JP2002353907A - Method for detecting fault occurrence spot in optical communication network and optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely specify a spot, where a fault is occurring, in an optical connector or optical fiber cable. SOLUTION: An NMS 17 sets an optical path 15 to OXC devices 13-1 to 13-5 of an active system and sets a protection optical path 16 to OXC devices 13-1, 13-6 to 13-8 and 13-5 of a standby system. Corresponding to the notice of fault occurrence caused by optical signal reception disabled state on the optical path 15 from a router 12 for output processing, the NMS 17 makes the optical signal detour to the protection optical path 16 of the standby system. The NMS 17 successively switches the OXC devices 13-1 to 13-5 and accommodates a fault detecting signal S21 on the same optical path (logical channel) as that of the optical signal, it is discriminated by detection units 14-1 to 14-5 whether the fault detecting signal S21 has been received between respective OXC devices 13-1 to 13-5 and corresponding to the notice of reception inability, the fault occurrence spot is specified by the NMS 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission path for optical data (optical signal / transmission data, management data, etc.) by wavelength division multiplexing (WDM) transmission. Optical Cross Connect (OXC: Optical Cro)
ss Connect) The present invention relates to a method for detecting a failure location in an optical communication network and performing an error diagnosis (failure detection for identifying a failure location) in an optical communication network connected to devices, and an optical communication system.

[0002]

2. Description of the Related Art In recent years, TCP / IP (Transmission Control)
(rol Protocol / Internet Protocol) With the spread of communication (for example, Internet communication), the traffic volume in a communication network is rapidly increasing. For this reason, IP (Internet Protocol
ol) In the communication network, IETF (Internet Engineering
MPLS (Multi Pr
An efficient optical communication network using an otocol label switch (OTC), in particular, an optical communication network using an optical cross-connect device (OXC) has attracted attention. An optical communication network using this OXC performs known wavelength division multiplexing transmission, and is suitable for large-capacity data communication.

In such an optical communication network, input processing
(ingress) In order to transmit optical data (optical signal) such as transmission data and management data from a router to an output processing (egress) router, an NMS (Network Management System)
An optical path is set in advance between a plurality of working OXCs, and
A bypass optical path is set between the standby OXCs to avoid a failure. Optical processing is all performed between the OXCs.
For this reason, in the optical communication network, even if a failure occurs in an optical path between a plurality of OXCs, for example, when an optical fiber cable is disconnected, the location where the failure has occurred cannot be easily specified.

As a technique for improving the above, there is known a fault monitoring method of branching a part of optical data (optical signal), performing optical / electrical conversion, and detecting occurrence of a fault from the electrical signal (for example, Japanese Unexamined Patent Publication (Kokai) No. Heisei 9 (1994) -207). No. 10-107772).

FIG. 8 is a block diagram showing a configuration of a main part of such a conventional optical communication network. Referring to FIG.
The optical data input to C13-4 is transmitted to the optical branching unit 81-1.
And one of them is transmitted as it is as optical data. The other optical data is input to a monitor 83-1 for monitoring a fault, and the monitor 83-1 detects occurrence of a fault.
In such a configuration, optical data is branched for fault monitoring, and a loss occurs in an optical signal. For this reason, an amplifier or a repeater optical / electrical converter (O / E) and an electric / optical converter (E / O) that pass through a multi-stage OXC are arranged in the middle of an optical path to perform a reproduction process on an optical signal. There is a need. This configuration increases the scale of the apparatus and increases the cost.

A fault monitoring method using a fault detection signal having a wavelength different from the wavelength of optical data is known (for example, Japanese Utility Model Laid-Open No. 5-80048). In this fault monitoring method, there is a limitation on the wavelength used for optical data transmission. That is, since a specific wavelength is used for the failure detection signal, the specific wavelength cannot be used for transmitting optical data. For this reason, the traffic amount in the optical communication network cannot be increased. In other words, this is a factor that makes it impossible to increase the scale of the optical communication network.

[0007]

As described above, the conventional optical communication network has the following disadvantages. (1) It is difficult to specify the location where a failure has occurred because all the light processing is performed. (2) When a fault occurrence diagnosis is performed by branching optical data, a loss occurs in an optical signal. Further, in the configuration for preventing the loss of the optical signal, the configuration becomes complicated, the device scale becomes large, and the cost cannot be reduced. (3) When assigning a specific wavelength for the failure detection signal,
The transmission wavelength of optical data is limited. (4) After diagnosing the occurrence of a failure in the optical path of the working system after setting the respective optical paths of the working system and the protection system, it takes time for the occurrence of the failure, and the occurrence of the failure cannot be detected quickly. (5) A maintenance test for diagnosing the normality of the optical communication network cannot be easily performed without interrupting the communication service.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, in which a location where a failure occurs can be easily and reliably specified, transmission loss of an optical signal does not occur, and transmission of optical data is prevented. It is an object of the present invention to provide a method for detecting a location where a failure has occurred in an optical communication network and an optical communication system capable of suppressing an increase in cost and device scale without limiting the wavelength in the optical communication system and without complicating the configuration.

Further, the present invention provides an optical communication system capable of quickly detecting occurrence of a failure and easily performing a maintenance test (failure diagnosis) for determining the normality of an optical communication network without interrupting communication services. It is another object of the present invention to provide a method for detecting a failure location in a network and an optical communication system.

[0010]

In order to achieve the above-mentioned object, a method for detecting a location of a fault in an optical communication network according to the present invention comprises an optical cross-connect connected between an input side and an output side of an optical signal. Setting a light transmission path to a plurality of optical cross-connect means connected in the first optical transmission system; and detecting a failure occurrence point in the optical communication network for transmitting the optical signal by the means. Setting a detour optical transmission path to a plurality of optical cross-connect means connected in the system, detecting a failure in which an optical signal cannot be received at the output side in the optical transmission path of the first optical transmission system, Transmitting the optical signal through a detour optical transmission path of the second optical transmission system by detecting occurrence of the fault, and a fault detection signal for detecting a fault location after the detour transmission The optical signal is sequentially switched by an optical cross-connect in the optical transmission path of the first optical transmission system, accommodated in the same logical optical transmission path as the optical signal, and whether or not the failure detection signal is received between the respective optical cross-connects And a step of identifying the location of the failure.

According to the method for detecting a fault location in an optical communication network according to the present invention, a fault location in an optical communication network for transmitting an optical signal by an optical cross-connect means connected between an input side and an output side of the optical signal. And sequentially switching, by an optical cross-connect, a fault detection signal for a fault diagnosis for specifying a fault occurrence location in the optical transmission path of the first optical transmission system, so as to have the same logic as the optical signal. Accommodating in the optical transmission path, and identifying the location of the failure by the presence or absence of the failure detection signal between each of the optical cross-connect, and if the optical signal can be received at the output side in the failure diagnosis, Setting an optical transmission path to a plurality of connected optical cross-connect means of the first optical transmission system between the input side and the output side; Setting a bypass optical transmission path to a plurality of optical cross-connect means connected in the second optical transmission system when the failure is not possible; and detecting the occurrence of the failure to divert the optical signal to the second optical transmission system. Transmitting through an optical transmission path.

The method according to the present invention is characterized in that the same or different wavelength as the optical signal to be transmitted is used as the fault detection signal.

According to the method of the present invention, in order to transmit the failure detection signal at a wavelength different from that of the optical signal, optical demultiplexing is performed between the optical cross-connects and between the processing of the optical cross-connect and the detection of the failure. It is characterized by performing optical multiplexing.

The method of the present invention is characterized in that in the optical cross-connect, routing is performed by n × n optical switching for transmitting an optical signal having n input wavelengths to one of n output wavelength optical signals. I have.

[0015] In the method of the present invention, the optical cross-connect may include a wavelength division multiplex (WDM).
It is characterized in that optical clof connect by ltiplexing) transmission is executed.

An optical communication system according to the present invention comprises: a plurality of optical cross-connect means connected by a first optical transmission system in which an optical transmission path is set between an input processing means and an output processing means for an optical signal; A plurality of connected optical cross-connect means of a second optical transmission system in which a detour transmission path different from the optical transmission path of the first optical transmission system is set between the signal input processing means and the output processing means; A plurality of detection means respectively connected to the optical cross-connect means for notifying the occurrence of a failure when a failure detection signal cannot be received; (a) setting an optical transmission path in the first optical transmission system; Setting a bypass optical transmission path in the second optical transmission system, and (c) transmitting the optical signal to the second optical transmission system by a failure occurrence notification from the output processing means when the optical signal cannot be received in the optical transmission path. Detour optical transmission Road to transmit, by sequentially switching the optical cross-connect means; (d) first optical transmission system, to accommodate the failure detection signal to the same logical optical transmission path and the optical signal,
(E) a network management means for executing the above (a) to (e), which specifies a fault occurrence location based on a fault occurrence notification from the detection means.

