JPH0451723A - Line changeover system - Google Patents

Abstract

PURPOSE:To quickly select a standby line and to repair a faulty active line readily on the occurrence of a fault in the active line by monitoring the standby line with a test signal normally, keeping the standby line to be the best at all times and monitoring the characteristic of the faulty active line. CONSTITUTION:A 2nd switch of a line changeover device 1 connects points 11, 14 of a standby line, and a 1st switch of a line changeover device 2 connects points 21, 24. Thus, the standby line 32 is in loopback state at the line changeover device 1, and a test signal sent from a test signal generating circuit 25 of the line changeover device 2 to the standby line 32 is returned to a test signal detection circuit 26. The test signal detection circuit 26 discriminates the propriety of the characteristic and raises an alarm in the case of a defective characteristic. When the active line 31 is faulty, the switch of each line changeover device is thrown as shown in figure 2, and the test signal generating circuit 25 and the test signal detection circuit 26 are thrown to the faulty active line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a line switching system used in a redundant communication network.

[Conventional technology]

In a line switching system equipped with a line switching device at both ends of the line for switching between a working line and a protection line in a redundant communication network, monitoring of the working line and protection line has conventionally been carried out using the following methods:
As shown in FIG. 3, a monitoring circuit 34 for each transmission line section, which is installed in a line termination device 33 connected to each line, performs, for example, input pulse disconnection and out-of-synchronization monitoring for each section. It is being said. On the other hand, when each line termination device f33 detects a fault in the working line 31, the line switching device la,
2a respectively switch from the working line 31 to the protection line 32.

[Problem to be solved by the invention]

With the conventional monitoring circuit described above, it is not possible to check characteristics such as code errors and S/N, so if the working line becomes faulty and is switched to the protection line, the protection line is used due to poor line characteristics. It may prove impossible. For this reason, there is a drawback that a large amount of time must be spent until the failure is recovered.

An object of the present invention is to provide a line switching system capable of quickly restoring the line using a backup line when a working line fails, and quickly repairing the failed working line.

[Means to solve the problem]

The line switching system of the present invention includes a line switching device at both ends of a line for switching between a working line and a protection line in a redundant communication network, and a sending unit for sending a test signal to one end of the protection line. and one line switching device comprising: detecting means for receiving the test signal returned to the other end of the protection line and determining the line state; and first switching means for switching the line for transmitting and receiving the test signal; , the other line comprising a second switching means for switching a line for transmitting and receiving the test signal in correspondence with the first switching means, and a means provided in the second switching means for returning the test signal. It consists of a switching device.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1 showing an embodiment of the present invention, the line switching system is composed of line switching devices 1 and 2 connected at both ends via a working line 31 and a protection line 32. A test signal generation circuit 25 that sends a test signal to one end of the protection line 32, a test signal detection circuit 26 that receives the test signal returned to the other end of the protection line 32 and determines the line state, and a switching connection point 21. a first switch that switches the line for transmitting and receiving test signals; and a switching connection point 22.
24 and a third switch for switching between the working line 31 and the protection line 32.

The line switching device W1 includes a second switch that switches the line for transmitting and receiving the test signal in correspondence with the first switch, and a loop 1 back switch that is provided on the second switch and has a switching connection point 11 and returns the test signal. It includes a circuit 15 and a fourth switch that has switching connection points 12 to 14 and switches between a working line 31 and a protection line 32.

The operation will be explained below.Normally, since the working line 31 is used, the fourth switch of the line switching device N1 is set to 12 and 13.
The third switch of the line switching device W2 connects 22 and 23. At this time, on the protection line side, 11 and 14 are connected by the second switch of the line switching device W1, and 21 and 24 are connected by the first switch of the line switching device N2. As a result, the protection line 32 enters a loopback state in the line switching system, and the test signal sent from the test signal generation circuit 25 of the line switching device 2 to the protection line 32 returns to the test signal detection circuit 26. This test signal detection circuit 26 determines whether the characteristics are good or bad, and if it is defective, an alarm is issued. As a result, the maintenance person repairs the backup @ line 32 and keeps the backup line in a normal state at all times.

When a failure occurs in the working line 31, the switches of each line switching device are switched as shown in FIG. 2, and the test signal generation circuit 25 and test signal detection circuit 26 are connected to the failed working line. be done. This allows the maintenance person to immediately know the characteristics of the faulty working line.

〔Effect of the invention〕

As explained above, the present invention constantly monitors the protection line out of the working line and protection line in a redundant communication network using test signals, maintains the protection line in the best condition at all times, and detects a fault when the working line fails. The configuration allows for monitoring of the characteristics of the working line, so in the event of a working line failure,
With the backup line, it is possible to quickly restore the line and also quickly repair the faulty working line.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of the present invention, and FIG.
FIG. 3 is a diagram illustrating a conventional line switching system. 1. la, 2.2a... Line switching device, 11~
14.21-24...Switching connection point, 15...
... Loopback circuit, 25 ... Test signal generation circuit, 26 ... Test signal detection circuit, 31 ...
...working line, 32... protection line, 33.
...Line termination device, 34...Monitoring circuit.

Claims (1)

[Scope of Claims] In a line switching system comprising line switching devices at both ends of a line for switching between a working line and a protection line in a redundant communication network, a sending means for sending a test signal to one end of the protection line; one line switching device comprising: a detection unit that receives the test signal returned to the other end of the protection line and determines the line state; and a first switching unit that switches the line for transmitting and receiving the test signal; The other line switching device includes a second switching means for switching a line for transmitting and receiving a test signal in correspondence with the first switching means, and a means for returning the test signal provided in the second switching means. A line switching system characterized by comprising: