JPS6376645A - Packet communication system - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] By classifying data output from a terminal device into multiple packet groups that are prioritized according to content, it is possible to A packet communication method that secures the communication path for high-priority data packets even if the data packets are discarded.

[Industrial application field]

The present invention relates to a packet communication system between terminal devices in which data output from the terminal devices is packetized and exchanged for transmission, and particularly relates to securing a communication path for high-priority communication when comparing switching networks.

In a packet-switched network, each packetized data is attached with a destination and transmitted to the other party's terminal device. However, depending on the state of the transmission path in the middle, the data is often transmitted by bypassing the communication network. Compared to circuit-switched networks where routes are fixed, it has superior detour functionality.

However, when a failure occurs in the relay line within the switching network,
When packets that were being transmitted on the faulty line are diverted to the detour line, the traffic on the bypassed transmission line exceeds the permissible traffic on that transmission line, and the communication line is disconnected.

As for the packet communication method, in such a case, it is desirable to avoid completely disconnecting the communication path even if the communication quality is lowered for data packets with higher priority depending on the communication content.

[Conventional technology]

FIG. 3 shows data transmission between terminal devices via a conventional packet switching network. 8 in the figure shows normal communication, and B in the figure
indicates communication during a detour due to a failure.

When a failure occurs at one point 21 to the trunk line 2, communication on the trunk line 2A including the failure point 21 is transferred to the other trunk lines 2B, 2G and the packet switches IA, IB.
.

It is bypassed via the IC.

As a method of detouring, priority is given to each communication path of a relay line or each terminal device.

In other words, terminal device 3 is a device with a high priority, terminal device 4
is a low priority device, communication paths 31 and 32 are high priority communication paths between high priority devices 3Aa and 3B, and between devices 3Ab and 3C, and communication paths 41 and 42 are low priority devices 4Aa. and 4B, and between devices 4Ab and 4C.
When a failure occurs at the location 21, the packets being transmitted are detoured to the detour lines 2B and 2C.

[Problem that the invention seeks to solve]

In conventional packet communication networks, as described above, each communication path or each terminal device is prioritized and detoured, so a failure occurs at one point 21 to the relay line 2, resulting in a failure as shown in B in the figure. When a detour is made to the lines 2B and 2G, if the communication volume of the detoured relay lines 2B and 2C, for example 2B, exceeds the allowable communication volume, the communication path 41 between the low priority devices 4Aa and 4B and the device 4Ab There is a problem in that the communication channel 42 between the terminal and 4C is cut off, and even if the communication channels 41 and 42 contain important data, the communication is completely interrupted.

[Means for solving problems]

The problem mentioned above is that instead of assigning priorities to each communication channel or each terminal device, the data packets to be transmitted are classified into multiple packet groups according to their contents, and priorities are assigned to the classified data packets. This is solved by the present invention which aims to transmit.

Therefore, as shown in FIG. 1, terminal devices 5A, 5B, and 5C are connected to each packet switch IA, which transmits and receives data that has been classified by assigning a plurality of priorities to output data.

It is configured to connect to IB and IC for communication.

31 and 32 are terminal devices 5Aa and 5B, and 5Ab
and 50 are communication channels for transmitting high priority data packets among the output data packets, and 41 and 42 are communication channels for transmitting low priority data packets.

[Effect]

Each terminal device 5A, 5B, 5C transmits and receives data packets with multiple priorities, so when a failure occurs at one location 21 of the relay line 2A, the bypassed relay lines 2B, 2
For example, when the communication amount of 2B of C exceeds the allowable communication amount, the data packets output by the terminal devices 5A, 5B, and 5C will be transferred to the communication path 41 of the lower priority data packets output by the devices 5Aa and 5B. The communication path 32 of the data packet discarded on the relay line 2B and having a high priority is replaced.

In addition, the communication path of the data packet output from the device 5C is as follows:
Both the communication path 32 for high-priority data packets and the communication path 42 for low-priority data packets are maintained up to the switch IB by the trunk line 2C, but in the trunk line 2B between the switch IB and the switch 1, priority is maintained. The communication path 42 for data packets with low priority is discarded, and only the communication path 32 for data packets with high priority output by devices 5Ab and 5C is retained.

In this way, the high priority data packets output from each of the terminal devices 5A, 5B, 5C are maintained as communication paths 31, 32 within the relay lines 2B, 2G without being cut off and mutual communication is maintained.

〔Example〕

FIG. 2 is a block diagram of a packet sending section of an image data terminal device showing the configuration of a packet communication system according to an embodiment of the present invention.

In the figure, 5 is an image data terminal device, 50 is a sending image memory, 50-1 to 50-n are image lines, 51 is a priority packet assembly unit, 52 is a non-priority packet assembly unit, and 53 is a transmission selector. .

The priority packet assembling section 51 is connected to the odd-numbered lines of the image memory 50, assembles priority packets, and passes them to the sending selector 53.

The non-priority packet assembling unit 5z is connected to even-numbered lines of the image memory 50, assembles non-priority packets, and passes them to the sending selector 53.

The transmission selector 53 alternately transmits each packet output from the priority packet assembly section 51 and the non-priority packet assembly section 52.

If the packet communication network is congested and non-priority packets are discarded, only the odd lines of the priority packets will arrive at the receiving unit (not shown) of the other party's terminal device, and the even lines will not arrive. Although this corresponds to a deterioration in the received image quality, communication continues without being disconnected.

〔Effect of the invention〕

As explained above, according to the present invention, even if the packet communication network becomes congested, it is possible to continue many communications even if the quality is low, and it is possible to maintain high reliability in terms of securing communication channels. The effect of being able to construct a network can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram showing the configuration of a packet communication system according to the present invention. FIG. 2 is a block diagram of a packet sending unit of an image data terminal device showing the configuration of a packet communication system according to an embodiment of the present invention. 1 is a block diagram showing the configuration of a conventional packet communication system. In Figures 1, 2, and 3, LA, IB, and IC are packet switches, 28, 2B,
2C is a relay line, 21 is a failure point of the relay line 2A, 3 is a high priority terminal device, 31.32 is a high priority communication path, 4 is a low priority terminal device, 41.42 is a high priority terminal device, 5A, 5B, 5C are terminal devices for transmitting and receiving multiple data with priorities; 5 is an image data terminal device; 50 is an image memory; 51 is a priority packet assembly section; 52 is a non-priority packet assembly section; 53 is the send selector.

Claims (1)

[Claims] The data output from the terminal devices (5Aa, 5Ab) is packetized and transmitted to the exchange (1A, 5C) to the other terminal device (5B, 5C).
1B, 1C), the terminal devices (5Aa, 5Ab) output data to a plurality of prioritized packet groups (31, 32 and 41).
, 42), and the destination terminal device (5B, 5C) can receive only the high-priority data packet group (31, 32) even if the packet switching network is congested. A packet communication method characterized by: