. Furthermore, since the communication route 51 is set to the switchback priority level 1, the communication route 51 does not disconnect the other communication route in the switchback processing. Therefore, the connection line 6 which is a normal route
The communication route using 1 and the connection line 64 is not established, and the communication route 52 remains in the detour state 203. FIG. 4 is a block diagram showing the state of the network after the above processing is executed.

FIG. 7 is an example of a flow chart applied when newly establishing a communication route in the present invention.

When a new communication route is established, the terminal requests the terminal accommodating section to specify a partner terminal with which communication is desired, a service (bandwidth, delay, discard rate, etc.) requested to be guaranteed in the network, and The switchback priority is designated (step 401).

These pieces of information are registered in the terminal accommodating section (step 402). At this time, the route state of the new communication route is registered in the terminal accommodating section as the route unregistered state 204. Then, the terminal accommodating unit that has received the request for establishing the communication route from the terminal requests the control unit of the node to establish the communication route (step 403).

The control unit of the node communicates with the control units of other nodes in the network to determine a communication route suitable for the service requested by the terminal (step 40).
4). It is judged whether or not the route is established (step 405), and when the communication route is established, the control unit of each node gives the service of the communication route passing through the data exchange unit of its own node and the switchback priority. And are remembered.
Then, the control unit of the node notifies the terminal accommodation unit that the communication route has been established. (Step 408).

The terminal accommodating section, which has received the notification of the establishment of the communication route, registers the information of the decided communication route, changes the route state from the route unregistered state 204 to the normal state 201 (step 409), and performs communication. Restart (step 4)
10).

If it is determined in step 405 that the communication route has not been established, the control unit notifies the terminal accommodating unit that the route has not been established (step 411), and the terminal accommodating unit changes this route state to the route unregistered state 204. The processing is completed as it is, and if necessary, the terminal user is notified that the communication route cannot be established (step 412).

FIG. 8 is a flow chart exemplifying the content of the communication route switchback control system.

When the network recovers from the line failure (step 501), the control unit detects this and notifies the terminal accommodation unit of the fact. (Step 502).

In the terminal accommodating section, the route state is the detour state 20.
The communication route which is 3 or the disconnection state 202 is searched, and the switching back process is sequentially started to the searched communication route. (Step 503).

The terminal accommodating section asks the control section whether or not the route in which the communication route is registered is normal with respect to the communication route in which the switchback process is activated, that is, whether or not the route can be physically established. Inquire about it. (Step 504).

The control unit that has received the inquiry exchanges with the control units of other nodes, confirms whether the communication route being inquired is normal, and notifies the terminal accommodating unit of the result (step 505).

The terminal accommodating section, which has received the above notification, informs the control section if the communication route inquired is normal.
A request for switching back the communication route is made so as to establish the inquired communication route (step 508). If the inquired communication route is not normal, the route state does not change, other route states are searched for the detour state 203 or the disconnected state 202, and the retrieved communication route is sequentially switched back. The process is activated (step 503).

Upon receiving the request for the switchback processing from the terminal accommodating section, the control section exchanges between the control sections of the respective nodes to judge whether or not the above request can be accepted. Establish. Then, the control unit notifies the terminal accommodating unit of the result regardless of whether the communication route is established (step 509).

The terminal accommodating section, which has received the above notification, judges whether or not the communication route is established in the normal route (step 5).
10) If it is established, the route state of the communication route is changed to the normal state 201, and if there is a communication route disconnected by the switching back process of this communication route, the route state is changed to the disconnected state 202 (step). 513),
Communication is restarted (step 514). Step 51
As a result of the judgment of 0, if the communication route is not established in the normal route, the route state does not change, and the other communication route is searched for the communication route in the detour state 203 or the disconnected state 202, and the retrieved communication route Then, the switchback processing is sequentially started (step 503).

Then, the process (step 503) for the next communication route in the bypass or disconnection state is repeated.

FIG. 9 shows step 5 of the flow chart of FIG. 8 which illustrates the contents of the communication route switchback control method.
It is a flow chart explaining operation of a control part of 09 in detail.

The control unit, which has received the request for switching back the communication route from the terminal accommodating unit, exchanges information with the control units of other nodes, and the normal route uses services (bandwidth, delay) necessary for communication using the route. , Discard rate, etc.) and search for a communication route in the detour state 203 that uses part or all of the normal route. (Step 601).

Then, the control unit judges whether or not the communication route can be switched back without disconnecting the other communication route (step 602), and if possible, whether or not the own communication route is in the detour state. Confirm whether or not (step 61
9) If it is in the detour state, it disconnects its own route once (step 622) and establishes the communication route to the normal route without affecting other communication routes (step 61).
7) and notifies the terminal accommodating section of the processing result (step 618). As a result of the above confirmation (step 619), when the own route is not in the detour state but in the disconnected state, the communication route is established to the registered route without affecting other communication routes (step 617). The processing result is notified to the terminal accommodating section (step 618).

As a result of the judgment (step 602), if it is necessary to disconnect another communication route, the switchback priority of the communication route for executing the switchback processing is checked (step 605).

As a result of checking the switchback priority, if another communication route cannot be disconnected, the switchback processing is stopped and the processing result is notified to the terminal accommodating section (step 618). If another communication route can be disconnected, the communication route to be disconnected is determined from the retrieved bypassed communication routes (step 608).

The control unit determines whether or not there is a communication route to be disconnected (step 609), and there is no communication route to be disconnected, or even if there is, a communication route for executing the switchback process is established. If the necessary service cannot be secured, the switchback processing is stopped and the processing result is notified to the terminal accommodating unit (step 618).

If there is a communication route to be disconnected,
It is confirmed whether or not its own communication route is in the detour state (step 612).

As a result of the above confirmation, if the own communication route is not in the detour state, the communication route which is determined to be disconnected is disconnected (step 616), and the communication route is established in the registered route (step 617). The processing result is notified to the terminal accommodation unit (step 618).

As a result of the confirmation in the step 612, if the own communication route is in the detour state, the own communication route is temporarily cut off (step 615), and the communication route which has been decided to be cut off is cut off (step 616). A communication route is established in the registered route (step 617), and the processing result is notified to the terminal accommodating section (step 618).

When the communication route is established during the switchback process, the route state of the communication route for switching back is confirmed (steps 612 and 619). Disconnect itself (step 615, step 62)
2) If there is a communication route determined to be disconnected, the communication route is disconnected (step 616) and the communication route is established to the registered route (step 617).

If there is a communication route in the detour state 203 or the disconnected state 202, the terminal accommodating section repeatedly executes the switchback processing. In addition, if the communication route cannot be switched back by the switchback process once, the restart of the switchback process is requested by the terminal accommodating unit at an interval, or
Alternatively, the terminal accommodating unit makes a request to the control unit when a notification of a change in the network topology is received from the control unit, or a request is made in a combination of both.

[0080]

As is apparent from the above, according to the present invention, in a network for automatically determining a communication route, a communication route that is a detour route when the network is restored from a failure or a communication route in a disconnected state Can be returned to its normal route.

Further, when the communication route which the user wants to preferentially perform the switchback when the network is recovered from the failure uses the detour route or the disconnected communication route is used, Even if the other communication route in the detour state is disconnected, the communication route is prioritized to restore the communication to the normal route, so it is important for the user to return to the normal route before the failure occurs. It is possible to return to the communication route.

Further, when a failure occurs at a plurality of places on the network, a normal route can be physically established and restored to a normal route by recovering at several places even if not all the failures on the network are recovered. Therefore, if the network recovers from the failure state, all communication routes are automatically returned to normal routes, and the network that establishes the communication route automatically retains the optimal communication route established first, There is no possibility that a communication route cannot be established due to recovery from a failure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a communication route when a line failure occurs in FIG.

FIG. 2 is a block diagram showing a configuration of a network provided with a communication route switchback control system according to an embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a communication route when a failure is recovered in FIG.

FIG. 4 is a block diagram showing another example of the communication route when the failure is recovered in FIG.

5 is a block diagram showing a transition relationship of route states of the communication route of FIG.

FIG. 6 is a state transition table showing conditions for transition of the root state of FIG.

FIG. 7 is a flowchart illustrating an operation at the time of establishing the communication route of FIG.

FIG. 8 is a flowchart showing an example of a switchback control method in the network of FIG.

9 is a flowchart illustrating the control operation of FIG. 8 in more detail.

[Explanation of symbols]

 11-14 nodes 21-24 data exchange section 31-36 terminal accommodating section 41-44 control section 51-53 communication route 61-65 connection line 71, 72 failure location

Claims (4)

[Claims] 1. A communication route revertive control of a network having a network configuration in which a plurality of nodes having a plurality of terminal ports capable of accommodating user terminals are connected and establishing a communication route in which a service requested by a user is guaranteed. In the method, means for giving a route state expressing the state to the communication route, further means for registering a communication route between the terminals first established in order to define the route state, in advance, For each communication handled in the network,
A means for designating a switchback priority indicating the priority of the processing for returning to the initially established communication route, a means for detecting that the network has returned from an abnormal state to a normal state, and identifying the route state. And a means for returning the communication route between the terminals to the communication route established first by prioritizing the communication route having the higher switchback priority. 2. A unit for defining a switchback attribute expressing a processing method for returning a communication route between the terminals to the communication route established first, and the combination of the switchback attribute and the route state. Means for assigning a switchback priority to a communication route, and a process for returning a communication route having a high switchback priority to the communication route established first using the switchback priority, if the network is If the service required for the route cannot be secured, it is possible to disconnect another communication route having a lower switchback priority that has already been established, so that the communication having the higher switchback priority can be achieved. 2. The communication route switchback control method according to claim 1, further comprising: means for giving priority to processing for returning to a communication route established first for a route. 3. A means for managing the route status and the switchback priority in a node which terminates a communication route among a group of nodes constituting a network, and the communication route which is initially established in the node where the communication route terminates. 3. The communication route bypass control method according to claim 2, further comprising a starting unit that starts a process for returning to the above. 4. The communication route switchback control method according to claim 1, wherein the abnormal state of the network is a line disconnection or a node failure in the communication route established first.