JP2010141704A - Optical path rearrangement method and optical communication network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical path rearrangement method with which an optical path can be rearranged so as to optimize a main signal without disconnecting it. <P>SOLUTION: The optical path rearrangement method for rearranging the optical path by changing a node, through which an optical path passes, according to an optimal network configuration, includes steps of: selecting an optical path whose priority becomes maximum from among optical paths on which rearrangement processing has not been performed on the basis of priority set for each optical path (S13); and changing the selected path into an optical path optimized in an optimal network configuration corresponding to the path (S20). Each of the steps is repeatedly executed until all the optical paths are processed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical path rearrangement method and an optical communication network system for rearranging optical paths in an optical communication transmission network.

  In recent years, communication demand has increased dramatically due to advances in communication technology and the spread of IT (Information Technology) services. As a result, the amount of optical paths managed by the optical transmission network and the resource management load of optical paths have increased dramatically in the future. Is expected to increase. In order to improve the resource utilization efficiency of the entire optical transmission network, it is necessary to rearrange regularly set optical path groups to ideal optimal optical path groups.

  When an optical path is added as appropriate according to communication demand, an optical path that is considered to be optimal is allocated via a free wavelength and a node at the time of request. However, since the optical path allocation / release status changes with the passage of time, the overall optical path allocation status is often not always the maximum effective use of resources. There are cases where path assignment is made through a plurality of nodes more than necessary, and it is better to assign another wavelength. In that case, it is desirable from the viewpoint of resource utilization to confirm the state of all optical paths and rearrange them to the optimal optical path allocation state.

  As a conventional optical path rearrangement method for rearranging optical paths in this way, for example, there is a technique described in Patent Document 1 below. In the technique of Patent Document 1 below, as the first stage, an optimal optical path allocation state is created as an optical path optimal arrangement diagram regardless of the optical path setting state currently allocated. Hereinafter, the optical path arrangement diagram is referred to as a network configuration diagram. As a second stage, all or half of the currently assigned optical paths are cut off, and the optical paths for the cut are rearranged in accordance with the optimal optical path layout. When only half of the optical paths are cut, the remaining half of the current optical paths are cut, and optical path rearrangement is performed on the cut optical paths. As described above, this method has a problem that the main signal is disconnected.

  On the other hand, as a conventional optical path rearrangement method that does not involve disconnection of the main signal, for example, there is a technique described in Patent Document 2 below. In this technology, when creating the optimal network configuration diagram in the first stage, the free path of the optical path of the relocation destination optical path is searched, and if it is free, the shortest free optical path is selected. To do. When the optical path is rearranged in the second stage, the main signal can be prevented from being disconnected by switching the main signal to the selected empty optical path.

JP 2006-166316 A Japanese Unexamined Patent Publication No. 7-95207

  However, in the method described in Patent Document 1, the optical path is cut without setting the save destination when the optical path is rearranged. Therefore, there is a problem that the main signal is disconnected and the service to be used is affected. Further, in order to prevent the signal from being disconnected, it is necessary to switch the path after saving the optical path so as not to disconnect the main signal when performing the optical path rearrangement. However, the optical path rearrangement procedure is complicated, so there is a possibility that an error occurs in the procedure. If the optical path is disconnected by mistake, there is a risk that the service of the user is interrupted. There was a problem.

  Further, in the method described in Patent Document 2, the main signal is saved in an empty optical path. Therefore, there is a problem that the rearrangement process is stopped when there is no free optical path in the first stage.

  The present invention has been made in view of the above, and it is an object of the present invention to obtain an optical path rearrangement method and an optical communication network system capable of rearranging optical paths so as to optimize without disconnecting a main signal. Objective.

  In order to solve the above-described problems and achieve the object, the present invention connects an optical signal start point node and an end point node in an optical communication network based on an optimal network configuration generated by a predetermined optimization algorithm. An optical path rearrangement method for rearranging an optical path to be performed by changing a node through which the optical path passes, wherein light that has not been rearranged based on a priority set for each optical path A processing target path selection step of selecting an optical path having the highest priority among the paths as a relocation processing target candidate path; and the relocation processing target candidate path is optimized in the optimal network configuration corresponding to the path Each step is repeated until all the optical paths are processed as candidate paths for the rearrangement process. Characterized in that it.

  According to the present invention, when an optical path having a higher priority is shifted to an ideal optimized path and an optimized path corresponding to the path is currently being used, the next highest priority path is optimized. After that, when the optimized path is currently used, the optical path with the next highest priority is moved to the optimized path first, so the signal is not disconnected. The optical path can be rearranged so as to be optimized.

