JPH08186600A - Relay congestion detecting method in store and forward switching network - Google Patents

Abstract

PURPOSE: To reduce burden on the processing of congestion detection notice of a tandem switch by judging congestion by measuring the reception line working ratio of or reception data quantity on a relay line by an incoming call side exchange. CONSTITUTION: When communication is performed via the tandem switches 21, 22 by setting a logic channel between exchanges 20 and 23, the exchange 23 measures the reception line working ratio or data quantity from the tandem switch 22 by, for example, a reception buffer working ratio. When the line working ratio or data quantity exceeds a threshold value in fixed time, it is judged that the congestion occurs in the relay line 42 of the tandem switch 22, and it is informed to the exchange 20. In this way, congestion control processing such as the congestion detection notice, etc., on a tandem switch 22 side is reduced, and the congestion of the tandem switch is prevented from being further propagated by the congestion processing when the congestion occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay congestion detection method in a switching network including a plurality of terminals and a switching system, particularly in a storage switching network for packet communication.

[0002]

2. Description of the Related Art FIG. 1 shows an example of the structure of a storage switching network. Ten,
Reference numeral 11 is a terminal, 20, 21, 22, and 23 are exchanges, 30 and 31 are subscriber lines connecting the terminals and the exchanges, and 40, 41, and 42 are relay lines connecting the exchanges. However, this figure shows a part of the storage and switching network, and in reality, a large number of lines and exchanges are present to form the network. In such a configuration of the switching network, the conventional congestion detection method is that the transit exchange detects a congestion state, and the state is congested to the originating exchange or the surrounding exchange or all exchanges connected to the exchange via the transit line. I was giving notice.

For example, a normal congestion is detected by observing the CPU utilization rate of the exchange (in this case, observing the no-load time per unit time, and determining that the congestion occurs when the reference time exceeds a certain time) or the buffer utilization rate. (In this case, the number of buffers used per unit time is observed and congestion occurs when the reference value is exceeded for a certain period of time or more). The congestion state is notified to the exchange by the congestion notification packet.

Upon receipt of the congestion notification packet from the transit exchange, the originating and terminating exchange displays the congestion in the routing table and regulates packet transmission by call processing.
In this case, regarding the selection of the notification destination, for example, when notifying the originating and terminating exchanges, the set of exchanges that are using the line is stored for each line, and when notifying to the surrounding exchanges, the line Remember the correspondence with the destination exchange,
When notifying all the exchanges, it is realized by a method of storing all addresses of all the exchanges.

[0005]

In the conventional congestion detection notification method as described above, each exchange independently detects the congestion, and when congestion is detected, the congestion notification to other exchanges is performed by one unit. There is a problem that the notification processing load is heavy because it needs to be concentrated, and that such congestion notification itself increases the line load and causes new congestion. An object of the present invention is to provide a relay congestion detection method that solves such problems and reduces the processing load of congestion detection notification of a transit exchange.

[0006]

According to the present invention, in order to solve such a problem, a reception line utilization rate or a reception data amount of a relay line connecting exchanges of a switching network is measured,
Congestion is determined when the usage rate or the amount of data for a certain period of time exceeds a threshold value. As a result, it is possible to estimate and detect the congestion of the sending side exchange even without notification of the congestion from the sending side exchange of the line. According to the method of the present invention, the congestion detection notification, which has been conventionally performed by the transit exchange, can be performed between the originating and terminating exchanges.

[0007]

According to the present invention, it is possible to reduce conventional congestion control processing such as congestion detection notification on the side of the transit exchange, and prevent further propagation of the congestion of the transit exchange during the congestion processing when congestion occurs.

[0008]

EXAMPLE An example of the present invention will be described below with reference to FIG. As will be shown below, the present invention is realized by the internal control of the exchange, so that no addition or modification to the hardware of the exchange is necessary.

According to the present invention, the congestion state in the originating and terminating exchanges is detected by observing the line utilization rate or the data amount for each trunk line between the trunk exchanges. Various methods can be used to calculate the line usage rate or data amount, such as the method of calculating the usage rate of the receive buffer provided for each switch in correspondence with the line. The effect of the invention does not change.

In the figure, a case where a logical channel is set between the exchanges 20 and 23 will be described.
The exchanges 20 and 23 communicate with each other via the relay exchanges 21 and 22. The exchange 23 is connected via the trunk line of the exchange 22.
Data is received from 20. At this time, the line utilization rate or data amount from the exchange 22 is observed, for example, by the receive buffer utilization rate described above, and whether the line utilization rate or data amount exceeds a certain value. If it exceeds, it is determined that congestion has occurred in the relay line of the exchange 22 and the exchange 20
To notify.

There is a method of detecting the congestion state, for example, when the line usage rate or the data amount exceeds a certain fixed value, or when the state in which the line usage rate or the data amount exceeds the certain fixed value continues for a certain period of time. Any method may be used. Further, the congestion state notification may be performed by sending out a congestion notification packet (CONG packet) or the like that is generally used for the congestion state notification.

The exchange 20 that has received the congestion notification packet or
23 sets an indication of congestion in the routing table for the exchange and restricts packets to the exchange by call processing. When the congestion state is released, the congestion release notification packet (FREE packet) is sent to release the restriction. However, except that these procedures are also performed by the originating and terminating exchanges, the congestion caused by the conventional transit exchange is It can be realized by the same control procedure as the release method.

[0013]

As described above, the relay line receiving unit constantly observes the line utilization rate or the data amount at regular time intervals and performs the congestion determination by the threshold value determination, thereby performing the relay line transmission side processing. It enables mitigation and avoidance of congestion propagation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a storage exchange network.

[Explanation of symbols]

 10, 11 Terminals 20-23 Exchanges 30, 31 Subscriber lines connecting subscribers and exchanges 40-42 Relay lines connecting exchanges

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidenori Takahashi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. The reception line utilization rate or the reception data amount of a relay line connecting between exchanges of a switching network is measured, and when the utilization rate or the data amount during a certain time exceeds a threshold value, it is judged as congestion. A relay congestion detection method in a store-and-forward network, characterized by the above.