Optical path design device and optical path design method

Abstract

This optical path design device (10) comprises: an optical path design unit (11A) that preferentially executes one among a route adjustment unit (11B) for designing a new optical path changed from a shortest route to another accommodation route when a designated wavelength is not available on the shortest route connecting both end points in the shortest manner, and a wavelength adjustment unit (11C) for adjusting the use of the designated wavelength between a new optical path and an existing optical path to design the new optical path; and an output unit (12B) that outputs the execution result of the optical path design unit (11A) to each node of an optical NW (20) whereby the new optical path corresponding to an optical path setting request is created.

Description

Optical path design device and optical path design method

[0001] The present invention relates to an optical path design device and an optical path design method.

[0002] The realization of an all-optical network capable of optical path connections at both ends (E2E: End to End) is becoming a reality, and studies are being conducted to provide optical paths in E2E. Non-Patent Document 1 proposes a route design method for connecting domains via direct optical connections by specifying wavelengths that can be used in common between different network domains. This will support optical path design in a multi-domain environment such as inter-operator connections.

[0003] Liufei Xu et al., “Hierarchical Reinforcement Learning in Multi-Domain Elastic Optical Networks to Realize Joint RMSA”, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 41, NO. 8, pp.2276-2288, APRIL 15, 2023

[0004] If the wavelength specified in the shortest route for a new optical path request is already being used by another optical path, one of the following measures is required: ・Change the shortest route to a different route and create an optical path using the specified wavelength. ・Do not change the shortest route, but create an optical path with wavelength adjusted so that the specified wavelength does not collide with the wavelength of another optical path.

[0005] However, adopting a route change as a solution increases the route length and delay time. On the other hand, adopting wavelength tuning incurs the cost of providing a wavelength conversion function within the network. Meanwhile, conventional technologies such as Non-Patent Document 1 do not propose a means for appropriately selecting which solution to use.

[0006] Therefore, the main object of the present invention is to design an optical path using an appropriate method when there is no available wavelength on the shortest path for a specified wavelength.

[0007] In order to solve the above problems, the optical path design device of the present invention comprises the following means: an input unit that receives an optical path setting request including information on both endpoints and information on a designated wavelength for a new optical path to be set in an optical network, an optical path design unit that prioritizes the execution of one of a route adjustment unit that, if the designated wavelength is not available on the shortest route connecting the two endpoints in the shortest time, designs the new optical path by changing the shortest route to another accommodated route, and a wavelength adjustment unit that designs the new optical path by adjusting the use of the designated wavelength between the new optical path and existing optical paths, and an output unit that creates the new optical path in response to the optical path setting request by outputting the execution result of the optical path design unit to each node of the optical network.

[0008] According to the present invention, when there is no available wavelength on the shortest path for a specified wavelength, an optical path can be designed using an appropriate method.

[0009] 1. A configuration diagram of an optical path system according to the present embodiment. 2. A configuration diagram of an optical path design device according to the present embodiment. 3. A hardware configuration diagram of the optical path design device according to the present embodiment. 4. A flowchart showing the processing of the optical path design device according to the present embodiment. 5. A flowchart showing details of wavelength adjustment priority processing according to the present embodiment. 6. A flowchart showing details of route adjustment priority processing according to the present embodiment. 7. A diagram explaining the cost of accommodation routes according to the present embodiment. 8. A configuration diagram showing an example of the topology of an optical network according to the present embodiment. 9. A configuration diagram of an optical path information DB according to the present embodiment. 10. A table storing routes of optical paths designed by an optical path design unit according to the present embodiment using K-Shortest Path. 11. A table storing routes of optical paths corresponding to the table of FIG. 10 according to the present embodiment. 12. A table obtained by extending the table of FIG. 11 according to the present embodiment.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] FIG. 1 is a configuration diagram of an optical path system 100. The optical path system 100 is configured by an optical network 20, in which nodes indicated by circles are connected by links, and an optical path design device 10 that manages the optical network 20, connected by a network. The nodes of the optical network 20 are OXC (Optical Cross Connect) devices, and at least one node further has a wavelength conversion function. The optical network 20 serves as a backbone network such as an IP communication network, and realizes communication using optical signals. The optical network 20 may be a single-carrier network or a multi-domain environment in which multiple carrier networks are connected.