  Embodiments of an optical path relocation method and an optical communication network system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
1 and 2 are flowcharts showing an example of the processing procedure of the first embodiment of the optical path rearrangement method according to the present invention. FIG. 1 shows an example of a procedure of overall processing for realizing optical path rearrangement, and FIG. 2 shows an example of a procedure of optical path rearrangement execution processing called from the processing of FIG.

  In the optical path rearrangement method according to the present embodiment, optical path rearrangement is realized by a two-step procedure of optimal network configuration calculation processing and optical path selection rearrangement processing. First, the optimum network configuration calculation process will be described. In FIG. 1, it corresponds to the processing of step S11 and step S12. The optimal network configuration is an ideal network configuration with high resource efficiency (ideal network configuration), and a network configuration in which the value of the evaluation function is minimized or maximized using a predetermined evaluation function. It is.

  The ideal network configuration will be described with reference to FIGS. FIG. 3 is a diagram illustrating an example of a network configuration of an unoptimized optical communication network system. The network configuration of FIG. 3 is not optimized and is in a state of poor resource efficiency. As shown in FIG. 3, this network system includes optical transmission apparatuses 1 to 9, and includes an optical transmission apparatus 1 and an optical transmission apparatus 2, an optical transmission apparatus 2 and an optical transmission apparatus 3, an optical transmission apparatus 1 and an optical transmission apparatus. 4, optical transmission device 2 and optical transmission device 5, optical transmission device 3 and optical transmission device 6, optical transmission device 4 and optical transmission device 5, optical transmission device 5 and optical transmission device 6, optical transmission device 4 and optical transmission device 7, optical transmission device 5 and optical transmission device 8, optical transmission device 6 and optical transmission device 9, optical transmission device 5 and optical transmission device 9, optical transmission device 7 and optical transmission device 8, optical transmission device 8 and optical transmission device 9 are connected by a physical path.

  The optical path is a transmission path composed of a plurality of physical paths. Here, it is assumed that three optical paths # 1 to # 3 are defined as follows. An optical path # 1 indicated by a wide dotted line is a transmission path passing through the optical transmission devices 4, 1, 2, 3, 6, 5 and an optical path # 2 indicated by a narrow solid line is an optical transmission device 5 4, 7, and 8, and the optical path # 3 indicated by the solid line are set as transmission paths that pass through the optical transmission devices 5, 8, and 9, respectively. Each optical path uses the same wavelength.

  FIG. 4 is a diagram illustrating an example of an optimized network configuration. The network configuration in FIG. 4 is an optimized ideal network configuration, which is an ideal optimal optical path allocation state with good resource efficiency. In the optical transmission apparatuses 1 to 9, it is assumed that the same path as in the example of FIG. 3 is connected by a physical path.

  In the network configuration of FIG. 4, the optical path # 1 is a transmission path that passes through the optical transmission apparatuses 4 and 5, the optical path # 2 is a transmission path that passes through the optical transmission apparatuses 5 and 8, and the optical path # 3 is an optical transmission. Each is set as a transmission path via the devices 5 and 9. As described above, in the example of FIG. 4, the number of optical transmission apparatuses that each optical path passes is smaller than in the example of FIG.

  Returning to FIG. 1, the operation of the present embodiment will be described. First, a priority evaluation function for obtaining the priority for each of all current optical paths is applied, and the priority order of the optical paths is determined based on the value (evaluation value) of the priority evaluation function for each optical path obtained by application. Set (step S11). For example, when a priority evaluation function is assumed in which an optical path with a high evaluation value becomes an optical path with a high priority, the optical paths are set to have a higher priority in descending order of evaluation value. When using a priority evaluation function in which an optical path with a low evaluation value has a high priority, the optical paths are set to a high priority in order of decreasing evaluation value.

  Specifically, for example, if the priority of the optical path in which the specific service is used is increased, the priority evaluation function F (x: x is the optical path identifier) for the optical path used in the specific service. ) Applies a function that outputs a high numerical value as a result. Also, for example, if the priority is set such that the optical path with higher equipment cost is set to a lower priority, the priority evaluation function F calculates the total cost of the equipment, transponder, transmission line, etc. through the target optical path. , And outputs a value in which the sign of the calculated value is set to minus. In the present embodiment, the number of HOPs (the number of nodes passing between paths at both ends of the optical path) is used as the priority evaluation function F (x). The priority evaluation function F (x) is not limited to this, and may be arbitrarily set according to the system, such as a communication band and a traffic volume record. Further, the priority evaluation function F (x) can be appropriately changed based on the operation status, the priority order, and the like.

