JP2734410B2 - Transmission line switching system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line switching system, and more particularly to a system in which two opposing terminal stations are connected by a working line and a protection line which are redundant lines, and are switched to a protection line when a failure of the working line occurs. The present invention relates to a transmission line switching system.

[0002]

2. Description of the Related Art In a conventional transmission line switching system of this type, when an active line fails, communication is performed by switching to a protection line, thereby improving the reliability of the system.

[0003]

In the above-mentioned conventional transmission line switching system, when the protection line is switched to the protection line when the working line connecting the two opposite terminal stations fails, the protection line returns to a so-called loop state. However, since there is no means for detecting this loop state, transmission line switching control is performed while the protection line is in a loopback state, and as a result, communication becomes impossible. .

Accordingly, the present invention has been made to solve such a conventional disadvantage, and an object of the present invention is to provide a transmission line switching method capable of detecting that a protection line is in a looped state in a folded state. It is to provide a system.

[0005]

According to the present invention, there is provided a transmission line switching system for connecting terminal stations facing each other by two pairs of redundant working and protection lines and controlling switching from a working line to a protection line. there, at the end station, and means for delivering the device individual identification information for identifying individual local end station when switching the line to the protection line has been transmitted from the opposite terminal station via said protection line means for extracting said device individual identification information, and means for comparing the device individual identification information of the extracted device individual identification information and the own terminal station, an alarm issued to fire a warning when the comparison result indicates a coincidence means
And a transmission line switching system characterized by including the following .

[0006]

The device individual identification information capable of individually identifying the terminal station is transmitted using the protection line, and the device individual identification information received from the protection line is compared with the device individual identification information of the own device and matched. If so, it is determined that the protection line is in a loop state.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, a transmission line switching device 1 in one terminal station controls an active system interface unit 2 and a standby system interface unit 3 that provide interfaces to a working transmission line 14 and a protection transmission line 15, respectively, and performs switching control of a working protection. And a switching control unit 4 for performing the switching.

It is assumed that the transmission line switching device of a terminal station (not shown) facing the terminal station having the transmission line switching device 1 has the same configuration as that of FIG.

The active interface unit 2 and the standby interface unit 3 have basically the same configuration, and the configuration of the standby interface unit 3 will be described. The switching control information adding section 6 adds a switching control information element to a transmission signal based on a command from the transmission path switching control section 11 of the switching control section 4 and transmits the transmission signal.

As an example of the transmission line switching method in this case, I
G. TU-T Recommendations 707 to 709, 783, the section overhead (SOH) K
Since the switching control information is communicated with the opposite terminal using the 1 / K2 byte, the switching control information is added to the K1 / K2 byte of the SOH, and the protection transmission line output unit is used. 5 sent out.

Further, in the present invention, a device-specific identifier adding unit 7 is provided, and a device-specific identifier for individually specifying the own terminal station is added thereto.
Is transmitted to the protection transmission line 15 via This identifier is also S
If transmission is performed using the K1 / K2 bytes of the OH and values that are not normally used are assigned to these individual device identifiers, compatibility with conventional communication is ensured.

The signal transmitted from the opposite terminal via the protection line 15 is received by the switching control information recognition unit 9 via the protection line input unit 18, and the switching control information is detected. 4 is transmitted to the transmission path switching control unit 11.

Further, in the present invention, the device individual identifier recognizing unit 10 is provided, and the device individual identifier inserted into the K1 / K2 byte in the SOH of the signal transmitted through the protection line 15 is extracted. Will be detected.

The switching control unit 4 is provided with a device individual identifier comparing unit 12, which compares the identifier of the own device in the device individual identifier adding unit 7 with the identifier transmitted from the backup transmission line 15, The comparison result is reported to the loop state alarm issuing unit 13.

When the comparison result indicates a match, the loop state alarm issuing section 13 determines that the standby transmission line 15 is in a loop state and is abnormal, and issues a switching prohibition command to the transmission line switching control section 11. become.

In the above configuration, the protection system interface unit 3 applies a signal to the protection transmission line 15
The switching control information adding unit 6 and the device individual identifier adding unit 7 add the switching control information and the individual identifier of the own device, respectively, and send them out from the standby transmission line output unit 5 to the standby transmission line 15. Also,
The switching control information recognizing unit 9 and the device individual identifier recognizing unit 10 recognize the switching control information and the device individual identifier, respectively, from the signal input from the standby transmission line 15 to the standby transmission line input unit 8.

The device-specific identifier comparing unit 12 compares the device-specific identifier transmitted to the protection line 15 with the protection identifier of the protection line 15.
Is compared with the device individual identifier input from, and when they match, it is determined that a loop state has occurred, a loop state alarm issuing section 13 issues a loop state alarm 20, and the transmission path switching control section 11 An instruction to prohibit switching is given.

FIG. 2 is a diagram for explaining the operation when the backup transmission line 15 is normal. In a case where the terminal stations 16 and 17 are opposed to each other, assuming that the individual device identifiers of the terminal stations 16 and 17 are A and B, the terminal station 16 receives the device individual identifier B from the terminal station 17 and Compared with the device individual identifier A, it is determined that the state is not a loop state because of mismatch, and a loop state alarm is not issued.

FIG. 3 is a diagram for explaining the operation when the backup transmission line 15 performs loop communication. Before the terminal station 17, the spare transmission line 15 is turned back to form a loop, so that the device individual identifier from the spare transmission line 15 is A, and the comparison result indicates a match. A loop condition alarm will be issued. As a result, line switching is prohibited.

[0021]

As described above, according to the present invention, the return state of the backup transmission path is detected by adding the device-specific identifier to the overhead part of the transmission signal and transmitting the transmission signal to the opposite terminal station. Therefore, it is possible to prevent erroneous switching from occurring.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram at the time of normal operation in the block of FIG. 1;

FIG. 3 is an explanatory diagram at the time of loop communication in the block of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission line switching device 2 active system interface unit 3 standby system interface unit 4 switching control unit 5 standby transmission line output unit 6 switching control information adding unit 7 device individual identifier adding unit 8 standby transmission line input unit 9 switching control information recognition unit 10 Device individual identifier recognizing unit 11 Transmission line switching control unit 12 Device individual identifier comparing unit 13 Loop status alarm issuing unit 14 Working transmission line 15 Standby transmission line 16, 17 Terminal 20 Loop state alarm issuing

Claims (3)

(57) [Claims] The present invention relates to redundant working and
Connected by a preliminary of two sets of lines, the protection line from a working line
A transmission line switching system for controlling switching to, in the end station, and means for delivering the device individual identification information for identifying individual local end station when switching the line to the protection line, from the opposite end station means for extracting said device individual identification information has been sent via the protection channel, and means for comparing the device individual identification information of the extracted device individual identification information and the own terminal station, the comparison result is a match Alarm when showing
A transmission line switching system comprising: an alarm issuing unit that issues an alarm . 2. The alarm issuing means, when the comparison result indicates a match, issues a line switching prohibition command to the protection line.
2. The transmission line switching system according to claim 1, wherein the transmission path switching system outputs the transmission line. 3. The apparatus according to claim 1, wherein the device identification information is inserted in an overhead part of a transmission signal.
Or the transmission line switching system according to 2.