[0012] The optical path design device 10 receives an optical path setting request from a user 9 to create a new optical path (an optical path to be accommodated), and designs an optimal ground-to-ground optical path in response to the optical path setting request. The optical path setting request specifies information on the start and end nodes (ground) of the new optical path, and information on the designated wavelength to be used by the new optical path.

[0013] When the wavelength specified in the optical path setting request is used by an existing optical path (accommodated optical path) on the connection path (shortest path) between the locations of the optical path setting request, the optical path design device 10 enables an optical path connection via direct optical connection by executing the following countermeasures by the route adjustment unit 11B or wavelength adjustment unit 11C. The route adjustment unit 11B in FIG. 2 changes the connection path between the locations of the optical path setting request from the shortest path to another path, and creates a new optical path using the specified wavelength that is not used by any existing optical path. Furthermore, the route adjustment unit 11B may improve wavelength utilization efficiency by considering priorities based on wavelength utilization status and path length from multiple alternative route candidates. The wavelength adjustment unit 11C in FIG. 2 does not change the connection path between the locations of the optical path setting request from the shortest path, but instead creates an optical path adjusted to prevent collisions between the new optical path and existing optical paths for the specified wavelength in the optical path setting request, and derives the accommodated wavelength of the optical path.

[0014] Furthermore, the wavelength tuning unit 11C performs one of the following countermeasures to adjust the wavelengths of the new optical path and the existing optical paths. These countermeasures are performed by the wavelength tuning unit 11C controlling the wavelength conversion function of the nodes of the optical NW 20. The wavelength conversion unit 11C1 in FIG. 2 does not change the wavelength used by the existing optical path from the designated wavelength, but changes the wavelength used by the new optical path from the designated wavelength to the accommodated wavelength. The wavelength defragmentation unit 11C2 in FIG. 2 changes the wavelength used by the existing optical path from the designated wavelength, and sets the vacant designated wavelength as the accommodated wavelength of the new optical path.

[0015] Furthermore, the optical path design device 10 may optimize the use of the wavelength tuning unit 11C by referring to usage constraints of the wavelength tuning unit 11C, such as the equipment cost of wavelength conversion by the wavelength conversion unit 11C1 and the impact on services provided by existing optical paths by the wavelength defragmentation unit 11C2. For example, the wavelength tuning unit 11C determines whether a change in the wavelength used by an existing optical path will affect services on the existing optical path. This determination is made, for example, during maintenance of the network or the optical path to be defragmented, by determining whether services on the existing optical path will be affected. If it is determined that services will not be affected, the wavelength defragmentation unit 11C2 converts the designated wavelength used by the existing optical path to a different wavelength, so that the new optical path will use the designated wavelength. If it is determined that services will be affected, the wavelength conversion unit 11C1 sets the wavelength used by the new optical path to an accommodated wavelength λ different from the designated wavelength.

[0016] As a result, the optical path design device 10 not only enables optical path connections by direct optical coupling, but also reduces the equipment cost for wavelength conversion in the wavelength conversion unit 11C1 and suppresses the impact on existing services in the wavelength defragmentation unit 11C2. Furthermore, the optical path design device 10 prioritizes wavelength defragmentation processing that converts the designated wavelength used by an existing optical path into a different wavelength, thereby reducing the number of times that wavelength conversion processing is used to change the wavelength used by a new optical path from a designated wavelength to an accommodated wavelength.

[0017] 2 is a configuration diagram of the optical path design device 10. The optical path design device 10 has a processing unit 11 (optical path design unit 11A, route adjustment unit 11B, wavelength adjustment unit 11C), an input / output unit 12 (input unit 12A, output unit 12B), and a storage unit 13 (topology information DB 13A, optical path information DB 13B, wavelength information DB 13C). Note that the optical path design device 10 may be configured as a single device, or may be configured with its functions distributed across multiple devices.

[0018] The input unit 12A accepts input of an optical path setting request (demand information for a new optical path) that has arrived at the optical path design device 10 and stores it in the storage unit 13. That is, when the input unit 12A receives an optical path setting request that includes information on both endpoints and information on a specified wavelength for a new optical path to be set in the optical NW 20, the input unit 12A causes the optical path design unit 11A to create a new optical path. The output unit 12B outputs the execution result of the optical path design unit 11A. That is, the output unit 12B creates a new optical path in response to the optical path setting request by outputting the execution result of the optical path design unit 11A to each node of the optical NW 20.

[0019] The optical path design unit 11A designs a new optical path (route and wavelength) in response to a specified optical path setting request based on information stored in the storage unit 13. Therefore, the optical path design unit 11A prioritizes the execution of either the route adjustment unit 11B or the wavelength adjustment unit 11C described below. The route adjustment unit 11B adjusts the route of a new optical path in response to a request from the optical path design unit 11A, as described in FIG. 1. Specifically, if the specified wavelength is not available on the shortest route connecting both end points in the shortest distance, the route adjustment unit 11B designs a new optical path by changing the shortest route to another accommodation route i. The wavelength adjustment unit 11C adjusts the use of the specified wavelength between the new optical path and existing optical paths in response to a request from the optical path design unit 11A, as described in FIG. 1.

[0020] The topology information DB 13A records information indicating the connection relationships between nodes and links in the optical NW 20 and information indicating the distances between nodes as topology information of the optical NW 20. The optical path information DB 13B stores optical path setting requests accepted by the input unit 12A. The wavelength information DB 13C records the wavelength allocation status of each link constituting the optical NW 20.

[0021] 3 is a hardware configuration diagram of the optical path design device 10. The optical path design device 10 is configured as a computer 900 having a CPU 901, RAM 902, ROM 903, HDD 904, communication I / F 905, input / output I / F 906, and media I / F 907. The communication I / F 905 is connected to an external communication device 915. The input / output I / F 906 is connected to an input / output device 916. The media I / F 907 reads and writes data from a recording medium 917. Furthermore, the CPU 901 controls each unit by executing a program (optical path design program) loaded into the RAM 902. This program (also called an application, or an app for short) can be distributed via a communication line or recorded on a recording medium 917 such as a USB memory.

[0022] 4 is a flowchart showing the processing of the optical path design device 10. The input unit 12A receives an optical path setting request (S11) from the user 9, specifying information on the start and end nodes (grounds) of a new optical path and information on the designated wavelength to be used by the new optical path, and stores the request in the optical path information DB 13B. If the designated wavelength of the optical path setting request is not used by an existing optical path on the connection path (shortest path) between the grounds in the optical path setting request, the optical path design unit 11A creates a new optical path at the designated wavelength of the shortest path. This new optical path is an optical path of the designated wavelength that connects the grounds in the optical path setting request via the shortest path, and information for causing the optical NW 20 to create the optical path is output from the output unit 12B.

[0023] On the other hand, if the specified wavelength is being used by an existing optical path on the shortest route, the optical path design unit 11A determines whether to give priority to the wavelength tuning unit 11C (S12). If the answer is Yes in S12, the optical path design unit 11A causes the wavelength tuning unit 11C to design an optical path with priority given to wavelength tuning (S13, details in FIG. 5). If the answer is No in S12, the optical path design unit 11A causes the route tuning unit 11B to design an optical path with priority given to route tuning (S14, details in FIG. 6).

[0024] The determination process in S12 is executed, for example, based on the following policy: The administrator manually inputs a setting to determine whether wavelength tuning is prioritized (Yes in S12) or route tuning is prioritized (No in S12). Having the route adjustment unit 11B perform route adjustment may increase the route length and delay time, which may result in not satisfying the service quality requirements (specified in the optical path setting request) of the user 9. In this case, wavelength tuning is prioritized (Yes in S12). Having the wavelength adjustment unit 11C perform wavelength adjustment may incur costs for using the wavelength tuning function in the optical NW 20, which may not satisfy the operator's cost requirements. In this case, route adjustment is prioritized (No in S12). The cost of using the wavelength tuning function is calculated, for example, from the equipment cost of the wavelength tuning function when the wavelength conversion unit 11C1 is used and the cost of the impact on the service of the existing path when the wavelength defragmentation unit 11C2 is used.

[0025] 5 is a flowchart showing details of the wavelength adjustment priority process (S13). The optical path design unit 11A determines whether the wavelength tuning unit 11C is available (wavelength adjustable) (S131). The wavelength tuning unit 11C is available when, for example, the wavelength conversion function provided by a node in the optical network 20 has a remaining number of available times. If Yes in S131, proceed to S135; if No, proceed to S132. The optical path design unit 11A refers to the topology information DB 13A and the wavelength information DB 13C and determines whether the specified wavelength of the shortest route is available (S132). If Yes in S132, proceed to S133; if No, the new optical path specified in the optical path setting request is treated as a call loss, and the optical path setting request is rejected (S138).

[0026] The wavelength tuning unit 11C refers to the optical path information DB 13B and the wavelength information DB 13C and assigns the designated wavelength of the shortest route to the new optical path (S133). The output unit 12B outputs an instruction to start using the new optical path of S133 to the optical NW 20 (S134).

[0027] If S131 is Yes, the optical path design unit 11A executes a loop (S135 to S137) in which the accommodated wavelength λ is increased in ascending order (λ = 1, 2, 3, ..., λ_max). Note that in this specification, the wavelength values ​​(λ = 1, 2, 3, ...) are not actual wavelength values, but wavelength numbers assigned in ascending order of wavelength value. The optical path design unit 11A references the topology information DB 13A and the wavelength information DB 13C to determine whether the accommodated wavelength λ of the shortest route is available (S135). If S135 is Yes, the optical path design unit 11A proceeds to S133, where it assigns a new optical path using the available accommodated wavelength λ of the shortest route instead of the designated wavelength of the shortest route (S133). If S135 is No, the optical path design unit 11A determines whether the accommodated wavelength λ is within the search range (λ = 1 to λ_max) using the determination formula "λ + 1 ≦ λ_max" (S136). If the answer is No in S136, no available accommodation wavelength λ was found within the search range of the accommodation wavelength λ, so the process proceeds to S138. If the answer is Yes in S136, the optical path design unit 11A updates the accommodation wavelength λ (λ = λ + 1) (S137) since the next wavelength is also within the search range of the accommodation wavelength λ, and returns to S135.

[0028] 6 is a flowchart showing the details of the route adjustment priority process (S14). The route adjustment unit 11B refers to the topology information DB 13A and the optical path information DB 13B, and derives accommodation routes i (i = 1 to K) for the destination of the optical path setting request using an algorithm for finding K-shortest paths, such as Dijkstra's algorithm, and selects accommodation route i (i-th accommodation route) in ascending order of cost (S140). The cost of accommodation route i is calculated from the wavelength usage status of the links through which accommodation route i passes and the route length of accommodation route i. Thereafter, in S140, the accommodation route with the lowest cost is set to i = 1, and the process proceeds to S141.

[0029] Figure 7 is an explanatory diagram of the cost of accommodation route i. An example is given using the following parameters. - Assume accommodation route i of an optical path connected in the order of nodes A, B, C, and D in the optical network 20, and the route length Rpath, which is the total distance of the route, is set to 50. - The number of wavelengths prepared in the optical network 20 is set to 80. - The number of wavelengths used by links passing through the route is set to 20 wavelengths for link AB, 50 wavelengths for link BC, and 10 wavelengths for link CD. - The maximum number of wavelengths used by links passing through the route is set to λmax, which is 50 wavelengths for link BC.

[0030] The route adjustment unit 11B calculates the optical path cost Cpath for accommodated route i using the following (Equation 1) which refers to the wavelength usage status of the link and the route length: Cpath = Rpath × (1 + α × λmax ÷ λcap) ... (Equation 1) Here, the coefficient α is set to 1, for example. Also, "λmax ÷ λcap" is the wavelength usage rate of the link through which the route passes. For the optical path in Figure 7, Cpath = 50 × (1 + 1 × 50 ÷ 80) = 81.25. Also, the higher the coefficient α, the more the link wavelength usage rate is reflected in the optical path cost, enabling load balancing of accommodated route i.

