JPH0591120A - Local area network - Google Patents

Abstract

PURPOSE:To expand the transmission capacity of data transmission and system configuration in a ring LAN (local area network) of the token passing system and to improve the utilizing efficiency of an optical loop transmission line. CONSTITUTION:Three transmission lines 10, 11, 12 are employed, the one of them is used for an optical loop transmission line 10 through which a token is circulated clockwise, the other one is used for an optical loop transmission line 11 through which a token is circulated counter clockwise, and the rest one is used for a standby optical transmission loop line 12 when any of the two optical loop transmission lines is faulty, and when a fault is detected from any of the two optical loop transmission lines 10, 11, loop interface devices 1, 2, 3, 4 are used to changeover the faulty line into the standby optical loop transmission line 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for data transmission and system configuration of a token passing ring LAN (local area network). The present invention is
The present invention relates to a local area network capable of expanding transmission capacity and improving usage efficiency.

[0002]

2. Description of the Related Art A conventional loop type LAN has two optical loop transmission lines, which are used as a normal operation transmission line.
One of the two optical loop transmission lines is always used to transmit the token in a fixed direction, and the other one is used as a substitute when a failure occurs.

When the loop interface monitoring device detects that the optical loop transmission line used as the active transmission line has some trouble, the optical loop transmission line currently used for data transmission is said to be unusable. Judgment is made and recovery from the failure is performed by switching the backup optical loop transmission path as a working transmission path as a countermeasure against the failure.

Further, when the loop interface monitoring device detects that both of the transmission lines have failed due to the disconnection accident of the optical loop transmission line, the loop interface monitoring device uses the two optical loop transmission lines in front of the failure point. By folding back, it is separated from the faulty part.

[0005]

In the above-mentioned system configuration of the conventional token passing type ring LAN, two optical loop transmission lines are provided, but one optical loop transmission is provided for normal data transmission. Since one line is used and the other one is used only when a failure occurs, the transmission capacity is reduced by half even though two optical loop transmission lines are used, and the efficiency of use is improved. Is getting worse.

Further, since the tokens always flow in a fixed direction in the operating system transmission path, when a frame is transmitted from one loop interface device to the adjacent loop interface device, the tokens progress in opposite directions. If so, you have to wait for the token to go around,
During that time, there is a problem that the token cannot be used for other loop interface devices.

The present invention solves such a problem, and an object of the present invention is to provide a network capable of expanding the token transmission capacity and improving the use efficiency of the transmission path.

[0008]

The present invention provides a local area network comprising an optical loop transmission line and a plurality of loop interface devices connected to the optical loop transmission line for transmitting and receiving data. The path is composed of three lines, one of which is a working data transmission line in which the token goes around in a clockwise direction, and the other one is a working data transmission line in which the token goes around in a counterclockwise direction. The remaining one is arranged as an alternative standby data transmission line, and when a failure is detected in any of the active data transmission lines in the loop interface device, it is switched to the standby data transmission line. It is characterized in that a switching means is provided.

The switching means of the loop interface device includes a pair of transmission path selection circuits for selecting a bypass state of an operation system or a standby system of the data transmission path, a pair of transmission / reception relay circuits for transmitting / receiving a frame, and a frame A pair of logic control units for processing contents; and a pair of bypass transmission lines for relaying the active transmission line through the transmission line selection circuit when a bypass circuit is selected by the transmission line selection circuit. Is desirable.

[0010]

[Operation] A transmission line is composed of three optical loop transmission lines, one of which is a data transmission line in which a token circulates clockwise, and the other one is a data transmission line in which a token circulates counterclockwise. Furthermore, the remaining one is placed as a substitute for when a failure occurs in either the clockwise or counterclockwise data transmission line, and when an abnormality is detected, it is set as the substitute data transmission line. Switch and connect.

As a result, the transmission capacity can be increased, the utilization efficiency of the standby transmission line can be improved, and if at least one of the optical loop transmission lines fails, at least one is normal. Data transmission can be continued. Further, since it can be used in either left or right direction, the transmission distance between the loop interface devices can be minimized.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

In the embodiment of the present invention, the optical loop transmission line is composed of three lines, one of which is used as the operational data transmission line 10 in which the token circulates in the clockwise direction, and the other one in the counterclockwise direction. As an operating optical loop transmission line 11 and the remaining one as a standby optical loop transmission line 12 as a substitute, and the loop interface devices 1, 2, 3 and 4 are provided with an operating system. When a failure is detected in any one of the optical loop transmission lines 10 or 11 of (1), a switching means for switching to the standby optical loop transmission line 12 is provided.

Next, the operation of the embodiment of the present invention thus constructed will be described.

In normal times, the optical loop transmission lines 10 and 11 are used as an operating system for data transmission, and the optical loop transmission line 10 is rotated clockwise between the loop interface devices 1, 2, 3 and 4. Existing tokens,
The frame 201 is transmitted in the direction of arrow A. Further, the optical loop transmission line 11 supplements the counterclockwise rotating token and transmits the frame 202 in the direction of arrow B. At this time, the optical loop transmission line 12 is the two optical loop transmission lines 1
Loop interface devices 1, 2, 3 and 4 as countermeasures against failures when an abnormality is detected in either 0 or 11
Is connected in a logically disconnected state.

FIG. 2 is a diagram for explaining the configuration and data transmission of the two loop interface devices in the embodiment of the present invention.

The loop interface device 1 is an operation system,
Transmission path selection circuits 21 and 2 for selecting the standby system bypass state
2, and a transmission / reception relay circuit 100 that transmits and receives frames,
101 and a logic control unit 11 for processing the contents of the frame
1 and 110, and bypass transmission lines 31 and 32 for relaying the optical loop transmission lines 10 and 11 of the operating system by the transmission line selection circuits 21 and 22 when in the bypass state. Another loop interface device 2 shown in FIG.
3 and 4 are similarly constructed.

When transmitting a frame from the loop interface device 1 to the loop interface device 2,
First, the loop interface device 1 includes the logic control unit 11
Information for the loop interface device 2 is created by means of 1 and 110, and the frame is sent to the transmission / reception relay circuit 101 or 100 that is transmitting / receiving a frame. At that time, information indicating that the transmission destination is the loop interface device 2 is set in the frame.

It is more efficient for the transmission / reception relay circuit 101 or 100 which receives the frame to transmit data through the optical loop transmission line 10 for the counterclockwise rotation, or through the optical loop transmission line 11 for the clockwise rotation. Whether the data transmission is more efficient is selected according to the distance to the destination loop interface device 2. For example, if the optical loop transmission line 10 is selected, the optical loop transmission line 10 is rotated clockwise. It is confirmed that the loop interface device 1 has supplemented the token that is being processed, and the frame is transmitted to the optical loop transmission line 10 through the transmission line selection circuits 21 and 22.

When the loop interface device 2 receives the frame flowing through the optical loop transmission line 10 or 11 of the operating system, it relays the transmission line selection circuit 23 or 24 and takes it into the transmission / reception relay circuit 102 or 103. The transmission / reception relay circuit 102 or 103 analyzes the frame, and if the transmission destination is the loop interface device 2, the logical control unit 112.
Alternatively, the process of loading in 113 is performed. If the destination is not the loop interface device 2, the received frame is sent to the optical loop transmission line 10.

When an abnormality occurs in the optical loop transmission line 10 of the operating system between the loop interface device 1 and the loop interface device 2 during system operation, the transmission line selection circuits 21 and 22 of the loop interface device 1 are operated. System optical loop transmission line 10 through transmission / reception relay circuits 101, 10
It is separated from 0 and the loop interface device 2
The transmission path selection circuits 23 and 24 disconnect the operating optical loop transmission path 10 from the transmission / reception relay circuits 103 and 102, switch to the optical loop transmission path 12 for fault countermeasures, and switch the loop interface device 1 and 2 transmits and receives frames.

[0022]

As described above, according to the present invention, the ring LAN of the token passing system is constituted by two data transmission lines and one fault countermeasure transmission line. The transmission capacity can be doubled by the number of installation steps, and the utilization efficiency of the standby transmission line can be improved.

If one of the three optical loop transmission lines fails, the LAN system can be operated with the same configuration as usual, and at least one of the three optical loop transmission lines can be operated. If the book is normal, the same performance as the conventional one can be exerted, so that the availability can be enhanced.

Furthermore, since the token can be transmitted clockwise or counterclockwise, the distance between the loop interface device for transmitting and the loop interface device for receiving can be shortened, and the token occupancy rate for one frame can be reduced. There is an effect that it can be lowered.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration and data transmission of two loop interface devices according to an embodiment of the present invention.

[Explanation of symbols]

1, 2, 3, 4 Loop interface device 10, 11, 12 Optical loop transmission line 21, 22, 23, 24, 25, 26, 27, 28
Transmission path selection circuit 31, 32, 33, 34 Bypass transmission path 100, 101, 102, 103 Transmission / reception relay circuit 110, 111, 112, 113 Logic control unit 131 Optical cable 201, 202 Frame

Claims (2)

[Claims] 1. A local area network comprising an optical loop transmission line and a plurality of loop interface devices connected to the optical loop transmission line for transmitting and receiving data, the optical loop transmission line comprising three optical loop transmission lines, One of them is a working data transmission line in which the token circulates clockwise, the other one is a working data transmission line in which the token circulates counterclockwise, and the remaining one is used as a substitute. The standby interface data transmission path, and the loop interface device is provided with switching means for switching to the standby data transmission path when a failure is detected in any of the active data transmission paths. And a local area network. 2. The switching means of the loop interface device comprises a pair of transmission path selection circuits for selecting a bypass state of an active system or a standby system of the data transmission path, a pair of transmission / reception relay circuits for transmitting / receiving a frame, A pair of logic control units that process the contents of the frame, and a pair of bypass transmission lines that relay the active transmission line through the transmission line selection circuit when the bypass circuit is selected by the transmission line selection circuit. The local area network of claim 1, including: