Control device, and program

Abstract

To use the number of wavelength which can be used in an optical network in the maximum.SOLUTION: A control apparatus 100 includes: a storage part 110 that stores control information 111; a monitoring part 120 that monitors an optical mesh network; and a control part 130 that executes a switching of a path and an allocation of a plurality of wavelength on the basis of the control information 111 in the case where a failure is detected in the optical mesh network. The control information 111 indicates: a first rule that indicates an elimination of the path where the failure occurs from the path in a switching destination; a second rule that indicates the allocation of each wavelength so as to avoid a collision of each wavelength in the case of performing a switching-back of the path; and a third rule that indicates an execution of the switching and the allocation of the wavelength by preferentially selecting the path to which an optical signal in which a plurality of optical signals are multiplexed from the plurality of paths in the optical mesh network.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a control device , and a program thereof.

Background Art

[0002] In an optical network, a plurality of optical signals are being communicated. For example, the optical network is described in Patent Document 1. Here, a technique for rearranging the wavelengths of optical signals has been proposed (see Patent Document 2). For example, the network design device of Patent Document 2 rearranges optical lines to each optical wavelength based on design information for arranging optical lines for each optical wavelength in the network.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when a failure occurs in a certain path in the optical network, communication via that path becomes impossible. Therefore, that path is switched to another path. As a result, communication continues. When switching paths, a wavelength different from the wavelength assigned to the path before switching may be assigned to the path after switching. Specifically, wavelength assignment is performed based on rules. However, depending on the content of the rules, the maximum number of wavelengths that can be used in the optical network may not be used to the maximum extent.

[0005] An object of the present disclosure is to use the maximum number of wavelengths that can be used in an optical network.

Means for Solving the Problems

[0006] A control device according to one aspect of the present disclosure is provided. The control device is a control device that switches a path by controlling optical switches included in a plurality of nodes that construct an optical mesh network, and has a control unit that performs path switching and allocation of a plurality of wavelengths based on control information. When a failure is detected in the optical mesh network, the control unit excludes the path where the failure has occurred from the switching destination path, and when the path is switched back, performs wavelength allocation so that wavelengths do not collide, and among a plurality of paths in the optical mesh network, preferentially performs switching and wavelength allocation for a path through which an optical signal in which a plurality of optical signals are multiplexed is communicated, or performs path switching and wavelength allocation in descending order of the number of nodes included in the switched path, performs wavelength allocation based on the First-Fit method, or performs path switching and wavelength allocation in descending order of an evaluation value calculated based on the number of nodes included in the switched path and the bandwidth corresponding to the switched path, and sets the control information to perform wavelength allocation based on the First-Fit method. Alternatively, before a failure occurs in the optical mesh network, when the path is switched back, the control unit performs wavelength allocation so that wavelengths do not collide, and preferentially among a plurality of paths in the optical mesh network, sets the reserved path for the path through which the multiplexed optical signal is communicated and the wavelength to be allocated to the reserved path as the control information.

Effect of the Invention

[0007] According to the present disclosure, the maximum number of wavelengths that can be used in an optical network can be utilized.

Brief Description of the Drawings

[0008] [Fig. 1] It is a diagram showing an optical communication system of Embodiment 1. [Fig. 2] (A) and (B) are diagrams showing Comparative Example (1-1). [Fig. 3] (A) and (B) are diagrams showing Comparative Example (1-2). [Fig. 4] It is a diagram showing the hardware of the control device of Embodiment 1. [Fig. 5] It is a block diagram showing the functions of the control device of Embodiment 1. [Fig. 6] (A) and (B) are diagrams showing a specific example (1-1) of the process executed by the control device of Embodiment 1. [Fig. 7] (A) and (B) are diagrams showing a specific example (1-2) of the process executed by the control device of Embodiment 1. [Fig. 8] It is a diagram showing a specific example (1-3) of the process executed by the control device of Embodiment 1. [Fig. 9] (A) and (B) are diagrams showing Comparative Example (2-1). [Fig. 10] (A) and (B) are diagrams showing Comparative Example (2-2). [Fig. 11] It is a block diagram showing the functions of the control device of Embodiment 2. [Fig. 12] (A) and (B) are diagrams showing a specific example (2-1) of the process executed by the control device of Embodiment 2. [Fig. 13] (A) and (B) are diagrams showing a specific example (2-2) of the process executed by the control device of Embodiment 2. [Fig. 14]It is a diagram showing a specific example (2-3) of the processing executed by the control device of Embodiment 2. [Fig. 15] It is a diagram showing an example when the reserved route of Embodiment 3 is determined. [Fig. 16] (A) and (B) are diagrams showing Comparative Example (3). [Fig. 17] It is a block diagram showing the functions of the control device of Embodiment 3. [Fig. 18] (A) and (B) are diagrams showing a specific example (3) of the processing executed by the control device of Embodiment 3.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to the drawings. The following embodiments are merely examples, and various modifications are possible within the scope of the present disclosure.

