JPH0787037A - Monitoring method of transmission terminal station - Google Patents

Abstract

(57) [Abstract] [Purpose] Economical monitoring capable of transmitting maintenance signals even in the event of a transmission line failure in a transmission terminal station monitoring method for a data transmission system that transmits main signals and maintenance signals on the same transmission line. Get the scheme. [Configuration] When there are two or more combinations of transmission terminal stations in which a pair of transmission terminal stations are connected via a transmission path between two stations, the transmission terminal stations of each station are connected by a maintenance signal line, When a failure occurs in a transmission path of a combination between any of the transmission terminal stations, the maintenance signal can be transmitted through the combination of the other transmission terminal stations in which no failure has occurred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring system for a transmission terminal station in a data transmission system.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration example of a data transmission system using an optical fiber cable.
In the figure, 1 to 4 are transmission terminal stations, and 5 is an optical fiber cable. The data transmission system shown in FIG. 4 is provided between the two left and right stations (A station and B station) via the optical fiber cable 5.
Station), two or more pairs of transmission terminal stations are arranged in parallel (in the embodiment, there are two transmission terminal stations 1 and 3 for station A and transmission terminals 2 and 4 for station B) for convenience of explanation. The structure is shown between the transmission terminal station 1 and the transmission terminal station 2, and between the transmission terminal station 3 and the transmission terminal station 4.
2 shows a configuration in which data is mutually transmitted and received.

FIG. 5 is a block diagram showing a pair of structures of a conventional transmission terminal station 1 and a conventional transmission terminal station 2. As shown in the figure, each transmitting terminal has a transmitting / receiving unit 10 for transmitting / receiving a main signal and a maintenance unit 2 for transmitting / receiving a maintenance signal.
0 and are built in.

Next, the operation will be described. The main data signal a input to the transmission terminal station 1 is input to the input interface circuit 11 of the transmission / reception unit 10A, modulated into a transmission code by the code conversion circuit 12, and converted into an optical signal by the electrical / optical conversion circuit 13. It is transmitted to the transmission terminal station 2 via the optical fiber cable 5. In the transmission terminal station 2, the transmitted optical signal is converted into an electric signal by the optical / electrical conversion circuit 14, the transmission code is demodulated into a data signal by the code demodulation circuit 15, and the main data signal a is output from the output interface circuit 16. Output.
The main data signal b transmitted from the transmission terminal station 2 is also transmitted to the transmission terminal station 1 via the same path and is output.

Further, in this type of data transmission system,
When a failure occurs, the optical fiber cable 5 also sends and receives a maintenance signal because it is necessary to notify it to a manned station. For example, the maintenance signal is sent and received with respect to the main signal by a code violation rule or a spare bit. The maintenance signal is transmitted and received using the maintenance unit 20 by superimposing the maintenance signal on the main signal using the method of adding the maintenance signal. That is, referring to FIG. 5, the maintenance signal of the own transmission terminal station 1 is input from an external device (not shown) to the maintenance signal input interface circuit 21 of the maintenance unit 20A of the transmission terminal station 1 and the main signal is converted by the code conversion circuit 12. To the transmission terminal station 2 via the optical fiber cable 5, and the transmission signal is demodulated by the transmission terminal station 2 to be a maintenance signal only. Is output from the maintenance signal output interface circuit of the maintenance unit 20B, and the maintenance signal is monitored using an external device (not shown).

The maintenance signal of the own transmission terminal station 2 input to the maintenance signal input interface circuit 21 of the maintenance unit 20B is also output from the maintenance signal output interface circuit 22 of the maintenance unit 20A via the same route. The maintenance unit 20 itself generates a maintenance signal, and
In the device which is detected and monitored by the maintenance unit 20 itself, the input / output interface circuits 21 and 22 are replaced by a maintenance signal generation circuit and a maintenance signal detection and monitoring circuit.

