Optical cross connect apparatus

【0001】

[Technical field to which the invention belongs]

The present invention relates to an optical path switching device such as a cross-connect device for switching a large-capacity signal in an optical communication network and an ADM (Add / Drop Multiplexer) device.

【0002】

[Conventional technology]

Conventionally, in an optical communication network, line control converts an optical signal into an electric signal and performs switching control by an electric switch. However, optical / electric converters that convert optical signals into electrical signals are expensive, and in view of the ever-developing optical communication systems, a method of switching optical signals without converting them into electrical signals has been proposed, which is an obstacle. Workarounds are also being considered.

【0003】

For example, Fig. 9 shows the workaround proposed in "Patent Publication No. 10-303814". In the figure, the active optical input signal 101 and the preliminary optical input signal 102 are switched by the optical signal switching unit 106 and output to the optical output signal 107. The light levels of the current light input signal 101 and the preliminary light input signal 102 are detected by the current light level detection unit 103 and the preliminary light level detection unit 104, respectively, and the detected light level is transmitted to the light level identification unit 105. Will be done. When a failure occurs in the current optical input signal 101, the current optical level detection unit 103 detects a decrease in the light level of the current optical input signal 101, and the optical level identification unit 105 sends a switching signal to the optical signal switching unit 106. It transmits and switches to the preliminary optical input signal 102. This avoids obstacles.

【0004】

[Problems to be Solved by the Invention]

However, in an optical communication network using an optical cross-connect having multiple ports, the combination of the active path / spare path must be flexible and not fixed. The working path and the spare path do not always have a one-to-one correspondence, and it is necessary to deal with the case where a spare path called one spare vs. m working is shared by a plurality of working paths. Further, there is a problem that the number of active input (signal) lines increases, and the configuration that can deal with simultaneous defects in a plurality of active systems is considerably complicated and large-scale. In addition to this, in the event of a failure, prompt failure detection and failure recovery are required. When the path is switched, the transmission quality changes because the transmission line conditions are different, but if the fault detection threshold is set according to the worst case, it becomes difficult to judge the deterioration of the transmission quality. In addition, although it is essential to identify the faulty part immediately for quick failure recovery, there is also a problem that it takes time to identify the faulty part because the path changes floatingly. In addition, the path is set in both directions, but when switching to avoid a failure occurs, one bidirectional path shares the active system and the backup system, which complicates path management. There is also the issue of becoming.

【0005】

The present invention has been made to solve such a problem. First, a cross-connect device having a well-managed state is obtained by setting an appropriate spare path regardless of the number of input lines. .. Further, when a failure occurs, an optical cross-connect device is obtained that quickly switches the location corresponding to the reason for occurrence and finishes the switching in a short time without causing confusion to others.

【0006】

[Means for solving problems]

The optical cross-connect device according to the present invention has 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 data, and an optical signal switching unit corresponding to each detection unit. It is provided with a protection table for instructing the switching selection unit and a determination unit for switching and controlling the optical signal switching unit with reference to the protection table when a failure is detected.

【0007】

Furthermore, the determination unit monitors the path status from other nodes and changes the protection table settings according to the monitored path status.

【0008】

Furthermore, the optical signal switching unit has a configuration in which a plurality of switches for one input m (m is an arbitrary integer) output are collected, and a failure detection unit is also provided on the output side.

【0009】

Furthermore, fault detectors are provided on the input side and the output side of the optical signal switching unit.

【0010】

Furthermore, the protection table now specifies the recovery location when a failure is detected.

【0011】

Furthermore, the protection table is provided with a column for instructing switching to the related adjacent node (adjacent input side or adjacent output side) if necessary.

【0012】

Furthermore, the fault detector is provided with a threshold value for fault determination, and this threshold value is changed for each input or output.

【0013】

Furthermore, the protection table is provided with a holding time setting field, and when a failure is detected, switching control is performed after the holding time has elapsed.

【0014】

Furthermore, a backup system is prepared for both transmission and reception, and when a failure is detected, both transmission and reception as a pair are switched to the backup system.

【0015】

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. FIG. 1 is a block diagram showing Embodiment 1 according to the present invention. The optical cross-connect device according to the present embodiment is arranged before and after a plurality of optical input signals 1, a plurality of optical output signals 2, an optical signal switching unit 3 for switching optical signals, and an optical signal switching unit 3. A failure detection unit 4, a control unit 5 that controls switching between the optical signal switching unit 3, a judgment unit 6 that recognizes a failure based on the failure information from the failure detection unit 4 and gives a failure recovery instruction, and a judgment unit 6 It consists of a protection table 7 that holds failure information and recovery operation information inside, and a CPU (Central Processing Unit) 8 that exchanges control signals with other optical cross-connect devices and controls the entire optical cross-connect device. To. FIG. 2 shows the contents of the protection table 7, which is a main element of the present invention. In the figure, 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 replaced with 1a for selection. There is. This content is set by CPU8. The details of the recovery operation when each failure detection unit detects a failure are shown, and it also supports the case where multiple failure detection units detect a failure at the same time.

【0016】

Next, the operation of this configuration device will be described. The optical input signal 1 propagating in the transmission line is monitored by the fault detection unit 4 for transmission quality, 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 an optical output signal 2 via the fault detection unit 4. The failure information detected by each failure detection unit 4 is transmitted to the determination unit 6. The failure information generated from each failure detection unit 4 has a one-to-one correspondence on the protection table 7, and the recovery operation is determined on the hardware by referring to the table. When the optical path is switched as the recovery operation, the 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 (current) to 1 (spare) selection circuit may have the configuration shown in FIG. 8 (a), and conversely, the 1 input vs. m output configuration may have the configuration shown in FIG. 8 (b). Therefore, the matrix configuration of FIG. 8 (c) is possible by combining the outputs from each input of FIG. 8 (b) with the same output. In this way, many working defects can be dealt with with a small amount of reserve. That is, even in a normal system other than the so-called 1 + 1 system, a small amount of spare can be shared to improve reliability. If there is a failure detection of S1 in Fig. 2, the input port 2 which is a preliminary input is simply selected as the input. However, as shown in (Path 2) of [Table B] in Fig. 3, in this case, It is switched by requesting the upstream to switch the current input port 1 to the input port 2 side and output it.

【0018】

As described above, the optical cross-connect device according to the present embodiment immediately switches 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 the selection of signal lines is considered in advance in consideration of priority, so there is no confusion. In addition, the hardware scale can be selected on the input side only by detecting a failure on the input side, and management is easy. As described above, the optical cross-connect device according to the first embodiment can determine the recovery operation by referring to the protection table 7 in terms of hardware, so that a high-speed recovery operation can be realized.

【0019】

Another protection table in this embodiment is shown in FIG. This protection table has a table divided into [Table A] that determines the path (route) and [Table B] that determines the operation according to the detection status of the fault detector incorporated in those paths. As will be described later, there are output side detectors 40a to 40n for detecting defects in the internal circuit including the optical signal switching unit, but the optical signal switching unit 3 is configured as shown in FIG. 8 (c). Then, there is one fault detector on the input side and one on the output side in each path.

【0020】

Therefore, according to this configuration, the fault position can be determined depending on the detection status of the fault detectors 4a to 4n and the fault detectors 40a to 40n. The faulty part in [Table B] in Figure 3 shows this. When the path of this [Table B] is changed, the next process can be examined from the priority etc. at the time of the change, and therefore the recovery operation instruction is changed accordingly. This facilitates management and preparation for path changes.

【0021】

In addition to the light intensity, the fault detection unit may monitor the wavelength and the bit error rate. The path setting information between the nodes at the time of path setting includes the judgment threshold value of the failure detection unit, and the judgment threshold value is changed for each path setting. Since the optimum determination threshold value can be set according to the path setting status, it is possible to quickly detect an obstacle due to deterioration of an optical component or the like. Further, since the failure position can be transmitted at the same time as the failure detection from the failure position information set in the protection table in advance, the CPU processing at the time of failure recovery can be reduced.

【0022】

If the recovery operation requires switching to another optical cross-connect device, the CPU must send failure information to the other node. As shown in the item of recovery operation in Table B in Fig. 3, the protection table is set to send a switching instruction to another node, and when a failure occurs, the judgment unit sends the failure detection to the CPU at the same time. Since the switching instruction to the node can be transmitted, the time required for the recovery operation can be shortened. In this figure, the switching instruction is given to the upstream, but the switching instruction may be given to the downstream, and the switching may be made to the standby system in which the downstream is instructed based on this. c In an optical communication network using an optical cross-connect device, the path is not fixed and must be flexibly changed according to the client's request and the operating status of the system. Then, it will be explained that high-speed protection can be performed even when the path is changed. FIG. 4 is a diagram showing an update of the protection table in the first embodiment. When the path is set from node 1 to node 2, the protection table 1-1 showing the recovery operation when the path fails is set in node 1, and the protection table 2-1 is set in node 2. When this path is canceled, the failure detection unit detects the failure because the optical signal disappears, but since the path is canceled, the failure detected here does not require a recovery operation. By updating the protection table to the protection table 1-2 at node 1 and the protection table 2-2 at node 2 before the release, unnecessary switching operation can be suppressed.

【0023】

Also, when a new path is set from node 3 to node 2, the protection table is updated to protection table 2-3 at node 2, and a new path is set to protection table 3-1 at node 3. It is possible to perform the protection operation corresponding to. In this way, by updating the protection table at the time of path setting / cancellation, unnecessary switching can be suppressed and flexible protection operation according to the path setting status can be realized. As described above, in the optical cross-connect device according to the present embodiment, since the protection table for determining the recovery operation is updated every time the optical path is set, it is possible to flexibly respond to the change of the path. In addition, since failure detection can be performed quickly and CPU processing can be reduced, high-speed recovery operation can be realized.

【0024】

Embodiment 2. 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, 92, and a failure detection unit 4 is also arranged in an intermediate portion of an optical circuit. The failures detected by the failure detection units 4, 40, 41, and 42 are transmitted to the protection table 7 in the determination unit 6, and the recovery operation is determined on the hardware by referring to the failure information. If the failure detection unit is also provided on the output side in this way, a defect in the internal circuit between the detector on the input side can be detected. When it is determined that the failure is inside the optical cross-connect device, a switching instruction is given to the multi-stage optical signal switching unit 10 via the control unit 5 to avoid the optical signal branching / switching unit 9 in which the failure has occurred. Send.

【0025】

As described above, in the optical cross-connect device according to the present embodiment, even when the optical signal switching unit has a multi-stage configuration, by making the protection table correspond to each failure detection unit, high-speed identification of the failure position and Recovery operation can be performed.

【0026】

Embodiment 3. FIG. 6 is a diagram showing a configuration of an optical network in the present embodiment. A bidirectional path is provided with a redundant system from the start node 11 to the end node 13. The active system is composed of the active transmission path 14 and the active reception path 15, and the backup system is composed of the backup transmission path 16 and the backup reception path 17 via the 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 point node 13 detects a failure of the active transmission path 14, the end point node 13 refers to the internal protection table and switches to the preliminary transmission path 16. At the same time, the corresponding bidirectional path is read, and when viewed from the end node node 13, the transmission of the active reception path 15 that is being transmitted is stopped. The starting node 11 switches to the backup receiving path 17 in order to detect the failure of the working receiving path. As described above, since the optical cross-connect device according to the third embodiment can switch the bidirectional path at the same time, it is possible to avoid a mixture of the active system and the backup system.

【0028】

FIG. 7 is a diagram showing another network configuration in the present embodiment. A new part of the optical cross-connect device in this configuration is the provision of a retention time column, 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 spare path 28 are provided with a redundant system from the starting node 21 to the ending node 26. 22 to 25 are intermediate nodes, and the intermediate node 24 is passed through both the active path 27 and the spare path 28. Protection is set for both the intermediate node 24 and the end node node 26, and the end point node 26 is set with an appropriate holding time from the time of failure detection to the activation of the protection operation.

【0029】

When a failure occurs between the intermediate node 22 and the intermediate node 24, the failure is detected at the intermediate node 24, the intermediate node 25, and the end node node 26. The intermediate node 24 attempts to switch the active path 27 via the intermediate node 22 to the spare path 28 via the intermediate node 23. At the same time, the end node node 26 tries to switch the active path 27 via the intermediate nodes 22, 24, and 25 to the spare path 28 via the intermediate nodes 23 and 24. Since the holding time is set in the protection table, the end point node 26 does not switch immediately and waits for the holding time. In the meantime, since the intermediate node 24 switches to the spare path, the current path is restored at the end node node 26, and switching does not have to be performed. Therefore, unnecessary switching operation can be prevented and the band can be effectively utilized.

【0030】

If the retention time is included in the path setting information and set for each path setting, flexible path setting can be supported. Although the description has been given to the failure that occurred on the transmission line, the failure that occurred in the device may also be used. In this case, the end node waits for the failed device to recover by its own redundant system, and if it does not recover, it switches to the standby system. As described above, the other optical cross-connect devices in the present embodiment prioritize the failure recovery operation by appropriately providing the holding time, and do not activate a plurality of switching operations for one failure. , Appropriate recovery operation can be performed.

【0031】

[Effect of the invention]

As described above, according to the present invention, since the protection table is provided and the switching control is performed based on the protection table, there is an effect that the scale of the apparatus can be suppressed and the switching without spreading to others can be performed in a short time.

【0032】

Furthermore, since the optical signal switching unit has a configuration in which a plurality of 1-input multi-output switching units are collected, there is an effect of reducing the scale of the device.

【0033】

Furthermore, since the fault detectors are provided on the input side and the output side of the optical signal switching unit, there is an effect that the fault location can be identified.

[Simple explanation of drawings]

FIG. 1 is a diagram showing a configuration of an optical cross-connect device according to the first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a protection table according to the first embodiment.

FIG. 3 is a diagram showing another protection table according to 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 in 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 unit, 6 Judgment unit, 7 Protection table, 8 CPU, 9,91,92 Optical signal branch / switching unit, 10 Optical signal multi-stage switching unit, 11,12,13 nodes, 14,15 Active path, 16, 17 Spare path, 21 Origin node, 22,23,24,25 Intermediate node, 26 End node, 27 Active path, 28 Spare path.