JPH037299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a packet transmission method in a packet switching network.

The packet switching method is a type of store-and-forward, in which information is not directly sent and received between terminals, but the exchange receives information sent from the originating terminal, stores it in memory, and transfers it within the network at high speed. This method is used to send the message to the receiving terminal.

Information transferred within the network is divided into blocks of a certain length, and each block is configured into a packet with a header containing control information necessary for transfer, such as destination information and error control information.

[Conventional technology]

In the conventional packet transmission method in a packet switching network, when a packet is relayed, when the relay route to the next station becomes unusable due to an abnormality in the relay route or the relay station connected to it, in other words, packet switching is performed. If the packet cannot be transmitted to the destination terminating station no matter how it is detoured within the network, the packet that cannot be detoured is discarded, and the packet is transferred to the originating station of the packet and the terminating station. Notify the station that detouring is not possible, and thereafter restrict packet transmission between the sending station and the receiving station for a specified period of time, or when receiving relayed packets to the next station or later,
If the number of relay stages of the packet up to that point exceeds the predetermined threshold for the number of relay stages, the packet that has become unrelayable is discarded as a relay failure has occurred, and the packet is sent to the originating station and destination station of the packet to report that the relay failure has occurred. After that, packet transmission between the sending station and the receiving station was restricted for a predetermined period of time.

[Problem that the invention seeks to solve]

In the conventional packet transmission method as described above, the transmission paths that can be detoured for each destination receiving station are stored in a relay path selection table along with their usage priority. Transmission routes with high priority become unusable one after another, and only transmission routes with low priority, that is, transmission routes that are not expected to receive enough traffic to continuously transmit packets destined for the destination station, remain usable. Even if there is a detour, the packet will be transmitted using this detour transmission path, so if such transmission continues, due to this detour transmission,
As a result, many transmission lines and relay stations are monopolized,
As a result, there was a problem in that there was a risk that abnormalities in the packet switching network would spread. Furthermore, if only relays with a large number of relay stages remain, many transmission paths and relay stations will be occupied for this wasteful relay transmission, resulting in abnormal expansion of the packet switching network. There was a problem that there was a risk of Furthermore, if a packet is discarded because it is determined that it cannot be detoured because there are many detours, or that it cannot be relayed because the number of relay stages is large, retransmission within the network will inevitably occur, which may increase unnecessary load.

This invention was made in order to solve the above-mentioned problems, and the network is designed to continuously use a transmission path that has a low priority, that is, it is not expected that the traffic of detour packets will continue. The purpose is to prevent abnormalities from expanding and maintain smooth packet transmission in a packet switching network.

[Means for solving problems]

In this invention, a threshold value is set for the priority order of the relay route stored in the relay route selection table for each destination station, and when a relay route with a priority value lower than the threshold value is selected when a packet is relayed by a packet switching device, , the packet is relayed as is, but thereafter packet transmission between the packet originating station and the receiving station is restricted for a predetermined period of time. In addition, a threshold value is set for the number of relay stages of a relay packet for each destination station, and when a packet is relayed by a packet switching device, if the number of relay stages of the packet becomes a value larger than the threshold value, the packet is relayed as is, but after that it is relayed in a predetermined manner. Packet transmission between the packet originating station and the terminating station is regulated.

[Effect]

Due to the above-mentioned regulations, the present invention prevents continuous use of relay routes that have a low priority or have a large number of relay stages, and therefore are not expected to continue receiving detour packet traffic. This can be prevented and the expansion of network abnormalities can be prevented.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing an example of a packet switching network to which the present invention is applied. In the figure, 2 is a packet transmitting station, 3 is a relay station for packets transmitted from transmitting station 1, and 4 is a relay station for packets transmitted from transmitting station 1. Destination terminating stations 5, 6, 7, and 8 are transmission paths stored in the relay route selection table for packet transmission from relay station 3 to destination terminating station 4, and their usage priority is 5, 6, 7, 8. 8 in order. Also 9, 10, 1
1 and 12 are relay stations connected to transmission lines 5, 6, 7, and 8, respectively. Relay station 9, 10, 11, 12
Although the configuration of the transmission path and relay stations from to the terminating station 4 is not shown, for example, the relay station 9 is directly connected to the terminating station 4, and the relay station 12 is connected to the terminating station after bypassing many relay stations. It can be considered that it is connected to 4. Further, although the route from the originating station 2 to the relay station 3 is not shown, it is assumed that the route from the transmitting station 2 to the relay station 3 is reached via a transmission path selected from among a plurality of transmission paths.

FIG. 3 is a format diagram showing an example of the structure of a relay route selection table, and shows a relay route selection table stored in the relay station 3 and corresponding to the receiving station 4, 13, 14, 15,
16 are storage areas for relay route numbers to be selected in the first, second, third, and fourth priorities, respectively;
Regarding the example shown in FIG. 2, transmission lines 5, 6,
Numbers 7 and 8 are stored respectively. In the relay station 3, a relay route selection table corresponding to all the receiving stations is stored. The same applies to other relay stations.

FIG. 1 is a format diagram showing a relay route selection priority threshold storage area according to the present invention.
For example, is an area in which the relay route selection priority threshold N for the receiving station 4 is stored.

