JP2785608B2 - Congestion control method of packet switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a congestion control system for a packet switch, and more particularly to a congestion control system for a packet switch for controlling congestion when a buffer usage rate of a communication control module exceeds a predetermined congestion reference value. .

[0002]

2. Description of the Related Art Conventionally, in this type of packet switch, 1
The two communication control modules stop transmitting data packets when receiving a reception disable signal from a terminal under the communication control module, store data packets received from the communication control module of the communication partner in their own queues, and as a result, detect congestion. In this case, even after detecting congestion, the communication control module stores the data packet in its own queue when receiving a data packet from the communication control module of the communication partner, and stores the data in its own queue when the communication control module receives the reception enable signal from the terminal. The congestion control method of transmitting congestion by transmitting the data packet stored in the terminal to the terminal.

FIG. 3 is a sequence diagram showing an example of the operation of a conventional packet switch. Communication control module 102
Stops receiving the unreceivable signal 301 from the subordinate terminal 107, stops the transmission of the data packet 302, and returns the data packet 3 received from the communication control module 101 of the communication partner.
02 is stored in its own queue 310. As a result, when congestion is detected, the communication control module 102 stores the data packet in its own queue 310 when receiving a data packet from the communication control module 101 of the communication partner even after detecting the congestion, and the communication control module 102 Terminal 10
7 when receiving the reception enable signal 303 from the queue 3
The data packet 302 stored in the terminal 107
To release the congestion.

[0004]

In this conventional packet switch, when one communication control module receives a non-reception signal from a subordinate terminal, transmission of data packets is stopped and data received from the communication control module of the communication partner is stopped. The packet is stored in its own queue, and when congestion is detected as a result, the communication control module stores the data packet in its own queue when receiving a data packet from the communication control module of the communication partner even after detecting congestion. Therefore, even if the buffer usage rate becomes large and the data packet is transmitted to the subordinate terminal after receiving the reception enable signal from the subordinate terminal, it takes time for the buffer usage rate to fall below the congestion release reference value. As a result, there is a problem that efficient congestion cancellation cannot be performed.

[0005]

A congestion control system for a packet switch according to the present invention comprises a plurality of communication control modules connected by a single bus, and each of the communication control modules always has its own communication control module. And the terminals under the respective communication control modules are determined in advance for the priority or non-priority of packet transmission for each terminal, and the respective communication control modules are used by the respective communication control modules. A packet switch that determines that a buffer is more congested when the usage rate of the buffer exceeds a predetermined congestion reference value, and that determines that the congestion is released when the usage rate of the buffer falls below a predetermined congestion release reference value. A congestion control method, wherein the communication control module is configured to notify a buffer usage rate from the left communication control module at a fixed cycle. Upon receiving the notification signal, the usage rate of the buffer of the communication control module on the left side is constantly monitored. When the one communication control module receives the reception impossible signal from the terminal under the control, the one communication control module stops transmitting the data packet and stops communication with the communication partner. The supervisory communication control module, which stores the data packets received from the communication control module in its own queue, and monitors the buffer utilization as a result, detects the congestion of the left communication control module, The control module sends a save request signal to the congested congestion communication control module on the left side to notify that the data packet received by the congestion communication control module is temporarily stored, and receives the save request signal. The congestion communication control module then transmits the data packet received from the communication control module of the communication partner. The data packet transmitted from the priority terminal is stored in its own queue, but the data packet transmitted from the non-priority terminal is once transmitted to the supervisory communication control module to transmit the data packet to the supervisory communication control module. When the congestion communication control module receives a reception enable signal from a terminal, the congestion communication control module transmits the data packet stored in the queue to the terminal to the terminal. When the usage rate of the buffer of the congestion communication control module is lower than the congestion release reference value by the buffer notification signal received from the module, the congestion communication control module determines that congestion has been released and enters its own queue. The stored data packet is sent to the congestion communication control module. It is characterized by being returned.

[0006]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a packet switch showing one embodiment of the present invention, and FIG. 2 is a sequence diagram showing an operation of the packet switch of this embodiment.

First, the configuration of the packet switch of the present embodiment will be described with reference to FIG. In FIG. 1, the packet switch 105 includes communication control modules 101, 102,
103 is connected to one bus 104, and each communication control module 101, 102, 103 has a non-priority packet terminal (hereinafter simply non-priority terminal) 106, 108, 110
And priority packet terminals (hereinafter simply referred to as priority terminals) 107 and 10
9, 111 are accommodated respectively.

Next, the operation of this embodiment will be described with reference to FIGS. Communication control module 10
1, 102, and 103 receive a buffer notification signal 201 (in the direction of arrow 120 in FIG. 1) for notifying the buffer usage rate from the left communication control module at a fixed period, and constantly adjust the buffer usage rate of the left communication control module. Monitor.