[0007]

The conventional monitoring method of the transmission terminal station is performed as described above, and since the maintenance signal is also transmitted / received via the same transmission line as the main signal, an optical fiber cable or the like is used. When a failure occurs in the transmission line or the intermediate relay station, there is a problem that not only the main signal but also the maintenance signal cannot be transmitted. In order to solve such a problem, a method is known in which a line switching circuit is provided in a backup transmission line and a transmission terminal station, and the line is switched to the backup transmission line when a failure occurs in the transmission line. The method is expensive and very economical.

The present invention has been made in order to solve such a problem. In a configuration in which two or more sets of transmission lines are arranged between two stations, one transmission line between transmission terminal stations or a relay station is provided. It is an object of the present invention to obtain a transmission terminal station monitoring system that can transmit and receive a maintenance signal between the transmission terminal stations where a failure occurs even if a failure occurs.

[0009]

A transmission terminal station monitoring system according to the present invention has two or more combinations of transmission terminal stations in which a pair of transmission terminal stations are connected via a transmission path between the two stations. In the data transmission system, when the transmission terminal stations of each station are connected by a maintenance signal line and a failure occurs in the transmission line of the combination between any of the transmission terminal stations, the combination between the failed transmission terminal stations It was decided that the maintenance signal transmission and reception in the above shall be performed using a combination between other transmission terminal stations in which no failure occurred.

As a prior art relating to the monitoring of a data transmission system, a technique for checking a spare transmission / reception circuit in advance in Japanese Patent Laid-Open No. 63-18737, "line monitoring switching system", Japanese Patent Laid-Open No. 1-227536. In the "optical transmission system monitoring method", there is disclosed a technique of accurately transmitting only failure information with an address when a failure occurs in a transmission terminal station or a repeater, which is the object of the present invention. It is not related to transmission line failure.

[0011]

In the present invention, the configuration having a plurality of transmission lines between the two stations is utilized, and the transmission terminal stations of each station are connected by the maintenance signal line so that the maintenance signals can be transmitted and received. Even if a failure occurs in a combination of transmission lines between any of the transmission terminal stations, maintenance signals can be transmitted and received between the transmission terminal stations in which the failure has occurred, even if there is no backup transmission line.

[0012]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the data transmission system shown in FIG. 1, two left and right stations (A station and B station) are connected via an optical fiber cable 5.
Station), two or more pairs of transmission terminal stations are arranged in parallel (in the embodiment, there are two transmission terminal stations 1 and 3 for station A and transmission terminals 2 and 4 for station B) for convenience of explanation. The configuration is shown, and this system is configured to mutually perform data transmission between the transmission terminal station 1 and the transmission terminal station 2 and between the transmission terminal station 3 and the transmission terminal station 4. In FIG. 1, 1 to 4 are transmission terminal stations, 5 is an optical fiber cable, and 6e to 6
Each h indicates a maintenance signal line.

FIG. 2 is a block diagram showing a pair of configurations of the transmission terminal station 1 and the transmission terminal station 2. In the figure, 10 is a transmission / reception unit for transmitting / receiving a main signal. In the transmission / reception unit 10, 11 is an input interface circuit for a main signal, 12 is a code conversion circuit for modulating an input signal into a transmission code, 13 is an electrical / optical conversion circuit for converting an electrical signal into an optical signal, and 14 is an optical signal. An optical / electrical conversion circuit for converting into an electric signal, 15 is a code demodulation circuit for demodulating a received code into a data signal, and 16 is an output interface circuit for a main signal. Further, 20 is a maintenance unit for transmitting and receiving maintenance signals. In the maintenance unit 20, 21 is a maintenance signal input interface circuit, 22 is a maintenance signal output interface circuit, and 23 is a transmission side (input side) maintenance signal switching circuit. , 24 are maintenance signal switching circuits on the receiving side (output side).

