JPS6390230A - Repeating installation - Google Patents

Abstract

PURPOSE:To avoid the fault of the whole of a system by preventing an abnormality from having an influence upon the other all network systems and disconnecting only a faulty part if the abnormality occurs in a part constituting the network system. CONSTITUTION:If an illegal modulated waveform is continuously received and normal transmission cannot be performed for a long time because of the occurrence of trouble in a bus type transmission line 22, a signal monitor circuit 4 of remote repeaters 26 and 27 connected to the bus type transmission line 22 detects the signal abnormality of the bus type transmission line 22. Then, the signal monitor circuit 4 de-energized a permission signal 12, and conditions are not satisfied in either of a transmission gate 5 and a reception gate 8, and the output is not energized. Consequently, the bus type transmission line 22 is disconnected from the other network systems. Thus, the system is degenerated to the network system having only a bus type transmission line 21 and network systems having bus type transmission lines 23 and 24 and continues the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a relay device for connecting network systems each including a plurality of transmission devices connected via a communication medium.

[Prior Art] In recent years, inexpensive LANs (Local Area Networks) that use conductive communication media, such as metal wires, as bus transmission paths have become popular.
In particular, the higher the frequency of the signal, the greater the attenuation of the signal level.
Furthermore, the transmission distance cannot be increased due to the influence of external noise. However, many users are requesting longer transmission distances. Therefore, in response to the request of these users to extend the transmission distance, a relay device called a so-called remote repeater is used to connect multiple short transmission distance bus transmission lines using optical fibers to form a wide area network. The device has been commercialized.

An example of the configuration of this wide area network system is shown in FIG.

This enabled LAN users to communicate with remote locations and further increased the profitability of LANs.

[Problems to be Solved by the Invention Something similar to a collimated repeater is a so-called bridge or gateway. These devices have internal circuits such as a CPU that can make decisions and control, and even perform part of the protocol conversion between networks. On the other hand, the remote repeater generally performs only a simple signal relay and is not concerned with the contents of data at all.

Therefore, if multiple bus transmission lines are connected using a remote repeater, the remote repeater simply relays signals as described above, so if one LA
If a failure occurs in the N bus transmission line and an abnormal signal flows out of the transmission line, this abnormal signal will be transmitted to other transmission lines one after another via the remote repeater, causing the entire wide area network system to go down. There is a risk.

In addition, the length of the optical fiber connected to a remote repeater can be several kilometers long, and when bus transmission lines scattered far apart are connected using a remote repeater, the above-mentioned failures may occur anywhere in the network. It takes time to determine where the problem occurred, which may delay recovery.

[Means for Solving the Problems] The present invention has been made for the purpose of eliminating the above-mentioned problems, and as a means for solving the above-mentioned problems, this embodiment provides and a stop means for stopping the relay processing of the signal when an abnormality in the signal is detected by the monitoring means.

[Operation: In the above configuration, an abnormal signal generated in one of the transmission systems connected by a communication medium is prevented from spreading to other systems via the relay device, and the part where the failure occurs is isolated from the others. .

[Example 1] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a remote repeater according to an embodiment of the present invention. In the figure, 1 is a bus-type transmission line made of a normal conductive communication medium, such as a metal wire, 2 is an optical fiber, and 3 is a bus-type transmission line made of a metal wire. a receiving circuit that receives signals from one bus-type transmission line;
4 is a signal monitoring circuit that monitors the signal of the bus-type transmission line 1, and this signal monitoring circuit 4 is a circuit that detects an abnormality in the transmission signal using hardware, and the detection methods include the following. .

■ Is the signal being received continuously for a long time and not occupying the transmission path?

■ Are illegal modulation waveforms being received continuously?

■ Is there any abnormal voltage level on the transmission path?

etc. will be checked. Then, when the above abnormality is not detected, a relay permission signal 12 is output.

