Route search device, route search method, and program

Abstract

A route search device according to one aspect of the present invention comprises a storage unit that stores resource information of a mesh network to be managed, and a processor. The processor comprises a resource management unit, an impact identification unit, and a route search unit. The resource management unit refers to the resource information and manages the mesh network in multiple layers including a physical layer and a logical layer. The impact identification unit identifies the impact of a failure that has occurred in the mesh network for each layer of the multiple layers on the basis of the resource information, and organizes, from the result of the impact identification, a network topology usable for route reconfiguration. The route search unit excludes, from the multiple layers to be managed, a route that cannot be used for the route reconfiguration in the organized network topology, generates a directed graph of the network topology of the remaining resources, and searches for possible routes using a predetermined algorithm.

Description

Route search device, route search method, and program

[0001] One aspect of the present invention relates to a route search device, a route search method, and a program.

[0002] Communication infrastructure is required to operate stably even during disasters. Mesh networks are known as a fault-tolerant network topology that can take multiple detour routes when a failure occurs.

[0003] However, in a mesh network, it is difficult to determine which route has been switched by dynamic routing. For this reason, when a failure occurs, manual work is required to identify the area affected by the failure and identify the route that has been switched to within the area that is not affected. In other words, in a mesh network, it is necessary to calculate all possible routes between the endpoints of the route you want to identify and manually determine whether there is a route that avoids the faulty area. Furthermore, from the perspective of minimizing the number of users affected by a failure, it is also necessary to calculate the number of users who will be affected by the next failure for each route found.

[0004] Patent No. 6655524 Patent No. 7107158 Patent No. 6837022

[0005] In this way, in a mesh network, if a failure occurs and a route is switched, the route must be calculated and the number of affected users (one-side outage) must be calculated. Also, if a failure occurs and no route is available, the number of affected users (two-side outage) must be calculated. In either case, a huge amount of calculation is required, and it takes a long time to get the results, which slows down the decision-making process. Furthermore, because of the urgency of the failure response, much of the calculation relies on the experience of the maintenance personnel, and there have been cases where the calculation was not accurate.

[0006] The present invention has been made in light of the above circumstances, and aims to provide a technique that can reduce the time required to calculate a route and the number of affected users.

[0007] A route search device according to one aspect of the present invention includes a memory unit that stores resource information of a mesh network to be managed, and a processor. The processor includes a resource management unit, an influence assessment unit, and a route search unit. The resource management unit manages the mesh network in multiple layers, including a physical layer and a logical layer, by referencing the resource information. The influence assessment unit assesses the influence of a failure occurring in the mesh network for each layer of the multiple layers based on the resource information, and organizes a network topology that can be used for route resetting based on the results. The route search unit excludes routes that cannot be used for route resetting in the organized network topology from the managed multilayer, converts the network topology of the remaining resources into a directed graph, and searches for possible routes using a predetermined algorithm.

[0008] According to one aspect of the present invention, it is possible to provide a technique that can reduce the time required to calculate a route and the number of affected users.

[0009] FIG. 1 is a diagram illustrating an example of a system including a route search device according to a first embodiment of the present invention. FIG. 2 is a flowchart illustrating an example of a processing procedure of the processor 11 illustrated in FIG. 1. FIG. 3 is a diagram illustrating a failure occurring in a mesh network. FIG. 4 is a diagram illustrating the processing of steps S2 and S3 in FIG. 2. FIG. 5 is a diagram illustrating the processing of identifying a section affected by the failure. FIG. 6 is a diagram illustrating the processing of step S4 in FIG. 2. FIG. 7 is a diagram illustrating the processing of step S5 in FIG. 2. FIG. 8 is a diagram illustrating the processing of steps S6 and S7 in FIG. 2. FIG. 9 is a diagram illustrating the processing of steps S6 and S7 in FIG. 2. FIG. 10 is a diagram illustrating a first example of a route search using the Dijkstra algorithm. FIG. 11 is a diagram illustrating a first example of a route search using the Dijkstra algorithm. FIG. 12 is a diagram illustrating a first example of a route search using the Dijkstra algorithm. FIG. 13 is a diagram illustrating a first example of a route search using the Dijkstra algorithm. FIG. 14 is a diagram illustrating a first example of a route search using the Dijkstra algorithm. Fig. 15 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm. Fig. 16 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm. Fig. 17 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm. Fig. 18 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm. Fig. 19 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm. Fig. 20 is a diagram for explaining a second example of a route search using the Dijkstra's algorithm.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an example of a system including a route search device according to a first embodiment of the present invention. In Fig. 1, a route search device 10 includes a processor 11, a storage 12, an interface unit 13, and a memory 14. In other words, the route search device 10 is a computer, and is realized as, for example, a personal computer or a server computer.

[0011] The interface unit 13 is connected to the network 100 and can access the database 2, for example, to acquire information such as the location of a failure. In addition, the interface unit 13 outputs the route generated by the route search device 10 and the number of affected users (calculation result 3) in response to a request from an operator at a vehicle dispatch center, for example.

