JPH06188896A - Fault monitoring device - Google Patents

Abstract

PURPOSE:To easily monitor the transmission lines of existent and reserve systems with high reliability. CONSTITUTION:This device is provided with a line switching part 3 for switching return connection from a transmission line L1 of the existent system shown by a broken line through a transmission line L2 of the reserve system and when a token possession detecting circuit 7 possesses a token frame in the case of monitoring the fault of the transmission line L2 of the reserve system while performing communication by using the transmission line L1 of the existent system, under the control of a switching control part 6, the line switching part 3 performs the return connection after a temporary transmission stop circuit 8 temporarily stops transmission, a prescribed frame and the token frame are circulated through the return connected duplex ring transmission lines L1 and L2 from a fault monitor part 5 after this return connection and based on the prescribed returned frame, the faults of the duplex transmission lines L1 and L2 are monitored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault monitoring apparatus for a communication system composed of a plurality of stations connected to a dual ring transmission line of an active system and a standby system.

[0002]

2. Description of the Related Art Conventionally, a fault monitoring system in a communication system consisting of a plurality of stations connected to a dual ring transmission line of an active system and a standby system, provides a monitoring station for monitoring in the transmission line,
The failure of the transmission path is monitored by monitoring the monitoring signal sent from this monitoring station and circulating around the transmission path.

However, the fault monitoring by this monitoring station is limited to the monitoring of only the transmission line of the active system, and the transmission line of the standby system is hardly monitored in the normal state. After a considerable amount of time has passed, a failure may have occurred during this period, and a failure has actually occurred in the transmission path of the active system, and as a result of failure monitoring when switching to the transmission path of the standby system, When a failure occurs, a situation occurs in which the backup transmission line cannot be used, and there is a problem that the backup transmission line is meaningless.

On the other hand, for example, Japanese Patent Laid-Open No. 55-161.
Japanese Patent No. 449 discloses a fault monitoring method capable of sufficiently enhancing the reliability of a backup transmission line by sending a monitoring current not only to the working transmission line but also to a backup transmission line to constantly monitor the presence or absence of a failure. Is listed.

However, in the above fault monitoring system, the monitoring signals in the working and protection input transmission lines are respectively extracted to determine the presence / absence of a fault in each transmission line, that is, the transmission line of the working system. Since the transmission lines of the backup system are individually monitored, there is a problem that a special fault monitoring device for fault monitoring is required and the configuration for fault monitoring is complicated.

Moreover, the special fault monitoring device needs to be added independently of the normal communication device, and may be independently failed. In this case, there is a high possibility that erroneous fault monitoring will be performed and maintenance will be difficult.

[0007]

As described above, conventionally, the fault monitoring in the communication system including a plurality of stations connected to the dual ring transmission lines of the active system and the standby system is performed by the monitoring station. Only the transmission line is monitored, and the standby system transmission line is rarely monitored under normal conditions.Use the standby system transmission line when you want to actually cause a failure in the active system transmission line. There was a situation that could not be done. Then, in order to solve this problem, a failure monitoring device which individually monitors the active transmission path and the standby transmission path has been considered, but this failure monitoring device has a complicated fault monitoring configuration. At the same time, since the fault monitoring device is independent of the normal communication device, there is a high possibility that the fault monitoring device will independently fail, and in this case, there is a problem that erroneous fault monitoring may occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fault monitoring apparatus which can eliminate such problems and can easily and reliably monitor the transmission paths of the working system and the protection system.

[0009]

DISCLOSURE OF THE INVENTION The present invention is directed to a failure of a dual ring transmission line of a communication system including a plurality of stations connected to dual ring transmission lines of a working transmission line and a standby transmission line. In a fault monitoring device for monitoring, token acquisition means for detecting and acquiring a token frame, switching means for switching a loopback connection from the active transmission path through the backup transmission path, and the token acquisition Switching control means for performing switching control of the loopback connection to the switching means after the token frame of the means is acquired, and a predetermined frame and a token frame are transmitted to the dual ring transmission line after the loopback connection, and the active system and the standby system And a monitoring means for monitoring the failure of the double ring transmission line based on the returned predetermined frame. The features.

[0010]

The present invention has a switching means for switching a loopback connection from a transmission line of the active system via a transmission line of the standby system, and the standby system is used when communication is performed using the transmission line of the active system. In the case of monitoring the transmission line for failure, when the token acquisition unit detects and acquires a token frame, the switching control unit causes the switching unit to make a loop connection, and after this loop connection, a predetermined frame and a token frame. Since the double ring transmission path connected by looping back is looped and the failure of the dual transmission path is monitored based on the returned predetermined frame, it is possible to use a highly reliable working system and a standby system. The transmission line can be easily monitored.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a fault monitoring apparatus which is an embodiment of the present invention.