[0010] Embodiment 1. FIG. 1 is a diagram showing the optical communication system of Embodiment 1. The optical communication system includes a control device 100 and a plurality of nodes. Further, the optical communication system may include a data center 10 and an SDH (Synchronous Digital Hierarchy) ring 20. The optical mesh network 200 is constructed by a plurality of nodes. The control device 100 monitors a plurality of nodes. Further, the control device 100 controls a plurality of nodes.

[0011] Figure 1 shows that the communication between the data center 10 and the SDH ring 20 is carried out via the optical mesh network 200. For example, the communication between the data center 10 and the SDH ring 20 is carried out via path X1. In the optical mesh network 200, a failure may occur. For example, the failure is a failure of the optical cable existing between nodes. When a failure occurs in the optical mesh network 200, the control device 100 can switch the path by controlling the optical switches of multiple nodes. For example, the control device 100 controls the optical switches of some nodes to switch from path X1 to path X2. Thereby, even when a failure occurs in the optical mesh network 200, the communication between the data center 10 and the SDH ring 20 continues.

[0012] Next, a comparative example will be described. Figures 2(A) and (B) are diagrams showing Comparative Example (1-1). Figure 2 shows nodes A to F. The optical mesh network is constructed by nodes A to F. In the optical mesh network, it is possible to use λ1 to 6 having a wavelength of a bandwidth of 50 GHz.

[0013] The path between nodes A and D is called path R1. Nodes A and D communicate an optical signal of λ1 of 50 GHz. The paths of nodes C, B, E, and F are called path R2. Nodes C, B, E, and F communicate an optical signal of λ4 of 50 GHz and an optical signal of λ5 of 50 GHz. The path of nodes A, B, E, and D is called path R3. Nodes A, B, E, and D communicate an optical signal of λ1-3 of 150 GHz (that is, the total value of the bandwidths of three wavelengths). The optical signal of λ1-3 is a signal in which three optical signals are multiplexed.

[0014] Figure 2(A) shows that a failure has occurred in the paths of nodes A and D and the paths of nodes B and E. Thus, when a failure occurs, in an optical mesh network, the path is switched. Here, the path switching and wavelength allocation are performed based on three rules. First, path switching means a temporary retreat. Therefore, when the failure is overcome, the switched path is returned to the original path. That is, the path is switched back. When the path is switched back, Rule 1 is defined to prevent wavelength collisions. Rule 1 is to perform wavelength allocation so that wavelengths do not collide when the path is switched back. Specifically, when switching back from the first path to the second path in the optical mesh network, a wavelength different from the wavelength assigned to the second path is assigned to at least a part of the second path that is the same path, and the path to be switched is assigned to the third path that has been switched. Rule 2 is to perform wavelength allocation based on a wavelength allocation algorithm (i.e., the First-Fit method). That is, in Rule 2, wavelengths are assigned in ascending order of numbers. Rule 3 is that wavelengths being allocated on other paths cannot be allocated.

[0015] Hereinafter, the case where path switching is performed based on the above three rules will be described. Figure 2(B) shows the state after Figure 2(A). Path R1 is switched to path R4. Path R4 is the path of nodes A, B, C, F, E, D. Based on Rule 1 and Rule 3, λ6 is assigned to path R4.

[0016] Figures 3(A) and (B) are diagrams showing Comparative Examples (1-2). Figure 3(A) shows the state after Figure 2(B). Path R2 is switched to path R5. Path R5 is the path of nodes C and F. Based on Rule 1 and Rule 2, λ1 and λ2 are assigned to path R5.

[0017] Figure 3(B) shows the state after Figure 3(A). When path R3 is switched to the path of nodes A, B, C, F, E, D, λ3-5 is assigned to the path based on Rule 2. Here, when the failure is overcome, path R5 is switched to path R2. λ4 and λ5 are assigned to path R2. λ4 and λ5 among λ3-5 communicated on the path and λ4 and λ5 communicated on path R2 collide. Therefore, the method of switching path R3 to the path of nodes A, B, C, F, E, D and assigning wavelengths based on Rule 2 does not satisfy Rule 1. Therefore, path R3 cannot be switched. As a result, in the optical mesh network, λ3-5 is not used. Therefore, this method does not maximize the number of wavelengths available in the optical network.

[0018] Therefore, hereinafter, a method of maximizing the number of wavelengths available in the optical network will be described.

[0019] Next, the hardware of the control device 100 will be described. Figure 4 is a diagram showing the hardware of the control device according to Embodiment 1. The control device 100 includes a processor 101, a volatile memory device 102, and a non-volatile memory device 103.

[0020] The processor 101 controls the entire control device 100. For example, the processor 101 is a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or the like. The processor 101 may be a multi-processor. Further, the control device 100 may have a processing circuit.

[0021] The volatile memory device 102 is the main memory device of the control device 100. For example, the volatile memory device 102 is a RAM (Random Access Memory). The non-volatile memory device 103 is the auxiliary storage device of the control device 100. For example, the non-volatile memory device 103 is an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0022] Next, the functions of the control device 100 will be described. FIG. 5 is a block diagram showing the functions of the control device according to Embodiment 1. The control device 100 includes a storage unit 110, a monitoring unit 120, and a control unit 130.

[0023] The storage unit 110 may be realized as a storage area secured in the volatile storage device 102 or the non-volatile storage device 103. Part or all of the monitoring unit 120 and the control unit 130 may be realized by a processing circuit. Also, part or all of the monitoring unit 120 and the control unit 130 may be realized as modules of a program executed by the processor 101.

[0024] The storage unit 110 stores control information 111. The control information 111 includes a first rule indicating that a path in which a failure has occurred is excluded from the paths to be switched to. The control information 111 includes a second rule indicating that when the path is switched back, wavelength allocation is performed so that wavelengths do not collide. The second rule is the same as Rule 1 in the comparative example. The control information 111 includes a third rule indicating that switching and wavelength allocation are preferentially performed for a path through which an optical signal in which a plurality of optical signals are multiplexed is communicated among a plurality of paths in the optical mesh network 200.

[0025] The monitoring unit 120 monitors the optical mesh network 200. When a failure is detected in the optical mesh network 200 by the monitoring unit 120, the control unit 130 performs path switching and allocation of a plurality of wavelengths based on the control information 111. For example, when performing path switching, the control unit 130 transmits a switching instruction to the nodes existing on the source path and the nodes existing on the destination path. Thereby, the path is switched. Also, the control unit 130 transmits an instruction to the nodes existing on the destination path so that the optical signal of the allocated wavelength can move.

[0026] Next, the processing of the control device 100 will be described using a specific example. Figures 6(A) and (B) are diagrams showing a specific example (1-1) of the process executed by the control device of Embodiment 1. The state in Figure 6(A) is the same as the state in Figure 2(A). The monitoring unit 120 detects that a failure has occurred in the paths of nodes A and D and the paths of nodes B and E. Since a failure has been detected, the control unit 130 performs path switching and assignment of a plurality of wavelengths based on the control information 111. Based on the first rule, the control unit 130 excludes the paths of nodes A and D and the paths of nodes B and E from the candidate paths for switching.

[0027] Figure 6(B) shows the state after Figure 6(A). The control unit 130 performs path switching and assignment of a plurality of wavelengths based on the third rule. Specifically, based on the third rule, the control unit 130 switches the path R3 to the path R4. The path R4 is the path of nodes A, B, C, F, E, and D. The control unit 130 assigns λ1-3 to the path R4. Also, the assignment of λ1-3 to the path R4 conforms to the second rule.