An optical communication system according to the present invention comprises: a plurality of optical cross-connecting means connected by a first optical transmission system in which an optical transmission path is set between an input processing means and an output processing means for an optical signal; A plurality of optical cross-connecting means connected between a signal input processing means and an output processing means in a second optical transmission system in which a detour transmission path different from the optical transmission path of the first optical transmission system is set; A plurality of detection means connected to the optical cross-connect means for notifying the occurrence of a failure when a failure detection signal cannot be received; and (a) sequentially switching the optical cross-connect means of the first optical transmission system to detect a failure. House the signal in the same logical optical transmission path as the optical signal,
(B) specifying a fault occurrence location based on the fault occurrence notification from the detection means, and (c) setting an optical transmission path of the first optical transmission system when the fault diagnosis does not identify the fault occurrence location, d) setting a bypass optical transmission path of the second optical transmission system when a failure occurrence location is identified in the failure diagnosis;
(E) network management means for transmitting the optical signal through the bypass optical transmission path and performing the above (a) to (d).

The optical communication system according to the present invention is characterized in that the detecting means transmits a fault detecting signal having the same or different wavelength as the optical signal to the optical cross-connecting means, and a fault detecting signal from another detecting means. Optical receiving means for receiving through the optical cross-connect means, and a fault detecting means connected to the transmitting means and the receiving means and transmitting a fault occurrence signal to the network management means when a fault location is specified. It is characterized by having.

The optical communication system according to the present invention is characterized in that the output processing means includes a failure detecting means for detecting whether or not an optical signal is transmitted from the input processing means.

In the present invention, an optical transmission path is set in a first optical transmission system (for example, a working system), and a bypass optical transmission path is set in a second optical transmission system (for example, a standby system). ing. Then, based on the failure occurrence notification, the optical signal is transmitted through the bypass optical transmission path of the second optical transmission system, the failure detection signal is accommodated in the same logical optical transmission path (logical channel) as the optical signal, and A failure diagnosis (identification of a failure occurrence location / failure detection) in the first optical transmission system is performed based on whether or not a failure detection signal has been received. As a result, it is possible to easily and reliably specify the location where the failure has occurred.

Further, in the present invention, before setting the optical transmission path of the first optical transmission system, a failure diagnosis in the first optical transmission system is performed. As a result, it is possible to identify the location of the failure in the optical transmission path of the first optical transmission system before setting the optical transmission path and the bypass optical transmission path. That is, quick failure diagnosis can be performed.

Further, in the present invention, a fault detection signal is transmitted from an independent light source (light transmitting means) to diagnose a fault occurrence in the optical transmission path. As a result, loss of the optical signal does not occur as compared with the method of detecting a failure occurrence point where the optical signal is branched as described in the conventional example.

Further, in the present invention, the failure detection signal is accommodated in the same logical optical transmission path as the optical signal by switching by the optical cross-connect means. In other words, there is no need to assign a specific wavelength for the failure detection signal as described in the conventional example. As a result, the wavelength of the optical signal to be transmitted is not limited.

According to the present invention, the optical cross-connect means performs n.times.n optical switching for transmitting an optical signal having n input wavelengths to one of the n output wavelength optical signals. In this case, the failure detection signal can be transmitted by only one logical optical transmission path. In other words, n-1 logical optical transmission paths (logical channels) are used for transmitting optical data. As a result, the scale of the apparatus is reduced, and the cost can be reduced.

In the present invention, optical demultiplexing is performed between the optical cross-connect means, and optical multiplexing is performed between the optical cross-connect and the fault detection signal. That is, the wavelength of the failure detection signal is different from that of the optical signal.
As a result, even during the transmission of the optical signal, the failure detection signal can be transmitted to the same logical optical transmission path as the optical signal.
For example, it is possible to diagnose the normality of an optical communication network without interrupting a communication service in a maintenance test in which failure detection is performed at fixed time intervals.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for detecting a failure occurrence point in an optical communication network and an optical communication system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an optical communication network configuration according to an embodiment of the present invention. In the example of FIG. 1, an active path (first optical transmission system) optical path 15 (optical transmission path) is provided between an input processing router 11 (input processing means) and an output processing router 12 (output processing means). OXC 13-1, 13-2, 13-
3, 13-4, 13-5 (a plurality of connected optical cross-connect means of the first optical transmission system) are connected. Also,
A protection optical path 1 of a standby system (second optical transmission system) is provided between the input processing router 11 and the output processing router 12.
OXC 13-1, 1 in which 6 (detour optical transmission path) is set
3-6, 13-7, 13-8 and 13-5 (a plurality of connected optical cross-connect means of the second optical transmission system) are connected.

In this example, OXC13-1 to OXC13-13
NMS (Network Management System) 17 (network management means) for managing the optical communication network (here, failure detection / diagnosis for identifying a failure occurrence location) is provided. . In addition, OXC13-1
13-8, between each of the NMS 17 and the NMS 17, a detection unit 1 for detecting a fault occurrence location by fault diagnosis.
4-1, 14-2, 14-3, 14-4, 14-5, 1
4-6, 14-7 and 14-8 (detection means) are connected.

Next, the operation of the embodiment will be described. First Embodiment FIG. 2 is a block diagram for explaining fault occurrence diagnosis according to the first embodiment, and FIG. 3 is a flowchart showing a processing procedure of a main part operation in the first embodiment. 2 and 3
First, an optical path 15 for transmitting optical data (optical signal) from the input processing router 11 to the output processing router 12 in accordance with an instruction of the NMS 17 is connected to the OXCs 13-1 to 13-5.
Set between. Further, according to an instruction from the NMS 17, the protection optical path 16 for detouring when a failure occurs in the optical path 15 is set to the OXC 13-1, 13-6 to OXC 13-1.
It is set between 3-8 and 13-5 (step S501).

The OXCs 13-1 to 13-8 have a wavelength (λ).
Cross connect (optical switching) is performed in units. Specifically, in wavelength division multiplexing (WDM) transmission, optical data of an arbitrary optical path (highway) and an arbitrary wavelength is converted into an arbitrary optical path and an arbitrary wavelength.

When the optical path 15 is set, optical data communication from the input processing router 11 to the output processing router 12 becomes possible, and particularly, a failure occurs between the input processing router 11 and the output processing router 12. If not, normal optical data transmission is performed (step S502). When a failure occurs in the optical path 15, the output processing router 1
In step 2, optical data cannot be received (step S50).
3). The output processing router 12 recognizes the occurrence of the failure by detecting the loss of the optical data (reception disabled state) and sends a failure detection signal (alarm signal) to the NMS 17 (steps S504 and S505).

The NMS 17 starts a fault detecting operation for specifying a fault location (step S506). NMS17
OXC 13-1, 13-13 in the standby system so that the transmission path is switched to the protection optical path 16 preset between the input processing router 11 and the output processing router 12.
6 to 13-8 and 13-5 are instructed to secure transmission of optical data (step S507). In addition, NMS 17
The start of the failure detection operation is determined by the input processing router 11 and the output processing router 12, OXC 13-1 to OXC 13-5.
Then, it notifies the detection units 14-1 to 14-8 (step S508). OXC13-1 to 13-5 are NMS
Upon receiving the notification of the start of the failure detection operation from No. 17, the transmission path is switched so that the failure detection signal S21 is transmitted on the same optical path (logical optical transmission path / logical channel) as the optical data (step S509). .

The detection unit 14-5, which has received the failure occurrence notification from the NMS 17, first sets the OXC 13-5 to OXC 13-5.
The diagnosis of the normality in the optical path 15 between -4 and -4 (failure detection for identifying the location of the failure) is performed. The failure detection signal S21 is transmitted on the same optical path (logical channel) as the optical data by the optical cross-connect in the OXC 13-5 (step S510).

Here, OXC13-5 and OXC13-
Since no failure has occurred in the optical path 15 between the OXC 13 and the OXC 13-, the failure detection signal S21 is output from the detection unit 14-5.
5 is sent. The failure detection signal S21 is output from the OXC13-
After passing through the optical path 15 between 5 and 13-4, the OXC 13-4
Through the detection unit 14-4. The detection unit 14-4 detects that the optical path 15 between the OXCs 13-5 to 13-4 is normal (step S51).
1). The failure detection signal S21 is output from the detection unit 14-.
4, the failure occurrence in the optical path 15 between the OXCs 13-5 to 13-4 is identified (Step S).
512).

Upon receiving the normal signal, the detection unit 14-4 sends the OXC 13-
It notifies that the optical path 15 between 5 and 13-4 is normal, and transmits a failure detection signal S21 to diagnose the next optical path 15 between OXC 13-4 and OXC 13-3 (step). S513). This failure detection signal S21
Cannot be passed through the optical path 15 between the OXC 13-4 and the OXC 13-3 due to the occurrence of a failure, and is not input to the detection unit 14-3 through the OXC 13-3. NMS1
7, the detection unit 14-3, which is scheduled to input the failure detection signal S21, switches the OXC1
It is determined that a failure has occurred in the optical path 15 between the 3-4 and the OXC 13-3, and the location where the failure has occurred is specified (steps S514 and S515).

Next, the operation of specifying the location where a failure has occurred will be described with reference to FIG. FIG. 4 is a block diagram for explaining an operation for identifying a failure occurrence point in the first embodiment. FIG.
In the example, the output processing router 12 is provided with a line card 31 for receiving optical data and a fault detection circuit 32.
In addition, the detection units 14-4 and 14-5 (the other detection units 14-1 to 14-3 and 14-6 to 14-8 have the same configuration), together with the optical transmission circuits 35-4 and 35-5, Failure detection circuits 34-4 and 34-5, and optical reception circuit 33-
4,33-5 are provided.

In FIG. 4, the line card 31 of the output processing router 12 receives the optical data transmitted from the input processing router 11. The line card 31 is OXC13-1
When a failure occurs in the optical path 15 to 13-5 and optical data cannot be received from the input processing router 11, a failure occurrence signal indicating the occurrence of a failure is detected by detecting the loss of the optical data and sent to the failure detection circuit 32. Send out. Upon receiving the failure occurrence signal, the failure detection circuit 32 notifies the NMS 17 of the occurrence of the failure in the optical path 15.

Upon receiving the failure notification, the NMS 17 instructs the protection optical path 16 preset between the input processing router 11 and the output processing router 12 to switch the optical data transmission path. And the start of the failure detection operation is determined by the input processing router 11, the output processing router 12, and the OXC 13.
-1 to 13-8 and detection units 14-1 to 14-8
Notify. The OXCs 13-1 to 13-5 respond to the instruction signal from the NMS 17 to input the failure detection signal S21.
Is switched so that the data is transmitted on the same optical path (logical channel) as the optical data.

The switching of the optical transmission path in the OXCs 13-1 to 13-8 will be described. FIG. 5 shows OXC1
It is a figure for explaining the routing by optical switching in 3-1 to 13-8. In FIG. 5, OXC
13-1 to 13-8 are configurations of optical switches n × n (n is an integer and FIG. 4 is a case where n = 4). Optical switch n × n
OXCs 13-1 to 13-8 switch (route) n input wavelengths (optical data) to one of n output wavelengths (optical data). n corresponds to the number of wavelength division multiplexing.

The optical switch outputs optical data from IN1 to OUT.
1, IN2 to OUT2 and IN3 to OUT3. When the optical data transmission from IN1 to OUT1 is interrupted due to the occurrence of a failure, the OXC (any of 13-1 to 13-8) outputs a failure detection signal that has passed through the same optical path as the optical data based on the instruction signal of the NMS 17. S21 is O
Extraction at UT1 to IN4 and detection unit (14
-1 to 14-8).

Then, based on the instruction signal from the NMS 17, the OXC (any of 13-1 to 13-8) outputs the fault detection signal S21 output from the detection unit (any of 14-1 to 14-8). Is input from OUT4 to IN1 and switched to pass through the same optical path as the optical data. Thereby, the detection units (14-1 to 14-8)
Is transmitted on the same optical path (logical channel) as the optical data, and the failure diagnosis can be performed.

In FIG. 4, the failure detection circuit 34-5 in the detection unit 14-5 which has received the start of the failure detection operation from the NMS 17 performs diagnosis for the optical path 15 between the OXCs 13-5 to 13-4. , And instructs the optical transmission circuit 35-5 to output the failure detection signal S21. Optical transmission circuit 3
The OXC is transmitted by the failure detection signal S21 transmitted by the OXC 5-5.
13-5 is switched, and the failure detection signal S21 is transmitted on the same optical path (logical channel) as the optical data through the same optical path as the optical data and is input to the OXC 13-4.

The failure detection signal S21 is transmitted to the detection unit 14
-4 is input to the optical receiving circuit 33-4. Upon receiving the failure detection signal S21, the optical receiving circuit 33-4 notifies the failure detection circuit 34-4. Upon receiving this notification, the failure detection circuit 34-4 determines that the optical path 15 between the OXCs 13-5 to 13-4 is normal, and the next OXC 13-4 and O
In order to diagnose the optical path between the XCs 13 and 3, an instruction is sent to the optical transmission circuit 35-4 to transmit the failure detection signal S21. Then, as described above with reference to FIGS. 1 to 3, the failure detection signal S21 is transmitted to the next OXC 13-4 and the next OXC 13-4.
Since the optical path 15 between the XCs 13 and 3 cannot pass through due to a failure, the failure detection operation from the NMS 17
The detection unit 14-3, which is to input the failure detection signal S21, detects that a failure has occurred in the optical path 15 between the OXC 13-4 and the OXC 13-3. In this manner, the optical path 15 is sequentially output from the output processing router 12 side.
Is diagnosed, and the NMS 17 specifies a failure occurrence location.

As described above, in the first embodiment, the failure detection signal 21 is switched by the OXCs 13-1 to 13-8 and accommodated in the same optical path (logical channel) as the optical data.
In this case, the normality in the optical path 15 between the plurality of OXCs 13-1 to 13-8 is sequentially determined by the detection units 14-1 to 14-8 connected to the plurality of OXCs 13-1 to 13-8, respectively. Diagnosed. As a result, it is possible to easily and reliably specify the location where the failure has occurred.

In the first embodiment, the failure detection signal S21 is transmitted from independent light sources (the optical transmission circuits 35-4 and 35-5 in FIG. 4) provided in the detection units 14-1 to 14-8. Then, the occurrence of a failure in the optical path 15 between the OXCs 13-1 to 13-8 is diagnosed.
Therefore, loss of an optical signal (optical data) does not occur as compared with the operation of detecting a failure occurrence point where optical data is branched as described in the conventional example. As a result, the level fluctuation of the optical signal (optical data) disappears, and the first embodiment can be easily applied to the optical communication network.

Further, in the first embodiment, the failure detection signal S21 is accommodated in the same optical path (logical channel) as the optical data by switching the OXCs 13-1 to 13-8. In other words, there is no need to assign a specific wavelength for the failure detection signal S21. As a result, it is not necessary to limit the wavelength of the optical data. Also in this case, the first embodiment can be easily applied to an optical communication network.
In the first embodiment, the OXC of the optical switch n × n
In this case, for example, a failure detection signal can be transmitted by only one optical path (logical channel). In other words, n-1 optical paths can be used for transmitting optical data. As a result, the configuration of the detection units 14-1 to 14-8 is simplified, and the cost and size can be reduced.

Second Embodiment FIG. 6 is a block diagram showing the configuration of an optical communication network according to a second embodiment. In the above-described first embodiment, after the optical path 15 and the protection optical path 16 are set, the failure diagnosis on the optical path 15 is performed. However, in the second embodiment,
Before setting the optical path 15 between the input processing router 11 and the output processing router 12, a fault diagnosis for the optical path 15 is performed. In the second embodiment shown in FIG. 6, the optical path 15 between the input processing router 11 and the output processing router 12 is sequentially diagnosed by the optical path setting signal S61.

The operation of the fault diagnosis is the same as that of the first embodiment, and the position on the optical path 15 where the optical path setting signal 61 cannot be received by the detection units 14-1 to 14-5 is the fault occurrence location. As a result, before setting the optical path 15, it is possible to perform a fault diagnosis for quickly identifying a fault location. Then, as shown in FIG. 6, a failure occurs between the OXC 13-3 and the OXC 13-4, and the optical path 15
Is not set, the OXCs 13-1, 13-6 to 13 between the input processing router 11 and the output processing router 12 can be set.
The protection optical path 16 is set between −8 and 13-5. As a result, the normality of the optical path 15 can be diagnosed without interrupting the communication service, for example, in a maintenance test in which failure detection is performed at regular time intervals.

As described above, in the second embodiment, before the optical path 15 is set, the location where the failure has occurred in the optical path 15 is detected. As a result, it is possible to quickly identify the location where the failure has occurred.

[0049] Third Embodiment FIG. 7 is a block diagram showing an optical communication network configuration according to a third embodiment.
is there. Referring to FIG. 7, the OXCs 13-1 to 13-5
The optical demultiplexers 71-1, 71-2, 71-3,
71-4 are provided. OXC13-2 to OXC13-1
Between 3-5 and detection units 14-2 to 14-5
Optical multiplexers 72-1, 72-2, 72-3, 72-4
Is provided. Optical splitters 71-1 to 71-4 and optical coupler
The wave filters 72-1 to 72-4 are provided with wavelength division multiplexing (optical frequency
Heavy / WDM) filter. Optical demultiplexers 71-1 to 71
-4 indicates a plurality of optical signals (optical data) by wavelength multiplexing.
Multiple physical transmission lines divided into optical data of different wavelengths
(Optical fiber cable). Also, the optical multiplexer 7
2-1 to 72-4 store a plurality of optical data of different wavelengths in one.
Housed in two physical transmission lines (optical fiber cables)
To send. Note that the standby OXC 13-1, 1
3-6 to 13-8, OXC13-5 also have optical demultiplexers and optical
A multiplexer can be provided in the same manner as described above.

In the third embodiment, a failure detection signal S21a having a wavelength different from that of the optical data is used as the failure detection signal. As a result, even during transmission of optical data, the failure detection signal S21 can be transmitted on the same optical path (logical channel) as the optical data. As a result, for example,
In a failure occurrence diagnosis such as a maintenance test in which failure detection is performed at regular time intervals, the normality of the optical path 15 can be diagnosed without interrupting the communication service.

In the first to third embodiments, the optical communication network having the working system and the protection system has been described. However, a similar failure occurs in an optical communication network having only the working system and the protection system. A diagnostic operation can be performed. In the first to third embodiments, the same failure occurrence diagnosis operation as that of the active system is performed in the standby system (active system after switching) that is switched when a failure occurs in the active system. is there. The present invention also includes a fault diagnosis in the optical communication network having no protection system and a fault diagnosis in the active system after switching.

[0052]

As is apparent from the above description, according to the method for detecting a failure point in an optical communication network and the optical communication system of the present invention, the optical transmission path of the first optical transmission system (for example, the working system). Is set, the failure detection signal is accommodated in the same logical optical transmission path as the optical signal, and the failure diagnosis in the first optical transmission system is performed based on whether or not the failure detection signal has been received. As a result, it is possible to easily and reliably specify the location where the failure has occurred.

Further, according to the present invention, before setting the optical transmission path of the first optical transmission system, the failure diagnosis in the first optical transmission system is performed. As a result, it is possible to specify the location of the failure in the optical transmission path of the first optical transmission system before setting the optical transmission path and the detour optical transmission path, so that it is possible to quickly diagnose the failure.

According to the present invention, a fault detection signal is transmitted from an independent light source. As a result, there is an effect that the loss of the optical signal does not occur as compared with the detection method of the failure occurrence point where the optical signal is branched.

Further, according to the present invention, the fault detection signal is accommodated in the same logical optical transmission path as the optical signal, and it is not necessary to allocate a specific wavelength for the fault detection signal. As a result, there is an effect that the wavelength of the optical signal to be transmitted is not limited.

According to the present invention, an optical signal having n input wavelengths is routed to any one of n output wavelength optical signals by n × n optical switching, and a fault is detected by only one logical optical transmission path. Signals can be transmitted. As a result, there is an effect that the scale of the apparatus is reduced and the cost can be reduced.

According to the present invention, the optical demultiplexing is performed between the optical cross-connect means, and the optical multiplexing is performed between the optical cross-connect and the fault detection signal, so that the wavelength of the fault detection signal is defined as the optical signal. Have different wavelengths. As a result,
Even during transmission of an optical signal, there is an effect that a failure detection signal can be transmitted to the same logical optical transmission path as the optical signal.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an optical communication network configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a failure occurrence diagnosis according to the first embodiment.

FIG. 3 is a flowchart showing a processing procedure of a main part operation in the first embodiment.

FIG. 4 is a block diagram for explaining a failure location specifying operation in the first embodiment.

FIG. 5 is a diagram for explaining routing by switching of the optical cross-connect device in the first embodiment.

FIG. 6 is a block diagram illustrating an optical communication network configuration according to a second embodiment.

FIG. 7 is a block diagram illustrating an optical communication network configuration according to a third embodiment.

FIG. 8 is a block diagram showing a main configuration of a conventional optical communication network.

[Explanation of symbols]

 Reference Signs List 11 router for input processing 12 router for output processing 13-1 to 13-8 OXC 14-1 to 14-8 detection unit 15 optical path 16 protection optical path 17 NMS 31 line card 32 failure detection circuit 33-4, 33-5 Optical receiving circuit 34-4, 34-5 Failure detecting circuit 35-4, 35-5 Optical transmitting circuit 71-1 to 71-4 Optical demultiplexer 72-1 to 72-4 Optical multiplexer S21, S21a Failure detection signal S61 Optical path setting signal

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 3/26 H04B 9/00 E H04Q 3/52 H04Q 11/04 L 11/04 F-term (Reference) 5K002 DA02 DA09 EA07 EA33 FA01 5K019 AA02 BA03 CD12 EA26 5K042 CA07 CA10 DA33 EA05 FA01 HA13 JA08 LA11 5K069 AA10 BA09 CB10 DB33 FA23 HA08

Claims (10)