[0012] The storage 12 is a non-volatile storage medium (block device) such as a hard disk drive (HDD) or a solid state drive (SSD). The storage 12 stores basic programs such as an operating system (OS) and device drivers, programs for implementing the functions of the route search device 10, and resource information 12a. The resource information 12a is information that abstracts the resources of the mesh network to be managed.

[0013] The memory 14 in FIG. 1 is, for example, a RAM (Random Access Memory), and stores a program 14 a loaded from the storage 12 as well as a calculated route 14 b calculated by the processor 11 .

[0014] The processor 11 is an arithmetic unit such as a central processing unit (CPU) or a micro processing unit (MPU), and realizes its functions by a program loaded into the memory 14 .

[0015] The processor 11 includes a resource management unit 111, an influence assessment unit 112, and a route search unit 115 as functional blocks (program modules) according to the embodiment. These functional blocks are processing functions that are realized by the processor 11 executing instructions included in the program 14a. In other words, the route search device 10 of the present invention can also be realized by a computer and a program. The program can be recorded on a recording medium such as optical media and distributed. Alternatively, the program can be provided via a network.

[0016] The resource management unit 111 manages the mesh network to be managed in multiple layers, including a physical layer and a logical layer, by referring to the resource information 12a. The influence assessment unit 112 assesses the influence of a failure that occurs in the mesh network for each layer of the multiple layers based on the resource information 12a, and from the results, organizes a network topology that can be used for reconfiguring routes.

[0017] The route search unit 115 excludes from the managed multi-layer any routes that cannot be used for route resetting in the network topology organized by the influence understanding unit 112. Then, the route search unit 115 creates a directed graph of the network topology of the remaining resources and searches for possible routes using a predetermined algorithm.

[0018] In particular, the route search unit 115 switches the algorithm for route search depending on the routing protocol used in the mesh network. For example, in a mesh network that uses Open Shortest Path First (OSPF) as the routing protocol, the route search unit 115 searches for a route using the Dijkstra algorithm.

[0019] Fig. 2 is a flowchart showing an example of a processing procedure of the processor 11 shown in Fig. 1. In the embodiment, when the occurrence of a failure is detected (step S1), the processor 11 grasps the impact of the failure for each layer of the network (step S2), and, based on the results, organizes a network topology that can be used for re-routing (step S3).

[0020] Next, the processor 11 excludes the unavailable routes from the multi-layer management (step S4), and then creates a directed graph of the network topology consisting of the remaining resources (step S5). Next, the processor 11 sets one of the vertices of this directed graph as the start (s) and one of the other vertices as the goal (g), and searches for possible routes between the start and the goal using a predetermined algorithm (step S6).

[0021] Here, the processor 11 switches the algorithm depending on the routing protocol used in the target mesh network. In this embodiment, it is assumed that OSPF (Open Shortest Path First) is used as the routing protocol, and the Dijkstra algorithm is applied as the corresponding algorithm. Pseudocode for the Dijkstra algorithm, with the start (s) as the starting point and the goal (g) as the end point, is shown in Equation 1.

[0022] Next, based on the result of step S6, if route calculation is possible, the processor 11 calculates the affected users as if one system was interrupted. If route calculation is not possible, the processor 11 calculates the affected users as if both systems were interrupted (step S7).

[0023] As shown in FIG. 3, when a failure (indicated by an x ​​in the figure) occurs in the mesh network, the route used up to that point from node X to node Y is cut off, affecting the section indicated by the two-dot chain line in FIG.

[0024] FIG. 5 is a diagram illustrating the process of identifying a section affected by a failure. Multi-layer management allows a network to be abstracted and managed into multiple layers, such as the transmission layer (physical layer), the Ether layer (logical layer), and the IP layer (logical layer). The communication characteristics of each layer (IP characteristics, Ether characteristics, transmission characteristics) can be managed independently. As shown in FIG. 5 , for example, in a network connecting multiple bases (buildings) with cables, if one of the communication devices in a building fails, the impact extends to all of the transmission layer, the Ether layer, and the IP layer.

[0025] Fig. 6 is a diagram for explaining the processing of step S4 in Fig. 2. Routes that have become unusable due to a failure are excluded from multi-layer management, and the topology consisting of the remaining routes is converted into a directed graph, resulting in the graph shown in Fig. 7. In Fig. 7, each vertex is indicated by a number, and the direction of the arrows between the vertices corresponds to the direction of communication. The numbers associated with the arrows indicate the average available bandwidth of the links connecting the vertices.

[0026] 8 and 9 are diagrams for explaining the processing of steps S6 and S7 in FIG. 2. FIG. 8 shows a route when the start is vertex (1) and the goal is (8). That is, the thick solid arrows are available switching routes. Based on this route, the number of users affected in the next failure can be estimated to be, for example, XX people.

[0027] Figure 9 shows a route when the start point is vertex (8) and the goal point is (1). In other words, the dashed arrow indicates a possible switching route. Based on this route, the number of users affected by the next failure can be estimated to be, for example, ZZ people.