[0031] In this way, when calculating candidates for accommodation route i requested by the optical path design unit 11A, the route adjustment unit 11B calculates the cost of each accommodation route i based on the route length of accommodation route i and the wavelength utilization rate of the link through which accommodation route i passes, and prioritizes the use of accommodation routes with lower costs for new optical paths. As a result, the optical path design device 10 can improve wavelength utilization efficiency and achieve load balancing among optical paths by preferentially selecting optical paths so as to avoid selecting unstable links with extremely high wavelength utilization rates (links close to being blocked) as much as possible.

[0032] 6, the optical path design unit 11A refers to the topology information DB 13A and the wavelength information DB 13C to determine whether the designated wavelength of the accommodated route i is available (S141). If the result of S141 is Yes, the wavelength tuning unit 11C refers to the optical path information DB 13B and the wavelength information DB 13C to assign the designated wavelength of the accommodated route i to the new optical path (S142). The output unit 12B outputs an instruction to the optical NW 20 to start using the new optical path of S142 (S143).

[0033] If the answer is No in S141, the optical path design unit 11A determines whether or not there exists an accommodation route i+1 in S140 that has the next highest cost after the current accommodation route i, using the determination formula "i+1≦K" (S144). If the answer is Yes in S144, the optical path design unit 11A selects the next accommodation route (i=i+1) (S145) and returns to S141. If the answer is No in S144, the optical path design unit 11A determines whether or not the wavelength tuning unit 11C is available (wavelength adjustable) (S146), as in S131. If the answer is Yes in S146, the accommodation route i is initialized to 1 and the accommodation wavelength λ is initialized to 1, and the process proceeds to S151. If the answer is No, the new optical path specified in the optical path setting request is treated as a call loss, and the optical path setting request is rejected (S147).

[0034] The optical path design unit 11A refers to the topology information DB 13A and the wavelength information DB 13C to determine whether the accommodated wavelength λ of the accommodated route i is available (S151). If the result of S151 is Yes, the process proceeds to S142, where the optical path design unit 11A assigns a new optical path at the available accommodated wavelength λ of the accommodated route i (S142). If the result of S151 is No, the optical path design unit 11A determines whether the accommodated wavelength λ is within the search range using the determination formula "λ+1≦λ_max" (S152). If the result of S152 is Yes, the optical path design unit 11A updates the accommodated wavelength λ (λ=λ+1) (S153) because the next accommodated wavelength λ is also within the search range of the accommodated wavelength λ, and returns to S151.

[0035] If the answer is No in S152, no available accommodation wavelength λ was found within the search range of the accommodation wavelength λ for accommodation route i, so the process proceeds to S154. The optical path design unit 11A determines whether or not there is an accommodation route i+1 of S140 that has the next highest cost after the current accommodation route i, using the determination formula "i+1≦K" (S154). If the answer is Yes in S154, the optical path design unit 11A selects the next accommodation route (i=i+1) (S155) and returns to S151. On the other hand, if the answer is No in S154, the process proceeds to S147.

[0036] 8 is a configuration diagram showing an example of the topology of the optical network 20. The optical network 20 is configured by six nodes (node ​​numbers = 131, 132, 170, 200, 230, 270) connected by links. The nodes are OXC (Optical Cross Connect) devices and have a wavelength tuning function that operates under the control of a wavelength tuning unit 11C. In addition, the distance between the nodes (e.g., 47) is added to the links connecting the nodes (e.g., between node numbers = 131 and 132).

[0037] 9 is a diagram showing the configuration of the optical path information DB 13B. The optical path information DB 13B stores an optical path ID, an optical path name, a start node, an end node, a bandwidth, a wavelength used, and an assigned route in association with each optical path setting request. The initial value of the wavelength used is the specified wavelength.

[0038] 10 shows a table 101 that stores the routes of optical paths designed by the optical path design unit 11A using the K-Shortest Path. The table 101 associates optical path routes (via link "1," via link "2," and via link "3") with the path length Rpath in order of shortest path length. Via link "1" is the first link to be traversed from the starting point.

