JPH04107035A - Communication control system - Google Patents

Abstract

PURPOSE:To perform appropriate processing in congestion or the like by adding one to the subsequence value of a frame to transmit the frame at the time of retransmission and reporting the occurrence of retransmission to the reception side and using this parameter on the reception side as a means which detects a probability of congestion or the like of a network. CONSTITUTION:At the time of first transmission of an arbitrary frame, the transmission side sets the value of its parameter, namely, a subsequence value 105 to '0' to transmit the frame. If reception confirmation is not received within the predeterminate time of a reception confirmation wait timer after this data or a communication control information frame is transmitted, the transmission side adds one to the parameter value to set this value to the subsequence value 105 at each time of retransmission and performs transmission. The reception side uses a parameter 102 different in value by stages as the means which detects a probability of congestion or the like of the network.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication system in a network for transmitting data and control information.

[Prior Art] In the conventional technology, the retransmission frame that is transmitted when the reception confirmation waiting timer times out is exactly the same as the previously transmitted frame.

[Issue to be Solved by the Invention uj] Retransmission due to timeout of the reception confirmation waiting timer on the transmitting side occurs due to loss of transmission frames in the network or reception confirmation frames from the other station, or significant arrival delays of these frames. (A Ti1
eout-Based Congestion Co
ntrol 5cherte for wind
ow Flow-Cantorolled Net
orks” IEE JOURNAL ON 5ERE
CTED ARE^S IN C0HHUNICAIT
1ONS, VOL, 5AC-4, NO, 7, 0CTOB
ER1986, P1162-1167).

However, in the case of the prior art, on the receiving side, it was not possible to distinguish between frames that arrived in a normal sequence and frames that arrived as a result of retransmission. Therefore, in order for the receiving side to detect an axle that has occurred in the network, the only way to do so is to send a control information frame explicitly notifying the axle to the transmitting side. However, such a method is not preferable because it requires the transmission of an extra control information frame at the time of the axle, and there is also the problem that the protocol processing becomes complicated.

Since there is no effective means for detecting network axles on the receiving side, @light control of the network is mainly performed on the transmitting side.

However, the convergence 1! performed on the transmitting side! 11 II
This is due to unilaterally reducing the number of consecutive data frames transmitted before receiving a reception confirmation frame without the consent of the receiving side, resulting in an unnecessary confirmation delay (from sending a data frame to receiving a reception confirmation). There were some problems, such as delays.

The present invention uses simple protocol processing to eliminate unnecessary
III.An object of the present invention is to provide a communication control method capable of detecting the possibility of a network axle without transferring information frames.

[Measures to solve #M Pf] The communication control method of the present invention is such that if the transmitting side does not receive a reception confirmation within a scheduled period after transmitting a data or communication control information frame, the frame is retransmitted. It is sent with a parameter added to clearly indicate that.

[Operation] A simple protocol process in which a parameter indicating retransmission, for example, a flag, is added to the retransmission frame to be transmitted when the reception confirmation waiting timer on the transmitting side times out, allows the retransmission frame to be sent without transferring unnecessary control information frames. Notify the receiving side of the occurrence of retransmission.

[Example] The present invention will be described below based on an example applied to a connection-oriented network.

FIG. 1 shows an example of the overall configuration of a transmission frame used in this embodiment. A frame with nine frames is l50807
3 (JISX5109) connection-oriented transport protocol specifications for interconnection between open systems.

In the present invention, the subsequence parameter 102 is used in the header variable part of this regular frame. It is a constituent element. Among these, 103 is the parameter code of the subsequence parameter 102,
Set a value that identifies this parameter. 104 is the parameter length of the subsequence parameter 102, and a value of "1" is set. 105 is a subsequence parameter 102
This parameter value (subsequence value) is set to "0" at the first transmission of a frame to which this parameter is added, and after that, the value of the previous transmission is set to "1" for each retransmission.
” is set.

At the first transmission of any data frame, such as a data or communication control information frame, the subsequence value 105 of the subsequence parameter is "o".

When the reception confirmation waiting timer times out and retransmission is performed, the subsequence value is increased by "1" and transmitted.

That is, when the transmitter first transmits any frame,
If this parameter 1 (subsequence value 105) is set to "0" and the data or communication control information frame is sent, the reception confirmation is not received within the scheduled period of the reception confirmation wait timer. , the sender sends “
Transmission is performed by setting a value incremented by 1" in the subsequence value 105. The receiving side uses the parameter 102 whose value increases at each stage as a means of detecting the possibility of a network axle, etc. do.

In this way, when retransmitting, the parameter value of frame 101 is changed to “
A simple process such as incrementing the value by 1" and sending it can notify the receiving side of the occurrence of retransmission, and the receiving side can use this parameter as a means of detecting the possibility of a network axle, etc. This allows for precise treatment of shaft wheels and the like.

In the above embodiment, the value of this parameter is set to "0" at the time of the first transmission of the frame, but this parameter is omitted at the time of the first transmission of the data frame, and the value of this parameter is set to "0" at the time of the first transmission of the data frame. This is substantially equivalent to an implementation in which this parameter is added to the data and sent. In either case, it is possible to know on the receiving side that the received frame has been retransmitted based on the parameter information.

Further, the parameter length of the parameter 102 can be appropriately determined as required, and as a simple method, the parameter 102 can be configured with a flag.

[Effects of the Invention] As described above, according to the present invention, by a simple process of increasing the subsequence value of a frame by 1 and transmitting it at the time of retransmission, it is possible to notify the receiving side of the occurrence of retransmission, As a result, the receiving side can use this parameter as a guide for detecting the possibility of network convergence, etc., and can take appropriate measures for the shaft wheels, etc.

[Brief explanation of the drawing]

FIG. 1 shows an example of the structure of a transmission frame used in the present invention. In the figure, 101 is a frame, 102 is a subsequence parameter, 103 is its parameter code, 104 is a parameter length, and 105 is a subsequence value (parameter value).

Claims (1)

[Claims] 1. Communication characterized in that if the transmitting side does not receive a reception confirmation within a scheduled period after transmitting a data or communication control information frame, the frame is sent with a parameter clearly indicating that it is a retransmission frame. control method.