Optical communication system and optical communication method

Abstract

To solve a problem in which it is difficult in an optical network to recover from multiple failures without decreasing utilization efficiency of the optical network.SOLUTION: An optical communication system includes: an optical network management apparatus comprising an optical path setting means for setting a plurality of active paths to a first physical route and setting a plurality of backup paths corresponding to the active paths, respectively, to a plurality of physical routes different from the first physical route, and a failure-case optical path setting means for at least setting, when a fault occurs in multiple paths including the active path, out of the active paths and the backup paths, a failure-case optical path with a modified band of the backup path, to at least one of multiple physical routes different from a physical route where faulty paths are set; and an optical node device including optical transceiver means for transmitting and receiving optical signals using optical path settings configured by the failure-case optical path setting means.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical communication system and an optical communication method, and particularly to an optical communication system and an optical communication method used in a backbone optical network.

Background Art

[0002] A backbone optical network provides a function of communicating traffic of client devices via an optical fiber communication path connecting sites according to a contracted service quality (service class). Here, the backbone optical network receives a client signal via an interface between a node device and a client device. Then, after multiplexing a plurality of client signals using various multiplexing methods, communication is performed via a backbone transmission communication path with a larger capacity. As the multiplexing method, a wavelength division multiplexing (WDM) method, a time division multiplexing (TDM) method, an orthogonal frequency division multiplexing (OFDM) method, etc. are used.

[0003] In the backbone optical network, communication of ultra-large-capacity traffic of 100 Gbps (Giga bit per second) class per channel is performed. Therefore, in the backbone optical network, a failure recovery technology for failures caused by disconnection of an optical fiber, failure of an optical node device, etc., and a technology for improving the utilization efficiency of optical frequency resources are important.

[0004] As a failure recovery technology, a 1+1 protection method, a shared protection method, etc. are known, and an example of such a failure recovery technology is described in Patent Document 1.

[0005] The signal switching device described in Patent Document 1 includes a signal switching unit, a branching unit that branches the user signal for redundancy, and a device monitoring and control unit that monitors and controls the entire device. The signal switching device transmits the user signal to the other signal switching device via the active path, the first standby path, and the second standby path. The other signal switching device receives the received signal from the above paths, monitors the signal states of the active path and the standby paths in the signal monitoring unit, and then selects a normal signal by the selection unit and outputs it to the user device.

[0006] When the active path is normal, the signal switching unit is set to connect to the active path. When a failure occurs in the active path, the selection unit of the receiving-side switching device selects the signal from the first standby path and outputs it to the user device.

[0007] The signal monitoring unit of the standby path monitors the first standby path. When a failure such as signal loss or error rate threshold exceeding is detected in the signal from the first standby path, the device monitoring and control unit controls the signal switching unit to switch the connection from the first standby path to the second standby path.

[0008] With such a configuration, the standby system can always be maintained normally, so a highly reliable 1+1 redundancy configuration that can also handle double failures of the transmission path and devices between the transmission and reception nodes can be realized.

[0009] On the other hand, in order to effectively utilize optical frequency resources, the elastic optical network method has been proposed (see, for example, Patent Document 2). In the elastic optical network method, on a network where a plurality of nodes are connected by optical fibers, it is possible to allocate the minimum necessary frequency band according to the transmission capacity of the optical signal to the path between the nodes that transmit and receive the optical signal. Also, in the elastic optical network method, the allocated frequency band can be flexibly determined by the number of slots with a predetermined frequency width as one slot unit.

[0010] Thus, according to the elastic optical network method, the required number of wavelength slots for an optical path can be varied according to the required capacity of traffic. As a result, it becomes possible to allocate optical paths to surplus wavelength resources that could not be utilized in the conventional fixed grid network, and improve the utilization efficiency of the optical network.