[0028] Figures 7(A) and (B) are diagrams showing a specific example (1-2) of the process executed by the control device of Embodiment 1. Figure 7(A) shows the state after Figure 6(B). The control unit 130 switches the path R1 to the path R5. The path R5 is the path of nodes A, B, C, F, E, and D. Based on the second rule, the control unit 130 assigns λ6 to the path R5.

[0029] Figure 7(B) shows the state after Figure 7(A). The control unit 130 switches the path R2 to the path R6. The path R6 is the path of nodes C and F. Based on the second rule, the control unit 130 assigns λ4 and λ5 to the path R6.

[0030] Figure 8 is a diagram showing a specific example (1-3) of the process executed by the control device of Embodiment 1. Figure 8 shows the state after Figure 7(B). Note that the state following the state of FIG. 6(B) may be the state of FIG. 7(B). The state following the state of FIG. 7(B) may be the state of FIG. 7(A). The state following the state of FIG. 7(A) may be the state of FIG. 8.

[0031] According to Embodiment 1, the control device 100 can use the maximum number of wavelengths available in the optical network by performing path switching and wavelength allocation using the control information 111.

[0032] Embodiment 2. Next, Embodiment 2 will be described. In Embodiment 2, matters different from Embodiment 1 will be mainly described. And in Embodiment 2, the description of matters common to Embodiment 1 will be omitted.

[0033] First, a comparative example will be described. FIGS. 9(A) and (B) are diagrams showing Comparative Example (2-1). FIG. 9 shows nodes A to F. The optical mesh network is constructed with nodes A to F. In the optical mesh network, it is possible to use wavelengths λ1 to 6 having a bandwidth of 50 GHz.

[0034] The paths of nodes A, B, E, and D are referred to as path R1. Nodes A, B, E, and D communicate an optical signal of λ1-3 of 150 GHz (that is, the total value of the bandwidths of three wavelengths). The optical signal of λ1-3 is a signal in which three optical signals are multiplexed. The paths of nodes C, B, E, and F are referred to as path R2. Nodes C, B, E, and F communicate an optical signal of λ5 of 50 GHz and an optical signal of λ6 of 50 GHz. The path of nodes A and D is referred to as path R3. Nodes A and D communicate an optical signal of λ1 of 50 GHz.

[0035] FIG. 9(A) shows that a failure has occurred in the paths of nodes A and D and the paths of nodes B and E. Since a failure has occurred, path switching is performed. Path switching and wavelength allocation are performed based on Rule 1 and Rule 2 described in FIG. 2. Figure 9(B) shows the state after Figure 9(A). Route R1 is switched to route R4. Route R4 is the route of nodes A, B, C, F, E, D. λ1-3 is assigned to route R4 based on Rule 1 and Rule 2.

[0036] Figures 10(A) and (B) are diagrams showing Comparative Example (2-2). Figure 10(A) shows the state after Figure 9(B). Route R2 is switched to route R5. Route R5 is the route of nodes C, F. λ4 and λ5 are assigned to route R5 based on Rule 1 and Rule 2.

[0037] Figure 10(B) shows the state after Figure 10(A). When route R3 is switched to the route of nodes A, B, C, F, E, D, λ6 is assigned to the route based on Rule 2. Here, when the obstacle is overcome, route R5 is switched to route R2. λ5 and λ6 are assigned to route R2. The λ6 communicated on this route and the λ6 communicated on route R2 collide. Therefore, the method of switching route R3 to the route of nodes A, B, C, F, E, D does not satisfy Rule 1. Therefore, the switching of route R3 cannot be performed. For this reason, in the optical mesh network, λ6 is not used. Therefore, with this method, the number of wavelengths available in the optical network is not used to the maximum.

[0038] Therefore, hereinafter, a method of using the number of wavelengths available in the optical network to the maximum will be described.

[0039] Figure 11 is a block diagram showing the functions of the control device according to Embodiment 2. The configuration of Figure 11 that is the same as the configuration shown in Figure 5 is given the same reference numerals as those shown in Figure 5. The control device 100a includes a storage unit 110a and a control unit 130a.

[0040] The storage unit 110a stores control information 111a. The control information 111a includes a first rule indicating that a route in which an obstacle has occurred is excluded from the switching destination route. When the route is switched back, the control information 111a includes a second rule indicating that wavelength allocation is performed so that wavelengths do not collide. After performing switching and wavelength allocation with priority given to the route through which the optical signal multiplexing a plurality of optical signals is communicated, the control information 111a includes a third rule indicating that switching and wavelength allocation of the route are performed in descending order of the number of nodes included in the route after switching. The control information 111a includes a fourth rule indicating that wavelength allocation is performed based on the First-Fit method. The control information 111a includes a fifth rule indicating that switching and wavelength allocation are performed with priority given to the route through which the optical signal multiplexing a plurality of optical signals is communicated among a plurality of routes in the optical mesh network 200.

[0041] When a failure is detected in the optical mesh network 200, the control unit 130a performs route switching and allocation of a plurality of wavelengths based on the control information 111a.

[0042] Next, the processing of the control device 100a will be described using a specific example. FIGS. 12(A) and (B) are diagrams showing a specific example (2-1) of the processing executed by the control device according to the second embodiment. The state in FIG. 12(A) is the same as the state in FIG. 9(A). The monitoring unit 120 detects that a failure has occurred in the routes of nodes A and D and the routes of nodes B and E. Since a failure is detected, the control unit 130a performs route switching and allocation of a plurality of wavelengths based on the control information 111a. Based on the first rule, the control unit 130a excludes the routes of nodes A and D and the routes of nodes B and E from the candidate routes for switching.

[0043] FIG. 12(B) shows the state after FIG. 12(A). The control unit 130a switches the route R1 to the route R4 based on the fifth rule. The route R4 is the route of nodes A, B, C, F, E, and D. The control unit 130a allocates λ1-3 to the route R4 based on the fourth and fifth rules. Also, the allocation of λ1-3 to the route R4 conforms to the second rule.

[0044] Figures 13(A) and (B) are diagrams showing specific examples (2-2) of the processing executed by the control device according to Embodiment 2. Figure 13(A) shows the state after Figure 12(B).

[0045] The control unit 130a switches the path and assigns wavelengths based on the second, third, and fourth rules. Specifically, since it is after the fifth rule is applied, the control unit 130a determines the order to switch the path based on the third rule. Here, when switching the path R3, the number of nodes included in the path after switching is six (i.e., the six nodes A, B, C, F, E, and D). When switching the path R2, the number of nodes included in the path after switching is two (i.e., the two nodes C and F). Therefore, the control unit 130a determines to switch the path R2 after switching the path R3. The control unit 130a switches the path R3 to the path R5. The path R5 is the path of nodes A, B, C, F, E, and D. The control unit 130a assigns λ4 to the path R5 based on the second and fourth rules.

[0046] Figure 13(B) shows the state after Figure 13(A). The control unit 130a switches the path R2 to the path R6. The path R6 is the path of nodes C and F. The control unit 130a assigns λ5 and λ6 to the path R6 based on the second and fourth rules.

[0047] Figure 14 is a diagram showing a specific example (2-3) of the processing executed by the control device according to Embodiment 2. Figure 14 shows the state after Figure 13(B).

[0048] According to Embodiment 2, the control device 100a can use the maximum number of available wavelengths in the optical network by switching the path and assigning wavelengths using the control information 111a.

[0049] Further, the control information 111a may not include the fifth rule. When the fifth rule is not included in the control information 111a, the third rule indicates that the path switching and wavelength allocation are performed in descending order of the number of nodes included in the switched path. For example, when the multiplexed optical signal does not move through the optical mesh network 200, the control device 100a performs path switching and allocation of a plurality of wavelengths using the control information 111a that does not include the fifth rule.