[0028] Next, we will explain route search using Dijkstra's algorithm using two examples. Figures 10 to 14 show the first example, and we will use these figures to explain the case of searching for a route from vertex X to vertex Y.

[0029] (First Example) From Fig. 10, a route from vertex (1) to (3) is searched for using Dijkstra's algorithm. Next, a route from vertex (3) to (4) is searched for using Dijkstra's algorithm (Fig. 11). Next, a route from vertex (4) to (6) is searched for using Dijkstra's algorithm (Fig. 12). Next, a route from vertex (6) to (7) is searched for using Dijkstra's algorithm (Fig. 13). Finally, a route from vertex (7) to (8) is searched for using Dijkstra's algorithm (Fig. 14).

[0030] 15 to 20 are diagrams showing a first example, and a case where a route from vertex X to vertex Y is searched for will be described with reference to these diagrams.

[0031] (Second Example) From Fig. 15, a route from vertex (8) to (7) is searched for using Dijkstra's algorithm. Next, a route from vertex (7) to (4) is searched for using Dijkstra's algorithm (Fig. 16). Next, a route from vertex (4) to (6) is searched for using Dijkstra's algorithm (Fig. 17). Next, a route from vertex (6) to (7) is searched for using Dijkstra's algorithm (Fig. 18). Next, a route from vertex (7) to (2) is searched for using Dijkstra's algorithm (Fig. 19). Finally, a route from vertex (2) to (1) is searched for using Dijkstra's algorithm (Fig. 20).

[0032] As described above, in this embodiment, when a failure occurs in a mesh network, the impact of the failure is assessed for each layer, and a usable topology is organized based on the results. Unusable routes are excluded from multi-layer management, and the topology formed by the remaining resources is converted into a directed graph. Then, the start (s) and goal (g) of the communication route are determined, and whether a bidirectional route (s ⇔ g) is possible between (s) and (g) is calculated using Dijkstra's algorithm. The results are then used to calculate the route / number of affected users. This configuration makes it possible to automatically calculate the number of users affected by the failure. This reduces the time required to calculate an alternative route, allowing maintenance personnel to focus solely on verifying the results, thereby encouraging them to make the right decisions.

[0033] With existing technology, when a failure occurs in a mesh network, it is necessary to calculate all possible routes for the desired route (X⇔Y) and determine whether there is a route that avoids the failure point. Calculating the existence of a route requires manually determining whether there is a route that connects the endpoints (X⇔Y) from the countless routes, and if there is a route, the number of users who will be affected by the next failure is calculated.

[0034] In this way, all routes are calculated manually, which takes time, and because of the urgency of responding to failures, much of it relies on the experience of the maintenance staff, and there are cases where the correct results are not obtained.

[0035] In contrast, according to the embodiment, all routes can be automatically calculated using an algorithm, which reduces calculation time. Also, maintenance personnel only need to focus on checking the results, which allows them to make correct decisions.

[0036] For these reasons, according to the embodiment, it is possible to provide a technology that can shorten the time required to calculate routes and the number of affected users. As a result, it is possible to quickly propose deployment routes for emergency vehicles (such as power supply vehicles) in the event of a disaster, contributing to reducing operations. Furthermore, it is also possible to contribute to strengthening BCPs (Business Continuity Plans).

[0037] It should be noted that the present invention is not limited to the above-described embodiments, and that the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0038] 2: Database 10: Route search device 11: Processor 12: Storage 12a: Resource information 13: Interface unit 14: Memory 14a: Program 14b: Calculated route 100: Network 111: Resource management unit 112: Impact understanding unit 115: Route search unit.

Claims

1. A route search device comprising: a memory unit that stores resource information of a mesh network to be managed; and a processor, wherein the processor comprises: a resource management unit that refers to the resource information and manages the mesh network in multiple layers including a physical layer and a logical layer; an impact understanding unit that understands the impact of a failure that has occurred in the mesh network for each layer of the multiple layers based on the resource information and, from the results, organizes a network topology that can be used for route resetting; and a route search unit that excludes routes that cannot be used for route resetting in the organized network topology from the managed multi-layer, converts the network topology of the remaining resources into a directed graph, and searches for possible routes using a predetermined algorithm.

2. The route search device according to claim 1, wherein the route search unit switches algorithms depending on the routing protocol used in the mesh network.

3. The route search device according to claim 2, wherein when the routing protocol is OSPF (Open Shortest Path First), the route search unit searches for the route using Dijkstra's algorithm.

4. A route search method by a computer having a memory unit that stores resource information of a mesh network to be managed and a processor, the route search method comprising the steps of: the processor managing the mesh network at multiple layers including a physical layer and a logical layer by referring to the resource information; the processor grasping the impact of a failure that has occurred in the mesh network for each layer of the multiple layers based on the resource information; the processor organizing a network topology that can be used for route resetting from the grasped results; the processor excluding routes that cannot be used for route resetting in the organized network topology from the managed multi-layer; and the processor converting the network topology of the remaining resources into a directed graph and searching for possible routes using a predetermined algorithm.

5. A program that causes a computer to function as each of the components of the route search device according to any one of claims 1 to 3.

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