JPH0528549B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a packet transmission method in a packet-switched network that can prevent an abnormality in packet transmission from expanding in the event of an abnormality in the packet-switched network. .

[Conventional technology]

FIG. 4 shows a packet switching device used in a conventional packet switching network to select a relay path for a relay packet to the next station.
2 is a diagram showing a relay route selection priority order table (hereinafter referred to as a routing table) for each destination receiving station of a relay packet; FIG. In the figure, 20 is a routing table for a certain destination receiving station, 20.1 is a relay number display area with the highest priority in this routing table 20, and 20.2 to 20.m are the second to mth relay number display areas, respectively. This is the relay route number display area with the highest priority.

In a packet transmission system in a so-called conventional fixed detour packet switching network, when a packet is relayed, the routing table 20 corresponding to the destination terminating station of the packet prevents the relay path from being used due to an abnormality in the relay path or an adjacent relay station connected thereto. Select the relay route with the highest priority other than the relay route with
Send a packet. At this time, if the selected relay path is other than the relay path 20.1 with the first highest priority, it is generally said that the packet has been detoured. In this conventional packet transmission method, when a detour occurs in a relayed packet, the detour occurrence is displayed in the header of the packet, and if an abnormality such as congestion occurs in the network, this detour occurrence indication is displayed. Control was carried out such as preferentially restricting packets with a certain number of packets.

[Problem that the invention seeks to solve]

Since the packet transmission method according to the present invention is constructed as described above, unless the packets themselves are regulated when an abnormality occurs in the network, packet relay transmission between originating and terminating stations is performed using a detour route that is completely different from that in normal times. However, since this detour route has a low capacity for relaying detour packets, secondary network abnormalities such as new congestion occurring at this relay route or relay station may occur, and the abnormality may further expand. There was a problem that there was a possibility that

The purpose of the packet transmission method of the present invention is to provide a packet transmission method that can prevent abnormal expansion within a packet switching network and maintain smooth packet transmission within the network.

[Means for solving problems]

In the packet transmission method in a packet switching network according to the present invention, each time a detour occurs during packet relay, the detour count display area set in the header of the packet is increased by +1, and when this value exceeds a predetermined threshold, the detour count display area is increased by +1. In this case, packet transmission between the transmitting station and the receiving station of the packet is restricted for a certain period of time.

[Effect]

The packet transmission method in the packet switching network according to the present invention is such that between originating and terminating stations with many detours,
Since packets are transmitted having a detour count display area for regulating packet transmission, anomalies within the network are prevented from expanding.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the contents of a relay packet. In the figure, 1 indicates a relay packet, 2
is the header section of relay packet 1, and 3 is its information section. Reference numeral 4 indicates a detour count display area set in the packet header section 2. In Figure 2,
5 is a detour count threshold table set for each destination receiving station of relayed packets held by the packet switching device; 5.1
.about.5.n are detour count threshold display areas for each destination receiving station arranged in order of station number. Also,
FIG. 3 is a diagram illustrating an example of a packet switching network configured by a packet switching device that transmits a relay packet 1 having a detour count display area 4 and has a detour count threshold table 5, where 6 is a transmitting terminal, 7 is a is the incoming terminal,
8 is a packet originating station (hereinafter referred to as the originating station), 9 is a packet receiving station (hereinafter referred to as the terminating station), 10,1
1 and 12 are packet relay switching centers (hereinafter referred to as relay switching centers), respectively; 13, 14, 15, and 16 are the first terminals from the originating station 8 and the relay switching centers 10, 11, and 12 to the destination receiving station 9; High-priority relay paths 17, 18, and 19 are second high-priority relay paths to the destination terminating station 9 at the originating station 8 and the relay switching centers 10 and 11, respectively.

Next, a packet transmission method in the packet switching network having the above configuration will be explained.

When the transmitting station 8 relays a packet addressed to the receiving station 9, the relay path 13 in the first priority display area 20.1 of the routing table 20 is unavailable due to a failure or the like, so the second priority display area 20.
2 is selected to relay the packet, and when a detour occurs, the detour count display area 4 for the packet is increased by +1 immediately before the packet is sent.
When the transmitting station 8 generates a relay packet, the detour count display area 4 is set to 0, so the relay path 17
When the packet is sent to , the detour count display area 4 is set to 1. This value is used as the detour count threshold table 5.
The packet is compared with a threshold value for the number of detours to the destination station 9, and if the threshold value is not exceeded, the packet is sent to the relay path 17. Similarly, at the next relay station 10, the routing table 20 for the destination terminating station 9 is
When an attempt is made to select the relay route 14 first, a detour still occurs due to an abnormality, and the relay route 18 is selected, the content of the packet detour count display area 4 is increased by +1. The threshold value in the detour count threshold table 5 is compared with the value in the packet detour count display area 4 (which is 2 in this state), and if the threshold value is not exceeded, the packet is sent to the relay path 18. Furthermore, a detour occurs in the same way at the next relay station 11, and the packet detour count display area 4 is incremented by +1 (in this state it becomes 3) and compared with the detour count threshold. here,
For example, assume that the number of detours exceeds a threshold. At this time, the relay station 11 transfers the packet to the detour relay route 1.
At the same time, the sending station 8 and the receiving station 9 of the packet are notified that the number of detours has exceeded the threshold value by means of an abnormality notification packet. After receiving the abnormality notification packet, the originating station 8 and the terminating station 9 stop sending packets to the other station for a certain period of time.

〔Effect of the invention〕

As described above, according to the present invention, a detour count display area is set for a relay packet, and when the detour count exceeds a predetermined threshold, the packet transmission between the originating and receiving stations is set constant. Since the time is stopped, the packet relay route between the originating and receiving stations continues to include many detour routes.
This has the effect of providing a packet transmission method in a packet-switched network that can prevent anomalies within the network from expanding, such as congestion occurring in detour routes or relay stations.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a relay packet format in a packet transmission method according to an embodiment of the present invention, and FIG. 2 is a state diagram showing a detour count threshold table in a packet transmission method according to an embodiment of the present invention. FIG. 3 is a block diagram showing the structure of a packet switching network, and FIG. 4 is a state diagram showing a routing table corresponding to a destination terminating station used in a general packet switching network. In the figure, 1 is a relay packet, 2 is a header section, 3 is an information section, 4 is a detour count display area, 5 is a detour count threshold table, 8 to 12 are packet switching stations, and 13 is a detour count display area.
19 is a relay route, and 20 is a relay route selection priority table.

Claims (1)

[Claims] 1. A packet switching network consisting of a plurality of packet switching devices has a relay route selection priority table in which the selection priority of the relay route for transmitting the relay packet is set, and the relay packet is sent according to the relay route selection priority table. In a packet transmission method in a packet switching network in which a packet is relayed to a destination receiving station, a detour count display area is set in the header part of the relay packet, and the relay with the highest selection priority is selected as the relay route to which the relay packet should be sent. Each time a detour relay route other than the route is selected, the value in the detour count display area is added by 1, and if the value in the detour count display area exceeds a preset threshold, it is determined that there is an abnormality and a relay packet is transmitted. A packet switching network characterized in that an abnormality notification is sent to a station and a terminating station, and then, for a certain period of time, the originating station and the terminating station that have received the abnormality notification stop transmitting the relay packet. Transmission method.