JP2004040726A - Optical cross connect apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speedily switch optical signals by preventing the others from beinng disturbed while suppressing the increase of apparatus scale. <P>SOLUTION: The optical cross connect apparatus is equipped with fault detecting parts 4a, 4b...4n provided corresponding to one input, an optical signal switching part 3 for switching and selectively outputting a plurality of inputs to a plurality of outputs, a protection table 7 for instructing switching and selecting to the optical signal switching part in accordance with the detecting parts, and a judgement part 6 for controlling switching in the optical signal switching part while referring to the protection table when a fault is detected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical path switching device such as a cross-connect device or an ADM (Add / Drop Multiplexer) device for switching large-capacity signals in an optical communication network.
[0002]
[Prior art]
Conventionally, line control in an optical communication network converts an optical signal into an electric signal and performs switching control by an electric switch. However, an optical / electrical converter that converts an optical signal into an electric signal is expensive, and in view of an increasingly developed optical communication system, a method of switching an optical signal without converting it into an electric signal has been proposed. Workarounds are also being considered.
[0003]
For example, FIG. 9 shows a workaround proposed in “Japanese Patent Application Laid-Open No. 10-303814”. In the figure, an active optical input signal 101 and a standby optical input signal 102 are switched by an optical signal switching unit 106 and output as an optical output signal 107. The active optical input signal 101 and the standby optical input signal 102 have their optical levels detected by the active optical level detector 103 and the standby optical level detector 104, respectively, and the detected optical levels are transmitted to the optical level discriminator 105. Is done.
When a failure occurs in the active optical input signal 101, the active optical level detection unit 103 detects a decrease in the optical level of the active optical input signal 101, and the optical level identification unit 105 sends a switching signal to the optical signal switching unit 106. Transmit and switch to standby optical input signal 102. This avoids obstacles.
[0004]
[Problems to be solved by the invention]
However, in an optical communication network based on an optical cross-connect having multiple ports, the combination of the working path and the protection path must be not fixed but can be changed flexibly. The working path and the protection path do not necessarily correspond one-to-one, and it is necessary to cope with a case where a plurality of working paths share a protection path such as one protection-m working. Further, there is a problem that the configuration which can cope with an increase in the number of active input (signal) lines and a simultaneous failure in a plurality of active systems becomes considerably complicated and large-scale.
In addition, when a failure occurs, quick failure detection and recovery are required. When the path is switched, the transmission quality changes due to the different transmission path conditions. However, if the failure detection threshold is set according to the worst case, it becomes difficult to determine the deterioration of the transmission quality. In addition, although quick failure recovery requires quick identification of a failure location, there is also a problem that it takes time to identify the failure location because the path changes in a floating manner.
In addition, paths are set bidirectionally, but when switching to avoid a failure occurs, one bidirectional path shares the working system and the standby system, and path management becomes complicated. There is also a problem of becoming.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. First, a cross-connect device in which the size is suppressed and the state management is well performed by setting an appropriate backup path regardless of the number of input lines is obtained. .
Furthermore, an optical cross-connect device is provided in which a portion corresponding to the reason for occurrence is quickly switched when a failure occurs, and the switching without disruption to others is completed in a short time.
[0006]
[Means for Solving the Problems]
An optical cross-connect device according to the present invention, a failure detection unit provided for each input,
An optical signal switching unit that switches a plurality of inputs to a plurality of outputs and selectively outputs the signals;
A protection table for instructing the optical signal switching unit to perform switching selection corresponding to each detection unit,
A determination unit configured to switch the optical signal switching unit by referring to the protection table when a failure is detected.
[0007]
Further, the determination unit monitors the status of the path from another node, and changes the setting of the protection table in accordance with the status of the monitored path.
[0008]
Further, the optical signal switching unit has a configuration in which a plurality of switches of 1 input m (m is an arbitrary integer) output are collected, and a failure detection unit is also provided on the output side.
[0009]
Further, a failure detector is provided on the input side and the output side of the optical signal switching unit.
[0010]
Further, the protection table is designed to specify a recovery point when a failure is detected.
[0011]
Further, the protection table is provided with a column for instructing switching to a related adjacent node (adjacent input side or adjacent output side) if necessary.
[0012]
Still further, the fault detector is provided with a threshold value for fault determination, and the threshold value is changed for each input or output.
[0013]
Further, the protection table has a holding time setting column, and when a failure is detected, switching is controlled after the holding time has elapsed.
[0014]
Further, a standby system is provided for both transmission and reception, and when a failure is detected, both transmission and reception forming a pair are switched to the standby system.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing Embodiment 1 according to the present invention. The optical cross-connect device according to the present embodiment is arranged before and after the plurality of optical input signals 1, the plurality of optical output signals 2, the optical signal switching unit 3 for switching the optical signal, and the optical signal switching unit 3. A failure detection unit 4; a control unit 5 that performs switching control of the optical signal switching unit 3; a determination unit 6 that recognizes a failure based on the failure information from the failure detection unit 4 and issues a failure recovery instruction; And a protection table 7 for storing fault information and recovery operation information, and a CPU (Central Processing Unit) 8 for exchanging control signals with other optical cross-connect devices and controlling the entire optical cross-connect device. You.
FIG. 2 shows the contents of the protection table 7 which is a main element of the present invention. In the figure, the failure detection units 1 to n indicate, for example, 4a to 4n in FIG. 1, and S1 indicates that when the failure detection unit 4a detects, the optical input signal 1b is selected instead of 1a. I have. This content is set by the CPU 8. The recovery operation content when each failure detection unit detects a failure is shown, and it corresponds to a case where a plurality of failure detection units simultaneously detect a failure.
[0016]
Next, the operation of the configuration device will be described.
The optical input signal 1 that has propagated through the transmission path is monitored for transmission quality by the failure detection unit 4, and is input to the optical signal switching unit 3. The optical signal switched by the optical signal switching unit is output to the transmission line as the optical output signal 2 via the failure detection unit 4. The failure information detected by each failure detection unit 4 is transmitted to the determination unit 6. The failure information output from each failure detection unit 4 has a one-to-one correspondence on the protection table 7, and a recovery operation is determined on hardware by referring to the table. When switching the optical path as the recovery operation, a switching instruction is transmitted to the optical signal switching unit 3 via the control unit 5.
[0017]
FIG. 7 shows a detailed configuration example of the optical signal switching unit 3. The m (working) to 1 (spare) selection circuit may have the configuration shown in FIG. 8A, and the 1-input to m-output configuration may have the configuration shown in FIG. 8B. Therefore, by combining the outputs from the respective inputs in FIG. 8B with the same outputs, the matrix configuration in FIG. 8C is possible. In this manner, many current problems can be dealt with with a small number of spares. That is, even in a normal system other than the so-called 1 + 1 system, reliability can be improved by sharing a small number of spares.
When the failure is detected in S1 in FIG. 2, the input port 2 which is a spare input is simply selected as an input. In this case, as shown in (path 2) of [Table B] in FIG. The switching is performed by requesting the upstream to switch the current input port 1 to the input port 2 side for output.
[0018]
As described above, the optical cross-connect device according to the present embodiment performs switching immediately by referring to the protection table 7 directly associated with the failure detection unit switching target input set in advance by the CPU or the like. High-speed recovery is possible, and there is no confusion because selection of signal lines is considered in advance in consideration of priorities and the like. Also, the hardware scale can be selected on the input side only by detecting the failure on the input side, and management is easy.
As described above, the optical cross-connect device according to the first embodiment can determine a restoration operation by referring to the protection table 7 in hardware, and thus can realize a high-speed restoration operation.
[0019]
FIG. 3 shows another protection table according to the present embodiment. The protection table has a table divided into [Table A] for determining a path (route) and [Table B] for determining an operation corresponding to a detection state of a failure detector incorporated in the path. As will be described later, there are output side detectors 40a to 40n for detecting a failure in an internal circuit including the optical signal switching unit. However, if the optical signal switching unit 3 is configured as shown in FIG. Then, one fault detector is provided on each of the input side and the output side in each path.
[0020]
Therefore, according to this configuration, it is also possible to determine the fault position based on the detection status of the fault detectors 4a to 4n and the fault detectors 40a to 40n. The failure point in [Table B] in FIG. 3 indicates this. In this [Table B], when the path is changed, the next processing can be considered from the priority at the time of the change, and accordingly, the restoration operation instruction is changed accordingly.
Thus, management and preparation for the path change are facilitated.
[0021]
Further, the failure detection unit may monitor the wavelength and the bit error rate in addition to the light intensity. The path setting information between nodes at the time of path setting includes a judgment threshold of the failure detection unit, and changes the judgment threshold for each path setting. Since it is possible to set an optimum determination threshold value according to the path setting situation, it is possible to quickly detect a failure due to deterioration of an optical component or the like.
Further, since the fault position can be transmitted simultaneously with the fault detection from the fault position information set in the protection table in advance, the processing of the CPU at the time of fault recovery can be reduced.
[0022]
If it is necessary to switch another optical cross-connect device for the recovery operation, the CPU must transmit failure information to another node. As shown in the item of the recovery operation of the table B in FIG. 3, the content of transmitting the switching instruction to another node is set in the protection table. Since the switching instruction can be transmitted to the node, the time required for the recovery operation can be reduced. In this figure, the switching instruction is given to the upstream, but the switching instruction may be given to the downstream, and based on the instruction, the switching may be made to the standby system designated to be downstream.
(c) In an optical communication network using an optical cross-connect device, a path is not fixed, and must be flexibly changed according to a client's request or an operating state of the system. Then, it will be described that high-speed protection can be performed even when the path is changed.
FIG. 4 is a diagram illustrating updating of the protection table according to the first embodiment. When a path is set from the node 1 to the node 2, a protection table 1-1 indicating a recovery operation when a failure occurs in the path is set in the node 1, and a protection table 2-1 is set in the node 2. When the path is released, a failure is detected by the failure detection unit because there is no optical signal. However, since the path is released, the failure detected here does not require a recovery operation. Unnecessary switching operations can be suppressed by updating the protection table to the protection table 1-2 in the node 1 and the protection table 2-2 in the node 2 before release.
[0023]
When a new path is set from the node 3 to the node 2, the protection table is updated to the protection table 2-3 for the node 2, and the protection table 3-1 is set for the node 3, so that a new path is set. Can be performed.
As described above, by updating the protection table at the time of path setting / cancellation, unnecessary switching can be suppressed, and a flexible protection operation according to the path setting situation can be realized.
As described above, in the optical cross-connect device according to the present embodiment, the protection table for determining the recovery operation is updated each time an optical path is set, so that it is possible to flexibly cope with path changes. Further, since the failure detection can be performed quickly and the processing of the CPU can be reduced, a high-speed recovery operation can be realized.
[0024]
Embodiment 2 FIG.
Next, a case where the optical signal switching unit 3 has a multi-stage configuration will be described. FIG. 5 is a configuration diagram of the optical cross-connect device according to the present embodiment. A multi-stage optical signal switching unit 10 is composed of a plurality of optical signal branching / switching units 9, 91 and 92, and the fault detection unit 4 is also arranged at an intermediate portion of the optical circuit. The failure detected by each of the failure detection units 4, 40, 41, and 42 is transmitted to the protection table 7 in the determination unit 6, and a recovery operation is determined on hardware by referring to the failure information. By providing the fault detector on the output side as described above, it is possible to detect a defect in the internal circuit between the input side detector and the input side detector. If it is determined that the failure is inside the optical cross-connect device, a switching instruction to avoid the failed optical signal branching / switching unit 9 is given to the multi-stage optical signal switching unit 10 via the control unit 5. Send.
[0025]
As described above, the optical cross-connect device according to the present embodiment enables high-speed fault location and identification by associating the protection table with each fault detection unit even when the optical signal switching unit has a multi-stage configuration. A recovery operation can be performed.
[0026]
Embodiment 3 FIG.
FIG. 6 is a diagram illustrating a configuration of an optical network according to the present embodiment. A bidirectional path is provided from the originating node 11 to the ending node 13 with a redundant system. The working system includes a working transmission path 14 and a working reception path 15, and the protection system includes a protection transmission path 16 and a protection reception path 17 via an intermediate node 12. The optical cross-connect device as a node has a bidirectional path correspondence within the recovery operation of its protection table.
[0027]
Next, the operation will be described. When the end node 13 detects a failure in the working transmission path 14, the end node 13 refers to the internal protection table and switches to the backup transmission path 16. At the same time, the corresponding bidirectional path is read, and the transmission of the active reception path 15 that is being transmitted from the end point node 13 is stopped. The originating node 11 switches to the backup reception path 17 in order to detect a failure in the working reception path.
As described above, the optical cross-connect device according to the third embodiment can simultaneously switch the bidirectional paths, so that it is possible to avoid a mixture of the active system and the standby system.
[0028]
FIG. 7 is a diagram showing another network configuration according to the present embodiment. A new part of the optical cross-connect device in this configuration is that a protection time column is provided, not shown in the protection table. Then, the CPU 8 performs switching control after the holding time in this column.
A working path 27 and a backup path 28 are provided from the starting node 21 to the end node 26 with a redundant system. Reference numerals 22 to 25 denote intermediate nodes, and the intermediate node 24 has both the working path 27 and the protection path 28 passing therethrough. Protection is set for both the intermediate node 24 and the end node 26, and an appropriate holding time from when a failure is detected to when the protection operation is started is set for the end node 26.
[0029]
When a failure occurs between the intermediate nodes 22 and 24, the failure is detected at the intermediate nodes 24, 25 and the destination node 26. The intermediate node 24 attempts to switch the working path 27 passing through the intermediate node 22 to a backup path 28 passing through the intermediate node 23. At the same time, the end point node 26 attempts to switch the working path 27 passing through the intermediate nodes 22, 24, 25 to the backup path 28 passing through the intermediate nodes 23, 24. The end node 26 does not switch immediately because the retention time is set in the protection table, and waits for the retention time. In the meantime, since the intermediate node 24 switches to the backup path, the working path is restored at the end point node 26, and the switching is not performed. Therefore, unnecessary switching operation can be prevented, and the band can be used effectively.
[0030]
If the holding time is included in the path setting information and is set for each path setting, flexible path setting can be supported.
Although a description has been given of a failure that has occurred on the transmission path, a failure that has occurred in the device may be performed. In this case, the end node waits for the failed device to be restored by its own redundant system, and switches to the standby system if the failed device is not restored.
As described above, the other optical cross-connect devices according to the present embodiment, by appropriately setting the holding time, prioritize the failure recovery operation without activating a plurality of switching operations for one failure. , An appropriate recovery operation can be performed.
[0031]
【The invention's effect】
As described above, according to the present invention, a protection table is provided and switching control is performed based on the protection table. Therefore, there is an effect that switching can be performed in a short time while suppressing the size of the device and without affecting other devices.
[0032]
Furthermore, since the optical signal switching unit has a configuration in which a plurality of one-input / multiple-output switchings are collected, there is an effect of reducing the device scale.
[0033]
Further, since the fault detector is provided on the input side and the output side of the optical signal switching unit, there is an effect that a fault location can be specified.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an optical cross-connect device according to Embodiment 1 of the present invention.
FIG. 2 is a diagram illustrating an example of a protection table according to the first embodiment.
FIG. 3 is a diagram showing another protection table in the first embodiment.
FIG. 4 is a diagram illustrating a protection table update trigger according to the first embodiment.
FIG. 5 is a diagram showing a configuration of an optical cross-connect device according to a second embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of an optical network according to a third embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of another optical network according to the third embodiment.
FIG. 8 is a diagram illustrating a configuration of an optical signal switching unit according to the present invention.
FIG. 9 is a configuration diagram of a conventional optical cross-connect device.
[Explanation of symbols]
1a, 1b, 1n Optical input signal, 2a, 2b, 2n Optical output signal, 3 Optical signal switching unit, 4a, 4b, 4n, 40a, 40b, 40n, 41a, 41b, 41n, 42a, 42b, 42n Fault detector 5, control section, 6 determination section, 7 protection table, 8 CPU, 9, 91, 92 optical signal branching / switching section, 10 optical signal multi-stage switching section, 11, 12, 13 node, 14, 15 working path, 16, 17 backup path, 21 starting node, 22, 23, 24, 25 intermediate node, 26 end node, 27 working path, 28 backup path.

Claims (9)

A failure detection unit provided for each input;
An optical signal switching unit that switches a plurality of inputs to a plurality of outputs and selectively outputs the signals;
A protection table for instructing the optical signal switching unit to perform switching selection corresponding to each of the detection units;
An optical cross-connect device comprising: a determination unit configured to switch the optical signal switching unit by referring to the protection table when a failure is detected. 2. The optical cross-connect device according to claim 1, wherein the determination unit monitors a status of a path from another node, and changes a setting of a protection table according to a status of the monitored path. 2. The optical cross according to claim 1, wherein the optical signal switching unit has a configuration in which a plurality of switches of one input m (m is an arbitrary integer) output are collected and a failure detection unit is also provided on the output side. Connect device. 2. The optical cross-connect device according to claim 1, wherein the fault detector is provided on an input side and an output side of the optical signal switching unit. 2. The optical cross-connect device according to claim 1, wherein the protection table specifies a recovery point when a failure is detected. 6. The optical cross-connect device according to claim 5, wherein the protection table is provided with a column for instructing switching to a related adjacent node (adjacent input side or adjacent output side) if necessary. 2. The optical cross-connect device according to claim 1, wherein the failure detector is provided with a failure determination threshold and changes the threshold for each input or output. 2. The optical cross-connect device according to claim 1, wherein the protection table includes a holding time setting column, and when a failure is detected, switching control is performed after the holding time has elapsed. 2. The optical cross-connect device according to claim 1, wherein a standby system is prepared for both transmission and reception, and when a failure is detected, both the transmission and reception of the pair are switched to the standby system.

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