JP3326760B2 - Monitoring method and monitoring system for optical transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital optical system comprising a multiplexing terminal device, a regenerative repeater, a linear repeater, etc., and an optical fiber connecting these components, and having a main signal line and a monitoring line. The present invention relates to a transmission path monitoring method and a monitoring system.

[0002]

2. Description of the Related Art A general digital relay transmission system is shown in FIG. The plurality of low-speed optical signals are converted into high-speed optical signals by a multiplexing terminal device (hereinafter, referred to as LT-MUX) and transmitted. The high-speed optical signal after transmission is LT-MUX
Is again separated into a plurality of low-speed optical signals. LT-M
The high-speed optical signal output from the UX receives various disturbances (attenuation, waveform distortion, noise, etc.) from the optical fiber. In order to remove these and increase the distance between the LT and the MUX, a regenerative repeater (hereinafter referred to as R-REP) is used. R-REP
Has functions such as light-to-electric conversion, electric-to-light conversion, equivalent amplification, retiming extraction, and identification reproduction. The optical signal that has been attenuated and distorted by being transmitted through the optical fiber
It is reproduced and output by the function of R-REP.

In accordance with the new synchronous interface recommended by the International Telegraph and Telephone Consultative Committee (CCITT), Nippon Telegraph and Telephone Corporation (NTT) has introduced an SDH transmission system since 1989. This SDH transmission system realizes the configuration shown in FIG. As shown in FIG.
The section between P or between the LT-MUX and the R-REP is called a regenerator section (= reproduction section), and the section between the LT and MUX is called a multiplex section (= multiplex section). In the SDH transmission system, both low-speed and high-speed signals
Using the Synchronons Transport Module (STM) frame shown, the monitoring function is enhanced and the reliability of the system is improved. The STM frame is characterized by having an operation and maintenance information area (section overhead, hereinafter referred to as S-OH) corresponding to about 10% of the transmission signal. S-OH
Indicates a reproduction section overhead (hereinafter, referred to as RS-OH), a multiplex section overhead (hereinafter, MS-OH).
Described). RS-OH is used for performing frame synchronization, error monitoring, and the like in R-REP and LT-MUX. The MS-OH is used in the LT-MUX to perform system redundancy switching, error monitoring, and the like. S
In the DH transmission system, the R-REP processes the upper three lines (RS-OH) of the S-OH in the STM frame, and
The T-MUX processes all nine lines of the S-OH (RS-OH + MS-OH) in the STM frame.

In recent years, a linear repeater (hereinafter, L-REP) that amplifies light without converting an input signal into an electric signal.
Has been developed. L-REP has a function of amplifying an optical signal as it is, and compensates only for attenuation of the optical signal caused by being transmitted in an optical fiber (for example,
Hagimoto, Aoyama: Relay transmission system using an optical fiber amplifier, IEICE Transactions B-1, Vol. 75-B
-1, No. 5, p. 246, 1992). As shown in FIG. 3, by using the L-REP instead of the R-REP, the playback section interval can be greatly extended. Since L-REP amplifies an optical signal as it is, it is not affected by signal speed or conversion format. Therefore, the reproduction section shown in FIG. 3 also becomes a flexible transmission path which is not influenced by the signal speed and the modulation format.

[0005] In the configuration of FIG.
Communication quality may deteriorate due to a failure or the like. SD
In the H transmission system, the R-RE detecting the deterioration of the communication quality
P indicates the situation and its own REP number (hereinafter REP-I
D) is sent to the downstream LT-MUX. This is called fault location. CCITT G. In 783, RS-O
Recommendations are made for fault location in SDH transmission systems based on the F1 byte of H. CCITT G. FIG. 4 shows the bit assignment of the F1 byte of the RS-OH defined by the standard 783. The F1 byte is 8 bits, and the first bit is represented as b1, and the last bit is represented as b8. b1 and b2 are “communication qualities” of the reproduction section detected by the R-REP, and b3 to b8 indicate REP-ID. “Communication quality” is divided into four stages as shown in FIG. 4. In a normal state, “00” is output, and priority processing is performed according to the degree of deterioration of communication quality. “10” (REC) has the highest priority processing, followed by “01” (MAJERR), followed by “11” (ERRMON), and “00” (Normal) has the lowest priority processing. is there. Also, there is a priority process based on the same alarm, and “later” has a higher priority than “earlier”. The functions of the F1 byte described above are shown in FIGS.

[0006]

The R-REP F
The fault locating function using one byte has been described. But,
L-REP, which is a non-regenerative repeater, has no equivalent function. In a configuration as shown in FIG. 3 in which 50 L-REPs are connected in series, if one of the L-REPs fails, 50
All of the devices will be checked. Actually, L-
Since the REP will be installed at a distance of several tens of kilometers, the time and operation required for the inspection will be enormous.

[0007] In the F1 byte of the R-REP, "communication quality" indicates "input disconnection (frame disconnection)", "error occurrence above threshold", "error occurrence below threshold", and "normal". It is represented in four stages. Analog information that can be monitored by L-REP (for example, L-REP using an optical fiber amplifier)
Then, input optical power, output optical power, noise figure, pump light LD
By monitoring the current, pumping light power, internal gain, internal loss, S / N, etc.) and setting a threshold value, it is possible to detect a signal similar to "communication quality" detected by R-REP (hereinafter referred to as "communication quality"). , These are referred to as “operation information”). However, L-RE
The “operation information” detected by P is not always equal to the “communication quality” detected by the digital transmission device on the downstream side.

If the threshold value of the analog information is set high, even if the digital transmission device on the downstream side detects the deterioration of the communication quality, the analog information is lower than the threshold value. The section may not be located. Conversely, if the analog information detection threshold is set low, the digital electrical equipment on the downstream side does not detect the deterioration of the communication quality, but the line with the normal L-REP indicates “abnormal operation information”. May be notified to a monitoring device or a maintenance person. For example, when the L-REP detects the deterioration of the operation information and notifies the maintenance person that the operation information is out of order, there is a danger that a normally operating transmission line may be disconnected by replacing the L-REP.

[0009]

In order to solve the above problems, the method of the present invention uses LT-MUX, R-REP, and L-REP.
-An REP or the like, and an optical transmission line including a main signal line and a supervisory line, which are composed of an optical fiber or the like connecting them, are provided with LT-MUX or R-REP at both ends, and a plurality of L- It is divided into a plurality of sections in which the REP is inserted, and in each section, the LT-MUX on the downstream side is transmitted by alarm transfer using the upstream and downstream monitoring lines.
Or, the communication failure detected by the R-REP is compared with the content of the failure detected by each L-REP, and if there is a correlation, the corresponding L-REP is located on the downstream LT-MUX or R-REP, The L-REP is a method for monitoring an optical transmission line, characterized by displaying and / or notifying a monitoring device to which the own device is connected. In this way, the "communication quality"
By performing a correlation process between the "operation information" and the "operation information", the ambiguity of the "operation information" can be eliminated.

Further, according to the present invention, the L-REP has operation information detecting means for detecting a change in a main signal transmission state caused by a failure, and the LT-MUX or the R-REP has a communication quality included in the main signal. LT-MUX, RR having communication quality detection means for detecting communication quality from a code for detection.
Either EP or L-REP compares communication quality information detected by the communication quality detection means with operation information detected by the operation information detection means, and determines a correlation between the communication quality information and the communication failure determination means. When the communication failure determining means determines that there is a correlation between the communication quality information and the operation information, the monitoring line is used to notify at least the corresponding L-REP that a communication failure has occurred. And a communication failure notifying means for monitoring the optical transmission path.

The present invention will be specifically described with reference to FIG. FIG. 6A shows a general transmission system, in which the left side of the figure is the E side (upstream side) and the right side of the figure is the W side (downstream side). Also, between L-REP or between L-REP and R-RE
A monitoring line (LSV) different from the main signal line is provided between Ps. R-REP # 1,5 can be replaced with LT-MUX. In the present invention, the "operation information" detected by the L-REP itself is compared with the "communication quality" detected by the downstream R-REP or the LT-MUX. A specific device for performing the comparison is L-REP or R-REP (LT-MU).
X).

First, the case where the L-REP performs comparison will be described. In FIG. 6B, the “communication quality” detected by the R-REP # 5 is determined by using the LSV of the W
Notifying P. When "operation information" is detected by L-REP and "communication quality" is detected by R-REP # 5 on the downstream side, each L-REP is notified of "communication quality" of R-REP # 5. Therefore, comparison with the “operation information” of self-detection is performed. When there is a correlation, as shown in FIG.
To the downstream R-REP # 5. In addition, each LR
The notification to the monitoring device connected to the EP and the notification to the person handling the own device by turning on the FAIL lamp are performed.

Next, the case where the R-REP performs comparison will be described. "Operation information" is detected by L-REP, and FIG.
As shown in (c), the downstream R-REP # 5 is notified by LSV. In the R-REP # 5, the "communication quality" detected by the R-REP # 5 is compared with the L-REP "operation information" notified by the LSV. When there is a correlation, FIG.
As described above, the LSV notifies that the corresponding L-REP is correlated. The notification to the monitoring device connected to the L-REP and the notification to the person handling the own device by turning on the FAIL lamp are performed.

[0014]

According to the present invention, when a communication failure occurs due to an L-REP or an L-REP section in a reproduction section including an L-REP and a multiplex section including the reproduction section, accurate fault localization is performed. Can be.

[0015]

[Embodiment] FIG. 7 shows a first embodiment of the present invention in which a comparison is made with each L-REP, and is described. FIG. 7 is a configuration diagram of an SDH transmission system including L-REP. A monitoring line (LSV) different from the main signal line is provided between L-REP or between L-REP and R-REP. In FIG. 7, R-REP
Can be replaced with LT-MUX.

FIG. 7 (a) shows each LR from R-REP # 1.
A state in which “communication quality” is notified to the EP is shown. SD
The H-compatible R-REP monitors the communication quality, and transfers the result to the upstream using the F1 byte. If two bits indicating the communication state of the F1 byte are notified to each L-REP, the “operation information” detected in each L-REP and the downstream R-REP are transmitted.
Can be compared with the "communication quality" detected in step (1). As shown in FIG. 7B, L-REP # 3 detects the deterioration of the “operation information”, and the F-REP notified to each L-REP.
If the two bits indicating the 1-byte communication state indicate that there is an error, an input disconnection (frame disconnection), or the occurrence of an error equal to or greater than a threshold, L-REP # 3 is determined to be correlated.

As shown in FIG. 7 (c), L-REP # 3, which is determined to have a correlation, degrades the operation information toward the downstream side and
-Send together with the REP number. With the R-REP, the L-REP that causes the degradation of the communication quality detected by the user can be reliably grasped. In L-REP, F
When the AIL lamp is turned on, a maintenance person staying at the L-REP installation location can be notified of the situation.

Such a system according to the present invention uses the LT-M
UX or R-REP detects communication quality from a code for detecting communication quality included in the main signal, and transmits communication quality information detected by the communication quality detecting means upstream using the monitoring line. Communication quality information notifying means for notifying the L-REP of the side, the operation information detecting means for detecting a change in the main signal transmission state caused by the failure, and the communication quality information detecting means detecting the change in the L-REP. A communication failure determining unit that compares the communication quality information with the operation information detected by the operation information detecting unit and determines a correlation between the communication quality information and the operation information detected by the operation information detecting unit; When it is determined that a communication failure has occurred, the LT-MUX or R-REP on the downstream side is
And a communication failure notifying means for notifying the user. According to the present invention, it is possible to eliminate the ambiguity of the “operation information” detected by the L-REP, and perform a reliable fault location and maintenance action.

FIG. 8 shows a second embodiment in which a comparison is made with the R-REP according to the present invention. Here, only portions different from the first embodiment will be described. As shown in FIG.
When REP # 3 detects the deterioration of “operation information”, FIG.
(A) As shown in FIG.
The REP number is transmitted together. In R-REP # 1,
The “operation information” detected by the L-REP is compared with the “communication quality” detected by the own device. L-REP # 3 detects the deterioration of the "operation information", and the "communication quality" detected by R-REP # 1 indicates any of an error, input loss (frame loss), and occurrence of an error equal to or greater than the threshold. If, R-RE
P # 1 is determined to be correlated. FIG. 8B shows R-REP.
FIG. 11 shows a state in which “correlation exists” is reported from # 1 to L-REP # 3. When the FAIL lamp is turned on as shown in FIG. 8C, L-REP # 3 can notify a maintenance person staying at the L-REP installation location of the situation.

Such a system according to the present invention is an L-RE
P is an operation information detecting means for detecting a change in a main signal transmission state caused by a failure, and operation information detected by the operation information detecting means is transmitted to the downstream LT-MUX using the monitoring line.
Or an operation information notifying unit for notifying the R-REP,
LT-MUX or R-REP detects communication quality from a code included in the main signal for detecting communication quality, communication quality detection means, communication quality information detected by the communication quality detection means, and operation information detection A communication failure determining unit that compares the operation information detected by the communication unit with the operation information and determines a correlation between the communication quality information and the operation information if the communication quality determination unit determines that the communication quality information and the operation information have a correlation; At least the corresponding L-RE is notified by using the monitoring line that a failure has occurred.
Communication failure notification means for notifying P. According to the present invention, it is possible to eliminate the ambiguity of the “operation information” detected by the L-REP, and perform a reliable fault location and maintenance action.

Embodiments 1 and 2 show the operation when one L-REP section becomes a failure in the reproduction section. Since the L-REP is an analog amplifier, if an abnormality such as input optical power, output optical power, and S / N occurs in a certain L-REP, the L-REP on the downstream side may be affected. For example, in a transmission line in which a plurality of L-REPs for performing constant gain control are connected, when an optical fiber loss in a certain section increases, the L-REP detects a decrease in input power. In the L-REP that performs constant gain control, a decrease in input power results in a decrease in output power. That is, all the L-REPs downstream of the faulty optical fiber detect a drop in input power.

In this case, the target L-REP is the most upstream L-REP. In the regeneration section, a monitoring method for evaluating the L-REP on the most upstream side is disclosed in Japanese Patent Application No. 5-427.
No. 62. In this method, the “operation information detected by L-REP itself” according to the method of the present invention is used.
When the method "comparison with the communication quality" detected by the downstream R-REP or the LT-MUX is used together, a reliable failure evaluation and maintenance action can be performed even in the above-mentioned spread situation.

FIG. 9 shows a case where such a situation occurs.
A method for performing comparison using L-REP described in the first embodiment will be described. FIG. 9A shows the case where RR is used as described in the first embodiment.
A situation is shown in which the current communication quality of the main signal transmission path WE where EP # 1 is terminated is notified to each L-REP using the F1 byte. FIG. 9B shows R-REP # 5 and L-REP # 5.
This shows a case where all the L-REPs # 2 to 4 have detected operation information due to a failure section of REP # 4. Each L-RE
P compares the communication quality based on the passed F1 byte with the operation information of self-detection. If it is determined that each L-REP has a correlation, as shown in FIG. 9C, the L-REP sends the operation information and the L-REP number together toward the downstream side.

Further, each L-REP detects whether operation information is coming from the upstream side, and determines whether or not to transfer the operation information by self-control, thereby performing upstream priority processing. In FIG. 9C, the L-REP # 4 transfers the operation information to the downstream side because no operation information has been received from the upstream R-REP # 5.
In P # 3, since the operation information has been received from the L-REP # 4 on the upstream side, the transfer process is stopped (INH state) regardless of whether the operation information is already being transferred to the downstream side.
Similarly, since the L-REP # 2 is also set to the INH state, only the operation information of the L-REP # 4 is detected at the terminal point R-REP # 1. Also, FAIL at L-REP
When the lamp is turned on, a maintenance person staying at the L-REP installation location can be notified of the situation. From the above, R-
In REP # 1, it is possible to locate the L-REP closest to the failure section.

FIG. 10 shows a method of performing comparison by R-REP described in the second embodiment when the same situation as in FIG. 9 occurs. FIG. 10A shows a case where all the L-REPs # 2 to 4 have detected the operation information in the failure section of the R-REP # 4. There are two methods for giving priority to the upstream side of L-REPs # 2 to # 4. One is each L-RE, as in FIG.
This is a method in which P detects whether or not operation information is coming from the upstream side and determines whether or not to transfer the operation information by self-control. The other is a method in which the R-REP # 1 knows the connection state of the L-REP and performs the upstream priority processing based on the operation information received from the L-REPs # 2 to # 4. . In either case, upstream priority processing is possible. In FIG. 10B, in the R-REP # 1, the "operation information" detected by the L-REP on the most upstream side is compared with the "communication quality" detected by the own device. FIG.
The figure shows a state in which "REP # 1" notifies L-REP # 4 of "correlation exists". If the FAIL lamp is turned on in L-REP # 4, it is possible to notify the maintenance person staying at the L-REP installation location of the situation. From the above, RR
In EP # 1, it is possible to locate the L-REP closest to the failed section.

In the specification of Japanese Patent Application No. 5-42762, in a multiplex section in which a plurality of reproduction sections are connected,
It describes fault location using the F1 byte. When a failure occurs in the L-REP section in the playback section, the R-REP terminating the playback section is transmitted to the downstream LT-M.
Transfer F1 byte to UX. At this time, the REP-I of the L-REP that has detected the failure is in the REP-ID of the F1 byte.
This is a method of writing D (ID rewriting process of F1 byte). By this method, the state of the playback section where the communication quality has deteriorated and the L-REP closest to the faulty section causing the situation
Can be located. In addition to this method, the method of "comparison" operation information "detected by L-REP itself with" communication quality "detected by downstream R-REP or LT-MUX" is used. Then, in the multiplex section in which a plurality of reproduction sections are connected, the fault location can be reliably performed from the LT-MUX using the F1 byte.

FIG. 11 shows the LR in the multiplex section.
A failure occurs between EP # 3 and L-REP # 4 and RR
The case where deterioration of communication quality is detected in EP # 1 is shown.
Hereinafter, a method of performing comparison using R-REP described in the second embodiment will be described. A method of performing comparison using L-REP described in the first embodiment is also possible. As shown in FIG.
-REP # 3 indicates that R-REP # 1 has degraded operation information and L
-Transfer with the REP number. R-REP # 1 is
The communication quality of self-detection is compared with the operation information of L-REP # 3 to determine the correlation. As shown in FIG.
The REP # 1 transfers the F1 byte describing the communication quality of self-detection and the ID number of the L-REP # 3 to the LT-MUX. Also, since "correlation exists" is notified from R-REP # 1 to L-REP # 3, L-REP # 3 can turn on the FAIL lamp and notify the maintenance person staying at the L-REP installation location of the situation. be able to. In LT-MUX # 0,
From the F1 byte, the status of the playback section where the communication quality has deteriorated and the ID of the L-REP closest to the faulty section that is the cause
You can know.

FIG. 12 shows a fifth embodiment in which a comparison is made by the operation system according to the present invention, which will be described. FIG.
Is a configuration diagram of an SDH transmission system including L-REP, and shows only one direction. The monitoring center has an operation system. A monitoring line different from the main signal line is provided between the L-REP and the monitoring center or between the R-REP and the monitoring center. R-REP in FIG. 12 is LT
-Can be replaced with MUX.

FIG. 12A shows "communication quality" from each R-REP # 1, # 5 to the monitoring center.
A state in which “operation information” is notified from # 2, # 3, and # 4 to the monitoring center is shown. The R-REP corresponding to the SDH monitors the communication quality, and transfers the result to the downstream side in the F1 byte. By notifying the monitoring center of the two bits indicating the communication state of the F1 byte, comparison with the “operation information” detected by each L-REP can be performed. As shown in FIG. 12B, L-REP # 4 detects the deterioration of the “operation information”,
If the two bits indicating “communication quality” detected by R-REP # 5 on the downstream side are one of an error, an input disconnection (frame disconnection), and an error occurrence equal to or more than a threshold value, the monitoring center performs the correlation. Judge that there is. At the monitoring center, the downstream R
LR detected by REP causing deterioration of communication quality
EP can be grasped reliably. FIG.
When the FAIL lamp is turned on by the L-REP as in (c), the situation can be notified to the maintenance person staying at the L-REP installation location.

According to the system of the present invention, a monitoring center is further provided in the optical transmission line, and the L-REP detects operation information detecting means for detecting a change in the main signal transmission state caused by a failure; Means for notifying the monitoring center of the operation information detected by the means to the monitoring center by using the monitoring line, wherein the LT-MUX or the R-REP uses a code for detecting communication quality included in the main signal. Communication quality detection means for detecting communication quality, and communication quality information notification means for notifying the monitoring center using the monitoring line communication quality information detected by the communication quality detection means, the monitoring center, A communication failure determination unit that compares the communication quality information detected by the communication quality detection unit with the operation information detected by the operation information detection unit and determines a correlation therebetween; L-REP at least corresponding with the monitoring circuit that communication failure has occurred when it is determined that there is a correlation in the communication quality information and said operating information
And a communication failure notifying means for notifying the user.

[0031]

As described above, since the L-REP merely amplifies the main signal in an analog manner, the L-REP is not used.
There is a possibility that the operation information detected by the above does not match the digital communication quality detected by the R-REP / LT-MUX that terminates the digital signal on the downstream side. By correlating the operation information detected by the L-REP with the digital communication quality detected by the R-REP / LT-MUX, the L-REP
Can eliminate the ambiguity of the detected operation information, and perform reliable fault locating and maintenance actions. Also, by combining the upstream priority processing of the reproduction section according to the invention of Japanese Patent Application No. 5-42762 and the F1 byte ID rewriting processing by the R-REP, the LT-MUX starts converting the F1 byte into the reproduction section having deteriorated communication quality from the F1 byte. It is possible to know the situation and the ID of the L-REP closest to the faulty section that is the cause.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a general transmission system.

FIG. 2 shows a configuration of a frame.

FIG. 3 is a diagram illustrating a configuration of a transmission system when a linear repeater is inserted.

FIG. 4 shows CCITTG. RS-OH defined in 783
Is a configuration of the bit assignment of the F1 byte.

FIG. 5 shows priorities in the contents of the b1 and b2 bits of the F1 byte.

FIG. 6 is a diagram illustrating the principle of the present invention.

FIG. 7 is a diagram illustrating a first embodiment in which a correlation is obtained by L-REP itself.

FIG. 8 is a diagram illustrating a second embodiment in which a correlation is obtained by R-REP.

FIG. 9 is a diagram illustrating a third embodiment in which, when motion information is detected by a plurality of L-REPs, a correlation is obtained by the L-REP itself.

FIG. 10 is a diagram illustrating a third embodiment in which, when motion information is detected by a plurality of L-REPs, a correlation is obtained by an R-REP.

FIG. 11 is a diagram illustrating a fourth embodiment for performing fault localization in a plurality of linear relay sections.

FIG. 12 is a diagram illustrating a fifth embodiment in which a correlation is obtained by a monitoring center.

[Explanation of symbols]

 LT-MUX Multiplexing terminal equipment R-REP regeneration repeater L-REP linear repeater RS-OH regeneration section overhead MS-OH multiplex section overhead REP-ID regeneration repeater number

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukio Kobayashi Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo (56) References JP-A-5-2922083 (JP, A) 59-175233 (JP, A) JP-A-5-292040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14 / 08 H04B 17/02

Claims (14)