[0011] In addition, as related technologies, there are the technologies described in Patent Documents 3 to 5.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0013] In the above-described failure recovery technology, a configuration is adopted in which a first backup path and a second backup path are provided for an active path. That is, a plurality of backup paths are set in advance in case of failures occurring simultaneously at a plurality of locations, and the influence of a failure is avoided by switching to a remaining backup path when a failure occurs.

[0014] In this case, in order to accommodate one traffic request, wavelength resources for preparing three or more optical paths are required. Therefore, there is a problem that the utilization efficiency of the optical network is significantly reduced.

[0015] Thus, in an optical network, there has been a problem that it is difficult to recover from a multiple failure without causing a decrease in the utilization efficiency of the optical network.

[0016] An object of the present invention is to provide an optical communication system that solves the above-described problem, that is, in an optical network, it is difficult to recover from a multiple failure without causing a decrease in the utilization efficiency of the optical network.

Means for Solving the Problem

[0017] The optical communication system of the present invention includes an optical path setting means for setting a plurality of working paths on a first physical path and setting a plurality of protection paths corresponding to each of the plurality of working paths on a plurality of physical paths different from the first physical path, respectively, and a failure-time optical path setting means for setting at least a failure-time optical path in which the bandwidth of the protection path is changed on at least one of the plurality of physical paths different from the physical path on which the plurality of paths including the working path have failed when a failure occurs in the plurality of paths including the working path among the working paths and the protection paths. The optical network management device includes an optical transmission / reception means for transmitting and receiving an optical signal based on the optical path setting set by the failure-time optical path setting means. The optical communication method of the present invention includes setting a plurality of working paths on a first physical path, setting a plurality of protection paths corresponding to each of the plurality of working paths on a plurality of physical paths different from the first physical path, respectively, setting at least a failure-time optical path in which the bandwidth of the protection path is changed on at least one of the plurality of physical paths different from the physical path on which the plurality of paths including the working path have failed when a failure occurs in the plurality of paths including the working path among the working paths and the protection paths, and transmitting and receiving an optical signal based on the optical path setting set at the time of the failure.

Effect of the Invention

[0018] According to the optical communication system of the present invention, it is possible to recover from a multiple failure without causing a decrease in the utilization efficiency of the optical network.

Brief Description of the Drawings

[0019]

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Best Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the directions of the arrows in the drawings are for illustrative purposes only and do not limit the directions of signals between blocks.

[0021] 〔First Embodiment〕 FIG. 1 is a block diagram showing the configuration of an optical communication system 1000 according to the first embodiment of the present invention. The optical communication system 1000 includes an optical network management device 100 and an optical node device 200.

[0022] The optical network management device 100 includes an optical path setting means 110 and a backup optical path setting means 120 in case of failure. The optical path setting means 110 sets a backup path for each of a plurality of operating paths on the same physical path to different physical paths. The backup optical path setting means 120 in case of failure sets a backup path in case of failure with the bandwidth of the backup path compressed to a physical path where no failure has occurred when a failure has occurred in two or more physical paths among the physical paths.

[0023] The optical node device 200 includes an optical transmission / reception means 210 that transmits and receives optical signals using the backup path information in case of failure, which is the result set by the backup optical path setting means 120 in case of failure.

[0024] Next, the optical path setting method according to the present embodiment will be described. In the optical path setting method according to the present embodiment, first, a backup path for each of a plurality of operating paths on the same physical path is set to different physical paths. Then, a backup path in case of failure with the bandwidth of the backup path compressed is set to a physical path where no failure has occurred when a failure has occurred in two or more physical paths among the physical paths.

[0025] Thus, in the optical communication system 1000 and the optical path setting method according to this embodiment, a plurality of physical paths are set in advance as candidates for the physical paths of the standby paths, and each standby path is distributed. Then, when a failure occurs simultaneously in a plurality of physical paths, the optical band of the standby path is compressed to accommodate the optical path affected by the failure. Thereby, it is possible to recover from a multiple failure without causing a decrease in the utilization efficiency of the optical network.