In FIG. 1, the fault monitor 1 is connected to a dual ring transmission line of a transmission line L1 of a working system and a transmission line L2 of a standby system. Each of the dual ring transmission lines has a different transmission direction. Then, the fault monitoring apparatus 1 uses the input / output unit 2 for converting the transmission line L1 of the active system and the transmission line L2 of the standby system into the transmission form in the fault monitoring device 1, the active system and the standby system via the input / output unit A line switching unit 3 that switches the transmission line of the system and makes a loopback connection from the transmission line L1 of the active system via the transmission line L2 of the standby system, and a transmission / reception unit 4 that performs transmission / reception via the transmission / reception switched by the line switching unit 3. , A fault monitor 5 for processing a frame received from the transmitter / receiver 4 or sending a frame to be transmitted to monitor a fault in addition to normal data processing, and switching or looping back of the transmission lines of the active system and the standby system It is composed of a switching control unit 6 that controls connection switching.

The transmission / reception unit 4 detects the acquisition of a token frame circulating in the dual ring network and sends a token acquisition signal to the switching control unit 6 according to instructions from the token acquisition detection circuit 7 and the switching control unit 6. It has a transmission temporary stop circuit 8 for temporarily stopping transmission.

Here, a mode of connection switching of the line switching unit 3 will be described.

In FIG. 1, first, in a normal state,
Communication is performed using the active transmission line L1. That is, the line switching unit 3 is in the state shown by the solid line,
The terminals a1 and b1, and the terminals a4 and b2 are connected. Therefore, the data, that is, the frame transmitted from the fault monitoring unit 5 is transmitted / received by the transmission / reception unit 4, the terminal b2, and the terminal a.
4, the line switching unit 3, the input / output unit 2, and the terminal c4, and the data is output to the working transmission line L1 and the working transmission line L1.
In the clockwise direction, is input to the input / output unit 2 via the terminal c1, and is further input to the fault monitoring unit 5 via the terminal a1, the line switching unit 3, the terminal b1, and the transmitting / receiving unit 4. In addition, the transmission line L2 of the backup system is also in the state where the terminals a2 and a3 are connected as shown by the solid line. That is, the terminal a3 of the line switching unit 3 is folded back to the terminal a2, and the transmission line L2 of the standby system is circulated counterclockwise through the input / output unit 2 and the terminal c2, and the terminal c3 and the input / output unit 2 are used. Line switching unit 3
Input to the terminal a3 and is returned to the terminal a2 again. Hereinafter, this connection state is referred to as "normal state connection".

On the other hand, in the fault monitoring state, the line switching unit 3 is in the connection state shown by the broken line, that is, the state in which the terminals a1 and b1, the terminals a2 and b2, and the terminals a3 and a4 are connected. . Therefore, the data transmitted from the fault monitoring unit 5 is output to the transmission line L2 of the backup system via the transmission / reception unit 4, the terminal b2, the line switching unit 3, the terminal a2, the input / output unit 2, and the terminal c2. The signal is input to the terminal c3 by rotating counterclockwise around the backup transmission line L21. Further, in the line switching unit 3, the terminal a3 is folded back and connected to the terminal a4, output to the working transmission line L1, and circulates the working transmission line L1 clockwise to be input to the terminal c1.
Further, the input / output unit 2, the terminal a1, the line switching unit 3,
It is input to the fault monitoring unit 5 via the terminal b1 and the transmission / reception unit 4. In this manner, by connecting the terminals a3 and a4 of the line switching unit 3 by folding back, the working transmission line L1 and the protection transmission line L2 are folded back, and the working system and the protection system transmission line are simultaneously disturbed. By monitoring, the failure of the backup transmission line is monitored. The return connection state between the active system and the standby system is hereinafter referred to as "fault monitoring state connection".

Next, the fault monitoring operation of the fault monitoring apparatus 1 will be described with reference to the flowchart.

FIG. 2 is a flow chart of fault monitoring control of the fault monitoring apparatus 1.

First, when the transmission line monitoring for fault monitoring is started, the fault monitoring unit 5 sends a monitoring command to the switching control unit 6. After that, when the token acquisition detection circuit 7 of the transmission / reception unit 4 detects a token frame for frame transmission (step 101), the token acquisition detection circuit 7 sends a token acquisition signal to the switching control unit 6 (step 1).
02). In response to this, the switching control unit 6 sends a standby signal to the transmission suspension circuit 2 of the transmission / reception unit 4 (step 103) to suspend the transmission processing of the transmission / reception unit 4. After that, the switching control unit 6 sends a fault monitoring state connection signal to the line switching unit 3, and the line switching unit 3 receiving this signal
The normal state connection is switched to the fault monitoring state connection (step 104). In other words, the connection is switched to the return connection of the transmission path of the working system and the protection system.

In step 101, the switching control is performed after the token frame is acquired. The ring network can obtain the transmission right only by acquiring the token frame, and the token frame circulating in the ring network is Since it is unique, the acquisition of the token frame does not affect the communication device connected to another ring network.

