JPH07240715A - Method and system for monitoring optical transmission line - Google Patents

Abstract

PURPOSE:To provide the method and the system which monitor an optical transmission line including linear repeaters with a high precision by displaying or reporting correlations of a communication fault, which a regenerative repeater on the downstream side or a multiplexing terminal station device detects by alarm transfer using incoming and outgoing monitor lines, by the linear repeater. CONSTITUTION:In the figure, the left is the E side (upstream side), and the right is the W side (downstream side). A monitor line (LSV) other than a main signal line is provided between L-REPs (linear repeaters) or between the L-REP and an R-REP (regenerative repeater). Operation information detected by the L-REP itself ana the communication quality detected by the REP on the downstream side or an LT switch MUX (multiplexing terminal station device) are compared with each other. The LSV between the w side and the E side is used to report the communication quality detected by the L-REP #5 to each L-REP. Operation information is detected in the L-REP, and the communication quality is detected by the REP #5 on the downstream side and is compared with operation information. If correlations are detected, they are reported to the R-REP #5 on the downstream side by the LSV. They are reported or displayed to a monitor device connected to each L-REP. The same operation is performed for R-REP.

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 regenerator, a linear repeater, etc., and an optical fiber connecting them, and having a main signal line and a supervisory line. The present invention relates to a transmission line monitoring method and a monitoring system.

[0002]

2. Description of the Related Art A general digital relay transmission system is shown in FIG. A 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. 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 interferences (attenuation, waveform distortion, noise, etc.) from the optical fiber. A regenerative repeater (hereinafter, referred to as R-REP) is used to remove these and increase the distance between the LT and the MUX. R-REP
Has functions such as optical-electrical conversion, electric-optical conversion, equivalent amplification, retiming extraction, and identification reproduction. An optical signal that is attenuated and distorted by being transmitted through an optical fiber
It is reproduced and output by the R-REP function.

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 the SDH transmission system since 1989. This SDH transmission system realizes the configuration shown in FIG. As shown in FIG. 1, R-RE
Between P or between LT-MUX and R-REP is called a regenerator section (= playback section), and between LT and MUX is called a multiplex section (= multiplex section). In the SDH transmission system, both low and high speed signals are shown in FIG.
The STM (Synchronons Transport Module) frame shown 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, hereinafter referred to as S-OH) which is approximately 10% of the transmission signal. S-OH
Is a reproduction section overhead (hereinafter referred to as RS-OH), multiple section overhead (hereinafter referred to as MS-OH).
It is categorized as). RS-OH is used for frame synchronization, error monitoring, etc. in R-REP and LT-MUX. The MS-OH is used in the LT-MUX to perform system redundancy system switching, error monitoring, and the like. S
In the DH transmission system, the R-REP processes the upper three rows (RS-OH) of the S-OH in the STM frame, and the L-REP
In T-MUX, all 9 rows (RS-OH + MS-OH) of S-OH in the STM frame will be processed.

In recent years, a linear repeater (hereinafter referred to as an L-REP) that amplifies an optical signal as it is without converting the input signal into an electric signal.
Has been developed. The L-REP 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 (for example,
Hagimoto, Aoyama: Relay transmission system using optical fiber amplifier, IEICE Transactions B-1, Vol. 75-B
-1, No. 5, p246, 1992). As shown in FIG. 3, by using L-REP instead of R-REP, the reproduction section interval can be greatly extended. Since L-REP amplifies an optical signal as it is, it does not depend on the signal speed and conversion format. Therefore, the reproducing section shown in FIG. 3 is also a flexible transmission line that is not affected by the signal speed and the modulation format.

In the configuration of FIG. 1, the cable breaks and the R-REP
Communication quality may deteriorate due to a failure or the like. SD
In the H transmission system, the R-RE that detects the deterioration of communication quality
P is the situation and its own REP number (hereinafter REP-I
(Denoted as D) is notified to the downstream LT-MUX. This is called fault location. CCITT G. In 783, RS-O
It recommends fault location of SDH transmission system based on F1 byte of H. CCITT G. FIG. 4 shows the bit assignment of the F1 byte of RS-OH defined by 783. The F1 byte has 8 bits, and the first bit is represented by b1 and the last bit is represented by b8. b1 and b2 are the "communication quality" of the reproduction section detected by R-REP, and b3 to b8 are REP-IDs. The "communication quality" is divided into four stages as shown in FIG. 4, "00" is output in a normal state, and priority processing is performed according to the degree of deterioration of communication quality. “10” (REC) has the highest priority processing, “01” (MAJERR) has the next highest, “11” (ERRMON) follows, and “00” (Normal) has the lowest priority processing. is there. In addition, there is priority processing with the same alarm, and "late start" has a higher priority than "first start." The functions of the F1 byte described above are shown in FIGS.

[0006]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
The fault location function using 1 byte has been explained. But,
The L-REP, which is a non-regenerative repeater, has no corresponding function. In the configuration shown in FIG. 3 in which 50 L-REPs are connected in series, if one of them fails, 50
All equipment will be inspected. In fact, L-
Since the REP will be installed at a place several tens of kilometers away, the time and operation required for inspection will be enormous.

In the F1 byte of R-REP, "communication quality" is set to "input loss (frame loss)", "error occurrence above threshold value", "error occurrence below threshold value", or "normal". It is expressed in four stages. Analog information that L-REP can monitor (for example, L-REP using an optical fiber amplifier
Then, input optical power, output optical power, noise figure, pumping light LD
By monitoring the current, pumping light power, internal gain, internal loss, S / N, etc.) and setting the threshold value, it is possible to detect something similar to the “communication quality” detected by the R-REP (hereinafter, “communication quality”). , And these are called “motion information”). However, L-RE
The "operation information" detected by P is not necessarily equal to the "communication quality" detected by the downstream digital transmission device.

When the threshold value of analog information is set high, even if the deterioration of the communication quality is detected by the digital transmission apparatus on the downstream side, the analog information is below the threshold value, so that the communication failure has occurred in the L-REP. There is a possibility that the section cannot be located. On the contrary, if the analog information detection threshold value is set to be low, even if the downstream digital electric device does not detect the deterioration of the communication quality, the line with normal L-REP is set as “abnormal operation information”. There is a possibility of notifying the monitoring device and maintenance personnel. For example, when the L-REP detects the deterioration of the operation information and notifies the maintenance person that there is a failure, there is a risk that the normally operating transmission path is disconnected due to the L-REP exchange.

[0009]

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

Further, according to the present invention, the L-REP has operation information detecting means for detecting a change in the main signal transmission state caused by a failure, and LT-MUX or R-REP includes communication quality included in the main signal. The communication quality detecting means for detecting the communication quality from the code for detection is provided, and LT-MUX, RR
Either EP or L-REP is 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 the correlation. If the communication failure determining unit determines that the communication quality information and the operation information have a correlation, at least the corresponding L-REP is notified using the monitoring line that a communication failure has occurred. And a communication failure notifying means for operating the optical transmission line.

The present invention will be specifically described with reference to FIG. FIG. 6A shows a general transmission system, where 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 and 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 LT-MUX. The specific device for comparison is L-REP or R-REP (LT-MU.
Either X) is acceptable.

First, the case where the L-REP performs the comparison will be described. In FIG. 6B, the "communication quality" detected by the R-REP # 5 is calculated using the LSV of the W-E.
P is notified. When the "operation information" is detected by the L-REP and the "communication quality" is detected by the downstream R-REP # 5, each L-REP is notified of the "communication quality" of the R-REP # 5. Therefore, a comparison is made with the "motion information" of self-detection. If there is a correlation, as shown in FIG.
To notify the downstream R-REP # 5. Also, each L-R
The monitoring device connected to the EP is notified, and the person handling the device is notified by turning on a FAIL lamp.

Next, the case where the R-REP performs the comparison will be described. The "motion information" is detected by the L-REP, and FIG.
As in (c), the downstream R-REP # 5 is notified by LSV. The R-REP # 5 compares the "communication quality" detected by the R-REP # 5 with the L-REP "operation information" notified by the LSV. If there is a correlation, FIG. 6 (b)
As described above, the LSV notifies that there is a correlation with the corresponding L-REP. The L-REP is notified to the connected monitoring device, and the person handling the device is notified by turning on the FAIL lamp.

[0014]

According to the present invention, when a communication failure due to the L-REP or the L-REP section occurs in the reproduction section including the L-REP and the multiple section including the reproduction section, accurate fault location is performed. You can

[0015]

EXAMPLE Example 1 in which comparison is made with each L-REP according to the present invention is shown in FIG. 7 and will be 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 the L-REP or between the L-REP and the R-REP. In FIG. 7, R-REP
Can be replaced with LT-MUX.

FIG. 7A shows each L-R from R-REP # 1.
It shows how to notify the "communication quality" to the EP. SD
The H-compatible R-REP monitors the communication quality and transfers the result in the F1 byte to the upstream side. If 2 bits indicating the communication status of this F1 byte are notified to each L-REP, the "operation information" detected by each L-REP and the downstream R-REP
It is possible to make a comparison with the "communication quality" detected in. As shown in FIG. 7B, the L-REP # 3 detects the deterioration of the “motion information”, and is notified to each L-REP.
If the two bits indicating the communication state of one byte indicate that there is an error, an input disconnection (frame disconnection), or an error above the threshold, L-REP # 3 determines that there is a correlation.

The L-REP # 3 judged to have the correlation has the deterioration of the operation information and the L-value toward the downstream side as shown in FIG. 7 (c).
-Send together the REP number and send. The R-REP can surely grasp the L-REP that causes the deterioration of the communication quality detected by itself. In addition, F in L-REP
When the AIL lamp is turned on, it is possible to notify the maintenance person staying at the L-REP installation place of the situation.

The system of the present invention as described above is used in the LT-M.
The UX or R-REP uses the communication quality detecting means for detecting the communication quality from the code for detecting the communication quality included in the main signal, and the 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 on the side, and the L-REP detecting operation information detecting means for detecting a change in the main signal transmission state caused by a failure, and the communication quality detecting means. There is a correlation between the communication quality information and the operation information by the communication failure determination means for comparing the communication quality information and the operation information detected by the operation information detection means to determine the correlation. If it is determined that there is a communication failure, the monitoring line is used to determine the LT-MUX or R-REP on the downstream side.
And a communication failure notifying means for notifying. According to the present invention, it is possible to eliminate the ambiguity of the "operation information" detected by the L-REP, and perform reliable fault location and maintenance actions.

A second embodiment for comparison with the R-REP according to the present invention will be described with reference to FIG. Here, only parts different from the first embodiment will be described. As shown in FIG. 8A, L-
When REP # 3 detects the deterioration of the “motion information”, FIG.
As shown in (a), deterioration of operation information and L-
Send together with the REP number. In R-REP # 1,
The "operation information" detected by the L-REP and the "communication quality" detected by the own device are compared. L-REP # 3 detects the deterioration of "motion information", and "communication quality" detected by R-REP # 1 has an error, an input disconnection (frame disconnection), or an error occurrence above a threshold value. If it is R-RE
It is determined that P # 1 has a correlation. Figure 8 (b) shows R-REP
It shows how # 1 notifies the L-REP # 3 of "correlation". As shown in FIG. 8C, the L-REP # 3 can notify the maintenance person who stays at the L-REP installation place of the situation by turning on the FAIL lamp.

Such a system of the present invention is an L-RE
P uses the operation information detecting means for detecting a change in the main signal transmission state caused by the failure, and the operation information detected by the operation information detecting means by using the monitoring line on the downstream side of the LT-MUX.
Or an operation information notifying means for notifying the R-REP,
The LT-MUX or R-REP detects communication quality from a code for detecting communication quality included in the main signal, communication quality detecting means, communication quality information detected by the communication quality detecting means, and operation information detection. Communication failure determining means for comparing the motion information detected by the means to determine the correlation, and communication if the communication failure determining means determines that there is a correlation between the communication quality information and the motion information Using the monitoring line, at least the corresponding L-RE is informed that a failure has occurred.
Communication failure notifying 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 reliable fault location and maintenance action.

The first and second embodiments show the operation in the case where one L-REP section in the reproduction section becomes an obstacle. Since the L-REP is an analog amplifier, if an abnormality in the input optical power, the output optical power, the S / N, or the like occurs at a certain L-REP, the L-REP on the downstream side may be affected. For example, when a plurality of L-REPs that perform constant gain control are connected to a transmission path, and the 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 on the downstream side of the faulty optical fiber detect the decrease in the input power.

In this case, the target L-REP is the most upstream L-REP. In the reproduction section, a monitoring method for evaluating L-REP on the most upstream side is Japanese Patent Application No. 5-427.
62. This method is the method of the present invention, that is, "motion information detected by L-REP itself".
And the method of “comparing with the“ communication quality ”detected by the downstream R-REP or LT-MUX” are used together, it is possible to perform a reliable failure evaluation and maintenance action even in the above-mentioned spread situation.

FIG. 9 shows that when such a situation occurs,
A method of performing comparison by L-REP described in Example 1 will be described. FIG. 9A shows RR as described in the first embodiment.
The situation is shown in which the current communication quality of the main signal transmission line WE terminated by EP # 1 is notified to each L-REP using the F1 byte. FIG. 9B shows R-REP # 5 and L-REP.
This shows a case where all the L-REPs # 2 to 4 detect the motion information due to the faulty section of REP # 4. Each L-RE
P compares the communication quality of the passed F1 byte with the self-detection operation information. When it is determined that each L-REP has a correlation, as shown in FIG. 9C, the operation information and the L-REP number are sent together toward the downstream side.

Further, each L-REP can perform the upstream side priority processing by detecting whether or not the operation information is coming from the upstream side and judging whether or not to transfer the operation information by self-control. In FIG. 9C, the L-REP # 4 transfers the operation information toward the downstream side because the operation information does not come from the upstream side R-REP # 5.
In P # 3, since the operation information is received from the upstream L-REP # 4, the transfer processing is stopped (INH state) regardless of whether the operation information is already being transferred to the downstream side.
Similarly, the L-REP # 2 is also set to the INH state, so that only the operation information of the L-REP # 4 is finally detected at the termination point R-REP # 1. Also, FAIL at L-REP
By turning on the lamp, it is possible to notify the maintenance person who stays at the L-REP installation place of the situation. From the above, R-
In REP # 1, it becomes possible to locate the L-REP closest to the faulty section.

FIG. 10 shows a method of performing comparison by the R-REP described in the second embodiment when the same situation as in FIG. 9 occurs. FIG. 10A shows the case where all the L-REP # 2 to 4 detect the motion information due to the failure section of the R-REP # 4. There are two methods for prioritizing the upstream side of L-REP # 2-4. 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 the R-REP # 1 performs the upstream side priority process from the operation information received from the L-REP # 2 to 4. . Either way, upstream priority processing is possible. In FIG. 10B, in R-REP # 1, the “operation information” detected by the most upstream L-REP is compared with the “communication quality” detected by the device itself. FIG. 10C shows R
-It shows how REP # 1 notifies L-REP # 4 of "correlation". If the FAIL lamp is turned on in L-REP # 4, the situation can be notified to the maintenance person staying at the L-REP installation place. From the above, RR
In EP # 1, it becomes possible to locate the L-REP closest to the faulty 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 that terminates this playback section is the downstream LT-M.
Transfer F1 byte to UX. At this time, the REP-I of the L-REP that has detected the failure in the REP-ID of the F1 byte
This is a method of writing D (F1 byte ID rewriting process). By this method, the L-REP that is closest to the faulty section causing the situation of the playback section where the communication quality has deteriorated
It becomes possible to orient. In addition to this method, the method of “comparing“ operation information detected by L-REP itself ”with“ communication quality ”detected by downstream R-REP or LT-MUX of the present invention is also used. Then, in the multiplex section to which a plurality of reproduction sections are connected, it is possible to perform reliable fault localization from the LT-MUX using the F1 byte.

FIG. 11 shows that in multiple sections, LR
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 by the R-REP described in the second embodiment will be described. It is also possible to use the method of performing comparison by L-REP described in the first embodiment. As shown in FIG. 11A, L
-REP # 3 is the same as R-REP # 1 with deterioration of motion information and L
-Transfer together with the REP number. R-REP # 1 is
The self-detection communication quality is compared with the operation information of L-REP # 3 to determine the correlation. As shown in FIG. 11B, R-
The REP # 1 transfers the F1 byte describing the communication quality of self-detection and the ID number of L-REP # 3 to the LT-MUX. Further, since the R-REP # 1 notifies the L-REP # 3 of "correlation", the L-REP # 3 can turn on the FAIL lamp and notifies the maintenance person staying at the L-REP installation place 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.

A fifth embodiment for comparison with the operation system according to the present invention will be described with reference to FIG. 12
[Fig. 4] is a configuration diagram of an SDH transmission system including L-REP, showing only one direction. The monitoring center has an operating 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.

