Route search device, route search method and program

Abstract

The present invention provides a route search device (1) which is for an optical path of an optical transmission network and which comprises: an optimal candidate route number derivation unit (2) that derives the number of candidate routes for which route searching is performed, on the basis of information of a topology parameter DB (42) of an optical transmission network; and an optical path design unit (3) that determines candidate routes of the number of candidate routes derived by the optimal candidate route number derivation unit, that sets a usage route to be the route among the determined candidate routes which has the smallest maximum used wavelength number in wavelength division multiplexing, and that assigns the maximum used wavelength number thereof to an optical path to be set. Specifically, on the basis of a number (422) of links , an average degree (423), the maximum (427) value of betweenness centrality, and the average (428) value of betweenness centrality, which are the information of the topology parameter DB (42), the number of candidate routes is derived by dividing the number of links by the average degree, multiplying the number of links by the maximum value of the betweenness centrality, or multiplying the number of links by the average degree and the average value of the betweenness centrality.

Description

[Technical Field]

[0001] The present invention relates to a route search device, a route search method, and a program in an optical transmission network. [Background technology]

[0002] In recent years, Internet traffic has been increasing, and there is a demand not only for faster and larger capacity optical transmission networks, but also for more efficient use of optical transmission networks. In optical transmission networks, communication data is handled by light, and the communication demands that exist within an optical transmission network are called lightpaths. In order to improve the accommodation efficiency of these lightpaths, wavelength allocation methods and route calculation methods for lightpaths are being studied.

[0003] A conventional route calculation method is disclosed in Non-Patent Document 1. In Non-Patent Document 1, by selecting a route with a small maximum usable wavelength number when designing an optical path, wavelength utilization efficiency is improved by reducing the maximum usable wavelength number. Specifically, multiple candidate routes are determined, and after searching for available wavelengths for each candidate route, the candidate route with the smallest maximum usable wavelength number is adopted as the route to be used. Note that in this specification, the maximum usable wavelength number is the largest wavelength number among the wavelengths corresponding to the wavelengths of the wavelength-multiplexed optical signal on the route. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Yokoi, Hanami, Koshiji, Yasuharu Kaneko, Tatsuya Matsukawa, Takashi Miyamura, "Study on Optical Path Design Method Considering Transmission Quality and Modulation," IEICE Technical Report, November 2021, Vol. 121, No. 262, NS2021-87, pp. 18-23 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technology of Non-Patent Document 1, by distributing the routes used by optical paths, it is possible to reduce bias in wavelength utilization rates of each link and improve the wavelength utilization rate of the entire optical transmission network. However, depending on the number of candidate routes, the following problems may arise.

[0006] 1 is a diagram showing the relationship between the number of candidate routes K and the maximum usable wavelength number selected by optical path design (solid line), and the relationship between the number of candidate routes K and the execution time per path of optical path design (dashed line) in an example of an optical transmission network. As shown in Fig. 1, when the number of candidate routes K is set to 2, the effect of optical path design is not fully exerted, and when the number of candidate routes K is set to 20, a problem occurs in which the execution time per path of optical path design becomes long.

[0007] In the example of FIG. 1, in order to optimize the maximum usable wavelength number for the execution time of the lightpath design, it is desirable to set the number of candidate routes to 5 or a value close to that value when designing the lightpath.

[0008] An object of the present invention is to provide a route search device that can maximize the effectiveness of optical path design and reduce execution time when searching for a route using an optical path design method that uses multiple candidate routes. [Means for solving the problem]

[0009] In order to solve the above problems, the optical path route search device of the present invention is Using the topology information, topology parameters that are necessary for determining the number of route candidates and are defined based on graph theory are derived and stored in a topology parameter DB; The system is provided with an optimum candidate route number derivation unit that derives the number of candidate routes for route search based on information from the topology parameter DB, and an optical path design unit that determines the number of candidate routes equal to the number of candidate routes derived by the optimum candidate route number derivation unit, selects the route with the smallest maximum usable wavelength number in wavelength multiplexing division among the determined candidate routes as the usable route, and assigns this maximum usable wavelength number to the optical path to be set. [Effects of the Invention]

[0010] According to the present invention, when a route search device searches for a route by an optical path design method using a plurality of candidate routes, it is possible to maximize the effect of the optical path design and reduce the execution time. [Brief explanation of the drawings]

[0011] [Figure 1] 10A and 10B are diagrams illustrating the relationship between the number of candidate routes and the maximum usable wavelength number selected by optical path design, and the relationship between the number of candidate routes and the execution time of optical path design. [Figure 2] 1 is a diagram illustrating a configuration of a route search device according to an embodiment. [Figure 3] FIG. 2 is a hardware configuration diagram illustrating an example of a computer that realizes the functions of the route search device according to the embodiment. [Figure 4] FIG. 3 is a flowchart illustrating the operation of the route search device according to the embodiment. [Figure 5] FIG. 1 illustrates an example of an optical transmission network that performs route discovery for an optical path. [Figure 6] FIG. 10 is a diagram illustrating an example of the configuration of a topology information DB. [Figure 7] FIG. 10 is a diagram illustrating the configuration of a topology parameter DB. [Figure 8] FIG. 1 is a diagram illustrating a state of an optical transmission network when an optical path is set up. [Figure 9A] FIG. 10 is a diagram showing a first candidate route. [Figure 9B] FIG. 10 is a diagram showing a second candidate route. [Figure 9C] FIG. 10 is a diagram showing a third candidate route. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a method for deriving the number of optimal candidate routes in a route search and a route search device according to an embodiment will be described in detail with reference to the drawings. FIG. 2 is a diagram showing the configuration of a route search device 1 according to an embodiment that determines the routes and wavelength allocations of optical paths in an optical transmission network 7. As shown in FIG.