[0050] Furthermore, the control information 111a may indicate the following content. The control information 111a includes a first rule indicating to exclude a path where a failure has occurred from the path to be switched to. The control information 111a includes a second rule indicating to perform wavelength allocation so that wavelengths do not collide when the path is switched back. The control information 111a includes a third rule indicating to perform path switching and wavelength allocation in descending order of the evaluation value calculated based on the number of nodes included in the path after switching and the bandwidth corresponding to the path after switching. The control information 111a includes a fourth rule indicating to perform wavelength allocation based on the First-Fit method. For example, when the optical mesh network 200 is in the state of FIG. 12(A), the control unit 130a calculates an evaluation value. Specifically, the control unit 130a calculates an evaluation value of "900 (= 6 × 150)" based on the number of nodes included in the path after switching the path R1 (i.e., 6 nodes of nodes A, B, C, F, E, D) and the bandwidth corresponding to the path after switching (i.e., 150 GHz (= 50 GHz × 3)). The control unit 130a calculates an evaluation value of "100 (= 2 × 50)" based on the number of nodes included in the path after switching the path R2 (i.e., 2 nodes of nodes C, F) and the bandwidth corresponding to the path after switching (i.e., 50 GHz). The control unit 130a calculates an evaluation value of "300 (= 6 × 50)" based on the number of nodes included in the path after switching the path R3 (i.e., 6 nodes of nodes A, B, C, F, E, D) and the bandwidth corresponding to the path after switching (i.e., 50 GHz). Therefore, the control unit 130a determines to perform path switching and wavelength allocation in the order of path R1, path R3, and path R2. After that, similar to FIGS. 12(B), 13(A), and (B), path switching and wavelength allocation are executed. Therefore, the control device 100a can use the maximum number of available wavelengths in the optical network by performing path switching and wavelength allocation using the control information 111a.

[0051] Embodiment 3. Next, Embodiment 3 will be described. In Embodiment 3, matters different from Embodiment 1 will be mainly described. And in Embodiment 3, the description of matters common to Embodiment 1 will be omitted. In Embodiments 1 and 2, the case where the route is determined and switched after a failure occurs was described. In Embodiment 3, the case where the switching destination route is determined in advance will be described.

[0052] First, the case where the switching destination route is determined in advance will be described. Here, the switching destination route is called a reserved route.

[0053] FIG. 15 is a diagram showing an example of the case where the reserved route of Embodiment 3 is determined. FIG. 15 shows nodes A to I. The routes of nodes A, B, and C are route Y1. In route Y1, an optical signal of λ1 is communicated. The routes of nodes G, H, and I are route Y2. In route Y2, an optical signal of λ1 is communicated.

[0054] The routes of nodes A, D, E, F, and C are the reserved route Z1. The routes of nodes G, D, E, F, and I are the reserved route Z2. When a failure occurs in the route between node B and node C, route Y1 switches to the reserved route Z1. Here, node F has an RGN (Regenerator). The RGN can switch the wavelength. Therefore, for example, when an optical signal of λ1 is input to node F, the optical signal of λ1 switches to an optical signal of another wavelength.

[0055] Next, a comparative example of the method for determining the reserved route will be described. FIGS. 16(A) and (B) are diagrams showing Comparative Example (3). FIG. 16(A) shows nodes A to F. An optical mesh network is constructed by nodes A to F. In the optical mesh network, λ1 to 6, which are wavelengths with a bandwidth of 50 GHz, can be used.

[0056] The paths of nodes A, D, and E are referred to as path R1. Nodes A, D, and E communicate with an optical signal of λ4 at 50 GHz and an optical signal of λ5 at 50 GHz. The paths of nodes C, F, E, and D are referred to as path R2. Nodes C, F, E, and D communicate with an optical signal of λ6 at 50 GHz. The paths of nodes D, E, and F are referred to as path R3. Nodes D, E, and F communicate with optical signals of λ1-3 at 150 GHz (i.e., the total bandwidth of three wavelengths). The optical signals of λ1-3 are signals in which three optical signals are multiplexed.

[0057] In the optical mesh network, a reserved path is set. A wavelength is assigned to the reserved path. Two rules are used for setting the wavelength to be assigned to the reserved path. Rule 1 is to perform wavelength assignment so that wavelengths do not collide when the path is rolled back. Rule 2 is to perform wavelength assignment based on a wavelength assignment algorithm (i.e., the First-Fit method). Rule 3 is to perform wavelength assignment so that the wavelengths assigned to the reserved paths do not overlap.

[0058] Figure 16(B) shows the setting of the reserved path. As the reserved path of path R1, path R4 is set. Path R4 (reserved path) is the path of nodes A, B, and E. Based on Rules 1 and 2, λ1 and λ2 are assigned to path R4 (reserved path). As the reserved path of path R2, path R5 is set. Path R5 (reserved path) is the path of nodes D, A, B, and C. Based on Rules 1 and 2, λ3 is assigned to path R5 (reserved path).

[0059] As the reserved path of path R3, path R6 is set. Path R6 (reserved path) is the path of nodes D, A, B, C, F. Here, based on Rule 2, when λ4~6 are assigned to path R6 (reserved path), λ4 and λ5 of path R6 (reserved path) collide with λ4 and λ5 of path R1. That is, when a failure occurs and path R3 switches to path R6 (reserved path), λ4 and λ5 of path R6 (reserved path) collide with λ4 and λ5 of path R1. Therefore, RGNs are installed at nodes A and C. When λ1-3 are assigned to the paths of nodes A, D and the paths of nodes C, F, the paths of nodes A, B, C switch to λ4-6. Thereby, the collision between λ4 and λ5 of path R6 (reserved path) and λ4 and λ5 of path R1 is avoided. On the other hand, when a failure occurs, λ3 of path R5 (reserved path) collides with λ3 of path R6 (reserved path). That is, a collision occurs in the path of nodes A, D. This violates Rule 3. In this way, in the optical mesh network, unusable wavelengths appear. Therefore, with this method, the maximum number of available wavelengths in the optical network cannot be fully utilized.

[0060] Therefore, hereinafter, a method of maximizing the number of available wavelengths in the optical network will be described.

[0061] FIG. 17 is a block diagram showing the functions of the control device according to Embodiment 3. The same configuration as that shown in FIG. 17 as the configuration shown in FIG. 5 is denoted by the same reference numerals as those shown in FIG. 5. The control device 100b has a storage unit 110b and a control unit 130b. The storage unit 110b stores control information 111b.

[0062] The control information 111b includes a first rule indicating that when the path is switched back, wavelength allocation is performed so that wavelengths do not collide. The control information 111b includes a second rule indicating that, among a plurality of paths in the optical mesh network 200, the path through which an optical signal in which a plurality of optical signals are multiplexed is communicated is prioritized, and the reserved path of the path and the wavelength assigned to the reserved path are set.

[0063] Before a failure occurs in the optical mesh network 200, the control unit 130b sets a reserved path, which is the path switching destination, and a wavelength to be assigned to the reserved path based on the control information 111b.

[0064] Next, the processing of the control device 100b will be described using a specific example. FIGS. 18(A) and (B) are diagrams showing a specific example (3) of the processing executed by the control device according to Embodiment 3. The state in FIG. 18(A) is the same as the state in FIG. 16(A). The control unit 130b sets a reserved path based on the second rule. Specifically, the control unit 130b sets path R4 as the reserved path for path R3 based on the second rule. Path R4 (reserved path) is the path of nodes D, A, B, C, F. The control unit 130b assigns λ1-3 to path R4 (reserved path) based on the first rule. Note that RGNs are not installed at nodes A and C.

[0065] The control unit 130b sets path R5 as the reserved path for path R2. Path R5 (reserved path) is the path of nodes D, A, B, C. The control unit 130b assigns λ6 to path R5 (reserved path) based on the first rule. The control unit 130b sets path R6 as the reserved path for path R1. Path R6 (reserved path) is the path of nodes A, B, E. The control unit 130b assigns λ4 and λ5 to path R6 (reserved path) based on the first rule.

[0066] According to Embodiment 3, the control device 100b sets a reserved path and a wavelength to be assigned to the reserved path using the control information 111b. Thereby, when a failure occurs, in the optical network, the maximum number of wavelengths available in the optical network is used. Also, no RGN is installed in the nodes. Therefore, the cost of the nodes is suppressed.

[0067] The features in each of the embodiments described above can be combined with each other as appropriate.

Explanation of Reference Numerals

[0068] 10 data centers, 20 SDH rings, 100, 100a, 100b control devices, 101 processors, 102 volatile memory devices, 103 non-volatile memory devices, 110, 110a, 110b memory units, 111, 111a, 111b control information, 120 monitoring units, 130, 130a, 130b control units, 200 optical mesh networks, R1 route, R2 route, R3 route, R4 route, R5 route, R6 route, X1 route, X2 route, Y1 route, Y2 route, Z1 reserved route, Z2 reserved route.