Assume that a packet sent from the originating station 2 and addressed to the terminating station 4 reaches the relay station 3. The relay station 3 includes transmission lines 5, 6, 7, 8 connected to the relay station 3, and relay stations 9, 10, 11, 11 connected to the other ends of these transmission lines.
12, and the relay route selection table (third
(see figure), it is checked whether each relay path is currently usable in order of priority, and the usable relay path with the highest priority is selected. Assuming that the priority of the relay route selected in this way is M, M is compared with the value N of threshold 1 addressed to the receiving station 4 in the relay route selection priority threshold table shown in FIG. M
>N, it is determined that the packet is abnormal, and at the same time the packet is relayed, an abnormality notification packet is sent to the sending station 2 and receiving station 4 of the packet to notify that the relay path priority threshold has been exceeded. send. Source station 2 and destination station 4 that received the abnormality notification packet
After that, packet transmission to the other station is stopped for a predetermined period of time. In this way, it is possible to prevent continuous use of a relay path that has a low priority and is therefore not expected to continue receiving detour packet traffic.

Furthermore, another embodiment will be described with reference to the drawings.
FIG. 5 is a block diagram showing an example of a packet switching network according to this embodiment. In the figure, reference numeral 13 denotes a relay station for packets transmitted from the originating station 2 to the terminating station 4. In FIG. Although the configurations of the respective transmission paths and relay paths from the originating station 2 to the relay station 13 and from the relay station 13 to the destination station 4 are not shown, packets are relayed via multiple transmission paths and relay stations. shall be taken as a thing. FIG. 1 is a format diagram showing a relay stage number threshold value storage area according to the present invention. For example, relay stage number threshold values stored in a relay station 13 and corresponding to all terminating stations are stored, and 14 is a storage area for, for example, a terminating station. This is an area where the relay stage number threshold value X for 4 is stored.

Assume that a packet sent from the originating station 2 and addressed to the terminating station 4 reaches the relay station 13. At this time, if the number of relay stages of the packet is H, then this H is the value X of threshold 14 for destination station 4 in the relay stage number threshold table shown in FIG.
If H>X when compared with Send a packet. After receiving the abnormality notification packet, the originating station 2 and the terminating station 4 stop sending packets to the other station for a predetermined period of time. In this way, it is possible to prevent continuous packet transmission with a large number of relay stages. [Effects of the Invention] As described above, according to the present invention, the relay route selection priority threshold is set corresponding to each receiving station. However, if the priority of the relay route selected when transmitting a relay packet exceeds this threshold, or if a threshold for the number of relay stages is set corresponding to each receiving station and the number of relay stages of the received relay packet exceeds this threshold. After the packet is determined to be abnormal and relayed, packet transmission between the sending and receiving stations is stopped for a predetermined period of time. It is possible to prevent packets from being continuously transmitted to a relay path including a network path, and as a result, anomalies in the network are prevented from expanding.

[Brief explanation of the drawing]

FIG. 1 is a format diagram showing a relay path selection priority threshold storage area according to the present invention, FIG. 2 is a block diagram showing an example of a packet switching network to which this invention is applied, and FIG. 3 is a configuration of a relay path selection table. FIG. 4 is a format diagram showing a relay stage number threshold storage area according to another embodiment of the present invention, and FIG. 5 is a format diagram showing an example of the configuration of a packet switching network to which another embodiment of the present invention is applied. FIG. In the figure, 1 is a relay path selection priority threshold table, 17 is a relay stage number threshold table, 2 is a transmitting station, 3,
9, 10, 11, 12, and 18 are relay stations, 4 is a receiving station, 5, 6, 7, and 8 are transmission paths, and 13, 14, 15, and 16 are relay path selection tables.

Claims (1)

[Scope of Claims] 1. Packet switching in which each packet switching device selects and transmits a suitable relay path corresponding to the destination packet switching device for each received packet, thereby relaying the packet to the destination switching device. In a method for transmitting packets in a network, there is a step in which a relay route selection table is stored in advance in the packet switching equipment, in which the packet transmission trunking routes of each packet switching equipment are stored for each destination along with their transmission priorities. A priority threshold table is stored in advance for each destination to indicate a selection range of relay routes that can be continuously used among the relay routes stored in the relay route selection table for each destination. In the step of storing the packet in the switching device, the packet switching device that received the packet informs the destination packet switching device to which the packet is to be sent of the highest priority relay route available at that time and its priority. A relay path selection step in which the relay path is selected according to the relay path selection table in the packet switching device, and if the priority of the relay path selected in this relay path selection step exceeds the value shown in the priority threshold table above, it is determined to be abnormal. Then, after sending the packet to the relay path, the packet switching device sends an abnormality notification packet to the packet switching device that sent the relay packet, and thereafter makes an abnormality determination to stop packet relay between the sending and receiving switching devices for a predetermined period of time. A method for transmitting packets in a packet switching network, comprising the steps of: 2. In a packet transmission method in a packet switching network in which each packet switching device selects and transmits each received packet to an appropriate relay path corresponding to the destination packet switching device, thereby relaying the packet to the destination switching device. , A relay stage number threshold table is stored in advance in each packet switching device, which stores the relay stage number threshold for each destination, which indicates whether or not a relay packet can be further relayed to the next switching device. Step: When the packet is a relay packet, the packet switching device receiving the packet determines that the packet is abnormal if the number of relay steps so far exceeds the value shown in the relay step number threshold table corresponding to the destination;
Packet switching characterized by comprising the step of: sending an abnormality notification packet to the originating packet switching device of the packet after relaying the packet, and thereafter stopping relaying of packets between the originating and terminating switching devices for a predetermined period of time. A method of transmitting packets in a network.