When one communication control module 102 receives a non-reception signal 202 from a subordinate non-priority terminal 108, it stops transmitting the data packet 203, and the data packet 20 received from the communication control module 101 of the communication partner.
3 is stored in its own queue 220, and as a result, when the communication control module 103 (hereinafter referred to as “monitoring communication control module”) monitoring the usage rate of the buffer detects the congestion of the communication control module 102 on the left side, The supervisory communication control module 103 sends a message to the congested communication control module 102
The evacuation request signal 204 is transmitted to notify that the congestion communication control module 102 temporarily stores the data packet received from the communication control module 101 of the communication partner in the monitoring control module 103.

The congestion communication control module 102 having received the evacuation request signal 204 stores the data packet 203 transmitted from the priority terminal 107 among the data packets 203 received from the communication control module 101 of the other party in its own queue 220. But the non-priority terminal 1
The data packet 203 transmitted from the data packet 203 is transmitted to the monitoring communication control module 103 once, and the monitoring communication control module 103 transmits the received data packet 203 to the monitoring communication control module 103.
Is stored in its own queue 221.

When the congestion communication control module 102 receives the reception enable signal 205 from the subordinate non-priority terminal 108, it transmits the data packet 203 stored in its own queue 220 to the subordinate non-priority terminal 108.

The monitoring communication control module 103 receives the buffer notification signal 2 received from the congestion communication control module 102.
01, when the buffer usage rate of the congestion communication control module 102 is lower than the congestion release reference value, the congestion communication control module 102 determines that the congestion is released and stores the data packet 203 stored in its own queue 221.
Is returned to the congestion communication control module 102.

The communication control module 102 transmits the data packet 203 returned from the monitoring communication control module 103.
Is stored in its own queue, and the subordinate non-priority terminal 108
To the data packet 203.

[0014]

As described above, according to the present invention, one communication control module stops transmission of a data packet to a terminal when receiving a reception impossible signal from a subordinate terminal, and receives the data packet from the communication control module of the communication partner. Data packets are stored in their own queues. As a result, when the monitoring communication control module detects congestion of the communication control module that is monitoring the buffer usage, the congestion communication control module evacuates from the monitoring communication control module. After receiving the request signal, the data packet transmitted from the non-priority terminal among the data packets received from the communication control module of the communication partner is stored in the queue of the supervisory communication control module instead of being stored in its own queue. Has reduced the number of data packets stored in its own queue,
As a result, the use rate of the buffer of the congestion communication control module is reduced, so that the congestion of the communication control module can be efficiently and quickly released.

[Brief description of the drawings]

FIG. 1 is a block diagram of a packet switch showing one embodiment of the present invention.

FIG. 2 is a sequence diagram showing an operation of the packet switch of the embodiment.

FIG. 3 is a sequence diagram showing an example of the operation of a conventional packet switch.

[Explanation of symbols]

101, 102, 103 Communication control module 104 Bus 105 Packet switch 106, 108, 110 Non-priority packet terminal (non-priority terminal) 107, 109, 111 Priority packet terminal (priority terminal) 120 Buffer notification signal transmission direction 201 Buffer notification signal 202 , 301 Reception disabled signal 203, 302 Data packet 204 Evacuation request signal 205, 303 Reception enabled signal 220, 310 Queue of communication control module 221 Queue of communication control module 103

Claims (1)

(57) [Claims] 1. A communication control module comprising: a plurality of communication control modules connected by a single bus; each of the communication control modules always notifies a right communication control module of its own buffer usage rate; Subordinate terminals are determined in advance for the priority and non-priority of packet transmission for each terminal, and each of the communication control modules is configured to use a case where the usage rate of the buffer used by each communication control module exceeds a predetermined congestion reference value. It is a congestion control method of a packet switch, which judges that the congestion is congested, and judges that the buffer is below congestion release when the usage rate of the buffer falls below a predetermined congestion release reference value. Receives the buffer notification signal for notifying the usage rate of the buffer from the left communication control module, and constantly buffers the buffer of the left communication control module. When one of the communication control modules receives a reception impossible signal from the subordinate terminal, the one communication control module stops transmitting the data packet and places the data packet received from the communication control module of the communication partner in its own queue. When a communication control module (hereinafter referred to as a monitoring communication control module) monitoring the usage rate of the buffer detects congestion of the communication control module on the left side, the monitoring communication control module stores the data on the left side. A congestion communication control module (hereinafter referred to as a congestion communication control module) transmits an evacuation request signal to notify that the data packet received by the congestion communication control module is temporarily stored, and transmits the evacuation request signal to the congestion communication control module. The received congestion communication control module then transmits the data packet received from the communication control module of the communication partner. Among data packets, data packets transmitted from a priority terminal are stored in its own queue, but data packets transmitted from a non-priority terminal are temporarily transmitted to the supervisory communication control module to transmit the data packet to the supervisory communication module. Control module, when the congestion communication control module receives a reception enable signal from a terminal, sends the data packet stored in its own queue to the terminal, the monitoring communication control module When the usage rate of the buffer of the congestion communication control module is lower than the congestion release reference value by the buffer notification signal received from the congestion communication control module, the congestion communication control module determines that congestion is released and determines its own The data packet stored in the queue is transferred to the congestion communication control mode. Congestion control method for a packet switching system, characterized by sending back to Yuru.