JP3090083B2 - Fault monitoring system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault monitoring system for identifying a type of a fault and specifying a location of the fault. In particular, in a passive double star system, a master station determines where the cause of the fault is. The present invention relates to a fault monitoring system to be monitored.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional passive double star system. In this passive double star system, a master station (COT) 102 to which a monitoring control device 101 is attached and a plurality of slave stations 103 _{1 to} 103 _N are provided.
It is configured to be connected by an optical transmission line for transmitting a main signal in which an optical splitter 104 is arranged in the middle. In the master station 102, an electrical / optical and optical / electrical converter (hereinafter referred to as an E / O / O / E converter) 105 for performing mutual conversion between an optical signal and an electrical signal, and detection of an uplink burst signal. An upstream burst signal detector 106 for performing the above operation is arranged. Each of the ONUs 103 _{1 to} 103 _N has an E / O / O / E for performing mutual conversion between an optical signal and an electric signal.
The conversion units 108 are arranged.

In such a system, for example, an upstream burst signal output from the E / O / O / E converter 108 of the Nth slave station 103 _N reaches the master station 102 via the optical splitter 104. Is received by the E / O / O / E conversion unit 105 and is subjected to optical-electrical conversion. The converted electric signal is supplied to a circuit portion (not shown) as a main signal 111 and is also input to an upstream burst signal detecting section 106. The upstream burst signal detection unit 106 detects a disconnection of the termination and the burst signal.
12 is sent to the monitoring control device 101.

Japanese Patent Application Laid-Open No. Hei 3-1876 discloses a technique of utilizing wavelength multiplexing for a loop type optical transmission system and detecting a faulty section by using loopback light of monitoring light.
There is a technique disclosed in JP-A-33-33. In the technique disclosed in this publication, a wavelength different from the wavelength of the main signal is assigned as a monitoring optical signal. Then, by multiplexing the monitoring optical signal with the main signal and utilizing the fact that the topology is a loop, by detecting the return light returning from the insertion point to the loop again by looping around the loop, Monitors for failures. Incidentally, Japanese Patent Application Laid-Open No. 5-29203
No. 8 also discloses a technique for multiplexing a main signal and a monitoring signal light for monitoring.

[0005]

By the way, the optical transmission system shown in FIG. 2 has a topology in which the optical splitter 104 branches into a star type. Therefore, when the proposed fault monitoring system is applied to the optical transmission system shown in FIG.
It is necessary for every 03 _{1 to} 103 _N , and there is a problem that the technology cannot be applied as it is. That is, in the conventional fault monitoring system disclosed in JP-A-3-187633, when the master station 102 does not receive a burst signal from a specific slave station 103, the type of fault is identified. However, the failure point cannot be specified on the master station 102 side. Here, the identification of the failure location means that the cause of the failure is the optical splitter 104 and the slave stations 103 _{1 to} 103.
_This means whether the N exists in the transmission path between the corresponding station and the corresponding station, or whether it exists in a portion other than the multiplexing / demultiplexing unit of the device of the slave station 103 itself.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fault monitoring system in which, when an optical signal from a specific slave station has not been received by the master station, a fault section can be separated by the master station. is there.

[0007]

According to the first aspect of the present invention, (a) a monitoring optical signal having a wavelength different from that of the main signal and assigned to a wavelength dedicated to the own station is separated from the received optical signal, and A plurality of slave stations for wavelength-multiplexing and outputting the main signal so that the monitoring optical signal dedicated to the own station is returned as it is,
(B) an optical splitter in which the plurality of slave stations are connected in a star configuration; and (c) a main signal and a monitor based on the optical signals connected to the plurality of slave stations via the optical splitter and transmitted from the slave stations. Demultiplexing means for separating optical signals for use, upstream main signal disconnection detecting means for detecting disconnection of the main signal separated by the demultiplexing means, and monitoring optical signals of a plurality of slave stations separated by the demultiplexing means Monitoring optical signal disconnection detecting means for detecting an individual disconnection of a plurality of slave stations, generating monitoring optical signals of the plurality of slave stations, multiplexing them with a main signal, and transmitting the multiplexed signals to the respective slave stations via an optical splitter. Inputting the detection results of the signal transmitting means, the main signal disconnection detecting means and the monitoring optical signal disconnection detecting means, and determining whether a failure has occurred between the optical splitter and a specific slave station by a combination of these disconnection detections From the point where the main signal and the monitoring signal are multiplexed and demultiplexed at a specific slave station Failure location is to be provided to the fault monitoring system and a master station and a monitoring determination unit which performs one of determination has occurred.

That is, according to the first aspect of the present invention, in an optical communication system in which a master station and a plurality of slave stations are connected in a star via an optical splitter, each slave station has a different main signal and wavelength. Each slave station assigns a monitoring optical signal set to a unique wavelength. Further, the plurality of slave stations return the monitoring optical signal of the own station as it is (loop back), multiplex it with the main signal, and transmit the multiplexed signal to the master station via the optical splitter. At the master station,
While transmitting the monitoring optical signal for these slave stations, the main signal disconnection detecting means for detecting the disconnection of the main signal sent from these slave stations and the monitoring light for detecting the disconnection of the monitoring optical signal of each wavelength. Signal disconnection detection means is provided, and these detection results are output to the monitoring determination means, where a failure has occurred between the optical splitter and the specific slave station or whether the specific slave station has a main signal. It is determined whether a failure has occurred at a location other than the location where the monitoring signal is multiplexed and demultiplexed. The monitoring determination means and the main signal loss detection means and the monitoring optical signal loss detection means may be physically located in the master station, or may be substantially connected to the master station in such a way as to be externally connected to the master station. It may be such that they are arranged integrally.

According to a second aspect of the present invention, in the first aspect of the present invention, the plurality of slave stations loop back a monitoring optical signal to which a wavelength dedicated to the own station, which is separated by the own station, is allocated. It is characterized in that it is multiplexed with the main signal in its own station via the optical waveguide for use and transmitted to the master station via the optical splitter. The ability to reliably return the monitoring optical signal assigned to its own station to the master station is a necessary requirement for isolating the location of the fault.

According to a third aspect of the present invention, in the first aspect of the present invention, the monitoring determining means is configured such that the monitoring optical signal disconnection detecting means does not detect only the monitoring optical signal of the specific slave station and the other slave stations. When the monitoring optical signal is detected, it is determined that a failure has occurred in the transmission path between the optical splitter and the specific slave station. This is because if a monitoring optical signal of another slave station is detected, at least a failure has not occurred in the transmission path between the master station and the optical splitter.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the main signal disconnection detecting means has not detected only the main signal of a specific slave station and the monitoring optical signal disconnection detecting means has the main signal disconnection detecting means. When a monitoring optical signal of a specific slave station is detected, it is determined that a failure has occurred in the specific slave station. Since the monitoring optical signal is simply folded back in its own device, if there is a slave station where the monitoring optical signal is detected and the main signal is not detected, it can be determined that a fault has occurred inside the slave station. Because. However, if a failure occurs at a location where the main signal and the monitoring signal are multiplexed and demultiplexed in the slave station, a situation may occur in which the monitoring optical signal is not looped back in the slave station. In such a case, there is a limit to the fault isolation.

According to a fifth aspect of the present invention, in the first aspect of the invention, the master station selectively outputs a monitoring signal light having a wavelength allocated to each of the plurality of slave stations as the monitoring signal light. Signal light selective output means, and the monitoring optical signal disconnection detection means, in synchronization with the selective output of the monitoring signal light selective output means, a monitoring signal having the same wavelength as the output wavelength. It is characterized in that it is determined whether or not the light has been returned from the corresponding slave station, thereby detecting disconnection of the monitoring signal light assigned to each slave station. By performing such time-division processing, the configuration for discrimination for each wavelength of the monitoring optical signal disconnection detecting means can be simplified.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows a fault monitoring system according to an embodiment of the present invention. In this fault monitoring system, a master station (COT) 12 to which a monitoring control device 11 is attached is provided.
And a plurality of slave units (ONUs) 13 _{1 to} 13 _N are connected by an optical transmission line for transmitting a main signal, in which an optical splitter 14 is arranged on the way.

In the master station 12, an electrical / optical and optical / electrical conversion unit (E / E) for mutually converting an optical signal and an electrical signal is provided.
It is called an / O · O / E conversion unit. ) 15, an upstream burst signal detector 16 for detecting an upstream burst signal,
A track monitoring unit 17 is provided. The burst signal detector 16 terminates the upstream burst signal, and outputs a disconnection detection signal 41 to the monitoring control device 11 for a disconnection detection character.

The line monitoring section 17 includes a multiplexing / demultiplexing section 21 for multiplexing and demultiplexing the main signal 18 and the loopback light 19.
And a loopback light 19 as an output of the multiplexer / demultiplexer 21.
And a line for supplying a wavelength selection signal 24 for selecting a wavelength to be monitored in the loopback light 19 to the disconnection detecting unit 22 and the test light source unit 25. And a monitoring control unit 26. Test the light source unit 25 accommodates the light source of the wavelength lambda ₁ to [lambda] _N corresponding one each to each child station 13 ₁ to 13 _N, to provide loop-back optical signal 19 to the demultiplexing unit 21 It has become. In addition, the disconnection detecting unit 22 performs disconnection detection based on the presence or absence of light of each wavelength from the wavelengths λ _{1 to} λ _N in accordance with the wavelength selection signal 24 provided from the line monitoring control unit 26.

On the other hand, the slave stations 13 _{1 to} 13 _N have different wavelengths of the loop-back optical signal 19 supplied for monitoring, but the other circuit configurations are the same. FIG. 1 shows only the configuration of the N-th slave station 13 _N for simplification. The N-th slave station 13 _N performs E / O · O / E for performing mutual conversion between an optical signal and an electric signal with respect to the main signal 18.
It comprises a converter 31 and a line monitoring loopback unit 32. Here, the line monitoring loopback unit 32
Includes a demultiplexing unit 33 for performing multiplexing and demultiplexing of the main signal 18 and the loop-back optical signal 19, the optical waveguide 34 of the loop-back optical signal 19 with a wavelength lambda _N.

In such a fault monitoring system, as an example, consider the line monitoring for the Nth slave station _13N . The wavelength selection signal 24 output from the line monitoring control unit 26 in the master station is input to the test light source unit 25. If this wavelength selection signal 24 is an indication of the wavelength lambda _N, the test light source unit 25 outputs the optical signal of the wavelength lambda _N. This wavelength λ
_{The N} optical signal is multiplexed with the main signal 18 in the multiplexing / demultiplexing unit 21,
The light is split by the multiplexing / demultiplexing unit 33 in the Nth slave station 13 _N via the optical splitter 14 and input to the optical waveguide 34. Then, the signal is looped back and input to the multiplexing / demultiplexing unit 33 again. In demultiplexing section 33 wavelength-multiplexed to the main signal 18 to be sent toward the optical signal of the wavelength lambda _N to the master station 12.

The master station 12 separates the loopback optical signal 19 of wavelength λ _N multiplexed on the main signal 18 in the multiplexing / demultiplexing section 21 in the line monitoring section 17 and sends it to the disconnection detecting section 22. . The disconnection detection unit 22, the instruction of wavelength selection signal 24, detects the presence or absence of a loop-back optical signal 19 of wavelength lambda _N, and notifies the result to the line monitoring control unit 26. The line monitoring controller 26 outputs the notified result as a result signal 42 to the monitoring controller 11 as necessary.

Now, the optical splitter 14 and the N-th slave station 13 _N
It is assumed that a failure has occurred in the transmission path between. As a result, the loopback optical signal 19 sent from the other slave stations 13 _{1 to} 13 _{N−1 is} sent from the Nth slave station 13 _N even though the disconnection detection unit 22 detects it. The expected loopback optical signal 19 is not detected by the disconnection detection unit 22. Thereby, it is possible to recognize that a failure has occurred in the transmission path between the optical splitter 14 and the N-th slave station _13N .

Next, in the portions other than the multiplexing / demultiplexing portion 33, the Nth slave station
13_NLet us consider a case where a device failure has occurred. In this case
Means that the burst signal detector 16 in the master station 12 is the Nth slave station
13 _NOf the upstream burst signal from the
Is notified to the monitoring control device 11. In this case, the Nth
Slave station 13_NWavelength λ corresponding to_NLoopback optical signal 1
9 can be detected by the disconnection detection unit 22 of the master station 12.
That is, in any case, the burst signal detector 16
Is the Nth child station 13_NOf burst burst signal from
However, the optical splitter 14 and the Nth_NBetween
When a failure occurs in the transmission path, the disconnection detection unit 22 outputs the wavelength λ._N
Cannot detect the loop-back optical signal 19 of
Nth child station 13_NIf the failure itself,
Is a failure other than the multiplexing / demultiplexing unit 33, the disconnection detection unit 22
λ_NCan detect the loopback optical signal 19 of FIG.
You.

Table 1 summarizes the above conclusions.
become that way.

[Table 1]

Therefore, when a fault occurs, the monitoring and control device 11 checks the signal states of both the disconnection detection signal 41 sent from the burst signal detection unit 16 and the result signal 42 sent from the line monitoring and control unit 26. Recognizing the combination, whether the cause of the failure is in the transmission path between the optical splitter 14 and the specific slave station 13 or not, the multiplexing / demultiplexing unit 33
In other words, it is possible to determine whether the failure is other than the above. Of course, the master station 12 and the optical splitter 1
It is also possible to determine whether a failure exists in the transmission path between the four.

As described above, the fault monitoring system according to the present embodiment can identify the type of fault and specify or isolate the fault location. It can be done quickly without going to the location where the slave station or optical splitter is located,
It is possible to shorten the time until the failure recovery. this is,
It is particularly useful for carriers that provide passive double star system services.

[0026]

As described above, according to the first aspect of the present invention, in an optical communication system in which a master station and a plurality of slave stations are connected in a star through an optical splitter, each of the slave stations has Since the main signal and the wavelength are different, and each slave station decides to assign a monitoring optical signal set to its own wavelength, the master station only determines the wavelength and the master station determines whether each slave station has a fault. Can be determined.

According to the fifth aspect of the present invention, the monitoring optical signal disconnection detecting means is synchronized with the selective output of the monitoring signal light selective output means and has the same wavelength as the output wavelength. By determining whether or not the monitoring signal light is returned from the corresponding slave station, the disconnection of the monitoring signal light assigned to each slave station is detected. Compared with a configuration in which the signal is incorporated and transmitted, such a time-division processing makes it possible to simplify the configuration for discriminating each wavelength of the monitoring optical signal disconnection detecting means.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a fault monitoring system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional fault monitoring system.

[Description of Signs] 11 Supervisory control device (monitoring determination means) 12 Master station 13 _{1 to} 13 _N First to Nth slave stations 14 Optical splitter 15, 31 E / O / O / E converter 16 Uplink burst signal detection Unit (main signal disconnection detecting unit) 17 line monitoring unit 21, 33 multiplexing / demultiplexing unit 22 disconnection detecting unit (monitoring optical signal disconnection detecting unit) 25 test light source unit 26 line monitoring control unit 32 line monitoring loopback unit 34 light guide Wave path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 17/02 H04B 10/08 H04B 10/20 H04B 3/46

Claims (5)

(57) [Claims] 1. A main signal which separates a monitoring optical signal having a wavelength different from that of a main signal from a received optical signal and to which a wavelength dedicated to the own station is allocated, and returns the monitoring optical signal dedicated to the own station as it is. A plurality of slave stations for wavelength multiplexing and outputting the same, an optical splitter in which the plurality of slave stations are connected in a star shape, and a plurality of slave stations connected to the plurality of slave stations via the optical splitter and transmitted from these slave stations. Branching means for separating the main signal and the monitoring optical signal from the separated optical signal, and an upstream main signal break detection means for detecting breakage of the main signal separated by the branching means,
Monitoring optical signal disconnection detecting means for detecting individual disconnection of the monitoring optical signals of the plurality of slave stations separated by the demultiplexing means; and a main signal for generating the monitoring optical signals of the plurality of slave stations and generating a main signal. And signal detection means for transmitting to the respective slave stations via the optical splitter and the detection results of the main signal disconnection detecting means and the monitoring optical signal disconnection detecting means. A failure occurs between the optical splitter and a specific slave station due to the combination of the above, or a failure occurs at a place other than the place where the main signal and the monitoring signal are multiplexed and demultiplexed at the particular slave station. A fault monitoring system, comprising: a master station having a monitoring determining means for determining whether or not a fault has occurred. 2. The plurality of slave stations, each of which separates a monitoring optical signal assigned a wavelength dedicated to the own station, separated from the own station, into a main signal within the own station via a loop-back optical waveguide of the own station. 2. The fault monitoring system according to claim 1, wherein the signal is multiplexed and transmitted to the master station via the optical splitter. 3. The monitoring determining means, when the monitoring optical signal disconnection detecting means has not detected only a monitoring optical signal of a specific slave station and has detected a monitoring optical signal of another slave station. 2. The fault monitoring system according to claim 1, wherein it is determined that a fault has occurred in a transmission path between the optical splitter and the specific slave station. 4. The monitoring discriminating means, wherein the main signal loss detecting means does not detect only a main signal of a specific slave station, and the monitoring optical signal loss detecting means detects a monitoring optical signal of the specific slave station. 2. The fault monitoring system according to claim 1, wherein when the fault occurs, it is determined that a fault has occurred in the specific slave station. 5. The master station further includes a monitoring signal light selective output unit that selectively outputs a monitoring signal light having a wavelength allocated to each of the plurality of slave stations as a monitoring signal light, The monitoring optical signal disconnection detecting means, in synchronization with the selective output of the monitoring signal light selective output means, has the monitoring signal light having the same wavelength as the output wavelength returned from the corresponding slave station? 2. The fault monitoring system according to claim 1, wherein a determination is made as to whether disconnection of the monitoring signal light allocated to each slave station is detected.