In FIG. 12 (a), each R-REP # 1 and # 5 notifies the monitoring center of the "communication quality", and each L-REP # 1.
It shows how # 2, # 3, and # 4 notify the monitoring center of "operation information". The SDH compatible R-REP monitors the communication quality and transfers the result in the F1 byte to the downstream side. By notifying the monitoring center of 2 bits indicating the communication status of the F1 byte, it is possible to perform comparison with the “operation information” detected by each L-REP. As shown in FIG. 12B, L-REP # 4 detects the deterioration of the "motion information",
If the 2 bits indicating the "communication quality" detected by the downstream R-REP # 5 indicate that there is an error, an input disconnection (frame disconnection), or an error above the threshold value, the monitoring center correlates. Judge that there is. Downstream R at the monitoring center
-LR that causes deterioration of communication quality detected by REP
The EP can be surely grasped. In addition, FIG.
If the FAIL lamp is turned on in the L-REP as in (c), the situation can be notified to the maintenance person staying at the L-REP installation place.

In such a 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, and the operation information detection. An operation information notifying means for notifying the monitoring center of the operation information detected by the means using the monitoring line, and the LT-MUX or the R-REP from the code for detecting the communication quality included in the main signal. The communication center includes communication quality detection means for detecting communication quality, and communication quality information notification means for notifying the monitoring center of the communication quality information detected by the communication quality detection means using the monitoring line. A communication failure determining means for comparing the communication quality information detected by the communication quality detecting means with the motion information detected by the motion information detecting means to determine the correlation; and the communication failure determining means. 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.

[0031]

As described above, since the L-REP only optically amplifies the main signal in an analog manner, the L-REP can be used.
The operation information detected in 1. may 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 motion information detected by L-REP and the digital communication quality detected by R-REP / LT-MUX, L-REP
It is possible to eliminate the ambiguity of the operation information detected by and perform reliable fault location and maintenance action. Also, by combining the upstream section priority processing of the playback section according to the invention of Japanese Patent Application No. 5-42762 and the F1 byte ID rewriting processing by R-REP, the playback section of the playback section whose communication quality has deteriorated from the F1 byte in the LT-MUX. It is possible to know the status and the ID of the L-REP closest to the faulty section that is the cause.

[Brief description of drawings]

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

FIG. 2 is a structure of a frame.

FIG. 3 is a diagram showing a configuration of a transmission system when a linear repeater is pushed in.

FIG. 4 CCITTG. RS-OH specified in 783
It is a configuration of bit assignment of the F1 byte.

FIG. 5 shows priorities in the contents of bits b1 and b2 of 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 correlation is performed by L-REP itself.

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

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

FIG. 10 is a diagram illustrating Example 3 in which correlation is detected by R-REP when motion information is detected by a plurality of L-REPs.

FIG. 11 is a diagram illustrating a fourth embodiment in which a fault is located in a plurality of linear relay sections.

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

[Explanation of symbols]

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yukio Kobayashi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (9)

