JPH1198075A - Transmission line supervisory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line supervisory device which copes with multiple failures in a transmission line that is made redundant configuration. SOLUTION: Selectors 26 and 28 are provided in a repeater 42 that is arranged on a transmission line which is made redundant configuration, and when a transmission line failure occurs in a current optical fiber cable 12a, one selector 26 is switched and a coaxial cable 18 that is a spare transmission line is selected. With this, only a section where the failure occurs is partially switched to the spare transmission line and the transmission of a normal signal between terminal stations is maintained. When all optical fiber cables 12a and 16a simultaneously have transmission line failures in the same relaying section and a normal signal can not be acquired from an upstream, the other selector 28 selects a substitute signal from a backup oscillator 30 in the repeater and saves an downstream relay section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line monitoring device provided between terminal stations in an information transmission system for monitoring a redundantly configured transmission line, a repeater provided with the device, and transmission using the same. Road monitoring method.

[0002]

2. Description of the Related Art A transmission system that forms a network in an information communication network such as a public communication network includes a terminal at both ends of a transmission line, a transmission medium such as an optical fiber cable or a coaxial cable, and a signal deteriorated by the transmission medium. And a repeater provided in the middle of the transmission line for correction. Here, a section between two adjacent repeaters or between a terminal station and a repeater is referred to as a relay section. Since high reliability is required for such a transmission system, the reliability is increased by adopting a redundant configuration such as multiplexing transmission lines. When transmission lines are multiplexed, one of them is usually used as an active transmission line, and when the current transmission line becomes unusable due to wiring work of the transmission line or maintenance of equipment. , A signal is transmitted by switching to any other spare transmission path.

In the transmission line monitoring system according to the prior art,
Transmission path switching has been realized by a selector provided in the terminal station relay device. Here, the terminal repeater is an optical transmission line that is provided in the terminal station, converts a digital signal used in the station, converts the digital signal, and, if the transmission line is an optical transmission line formed of an optical fiber cable, corresponds to the optical transmission line. A device that transmits a pulse train to an optical transmission line and detects a transmission line failure by checking the coding rules and the like of a digital signal received through the transmission line. In this conventional transmission line monitoring system, when a transmission line failure occurs at a certain point in the working transmission line, one of the terminal relay devices provided in the terminal stations at both ends of the transmission line detects the failure, and both of them are detected. The transmission line is switched from the currently used transmission line to any of the spare transmission lines by a selector provided in the terminal station relay device. As a result, the spare transmission path that has been switched becomes a new working transmission path,
The currently used transmission path is disconnected from the transmission system until restoration.

[0004]

The conventional multiplex transmission line monitoring system as described above has the following limitations. When the current transmission line causes a transmission line failure in any of the relay sections, it is necessary to switch the transmission line by a selector provided in the terminal relay device, and to switch the entire transmission line to one of the backup transmission lines. Therefore, if all the spare transmission paths have already failed in any of the relay sections and have not been restored, the transmission path directly connecting the ground becomes unusable. Therefore, it is necessary to take measures such as switching to another detour in the terminal station device.

The present invention solves the above-mentioned drawbacks of the prior art by directly connecting the multiplexed transmission line to the ground even if all transmission lines have a transmission line failure in any of the relay sections. An object of the present invention is to provide a flexible and highly reliable transmission line monitoring device and a transmission line monitoring method capable of transferring a normal signal to a downstream relay section using a transmission path or relieving a downstream relay section. .

[0006]

According to the present invention, a selector is provided in one or more repeaters between transmission terminal stations. When a transmission path failure occurs in the current transmission path in a certain relay section, a signal including the transmission path failure transferred through the transmission path is blocked by controlling a selector provided in the repeater,
Instead, it selects a signal transferred through one of the other spare transmission lines in which no transmission line failure has occurred in the same relay section, and outputs it to the next relay section. That is, the transmission path is partially switched for each relay section. As a result, even if all multiplexed transmission paths cause transmission path failures in any of the relay sections, normal signal transmission is possible as long as those failures do not occur simultaneously in the same relay section.

According to the present invention, one or more repeaters between transmission end stations are provided with a further selector and a backup oscillator. If all transmission paths fail simultaneously in the same relay section, control the another selector to block all signals transferred through the relay section, and substitute for the backup oscillator instead. The signal is selected and output to the next relay transmission line. Thus, even if a normal signal from the upstream cannot be obtained, the transmission path of the downstream relay section is separated from the transmission system by detecting the substitute signal, so that the downstream relay section can be rescued.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a transmission line monitoring apparatus according to the present invention.