[0026] Here, the optical path setting means 110 can be configured to set a plurality of standby paths for each of the plurality of operation paths in physical paths with substantially the same communication quality. Further, the optical path setting means 120 at the time of failure can be configured to compress the band of the standby path based on the band guarantee rate at the time of a multiple failure.

[0027] 〔Second Embodiment〕 Next, a second embodiment of the present invention will be described. FIG. 2 shows a schematic configuration of an optical communication system 2000 according to this embodiment. As shown in the figure, the optical communication system 2000 includes an optical network management device 300 and optical node devices 401 to 406, and each optical node device is connected by an optical fiber communication path.

[0028] FIG. 3 shows the configurations of the optical network management device 300 and the optical node device 401 that constitute the optical communication system 2000 according to this embodiment.

[0029] The optical network management device 300 has a database unit 310, an optical path design unit 320, and an optical path allocation control unit 330.

[0030] The database unit 310 includes a request traffic DB (database) 311, a network facility DB 312, an optical path management DB 313, and a multi-failure time-bandwidth guarantee rate DB 314. The optical path design unit 320 includes a route search unit 321, a wavelength slot / fiber allocation determination unit 322, and a multi-failure time wavelength slot number determination unit 323. Here, the route search unit 321 and the wavelength slot / fiber allocation determination unit 322 constitute an optical path setting means, and the multi-failure time wavelength slot number determination unit 323 constitutes an optical path setting means during a failure.

[0031] On the other hand, the optical node device 401 includes a failure detection unit 410, a bandwidth variable optical transponder 420, a standby path switching control unit 430, and a large-granularity variable switching device 440. Here, the bandwidth variable optical transponder 420 and the large-granularity variable switching device 440 constitute an optical transmission / reception means.

[0032] The optical path allocation control unit 330 included in the optical network management device 300 is connected to the failure detection unit 410 and the standby path switching control unit 430 included in each optical node device. Here, the optical path allocation control unit 330 constitutes an optical path allocation control means, and notifies the optical node device 401 of the standby path information during a failure, which is the result set by the optical path setting means during a failure. Further, the standby path switching control unit 430 constitutes a standby path information reception means during a failure and receives the standby path information during a failure.

[0033] Fig. 4 shows the configuration of the bandwidth variable optical transponder 420. The bandwidth variable optical transponder 420 includes a client interface 421, a bandwidth variable unit 422, and an optical transmission / reception device 423.

[0034] When the bandwidth variable optical transponder 420 receives a standby path switching control signal S1 from the standby path switching control unit 430, the bandwidth variable unit 422 changes the number of wavelength slots according to the bandwidth guarantee rate, and the optical transmission / reception device 423 changes the occupied wavelength slots and the modulation method. When the bandwidth guarantee rate is less than 100%, the bandwidth variable unit 422 sends a backpressure signal S2 to the client interface 421 to perform bandwidth control of the client signal.

[0035] The large-granularity variable switching device 440 is connected to an optical fiber communication line and changes the input / output path in units of optical paths. As the large-granularity variable switching device 440, for example, an optical cross-connect device, a bandwidth-variable wavelength selection switch, or the like can be used.

[0036] Next, the operation of the optical network management device 300 according to the present embodiment will be described. FIG. 5 is a flowchart for explaining the operation of the optical network management device 300 according to the present embodiment.

[0037] In the optical network management device 300, first, the route search unit 321 extracts communication traffic requests between the same nodes in the order of arrival from the request traffic DB 311 (step S210). The route search unit 321 refers to the route information stored in the network facility DB 312 and searches for all non-overlapping routes (physical routes) connecting the start node and the end node of the extracted traffic request (step S220). At this time, as the search algorithm, a k-th shortest path algorithm, a linear programming method, or the like can be used.

[0038] Subsequently, the smaller value of the number of operating paths corresponding to the traffic request and the number of route searches at this time is set as the distributed route number of the standby path (step S230). Here, the distributed route number is the number of route candidates when the standby paths are distributed and arranged. By arranging the standby paths on distributed routes, even when failures occur simultaneously in a plurality of routes, it becomes possible to accommodate the optical paths affected by the failures in the remaining standby paths. Thereby, it is possible to achieve failure recovery at the time of multiple failures and avoid interruption of communication.

[0039] Next, the wavelength slot / fiber allocation determination unit 322 determines the number of wavelength slots and the modulation method for accommodating the communication traffic request based on the link quality of the route (step S240). At this time, the route with the best link quality is set as the operating path, and the remaining route group is set as the standby path.

[0040] The wavelength slot - fiber allocation determination unit 322 checks whether there are available wavelength slots for establishing communication (step S250). If there is a shortage of available wavelength slots (step S250 / NO), after adding fibers (step S260), it allocates an optical path to the available wavelength slots (step S270). Then, it saves the optical path allocation result in the optical path management DB313.

[0041] After determining the allocation of optical paths for all traffic requests managed by the request traffic DB311 (step S280 / NO), the optical path design unit 320 notifies the optical path allocation control unit 330 of the optical path allocation result. The optical path allocation control unit 330 notifies each optical node device 401 - 406 of the optical path design result (step S290).

[0042] Each of the optical node devices 401 - 406 sets its respective operation based on the optical path design result of the optical network management device 300.

[0043] Note that it is desirable for the optical network management device 300 to control the allocation of protection paths to distributed paths with substantially the same link quality. This is because if the link quality is different for the same service, the service quality will deteriorate due to the delay between optical paths. In this case, the modulation method and the like of the optical links of the protection paths can be set to the same method. Therefore, the number of management parameters can be reduced, and it becomes possible to realize a high - speed switching of optical paths when multiple failures occur.

[0044] Next, the failure recovery operation in the optical communication system 2000 according to this embodiment will be described.

[0045] Figures 6A and 6B schematically show the configuration of the optical communication system 2000 according to this embodiment. Figure 6A shows the normal state, and Figure 6B shows the configuration of the optical communication system 2000 when multiple failures occur.

[0046] As shown in Fig. 6A, taking the case of setting optical path protection for two traffic requests W301 and W302 between the optical node device 401 and the optical node device 406 as an example, it will be described. As shown in Fig. 7, the standby paths B301 and B302 for the two traffic requests W301 and W302 are assigned to non-overlapping paths with each other. That is, the standby path B301 is assigned to a physical path passing through the optical node devices 401, 402, 403, and 406. On the other hand, the standby path B302 is assigned to a physical path passing through the optical node devices 401, 404, 405, and 406.

[0047] As shown in Fig. 6B, when failures occur simultaneously on multiple paths between the optical node device 401 and the optical node device 406, and between the optical node device 404 and the optical node device 405, the working paths W301 and W302, and the standby path B302 are interrupted. The failure recovery operation in this case will be described using the sequence diagram of Fig. 8.

[0048] The optical network management device 300 first notifies each of the optical node devices 401 to 406 of the optical path setting (step S310). After that, when a multiple failure occurs, the failure detection units 410 provided in the optical node device 401 and the optical node device 406 respectively notify the optical path allocation control unit 330 of the optical network management device 300 of the occurrence of the failure (step S320). Upon receiving the failure occurrence notification, the multiple-failure-time wavelength slot number determination unit 323 provided in the optical network management device 300 refers to the multiple-failure-time bandwidth guarantee rate DB314 to determine the wavelength slot allocation of the standby path during the multiple failure (step S330). Then, the optical path allocation control unit 330 provided in the optical network management device 300 notifies the standby path switching control units 430 provided in the optical node devices 401 and 406 of the set value of the wavelength slot allocation of the standby path. After that, the standby path switching control units 430 provided in the optical node device 401 and the optical node device 406 respectively control the bandwidth variable optical transponder 420 and the large-granularity variable switching device 440 to activate the standby path of the failed optical path (step S340).

[0049] As shown in FIG. 7, in the optical communication system 2000 of the present embodiment, it is assumed that the bandwidth guarantee ratios during the occurrence of multiple failures are both set to 50% for the operation paths W301 and W302. In this case, if the number of wavelength slots of the operation path is two, the number of wavelength slots during the occurrence of multiple failures is one, which is half of the operation path. Therefore, two spare paths each having one slot can be accommodated in the path where no failure has occurred in FIG. 6B, that is, the path passing through the optical node device 402 and the optical node device 403, for the operation paths W301 and W302.

[0050] Thus, in the optical communication system 2000 according to the present embodiment, the spare paths are dispersedly arranged on a plurality of physical paths that do not overlap with each other. And when failures occur simultaneously in the plurality of physical paths, the number of wavelength slots of the spare paths is reduced according to the bandwidth guarantee ratio during the occurrence of multiple failures, so as to accommodate the failed spare paths. Thereby, it is possible to recover from a multiple failure without causing a decrease in the utilization efficiency of the optical network. As a result, communication interruption can be prevented.

[0051] When the remaining wavelength resources are insufficient for the required number of wavelength slots based on the bandwidth guarantee ratio during a multiple failure, the connectivity of communication can be maintained by setting the wavelength resources allocated to each optical path to be below the guarantee ratio. Also, when priorities are provided for traffic requests, it may be possible to perform failure recovery corresponding to the remaining wavelength resources by rejecting traffic requests with low priorities. In parallel with these processes, wavelength resources for failure recovery may be secured by a restoration method in which the path is recalculated during a failure. After that, it is possible to redesign the spare path so as to satisfy the bandwidth guarantee ratio during a multiple failure.

[0052] Conversely, when there is an excess of remaining wavelength resources with respect to the required number of wavelength slots based on the multi-disability time-band guarantee rate, the excess remaining wavelength resources can be equally divided and allocated for each traffic demand. Further, when a priority is defined for the traffic demand, it may be possible to perform weighting according to the priority and allocate the excess wavelength resources.

[0053] 〔Third Embodiment〕 Next, a third embodiment of the present invention will be described. FIG. 9 shows the configurations of an optical network management device 300 and an optical node device 402 that constitute an optical communication system 3000 according to this embodiment.

[0054] The optical network management device 300 includes a database unit 310, an optical path design unit 320, and an optical path allocation control unit 330. This configuration is the same as that of the optical network management device according to the second embodiment.

[0055] The optical node device 402 includes a failure detection unit 410, a bandwidth-variable optical transponder 420, a standby path switching control unit 430, and a large-granularity variable switching device 440. The configuration up to this point is the same as that of the optical node device 401 according to the second embodiment. The optical node device 402 according to this embodiment further includes a standby path setting management unit 450 in addition to these.

[0056] The standby path setting management unit 450 includes a standby path setting DB 451 and a standby path pre-design I / F (interface) 452. The standby path setting DB 451 constitutes a failure-time standby path information recording means and pre-records failure-time standby path information. Then, using the failure-time standby path information recorded by the standby path setting DB 451 as the failure-time standby path information recording means, a configuration is adopted in which the bandwidth-variable optical transponder 420 as the optical transmission / reception means transmits and receives optical signals.

[0057] Fig. 10 shows an example of the content recorded in the standby path setting DB 451. The standby path setting DB 451 holds the bandwidth guarantee rate and required wavelength slots of the standby path, and the failure recovery path for each assumed failure occurrence pattern. When the number of failure occurrence patterns becomes enormous, the optical network management apparatus 300 may be configured to sequentially update the standby path setting DB 451. Thereby, an increase in the memory capacity of the standby path setting DB 451 can be avoided. Note that it is also possible to record the connection ports of the large granularity variable switching apparatus 440 as the failure recovery path.

[0058] Next, the operation at the time of failure occurrence in the optical communication system 3000 according to the present embodiment will be described. Fig. 11 is a sequence diagram for explaining the operations of the optical network management apparatus 300 and the optical node apparatus 402 included in the optical communication system 3000 of the present embodiment.

[0059] First, the optical network management apparatus 300 notifies each optical node of the calculation result of the optical path setting (step S410). Thereafter, the failure occurrence pattern of the optical path already assigned to the optical node apparatus 402 is calculated up to the occurrence of an m-fold failure (step S420). Here, "m" is an integer of 0 or more, and it is desirable that it is at least 2 or more. Then, for each assumed failure occurrence pattern, the path and wavelength slots of the standby path remaining without being affected by the failure are calculated (step S430). At this time, among the resources of the standby path, the path and wavelength slots of the standby path capable of securing the number of required wavelength slots based on the bandwidth guarantee rate during the multiple failure period are calculated. The optical network management apparatus 300 notifies the standby path pre-design I / F 452 included in the optical node apparatus 402 of the setting of the optical path for multiple failure recovery. The standby path pre-design I / F 452 stores this setting in the standby path setting DB 451 (step S440).

[0060] When the preliminary path pre - setting I / F 452 receives a failure occurrence notification from the failure detection unit 410 (step S450), it refers to the preliminary path setting DB 451 and notifies the preliminary path switching control unit 430 of the preliminary path setting that matches the corresponding failure occurrence pattern (step S460). Based on this setting notification, the preliminary path switching control unit 430 changes the settings of the bandwidth - variable optical transponder 420 and the large - granularity variable switching device 440 (step S470) to perform failure recovery. Thereafter, each time a failure occurs, the operations of steps S460 and S470 are sequentially performed.

[0061] Next, when an (m - k)-fold failure occurs (step S500), the preliminary path pre - design I / F 452 provided in the optical node device 402 requests the optical network management device 300 to calculate the preliminary path setting in the case of an (m + 1)-fold failure (step S510). Here, "k" is an integer value of 0 or more and less than m. The value of "k" can be determined in consideration of the time required for the preliminary path setting and the memory capacity installed in each optical node device. By recalculating the preliminary path setting when the number of failure occurrences becomes (m - k), communication interruption can be avoided.

[0062] At this time, the optical network management device 300 calculates the pattern in which a failure occurs for the optical path already assigned to the optical node device 402 (step S520). Thereafter, for the assumed failure occurrence pattern, it calculates the path and wavelength slots of the preliminary paths that remain without being affected by the failure (step S530). At this time, among the resources of the preliminary paths, it calculates the paths and wavelength slots of the preliminary paths that can secure the required number of wavelength slots based on the multi - failure time - band guarantee rate.

[0063] The subsequent operations are the same as those from step S440 to step S470. That is, the optical network management unit 300 notifies the preliminary path pre-design I / F 452 provided in the optical node device 402 of the setting of the optical path for multiple fault recovery. The preliminary path pre-design I / F 452 stores this optical path setting in the preliminary path setting DB 451. The preliminary path switching control unit 430 performs fault recovery by changing the settings of the bandwidth variable optical transponder 420 and the large granularity variable switching device 440 based on the preliminary path setting that matches the corresponding fault occurrence pattern.

[0064] When the optical path setting is changed by adding or deleting a new optical path or by list restoration, the optical network management device 300 appropriately notifies the preliminary path setting management unit 450 provided in each optical node device of the changed optical path setting. Then, the preliminary path setting management unit 450 updates the preliminary path setting DB 451.

[0065] As described above, the optical communication system 3000 according to the present embodiment is configured such that the optical node device 402 includes the preliminary path setting management unit 450. Therefore, it is possible to set the preliminary path at high speed when multiple faults occur without being affected by the delay in the optical network management device 300.

[0066] As described above, in the optical communication system 3000 according to the present embodiment, the preliminary paths are dispersedly arranged on a plurality of physical paths that do not overlap with each other. And when faults occur simultaneously on the plurality of physical paths, the number of wavelength slots of the preliminary path is reduced according to the bandwidth guarantee rate at the time of multiple fault occurrence to accommodate the affected preliminary path. Thereby, it is possible to achieve fault recovery when multiple faults occur without causing a decrease in the utilization efficiency of the optical network. As a result, communication interruption can be prevented.

[0067] The present invention has been described above by taking the above-described embodiment as an exemplary example. However, the present invention is not limited to the above-described embodiment. That is, the present invention can apply various aspects that can be understood by those skilled in the art within the scope of the present invention.

Description of Symbols

[0068] 1000, 2000 Optical communication system 100, 300 Optical network management device 110 Optical path setting means 120 Optical path setting means in case of failure 200, 401 - 406 Optical node device 210 Optical transmission / reception means 310 Database section 311 Request traffic DB 312 Network facility DB 313 Optical path management DB 314 Band guarantee rate DB in case of multiple failures 320 Optical path design section 321 Route search section 322 Wavelength slot - fiber allocation determination section 323 Number of wavelength slots determination section in case of multiple failures 330 Optical path allocation control section 410 Failure detection section 420 Bandwidth - variable optical transponder 421 Client interface 422 Bandwidth - variable section 423 Optical transmission / reception device 430 Standby path switching control section 440 Large - granularity variable switching device 450 Standby path setting management section 451 Standby path setting DB 452 Standby path pre - design I / F

Claims

1. Optical path setting means for setting a plurality of operating paths in a first physical path, and setting different backup paths corresponding to each of the plurality of operating paths in a plurality of different physical paths different from the first physical path, respectively; When a failure occurs in a plurality of paths including the operating path among the operating path and the backup path, among the plurality of different physical paths, a physical path different from the physical path in which the plurality of paths where the failure has occurred are set, and failure-time optical path setting means for setting including an optical path in which the bandwidth of the backup path is changed; and an optical network management device comprising: An optical node device comprising optical transmission / reception means for transmitting and receiving an optical signal based on the optical path setting set by the failure-time optical path setting means; An optical communication system having the above.

2. The optical transmission / reception means includes at least one of a bandwidth variable transponder and a switching device capable of changing input / output paths in units of optical paths. The optical communication system according to claim 1.

3. The switching device includes at least one of a wavelength selection switch and an optical cross-connect device. The optical communication system according to claim 2.

4. The change in the bandwidth includes at least one of a change in the number of wavelength slots and a change in the modulation method. The optical communication system according to any one of claims 1 to 3.

5. The change in the bandwidth is performed based on at least one of the bandwidth guarantee rate at the time of failure occurrence and the priority of the traffic request. The optical communication system according to any one of claims 1 to 4.

6. Based on the priority, rejection of a traffic request with a low priority or allocation of wavelength resources according to the priority is performed. The optical communication system according to claim 5.

7. The optical path setting means sets a plurality of backup paths corresponding to each of the plurality of operating paths in physical paths having substantially the same communication quality. The optical communication system according to any one of claims 1 to 6.

8. The optical node device changes the number of wavelength slots of the optical path according to the traffic capacity and transmits and receives an optical signal. The optical communication system according to any one of claims 1 to 7.

9. Set a plurality of operating paths in a first physical path, and set different backup paths corresponding to each of the plurality of operating paths in a plurality of different physical paths different from the first physical path, respectively. When a failure occurs in a plurality of paths including the operation path out of the operation path and the standby path, among the plurality of different physical paths, a physical path different from the physical path in which the plurality of paths where the failure has occurred are set is set to include an optical path in which the bandwidth of the standby path is changed. Perform transmission and reception of optical signals based on the optical path setting set at the time of the failure. An optical communication method at the time of failure.

10. The change in the bandwidth includes at least one of a change in the number of wavelength slots and a change in the modulation method. The optical communication method at the time of failure according to claim 9.

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