JP2550887B2 - Line switching device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching device for switching a working line and a protection line among a plurality of lines connecting opposite devices.

[0002]

2. Description of the Related Art Generally, in a communication system in which opposing devices are connected by a communication line, one or more spare lines are provided in addition to the working line in order to protect an important line such as an emergency line. Even if an abnormality occurs in the line, communication is possible between the opposite devices without any trouble.

Conventionally, as an opposite switching method for switching a line from a working line to a protection line, there is a system in which switching is performed by only one of the facing devices. That is, in this switching system, the transmitting side sends information to either the working line or the protection line, and the receiving side can receive information from both the working line and the protection line. On the contrary, the transmitting side is configured to send the same information to both the working line and the protection line, and the receiving side to receive the information from one of the lines.

As another conventional opposite switching method, there is also a method of switching lines on both the transmitting side and the receiving side.

In any of the above methods, in the case of a communication system having an upstream signal line and a downstream signal line, switching is performed in order to make the switching states of the upstream signal line and the downstream signal line match. The control signals need to be communicated with each other.

Conventionally, the communication of the switching control signal is performed by providing a dedicated line other than the working line and the protection line. Alternatively, the switching control signal is superimposed on the main signal and is performed via the working line or the protection line.

[0007]

In the conventional opposite switching system, a dedicated line must be provided for transmitting and receiving the switching control signal, and considering the case where this dedicated line is disconnected, reliability and cost are reduced. There is a problem in terms.

Further, the method of superimposing the switching control signal on the main signal has a problem that the switching control signal cannot be transmitted unless there is an empty space (empty bit) in the main signal. Further, even if there is an empty space in the main signal, it takes time to transmit the switching control signal if the number of empty bits per unit time is small. That is, there is a problem that the transmission speed is slow and the switching operation may be delayed.

It is an object of the present invention to provide an opposite switching system which can perform a switching operation reliably and without delay.

[0010]

According to the present invention, a transmission switch for selectively connecting an input terminal to either one of a transmission working line and a transmission protection line, a reception working line and a reception protection line. A receiving switch that selectively connects any one of the lines to an output terminal, and the transmitting switch has the input terminal when a failure occurs in at least one of the transmitting working line and the receiving working line. In the line switching device, wherein the reception switching unit connects the reception standby line to the output terminal,
A switching control signal generator that outputs a switching control signal, and the receiving working line and the receiving protection line are monitored to detect a main signal transmitted through the receiving working line and the receiving protection line. A main signal detector and a switching control signal detector that monitors the receiving working line and the receiving protection line and detects the switching control signal transmitted through the receiving working line and the receiving protection line. And
The transmission switching means connects the input terminal to one of the transmission working line and the transmission protection line, and connects the switching control signal generator to the other, and the main signal detector. Detects that the main signal transmitted via one of the receiving working line and the receiving protection line is disconnected, and the switching control signal detector detects the receiving working line and the receiving protection line. Before when the switching control signal transmitted through the other line of the line is detected and when the main signal detector detects that the line from which the main signal is transmitted is changed to the other line. The transmission switching device and the reception switching device are controlled to connect the input terminal to the other of the transmission working line and the transmission protection line, and to the output terminal to the reception working line. And the reception Line switching device is obtained which is characterized in that so as to connect the other line of the protection line.

Further, according to the present invention, any one of the plurality of transmission lines and the transmission switcher for selectively connecting the input terminal to one of the plurality of transmission lines is selectively output. A reception switch connected to the terminal, and the transmission switch is connected to the input terminal when a failure occurs in at least one of the transmission line connected to the input terminal and the reception line connected to the output terminal. A line switching device in which a terminal is selectively connected to one of the other transmission lines, and the reception switching device selectively connects the output terminal to one of the other reception lines. A switching control signal generator that outputs a switching control signal; a main signal detector that monitors the plurality of reception lines and detects a main signal transmitted through the plurality of reception lines; Monitoring the receiving line of each and transmitting through the multiple receiving lines A switching control signal detector for detecting the incoming switching control signal is provided, and the transmission switching means selectively connects the input terminal to one of the plurality of transmission lines, and All the transmission lines are connected to the switching control signal generator, and when the main signal detector detects that the main signal transmitted via the reception line is disconnected, and the main signal When it is detected that the receiving line to be transmitted is changed to another line, the transmitting switch and the receiving switch are controlled to change the input terminal to another line in accordance with a predetermined rule. In addition to connecting to the transmission line, the switching control signal generator is connected to all the other transmission lines, and the output terminal is connected to the other reception line in accordance with a predetermined rule. A line switching device characterized by It is.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, the line switching devices 11a and 1a are connected to the opposite station A and station B, respectively.
1b are connected to each other, and the line switching devices 11a and 11b are connected to each other by the up and down working lines 12a,
12b and the protection lines 13a and 13b are connected.