FIG. 2 shows a relay system of a transmission line monitoring system using the transmission line monitoring device according to the present invention. This system comprises terminal devices 40 at both ends, cables 12a, 12b, 16a, 16b, and one or more repeaters 42 for relaying multiplex transmission lines multiplexed by these. These repeaters 42 have the same configuration in the present system. This system differs from the conventional transmission line monitoring system shown in FIG. 3 in that not only the terminal device 40 but also each repeater 42 is provided with a selector 26 so that the transmission line can be switched for each relay section. Features.

FIG. 1 shows an embodiment of a transmission line monitoring apparatus according to the present invention. In this embodiment, two circuit boards for accommodating input / output optical fiber cables from the first path are provided in the repeater 42.
10A1 and 10B1 and two circuit boards 10A2 and 10B2 for accommodating input / output optical fiber cables from the second path. All four circuit boards have the same configuration. Typical operating systems for a redundantly configured system include a standby system (a system in which a certain device is on standby as a standby for an active device) and a synchronous operating system (a standby device is also synchronized in parallel with the active device in parallel). This is a method for operating the system, and the processing results of the active device and the standby device are constantly collated, so that the failure can be quickly detected and dealt with. However, this embodiment belongs to the latter. . Therefore, the optical fiber cables 12a and 12a
The transmission path composed of b and the coaxial cable 14 and the transmission path composed of the optical fiber cables 16a and 16b and the coaxial cable 18 are redundant transmission double transmission paths. , The same signal is transmitted synchronously and in parallel.

Here, a configuration common to each circuit board will be described. The optical-to-electrical converter 20 is connected to the repeater through optical fiber cables 12a and 16a, which are redundantly set in the repeater section, by a light receiving element such as an avalanche photodiode (APD) or a pin photodiode (pin-PD). This is a device that converts an input optical signal into an electric signal and sends it to the frame terminating device 22. The frame terminating device 22 identifies a received signal for each frame and checks a coding rule or the like, detects a transmission path failure in the immediately preceding relay section, and outputs a signal identified for each frame to the transfer processing device 24. Device. The detection of the transmission path failure is performed by detecting an error in the coding rule of the encoded signal. When a transmission path failure is detected in the immediately preceding relay section, the frame terminating device 22 outputs an alarm signal to the monitoring and driving device 36. The transfer processing device 24 is a device that receives a signal of one frame output from the frame terminating device 22, holds the signal in a buffer, and outputs the signal to the coaxial cable 14 or 18 after a certain delay time. In addition, the transfer processing device 24 is output from a selector 28 in the same board,
Receives a signal that is determined to be output to the next relay section and is transferred to a path opposite to the signal for the one frame described above, and applies equalized amplification, retiming, and identification reproduction to the deteriorated signal. Frame reproduction device
It is also a device to transfer to 32.

One selector 26 has two coaxial cables.
14 and 18, and selects a signal to be input through one of the cables and selects the other selector 28.
This is a device that outputs to Of the optical fiber cables 12a and 16a as input lines to the repeater 42, in the initial state, the signal transferred through the cable 12a is the working signal. Therefore, the selector 26 selects and outputs the signal transferred through the cable 14 for transferring the signal from the cable 12a.

The backup oscillator 30 is, for example, a pulse generator that constantly outputs a substitute signal called a blue signal. Specifically, the backup oscillator 30 uses a self-excited oscillator, a crystal oscillator, a tuning fork oscillator, or the like by a method of generating vibration. Can be considered. Also, a blue signal is a signal that does not have a coding rule error and conforms to the coding rule of the signal encoding performed by the terminal repeater. When the signal arrives at the terminal, it is a substitute signal instead of a normal signal. It contains predetermined information so that it can be recognized that there is.

The other selector 28 is a device that receives both the output signal from the one selector 26 and the output signal from the backup oscillator 30, selects one of them, and outputs it to the transfer processing device 24. As an initial state, the selector 28 selects a signal from the selector 26 from among the received signals and outputs the signal to the transfer processing device 24. The frame generation device 32 is a device that receives the signal output from the transfer processing device 24, generates a frame again by multiplexing the signal, and outputs the frame to the electro-optical converter 34. The electrical / optical converter 34 is a frame generator 32
Is a device that converts the multiplexed electric signal into an optical signal again by a light emitting element such as a semiconductor laser (LD) or a light emitting diode and outputs the optical signal to the optical fiber cable 12b or 16b.

The supervisory driving device 36 receives the alarm signal from the frame terminating device 22, transfers the alarm signal to the supervisory control device 38, and receives a control command from the supervisory control device 38, and selects the selectors 26 and 28. This is a device for switching between. The monitoring and control device 38, as conceptually indicated by the arrow 44,
A1 to 10B2 are connected to the monitoring and driving devices 36, collect alarm signals from the respective monitoring and driving devices 36, and send a control command for selector switching to each of the monitoring and driving devices 36 according to a predetermined matrix. It is.

