JPH07111493A - Digital relay transmission system - Google Patents

Abstract

PURPOSE:To obtain a digital relay transmission system by which the operating state is discriminated without confirming an installed station of a multiplexer terminal equipment by providing a means discriminating the operating state of a high speed optical signal transmission line to an optical repeater. CONSTITUTION:An optical recovery repeater 21 inserted into a high speed optical signal transmission line in compliance with the CCITT G.707, G.708, G.709 monitors a K2 byte in a multiple section overhead (MS-OH) included in a periodic transfer mode(STM) frame and an alarm generated by the repeater 21. Then the operating state of a high speed optical signal transmission line is discriminated based on a predetermined criterion according to the monitor result. Thus, when a maintenance personnel implements package replacement of the optical recovery repeater 21 and sets line control items again, the personnel discriminates the operating state of the transmission line for the installed station of multiplexer terminal station equipments 101, 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in an optical repeater of a digital repeater transmission system. In particular CCITT G.707, G.708, G.
The present invention relates to a monitoring device for an optical repeater inserted in a transmission line of a redundant digital repeater transmission system conforming to 709.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram of a digital relay transmission system. FIG. 12 is a diagram showing the structure of an STM frame of the digital relay transmission system. FIG. 13 is a switching sequence diagram showing the switching operation of the digital relay transmission system. FIG. 14 is a diagram showing the definition of the K1 byte of the multiple section overhead of the digital relay transmission system. FIG. 15 is a diagram showing the definition of the K2 byte of the multiple section overhead of the digital relay transmission system. FIG. 16 is a block diagram showing a redundancy configuration of a conventional digital relay transmission system.

In FIG. 11, a plurality of low speed optical signals are converted into high speed optical signals by a multiplexing terminal device (LT-MUX) 10 and transmitted. The transmitted high-speed optical signal is demultiplexed into a plurality of low-speed optical signals again by the multiplexing terminal device 10.
The high-speed optical signal output from the multiplexing terminal device 10 causes various interferences (attenuation, waveform distortion, noise, etc.) from the optical fiber.
Receive. An optical repeater (REP) 20 is used to remove these and lengthen the distance between the multiplexing terminal devices 10.

The optical repeater 20 includes an optical regenerator (3R-RE
P) and an optical linear repeater (1R-REP). The optical regenerator has functions of optical-electrical conversion, electric-optical conversion, equivalent amplification, retiming extraction, and identification reproduction. The optical signal that has been attenuated and distorted by being transmitted through the optical fiber is regenerated by the function of the optical regenerator and output.
The optical linear repeater has a function of amplifying an optical signal as it is, and compensates only the attenuation of the optical signal caused by being transmitted in the optical fiber (eg, Hagimoto, Aoyama: Relay using an optical fiber amplifier. Transmission system, IEICE Transactions B-1, Vol.75-B-1, No.5, p246, 1992). Optical regenerators have been introduced into commercial systems, but optical linear repeaters are still in research and development.

In accordance with the new synchronous interface recommended by the International Telegraph and Telephone Consultative Committee (CCITT), the Nippon Telegraph and Telephone Corporation (NTT) has introduced a synchronous digital hierarchy transmission system (SDH transmission system) from 1989.

Conventionally, the digital relay transmission system is shown in FIG.
11, the configuration shown in FIG.
0 ₁ , 10 ₂ and the optical regenerator 24.
In the digital repeater transmission method, both the low-speed optical signal and the high-speed optical signal are synchronized transfer mode frames (hereinafter,
It is called STM frame. ) Is used to enhance the monitoring function and improve system reliability. The STM frame is characterized by having an operation / maintenance information area (section overhead, S-OH) that is approximately 10% of the transmission rate. Section overhead can be classified into regenerator section overhead (RS-OH), pointer, and multiple section overhead (MS-OH). The regenerator section overhead is the optical regenerator 24.
It is also used for frame synchronization, error monitoring, etc. in the multiplexing terminal equipment 10 ₁ , 10 ₂ . The multiple section overhead is the multiplexing terminal equipment 10 ₁ , 10
It is used in _{2 for} system redundancy switching, error monitoring, etc. The optical regenerator 24 processes the upper three rows (regenerator section overhead) of the section overhead in the STM frame, and multiplex terminal equipment 10 ₁ ,
In 10 ₂ , all 9 lines of the section overhead in the STM frame (regenerator section overhead, pointer, multiple section overhead) will be processed.

In the configuration shown in FIG. 16, a service cut may occur due to a cable disconnection or a failure of the optical regenerator 24. In the digital relay transmission system of the synchronous digital hierarchy, in order to improve reliability, the multiplexing terminal equipment 1
There is a redundant transmission line between 0 ₁ and 10 ₂ . As a result, when a service interruption or service quality deterioration is detected,
It can be switched automatically. This is called system switching. The system of the backup transmission line 1 for the used transmission line 1 is called 1: 1 and the system of the backup transmission line 1 for the used transmission line N is called N: 1. FIG. 16 shows a 1: 1 configuration example.

CCITT G.783 defines switching of the synchronous digital hierarchy transmission system based on the K1 byte and K2 byte of the multiple section overhead. Bit assignments of the K1 byte and the K2 byte of the multiple section overhead defined by CCITT G.783 are shown in FIGS. 14 and 15. The K1 byte and the K2 byte each have 8 bits, and the first bit is represented by b1, and the second bit is represented by b2. CCITT G.78
3 considers a 1: 1 or N: 1 redundant system with switchback and a 1: 1 redundant system without switchback. here,
When the used transmission path has failed and switched to a backup transmission path and the used transmission path has been restored, switching is performed again. This is called switching with cutback.
In addition, even if the transmission line being used has a failure and the transmission line is switched to the backup transmission line, and the transmission line being used is restored, the switching is not performed again. This is called switching without switching back.

In the case of switchover without switchback, the transmission line that was spare after the switchover will continue to be used for providing services. When a transmission line that provides a service is called [working], in the case of switching without switching back, the [working] transmission line is changed after the switching. For this reason, the meaning of the K2 byte is slightly different between the switching with switching back and the switching without switching back. In the case of switching with switchback, the K2 byte represents the number of the transmission line connected to [spare]. In the case of switching without switching back, the K2 byte indicates the number of the [active] transmission line.

An example of switching a 1: 1 redundant system without switching back in the digital relay transmission system will be described with reference to FIG. The digital relay transmission system shown in FIG. 16 is a 1: 1 redundant system, and a transmission line with a transmission line number of "1" (hereinafter, a transmission line of "1") is provided between the multiplexing terminal station devices 10 ₁ and 10 _2. And a transmission line whose transmission line number is "2" (hereinafter referred to as "2" transmission line).

In the steady state, both multiplexing terminal equipments 10 ₁ ,
10 _2, mutually notifies the [no switching request]. The multiplexing terminal device 10 ₁ transmits the same signal to the downlink of the "1" transmission line and the "2" transmission line, and the multiplexing terminal device 10 ₂ first selects the "1" transmission line. is doing. Multiplexing terminal device 10
_{In 2} , when error detection or transmission line disconnection is detected from the downlink of the "1" transmission line, the "switching request" is notified to the multiplexing terminal station device 10 ₁ using the uplink. Multiplexing terminal device 10
₁ After confirming the "switching request", the switching to the transmission path of the selector of the device itself "2", and notifies the "switching response" to the multiplexing terminal station apparatus 10 _2. After receiving the "switching response" notified from the multiplexing terminal device 10 ₁ , the multiplexing terminal device 10 ₂
The selector of its own device is switched from the "1" transmission path to the "2" transmission path. When error detection or transmission path disconnection at multiplexer terminal station apparatus 10 ₂ is restored, multiplex terminal station apparatus 10 ₂ notifies the "recovery standby" to multiplexer terminal apparatus 10 _1. Both multiplexing terminal devices 10 ₁ and 10 ₂ confirm the normal state of the line for a certain period of time, and notify each other of “no switching request”.

[0012]

However, in such a digital relay transmission system of the conventional example, when the multiplexing terminal station device and the optical regenerator are used, the system switching is performed by the multiplexing terminal station. The device does this using multiple section overhead K1 and K2 bytes. Since the multiplexing terminal equipment switches the selector by itself, the multiplexing terminal equipment knows the usage status of the transmission path. For this reason, it is possible to notify the maintenance person or the monitoring system of the package related to the used transmission path. For example, an ACT lamp indicating that the package is related to the transmission path used is mounted on each package and turned on to notify a maintenance person of the usage state of the apparatus. When maintaining the multiplexing terminal equipment, the maintenance person can replace the package in which the ACT lamp is not lit even during the service.

On the other hand, in the optical regenerator, it was not known whether the transmission line was used or was not currently used because of the backup transmission line. Maintenance can be performed if the optical regenerator is not currently used because of the backup transmission line. However, if maintenance work is performed on an optical regenerator using a transmission line, service may be cut off. For this reason, at the station where the optical regenerator is installed, when the maintenance person replaces the package or resets the line control items, the multiplexing terminal equipment is used for the station where the multiplexing terminal equipment is installed. There was a problem that the condition had to be confirmed.

Further, the conventional digital repeater transmission system does not use an optical linear repeater. It is expected that a digital repeater transmission system using an optical linear repeater will be introduced in the future. Between multiplexed terminal equipment, or between optical regenerators,
Alternatively, a digital repeater transmission system using an optical linear repeater between the multiplexing terminal device and the optical regenerator repeater can be considered. Like the above-mentioned optical regenerator, the optical linear repeater does not know whether the transmission line is used or is not currently used because of the backup transmission line. Therefore, similar to the optical regenerative repeater, at the station where the optical linear repeater is installed, when the maintenance person replaces the package or resets the line control items, There is a problem that it is necessary to confirm the usage state of the optical linear repeater.

Since the optical linear repeater is an analog optical amplifier, it monitors the input optical power, output optical power, noise figure, current consumption of internal elements, etc. for self-diagnosis and failure evaluation. When a monitor value that exceeds a certain threshold is detected,
Judge as deterioration or failure. Even if the optical linear repeater self-determines that it has deteriorated or has failed, the optical regenerator or the multiplexing terminal equipment located downstream does not always detect the deterioration of the quality of the transmission path. That is, even if the optical linear repeater self-determines deterioration or failure, the system switching does not operate, and there is a possibility that the optical linear repeater judged to be deteriorated or failed is used. This is because the optical regenerator and the multiplexing terminal equipment detect the code error of the digital signal, but the optical linear repeater cannot recognize the digital signal. Even if the optical linear repeater self-diagnoses as a deterioration or failure and notifies the maintenance person by a lamp etc., it is possible to know whether the transmission line including the optical linear repeater is used or not because it is a standby transmission line. Absent. For this reason, even if the optical linear repeater self-determines that it has deteriorated or has failed, at the station where the optical linear repeater is installed, when the maintenance personnel replace the package or reset the line control items, the It is necessary to confirm the usage status of the optical linear repeater with the installation station of the terminal equipment.

The present invention solves the above-mentioned drawbacks. When a maintenance person replaces a package of an optical repeater or resets a line control item, a usage state of a transmission line is set in an installation station of a multiplexing terminal device. It is an object of the present invention to provide a digital relay transmission system that can be discriminated without checking.

[0017]

SUMMARY OF THE INVENTION The present invention is a CCITT
G. 707, G.I. 708, G.I. 709, a high-speed optical signal transmission line, and a digital repeater transmission system including an optical repeater inserted in the transmission line. In the digital repeater transmission system, the optical repeater is a multiple transfer frame included in a synchronous transfer mode frame (STM frame). Section overhead (MS-OH)
It is characterized in that it comprises means for monitoring the K2 byte in the above and an alarm generated by the own device, and means for judging the use state of the transmission path on the basis of a predetermined reference based on the monitoring result.

The present invention can also include means for concurrently monitoring the K1 byte.

Further, according to the present invention, means for displaying the judgment result of the judgment means can be provided.

When an optical linear repeater is inserted in the transmission line, the determination result of the determination means obtained by the device on the upstream side of the optical linear repeater is transmitted to the optical linear repeater. A monitoring line different from the above-mentioned transmission line can be provided.

[0021]

In the case of a redundant system with switchback, the optical regenerator repeats monitoring of the K2 byte in the multiple section overhead included in the STM frame and the alarm generated by itself, or of the redundant system without switchback. In case ST
The K1 byte and the K2 byte in the multiple section overhead included in the M frame and the alarm generated by the self-device are monitored, and the result of this monitoring is used to determine the state of use of the transmission path on the basis of a predetermined criterion, and this determination result is displayed. In addition, in the case of an optical linear repeater, the usage status of the transmission path notified from the upstream device via the monitoring line and the alarm generated by the equipment itself are used to determine the usage status of the transmission path according to specified standards. Display the judgment result. As a result, when the maintenance person replaces the package of the optical repeater or resets the line control items, it can be determined without confirming the usage state of the transmission path with the installation station of the multiplexing terminal equipment.

[0022]

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

FIG. 1 is a block diagram of a digital relay transmission system according to the first embodiment of the present invention. In FIG. 1, the digital repeater transmission system includes a high-speed optical signal transmission line conforming to CCITT G.707, G.708, and G.709, and an optical regenerator 21 as an optical repeater inserted in this transmission line. , And multiplex terminal devices 10 _{1 and} 10 ₂ provided at both ends of this transmission path.

Here, the feature of the present invention is that the optical regenerator 21 monitors the K2 byte in the multiple section overhead included in the STM frame and the alarm generated by the own device, and the result of this monitoring. And a means for judging the use state of the transmission path according to a predetermined standard.

An ACT lamp is provided as a means for displaying the determination result of the determining means.

The operation of the optical repeater having such a configuration will be described.

FIG. 1 shows a digital relay transmission system having an N: 1 redundant system configuration. FIG. 2 is a diagram showing transition conditions for turning on and off the ACT lamp of the optical regenerative repeater of the digital repeater transmission system according to the first embodiment of the present invention. FIG. 3 is a transition diagram of lighting and extinguishing of the ACT lamp of the optical repeater of the digital repeater transmission system according to the first embodiment of the present invention. Here, FIG.
FIG. 3A shows a case where the transmission line number is “0”, and FIG.
(B) shows the case where the transmission path number is other than "0". In FIG. 1, when the optical regenerator 21 determines the use state of the transmission line, it can be notified to the maintenance person or the monitoring system by lighting the lamp, changing the voltage, changing the resistance, issuing a message, or the like. Here, as a specific means, a case will be described in which an ACT lamp is mounted on the optical regenerator 21 in a system having an N: 1 redundant system with switchback. In FIG. 2, three consecutive receptions of the same content are recognized as transition conditions, ... indicates that the transition conditions are arbitrary, and when a plurality of transition conditions are monitored at the same time, transition is performed with the following priority, a>b> c, d TF indicates output cutoff, LOS indicates input cutoff, and LOF indicates loss of frame synchronization. FIG. 2 shows transition conditions for turning on and off the ACT lamp in the optical regenerator 21 of the system having the N: 1 redundant system with switchback. The transition conditions for turning on and off the ACT lamp can be classified into five items a to e. Where K2
Bytes (b1-b4) indicate the transmission line number connected to the backup transmission line.

When the optical regenerator 21 is turned on and the system is started up, the optical regenerator 21 is set as to which of its own transmission path numbers is "0" to "15". I do. “0” is set for the backup transmission line, “1” to “14” is set for the used transmission line, and “15” is set for the EXTRA TRAFFIC.

First, to the "0" transmission line (spare transmission line),
A case where the optical regenerator 21 is connected will be described. Based on the transition condition (FIG. 2) determined by the up and down K2 bytes and the monitor content of the alarm, the ACT lamp is turned on and off as shown in FIG. 3 (a). This transition condition is determined by the upward and downward K2 bytes and the alarm of the own device. For example, when the optical input disconnection (LOS) is detected in the own device, the transition condition is a.

The optical regenerator 21 connected to the "0" transmission line (spare transmission line) is irrespective of the use state of the transmission line.
Turn off the ACT lamp when the system is started up. While the ACT lamp of the optical regenerator 21 is off, a, b, c, e
If it is detected, since the transmission path of "0" is not in use, the ACT lamp is kept turned off.

A is an input disconnection (TF) in the transmission line,
This is when a failure such as output loss (LOS) and loss of frame synchronization (LOF) has occurred. When a failure occurs in the "0" transmission line, the switching to the "0" transmission line is no longer performed, so that the "0" transmission line is unused. Because of this, A
The CT lamp remains off.

B is an MS-AIS (Alarm Indication Signal)
, Alarm display signal), FERF (Far EndReceive Failure,
Far end reception failure) is monitored. When MS-AIS and FERF are monitored on the "0" transmission line, the ACT lamp of the optical regenerator 21 connected to the "0" transmission line is unused because the "0" transmission line is unused. Keeps going out.

"C" is the case where "transmission path number 0" is monitored in K2 bytes (b1-b4). This means that the backup transmission line is connected to the transmission line number 0, that is, the backup transmission line is not used, and the transmission line of "0" is unused. For this reason, the ACT lamp continues to be turned off.

E is a condition when the switching sequence is not completed, such as when the contents of the bidirectional K2 bytes (b1-b4) are not equal. Since this state is indeterminate,
The ACT lamp remains off.

When d is detected while the ACT lamp of the optical regenerator 21 is turned off, the transmission path of "0" is in use, so the ACT lamp is turned on. d is the case where "other than transmission line number 0" is monitored in K2 byte (b1-b4). This means that the backup transmission line is connected to a transmission line number other than 0, that is, the backup transmission line is used, and the transmission line of "0" is in use. Therefore, the ACT lamp is turned on.

When d and e are detected while the ACT lamp of the optical regenerator 21 connected to the "0" transmission line is lit, the "0" transmission line is in use, so the ACT lamp Continue to light. d is the case where "other than transmission line number 0" is monitored in K2 byte (b1-b4). This means that the backup transmission line is connected to a transmission line number other than 0, that is, the backup transmission line is used, and the transmission line of "0" is in use. Because of this, AC
The T lamp continues to light.

E is a condition when the switching sequence is not completed, because the contents of bidirectional K2 bytes (b1-b4) are not equal. Since this state is indeterminate,
The ACT lamp continues to light.

When a, b, c are detected while the ACT lamp of the optical regenerator 21 connected to the "0" transmission line is lit, the "0" transmission line is unused. Turn off the ACT lamp. “A” indicates a case where a failure such as an input disconnection, an output disconnection, and loss of frame synchronization occurs in the “0” transmission path. If a failure occurs in the 0 ”transmission line,
Since switching to the transmission path of "0" will not be performed, "0"
The transmission line of is unused. Therefore, the ACT lamp is turned off.

B is a case where MS-AIS and FERF are monitored. When MS-AIS and FERF are monitored on the "0" transmission line, the "0" transmission line is unused,
ACT of the optical regenerator 21 connected to the "0" transmission line
The lamp goes off.

C is the case where the "transmission path number 0" is monitored in the K2 byte (b1-b4). This means that the backup system is connected to the transmission line number, that is, the backup transmission line is not used, and the transmission line of "0" is unused. Therefore, the ACT lamp is turned off.

Next, a case where the optical regenerator 21 is connected to a transmission line other than "0" will be described. Based on the transition condition (Fig. 2) determined by the up and down K2 bytes and the monitor content of the alarm, the ACT lamp is turned on and off.
The transition is made as shown in FIG. The optical regenerator 21 connected to the transmission path other than “0” is connected to the AC of the transmission path other than “0” when the system is started, regardless of the usage state of the transmission path.
Turn on the T lamp. Optical regenerator 2 connected to a certain transmission line other than "0" (in this example, "n")
When d and e are detected while the ACT lamp 1 is on,
Since the "n" transmission line is in use, the ACT lamp is kept on. d is "2" in K2 byte (b1-b4)
"Other" is monitored. This means that the backup transmission line is connected to a transmission line other than “n”, that is, the transmission line “n” is not connected to the backup transmission line, and the transmission line “n” is in use. Becomes For this,
The ACT lamp continues to light.

"E" is a condition when the switching sequence is not completed, because the contents of bidirectional K2 bytes (b1-b4) are not equal. Since this state is indeterminate,
The ACT lamp continues to light.

ACT of the optical regenerator 21 connected to a certain transmission line other than "0" (in this example, "n")
If "a", "b", and "c" are detected while the lamp is on, "n"
Since the transmission line of is unused, the ACT lamp is turned off. The case a is a case where a failure such as an input disconnection, an output disconnection, and a loss of frame synchronization occurs on the transmission line.
The "n" transmission line is unused and the ACT lamp is turned off.

In the case of b, MS-AIS and FERF are monitored. When MS-AIS and FERF are monitored on the "n" transmission line, the "n" transmission line is unused,
ACT of the optical regenerator 21 connected to the "n" transmission path
The lamp goes off.

C is the case where the "transmission path number n" is monitored in the K2 byte (b1-b4). This means that "n" transmission lines are connected to the backup transmission line, that is, "n".
Means that the transmission line of “n” has been switched to the backup transmission line, and the transmission line of “n” is unused. Because of this, A
The CT lamp goes off.

ACT of the optical regenerator 21 connected to a certain transmission line other than "0" (in this example, "n")
If a, b, c, e is detected while the lamp is off,
Since the "n" transmission path is unused, the ACT lamp continues to be turned off. The case a is a case where a failure such as input disconnection, output disconnection, loss of frame synchronization, or the like occurs in the transmission path. The "n" transmission path is unused and the ACT lamp continues to be turned off.

B is the case where MS-AIS and FERF are monitored. When MS-AIS and FERF are monitored on the "n" transmission line, the "n" transmission line is unused,
ACT of the optical regenerator 21 connected to the "n" transmission path
The lamp remains off.

C is the case where the "transmission path number n" is monitored in the K2 byte (b1-b4). This means that "n" transmission lines are connected to the backup transmission line, that is, "n".
Means that the transmission line of “n” has been switched to the backup transmission line, and the transmission line of “n” is unused. Because of this, A
The CT lamp remains off.

E is a condition when the switching sequence is not completed, because the contents of bidirectional K2 bytes (b1-b4) are not equal. Since this state is indeterminate,
The ACT lamp continues to light.

ACT of the optical regenerator 21 connected to one transmission line other than "0" (in this example, "n")
If d is detected while the lamp is off, the transmission path of "n" is in use, so the ACT lamp is kept on. d is the case where "other than" n "" is monitored in the K2 byte (b1-b4). This means that the backup transmission line is connected to a transmission line other than the "n" transmission line, that is, the "n" transmission line is not connected to the backup transmission line,
The "n" transmission path is in use. Therefore, the ACT lamp is turned on.

FIG. 4 is a block diagram of the digital relay transmission system of the second embodiment of the present invention. FIG. 5 is a diagram showing transition conditions for turning on and off the ACT lamp of the optical regenerative repeater of the digital repeater transmission system according to the second embodiment of the present invention. FIG. 6 is a transition diagram of lighting and extinguishing of the ACT lamp when the assigned transmission path number of the optical repeater of the digital repeater transmission system of the second embodiment of the present invention is "1". FIG. 7 is a transition diagram of lighting and extinguishing of the ACT lamp when the transmission line number assigned to the optical repeater of the digital repeater transmission system of the second embodiment of the present invention is "2".

The second embodiment is different from the first embodiment in that an ACT lamp is mounted on an optical regenerator in a system having a 1: 1 redundant system without switching back. In FIG. 5, forced switching means forced switching, transmission line failure, quality deterioration,
Indicates either recovery standby or switching response, recognizes that three consecutive receptions of the same content are transition conditions, ... indicates that it is optional, and if multiple transition conditions are monitored at the same time, A>b> c, d, e, f TF indicates output cutoff, LOS indicates input cutoff, and LOF indicates loss of frame synchronization.

FIG. 5 shows the turn-on and turn-off transition conditions of the ACT lamp in the optical regenerator 22 of the system having a 1: 1 redundant system without switchback. The lighting and extinguishing transition conditions of the ACT lamp can be classified into seven items a to g. Here, the K2 byte (b1-b4) indicates the transmission line number of the transmission line called "active". This does not change until the cause of the switching occurs, the switching is performed due to the cause, and the "switching operation" until the cause of the switching is recovered by some action is completed. That is, the term "active" as used herein is not a word indicating whether a transmission line is used or not, but a transmission line which provides a service when the failure is recovered and is normal.

When the optical regenerator 22 is turned on and the system is started up, the optical regenerator 22 is set to be used in the transmission path having the transmission line number "1" or "2". To do.

First, the optical regenerator 2 is connected to the "1" transmission line.
A case of connecting 2 will be described. Up and down K1, K2
Based on the transition condition (FIG. 5) determined by the monitoring contents of the byte and the alarm, the ACT lamp is turned on and off as shown in FIG. The optical regenerator 22 is "1" when the system is started, regardless of the usage status of the transmission path.
The ACT lamp of the transmission line of is turned on. When c, d, and g are detected while the ACT lamp is lit, it is determined that the transmission path of "1" is in use, and the ACT lamp continues to be lit. In the case of “c”, the transmission line of “1” is the working transmission line, both the upstream and downstream directions are normal, and there is no switching request.
At this time, the optical regenerator 2 connected to the "1" transmission line
2 continues to light the ACT lamp.

When the transmission path of "2" is currently used, d causes some failure and forced switching in both the upstream and downstream directions, and K1 of the content such as transmission line failure in the optical regenerator 22. This is the case when bytes are monitored. At this time, the transmission line in use is the "1" transmission line. Therefore, the optical regenerator 22 connected to the "1" transmission line turns on the ACT lamp.

G is a condition when the switching sequence is not established, for example, a switching request in only one direction, K1 and K2 bytes of contents such as undefined bit assignments are monitored. Since this state is an uncertain state, the ACT lamp continues to be turned on.

When the optical regenerator 22 connected to the "1" transmission line detects a, b, e, and f while the ACT lamp is lit, the "1" transmission line is unused. So ACT
The lamp goes off. a is an input break in the transmission line,
This is the case when a failure such as an output interruption or loss of frame synchronization occurs. When a failure occurs in the "1" transmission line, switching is performed, so that the "1" transmission line is unused.
Therefore, the ACT lamp is turned off.

In the case of b, MS-AIS and FERF are monitored. When MS-AIS and FERF are monitored on the "1" transmission line, the "1" transmission line is unused,
ACT of the optical regenerator 22 connected to the "1" transmission line
The lamp goes off.

E is a case where the upstream and downstream directions are normal when the "2" transmission line is in use and there is no switching request. At this time, the transmission path of "2" is in use and "1"
The ACT lamp of the optical regenerator 22 connected to the transmission line is turned off.

In the case where the transmission line of "1" is currently used, f causes some failure and forced switching in both the upstream and downstream directions, and the K1 byte of contents such as transmission line failure is the optical regenerative repeater. This is the case when it is monitored at 22.
At this time, the transmission line in use is the "2" transmission line. Therefore, the optical regenerator 2 connected to the "1" transmission line
2 turns off the ACT lamp.

When a, b, e, f, and g are detected while the ACT lamp of the optical regenerator 22 connected to the "1" transmission line is turned off, the "1" transmission line is not in use. Therefore,
The ACT lamp goes out. The condition of "a" is when a failure such as an input disconnection, an output disconnection and a loss of frame synchronization occurs in the transmission line. If a failure occurs in the "1" transmission line, the "1" transmission line is unused.
ACT of the optical regenerator 22 connected to the "1" transmission line
The lamp remains off.

The condition of b is that MS-AIS,
This is the case when FERF is monitored. When MS-AIS and FERF are monitored on the "1" transmission line, the ACT of the optical regenerator 22 connected to the "1" transmission line is because the "1" transmission line is unused. The lamp remains off.

E is a case where both the up and down directions are normal and there is no switching request when the "2" transmission line is in use. At this time, the transmission line of "2" is in use and "1"
The ACT lamp of the optical regenerator, which is connected to the transmission line of, continues to be turned off.

In the case of f, there is some kind of failure in the currently used transmission path "1", and the K1 byte of the contents such as forcible switching in both the up and down directions and the failure of the transmission path is monitored. At this time, the transmission line in use is the spare "2" transmission line. Therefore, the ACT lamp of the optical regenerator 22 connected to the "1" transmission line continues to be turned off.

G is a condition when the switching sequence is not established, such as when a switching request in only one direction or an undefined bit assignment is monitored. Since this state is an uncertain state, the current ACT lamp continues to be turned off.

Optical regenerator 2 connected to the "1" transmission line
When c and d are detected while the ACT lamp of 2 is off,
Since the "1" transmission line is in use, the ACT lamp is turned on. In the case of “1”, when the transmission path of “1” is in use, both the upstream and downstream directions are normal and there is no switching request. At this time, the transmission line of "1" is in use and "1"
The ACT lamp of the optical regenerator 22 connected to the transmission line is turned on.

D is a case where there is some failure in the currently used transmission path "2" and the contents such as forced switching in both the upstream and downstream directions and transmission path failure are monitored in K1 bytes. At this time, the transmission line in use is the backup "1" transmission line. Therefore, the ACT lamp of the optical regenerator 22 connected to the "1" transmission line is turned on.

Next, the case of connecting to the "2" transmission path will be described. Based on the transition conditions (FIG. 5) determined by the up and down K1 and K2 bytes and the monitor contents of the alarm, the ACT lamp is turned on and off as shown in FIG.
It changes like. The optical regenerator 22 uses the ACT at system startup regardless of the usage status of the "2" transmission line.
Turn off the lamp. The concept of the transition of turning on and off the ACT lamp is the same as in the previous example, and therefore will be omitted.

FIG. 8 is a block diagram of the digital relay transmission system of the third embodiment of the present invention. FIG. 9 is a diagram showing transition conditions for turning on and off the ACT lamp of the optical linear repeater of the digital repeater transmission system according to the third embodiment of the present invention. Figure 10
FIG. 8 is a transition diagram of lighting and extinguishing of an ACT lamp of an optical linear repeater of a digital repeater transmission system according to a third embodiment of the present invention.
In FIG. 9, three consecutive receptions of the same content are recognized as transition conditions, ... indicates that the transition conditions are arbitrary, and when a plurality of transition conditions are monitored at the same time, transition is performed with the following priority, a> b, c> d TF indicates output disconnection and LOS indicates input disconnection.

When the optical linear repeater 24 determines the use state of the transmission line, it can be notified to the maintenance person or the monitoring system by lighting the lamp, changing the voltage, changing the resistance, issuing a message, or the like.

Since the optical linear repeater 24 amplifies an optical signal as it is, it cannot read the information in the section overhead in which the usage state is written. Therefore,
It is necessary to get notification of the usage status. here,
Optical line repeater dedicated monitoring line different from the main signal (hereinafter, SV
Called a line. ) Is used to explain the usage status from the multiplexing terminal device and the optical regenerator 23.
FIG. 8 is an example of a digital repeater transmission system in which an optical linear repeater 24 is connected between the optical regenerator repeaters 23. In this example,
An SV line is installed between the optical regenerator 23 and the optical linear repeater 24. This SV line is installed in a pair (up, down) for each relay section. The optical linear repeater 24 is notified of the usage status determined by the upstream optical regenerator 23 (the optical regenerator described in the first and second embodiments) via the SV line. Specifically, the usage state is expressed by signal bits and bytes of the SV line, and the usage state is monitored by the optical linear repeater 24.

An optical linear repeater 2 in a system having a 1: 1 redundant system is used as means for notifying a maintenance person or a monitoring system.
A case in which the ACT lamp is mounted on 4 will be described. FIG. 9 shows transition conditions for turning on and off the ACT lamp in the optical linear repeater 24 of the system having the 1: 1 redundant system.
The transition conditions for turning on and off the ACT lamp can be classified into four items a to d. For example, if one of the upstream and downstream sides is the optical input disconnection (LOS), it becomes a. Based on the transition condition of FIG. 9, turning on and off of the ACT lamp makes a transition as shown in FIG. The optical linear repeater 24 turns off the ACT lamp when the system is started up, regardless of the use state of the transmission path.

A case where a certain transition condition is monitored while the ACT lamp is off will be described below. “A” is a case where an alarm such as output interruption or input interruption is generated while the ACT lamp of the optical linear repeater 24 is turned off. At this time, the transmission line is unused, and the AC of the optical linear repeater 24 connected to the transmission line is used.
The T lamp remains off.

The case b is a case where the usage state from the upstream is monitored as being in use while the ACT lamp of the optical linear repeater 24 is off. At this time, the transmission line is in use, and the ACT lamp of the optical linear repeater 24 connected to the transmission line is turned on.

FIG. 7C shows the case where the ACT lamp of the optical linear repeater 24 is turned off and the usage state from the upstream side is monitored as being unused. At this time, the transmission line is unused
The ACT lamp of the optical linear repeater 24 connected to the transmission line continues to be turned off.

D is a case where information other than the transition conditions a, b, and c is monitored while the ACT lamp of the optical linear repeater is off. At this time, since the use state of the transmission path is uncertain, the state of the ACT lamp is continued and turned off.

A case where a certain transition condition is monitored while the ACT lamp is on will be described below. The case a is a case where an alarm such as an input disconnection or an output disconnection is generated while the ACT lamp of the optical linear repeater 24 is turned on. At this time, the transmission line is unused and the optical linear repeater 2 connected to the transmission line
The ACT lamp of 4 is turned off.

The case b is a case where the ACT lamp of the optical linear repeater 24 is on and the usage state from the upstream is monitored as being in use. At this time, the transmission line is unused
The ACT lamp of the optical linear repeater 24 connected to the transmission line keeps lighting.

FIG. 10C shows a case where the ACT lamp of the optical linear repeater 24 is on and the usage state from the upstream is monitored as unused. At this time, the transmission line is not in use, and the ACT of the optical linear repeater 24 connected to the transmission line is
Turn off the lamp.

D is a case where information other than the transition conditions a, b, and c is monitored while the ACT lamp of the optical linear repeater 24 is on. At this time, since the use state of the transmission path is indefinite, the ACT lamp state is kept and the light is turned on.

As described above, the case where the optical linear repeater is provided between the optical regenerative repeaters has been described. However, the optical linear repeater is provided between the multiplexing terminal station devices or between the optical regenerative repeater and the multiplexing terminal station. Even when it is provided between the device and the device, the usage state can be similarly determined.

[0083]

As described above, according to the present invention, in the optical regenerator, the redundant system with the switchback has K2 bytes and the alarm, and the redundant system without the switchback has the K1 byte. The usage status of the transmission line can be determined by the K2 byte and the alarm. Further, in the optical linear repeater, the state of use of the transmission line can be determined by notifying from the upstream device via the SV line. Therefore, the ACT lamp can be mounted on the optical regenerative repeater and the optical linear repeater, the maintenance person can be accurately notified of the usage status of the main signal package, and the maintenance of the optical regenerative repeater and the optical linear repeater can be performed. It has an excellent effect that can be surely executed.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital relay transmission system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing transition conditions for turning on and off an ACT lamp of an optical regenerative repeater of a digital relay transmission system according to the first embodiment of the present invention.

FIG. 3 is a transition diagram of lighting and extinguishing of an ACT lamp of an optical regenerative repeater of a digital relay transmission system according to the first embodiment of the present invention.

FIG. 4 is a block configuration diagram of a digital relay transmission system according to a second embodiment of the present invention.

FIG. 5 is a diagram showing transition conditions for turning on and off an ACT lamp of an optical regenerative repeater of a digital repeater transmission system according to a second embodiment of the present invention.

FIG. 6 A in the case where the transmission line number assigned to the optical regenerative repeater of the digital repeater transmission system according to the second embodiment of the present invention is “1”
Transition diagram of turning on and off the CT lamp.

FIG. 7 A in the case where the transmission line number assigned to the optical repeater of the digital repeater transmission system according to the second embodiment of the present invention is “2”
Transition diagram of turning on and off the CT lamp.

FIG. 8 is a block configuration diagram of a digital relay transmission system according to a third embodiment of the present invention.

FIG. 9 is a diagram showing transition conditions for turning on and off an ACT lamp of an optical linear repeater of a digital repeater transmission system according to a third embodiment of the present invention.

FIG. 10 is a transition diagram of lighting and extinction of an optical linear repeater ACT lamp of a digital repeater transmission system according to a third embodiment of the present invention.

FIG. 11 is a block configuration diagram of a digital relay transmission system.

FIG. 12 is a block diagram of an STM frame of a digital relay transmission system.

FIG. 13 is a switching sequence diagram showing a switching operation of the digital relay transmission system.

FIG. 14 is a diagram showing the definition of K1 byte of multiple section overhead of the digital relay transmission system.

FIG. 15 is a diagram showing the definition of K2 bytes of multiple section overhead of the digital relay transmission system.

FIG. 16 is a block diagram of a conventional digital relay transmission system.

[Explanation of symbols]

10 ₁ 10 ₂ Multiplexing terminal equipment 20 Optical repeater 21, 22, 23, 24 Optical regenerative repeater 24 Optical linear repeater

Claims (4)

[Claims] 1. CCITT G.M. 707, G.I. 708,
G. 709, a high-speed optical signal transmission line and a digital repeater transmission system including an optical repeater inserted in the transmission line, wherein the optical repeater is a multiple transfer mode frame (STM frame). It is characterized by including means for monitoring the K2 byte in the section overhead (MS-OH) and an alarm generated by the device itself, and means for judging the use state of the transmission path on the basis of a predetermined reference based on the monitoring result. Digital relay transmission system. 2. The digital relay transmission system according to claim 1, further comprising means for simultaneously monitoring the K1 byte. 3. The digital relay transmission system according to claim 1, further comprising means for displaying a determination result of said determination means. 4. When an optical linear repeater is inserted in the transmission line, the determination result of the determination means obtained by a device upstream of the optical linear repeater is transmitted to the optical linear repeater. The digital relay transmission system according to claim 1 or 2, further comprising a monitoring line different from the transmission line.