[0039] Fig. 11 shows a table 102 that stores the routes of optical paths corresponding to the table 101 in Fig. 10. Table 102 is associated using the "route order" of table 101 as a key, and associates the maximum value λmax of the number of wavelengths in use (maximum number of wavelengths in use) of links passing through in table 101, the number of wavelengths λcap, and the optical path cost Cpath (cost). As described in Fig. 7, the optical path design unit 11A calculates the optical path cost Cpath for each optical path by taking into consideration the wavelength usage status (maximum value λmax and number of wavelengths λcap) and the path length Rpath as priorities (Equation 1).

[0040] FIG. 12 shows table 103, which is an extension of table 102 in FIG. 11 . In table 103, a new column for "sort order" is added to each column of table 102. The optical path design unit 11A adds the sequence numbers of the "costs" in table 102 to the "sort order" column in ascending order. This allows the optical path design unit 11A to execute a first loop process (S141 → S144 → S145 → S141 . . . ) and a second loop process (S151 → S154 → S155 → S151 . . . ) that selects accommodation routes i in ascending order of cost. For example, in the first iteration of S141, accommodation route i=1 and the third row record with the sort order "1" are selected. In the second iteration of S141, accommodation route i=2 and the first row record with the sort order "2" are selected. In the third iteration of S141, accommodation route i=3 and the second row record with the sort order "3" are selected.

[0041] Hereinafter, various patterns of embodiments will be illustrated, with the shortest route being the first column (route order = 1) in table 103 and the designated wavelength being 2. [First pattern] When the designated wavelength of the shortest route is available. In this case, the optical path design unit 11A creates a new optical path with the designated wavelength = 2 of the shortest route (route order = 1), as explained in S11 of FIG. 4. Alternatively, the optical path design unit 11A creates a new optical path with No in S131 of FIG. 5 → Yes in S132 → the designated wavelength = 2 of the shortest route (route order = 1) (S133).

[0042] On the other hand, the second to fourth patterns shown below are all cases where the specified wavelength of the shortest route is not available. [Second Pattern] The wavelength tuning unit 11C is available, and another wavelength = 1 of the shortest route is available in the wavelength information DB 13C. In this case, the optical path design unit 11A selects Yes in S131 of FIG. 5 → Yes in S135 → creates a new optical path with the accommodated wavelength λ = 1 of the shortest route (route order = 1) (S133).

[0043] [Third Pattern] When the wavelength tuning unit 11C is unavailable but the designated wavelength of route order = 3 is available, the optical path design unit 11A in this case selects Yes in S141 of Fig. 6 and creates a new optical path with designated wavelength = 2 for accommodation route i = 1 (route order = 3 with sort order = 1) (S142).

[0044] [Fourth pattern] When the wavelength tuning unit 11C is available and wavelength 1 of route order = 3 is available, the optical path design unit 11A in this case generates a new optical path with accommodated wavelength λ = 1 of accommodated route i = 1 (route order = 3 with sort order = 1) (S142) as shown in FIG.

[0045] Furthermore, the search order (S141 to S145, S151 to S155) for accommodation routes i for creating a new optical path by the optical path design unit 11A is not limited to the "in order of smallest cost of accommodation routes i" as described above, and any policy may be adopted, such as the order of shortest route length. Similarly, the search order (S135 to S137, S151 to S155) for accommodation wavelengths λ for creating a new optical path by the optical path design unit 11A is not limited to the "in order of smallest wavelength (number) of accommodation wavelength λ" as described above, and any policy may be adopted, such as the order of smallest difference from the designated wavelength.

[0046] [Effect] The optical path design device 10 of the present invention is characterized by having an input unit 12A that receives an optical path setting request including information on both end points and information on the specified wavelength for a new optical path to be set in the optical NW 20; an optical path design unit 11A that prioritizes the execution of either a route adjustment unit 11B that designs a new optical path by changing the shortest route to another accommodated route i when the specified wavelength is not available on the shortest route connecting the both end points; or a wavelength adjustment unit 11C that designs a new optical path by adjusting the use of the specified wavelength between the new optical path and existing optical paths; and an output unit 12B that creates a new optical path in response to the optical path setting request by outputting the execution result of the optical path design unit 11A to each node of the optical NW 20.

