JPS6052124A - Route switching control system - Google Patents

Abstract

PURPOSE:To attain ease of switching control between an active system and a spare system in a two-way transmission line of two systems by conducting the switching from the active system to the spare system even at other terminal station with simple operation when one terminal station conducts the switching from the active system to the spare system. CONSTITUTION:If a fault occurs in an active system transmission circuit 11 or a transmission line 15 from a terminal station A to a terminal station B, a control section 25 of the terminal station B supervises a reception output signal level of an active system reception circuit 32 via a signal line 26 and detects that the level is decreased to a prescribed value or below. Then a switching signal is outputted to a signal line 28 and a switching circuit 24 switches a reception circuit to receive a reception output signal of a spare system reception circuit 34. The control section 25 transmits a temporary interrupting signal to a temorary interrupting circuit 23 at the same time so as to interrupt temporarily the transmission signal to an active transmission circuit 31. Since the reception output signal of an active reception circuit 12 is interrupted temporarily at the terminal station A, the switching circuit 4 changes the reception circuit from the circuit 12 of the active system to the circuit 14 of the spare system. Further, even after the switching from the active system to the spare system, a transmission signal is transmitted to the circuits 11 and 31.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a route for controlling switching between the working system and the protection system in a transmission system equipped with two bidirectional transmission lines, the working system and the protection system. This relates to a switching control method.

Conventional technology and problems A transmission system has been adopted that improves reliability by providing two bidirectional transmission lines, one for the working system and the other for the protection system, and switching to the protection system when a failure occurs in the working system. . For example, as shown in FIG. 1, there is a transmission line N1 in the A-B direction between terminal station A and terminal station B, and a transmission line N2 in the B-A direction.
A working system transmission line is configured by the A-B direction transmission line E1 and a B-+A power direction transmission M&E2, and a protection system transmission line is configured by the working system transmission line Nl or the working system transmission line at the terminal station A. If a failure occurs in the transmission circuit of the system, the received signal level at terminal station B will drop, so terminal station B will detect the drop in the received signal level and switch to the backup transmission line E1 to continue receiving. do. In that case, the fault information from terminal station B is transmitted to terminal station A, and terminal station A switches the working transmission line N2 to the protection transmission line E2, receives the signal from terminal station B, and receives the signal from terminal station B. System transmission line N1. From N2 to backup transmission lines El, E2-. A common method is to switch between the two.

In such a conventional switching control method, in order to confirm that the fault in the previously active transmission line N1 has been recovered, it is necessary to is disconnected, so input a test signal to this transmitting circuit, transmit the test signal to terminal B via transmission line N1, and check whether the receiving circuit of terminal B can normally receive the test signal. I needed to check. The same applies to the case where a failure occurs in the transmission line N2 from the terminal station B to the terminal station A. As described above, conventional methods have the drawback that failure recovery operations are complicated. In addition, it was necessary to switch the route from the active system to the protection α1 system at one terminal station, and to transmit failure information for switching from the active system to the protection system to the other terminal station.

Purpose of the Invention The present invention provides for, when one terminal station switches from the working system to the backup system, the other terminal station also switches from the working system to the backup system with a simple operation; The purpose of this is to simplify the operation at the time of failure recovery by continuing to send out a transmission signal from the transmission circuit that was in use even after switching to the standby system.

Structure of the Invention The present invention provides that each bidirectional transmission path includes a working transmitting/receiving circuit and a standby transmitting/receiving circuit, and one of the transmission signals branched by a branch circuit is manually transmitted to the working transmitting circuit via a temporary cutoff circuit. and has a configuration in which the other of the transmission signals is input to a standby transmission circuit, and a switching circuit switches the reception output signals of the working reception circuit and the protection reception circuit, and the reception by the working reception circuit in one direction is performed. Upon detecting that the output signal level has fallen below a predetermined value, the switching circuit switches and outputs the received output signal of the standby system receiving circuit, and the temporary cutoff circuit switches the received output signal to the active system transmitting circuit in the other direction. By temporarily cutting off the transmission signal in the other direction, the system switches to the standby system receiving circuit in the other direction as well, and thereafter continues sending out the transmission signal #1 by each working system transmission circuit. Examples will be described in detail below.

Embodiment of the invention FIG. 2 is an ivy diagram showing the main parts of an embodiment of the invention.
1.21 is a switching control circuit, 2.22 is a branch circuit, 3.2
3 is a temporary cutoff circuit, 4 and 24 are switching circuits, 5.25 is a control i1% that detects the reception output signal level, generates a temporary AI'li signal, and generates a switching signal, etc.; 6 and 26 are reception outputs. Signal lines 7 and 27 are for detecting the signal level, signal lines 7 and 27 are for outputting a temporary cutoff signal, and signal lines 8 and 28 are for outputting a switching signal. In addition, 11 and 31 are active transmission circuits, 1
2. 14.34 is a protection receiving circuit, 15 and 16 are active transmission lines, and 17.18 is a protection transmission line.

When performing optical signal transmission, each transmission line 15 to 18 is constituted by an optical fiber, and the transmission circuits 11, 31, 13, 33
is equipped with an electro-optical converter, and also includes receiving circuits 12.32, 14,
3.4 is equipped with a photoelectric converter. Further, the transmission signal is branched by a branch circuit 2.22, one of which is input to the active transmission circuit 11.31 via the temporary cutoff circuits 3 and 23, and the other to the protection transmission circuit 13.33. Further, the reception output signal of the active system reception circuit 12.32 and the reception output signal of the standby system reception circuit 14.34 are switched and outputted by a switching circuit 4.24.

For example, if a failure occurs in the active transmission circuit 11 or transmission line 15 from terminal station A to terminal station B, the control unit 25 of terminal station B will output the received signal from the active receiving circuit 32 via the signal line 26. Since the signal level is monitored, it is detected that the received output signal level has fallen below a predetermined value, and the signal line 2B is
Outputs a J switching signal, and uses the switching signal to switch the switching circuit 2.
4 is switched to the received output signal of the backup system receiving circuit 34. In addition, in synchronization with the switching, the control section 25 outputs a signal I.
! A temporary cutoff signal is output to 27, and the temporary cutoff circuit 23 temporarily cuts off the transmission signal to the active transmission circuit 31.

At the terminal station A, the received output signal of the active system receiving circuit 12 is temporarily cut off, so the control unit 5, which monitors the received output signal level via the signal line 6, detects a failure in the active system transmission line 16. Then, a switching signal is output to the signal line 8. As a result, the switching circuit 4 switches from the working receiving circuit 12 to the receiving output signal of the protection receiving circuit 14. In that case as well, a temporary cutoff signal is output to the signal line 7, but since the switching from the active receiving circuit 32 to the standby receiving circuit 34 has been performed at the terminal station B, the operation caused by the temporary cutting off of the transmission signal is It becomes irrelevant.

Through the above-described operation, the working transmission line is switched to the protection transmission line, and even after switching, the working transmission circuit 11.
Since the transmission signal is input to 31, if the working transmission circuit 11.31 and the working transmission line 15.16 are normal, the working receiving circuit 12.32 will output the reception output signal. , it is possible to easily identify whether the active system has been restored or not. When the active system has been restored in this manner, switching control from the standby system to the active system can be performed by manual operation or the like using well-known means.

The same applies to the case where a failure occurs in the active transmitting circuit 31 or the active transmission line 16 of the terminal station B, and the control section 5 of the terminal station A monitors the received output signal level of the active receiving circuit 12 and adjusts it to a predetermined level. It detects that the power has fallen below the level below and performs switching control to the standby system in the same manner as described above. Also, active system receiving circuit 1
Even in the case of a failure of 2.32, the occurrence of the failure can be detected by monitoring the level of the received output signal, and switching to the backup system can be performed.

As described in detail, the present invention inputs one of the transmission signals branched by the branch/circuit 2.22 to the active transmission circuit 11.31 via the temporary cutoff circuit 3.23, and The other side of the signal is input to the protection transmitting circuit 13.33, and the receiving output signal of the working receiving circuit 12.32 and the protecting receiving circuit 14.34 is switched by the switching circuit 4.24. The working system receiving circuit 12.32 due to disconnection, etc.
When it is detected that the reception output signal level of
The transmission signal input to the active transmission circuit 11゜3-1 is temporarily cut off, and the terminal station on the receiving side of the transmission signal detects a decrease in the received output signal level, and the switching from the active system to the backup system is performed. By temporarily blocking the input of the transmission signal to the active transmission circuit 11.31, it can be used as an instruction signal to the other terminal station to switch to the protection system, and the other terminal station can automatically switch to the standby system. It is possible to switch to the standby system at any time. Also, even after switching from the active system to the backup system, the transmitting signal is input to the active system transmitting circuit 11.31, so if the fault has been recovered, the receiving circuit at the other terminal station will receive the signal. You will be able to do that. Therefore, there is an advantage that recovery can be detected without sending a test signal.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a transmission system having a bidirectional transmission path of a working system and a protection system, and FIG. 2 is a block diagram of a main part of an embodiment of the present invention. A and B are terminal stations, 1.21 is a switching control circuit, 2°22 is a branch circuit, 3.23 is a temporary cutoff circuit, 4°24 is a switching circuit, 5.25 is a control unit, 6 and 26 are reception outputs Signal line for detecting the signal level, 7.27 is a signal line for outputting a temporary cutoff signal, 8.28 is a signal line for outputting a switching signal, 11
．． 31 is a working system transmission circuit, 12.32 is a working system receiving circuit, 13.33 is a protection system transmission circuit, 14.34 is a protection system receiving circuit, 15.16 is a working system transmission line, 17.18 is a protection system transmission It is a road. Patent applicant: Fujitsu Ltd. Representative Patent Attorney Shoji Aitani Representative Patent Attorney Hiroshi Watanabe −

Claims (1)

[Claims] Each of the bidirectional transmission lines includes a working transmitting/receiving circuit and a standby transmitting/receiving circuit, and one of the transmitted signals branched by the branch circuit is inputted to the working transmitting circuit via a temporary cutoff circuit, and the transmitted signal is The other side is input to a standby system transmitting circuit, and the receiving output signal between the working system receiving circuit and the standby system receiving circuit is switched by a switching circuit, and the reception output signal level of the working system receiving circuit in one direction is a predetermined value. When it is detected that the signal has decreased to below, the reception output signal of the standby system reception circuit is switched and outputted by the radiation switching circuit, and the transmission signal inputted to the active system transmission circuit in the other direction is temporarily shut off by the temporary cutoff circuit. A route switching control method characterized in that by doing so, the other direction is also switched to the standby system receiving circuit, and thereafter each working system transmitting circuit continues to send out a transmission signal.