JPS5925537B2 - Route reversal method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a route selection method for a communication network consisting of a plurality of nodes and communication paths interconnecting them.
The present invention relates to a method for switching to a detour route when the main route is unavailable and a method for switching back to the main route when the main route is restored.

Conventionally, such communication networks include telephone switched networks, packet switched networks, and dedicated direct line computer networks, but each of them has the following drawbacks when the route is unavailable.

That is, in a switched telephone network, communication may be interrupted and a call must be made again. In a packet-switched network, it is necessary to trace back to the source node and change the route. Note that routing control is not necessary in a dedicated direct line computer network or network because end-to-end communication is performed. The present invention has been made in view of the above conventional drawbacks, and one object thereof is to enable a relay node to select a detour route and switch back to the main route.Other objects of the present invention are The object of the present invention is to realize a route switchback method that switches back from the detour route to the main route immediately after the main route is restored.

The details of the present invention will be explained below with reference to Examples. FIG. 1 is a block diagram showing an example of the configuration of a network to which the present invention is applied. Nodes PA, PB, PC indicated by circles...
...PF is each information processing device within the communication network, and these are composed of a plurality of information processing devices. Node PA is a source node that transmits information within a communication network, and node PE is a destination node or receiving node that receives information. The nodes are connected to each other by lines. The communication path from the source node to the destination node is called a route, and the nodes on this route are called relay nodes. In Fig. 1, there are multiple routes from the source node PA to the destination node PE, but in this case (;) the source node PA
first forwards the information to an adjacent node on the optimal route determined between its own node and the destination node, and (:i) the adjacent node subsequently forwards the information to the destination node determined between its own node and the destination node. Transfer the information to an adjacent node on the optimal route, and then transfer the information to the final destination node by passing through an adjacent relay node as described above. The optimal route determined by each node in this way is called a main route, and the other routes are called detour routes.

The main route is formed, for example, from the source node PA to the destination node PE via the relay nodes PB, PCl, and PD so that the source node and the destination node are connected by the shortest route. At this time, PA-PF-PE and P
A-PB-PF-PE is a detour route. Generally, when communicating within a communication network, the communication network is designed based on the traffic balance of the entire communication network, transfer time (turnaround), and node service hours, and as part of this, The optimal routes, namely the main route and detour route, are designed. FIG. 2 is a block diagram showing the configuration of the information processing device 1 in each node, where 2 is a route control unit that selects an outgoing line based on a route designation instruction from a network management unit, and 3 is a route control unit 2. a network management unit that manages the status of nodes and lines based on route status information reported from the network management unit and instructs the route control unit 2 about the route to be used;
4 is a communication control unit that transfers data and control commands on a line.

As shown in FIG. 1, if there is no fault within the network, data communication is performed via the main route LM that is uniquely determined by the source node and destination node.

At this time, for example, as shown in FIG. 3, if a failure occurs in the node PD and it becomes unusable, the network management unit 3 of the node PC refers to the display control table for the presence or absence of a detour route to the destination node PE. , upon confirming that no detour route exists, notifies node PB that the main route is no longer available. Upon receiving this notification, the network management unit 3 of the node PB refers to the display control table indicating the presence or absence of a detour route to the destination node PE, as in the case of the node PC. Node PB
When the network management section 3 confirms the existence of the detour route PB-PF, it instructs the route control section 2 to select the detour route PB-PF. In other words, according to the present invention, in a general communication network including a large number of relay nodes, a node that receives notification from the downstream side that the main route is unusable checks whether there is a detour route from its own node to the destination node and takes the detour route. If there is a route, it is selected, and if there is no detour route, a notification that the main route is unusable is forwarded to a further upstream node.

In this way, the notification of the unavailability of the main route is sent to the source node (
The node P in Fig. 3 is transferred to the upstream node).
At B, the route control unit 2 selects the detour route PB-PF based on the designation of the network management unit 3, and the communication control unit 4 sends data to the destination node PE on the detour route PB-PF.

Relay node PF that received this data transfers it to route P
Transfer to destination node PE via FPE. Next, the network management unit 3 of the node PB instructs the route control unit 2 to send a command requesting a main route recovery notification response onto the main route PB-PC, and receives instructions from the route control unit 2. Upon receiving the request, the communication control unit 4 sends a main route recovery notification request command onto the main route PB-PC.

This command is relayed by the node PC and then further
D, but if node PD is still in a failed state, this command is ignored at node PD. Therefore, the node PB does not receive a response to the recovery notification request command, but the network management unit 3 of the node PB sends the main route recovery notification request command to the main route at predetermined time intervals at appropriate intervals until it receives a response to the recovery notification request command. Continue sending out on route. Now, when the failure of the node PD is recovered, the node PD transfers the main route recovery notification request command issued from the node PB to the destination node PE, as shown in FIG.

Upon receiving this, the network management unit 3 of the destination node PE forwards a response indicating that the own node is normal to the PB. The network management unit 3 of the node PB that received this response instructs the route control unit 2 to transfer the data to the destination node PE via the main route PB-PC again, and the communication control unit 4 Force data to be sent on the route. As soon as the main route is restored in this way, the route is switched back from the detour route to the main route. As explained in detail above, according to the present invention, when the main route is unavailable,
This configuration has the advantage that the use efficiency of the communication network is improved because the relay node can select and switch the detour route without tracing back to the source node. In addition, since the configuration is configured to switch back to the main route as soon as the main route is restored, the source node can continue transmitting without being aware that a certain partial area is unavailable, and it also prevents the load balance of the communication network from becoming unbalanced. It has the advantage of being extremely small.

[Brief explanation of the drawing]

1, 3 to 5 are block diagrams of a data communication network to which the present invention is applied, and are for explaining the operation of the present invention, and FIG. 2 is a diagram of nodes PA to PF in FIG. FIG. 2 is a block diagram showing an example of the internal configuration. 1, PA, PB, PC, PD, PE, PF...Node, 2...Route control unit, 3...Network management sleep 4...・Communication control unit.

Claims (1)

[Claims] 1. In a route selection method for a communication network consisting of multiple nodes and communication paths that interconnect them, each relay node detects a failure that occurs on the main route closer to the destination node than its own node, or means for receiving a notification regarding failure detection from an adjacent node on the destination node side; means for checking whether there is a detour route from the own node to the destination node after the failure is detected or notified; The route is switched to the detour route, and a main route recovery notification request command is sent to the destination node on the main route at a predetermined period, and when a response to the command is received, the route is switched back from the detour route to the main route. means for transmitting the command and a response to the command onto the main route; and means for transmitting the notification regarding the failure detection to an adjacent node closer to the source node than the local node when the detour route does not exist. A route switchback method, characterized in that the destination node includes means for transmitting a response on the main route when receiving the main route restoration notification request command.