  Next, for all the optical paths that have not been relocated, create an ideal network configuration that minimizes the number of HOPs (the number of nodes that pass between the paths at both ends of the optical path) to the minimum (or less than the present) for the entire network. (Step S12). The creation method of the ideal network configuration diagram can adopt a general optimization algorithm, and any creation method may be used, but here, the ideal is given priority from the optical path having a higher priority set in step S11. It is processed so that it is a typical optical path. Here, the number of HOPs is used as the evaluation function G (x) for evaluating the ideal network, as in the priority evaluation function F (x) (G (x) = F (x)). The case where the number of HOPs is minimized in the entire network is defined as an ideal network. However, the present invention is not limited to this, and the evaluation function G (x) for obtaining an ideal network configuration diagram may be arbitrarily set according to the system, such as a communication band and a traffic volume record.

  For example, in the example of FIG. 3, the light path # 1 has the highest number of HOPs = 6 and the highest priority evaluation function value (evaluation value). Next, the light path # 2 is the second highest with HOP = 4, and the optical path # 3 has the lowest evaluation value with the number of HOPs = 3. Therefore, the priority order set in step S11 is the order of optical path # 1, optical path # 2, and optical path # 3. With this priority, an ideal network configuration is obtained in consideration of maximum resource efficiency. It is most desirable to obtain a configuration in which the number of HOPs is minimized as an ideal network configuration, but it is often difficult to obtain a configuration that truly minimizes the network configuration in practice. Therefore, here, a method for obtaining a network configuration that seems to be close to the optimum is adopted, and at least the evaluation value is reduced from the current network configuration. As an example of a method for obtaining a network configuration close to the optimum as described above, there is a conventionally known method such as OSPF (Open Shortest Path First), and among these methods, an appropriate one according to a system request or the like is suitable. Select a method.

  In the example of FIG. 3, the ideal optimum path of the optical path # 1 is a transmission path that passes through the optical transmission apparatuses 4 and 5, and the number of HOPs = 2. The ideal optimum path arrangement of the optical path # 2 is a transmission path that passes through the optical transmission apparatuses 5 and 8, and the number of HOPs = 2. The ideal optimum path arrangement of the optical path # 3 is a transmission path that passes through 5 and 9, and the number of HOPs = 2. The total evaluation value (the number of HOPs) of the ideal optimum path is 13 in the state shown in FIG. 3, whereas it is 6 in the optimized state, and the number of HOPs in the entire network is reduced.

  After the optimal network configuration calculation processing in steps S11 and S12, optical path selection rearrangement processing is executed. First, as a process for selecting an optical path that is a candidate for execution of rearrangement, an evaluation obtained with the current network configuration among unrearranged optical paths (optical paths for which optical path rearrangement execution processing described later has not been completed) The optical path having the largest difference between the value of the function G (x) and the value of the evaluation function G (x) obtained by the ideal network is selected as the highest priority optical path (step S13). At this time, when there are optical paths having the same priority, the optical path having a smaller total sum of the node numbers that pass through is defined as having a higher priority. In the present embodiment, the optical path shifts to the position specified in the ideal network configuration diagram in order from the position where the high priority optical path is currently assigned.

  Next, it is determined whether there is no unarranged optical path (step S14). If there is no unarranged optical path (step S14 Yes), the process proceeds to step S18 described later. If it is determined that there is an unarranged optical path, the path selected in step S13 is set as a target optical path (processing path for the optical path rearrangement execution process), and the optical path is registered in the interference path list (step S15). ). Here, the disturbing path list is a list for storing paths that hinder the transition to the optimum path arrangement.

  Next, the optical path rearrangement execution process (shift to the optimum path) is called and executed with the argument as the target optical path and ERROR-CODE (step S16). Of the arguments of the optical path rearrangement execution process, the former is an argument for identifying the path to be processed by the optical path rearrangement execution process. The input to the optical path rearrangement execution process, ERROR-CODE is the optical path rearrangement execution process. This is the output from the path relocation execution process.

  As the optical path rearrangement execution process (shift to the optimum path), first, as shown in FIG. 2, ERROR-CODE is initialized to 0 (step S21). Next, for the target path, a corresponding ideal optimum optical path is detected from the ideal network configuration diagram as a relocation destination of the target optical path (step S22). Then, it is confirmed whether the ideal relocation destination is not used on the current network configuration diagram (step S23). As a result of the confirmation, it is determined whether an ideal optimum optical path is used in the current network configuration diagram and there is an interfering optical path that prevents rearrangement (step S24).

  If it is determined in step S24 that the ideal optimum optical path is used in the current network configuration diagram and there is a disturbing light path that prevents relocation (Yes in step S24), the relocation of the disturbing light path is performed. It is determined whether the previous optical path overlaps with a path registered in the disturbing path list (step S25). Specifically, the ideal optical path corresponding to the ideal network configuration diagram of the jamming optical path is detected, and whether there is a path that matches the detected path among the paths registered in the jamming path list. to decide.

  When it is determined that the optical path to which the jamming light path is relocated does not overlap with the path registered in the jamming path list (No in step S25), the jamming light path is registered in the jamming light path list (step S26). The disturbing light path is set as the target path (step S27), and the optical path rearrangement execution process is called with the arguments as the target path and ERROR-CODE (step S28). Then, as a result of the optical path rearrangement execution process in step S28, it is determined whether the value of the argument ERROR-CODE to be output is a value indicating a duplication error (step S29).

  If it is not a value indicating a duplication error (No in step S29), the process returns to step S22. If the value indicates a duplication error (Yes in step S29), the optical path rearrangement execution process ends, and the process proceeds to step S17 in FIG.

  If it is determined in step S24 that there is no interfering optical path that prevents rearrangement (No in step S24), the target optical path is changed to an ideal optimum optical path corresponding to that path on the ideal network configuration diagram. Path switching is performed so that the main signal passes through the optimum optical path (step S30). Next, when the target optical path is included in the jamming path list, the target optical path is deleted from the jamming path list (step S31). Then, the target optical path is released (step S32), the optical path rearrangement execution process is terminated, and the process proceeds to step S17 in FIG.

  If it is determined in step S25 that the optical path to which the disturbing optical path is relocated overlaps with the path registered in the disturbing path list (Yes in step S25), ERROR-CODE is set to a value indicating a duplication error. (Step S33), the optical path rearrangement execution process ends, and the process proceeds to Step S17 of FIG.

  When other optical paths have already been set in the ideal optimal optical path path location detected from the ideal network configuration diagram of the migration destination, in order to avoid blocking the signal using that path, The path position of the optimal optical path cannot be set. When another optical path has already been set as a path at the path position of the optimum optical path, the already set path is expressed as a disturbing path for setting the optimized optical path. In the present embodiment, as described above, when there is such a disturbing path based on the determination in step S24, the optical path rearrangement process is recursively called in step S28 with the disturbing path as a processing target. As a result, the disturbing path that hinders the transition is first shifted to the corresponding optimum path in the ideal network configuration diagram.

  Note that the migration destination of the current optical path that is hindering migration (the corresponding optimal path in the ideal network configuration diagram) is still migrated because it has a lower priority than the target optical path to be processed. It should be an optical path that is not in use. Therefore, if there is a current optical path that hinders the transition, the disturbing path that hinders the transition of the high-priority optical path with the low priority is first determined as the target position on the ideal network configuration diagram. It becomes the procedure to move to.

  When the disturbing path that is hindering the transition (referred to as the first disturbing path here) is shifted to the optimum path, it is further changed to the target transition position on the ideal network configuration diagram. There may be cases where an optical path exists and cannot be shifted. In that case, an optical path relocation procedure is called for the path that prevents the transition of the first disturbing path (hereinafter referred to as the second disturbing path), and the transition of the first disturbing path is performed. What is necessary is just to perform the transfer to the optimization path | route of the 2nd obstruction path which is obstructing in the same procedure. In this way, when there is an optical path that hinders the transition on the current network, the procedure for performing the transition first from the hindering optical path is repeated. In the transition from the current optical path to the ideal optimum optical path, when the optical path route partially overlaps, section (partial) switching by only the non-overlapping route may be performed. In this way, if section (partial) switching is performed, the possibility of migration can be expected to increase.

  In addition, when the optical path that hinders the transition is an optical path that has been waiting for the transition in the previous procedure, it may become a deadlock state and cannot be transitioned. Therefore, in the present embodiment, the optical path transition target route is recorded as a disturbing path list, and if a path registered in the disturbing path list is necessary as a transition destination route, deadlock Is determined to have occurred. A duplicate error is set in the error code (ERROR-CODE) and the process returns to the caller. If the error code is 0 (value indicating normality), the caller can determine that the transfer has been successfully completed.

  Returning to the description of FIG. 1, when the optical path rearrangement execution process is called in step S16 and the execution ends, it is determined whether ERROR-CODE is a value indicating a duplication error (step S17). When it is determined that ERROR-CODE is a value indicating a duplication error (Yes in step S17), the process returns to step S12, and an ideal network configuration is obtained again. However, for an optical path that could not be rearranged due to an overlap error, a path different from the optimal optical path obtained in the first step S12, that is, the next ideal optical path becomes the optimal optical path. Step S13 and subsequent steps are executed.

  If it is determined that ERROR-CODE is not a value indicating a duplication error (No in step S17), the process returns to step S13, and the optical path with the highest priority among the optical paths that have not been rearranged is step S13 and subsequent steps. Perform the process.

  If it is determined in step S14 that there is no unrelocated optical path (Yes in step S14), the process ends. In FIG. 1, when it is determined in step S14 that there is no unrearranged optical path (step S14 Yes), the processing of step S18 to step S20 is described as being executed. When performing the optical path rearrangement execution process according to the procedure, the process may be terminated without performing the processes of steps S18 to S20.

  In the optical path rearrangement execution process in FIG. 2, the network configuration after the rearrangement is obtained without executing the actual optical path switching and release process (steps S30 to S32). After confirming the effect after placement (reduction in the number of HOPs), the rearrangement may be executed. In this case, since steps S30 to S32 are not performed, if it is determined in step S14 that there is no unrelocated optical path (Yes in step S14), the number of HOPs in the network configuration before relocation (in the network) The total number of optical path HOPs) N1 is compared with the number of HOPs in the network configuration after relocation (the total number of optical path HOPs in the network) N2 (step S18) to determine whether N1 is greater than N2 (Step S19). If N1 is N2 or less (No in step S19), it is determined that there is no effect of rearrangement, and the process is terminated.

  When N1 is larger than N2 (Yes in step S19), the path is switched so that the rearrangement destination obtained by the optical path rearrangement execution process is performed, and the rearrangement is executed (step S20).

  A specific example of the operation described above will be described with reference to FIGS. FIG. 4 is an ideal network configuration obtained by the above-described optimal network configuration calculation process, with FIG. 3 as the current network configuration. First, when the difference between the evaluation values corresponding to step S13 is obtained in the state of FIG. 3, the optical path # 1 is 4, the optical path # 2 is 2, the optical path # 3 is 1, the optical path # 1, the optical path The path # 2 and the optical path # 3 are selected in this order.

  First, the optical path rearrangement execution process is executed from the highest priority optical path # 1. The transition destination in the ideal network configuration of the optical path # 1 is a path between the optical transmission apparatus 4 and the optical transmission apparatus 5. However, since this path is currently used by the optical path # 2 (state shown in FIG. 3), it cannot be shifted. For this purpose, a process of first shifting the optical path # 2 that hinders the shift of the optical path # 1 is performed. The transition destination in the ideal network configuration of the optical path # 2 is a path between the optical transmission apparatus 5 and the optical transmission apparatus 8. However, the path between the optical transmission apparatus 5 and the optical transmission apparatus 8 is used by the optical path # 3 in the current network configuration.

  Therefore, in order to shift the optical path # 2, it is necessary to shift the optical path # 3 first. The transition destination in the ideal network configuration of the optical path # 3 is a route between the optical transmission device 5 and the optical transmission device 9, but this route is not used in the current network configuration. Therefore, first, a path between the optical transmission apparatus 5 and the optical transmission apparatus 9 is set for the optical path # 3, and the path is switched to a new path between the optical transmission apparatus 5 and the optical transmission apparatus 9. After switching is completed, the old (before switching) optical path # 3 is released. When the old optical path # 3 is released, the path between the optical transmission apparatuses 5-8, which is the transition destination of the optical path # 2, is vacated. Therefore, as the next step, a path between the optical transmission apparatuses 5-8 is set, and the current optical path # 2 is switched to a new path of the transmission path between the optical transmission apparatus 5 and the optical transmission apparatus 8. After completing the switching, the transmission path of the old optical path # 2 is released. If the transmission path of the old optical path # 2 is released, the path between the optical transmission apparatus 4 and the optical transmission apparatus 5 that is the transition destination of the optical path # 1 having a higher priority is opened. Therefore, as a final step, after setting the path between the optical transmission apparatus 4 and the optical transmission apparatus 5, the optical path # 1 is switched to the new optical path 1 in the transmission path section between the optical transmission apparatuses 4-5, and the main signal is switched. To go through the path.

  In the present embodiment, three optical paths having the same wavelength are assumed. However, even when applied to four or more optical paths, the same effect as in the present embodiment can be obtained by the same procedure. Further, the present invention can be similarly applied to a plurality of optical path groups having different wavelengths, and in this case, optical path rearrangement can be performed in parallel in the optical path groups having the same wavelength.

  Furthermore, the present embodiment has shown an example in which the present invention is applied to the lowermost optical path layer of the OSI (Open Systems Interconnection) model, but the same effect can be expected when applied to two or more network layers of OSI. .

  In this way, in the present embodiment, the optical path having a higher priority is shifted to the optimized path, and when the optimized path is currently used, the path with the next highest priority is changed to the optimized path. After that, when the optimized path is currently used, the next highest priority optical path is shifted to the optimized path first. Therefore, the optical path can be rearranged in the optimized ideal network without disconnecting the main signal and without affecting the user of the optical communication service.

Embodiment 2. FIG.
The second embodiment of the optical path rearrangement method according to the present invention will be described below. In the first embodiment, when there is a current optical path that hinders the transition of a high-priority optical path to an ideal optimum optical path, a method of migrating the disturbing optical path to the ideal optimum optical path first showed that. In the case of the method of the first embodiment, when an attempt is made to evacuate a blocking optical path to the optimum optical path, if the current optical path with a higher priority than that path overlaps with the path, the current high priority is used. The ideal optimum optical path shift of the optical path is abandoned, and the next candidate ideal optimum optical path is searched. In the second embodiment, when the ideal optical path transition location of the obstructing optical path overlaps with the current high priority optical path, the obstructing optical path is not optimal but free. It shifts to temporarily retract to another optical path that is the route that is being used. By performing such processing, it becomes possible to shift a higher priority optical path to an ideal optimum optical path.

  FIG. 5 is a flowchart illustrating an example of the procedure of the optical path rearrangement execution process according to the present embodiment. FIG. 6 is a flowchart showing an example of the procedure of the optical path free allocation process called from the optical path rearrangement execution process of the present embodiment of FIG. The overall processing of the present embodiment is the same as that of FIG. 1 except that the optical path rearrangement execution process called in step S16 described in FIG. 1 of the first embodiment is changed to the optical path rearrangement execution process of the present embodiment. This is the same as the overall processing of the first embodiment shown. Hereinafter, a different part from Embodiment 1 is demonstrated.

  The operation of this embodiment will be described. After performing steps S11 to S15 as in the first embodiment, the optical path rearrangement execution process of the present embodiment is called. As shown in FIG. 5, in the optical path rearrangement execution process of the present embodiment, steps S21 to S25 similar to those of the first embodiment are performed. If it is determined in step S25 that the relocation destination optical path of the disturbing optical path overlaps with the path registered in the disturbing path list (Yes in step S25), the free path with the duplication target path and ERROR-CODE as arguments. An allocation process is called (step S40).

  In the free path allocation process, for optical paths that are hindering the transition of the high-priority optical path, abandon the transition to the optimized optical path of the ideal network configuration and route other than the optimized optical path (detour path) In order to attempt to shift to a path of a currently unused optical path in (path), a search for an empty optical path is performed. If an empty optical path can be searched, after setting the path of the empty optical path, the main signal of the low-priority optical path is saved by switching to this empty optical path, and the high-priority light blocked by this optical path is saved. Rearrange the path to the optimal optical path. When the free optical path route cannot be searched, the search is performed in order for the free optical path route with respect to the other lower priority optical paths that are obstructing.

  Next, the empty path allocation processing will be specifically described with reference to FIG. First, ERROR-CODE is initialized to 0 (step S41). Then, the start point and end point of the target optical path are detected from the current network configuration (step S42), and an empty path from the detected start point to end point is searched (step S43). As a free path search method at this time, a route from the start point to the end point extracted using a general shortest path search algorithm such as OSPF is obtained, and it is determined whether the route is a free path. If it is not free, the next route is obtained in the same manner, and it is determined whether or not the route is free. Repeat the above process until a free path is found.

  Then, it is determined whether or not an empty path has been obtained as a search result (step S44). If an empty path can be searched (step S44 Yes), the path from the target optical path (duplicate path in step S25) to the empty path is determined. Switching is performed so that the main signal passes through the empty path (step S45). If the target optical path (the path duplicated in step S25) is included in the disturbing path list, the target optical path is deleted from the disturbing path list (step S46). Then, the target optical path is released (step S47). If a free path cannot be searched (No in step S44), a duplicate error is set in ERROR-CODE (step S48), and the free path allocation process is terminated.

  After the free path allocation process is completed in step S40, the process proceeds to step S29. If it is determined in step S25 in FIG. 5 that the optical path to which the disturbing optical path is relocated does not overlap with the path registered in the disturbing path list (No in step S25), hereinafter, it is the same as in the first embodiment. Similarly, the process after step S26 is performed. The operations of the present embodiment other than those described above are the same as those of the first embodiment.

  A specific example of the operation described above will be described with reference to FIGS. With FIG. 7 as the current network configuration, the ideal network configuration obtained by the above-described optimal network configuration calculation process is shown in FIG. FIG. 7 is a diagram illustrating an example of a network configuration of the optical communication network system according to the present embodiment in an optical path allocation state with poor resource efficiency. FIG. 8 is a diagram illustrating an example of an optimized network configuration. FIG. 8 shows an example in which a network system that is physically similar to FIG. 7 is optimized. The optical network system shown in FIG. 7 includes optical transmission apparatuses 1 to 18, and the physical path is not shown here, but optical transmission apparatus 1 -optical transmission apparatus 2, optical transmission apparatus 2 -optical transmission apparatus 3. It is assumed that adjacent optical transmission devices such as optical transmission device 3 -optical transmission device 4, optical transmission device 4 -optical transmission device 5, optical transmission device 6 -optical transmission device 12, etc. are connected by a physical path. .