Next, the operation of the embodiment will be described. The main data signal a input to the transmission terminal station 1 is input to the input interface circuit 11 of the transmission / reception unit 10A, modulated into a transmission code by the code conversion circuit 12, and converted into an optical signal by the electrical / optical conversion circuit 13. It is transmitted to the transmission terminal station 2 via the optical fiber cable 5. In the transmission terminal station 2, the transmitted optical signal is converted into an electric signal by the optical / electrical conversion circuit 14,
The code demodulation circuit 15 demodulates the transmission code into a data signal, and the output interface circuit 16 outputs the main data signal a. The main data signal b transmitted from the transmission terminal station 2 is also transmitted to the transmission terminal station 1 via the same path and is output.

Next, a maintenance signal transmission system will be described. When the transmission line and the intermediate relay station (not shown) are normal, the maintenance signal switching circuit 23 on the input side connects the maintenance signal input interface circuit 21 and the code conversion circuit 12, and the maintenance signal switching circuit on the output side. Reference numeral 24 connects the code demodulation circuit 15 and the maintenance signal output interface circuit 22. Then, the maintenance signal of the own transmission terminal station 1 is input to the maintenance signal input interface circuit 21 from an external device (not shown), and the input maintenance signal is input to the code conversion circuit 12 via the maintenance signal switching circuit 23. Here, the transmission code superimposed on the main signal is converted into an optical signal by the electrical / optical conversion circuit 13 and sent to the transmission terminal station 2 via the optical fiber cable 5, and the optical / electrical conversion circuit 14 of the transmission terminal station 2 performs electrical conversion. After being converted into a signal and demodulated by the next code demodulation circuit 15, only the maintenance signal is separated, output from the maintenance signal output interface circuit 22 via the maintenance signal switching circuit 24, and communicated by an external device (not shown). The state is checked and the transmission terminal station 1 is monitored.

The transmission unit 2 is also monitored by the maintenance unit 2.
The maintenance signal of the own transmission terminal station 2 is input to the maintenance signal input interface circuit 21 of 0B, the maintenance signal is output from the maintenance signal output interface circuit 22 of the maintenance unit 20A through the same path, and the communication status is checked by the external device. Is
The transmission terminal station 2 is monitored. The main data signals c and d are transmitted between the transmission terminal stations 3 and 4 shown in FIG. 1 as described above, and the maintenance signal is transmitted in the same manner. The transmission terminal station is monitored.

Next, a case will be described in which a failure occurs in an optical fiber cable or an intermediate relay station (not shown) which is a transmission line connecting the transmission terminal stations 3 and 4 shown in FIG. Each of the transmission terminal stations 1 to 4 constantly monitors whether or not the optical signal is normally received, for example, by a frame sync signal deviation, a code error, or an optical signal input interruption. Is detected and an ALM (alarm) signal is output. When this ALM signal is output, each transmission terminal switches the maintenance signal switching circuits 23 and 24 of its own transmission terminal and the transmission terminal connected by the maintenance signal line 6. This operation is performed, for example, by transmitting an ALM signal through the maintenance signal line 6 so that the transmission terminal station connected to the maintenance signal line 6 receives the ALM signal and automatically transmits the ALM signal. The maintenance signal switching circuits 23 and 24 may be switched.

That is, when a failure occurs in the optical fiber cable 5 or the intermediate relay station, which is the transmission path connecting the transmission terminal station 3 and the transmission terminal station 4, the transmission terminal station 4 on the B station side handles this. Upon detection, the ALM signal is transmitted, the maintenance signal switching circuits 23 and 24 of the own transmission terminal station 4 and the transmission terminal station 2 are switched, and the transmission terminal station 3 on the A station side also detects this and ALM signal is detected.
A signal is transmitted and the maintenance signal switching circuits 23 and 24 of the own transmission terminal station 3 and the transmission terminal station 1 are switched. Therefore, the maintenance signal of the transmission terminal station 3 is transmitted through the maintenance signal line e from the transmission terminal station 1 to the optical fiber cable 5 which is normally connected.
Is transmitted to the transmission terminal station 2 via the maintenance signal line f and is input from the transmission terminal station 2 to the transmission terminal station 4 to connect the transmission terminal station 3 and the transmission terminal station 4. Even if a failure occurs in the transmission terminal station 3, the transmission terminal station 3 can be monitored by the transmission terminal station 4. Further, the transmission terminal station 4 can be monitored by using the maintenance signal line g and the maintenance signal line h.

