JPH04940A - Traffic control system - Google Patents

Abstract

PURPOSE:To adjust the data transmission/reception volume by always monitoring the idle slot rate on a transmission line by each terminal station and automatically adjusting the interval of idle slots to be used in accordance with the result. CONSTITUTION:The central processing circuit 13 of respective terminal stations 1 to 4 performs the operation as follows; each of terminal stations 1 to 4 always monitors a transmission line 5 to measure an idle slot rate M by the number of idle slots passing for a certain time, and the interval W of idle slots to be used is determined in accordance with the idle slot rate M when a transmission data queue 14 has transmission data, and one is subtracted from the value of the interval W at the time of receiving an idle slot, and the busy bit P of the reception idle slot is set to 1 and the data of the station itself is transmitted when the subtraction result is 0. Thus, each data is independently operated in such direction that the traffic is equalized among respective transmission lines 5 in accordance with a ratio corresponding to the traffic condition of the transmission line 5. That is, the data transmission volume of each of terminal stations 1 to 4 is adjusted in accordance with the increase or the reduction of the traffic of the transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a traffic control method in a slotted ring data transmission system.

[Conventional technology]

A slotted ring data transmission system transmits information between terminal stations connected via a loop-shaped transmission line. In such a slotted ring type data transmission system, when an empty slot is received, it can be used unconditionally or according to a fixed value of allocated bandwidth.

[Problem to be solved by the invention]

The slotted ring data transmission system described above has a drawback in that it is not possible to adjust the data transmission amount of each terminal station to an optimal value in accordance with increases and decreases in traffic on the transmission path.

SUMMARY OF THE INVENTION An object of the present invention is to provide a traffic control method that can eliminate such drawbacks and adjust the amount of data transmitted and received in a slotted ring data transmission system.

[Means for Solving the Problems] The present invention provides a slotted ring in which data is exchanged between a plurality of terminal stations connected by a loop-shaped transmission path using fixed-length slots that flow continuously on a transmission path. The traffic control method for the data transmission system is characterized in that each terminal station constantly monitors the empty slot ratio on the transmission path, and automatically adjusts how many empty slots to use according to the results of this monitoring.

The present invention also provides traffic control in a slotted ring data transmission system in which data is exchanged between a plurality of terminal stations connected by a loop-shaped transmission path using fixed-length slots that flow continuously on the transmission path. In this method, each terminal station is equipped with a reception control circuit that controls reception, a transmission control circuit that controls transmission, and a transmission data queue that holds transmission data, and receives slots received from the transmission path. The feature is that the transmission control circuit sends the data held in the transmission queue to the transmission line as a data frame when the circuit determines that the data can be transmitted.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the configuration of a data transmission system to which the present invention can be applied. In FIG. 1, terminal stations 1 to 4 have the function of transmitting and receiving data. Further, the terminal stations 1 to 4 are connected in a ring shape by a transmission line 5.

Each terminal station has a configuration as shown in FIG. In FIG. 2, 5 is the transmission line shown in FIG.
11 is a reception control circuit, 15 is a transmission control circuit, 13 is a central processing circuit, and 12 is a reception data queue 14 is a transmission data queue. The slot received from the transmission path 5 is determined by the reception control circuit 11, and if it is determined that data can be transmitted, the transmission control circuit 15 sends the data held in the transmission data queue 14 to the transmission path 5 as a data frame. Even if data transmission is possible, the transmission data queue 14
If is empty, the empty slot is passed through. The central processing circuit 13 adjusts the operation between each circuit in the device.

In such a data transmission system, an example format of a frame for transmitting data on each transmission path is shown in FIG. In FIG. 3, F indicates a synchronization pattern, DA indicates a destination station address, and SA indicates a source terminal station address. P is a used bit; when P=1, it indicates that the slot is in use (in-use slot), and when P=0, it indicates that the slot is unused (empty slot). Furthermore, ■ is a data section, which is used to transmit data between terminal stations.

An empty slot means that the terminal station that receives it can transmit data, and when a terminal station that has transmission data receives this slot, it inserts its own terminal station's transmission data into one part with P = 1. Assume that data can be transmitted to the terminal station indicated by the DA.

In addition, after transmitting the data frame, in order to give the next terminal station the transmission right, an empty slot is generated with P=O,
It shall be sent to the transmission line. A data frame received at the destination station is removed from the transmission path at the receiving end station or the transmitting end station.

Such a data transmission system operates according to an algorithm as shown in FIG. FIG. 4 is an example of an algorithm of a program to be incorporated into the central processing circuit to realize the functions of the present invention.

In a normal data transmission device, data is held in the transmission data queue 14 shown in FIG. 2, and when an empty slot is received, it can be used unconditionally or at a fixed rate. However, in the method of the present invention, the ratio of empty slots to be used can be automatically adjusted by an algorithm as shown in FIG.

The procedure will be explained below.

First, each terminal station constantly monitors the transmission path 5.
The empty slot rate M is measured based on the number of empty slots that pass in a certain period of time (step S1). Further, it is determined whether there is any transmission data in the transmission data queue 14 of FIG. 2 (step 32), and if there is no transmission data, the process returns to step S1. When there is transmission data in step S2, an interval W for using empty slots is determined from the empty slot rate M using a formula determined as a system default value (step S3). The interval W is an integer of "1" or more, and the calculation formula is a system parameter that is optimal for the operation of each system.

When an empty slot is received, the value of the interval W is set to "1".
(step S4). It is determined whether the value of the interval W is "0" (step S5), and the value of the interval W is "0".
0'', the process returns to step S4. When the value of the interval W is "0" in step S5, P of the reception empty slot shown in FIG. 3 is set to "1" and the own station data is transmitted (step S6). That is, when transmission data is generated in the transmission data queue of the own station, the own station data is transmitted using the Wth empty slot that has arrived since then. This will be repeated from here on.

Through the operations described above, each piece of data independently operates in a direction that equalizes the traffic on the transmission line at a ratio according to the congestion of the transmission line.

[Effects of the Invention] As explained above, the present invention has a function in which each terminal station constantly monitors the empty slot rate on the transmission path and automatically adjusts how many empty slots to use according to the result. This has the effect of optimizing the traffic on the transmission path and the throughput of each terminal station.

[Brief explanation of drawings]

1 is a diagram showing an example of the configuration of a data transmission system to which the present invention is applied; FIG. 2 is a diagram showing an example of the internal configuration of a terminal device of the data transmission system of FIG. 1; FIG. FIG. 4 is a diagram showing an example of a frame format for transmitting data on the transmission path of the data transmission system shown in FIG. 1. FIG. FIG. 3 is a diagram showing an example of an algorithm of a program to be incorporated into a circuit. 1 to 4...Terminal station 5...Transmission line diagram

Claims (2)

[Claims] (1) In a traffic control method for a slotted ring data transmission system in which data is exchanged between multiple terminal stations connected by a loop-shaped transmission path using fixed-length slots that flow continuously on the transmission path, A traffic control method in which each terminal station constantly monitors the empty slot rate on the transmission path, and automatically adjusts how many empty slots to use according to the results of this monitoring. (2) In a traffic control method for a slotted ring data transmission system in which data is exchanged between multiple terminal stations connected by a loop-shaped transmission path using fixed-length slots that flow continuously on the transmission path, Each terminal station is equipped with a reception control circuit that controls reception, a transmission control circuit that controls transmission, and a transmission data queue that holds transmission data, and the reception control circuit determines the slot received from the transmission path. A traffic control method characterized in that, when it is determined that the data can be transmitted, the transmission control circuit sends the data held in the transmission queue to the transmission path as a data frame.