  In FIG. 7, two optical paths # 1 and # 2 are set. The optical path # 1 is an optical path between the optical transmission device 9 and the optical transmission device 10, and the optical transmission devices 9, 8, and 2 are set. , 3, 4, 5, 11, and 10 are set as transmission paths. The optical path # 2 is an optical path between the optical transmission device 2 and the optical transmission device 5, and the optical transmission devices 2, 1, 7, 13, 14, 15, 9, 10, 16, 17, 18, 12, 6 , 5 is set.

  On the other hand, in FIG. 8, which is an ideal network configuration example, the optical path # 1 is set as a transmission path via the optical transmission apparatuses 9 and 10. The optical path # 2 is set as a transmission path that passes through the optical transmission apparatuses 2 and 5.

  First, when the difference between the evaluation values corresponding to step S13 is obtained in the state of FIG. 7, the optical path # 1 is selected with the highest priority, and the optical path # 2 is set with the next priority. First, the optical path rearrangement process is executed from the optical path # 1. The migration destination (optimization path) of the ideal network configuration (FIG. 8) of the optical path # 1 is a path between the optical transmission apparatuses 9-10. However, this route is already used by the optical path # 2, and cannot be transferred to this route. For this purpose, the optical path # 2 that hinders the transition of the optical path # 1 is shifted first. In order to perform the transition of the optical path # 2, the path between the optical transmission apparatus 2 and the optical transmission apparatus 5 needs to be free according to the ideal network configuration. However, the path between the optical transmission apparatus 2 and the optical transmission apparatus 5 is used by the current optical path # 1, and cannot be the migration destination.

  For this reason, it is impossible to shift between the optical path # 1 and the optical path # 2 by the method of saving to the optimum optical path because the save destination is occupied by the current optical path. In this embodiment, in such a case, the save destination of the optical path # 2 is searched from the available optical paths by the optical path allocation process. Here, it is assumed that partial switching is possible, and the route section of the optical transmission device 15-9-10-16, which is a part of the optical path # 2, is routed to the route of the optical transmission device 15-16, which is an empty path. Switch to the section. FIG. 9 is a diagram illustrating a state in which the optical path # 2 is shifted to an empty path in this way. By this switching, the optical path # 1 can be shifted to the path of the optical transmission device 9-10 that is the optimized path. FIG. 10 is a diagram illustrating a state in which the optical path # 1 is shifted to the optimized path.

  Then, after the high-priority optical path # 1 is shifted to the optimized path, the optical path rearrangement process of the next priority optical path # 2 is performed as the next procedure. As described above, the optical path # 2 is temporarily retracted to the transmission path section connecting the optical transmission apparatuses 2-1-7-13-14-15-16-17-18-12-6. In the next process (process after step S13), the optical path # 2 can be shifted to the optimized optical path (route of the optical transmission apparatus 2-5). As a result, it is possible to shift from the state shown in FIG. 10 to the ideal network configuration shown in FIG.

  In this embodiment, two optical paths having the same wavelength are assumed, but the same effect can be obtained by the same operation even when applied to three or more optical paths. In addition, the present invention can be similarly applied to a plurality of optical path groups having different wavelengths. In this case, the optical path rearrangement can be performed in parallel in each optical path group having the same wavelength. Further, when searching for an empty section of an optical path, when searching not for a partial search but for an entire search, it is possible to search by switching to a different wavelength, increasing the possibility of realizing optical path switching.

  As described above, in the present embodiment, when there is a current optical path that hinders the transition of a high-priority optical path to an ideal optimum optical path, the ideal optical light is first determined as the obstructed optical path. When migrating to a path, if the path of the migration destination is currently in use, the migration destination of the optical path to be blocked is selected from the available paths. Therefore, it is possible to improve the possibility that the current optical path with high priority can be set as the optimum optical path compared to the first embodiment.

  As described above, the optical path relocation method and the optical communication network system according to the present invention are useful for an optical communication network, and are particularly suitable for an optical communication network having a large number of optical paths.

6 is a flowchart illustrating an example of a procedure of overall processing according to the first embodiment for realizing optical path rearrangement. It is a flowchart which shows an example of the procedure of an optical path rearrangement execution process. It is a figure which shows an example of the network structure of the optical communication network system which is not optimized. It is a figure which shows an example of the optimized network structure. 10 is a flowchart illustrating an example of a procedure of an optical path rearrangement execution process according to the second embodiment. It is a flowchart which shows an example of the procedure of the optical path free allocation process called from an optical path rearrangement execution process. It is a figure which shows an example of the network configuration of the optical communication network system of Embodiment 2 of the optical path allocation state with bad resource efficiency. It is a figure which shows an example of the optimized network structure. It is a figure which shows the state which transferred optical path # 2 to the empty path. It is a figure which shows the state which shifted optical path # 1 to the optimization path.