According to the above configuration, if no transmission path failure occurs, the present embodiment operates as follows. That is, of the optical fiber cables 12a and 16a accommodated as input lines in the repeater 42, the signals input to the repeater through the working cable 12a are the optical fiber cables 12b and Output from 16b. The signal input to the repeater 42 through the spare optical fiber cable 16a is cut off by each selector 26 and is not output from the repeater 42.

When a transmission line failure occurs in the working optical fiber cable 12a accommodated in the repeater 42 as an input line, the present embodiment operates as follows. Frame termination device 22 in circuit board 10A1 or 10A2 that houses cable 12a
Detects this transmission path failure and sends an alarm signal to the monitoring and driving device 36 in the board 10A1 or 10A2. Circuit board 10
The monitoring driving device 36 in A1 or 10A2 monitors the alarm signal received from the frame terminating device 22 in the same board as the monitoring control device.
38, the transfer processing device 24 in the same board 10A1 or 10A2 transfers the signal of the present invention within a delay time until the transfer of one frame of signal including a transmission line failure held in a buffer in the same device 24 is performed. Performs the following processing.

The supervisory control device 38 firstly sends the supervisory drive devices 36 in the two circuit boards 10A2 and 10B2, or 10A1 and 10B1 provided on the side that outputs the signal for one frame from the repeater. , And sends a control command instructing switching to the spare transmission path. Each monitoring drive device 36 that has received this control command instructs one selector 26 in the same substrate on which each is provided to perform switching. Then, each selector 26 switches the selection of reception from the currently used coaxial cable 14 to the spare coaxial cable 18. As a result, the two circuit boards 10A2 and 10A that output signals
B2 or 10A1 and 10B1 are fiber optic cables 16a
Through the optical fiber cables 12b and 16b to the downstream repeater.
The monitoring device according to the invention thus transfers a normal signal downstream without disrupting synchronization.

A working optical fiber cable of a certain relay section
Since a transmission line failure occurred in 12a, the cable was switched to the spare cable 16a, and after the cable 16a became the working cable, before the restoration of the cable 12a, the transmission line failure also occurred in the working cable 16a in the same relay section. In other words, if a transmission line failure occurs in all the redundantly configured transmission lines that transfer signals in the same direction in the relay section (hereinafter, such a relay section is referred to as an all-failure section), It works as follows.

The frame terminating device 22 in the circuit board 10B1 or 10B2 accommodating the optical fiber cables 16a in all fault sections.
Detects the transmission path failure of the optical fiber cable 16a in the same manner as the frame termination device 22 in the circuit board 10A1 or 10A2 accommodating the optical fiber cable 12a of the entire failure section has detected the transmission path failure of the cable 12a. Sends an alarm signal to the monitoring control device 38. The supervisory control device 38 is a circuit board that outputs signals input to the repeater 42 from all faulty sections from the two repeaters 10A2 and 10B2, or 10A1 and 10B1.
A control command is transmitted to the monitoring drive device 36 to switch the other selector 28. Each monitoring drive device 36 that has received the control instruction is connected to the other selector 28 on the same substrate.
To select the reception of the substitute signal from the backup oscillator 30. As a result of selecting the substitute signal by the other selector 28, the circuit boards 10A2 and 10B2, or 10A1 and 10B
B1 sends the substitute signal sent by the backup oscillator 30 to the next relay section. Since this substitute signal has no coding rule error, it can reach the terminal via the downstream repeater,
By detecting the substitute signal, the terminal station can know that any of the relay sections has become the entire failure section. A terminal station that has learned of the occurrence of all faulty sections will eventually disconnect all relay sections located downstream from the transmission system. You.

In the embodiment of FIG. 1, the present invention has been described as a transmission line monitoring system in a duplex configuration (a configuration in which one spare transmission line is assigned to one working transmission line). The present invention can be similarly applied to a configuration in which the redundancy of transmission line multiplexing is increased and two or more spare transmission lines are assigned to one working transmission line.

The present invention is applicable not only to these synchronous operation systems but also to a standby system. For example, the number of active transmission lines is a plurality of n lines, and one of the standby transmission lines is put on standby as a backup when any of the active transmission lines fails, and the (n + 1) pairs of circuit boards are connected to a repeater. The present invention can also be applied to an (n + 1) common spare configuration (a configuration in which one spare transmission line is assigned to n active transmission lines) if the working and spare transmission lines are accommodated in preparation for the above. is there.

