JP2001326663A - Flow control system by token passing and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow control system by token passing that copes with even a load fluctuation of a receiver side computer, without making the function of the computer complicated. SOLUTION: A computer 1 transmits a set of a busy token and data addressed to a computer 3 to a token ring 4. When the computer 3 has no margin for reception in itself, the computer 3 relays the set. The computer 1 also relays the set. When the computer 3 can afford to receive the set, the computer 3 receives the data of the set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transfer method using token ring, and more particularly, to a flow control method using token passing.

[0002]

2. Description of the Related Art As shown in FIG.
Are connected by a loop transmission path (token ring) 4. At this time, in the transmission flow control for data transmission between the computers, as shown in FIG. 2, the flow control information is added to the acknowledgment 24 according to the load state of the data receiving side 22 to notify the transmission source computer 21. By adopting this method, traffic congestion and the like of transmission data are eliminated. That is, generally, when data is transmitted from the computer 21 to the computer 22 by the token passing method,
As shown in FIG. 2, data is transmitted from the transmission source computer 21 to the reception side computer 22. In response to this, the reception side computer 22 transmits a response signal to the transmission side computer 21.
Return to. At this time, the response signal includes information on the amount of data that can be received next by the data receiving computer 22 or load information such as a delay time until the next data is transmitted. By receiving this load information, the transmission source computer 1 can transmit the data by adjusting the data amount or the delay time at the time of the next transmission.

[0003]

However, the conventional method has the following problems.

A first problem is that load status information of a receiving computer is received as a response signal. Therefore, the transmission source computer cannot acquire the load state information of the receiving computer unless it transmits the first data and receives the response of the receiving computer. Also, when the receiving computer is communicating with a different computer, a situation may occur in which the load state information received immediately before does not match the current state. Therefore, a situation in which the transmitting computer does not have enough time to receive the data to be transmitted to the receiving computer easily occurs, and a transmission error occurs.

[0005] To solve this problem, the prior art uses a LAN
By adding the load information of each computer connected to the free token to the free token, transmission efficiency is improved and transmission errors are avoided, but the load token of all computers exists in the free token immediately after data transmission. Therefore, there is a possibility that the source computer does not include the load information of the receiving computer when the free token is obtained. Further, when many computers are connected to the LAN, there is a problem that the amount of data added to the free token increases.

The second problem is that, as described in the first problem, the transmission error due to the load state of the receiving computer cannot be completely avoided in the method according to the prior art. It is complicated.

[0007] The reason is that it is necessary to add a function of acquiring load state information of each computer from a free token. In storing the load state information, it is necessary to store the states of all the computers constituting the LAN. If you have a lot of computers,
Since such resources are required, the size of the apparatus is increased and the complexity is increased in order to grasp all the states. In addition, if the number that can be stored with a certain value is limited, there is a high possibility that the number is limited to the connection configuration, which is a serious problem in practicality.

For the reasons described above, it is necessary to add a complicated mechanism in order to realize the performance improvement independent of the connection configuration.

The present invention provides a flow control method and method using token passing that does not complicate the functions of the computer and that responds to load fluctuations on the receiving computer.

[0010]

According to the present invention, there is provided a flow control method based on token passing, comprising: a token ring;
A source computer connected to the token ring, and a receiving computer connected to the token ring, wherein the transmitting computer sends a set of data and a busy token addressed to the receiving computer to the token on the downstream side. Sending means for sending to the ring, and relay means for sending the set as it is to the downstream token ring as it is when the set sent by itself is received from the upstream token ring, wherein the receiving computer comprises:
When the set is received from the upstream token ring, if the receiving computer has no room to receive, the relay means for transmitting the set as it is to the downstream token ring, and the set is received from the upstream token ring. When the receiving computer has room for receiving,
A receiving unit that receives the data in the set.

[0011] In the flow control method based on token passing according to the present invention, in the flow control method based on token passing described above, the receiving computer transmits the data to the transmission source computer when the receiving means receives the data. A response unit for transmitting a busy token as a confirmation response to the token ring downstream is further provided.