Example 2. FIG. 3 is a block diagram for explaining the second embodiment of the present invention, in which the same reference numerals as those in FIG. 2 indicate the same or corresponding portions, and 25 is a maintenance signal multiplexing circuit.
26 is a maintenance signal separation circuit. In the above-mentioned Example 1,
Although the maintenance signal switching circuits 23 and 24 are provided in the maintenance unit 20 and the switching circuit is operated by the ALM signal, instead of the switching circuit, as in the second embodiment shown in FIG. By providing 25 and the maintenance signal separation circuit 26, the ALM signal can be output and
Even if one set of transmission lines fails without having to operate the switching circuit with the LM signal, the transmission and reception of the maintenance signal of the transmission line station that has failed is performed with the transmission lines of the other set and the transmission lines. You can use and to send and receive.

In the first and second embodiments described above, the data transmission system using the optical fiber cable is described as an example. However, data having two or more sets of transmission terminal stations between two stations and a plurality of transmission lines are provided. Any transmission system can be used regardless of the type of transmission line, and the transmission line such as a coaxial cable or a wireless line is not limited to an optical fiber cable. Further, the maintenance signal may be generated and detected in the maintenance unit 20, and various methods such as a voice signal may be used as the maintenance signal.

[0021]

As described above, the transmission terminal station monitoring system according to the present invention is designed so that, even if a failure occurs in one transmission line between the transmission terminal stations or its relay station, the failure occurs between the transmission terminal stations. You can send and receive maintenance signals with.

Further, it is not necessary to provide a spare transmission line, and there is an effect that an economical system can be constructed.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission terminal station according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a transmission terminal station according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of a conventional data transmission system.

FIG. 5 is a block diagram showing a configuration of a transmission terminal station in a conventional data transmission system.

[Explanation of symbols]

 1 to 4 transmission terminal station 5 optical fiber cable 6e to 6h maintenance signal line 10 transmission / reception unit 11 input interface circuit 12 code conversion circuit 13 electrical / optical conversion circuit 14 optical / electrical conversion circuit 15 code demodulation circuit 16 output interface circuit 20 maintenance Unit 21 Maintenance signal input interface circuit 22 Maintenance signal output interface circuit 23, 24 Maintenance signal switching circuit 25 Maintenance signal multiplexing circuit 26 Maintenance signal separation circuit

Claims (3)

[Claims] 1. A combination of two or more transmission terminal stations (hereinafter, tentatively referred to as a combination between transmission terminal stations) in which a pair of transmission terminal stations are connected to each other via a transmission path between the two stations. , In a transmission terminal station monitoring method in a data transmission system that transmits and receives data signals and maintenance signals in a combination between the respective transmission terminal stations, means for connecting the transmission terminal stations of each station with a maintenance signal line, When a failure occurs in the transmission line of the combination between the transmission terminal stations, the transmission and reception of the maintenance signal of the combination between the transmission terminal stations in which the failure has occurred are transmitted via the above maintenance signal line and other faults have not occurred. A method for monitoring a transmission terminal station, characterized by comprising means for performing a combination between the transmission terminal stations. 2. A means for transmitting and receiving a maintenance signal between transmission terminal stations of each station via the maintenance signal line detects the occurrence of a failure built in each transmission terminal station and automatically detects the transmission / reception circuit. 2. The monitoring method for a transmission terminal station according to claim 1, wherein the maintenance signal switching circuit is switched to. 3. A means for transmitting and receiving a maintenance signal between the transmission terminal stations of each station via the maintenance signal line is performed by a maintenance signal multiplexing circuit and a maintenance signal separation circuit built in each transmission terminal station. The method for monitoring a transmission terminal station according to claim 1, wherein: