JPH04199941A - Congestion control method for inter-network repeating installation - Google Patents

Abstract

PURPOSE:To reduce the abolishment of frames and to improve throughput by improving priority in the medium access control auxiliary layer of a communication protocol and prohibiting the transmission of data from the terminal of low priority when a prescribed congested state is detected. CONSTITUTION:A repeating installation 1 connects the network 2 of a token passing system with another network 3 and only terminals (a)-(c) having a transmission right transmit data since the network 2 of the token passing system prevents the contention of communication. The repeating installation 1 repeats the frames between the networks 2 and 3 by the medium control auxiliary layer in the data link layer of the communication control protocol. When the congested state is detected during repeating, priority provided in a priority field in the frame of the medium access control auxiliary layer is set high and a transmission request from the other terminal (d) is excluded. Thus, the abolishment of the frames is reduced and throughput can be improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a token passing network,
The present invention relates to a congestion control method for an inter-network relay device that connects to other networks.

(Conventional technology) Conventionally, multiple LANs (local area networks)
There exists an inter-network relay device that interconnects networks such as
18 (Vl, 0) "Information Processing Interoperability Technology Association", "Information Processing Society of Japan 39th (Late 1989) National Conference, p. 1920", r GLOBCOM'88 198
November 8, page 1791). In particular, the inter-LAN relay device transmits frames received from one network to the media control sublayer (MAC) of the data link layer of the communication control protocol.
Filter and route by address (sublayer). Therefore, there is no need to implement protocols higher than the logical link sublayer. Therefore, high-speed relay can be performed.

Here, filtering refers to a function of checking the address of a received MAC frame and verifying whether or not the frame is to be relayed. Also, what is routing?
It refers to interconnecting LANs at the network layer.

(Problems to be Solved by the Invention) However, the above-described conventional technology has the following problems.

That is, the above-mentioned relay device was only equipped with a filtering database learning function in addition to a filtering function and a routing function. In other words, wheel axle control was not performed during times of high traffic. Here, the term "wheel drive" refers to a request for communication that exceeds the communication capability of a relay device or the like. Control of the wheel axle is usually realized by a protocol at a layer higher than the logical link sublayer.

However, in the above-mentioned relay device, protocol processing of layers higher than the logical link sublayer was omitted in order to realize high-speed communication. Due to these circumstances, when a wheel spindle occurs in the above-mentioned relay device, frames are discarded, resulting in a problem that communication performance deteriorates.

The present invention has been made with the above points in mind, and in order to perform high-speed communication, even during high traffic when the protocol processing of the communication layer higher than the logical link sublayer is omitted, there are fewer discarded frames and a higher throughput. The purpose of this invention is to provide an excellent line axis control method for an inter-network relay device.

(Means for Solving the Problems) A wheel shaft control method for an inter-network relay device according to the present invention provides a method for controlling a wheel set of a relay device between networks, which connects a token-passing type network in which only a terminal having the transmission right can transmit data and another network to a relay device. The relay device is connected by
Relaying frames between the networks by a medium control sublayer of a data link layer of a communication control protocol;
If a wheel axle condition is detected during the relay, the priority provided in the priority field in the frame of the medium control sublayer is set high.

(Function) In the wheel set control method for an inter-network relay device of the present invention, when the number of transmissions from a plurality of terminals connected to a network to terminals on other networks increases, and the inter-network relay device enters a wheel set state, a frame The priority field in the middle is set to a high priority. This priority field is provided for optional use. Using this priority field, when the priority is set high, transmission requests from other terminals within the network are excluded. This prevents wheelset and
This can prevent deterioration in communication performance.

(Example) FIG. 1 is a connection diagram of a relay device using the method of the present invention.

As shown in the figure, a relay device 1 connects a token passing network 2 and another network 3.

The token passing network 2 is designed so that only a specific terminal can transmit data in order to prevent communication conflicts. That is, the token passing method is a method in which data collisions do not occur on the transmission path of the network by mutually exchanging transmission rights called tokens. The tokens are circulated within the network 2 one or more predetermined times.

Another network 3 is connected to network 2 via relay device l.

The relay device 1 relays frames between the networks 2 and 3 using the medium control sublayer of the data link layer of the communication control protocol. The communication control protocol is, for example, ○
This is due to SI (Open System Interconnection).

The communication functions of open systems are modeled in seven layers. One of these layers is the data link layer. The data link layer consists of a logical link control sublayer and a medium access control sublayer. The logical link control sublayer is a communication layer that transmits and receives logical data. The media access control sublayer is a communication layer that allows access to storage media such as magnetic disks.

If the relay device 1 detects a wheel axle state while performing such relay, it sets a high priority in the priority field in the frame of the medium access control sublayer. The priority field in the medium access control sublayer frame is provided for arbitrary use by the user.

In the present invention, the priority set in the priority field of the frame to be transmitted is set and controlled according to the wheel axle state of the relay device 1 as shown in (1) and (2) below. Here, the wheel axle state refers to a state in which the capacity of the communication buffer of the relay device 1 is close to full, for example, 80%.

■If the relay device l is not in the wheel set state, set the priority low. As a result, all terminals a, b,
c are equally given the right to transmit.