Reference numeral 5 denotes a transmission gate, which is an AND circuit, which allows outputting of the received signal from the reception circuit 3 to the light emitting element 6 according to the permission signal 12 from the signal monitoring circuit 4; A light emitting element converts the signal into an optically modulated signal and outputs it to the optical fiber cable 2, and 10 is an LE that displays the state of the permission signal 12 (displays the signal state of the bus-type transmission line 1).
A display device consisting of D, etc., 7 is an optical fiber cable 2
A receiver 8 is an AND circuit that allows the electrical signal 13 from the light receiving element 7 to be outputted to the bus type transmission line 1 in accordance with the permission signal 12. A gate 9 is a transmitting circuit that transmits the signal from the receiving gate '8 to the bus-type transmission line 1.

FIG. 2 shows a configuration diagram of a wide area network system including a remote repeater having the above configuration.

As shown in FIG. 2, a large number of transmission control devices are connected to each of the bus type transmission lines 21 to 24, and each transmission line constitutes one network system. Each network system is connected to each other via remote repeaters 25 to 30 having the configuration shown in FIG. 1 and optical fibers. As a whole, it constitutes a wide area network system.

The operation of the remote repeater of this embodiment having the above configuration will be described below.

When data transmission is normally performed on any of the bus-type transmission lines 21 to 24 in FIG. The transmission signal is converted from electrical to optical and optical to electrical between all bus type transmission lines 2
1 to 24 operate as if they were connected to each other.

Here, a failure occurs in the bus type transmission line 22 shown in Fig. 2, and an abnormal signal flows, for example, an illegal modulation waveform is continuously received, resulting in a situation where normal transmission cannot be carried out for a long time. Let's explain the case. In this case, the signal monitoring circuits 4 of the remote repeaters 26 and 27 connected to the bus type transmission line 22 detect a signal abnormality on the bus type transmission line 22. As a result, the signal monitoring circuit 4 deactivates the permission signal 12. Therefore, both the transmitting gate 5 and the receiving gate 8 are no longer satisfied and the output is not activated. Therefore, the bus type transmission line 22 is separated from other network systems,
The wide area network system shown in FIG.
It is possible to continue operation while degenerating into a network system with 4 network systems, thereby preventing the entire wide area network system shown in FIG. 2 from going down.

At this time, the signal monitoring circuit 4 continues to monitor the state of the bus-type transmission line 22, and when the bus-type transmission line 22 returns to the normal state, it energizes the permission signal 12 again, and the transmission gate 5 and The receiving gate 8 is satisfied, and the entire network system shown in FIG. 2 becomes operational.

Note that when the signal monitoring circuit 4 detects an abnormality in the bus-type transmission line, this fact is displayed on the display device 10, so by looking at the display status of the display device 10, you can check whether the remote repeater is connected. It is possible to immediately determine whether the bus type transmission line is operating normally or whether a failure has occurred, and prompt failure recovery processing can be performed. In other words, it can be determined that there is a fault in the bus transmission line with the above display for all connected remote repeaters.

[Effects of the Invention] As explained above, according to the present invention, even if an abnormality occurs in one part of a network system, this abnormality does not spread to all other network systems and only the faulty part can be disconnected. This can prevent the entire system from going down.

Furthermore, by providing a means for notifying the part where the failure has occurred, prompt failure recovery can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention; Fig. 2 is a diagram of a wide area network system having the configuration shown in Fig. 1; It is a connection network system diagram with a bus-type transmission line. In the figure, 1, 21 to 24... Bus type transmission line, 2... Optical fiber, 3... Receiving circuit, 4... Signal monitoring circuit,
5... Transmission gate, 6... Light emitting element, 7... Light receiving element, 8... Receiving gate, 9... Transmitting circuit, 10...
...Display device, 12...Permission signal, 25-30...
Remote repeater, D...transmission control device. Patent applicant: Canon Corporation・'J・−≦− Figure 2

Claims (3)

[Claims] (1) A relay device for interconnecting a network system formed by connecting a plurality of transmission devices via a communication medium, comprising a monitoring means for monitoring the state of a signal to be relayed and transmitted; 1. A relay device comprising a stop means for stopping signal relay processing when a signal abnormality is detected. (2) The relay device according to claim 1, further comprising notification means for notifying the stoppage of the relay processing by the stop means. (3) A relay device is a device that converts signals between a conductive communication medium and an optical fiber cable in order to connect a network system consisting of a plurality of transmission devices connected via a conductive communication medium with an optical fiber cable. A relay device according to claim 1 or 2, characterized in that: