JPH10336160A - Transmission line switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transmission line switching device whose operation status does not change in a path switching section on a subsequent stage. SOLUTION: Selectors 30 and 31 perform switching in a transmission line switching section 1. In a receiving part in a path switching section 2, phase adjusting circuits 50 and 51 perform phase adjustment, path alarm detecting circuits 60 and 61 detect path alarm and selectors 80 and 81 on a subsequent stage perform path switching. Buffer memory 70 and 71 are provided not to transmit a wrong main signal to a lower part until the selectors 80 and 81 operate after detecting path alarm. Also, a receiving terminal transfers, to a sending terminal, system selection information 40 and 41 that indicate which is for a current system. Referring to the information 40 and 41, changeover between automatic or manual switching in the section 1 is performed so that a selector of a system always connected to a current system path operates, and then a selector connected to a spare system operates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an APS (Automatic
The present invention relates to a transmission path switching device in a transmission system in which a transmission path switching section for switching between transmission paths by a protection switch and a path switching section are connected.

[0002]

2. Description of the Related Art Conventionally, a transmission line switching device, for example,
It is configured in a transmission system having a redundant configuration of two systems, system 0 and system 1. In the transmission system of Conventional Example 1 having this configuration, when switching between both transmission paths is performed by APS, there are usually two selectors for realizing the transmission path switching, and the same system must always be selected. Originally, it is desirable that this selector be controlled simultaneously.

[0003] Selectors are provided at different points in the 0-system and the 1-system, and the processing of the APS is very complicated. For this reason, the control of the selector is fixedly and sequentially performed from the selector of any system by the microprocessor as the control means. For example, there is a processing procedure in which the system 0 is the first and the system 1 is the later.

[0004] In order to improve the reliability of the transmission system having the above-described configuration, a signal between the paths having the redundant configuration of the 0 system and the 1 system is affected even if a path alarm is detected at the receiving end. It is necessary to provide a path switching system that performs switching without interruption without any interruption.

[0005] The "redundant system switching control system" of Japanese Patent Laid-Open No. 6-61985 of the prior art 2 employs a system 0 system and a system 1 system.
A switching information control unit is provided to mutually transfer status information such as switching control status, and to transmit status information of the own system device, status information of another system device, and other devices connected to the 0 system device and the 1 system device. A control signal for system switching to another device is transmitted based on the status information such as the alarm signal. According to this configuration, there is no need for a dedicated system switching control unit as in the related art, and only a few talk signal lines need to be provided between the system 0 device and the system 1 device. It has the advantage of a simple configuration.

[0006]

However, in the path switching system having the configuration according to each of the above-described conventional examples, a transmission line switching section having the above-described transmission path switching system by APS switching is provided at a stage preceding the path switching section. When a selector for switching the section operates, an error occurs in the signal. For this purpose, FIG.
As shown in (1), there is a problem that the operation state may change in the subsequent path switching section with the switching of the transmission path switching section.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmission line switching apparatus in which the operation state does not change in a subsequent path switching section even when there is a transmission path switching section having a transmission path switching system by APS switching.

[0008]

In order to achieve the above object, a transmission line switching device according to the present invention provides a path alarm which is detected at a receiving end between paths having a redundant configuration of two systems, system 0 and system 1. Is a transmission path switching device in which a path switching section that performs switching without interruption by instantaneous interruption and a transmission path switching section that performs switching between the 0-system and 1-system transmission paths by APS at the previous stage are connected. A selector connected to the path switching section, a selector connected to the transmission path switching section, a buffer memory provided after the path alarm detection point, and System operation control means for constantly monitoring the operation state of the path switching section and operating from the selector connected to the working path, and a buffer memory for preventing the signal from being affected. To switch before the signal from accidentally re is read, it is characterized in that to prevent malfunction of the operational state of at a later stage of the path switching section by the switching of the transmission path switching zone.

The switching in the transmission path switching section may include both automatic switching performed upon detection of an alarm and manual switching.

Further, the above selector recovers the alarm of the active path by the operation of the first selector,
It is preferable to recover the alarm of the standby system by the second operation of the selector.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a transmission line switching apparatus according to the present invention. 1 to 3 show an embodiment of a transmission line switching device according to the present invention. FIG. 1 is a block diagram of a transmission system to which an embodiment of a transmission line switching device according to the present invention is applied. FIG. 2 is a timing chart showing an operation example of automatic switching, and FIG. 3 is a timing chart showing an operation example of manual switching.

In the transmission system shown in FIG. 1, a transmission line switching section 1 having a redundant configuration of system 0 and system 1 and a path switching section 2 having a redundant configuration of system 0 and system 1 are connected by a transmission line. It is configured.

In the transmission line switching section 1 of the transmission system having the above configuration, each of the system 0 and system 1 includes an IF and a selector 3.
0/31, and mutual signals are input to the selector 30/31.

In the path switching section 2, in each of the 0 system / 1 system, an IF, a phase matching circuit 50/51, a buffer memory 70/71, and a selector 80/81 are connected in series. Further, the buffer memory 70
A path alarm detection circuit 60/61 is connected in parallel before / 71. Incidentally, mutual signals are input to the selectors 30/31.

Transmission In the configuration of the present system, it is assumed that the selector 80/81 includes a system operation control unit and controls the overall operation as a transmission line switching device.

In the transmission system having the above configuration, the switching of the transmission line switching section 1 is performed by the selectors 30 and 31. From the signals of both system 0 and system 1, based on the phase information added at the transmitting end on the opposite side,
Phase matching circuits 50, 5 at the receiving end in path switching section 2
1 is used to perform phase matching. Then, the path alarm detection circuit 6
Based on the path alarms detected at 0 and 61, the subsequent selectors 80 and 81 perform path switching.

After detecting the path alarm, the selectors 80, 8
Buffer memories 70 and 71 are provided in order to prevent an erroneous main signal from being transmitted to the lower order during the time until the first operation. Also, system selection information 40, 41 indicating which system is selected as the active system is transmitted from the receiving end of the path switching section 2 to the transmitting end of the transmission path switching section 1 using the path in the opposite direction. Forward.

As shown in the timing diagrams of FIGS. 2 and 3,
When automatic switching is performed by detecting an alarm in the transmission path switching section 1 and when manual switching is performed, the selector of the system that is always connected to the active system path is referred to by referring to the system selection information 40 and 41 described above. And then operate the selector connected to the standby system.

When an alarm is detected in the active system in the transmission path switching section 1 and automatic switching is performed, in the subsequent path switching section 2, an alarm is detected in the paths of both systems. Therefore, the alarm of the active path is recovered by the first operation of the selector, and the alarm of the standby system is recovered by the second operation of the selector. Therefore, no path switching occurs in the path switching section 2.

Similarly, when performing manual switching, similarly, an error occurs in the working path due to the operation of the first selector, switches to the protection path, and then an error occurs due to the operation of the other selector. Return to.

According to the above operation procedure, switching is performed twice in total. However, these path switchings are instantaneous interruptions, and the operation state of the path switching section 2 does not change.

An example of the operation will be described below with reference to FIGS. FIG. 1 has a redundant configuration of 0 system and 1 system,
It has a transmission line switching section 1 in which switching between both transmission lines is performed by APS, and a redundant configuration of system 0 and system 1 for improving reliability. This configuration shows a transmission system to which a path switching section 2 for switching between both paths without an instantaneous interruption without affecting a signal even when a path alarm is detected is connected. In this transmission system,
Switching of the transmission line switching section 1 is performed by the selectors 30 and 3
1 and the signals of the selected system are divided into 2 of the 0 system and 1 system.
The signals are transmitted to the path switching section 2 in the same phase as the system signals.

The two selectors 30 and 31 are controlled so as to always select the same system. However, these selectors are provided at different locations, and further, the APS
Is very complicated. For this reason, control is sequentially performed within a few msec by the microprocessor. The phase matching circuits 50 and 51 at the receiving end of the path switching section 2 detect the phase information added at the transmitting end on the opposite side from both the signals of the system 0 and the system 1 and perform phase matching. The transmission delay time difference due to the path length difference of the first system is absorbed. Thereafter, path alarm detection circuits 60 and 61 detect a path alarm from the signal.

In accordance with the path alarm detected by the path alarm detection circuits 60 and 61, the selectors 80 and 81 at the subsequent stage perform path switching. Further, the receiving end of the path switching section 2 is provided with buffer memories 70 and 71 for preventing an erroneous signal from being transmitted to the lower order during the time from the detection of the path alarm to the operation of the selectors 80 and 81. Also,
System selection information 40, 41 indicating which system is selected as the active system at the receiving end is transferred to the transmitting end on the opposite side using a path in the opposite direction. This makes it possible to always grasp the operation state of the path switching section 2 in the transmission path switching section 1.

First, as shown in FIG. 2, when a transmission line alarm is detected in the active system of the transmission line switching section 1,
In the path switching section 2 at the subsequent stage, a path alarm is simultaneously detected in both paths. Therefore, no path switching is performed. FIG. 2 shows an example in which the system 0 in the path switching section 2 is the active system and the system 1 is the standby system.

Here, when switching the transmission line switching section 1 by operating the selectors 30 and 31, the system selection information 40 and 41 among the selectors 30 and 31 that realize the transmission line switching are referred to. In this case, the operation state of the receiving end of the path switching section 2 is always connected to the working path, that is, in FIG. By the operation of the selector 30, the path alarm of the system 0 which is the working path is first recovered, and thereafter,
The selector 31 connected to the standby system is operated. As a result, the path alarm of the standby path is recovered, so that the switching of the path switching section 2 does not occur, and the operation state does not change.

Similarly, when the transmission path is switched manually, the selectors are sequentially operated from the selector connected to the working path. As shown in FIG. 3, an error occurs in the active path due to the operation of the selector 30 first connected to the active path (in FIG. 3, the 0-system path is the active path), and the path is switched to the standby path. Switching is performed without interruption.

Next, the other selector 31 is operated. In this case, too, an error occurs in the path, and the system switches back to the previous system.
This switching is also uninterrupted. That is, the path switching is performed twice in total, but this switching is instantaneous interruption switching, and the operation state of the path switching section 2 finally returns to the previous state.

By performing the switching of the transmission path switching section 1 according to the above procedure, it is possible to prevent a change in the operation state in the path switching section 2 connected at the subsequent stage.

The transmission path switching apparatus of the present invention always operates the path switching section at the subsequent stage when the automatic switching is performed by detecting an alarm in the transmission path switching section and when the switching is performed manually. It monitors and always operates from the selector connected to the working path. By performing the switching of the transmission path switching section by this method, it is possible to prevent a change in the operation state in the subsequent path switching section.

According to the present invention, even when a path alarm is detected at the receiving end, a path switching section for realizing switching without instantaneous interruption without affecting a signal and a transmission for switching between transmission paths by APS. In a transmission system to which a path switching section is connected, it is possible to prevent a change in an operation state of a subsequent path switching section caused by switching of a preceding transmission path section.

Although the above embodiment is an example of a preferred embodiment of the present invention, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

[0033]

As is apparent from the above description, the transmission line switching apparatus of the present invention monitors the operation state of the subsequent path switching section when switching the transmission path switching section, and always monitors the working path. , It is possible to prevent a change in the operation state in the path switching section.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission system to which an embodiment of a transmission line switching device according to the present invention is applied.

FIG. 2 is a timing chart showing an operation example of automatic switching according to the present invention.

FIG. 3 is a timing chart showing an operation example of manual switching according to the present invention.

FIG. 4 is a timing chart for explaining a conventional operation example.

[Explanation of symbols]

 1 Transmission line switching section 2 Path switching section 30, 31 Selector 40, 41 System selection information 50, 51 Phase matching circuit 60, 61 Path alarm detection circuit 70, 71 Buffer memory 80, 81 Selector

Claims (3)

[Claims] 1. A path switching section in which a path between two paths having a redundant configuration of a system 0 and a system 1 is switched without any instantaneous interruption by using a path alarm detected at a receiving end as a trigger,
In a transmission line switching apparatus in which a transmission line switching section for switching between a system 0 and a system 1 transmission line by an APS is connected in a preceding stage, a selector connected to the path switching section, and a connection to the transmission line switching section The selector, the buffer memory provided at the subsequent stage of the detection point of the path alarm, and when performing switching in the transmission line switching section, constantly monitor the operation state of the subsequent path switching section, the active path A system operation control means for operating from a connected selector, wherein the switching is performed before an erroneous signal is read from the buffer memory so as not to affect a signal, and a subsequent stage is performed by switching the transmission line switching section. A transmission line switching device characterized in that a malfunction of an operation state in a path switching section is prevented. 2. The transmission line switching device according to claim 1, wherein the switching in the transmission line switching section includes both automatic switching performed by detecting the path alarm and manual switching. 3. The selector according to claim 1, wherein the operation of the first selector recovers the alarm of the active path by the operation of the first selector, and recovers the alarm of the standby system by the operation of the second selector. The transmission path switching device according to the above.