[0047] As a result, the optical path design device 10 can design an optical path using an appropriate method when there is no available wavelength on the shortest path for a specified wavelength by selectively combining the route adjustment unit 11B and the wavelength adjustment unit 11C. Furthermore, even in a network in which the optical NW 20 connects multiple operators, an optical path connection by direct optical connection can be realized.

[0048] The present invention is characterized in that the route adjustment unit 11B calculates the cost of each accommodated route i based on the route length of the accommodated route i and the wavelength utilization rate of the link through which the accommodated route i passes, and prioritizes the use of the smaller the cost for a new optical path.

[0049] As a result, the optical path design device 10 can improve wavelength utilization efficiency and achieve load balancing among optical paths by preferentially selecting optical paths so as to avoid unstable links where the wavelength utilization rate of the link is extremely high (the link is close to being blocked).

[0050] The present invention is characterized in that the wavelength adjustment unit 11C determines whether or not a change in the wavelength used by an existing optical path will affect the service on the existing optical path, and if it is determined that the service will not be affected, converts the designated wavelength used by the existing optical path to a different wavelength so that the new optical path will use the designated wavelength, and if it is determined that the service will be affected, sets the wavelength used by the new optical path to an accommodated wavelength λ different from the designated wavelength.

[0051] As a result, the optical path design device 10 can reduce the number of times that the wavelength conversion process is used to change the wavelength used by a new optical path from a specified wavelength to an accommodated wavelength by prioritizing the wavelength defragmentation process, which converts the specified wavelength used by an existing optical path to a different wavelength.

[0052] REFERENCE SIGNS LIST 10 Optical path design device 20 Optical NW 11 Processing unit 11A Optical path design unit 11B Route adjustment unit 11C Wavelength adjustment unit 11C1 Wavelength conversion unit 11C2 Wavelength defragmentation unit 12 Input / output unit 12A Input unit 12B Output unit 13 Storage unit 100 Optical path system

Claims

1. An optical path design device comprising: an input unit that receives an optical path setting request including information on both end points and information on a specified wavelength for a new optical path to be set in an optical network; an optical path design unit that prioritizes the execution of one of: a route adjustment unit that, if the specified wavelength is not available on the shortest route connecting the both end points, designs the new optical path by changing the shortest route to another accommodated route; and a wavelength adjustment unit that designs the new optical path by adjusting the use of the specified wavelength between the new optical path and existing optical paths; and an output unit that creates the new optical path in response to the optical path setting request by outputting the execution results of the optical path design unit to each node of the optical network.

2. The optical path design device according to claim 1, characterized in that the route adjustment unit calculates the cost of each accommodation route based on the route length of the accommodation route and the wavelength utilization rate of the link through which the accommodation route passes, and prioritizes the use of routes with lower costs for the new optical path.

3. The optical path design device of claim 1, wherein the wavelength adjustment unit determines whether a change in the wavelength used by the existing optical path will affect the service on the existing optical path, and if it is determined that the service will not be affected, converts the designated wavelength used by the existing optical path to a different wavelength so that the new optical path uses the designated wavelength, and if it is determined that the service will be affected, converts the wavelength used by the new optical path to an accommodated wavelength different from the designated wavelength.

4. An optical path design device having an input unit, an optical path design unit, and an output unit, wherein the input unit receives an optical path setting request including information on both end points and information on a specified wavelength for a new optical path to be set in an optical network, and the optical path design unit, when the specified wavelength is not available on the shortest route connecting the both end points in the shortest manner, prioritizes either a route adjustment process that changes the shortest route to another accommodated route and designs the new optical path, or a wavelength adjustment process that adjusts the use of the specified wavelength between the new optical path and existing optical paths to design the new optical path, and the output unit creates the new optical path in response to the optical path setting request by outputting the execution result of the optical path design unit to each node of the optical network.

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