Explanation of symbols

  1-18 Optical transmission equipment

Claims (11)

In an optical communication network, based on an optimal network configuration generated by a predetermined optimization algorithm, an optical path connecting a start node and an end node of an optical signal is changed by changing a node through which the optical path passes. An optical path rearrangement method for placing,
Based on the priority set for each optical path, a processing target path selection step for selecting, as a rearrangement processing target candidate path, an optical path with the highest priority among the optical paths that have not been rearranged,
Relocation step of changing the relocation processing target candidate path to an optimized optical path in the optimum network configuration corresponding to the path;
Including
An optical path rearrangement method, wherein each step is repeatedly executed until all optical paths are processed as rearrangement process target candidate paths. Path confirmation for determining whether there is a disturbing path that is another optical path in the current network configuration in which the route overlaps with the optimized optical path in the optimal network configuration corresponding to the relocation processing target candidate path Steps,
When it is determined that there is a disturbing path in the path confirmation step, a disturbing light path selection step that performs the path confirmation step again with the disturbing path as the relocation processing candidate path;
Further including
In the rearrangement step, when it is determined in the path confirmation step that no disturbing path exists, the change is performed,
2. The optical path reconfiguration according to claim 1, wherein the disturbing light path selection step that is performed based on the determination result of the path confirmation step that is performed again is repeatedly performed until the rearrangement step is performed. Placement method. In the path confirmation step, when the optimized optical path and the route in the optimal network configuration corresponding to the relocation processing target candidate path partially overlap, a non-overlapping section is set as a partial relocation processing target candidate path,
The optical path rearrangement according to claim 2, wherein in the rearrangement step, the partial rearrangement processing target candidate path is changed to an optimized optical path in the optimal network configuration corresponding to the path. Method. Interfering path recording step for holding the optical path selected in the processing target path selecting step as an interfering path history,
If it is determined that the optimized optical path in the optimal network configuration corresponding to the disturbing path is included in the disturbing path history in the disturbing light path selecting step, the disturbing light path selecting step is interrupted, An optimal network configuration regeneration step for generating an optimal network configuration as an optimal network configuration next to the optimal network configuration that has already been generated based on the optimization algorithm;
If it is determined in the disturbing optical path selection step that the optimized optical path in the optimum network configuration corresponding to the disturbing path is not included in the disturbing path history, the disturbing path is added to the disturbing path history. An obstruction path addition step;
When the rearrangement step is executed, an interference path deletion step of deleting the optical path before switching, which is a target of switching in that step, from the interference path history,
Further including
The optical path rearrangement method according to claim 2 or 3, wherein after the optimization network configuration regeneration step is performed, an iterative process for all the optical paths is executed. Interfering path recording step for holding the optical path selected in the processing target path selecting step as an interfering path history,
If it is determined in the disturbing optical path selection step that the optical path optimized in the optimum network configuration corresponding to the disturbing path is included in the disturbing path history, a route that is not used in the current network configuration is used. A free path allocating step for obtaining an optimal free path corresponding to the disturbing path and changing the disturbing path to the optimal free path;
An optimal network configuration regeneration step for generating, as an optimal network configuration, an optimal network configuration next to the optimal network configuration already generated based on the optimization algorithm when there is no optimal free path corresponding to the disturbing path; ,
If it is determined in the disturbing optical path selection step that the optimized optical path in the optimum network configuration corresponding to the disturbing path is not included in the disturbing path history, the disturbing path is added to the disturbing path history. An obstruction path addition step;
When the rearrangement step is executed, an interference path deletion step of deleting the optical path before switching, which is a target of switching in that step, from the interference path history,
Further including
The optical path rearrangement method according to claim 2 or 3, wherein after the optimization network configuration regeneration step is performed, an iterative process for all the optical paths is executed.   6. The optical path rearrangement method according to claim 1, wherein the priority determination method can be changed.   The priority is determined based on at least one of a route length, a cost required for setting a path, transmission quality, the number of links, and importance of a service to be used. The optical path rearrangement method as described in one.   In the processing target path selection step, for each optical path, an evaluation index value indicating the degree of optimization is obtained based on the path setting of the current network configuration, and the obtained value is set as a first evaluation value. For each path, a value of an evaluation index is obtained based on the path setting of the optimized optical path in the optimum network configuration, the obtained value is set as a second evaluation value, and the priority is set as the first evaluation value. The optical path rearrangement method according to claim 1, wherein the optical path rearrangement method is obtained based on a difference between the second evaluation values.   An optical communication network system, wherein the optical path rearrangement method according to claim 1 is executed.   The optical communication network system according to claim 9, wherein a single optical wavelength is used. Use multiple light wavelengths,
The optical communication network system according to claim 9, wherein the optical path rearrangement method is executed in parallel for each optical path connecting the start node and the end node of the optical signal using the same wavelength.

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