(57) [Claims] The present invention relates to a multiplexing terminal and a multiplexing terminal, a regenerative repeater for reproducing and outputting a main signal and a multiplexing terminal, or a regenerative repeater and a regenerative repeater. An optical transmission line monitoring system to which one or more linear repeaters for amplifying and outputting the main signal without reproducing the main signal are connected, wherein the optical transmission line transmits the main signal. A main signal line and a monitoring line for transmitting and receiving communication failure information, wherein the linear amplifier has an operation state detecting means for detecting a change in the main signal transmission state, and detects a change in the detected operation state. The information is sent to the regenerative repeater or the multiplexing terminal device located on the downstream side as operation information via the monitoring line, and the regenerative repeater and the multiplexing terminal device detect communication quality information from the received main signal. Means and sent from the linear amplifier over the supervisory line It has fault determining means for comparing the operation information with the communication quality information detected by itself and determining a correlation between these pieces of information, and fault notifying means for notifying the linear repeater of the occurrence of a communication fault via the monitoring line. The regenerative repeater or multiplexing terminal device determines that a communication failure has occurred when a correlation is found between the communication quality information and the operation information, and has transmitted the operation information indicating that the failure has occurred. A monitoring system for an optical transmission line, wherein a notification is sent to a linear repeater. 2. The optical transmission line monitoring system according to claim 1, wherein the linear repeater has means for displaying occurrence of a communication failure, and the transmission from the multiplexing terminal device or the regenerative repeater. A monitoring system for an optical transmission line, which displays the occurrence of a failure when receiving the received failure occurrence notification. 3. The optical transmission line monitoring system according to claim 1, wherein the linear repeater sends its own identification number together with the operation information to the regenerative repeater or the multiplexing terminal device via a monitoring line. A monitoring system for an optical transmission line, wherein a transmitting / regenerating repeater or a multiplexing terminal device locates a fault location from an identification number of a linear repeater sent together with operation information. 4. The optical transmission line monitoring system according to claim 3, wherein the regenerative repeater or the multiplexing terminal device receives the plurality of pieces of operation information at substantially the same time, and the linear repeater located at the most upstream side. A monitoring system for an optical transmission line, characterized by comparing operation information from a device with notification quality information detected by the device itself to locate a failure point. 5. The optical transmission line monitoring system according to claim 1, wherein the regenerative repeater detects the operation information sent from the linear repeater on the upstream side and the self repeater. If there is a correlation between the communication quality information and the communication quality information, the identification number of the linear repeater that transmitted the operation information and the communication quality detected by the communication device are transmitted to the multiplexing terminal equipment located on the downstream side. An optical transmission line monitoring system characterized by the following. 6. A multiplexing terminal device, a regenerative repeater for reproducing and outputting a main signal and a multiplexing terminal device, or a regenerative repeater and a regenerative repeater. An optical transmission line monitoring system to which one or more linear repeaters for amplifying and outputting the main signal without reproducing the main signal are connected, wherein the optical transmission line transmits the main signal. The regenerative repeater and the multiplexing terminal device have means for detecting the communication quality from the received main signal, and the main signal line and the monitoring line for transmitting and receiving the communication failure information are detected. Sending the communication quality information to a linear repeater located on the upstream side via a monitoring line, the linear amplifier comprising: an operating state detecting means for detecting a change in a main signal transmission state; and the regenerative repeater or multiplexing terminal. The communication quality information sent from the device via the The linear repeater has a correlation between the communication quality information and the operation information detected by the communication repeater. A monitoring system for an optical transmission line, wherein when it is recognized, it is determined that a failure has occurred. 7. The optical transmission line monitoring system according to claim 6, wherein the linear repeater has display means for displaying the occurrence of a fault, and when the fault is determined to have occurred, the fault is generated. An optical transmission path system characterized by displaying: 8. The optical transmission line monitoring system according to claim 6, wherein the linear repeater notifies the downstream multiplexing terminal device or the regenerative repeater of the occurrence of a failure via the monitoring line. A monitoring system for an optical transmission line, comprising: a failure notifying unit for notifying. 9. The optical transmission line monitoring system according to claim 8, wherein the linear repeater does not detect a failure occurrence notification from the upstream linear repeater when determining that a failure has occurred. The fault information determined by itself is notified to the downstream multiplexing terminal equipment or regenerative repeater, and the occurrence of the fault is displayed.If the fault occurrence notification from the upstream linear repeater is detected, the fault information is sent to the downstream side. A monitoring system for an optical transmission line, which does not notify the multiplexing terminal device or the regenerative repeater and does not indicate the occurrence of a failure. 10. A multiplexing terminal device, a multiplexing terminal device, a regenerative repeater for reproducing and outputting a main signal and a multiplexing terminal device, or a regenerative repeater and a regenerative repeater. A monitoring system for an optical transmission line system in which one or a plurality of linear repeaters for amplifying and outputting a main signal without reproducing the main signal line are connected via a main signal line. Comprises a monitoring line connecting a monitoring center with a linear repeater, a regenerative repeater, and a multiplexing terminal device, wherein the linear repeater has a transmission state of a main signal transmitted via a main signal line. Multiplexed terminal equipment and a regenerative repeater have a means for detecting communication quality from a received main signal. Sends the detected quality information to the monitoring center, A center for comparing the operation information transmitted from the linear repeater with the quality information transmitted from the multiplexing terminal device or the regenerative repeater, and determining a correlation between these pieces of information; A failure notifying unit that notifies a linear repeater of the occurrence of a communication failure via a monitoring line, and determines that a failure has occurred if a correlation is found between the communication quality information and the operation information. An optical transmission line monitoring system for notifying the occurrence of a failure to the linear repeater that has transmitted the operation information. 11. A monitoring system for an optical transmission line according to claim 10, wherein said linear repeater sends its identification number together with operation information to a monitoring center via a monitoring line,
A monitoring system for an optical transmission line, wherein the monitoring center locates a fault location from the identification number of the linear repeater sent together with the operation information. 12. The monitoring system for an optical transmission line according to claim 11, wherein when the monitoring center determines that a communication failure has occurred, the monitoring center transmits the operation information used for the determination via the monitoring line. A monitoring system for an optical transmission line, which notifies a sending linear repeater of the occurrence of a communication failure. 13. The optical transmission line monitoring system according to claim 12, wherein the linear repeater has display means for displaying the occurrence of a fault, and when receiving a notification of the fault occurrence from the monitoring center, An optical transmission line monitoring system for displaying occurrence of a fault. 14. The monitoring system for an optical transmission line according to claim 1, wherein the regenerative repeater or the multiplexing terminal device is a CCITT G.100. 707,
An optical transmission line monitoring system corresponding to the synchronous interface recommended in 708 and 709, wherein the communication quality information is configured as an F1 byte defined by the synchronous interface or a part of the F1 byte. .