Although the embodiment of FIG. 1 is a transmission line monitoring system using an optical transmission line, the present invention can be applied to a transmission line using a balanced cable, a coaxial cable, or the like as a communication cable. It is.

[0024]

As described above, according to the present invention, when a transmission line failure occurs in an active transmission line in a relay section of a transmission system in which a plurality of transmission lines are redundantly set between the same grounds, The selector provided in each repeater ignores the signal transferred through the working transmission line in the relay section where the transmission path failure has occurred, and selects the signal transferred through the normal backup transmission path in the same relay section. And output from the repeater. That is, the transmission can be performed by partially using the spare transmission line in the relay section where the failure has occurred, instead of switching the entire working transmission line to the whole spare transmission line. Therefore, if there is at least one normal spare transmission path in a certain relay section, a faulty working transmission path is partially disconnected from the transmission system in that section and switched to the normal transmission path. A transmission path monitoring system can be provided, and no measures such as switching to a detour path in the terminal device are required.

Further, according to the present invention, since the repeater is provided with the backup oscillator, even if a normal signal from the upstream cannot be obtained due to the occurrence of all fault sections, another selector provided in the repeater can be used. Since the substitute signal transmitted from the backup oscillator is selected and output from the repeater, a highly stable redundant configuration and a transmission line monitoring method capable of relieving the downstream transmission line can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a transmission line monitoring device according to the present invention.

FIG. 2 is a diagram illustrating a relay system of a transmission line monitoring system having the device of FIG. 1;

FIG. 3 is a diagram illustrating a relay system illustrating an example of a transmission line monitoring system according to the related art.

[Explanation of symbols]

 10A1, 10A2, 10B1, 10B2 Circuit board 22 Frame termination device 26, 28 Selector 30 Backup oscillator 38 Monitoring and control device 40 Terminal device 42 Repeater

Claims (6)

[Claims] 1. A plurality of monitoring circuits respectively connected to a plurality of transmission paths from a first path, a selector circuit connected to a transmission path to a second path, and controlling the selector circuit. Monitoring control means, each of the monitoring circuits outputs an input signal arriving through a transmission path from the first path, and detects a failure in the transmission path by the input signal, Transmission path failure detection means for outputting an alarm signal when a failure is detected; transfer processing means for receiving and holding the input signal from the transmission path failure detection means and outputting it after a predetermined delay time; The selector circuit is connected to the transfer processing means, selects the input signal output from any of the connected transfer processing means, and outputs the input signal to a transmission path to the second path. The first selector hand Wherein the monitoring control means receives the alarm signal from the transmission path failure detecting means, controls the first selector means in accordance with the alarm signal, and receives the alarm signal from any of the transfer processing means. A transmission path monitoring apparatus, wherein said input signal to be output is selected by said first selector means. 2. The monitoring device according to claim 1, wherein the selector circuit further includes a backup oscillator connected to the first selector means and transmitting a substitute signal to the first selector means, Receiving the alarm signal from the transmission path failure detecting means, controlling the first selector means according to the alarm signal, and setting the input signal or the backup output from one of the transfer processing means; A transmission path monitoring device, wherein said substitute signal output from an oscillator is selected by said first selector means. 3. The monitoring device according to claim 1, wherein said selector circuit further comprises: a backup oscillator for transmitting a substitute signal; said backup oscillator connected to said first selector means; An oscillator and second selector means for receiving a signal from the first selector means, selecting one of the received signals, and outputting the selected signal to a transmission path to the second path. Wherein the monitoring control means receives the alarm signal from the transmission path failure detecting means, controls the second selector means in accordance with the alarm signal, and outputs the signal from any of the transfer processing means. A transmission line monitoring device for causing the second selector to select the input signal or the substitute signal output from the backup oscillator. 4. The apparatus according to claim 1, wherein the apparatus is arranged on a multiplex transmission path including the plurality of transmission paths and monitors a transmission path from the first path. And a repeater. 5. A step of detecting a failure of the multiplex transmission path at a relay point on the multiplex transmission path by a plurality of transmission paths, based on an input signal arriving through the multiplex transmission path from a first path. Selecting an input signal arriving from a multiplex transmission path from one path through a transmission path in which no failure is detected, and outputting the input signal to a multiplex transmission path to a second path. A transmission path monitoring method characterized by the above-mentioned. 6. The transmission line monitoring method according to claim 5, further comprising the step of, when a failure is detected in all of the multiplex transmission lines from the first path, transmitting the substitute signal to the second transmission line. A method of monitoring a transmission line, comprising a step of outputting to the multiplex transmission line to a line.