JPH0376621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a routing control system in a packet switching network.

(Prior art) Conventionally, in a packet switching network, relay packet routing control at a relay station composed of a distributed control device has been divided into functions whose main function is selection of outgoing relay routes1. The configuration involved only one device. Therefore, if a failure occurs in the transmission line that connects packet switching equipment or the packet switching equipment, and the switching equipment or transmission circuit becomes unusable, the adjacent station where the failure occurred will be affected by the failure as described below. was.

FIG. 2 is a conceptual diagram of a function-sharing type distributed control device in a packet switching network. Device a1 is a device whose main function is to select an outgoing relay route, and devices b,
Devices c, d, 2, 3, and 4 are connected to device a1 and transmit and receive packets to and from the opposite station via lines.

If we consider the case where a line failure occurs on the line connected to device b2, at the time of occurrence, storage processing is in progress in device b2, and the packets that were about to be output to the outgoing line of device b2 are routed under the control of routing. As a result, the packet ended up being lost. Also, at the time of the failure, the storage process is in progress in the device d4,
A packet whose destination outgoing line is the outgoing line of device b2 is taken out from device d4, once processed by device a1, and then sent back to device d4, and sent to device d4.
This resulted in a large delay time before reaching the receiving station.

In this way, conventionally, when a failure occurs in a transmission line or packet switching equipment, neighboring stations are affected by the failure, resulting in lost packets,
There were several drawbacks, such as packets having a long delay before arriving at the destination station, and a large load being placed on equipment involved in routing control.

(Object of the Invention) The object of the present invention is to provide a routing control method in a packet switching network that eliminates lost packets, prevents an increase in packet arrival delay time, and prevents overload on devices related to routing control. It's about doing.

(Structure of the Invention) According to the present invention, there is a higher-level device whose main task is to select an outgoing relay route in a packet switching network, and a first and second-level device connected to the higher-level device and which transmits and receives packets to and from the opposite station via a line. In a relay station configured with a functional distributed control device consisting of a second lower-level device, the higher-level device that selects the outgoing relay route selects the outgoing relay route based on the destination station destination information attached to the received relay packet. When selecting a relay route and detecting that selection is not possible due to a fault occurring in a line corresponding to the outgoing relay route, the higher-level device sends a relay route selection-disabled signal to the first and second lower-level devices. In addition, regarding the relay packet that is being stored in the first lower-level device connected to the line corresponding to the outgoing relay route in which the failure has occurred and the relay route cannot be selected, the incoming relay that received the relay packet When the second lower-level device connected to the line corresponding to the other incoming relay route receives the relay route selection disable signal from the higher-level device, If a relay packet is taken out because the relay route cannot be selected because it is being stored in the second lower-level device, the relay packet is sent back to the incoming relay route from which it was received and is re-relayed at the opposite front-stage station. A routing control method for a packet-switched network is obtained.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram of a packet switching center which is a function-sharing type distributed control device for explaining one embodiment of the present invention. A device a1 whose main task is to select an outgoing relay route, and devices b, c, d, 2, 3, and 4 connected to the device a1 and transmitting and receiving packets to the opposite station via a line using the HDLC protocol. configured. Furthermore, lines connecting to other exchanges are connected to devices b, c, d, 2, 3, and 4.

For convenience of explanation, it is assumed that the line connected to device b2 has failed and is no longer usable. As a result, device b2 determines that a failure has occurred since it is no longer able to send or receive packets to and from the opposite station. Then, the device a1 recognizes the occurrence of a failure in the line corresponding to the outgoing relay route via the device b2, and immediately sends a relay disable signal indicating this to the devices b, c, d, 2,
Send to 3 and 4. When this signal is received, the packets being stored in devices b, c, d, 2, 3, and 4 are stored in the storage device of each device. Packets whose delivery has not been confirmed are retrieved from each storage device, and device b2, which recognizes the line failure and receives the relay failure signal, sends the packet back to device a1 to prevent the packet from being lost, and device c. , d, 3, and 4 receive the relay-disabled signal and directly send the packet back to the input relay route that received the packet without going through device a1. Then, the other switching center or device a1 that receives the returned packet performs re-routing to the destination destination station.

(Effects of the Invention) As explained above, the present invention provides a system for transmitting packets between a higher-level device whose main task is to select an outgoing relay route in a packet-switched network, and an opposing station connected to the higher-level device via a line. When a relay station consisting of a function-sharing distributed control device consisting of first and second lower-level devices that transmit and receive data detects that the outgoing relay route cannot be selected, the line corresponding to the outgoing relay route in which the failure has occurred The relay packet that is being stored in the first lower-level device connected to the router and is unable to select a relay route is sent via the higher-level device to the second lower-level device connected to the line corresponding to the input/relay route. Relay packets that are being stored in the device and are retrieved because the relay path cannot be selected are sent back to the opposing front-stage station without going through the higher-level equipment, and are re-relayed at this front-stage station, thereby eliminating lost packets. This has the effect of preventing an increase in packet arrival delay time and preventing overload on devices involved in routing control.

Particularly when handling online control information in a packet-switched network, there are strict requirements to prevent data loss and delay in packets, and the effects of the present invention are significant.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a function-sharing type distributed processing apparatus for explaining an embodiment of the present invention, and FIG. 2 is a conceptual diagram of a function-sharing type distributed processing apparatus for explaining a conventional one. 1...A device a whose main function is to select an outgoing relay route, 2, 3, 4...A device b, c, d that transmits and receives packets to and from the opposite station via a line.

Claims (1)

[Claims] 1 Consists of a higher-level device whose main task is to select an outgoing relay route in a packet-switched network, and first and second lower-level devices that are connected to the higher-level device and transmit and receive packets to and from the opposite station via a line. In a relay station configured with a function-sharing type distributed control device, the higher-level device selects an outgoing relay route based on the destination station destination information attached to the received relay packet, and selects the outgoing relay route of the line corresponding to the outgoing relay route. When detecting that selection is not possible due to the occurrence of a failure, the higher-level device sends a relay route selection-disabled signal to the first and second lower-level devices, and connects to the line corresponding to the outgoing relay route where the failure has occurred. A relay packet that is taken out because the first lower-level device is in the process of storing it and cannot select a relay route is sent back to the incoming relay route from which it was received, and is re-relayed at the opposite previous stage station, and the other When the second lower-level device connected to the line corresponding to the input/relay route receives the relay-route-selectable signal from the higher-level device, the second lower-level device is in the middle of storage processing and cannot select the relay route. A routing control system in a packet switching network, characterized in that the relay packets taken out are sent back toward the incoming relay route from which the relay packets were received and are re-relayed at the opposing upstream station.