[Claims] 1. A method for detecting a fault occurrence point in an optical communication network for transmitting an optical signal by an optical cross-connect means connected between an input side and an output side of the optical signal, wherein the first and second optical transmission systems are connected to each other. Setting an optical transmission path to the plurality of optical cross-connect means; setting a bypass optical transmission path to the plurality of optical cross-connect means connected in the second optical transmission system; Detecting the occurrence of a failure in which the optical signal cannot be received at the output side in the path; transmitting the optical signal through the bypass optical transmission path of the second optical transmission system by detecting the failure; The failure detection signal for detecting the occurrence location is sequentially switched by an optical cross-connect in the optical transmission path of the first optical transmission system, and the same logic as that of the optical signal is used. Identifying the location of the failure based on whether or not the failure detection signal has been received between the optical cross-connects, respectively, between optical cross-connects. Detection method. 2. A method for detecting a failure point in an optical communication network in which an optical signal is transmitted by an optical cross-connect means connected between an input side and an output side of an optical signal, wherein: A failure detection signal for failure diagnosis that specifies a failure occurrence point in the transmission path is sequentially switched by an optical cross connect, accommodated in the same logical optical transmission path as the optical signal, and between each of the optical cross connects. Specifying the location of the failure based on whether or not the failure detection signal has been received; and, if an optical signal can be received at the output side in the failure diagnosis, the first optical transmission system is connected between the input side and the output side. Setting an optical transmission path to the plurality of optical cross-connect means; and connecting the optical signal in the second optical transmission system when an optical signal cannot be received on the output side in the fault diagnosis. Setting a detour optical transmission path to the plurality of optical cross-connect means, and transmitting the optical signal through the detour optical transmission path of the second optical transmission system by detecting the occurrence of the failure. The method for detecting a fault occurrence location in an optical communication network according to claim 1. 3. The method according to claim 1, wherein the fault detection signal uses the same or different wavelength as an optical signal to be transmitted. 4. In order to transmit the fault detection signal at a wavelength different from that of an optical signal, optical demultiplexing is performed between optical cross-connects and optical multiplexing is performed between processing for optical cross-connect and fault detection. 4. The method according to claim 3, wherein a failure occurrence point is detected in the optical communication network. 5. The optical cross-connect, wherein n × n optical switching routing for transmitting n-system input wavelength optical signals to any of n-system output wavelength optical signals is performed. 3. The method for detecting a fault occurrence location in the optical communication network according to 1 or 2. 6. The optical cross-connect according to claim 1, wherein said optical cross-connect comprises wavelength division multiplexing (WDM).
3. The method according to claim 1, wherein an optical link connection is performed by transmission. 7. A plurality of optical cross-connecting means connected by a first optical transmission system in which an optical transmission path is set between an input processing means and an output processing means for an optical signal; A plurality of optical cross-connecting means connected to the output processing means in a second optical transmission system in which a detour transmission path different from the optical transmission path of the first optical transmission system is set; A plurality of detecting means connected to each other and notifying occurrence of a failure when a failure detection signal cannot be received; (a) setting an optical transmission path in the first optical transmission system; and (b) setting a light transmission path in the second optical transmission system. Setting a detour optical transmission path, and (c) transmitting the optical signal through the detour optical transmission path of the second optical transmission system according to a failure occurrence notification from the output processing means when an optical signal cannot be received in the optical transmission path. , (D) said The optical cross-connect means of one optical transmission system are sequentially switched to accommodate the failure detection signal in the same logical optical transmission path as the optical signal, and (e) specifying the failure location by the failure notification from the detection means. An optical communication system, comprising: network management means for executing the above (a) to (e). 8. A plurality of optical cross-connecting means connected by a first optical transmission system in which an optical transmission path is set between an input processing means and an output processing means for an optical signal; A plurality of optical cross-connecting means connected to the output processing means in a second optical transmission system in which a detour transmission path different from the optical transmission path of the first optical transmission system is set; A plurality of detection means connected to each other and notifying the occurrence of a failure when a failure detection signal cannot be received; and (a) sequentially switching the optical cross-connect means of the first optical transmission system so that the failure detection signal is the same as the optical signal. (B) specifying a fault occurrence location by the fault occurrence notification from the detection means,
(C) setting the optical transmission path of the first optical transmission system when the failure occurrence location is not identified by the failure diagnosis; and (d) setting the second optical transmission when the failure occurrence location is identified by the failure diagnosis. A network management means for setting a detour optical transmission path of the system and transmitting an optical signal through the detour optical transmission path, and executing the above (a) to (d). Communications system. 9. An optical transmission means for transmitting a failure detection signal having the same or different wavelength as an optical signal to an optical cross-connect means, and a failure detection signal from another detection means to an optical cross-connect means. Optical receiving means for receiving through, and a fault detecting means connected to the transmitting means and the receiving means and transmitting a fault occurrence signal to the network management means when a fault occurrence location is specified, characterized by comprising: The method according to claim 7 or 8, wherein a failure occurrence location in the optical communication network is detected. 10. The fault occurrence location in the optical communication network according to claim 7, wherein the output processing means includes fault detection means for detecting whether or not an optical signal is transmitted from the input processing means. Detection method.