JP2604494B2 - Token ring LAN flow control method - Google Patents

Description

The present invention relates to a token ring LAN flow control system.

[Conventional technology]

In a token-passing type loop network system that includes a plurality of loop interface devices in a transmission path, a loop that acquires a token circulating on the transmission path in order to control the flow of data on the transmission path is conventionally used. The interface device is configured to be able to transmit data to a transmission path regardless of the destination of the transmission if a transmission request is made.

[Problems to be solved by the invention]

In the conventional token ring LAN flow control method described above, since the transmission capacity of a transmission line forming a loop is generally larger than the data processing capacity of one loop interface device, when data transfer to one loop interface device is concentrated, Since a large amount of data exceeding the processing capacity of the loop interface device is received one after another, there is a disadvantage that data cannot be received due to a buffer overflow or a part of the data is missed.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and eliminate the possibility of unreceivable or partial data loss of a token ring LAN
It is to provide a flow control method.

[Means for solving the problem]

The token ring LAN flow control method according to the present invention is such that in the token ring LAN flow control method in a token-passing type loop network system configured to include a plurality of loop interface devices in a transmission path, the transmission path circulates around the transmission path. A plurality of address fields are provided in the token, and in each of the loop interface devices, when a buffer in the device is monitored, and when a predetermined first reference value is divided, its own address is written in the address field of the token. An incoming call suppressing means for erasing its own address which has been previously written when exceeding a predetermined second reference value, and comparing a transmission destination address with an address of an address field in the token when acquiring a token for transmission, If there is a matching address, suspend transmission It is constituted by a transmission suppression means for releasing the acquired token.

〔Example〕

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

FIG. 1 is a block diagram of an embodiment of a loop interface device used in the present invention, and FIG. 2 is a frame configuration diagram of an embodiment of a token used in the present invention.

The loop interface device shown in FIG.
, A reception processing unit 3 for processing received data addressed to the own station, a transmission processing unit 4 for processing transmitted data from the own station, and a token circulating around the transmission path 1. A token extracting unit 5, a buffer managing unit 6 for monitoring the free space of the buffer in the receiving processing unit 3, and an address field operating unit 7 for changing the contents of the address field in the token obtained by the instruction from the buffer managing unit 6.
An address field search / comparison unit 8 that searches the address field in the token acquired for transmission and compares it with the destination address, and suspends transmission when the destination address exists in the address field in the token. It comprises a transmission suppressing unit 9 and a token sending unit 10 for returning the acquired token to the transmission line 1 for transmission.

Among the above-described units, the token extraction unit 5, the buffer management unit 6, the address field operation unit 7, and the token transmission unit 10
Constitutes an incoming call suppressing means for preventing data destined for the own station from being transferred more concentratedly than the reception processing capacity, and includes a token extracting unit 5, an address field search comparing unit 8, a transmission suppressing unit 9, and a token sending unit. Numeral 10 constitutes a transmission suppressing means for temporarily suspending transmission when the partner station to be transmitted exceeds the processing capacity.

 Hereinafter, the operation of FIG. 1 will be described.

The buffer management unit 6 constantly monitors the use state of the buffer in the reception processing unit 3, and when the free space of the buffer decreases and becomes less than a predetermined value (first reference value), the buffer management unit 6 checks this. Upon detection, it instructs the token extraction unit 5 to acquire the token and pass it to the address field operation unit 7. As shown in FIG. 2, a plurality of address fields AF are provided in the token circling the transmission line 1. Address field operation unit 7 to which the token has been passed
Adds its own address to an unrecorded address field in the token and sends it out to the transmission line 1 via the token sending unit 10.

Thereafter, when the processing in the reception processing unit 3 proceeds and it is detected that the free buffer area of the buffer management unit 6 has become equal to or larger than a predetermined value (second reference value), the token extraction unit 5 acquires the token again. Then, the address field operation unit 7 erases the own address previously added to the address field in the token and sends it to the transmission line 1.

On the other hand, when data is to be transmitted, the token extracting unit 5 obtains the circulating token and obtains the address field search comparing unit 8 according to an instruction from the transmission processing unit 4.
Pass to. The address field search / comparison unit 8 searches the address field of the received token, and if there is no destination address to be transmitted from its own station,
The data frame prepared from the transmission processing unit 4 is transmitted to the transmission line 1
After that, the token is transmitted to the transmission path 1 via the token transmitting unit 10. When the address of the transmission destination is added to the address field in the token, the transmission suppression unit 9 is controlled to suspend transmission, and the token is transmitted to the transmission line 1.
Return to.

As a result, the interface device in which the reception is concentrated and the free space in the buffer is reduced, the interface device that writes the own address in the address field in the token and registers that it is in the reception suppression state, and the interface device that intends to transmit, The address field of the acquired token is checked, and the transmission is performed after confirming that the interface device of the transmission destination is not in the reception suppression state.

FIG. 3 is a configuration diagram showing an example of a LAN system to which the present invention is applied. Four interface devices 11 to 14 are connected to a regular transmission line 1 and a spare transmission line 1a. Each of the interface devices 11 to 14 may be provided with two sets of circuits each having the configuration shown in FIG. 1, but a part of them may be used for both normal and standby use.

〔The invention's effect〕

As described in detail above, in the present invention, each loop interface device has a buffer management unit, operates the address field in the token before the buffer overflows to suppress reception, and when transmitting, the The address field is checked to make sure that the destination loop interface device is not in the reception suppression state, and then transmitted, so even if reception traffic concentrates on one interface device, data is received due to buffer overflow. It is possible to prevent the data from being missed or a part of the data from being missed, and to prevent the occurrence of troubles such as data retransmission or retransmission.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of a loop interface device used in the present invention, FIG. 2 is a frame configuration diagram of an embodiment of a token used in the present invention, and FIG. 1 is a configuration diagram of an example of a LAN system to which the present invention is applied. 1, 1a transmission line 2, relay transfer processing unit 3, reception processing unit 4, transmission processing unit 5, token extraction unit 6,
... Buffer management unit, 7 ... Address field operation unit,
8 ... address field search comparing unit, 9 ... transmission suppressing unit, 10 ... token sending unit, 11-14 ... loop interface device.

Claims (1)

(57) [Claims] 1. A token ring LA in a token-passing type loop network system including a plurality of loop interface devices in a transmission path.
In the N-flow control system, when a plurality of address fields are provided in a token that circulates the transmission line, when each loop interface device monitors a free space in a buffer in its own device and divides a predetermined first reference value. Write your address in the address field of the token,
An incoming call suppressing means for erasing its own address which has been written before exceeding a predetermined second reference value, and comparing a destination address with an address of an address field in the token when a token is acquired for transmission. And a transmission suppressing means for releasing the acquired token by suspending the transmission when there is a matched address, and a token ring LAN flow control method.