Claims

A control device for switching a route by controlling an optical switch included in a plurality of nodes that construct an optical mesh network, the control device having a control unit that performs route switching and allocation of a plurality of wavelengths based on control information. When a failure is detected in the optical mesh network, the control unit excludes the route where the failure has occurred from the candidate routes for switching, when a route rollback is performed, performs wavelength allocation so that wavelengths do not collide, gives priority to switching and wavelength allocation for a route through which an optical signal multiplexing a plurality of optical signals is communicated among a plurality of routes in the optical mesh network, or performs switching and wavelength allocation in descending order of the number of nodes included in the route after switching, performs wavelength allocation based on the First-Fit method, or performs switching and wavelength allocation in descending order of an evaluation value calculated based on the number of nodes included in the route after switching and the bandwidth corresponding to the route after switching, and performs wavelength allocation based on the First-Fit method as the control information. Alternatively, before a failure occurs in the optical mesh network, the control unit when a route rollback is performed, performs wavelength allocation so that wavelengths do not collide, sets a reserved route for a route through which an optical signal multiplexing a plurality of optical signals is communicated and a wavelength to be allocated to the reserved route, giving priority to the route through which the multiplexed optical signal is communicated among a plurality of routes in the optical mesh network, as the control information. Control device.

2. A control device for switching a route by controlling an optical switch included in a plurality of nodes that construct an optical mesh network, having a control unit that performs route switching and allocation of a plurality of wavelengths based on control information when a failure is detected in the optical mesh network ; The control unit uses, as the control information, a first rule indicating that a route where a failure has occurred is excluded from candidate routes for switching, a second rule indicating that when a route rollback is performed, wavelength allocation is performed so that wavelengths do not collide, and a third rule indicating that switching and wavelength allocation are preferentially performed for a route through which an optical signal multiplexing a plurality of optical signals is communicated among a plurality of routes in the optical mesh network. Control device.

3. A control device for switching a route by controlling an optical switch included in a plurality of nodes that construct an optical mesh network, When a failure is detected in the optical mesh network, a control unit that performs path switching and allocation of a plurality of wavelengths based on control information having The control unit The first rule indicating that the path where the failure has occurred is excluded from the switching destination path, the second rule indicating that when the path is switched back, the wavelengths are allocated so as not to collide, the third rule indicating that path switching and wavelength allocation are performed in descending order of the number of nodes included in the switched path, and the fourth rule indicating that wavelength allocation is performed based on the First-Fit method are used as the control information Control device

4. The control unit Among the plurality of paths in the optical mesh network, a fifth rule indicating that switching and wavelength allocation are preferentially performed for the path through which the optical signal multiplexing a plurality of optical signals is communicated is further used as the control information After preferentially performing switching and wavelength allocation for the path through which the optical signal multiplexing a plurality of optical signals is communicated, the third rule indicating that path switching and wavelength allocation are performed in descending order of the number of nodes included in the switched path is used as the control information The control device according to claim 1 or 3

5. A control device that switches a path by controlling an optical switch included in a plurality of nodes that construct an optical mesh network, When a failure is detected in the optical mesh network, a control unit that performs path switching and allocation of a plurality of wavelengths based on control information having The control unit The first rule indicating that the path where the failure has occurred is excluded from the switching destination path, the second rule indicating that when the path is switched back, the wavelengths are allocated so as not to collide, the third rule indicating that path switching and wavelength allocation are performed in descending order of the evaluation value calculated based on the number of nodes included in the switched path and the bandwidth corresponding to the switched path, and the fourth rule indicating that wavelength allocation is performed based on the First-Fit method are used as the control information Control device

6. A control device that switches a path by controlling an optical switch included in a plurality of nodes that construct an optical mesh network, Before a failure occurs in the optical mesh network, a control unit that sets a reserved path that is a path switching destination and a wavelength to be allocated to the reserved path based on control information having The control unit When a path is reverted, a first rule indicating that wavelength allocation is performed so that wavelengths do not collide, and among a plurality of paths in the optical mesh network, a path through which an optical signal in which a plurality of optical signals are multiplexed is communicated is prioritized, and a second rule indicating that the reserved path of the path through which the multiplexed optical signal is communicated and the wavelength to be allocated to the reserved path are set is used as the control information. Control device. **Claim 7**: A program that causes a processor to function as the control device according to any one of claims 1 to 6.

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