JPH0364229A - Packet flow control system - Google Patents

Abstract

PURPOSE:To deal with the degradation of transmission quality of a relay line by increasing the standard set value of the transmission timing of a receivable packet within the limit value of a reception confirming timer of each stored terminal when the counted value of transmission errors exceeds the allowable frequency of transmission errors. CONSTITUTION:A link level control function part 7 always monitors the data A3 received and transmitted via the relay line 3 connected to a packet device 1. A transmission error counting function part 8 counts the transmission errors. When the counted value of the transmission errors exceeds the allowable transmission error value, the receivable packet transmission timer values of the receivable packet transmission function parts 111-113 of the stored terminal communication control parts 41-43 are set larger than the standard timer value. Consequently, the flow speeds of data A21-A23 are reduced less than a normal speed and the quantity of the data A3 is suppressed. Thus it is possible to deal with the degradation of transmission quality of the line 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a packet flow control system for a packet switch and a packet multiplexing device (packet device) used for packet-switched data transmission, and particularly to a packet flow control method when the transmission quality of a trunk line deteriorates. Related to packet flow control methods.

[Conventional technology]

Conventionally, in this type of packet flow control method, communication control on trunk lines between packet devices is performed by transmitting a Receive Not Receivable (RNR) monitoring frame at the link level due to a decrease in reception buffer resources. Communication control due to quality deterioration and flow control for each accommodated terminal communicating using trunk lines were not performed.

[Problem to be solved by the invention]

In the conventional packet flow control described above, even when the transmission quality of the central i line has deteriorated and data is difficult to flow due to frequent transmission errors, data from each accommodation terminal of the packet device is sent to the packet device, and the data within the device is RNRN is sent to a terminal only after the reception buffer for each accommodated terminal is filled.
A visual frame is transmitted. For this reason, there is a problem in that not only unevenness due to repeated error retransmissions but also a congestion state due to the buffer full of each accommodated terminal occur, making it difficult for -layer data to flow. Further, even if the transmission quality of the trunk line is restored, there is a problem in that the state of uneven distribution continues due to the concentration of data transmission from each accommodated terminal, and the state in which it is difficult for data to flow becomes prolonged.

[Means to solve the problem]

The packet flow control method of the present invention includes a transmission error detection and counting means that detects the occurrence of a transmission error by a frame check sequence of the link level control function (HDLC procedure) of the trunk line and adds up the number of times the error occurs, and a transmission error tolerance storage means for storing in advance the transmission error tolerance number; a comparison means for comparing the transmission error count added by the transmission error detection counting means with the transmission error tolerance number in the storage means; In order to limit data transmission from accommodated terminals communicating using trunk lines when the transmission error count exceeds the above-mentioned transmission error tolerance value, the packet level control function controls the number of receivable packets for each accommodated terminal. and means for lengthening the standard setting value of the transmission timing within the limit value of the reception confirmation timer of each accommodated terminal.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 (A) showing an embodiment of the present invention,
Referring to (B), the link level control function unit 7 of the trunk line communication control unit 5 constantly monitors the data A3 transmitted and received on the trunk line 3 connected to the packet device (packet switch or packet multiplexer) l. When the transmission error detection and counting function section 8 detects a transmission error using the frame check sequence (Fe2), it counts the number of transmission error occurrences N. When the number of times N of transmission errors occurs becomes larger than the number of permissible transmission errors A registered in advance in the permissible transmission error number value memory table 9, it is determined that the transmission quality of this trunk line 3 has deteriorated, and the relay Accommodation terminals 21 and 22 that communicate using line 3
．． Ready to receive (RR) packet transmission function units 111, 112, 11 in packet level control function units 61, 82, 63 existing in accommodation terminal communication control units 41, 42, 43 to 23
The ready-to-receive (RR) packet transmission timer value T of No. 3 is set to be larger than the standard timer value T0 within a range smaller than the limit value T1 of the reception confirmation timer of each accommodated terminal. As a result, data A21. A22. The data flow speed of A23 is lower than normal, and the amount of data A3 can be suppressed.

〔Effect of the invention〕

As explained above, according to the present invention, when a drop in transmission quality of a trunk line occurs, communication to the trunk line with degraded quality is stopped before the transmission/reception buffers of the trunk line communication control unit and the accommodated terminal communication control unit are filled. By restricting the transmission, normal transmission and reception can be performed as soon as the transmission quality of the trunk line is restored.

[Brief explanation of drawings]

l... Packet device, 21, 22, 23...
... Accommodation terminal, 3 ... Relay line, 41, 42,
43... Accommodating terminal communication control unit, 5...
Trunk line communication control unit, 61.62.63... Packet level control function unit, 7... Link level control function unit, 8... Transmission error detection counting function unit, 9
...Transmission error tolerance value memory table, 10
...Comparison function section, 111, 112゜113...
...Receivable packet transmission function section, A21°A22.
A23. A3...Data.

Claims (1)

[Claims] Transmission error detection and counting means that detects the occurrence of transmission errors according to the frame inspection sequence of the link level control function of the trunk line and adds up the number of error occurrences, and a transmission error tolerance value storage that stores in advance the number of transmission errors that are allowed to occur in the trunk line. means for comparing the transmission error count added by the transmission error detection and counting means with the transmission error tolerance number in the storage means; In order to restrict data transmission from accommodated terminals that communicate using trunk lines in such cases, the packet level control function sets the timing for sending receivable packets to each accommodated terminal using the reception confirmation timer of each accommodated terminal. and means for lengthening a standard setting value within a limit value.