The line switching devices 11a and 11b send a main signal to either the working line or the protection line and send a switching control signal to the other line, and a transmission signal switch 14 is provided.
And a switching control signal generator (P
G) 15 and a main signal detector (DET1) for detecting a main signal from the signals received from the working line and the protection line
16 and switching control signal detectors (D) for detecting switching control signals from the signals received from the working line and the protection line, respectively.
ET2) 17, a reception signal switcher 18 for selectively outputting either one of the signals received from the working line and the protection line, and based on the outputs of the main signal detector 16 and the switching control signal detector 17. The transmission signal switching device 14, the switching control signal generator 15, and the reception signal switching device 18 are provided with a switching controller (CONT) 19.

Next, the operation of this line switching device will be described. First, the normal operation will be described. The main signal transmitted from the A station to the B station is the line switching device 1 in the A station.
1a and is divided into two so that it can be sent to both the working line 12a and the protection line 13a. The transmission signal switch 12 uses one of the two main signals divided into the working line 12
At the same time, the switching control signal from the switching control signal generator 15 is transmitted to the protection line 13a.

On the other hand, station B uses the main signal detector 16 and the switching control signal detector 17 to monitor the signals received from the working line 12a and the protection line 13a. Normally, a main signal is sent from the working line 12a and a switching control signal is sent from the protection line 13a, and the switching controller 19 outputs the signal sent from the working line 12a as a reception signal. Received signal switch 18 is switched, working line 12
The transmission signal switching unit 14 is switched so that the main signal from the station B is transmitted to b. The transmission from the B station to the A station is performed in the same manner.

Next, the switching operation will be described. When the transmission signal switch 14 is switched on the station A side, a switching control signal is sent to the working line 12a and a main signal is sent to the protection line 13a. On the B station side, the main signal detector 16 and the switching control signal detector 17 monitor the working line 12a and the protection line 13a, and the switching control signal is sent from the working line 12a and the main signal is sent from the protection line 13a. To detect that Based on this detection result, the switching controller 19 switches the reception signal switch 18 so as to output the signal sent from the protection line 13a as a reception signal, and the protection line 1
The transmission signal switch 14 is switched so that the main signal is transmitted to 2b.

Similarly, at the station A, the main signal detector 16 and the switching control signal detector 17 have the working line 12b and the protection line 13 respectively.
b is monitored, and it is detected that the switching control signal is being sent from the working line 12b and the main signal is being sent from the protection line 13b, and it is confirmed that the switching at station B has been completed.
At the same time, the switching controller 19 switches the reception signal switching device 18 so as to output the signal sent from the protection line 13a as a reception signal, and ends the switching operation.

When any one of the lines is disconnected, this line switching device operates as follows. That is, the working line 12
When a is disconnected, the main signal detector 16 on the working line 12a side at station B cannot detect the main signal. On the other hand, the switching control detector 17 on the protection line 13a side is
Since the switching control signal is detected, the switching controller 19
It recognizes that the working line 12a is disconnected and the protection line 13a is normal. Therefore, the switching controller 19 switches between the transmission signal switching device 14 and the reception signal switching device 18, and performs transmission / reception using the protection lines 13a and 13b. The station A performs the switching operation of its own station by detecting that the station B has switched as described above for the switching operation.

When the protection line 13a is disconnected, B
Although the station side detects that, the switching operation is not performed, and the notification or the like is performed. If the working line 12b is disconnected,
Also, when the protection line 13b is disconnected, the same operation as described above is performed. Also, the switching control signal is used to determine whether the backup line is normal,
It can be easily inferred that the switching operation can be performed without the switching control signal generator 15.

Thus, in the line switching device of this embodiment,
When a line disconnection occurs, it is immediately detected by the line switching device on the opposite station side, and line switching is performed without delay.