(2) When the relay device 1 is in a wheel set state, the priority is set high. This allows only devices that can transmit with high priority, including relay device 1, to obtain the right to transmit. Therefore, for general terminals, transmission is prohibited.

This releases the wheel set and prevents the frame from being discarded due to the generation of the wheel set.

Hereinafter, the wheel axle control method of the present invention will be sequentially explained with reference to the flowchart of FIG. 2 and the operation example of FIG. 3.

FIG. 2 is a flowchart showing the wheel set control operation procedure of the relay device.

In this figure, the processing is roughly divided into the following three types.

■Processing corresponding to the event (reception process, transmission completion process) (steps 5l-54) ■Line axis determination process (step S5) ◎Transmission process (steps 36 to 512) Among these, the present invention If it is determined that the transmission process (steps 86 to 12) is in a wheel spindle state, the priority value set in the priority field of the frame is set high in step S.
6), transmit the data (steps 87 to S9). At this time, if there is data to be transmitted, that data is transmitted, or if not, dummy data is generated (step S8).
Send this data. Sending dummy data when there is no data to be sent is due to the frame priority in the medium access control sublayer being set high, but if no data is actually being sent, the control of other communication layers is required. This is because there is a possibility that the priority of the frame in the medium access control sublayer may be lowered due to the above reasons.

By sending such high priority data,
Suppresses transmissions from other terminals and attempts to release the wheel spindle state.

Next, an example of the operation of wheel axle control will be shown with reference to FIG.

FIG. 3 is a diagram showing an example of wheel axle control operation of the relay device.

The left side of this figure shows the network state at each time point T1 to Tll, and the flowchart on the right side of this figure shows the operation procedure of the relay device corresponding to the left side state. In the operation example shown in this figure, the initial conditions are determined as follows.

Terminals a, b, and c all have a plurality of pieces of transmission data that should be relayed by the relay device, and upon receiving a low-priority fleet token, they immediately transmit the data.

It is assumed that the relay device is not in the congestion state at the moment, but will be in the wheel drive state after receiving one more frame.

The relay device has a plurality of pieces of data to be transmitted to the LAN to which terminals a, b, and c belong.

Next, the operation in this initial state will be explained along each time point Tl to Tll.

At time T1, the terminal a is in a non-wheel drive state and transmits data. At this time, the priority P of the token is
It is L (low), and the token's reserve priority R is also L. Reserve priority R
is information set to reserve a change when the priority P cannot be changed. On the other hand, at this time, the relay device is in a data reception waiting state.

At time T2, the relay device receives data from terminal a. At this time, the network is in a state of axle, and the relay device requests data transmission with high priority.

At time T3, terminal a removes the transmitted data and transmits a low priority fleet token. This low priority fleet token is received by the terminal.

At time T4, the terminal that received the free token from terminal a transmits data.

At time T5, the relay device receives the data from b and sets the reserve priority R of the token reserve field in the frame to H (high).

At time T6, the terminal removes the transmitted data and transmits a high priority fleet token.

At time T7, terminal C cannot transmit due to the high priority Fleet-Kun, so the relay device obtains the transmission right and transmits the data.

At time T8, the relay device removes the transmitted data and continues transmitting data with high priority unless the wheel set state is released.

At time T9, when the relay device enters the non-convergence state, it transmits a high priority free token.

At time TIO, the priority of the terminal unit is changed from high to low.

At time Tll, terminal C transmits data in response to a low priority fleet token.

In the above-described embodiments, a ring type network has been described as the token passing type network, but the present invention is not limited to this, and it goes without saying that a bus type network or the like may be used.

(Effects of the Invention) As explained above, according to the wheel set control method for an inter-network relay device of the present invention, when a predetermined wheel set state is detected, the priority in the medium access control sublayer of the communication protocol is increased. Therefore, data transmission from low-priority terminals is prohibited, which has the following effects.

(2) Even if the relay device is in a wheel drive state, the number of frames that are discarded without being received by the relay device is reduced, and stable throughput can be obtained.

(2) When a frame is discarded, the frame is retransmitted according to the communication protocol of the upper communication layer, but it is possible to reduce the burden on the network due to such retransmission.

- When a relay device connects a LAN and a public network, retransmitted frames are also subject to public network charges, but by reducing the number of retransmissions, the usage of the public network can be reduced accordingly.

[Brief explanation of the drawing]

Figure 1 is a connection diagram of a relay device using the method of the present invention;
The figure is a flowchart showing the operation procedure for wheel axle control of the relay device, and FIG. 3 is a diagram showing an example of the wheel axle control operation of the relay device. l... Relay device, 2... Token passing network, 3.
...Other networks. Patent Applicant: Oki Electric Industry Co., Ltd., Agent: Toshiaki Suzuki -1/-:2゛(

Claims (1)

[Scope of Claims] A token-passing network that allows only terminals with transmission rights to transmit data is connected to another network by a relay device, and the relay device uses data link layer of a communication control protocol. The medium control sublayer of the media control sublayer relays frames between the networks, and if a congestion state is detected during the relaying, the priority set in the priority field in the frame of the medium control sublayer is A congestion control method for an inter-network relay device characterized by setting the congestion to a high level.