After the switching of the fault monitoring state connection is completed, the switching control section 6 sends a standby cancellation signal to the transmission temporary stop circuit 8 to cancel the temporary stop of the transmission of the transmission / reception section 4 (step 105). . Then, in this fault monitoring state connection, the fault monitoring unit 5 detects a fault in the transmission path (step 106). The signal used for the fault detection by the fault monitoring unit 5 may be a normal frame format data signal or a special monitoring signal for fault monitoring.

Next, the fault monitoring unit 5 determines whether or not there is a fault based on the fault monitoring result of step 106 (step 107), and only when it is determined that there is a fault, a predetermined fault is notified (step). 108). In this way, failure monitoring of the transmission path L1 of the standby system can be performed by simultaneously monitoring the failure of the transmission path L1 of the active system and the transmission path L2 of the standby system.

When the failure monitoring of the transmission path by the failure monitoring unit 5 is completed, the normal state connection is restored. Therefore, the token acquisition detection circuit 7 of the transmission / reception unit 4 again detects the acquisition of the token frame, It is determined whether a token frame has been acquired (step 109), and if a token frame has been acquired, a token acquisition signal is sent to the switching control unit 6 (step 110). On the other hand, when the switching control unit 6 receives the token acquisition signal sent from the token acquisition detection circuit 7, it sends a standby signal to the transmission temporary stop circuit 8 (step 111). On the other hand, the transmission suspension circuit 8 suspends the transmission of the transmission and reception. Thereafter, the switching control unit 6 further sends a normal state connection signal to the line switching unit 3 and receives the signal, and the line switching unit 3 receives the signal.
Switches from the fault monitoring state connection to the normal state connection (step 112). After the switching to the normal state connection is completed, the switching control unit 6 sends a standby cancel signal to the transmission temporary stop circuit 8 to cancel the temporary stop of the transmission of the transmission / reception unit 4 (step 113). As a result, the fault monitoring state can be returned to the normal state, that is, the communication state using the active transmission line L1.

By the way, when a failure occurs in the working transmission line L1, the status of the protection transmission line L2 is grasped by the failure monitoring, and the protection transmission line is kept in a good state.
The active transmission line L1 can be quickly switched to the standby transmission line. Switching from this active system to the standby system
This can be realized by switching the line switching unit 3. In this case, after the switching from the active system to the standby system, the transmission line of the standby system is grasped as the transmission line of the active system, and the transmission line of the active system is grasped as the transmission line of the standby system. . Therefore, the connection state of the line switching unit 3 is such that in the normal state connection, the terminal a2 and the terminal b1, the terminal a3 and the terminal b2, and the terminal a.
1 and the terminal a4 are respectively connected, and in the fault monitoring state connection, the terminal a3 and the terminal b1, the terminal a4 and the terminal b2, and the terminal a1 and the terminal a2 are respectively connected.

The token acquisition detection circuit 7 and the transmission temporary stop circuit 8 are usually incorporated as an integrated circuit (LSI), and the conventional communication device can also be used as it is as a failure monitoring device.

[0027]

As described above, according to the present invention, there is provided switching means for switching the return connection from the working transmission line through the protection transmission line, and communication is performed using the working transmission line. In the case of performing failure monitoring of the transmission line of the backup system while performing the above, when the token acquisition unit detects and acquires the token frame, the switching control unit causes the switching unit to make a loopback connection, and this loopback connection is performed. After that, a predetermined frame and a token frame are looped back and connected to make a round in the dual ring transmission line, and the failure of the double transmission line is monitored based on the returned predetermined frame. Since the monitoring is performed independently of the device, there is an advantage that the transmission path can be easily monitored with high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a fault monitoring device that is an embodiment of the present invention.

FIG. 2 is a flow chart of fault monitoring control of the fault monitoring device 1.

[Explanation of symbols]

1 Fault monitoring device 2 Input / output unit 3 Line switching unit 4
Transmitter / receiver 5 Fault monitor 6 Switch control unit 7 Token acquisition detection circuit 8 Transmission temporary stop circuit 9 Double ring network L1 Working transmission line L2 Backup transmission line a1 to a4, b1, b2, c1 to c4 terminals

Claims (1)

[Claims] 1. A fault monitoring apparatus for fault monitoring of a dual ring transmission line of a communication system comprising a plurality of stations connected to a dual ring transmission line of an active transmission line and a standby transmission line, Token acquisition means for detecting and acquiring a token frame; switching means for switching a return connection from the working transmission path through the protection transmission path; and after the token acquisition means acquires the token frame, Switching control means for performing switching control of loopback connection to the switching means, and after the loopback connection, transmits a predetermined frame and a token frame to the double ring transmission line, and makes a loop of the loopback transmission lines of the active system and the standby system, And a monitoring means for monitoring a failure of the dual ring transmission line based on the returned predetermined frame. Place