[Claims] 1. A method of monitoring an optical transmission line having a main signal line and a monitoring line, which is composed of a multiplexing terminal device, a regenerator, a linear repeater, etc., and an optical fiber connecting them. The optical transmission line is divided into a plurality of sections in which multiplex terminal equipment or regenerative repeaters are located at both ends, and a plurality of linear repeaters are inserted between them. By the alarm transfer using the monitoring line, the communication failure detected by the downstream repeater or multiplexing terminal equipment is compared with the failure content detected by each linear repeater. Monitoring of an optical transmission line characterized by locating a corresponding linear repeater at a regenerative repeater or a multiplexing terminal device, and displaying and / or notifying to a monitoring device to which the own linear repeater is connected Method. 2. The linear repeater judges the correlation, and the linear repeater notified of the judgment result displays and / or notifies the monitoring device to which the own device is connected. Item 2. The optical transmission line monitoring method according to Item 1. 3. The regenerative repeater or the multiplexing terminal equipment on the downstream side judges the correlation, and the corresponding linear repeater notified of the judgment is displayed and / or displayed on the monitoring device to which the own device is connected. Alternatively, the method for monitoring an optical transmission line according to claim 1, wherein the notification is made. 4. A monitoring center is provided in the optical transmission line of each section, and a communication failure detected by a regenerator or a multiplexing terminal device on the downstream side and a failure content detected by each linear repeater are provided as a monitoring center. The linear relay which is transferred, the monitoring center judges the correlation, and which is notified of the judgment result displays and / or notifies the monitoring device to which the own device is connected. A method for monitoring the optical transmission line described. 5. A monitoring system for an optical transmission line, which comprises a multiplexing terminal device, a regenerator, a linear repeater, etc., and an optical fiber connecting them, and which has a main signal line and a monitoring line, The linear repeater has operation information detecting means for detecting a change in the main signal transmission state caused by a failure, and the regenerative repeater or the multiplexing terminal device detects the communication quality included in the main signal. Communication quality detecting means for detecting communication quality from a code, and any one of the multiplexing terminal device, regenerative repeater, or linear repeater detects the communication quality information detected by the communication quality detecting means and the operation. A communication failure determining means for comparing the operation information detected by the information detecting means to determine the correlation, and a case where the communication failure determining means determines that there is a correlation between the communication quality information and the operation information. Has a communication failure And a communication failure notifying means for notifying at least the corresponding linear repeater by using the monitoring line. 6. A monitoring system for an optical transmission line, comprising a multiplexing terminal device, a regenerator, a linear repeater, etc., and an optical fiber connecting these, and having a main signal line and a monitoring line, The regenerator or the multiplexing terminal device provides communication quality detecting means for detecting communication quality from a code for communication quality detection included in a main signal, and communication quality information detected by the communication quality detecting means. Communication quality information notifying means for notifying an upstream linear repeater using a monitoring line, the linear repeater detecting operation information detecting means for detecting a change in the main signal transmission state caused by a failure, and the communication Communication failure determination means for comparing the communication quality information detected by the quality detection means with the operation information detected by the operation information detection means to determine the correlation, and the communication failure information by the communication failure determination means. Motion information If it is determined that there is a correlation with the communication failure notifying means for notifying the regeneration repeater or the multiplexing terminal equipment on the downstream side that the communication failure has occurred, An optical transmission line monitoring system having. 7. A monitoring system for an optical transmission line, comprising a multiplexing terminal device, a regenerator, a linear repeater, etc., and an optical fiber connecting them, and having a main signal line and a monitoring line, The linear repeater uses the operation information detecting means for detecting a change in the main signal transmission state caused by a failure, and the operation information detected by the operation information detecting means by using the monitoring line on the downstream side of the regeneration repeater or A communication quality, which includes operation information notifying means for notifying the multiplexing terminal device, and wherein the regenerator or the multiplexing terminal device detects the communication quality from a code for detecting the communication quality included in the main signal. A detection means, a communication failure determination means for comparing the communication quality information detected by the communication quality detection means with the operation information detected by the operation information detection means to determine the correlation,
When the communication failure determination means determines that the communication quality information and the operation information have a correlation, at least the corresponding linear repeater is notified using the monitoring line that a communication failure has occurred. An optical transmission line monitoring system, comprising: a communication failure notifying means. 8. A monitoring system for an optical transmission line, comprising a multiplexing terminal device, a regenerator, a linear repeater, etc., and an optical fiber connecting them, and having a main signal line and a monitoring line, A monitoring center is further provided in the optical transmission line, the linear repeater detects operation information detection means for detecting a change in the main signal transmission state caused by a failure, and the operation information detected by the operation information detection means is supplied to the monitoring line. And communication means for notifying the monitoring center by using the communication information, wherein the regenerator or the multiplexing terminal device detects the communication quality from the code for detecting the communication quality included in the main signal. And a communication quality information notifying means for notifying the monitoring center of the communication quality information detected by the communication quality detecting means by using the monitoring line. A communication failure determining means for determining the correlation by comparing the issued operation information detected by the communication quality information and said operating information detection means,
When the communication failure determination means determines that the communication quality information and the operation information have a correlation, at least the corresponding linear repeater is notified using the monitoring line that a communication failure has occurred. An optical transmission line monitoring system, comprising: a communication failure notifying means. 9. The regenerator or the multiplexing terminal equipment is C
CITT G. 707, 708, 709, wherein the communication quality information is configured to be the F1 byte or a part of the F1 byte defined by the synchronization interface. 9. The optical transmission line monitoring system according to any one of 5 to 8.