In the above description, the line switching device having one uplink and one downlink protection line has been described, but the same applies to a line switching device that selects one of N lines and transmits a main signal. The present invention can be applied. FIG. 2 shows such a line switching device. As shown in FIG. 2, this line switching device has N transmission signal switching devices 14 and distributes input signals so that a main signal is input to each of them.
One of the N transmission signal switches 14 is switched to send the main signal, and the other N-1 transmission signal switches 14 are switched to send the switching control signal. The signals sent from the plurality of lines are detected by the main signal detector 16 and the switching signal detector 17. Here, the main signal detector 16 and the switching signal detector 17
Shall be able to detect the presence or absence of signals individually for all N lines. Further, the reception signal switch 18 is a 1 / N selector (SEL) that can selectively select one of the N lines, and the switching controller 19 switches the N transmission signal switches 14 and the reception signals. The control unit 18 is controlled to switch and control one line as a working line and the other as a protection line.

In this line switching device, it is necessary to instruct the line switching device in advance which of the N lines should be used and which line should be switched when the working line is disconnected. Then, the switching operation similar to that of the line switching device of FIG. 1 becomes possible.

[0023]

According to the present invention, it is not necessary to provide a dedicated line for transmitting the switching control signal, so that the structure can be simplified and the cost can be reduced and the reliability can be secured. Further, the occurrence of a failure can be detected also in the protection line, so that the reliability is further improved. further,
The switching operation can be performed without delay because it is not restricted by the main signal and does not depend on the transmission speed of the main signal.

[Brief description of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

[Explanation of symbols]

 11a, 11b Line switching device 12a Uplink working line 12b Downlink working line 13a, 13b Backup line 14 Transmission signal switching device 15 Switching control signal generator (PG) 16 Main signal detector (DET1) 17 Switching control signal detector (DET2) 18 Received signal switch 19 Switch controller (CONT)

Claims (2)

(57) [Claims] 1. A transmission switcher for selectively connecting an input terminal to either one of a transmission working line and a transmission protection line, and selectively outputs one of a reception working line and a reception protection line. A reception switcher connected to the terminal, the transmission switcher connects the input terminal to the transmission standby line when a failure occurs in at least one of the transmission working line and the reception working line, In a line switching device in which the reception switching device connects the reception protection line to the output terminal, a switching control signal generator that outputs a switching control signal, the reception working line and the reception protection line are provided. A main signal detector for monitoring and detecting a main signal transmitted through the receiving working line and the receiving protection line, and the receiving working line and the receiving protection line for monitoring the receiving working line A switching control signal detector for detecting the switching control signal transmitted via a line and the reception protection line, wherein the transmission switching means is one of the transmission working line and the transmission protection line. The input terminal is connected to either one and the switching control signal generator is connected to the other, and the main signal detector transmits through one of the receiving working line and the receiving protection line. And when the switching control signal detector detects the disconnection of the main signal and detects the switching control signal transmitted through the other line of the receiving working line and the receiving protection line, and When the main signal detector detects that the line from which the main signal is transmitted is changed to the other line, it controls the transmission switch and the reception switch to set the input terminal to the Current for transmission A line is connected to the other line of the transmission protection line, and the other of the reception working line and the reception protection line is connected to the output terminal. Line switching device. 2. A transmission switcher for selectively connecting an input terminal to one of a plurality of transmission lines, and a reception switch for selectively connecting any one of a plurality of reception lines to an output terminal. And a transmission line connected to the input terminal and a reception line connected to the output terminal when a failure occurs, the transmission switcher switches the input terminal to another transmission line. In the line switching device, which is selectively connected to one of the lines and the reception switch selectively connects the output terminal to one of the other receiving lines, A switching control signal generator for outputting, a main signal detector for monitoring the plurality of receiving lines and detecting a main signal transmitted through the plurality of receiving lines, and a monitoring for the plurality of receiving lines The switching control transmitted via the plurality of receiving lines A switching control signal detector for detecting a signal is provided, and the transmission switching means selectively connects the input terminal to one of the plurality of transmission lines,
All other transmission lines are connected to the switching control signal generator, and when the main signal detector detects that the main signal transmitted via the reception line is disconnected, and When it is detected that the receiving line from which the main signal is transmitted is changed to another line, the transmission switching device and the reception switching device are controlled to control the input terminal according to a predetermined rule. While connecting to another transmission line,
A line switching device, wherein the switching control signal generator is connected to all other transmission lines, and the reception terminals are connected to the output terminals in accordance with a predetermined rule. .