Further, the flow control method based on token passing according to the present invention is characterized in that, in the flow control method based on token passing described above, the sending means is activated on condition that a free token is received.

A flow control method by token passing according to the present invention is a flow control by token passing performed in a token ring, a transmission source computer connected to the token ring, and a receiving computer connected to the token ring. A sending step in which the source computer sends a set of data and a busy token destined for the receiving computer to the token ring downstream; and when the receiving computer receives the set from an upstream token ring. In the case where the receiving computer has no margin for reception, a relay step of transmitting the set as it is to the token ring downstream, and the source computer receives the set transmitted by itself from the upstream token ring. Sometimes, the pair Or a relay step of transmitting the token ring downstream, the receiving computer,
Receiving the set from the upstream token ring and receiving the data in the set if the receiving computer has room to receive the data.

Further, in the flow control method based on token passing according to the present invention, in the flow control method based on token passing described above, if the receiving means receives the data, the receiving computer transmits the data to the source computer. The method further includes a response step of transmitting a busy token as an acknowledgment to the token ring downstream.

Further, a flow control method based on token passing according to the present invention is characterized in that in the flow control method based on token passing described above, the sending step is started on condition that a free token is received.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Normally, when a receiving computer cannot receive data addressed to its own computer due to an internal load condition, it notifies a transmission error to a transmission source computer, and the transmission source performs retransmission processing and the like. Will be.

However, each of the receiving computer and the transmission source computer has the following functions: (1) the own computer reproduces and relays the busy token of the destination without any processing; and (2) the own computer reproduces and relays the busy token of the transmission source. By providing the function according to the present invention, a transmission error due to a load state inside the computer can be avoided, which can contribute to simplification of the device.

As shown in FIG. 1, computers 1 to 3 are connected to a token ring type loop transmission path 4, and each computer can communicate by acquiring a free token. Further, data transmission between the computers can be performed in a conventional manner as shown in FIG.

The operation of the present invention will be described with reference to the operation of transmitting data from the computer 1 to the computer 3 between computers connected in the configuration shown in FIG. That is, the transmission source 21 in FIG. 2 corresponds to the computer 1, and the reception side 22 corresponds to the computer 3.

[1]. In the token ring type LAN, it is necessary to acquire a free token circulating on the loop transmission path 4 when performing transmission. As shown in FIG. 3, the computer 1 corresponding to the transmission source acquires the free token 10.

[2]. Since the computer 1 has acquired the free token, the transmission data addressed to the computer 3 is transmitted together with the busy token as shown in FIG.

[3]. The busy token 11 transmitted from the computer 1 reaches the computer 3 while being reproduced and transferred by each computer on the loop transmission path 4. At this time, if the computer 3 has a sufficient margin (if there is a reception margin), the busy token is received, and the transmission is completed normally without any problem. If the operation is completed normally, the process of [6] is performed.

[4]. If the computer 3 cannot receive the busy token and receive the data addressed to the computer 3 due to an internal load state or the like (when there is no allowance), the conventional method reports an error. . Therefore, the function of the present invention allows the own computer (in this case, the busy token 12
Is reproduced and relayed in the same manner as when the message is not addressed to the own computer. Also, the computer 1 which is the transmission source does not respond with the busy token 12 transmitted by the own computer (in this case, the computer 1) as an error, and performs the reproduction relay as it is. 6 and 5 show this state.

[5]. If the computer 3 recovers to a receivable state while repeating the reproduction relay as shown in [4] and each figure, the computer 3 receives the busy token 13 addressed to itself as shown in FIG. , Data can be received. That is, the transmission of the data 23 from the transmission source 21 to the reception side 22 in FIG. 2 is completed.

[6]. The busy token 13 from which the data addressed to the computer 3 has been extracted is
As the acknowledgment 24 in FIG. 2, the busy token 14 is transmitted to the computer 1 as shown in FIG. Further, the computer 1 receives this acknowledgment and releases the busy token as the free token 15 as shown in FIG. 9, thereby completing all the processes in the data transmission and completing the process shown in FIG. Become.

In the present embodiment, three computers are connected to the loop transmission path 4, but they can be used regardless of the number of connections.

[0027]

The greatest effect of the present invention is to reduce the load of retransmission processing by a computer in a token ring LAN by avoiding transmission errors due to the load state inside the computer.

Normally, a transmission error is reported to the sending computer when the receiving computer cannot receive the busy token. The transmission source computer received a transmission error, and had to perform retransmission processing, etc., which was a considerable burden on the transmission source computer, but the present invention can reduce the burden on the transmission source computer. I can do it. In addition, when the processing function at the time of transmission error is processed by hardware,
The burden at the time of development was not small, such as an increase in the scale of the device. However, the present invention simplifies the function relating to transmission errors, so that the device can be simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a token ring in which a flow control method based on token passing is performed according to an embodiment of the present invention and a computer connected thereto.

FIG. 2 is a sequence diagram showing signals transmitted and received between a transmission source computer and a reception side computer according to the embodiment of the present invention.

FIG. 3 is a first diagram illustrating an operation of a flow control method using token passing according to an embodiment of the present invention.

FIG. 4 is a second diagram illustrating the operation of the flow control method using token passing according to the embodiment of the present invention.

FIG. 5 is a third diagram illustrating the operation of the flow control method based on token passing according to the embodiment of the present invention.

FIG. 6 is a fourth diagram for explaining the operation of the flow control method based on token passing according to the embodiment of the present invention.

FIG. 7 is a fifth diagram for explaining the operation of the flow control method based on token passing according to the embodiment of the present invention.

FIG. 8 is a sixth diagram illustrating the operation of the flow control method using token passing according to the embodiment of the present invention.

FIG. 9 is a seventh diagram illustrating the operation of the flow control method based on token passing according to the embodiment of the present invention.

[Explanation of symbols]

 1-3: Computer 4: Loop transmission path (token ring) 10: Free token 11: Busy token 12: Busy token 13: Busy token 14: Busy token 15: Free token 21: Source computer 22: Receiving computer 23: Transmission data 24: Confirmation response to transmission data

Claims (6)

[Claims] 1. A token ring, a transmission source computer connected to the token ring, and a reception computer connected to the token ring, wherein the transmission source computer transmits data addressed to the reception side computer Sending means for sending a set of busy tokens to the token ring downstream; and relay means for sending the set as it is to the token ring downstream when the set sent by itself is received from the upstream token ring; When the receiving computer receives the set from the upstream token ring, if the receiving computer has no reception margin, relay means for sending the set to the downstream token ring as it is, When the set is received from an upstream token ring, the receiving computer A flow control method based on token passing, comprising: receiving means for receiving the data in the set if there is room. 2. The flow control method based on token passing according to claim 1, wherein the receiving computer sends a busy token as an acknowledgment response to the transmission source computer when the receiving unit receives the data. A flow control method based on token passing, further comprising a response unit for sending the token ring to a downstream token ring. 3. The flow control method based on token passing according to claim 1, wherein said sending means is activated on condition that a free token is received. 4. A flow control method by token passing performed in a token ring, a transmission source computer connected to the token ring, and a receiving computer connected to the token ring, wherein the transmission source computer is A sending step of sending a set of data and a busy token addressed to a receiving computer to the token ring downstream; and, when the receiving computer receives the set from the upstream token ring, the receiving computer has a reception margin. If not, a relaying step of sending the set as it is to the downstream token ring, and when the source computer receives the set sent by itself from the upstream token ring, the source computer sends the set as it is to the downstream Relaying step for sending to the token ring And the receiving computer receiving the set from an upstream token ring, and receiving the data in the set if the receiving computer has room to receive. Characteristic flow control method by token passing. 5. The flow control method based on token passing according to claim 4, wherein the receiving computer sends a busy token as an acknowledgment to the source computer when the receiving means receives the data. A flow control method by token passing, further comprising a response step of sending the token ring to a downstream token ring. 6. The flow control method based on token passing according to claim 4, wherein the sending step is started on condition that a free token is received.