[0013] In detail, the optical transmission network 7 is a backbone network such as an IP communication network that realizes communication using optical signals, and connects nodes (hereinafter referred to as links) using optical fibers that transmit wavelength-multiplexed optical signals, and forms an optical path network using optical paths set up through one or more nodes.

[0014] The route search device 1 of the embodiment has an optical path design unit 3 that determines the optimal optical path route and wavelength allocation using the technology described in non-patent document 1, and an optimal candidate route number derivation unit 2 that uses the optical path design unit 3 to derive the number of candidate routes, and controls the nodes using a node control device (not shown) to set optical paths in the optical transmission network 7. The optimum candidate route number derivation unit 2 comprises a topology parameter derivation unit 21, the details of which will be described later, and a candidate route number calculation unit 22.

[0015] The route search device 1 of the embodiment also has a storage unit 4 including a topology information DB 41 that stores topology information including information indicating the connection relationships between nodes and links in the optical transmission network and distances between nodes, and a topology parameter DB 42 that stores parameters used to derive the number of optimal candidate routes derived by the topology parameter derivation unit 21. The configurations of the topology information DB 41 and the topology parameter DB 42 will be described later.

[0016] Furthermore, the route search device 1 of the embodiment has an input unit 5 for inputting topology information used in optical path design, and an output unit 6 for outputting execution results of various functions, etc.

[0017] Specifically, the route search device 1 of the embodiment is realized by a computer 300 having a configuration as shown in FIG. 3 is a hardware configuration diagram showing an example of a computer 300 that realizes the functions of the route search device 1 of the embodiment. The computer 300 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM 303, an HDD (Hard Disk Drive) 304, an input / output I / F (Interface) 305, a communication I / F 306, and a media I / F 307.

[0018] The CPU 301 operates based on a program stored in the ROM 302 or the HDD 304, and performs control by the control unit. The ROM 302 stores a boot program executed by the CPU 301 when the computer 300 is started up, programs related to the hardware of the computer 300, and the like.

[0019] The CPU 301 controls an input device 310 such as a mouse or keyboard, and an output device 311 such as a display or printer, via an input / output I / F 305. The CPU 301 acquires data from the input device 310 via the input / output I / F 305, and outputs generated data to the output device 311. Note that a GPU (Graphics Processing Unit) or the like may be used as a processor together with the CPU 301.

[0020] The HDD 304 stores programs executed by the CPU 301 and data used by the programs. The communication I / F 306 receives data from other devices via a communication network (e.g., NW (Network) 320) and outputs the data to the CPU 301, and also transmits data generated by the CPU 301 to other devices via the communication network.

[0021] Media I / F 307 reads a program or data stored in recording medium 312 and outputs it to CPU 301 via RAM 303. CPU 301 loads a program related to a target process from recording medium 312 onto RAM 303 via media I / F 307, and executes the loaded program. Recording medium 312 is an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase Change Rewritable Disc), a magneto-optical recording medium such as an MO (Magneto Optical Disk), a magnetic recording medium, a semiconductor memory, or the like.

[0022] For example, when a computer 300 or the like functions as the route search device 1 of the embodiment, a CPU 301 of the computer 300 executes a program loaded on a RAM 303 to realize the functions of an optimum candidate route number derivation unit 2 and an optical path design unit 3 of the route search device 1. Furthermore, a HDD 304 functions as a storage unit 4 that stores a topology information DB 41 and a topology parameter DB 42, and the data in the RAM 303 is stored in the HDD 304.

[0023] The CPU 301 reads and executes a program related to the target processing from the recording medium 312. Alternatively, the CPU 301 may read a program related to the target processing from another device via a communication network (NW 320).

[0024] Next, the operation of the route search device 1 of the embodiment will be described with reference to the flowchart of FIG. In step S41, the topology parameter derivation unit 21 (see FIG. 2) of the optimum number of candidate routes derivation unit 2 derives parameters necessary for determining the number of candidate routes based on the information stored in the topology information DB 41, and stores them in the topology parameter DB 42.

[0025] In step S42, the number of candidate routes calculation unit 22 derives an optimum value for the number of candidate routes to be evaluated by the optical path design unit 3 based on the topology parameter DB 42 using a derivation method, the details of which will be described later.

[0026] In step S43, the optical path design unit 3 finds candidate routes equal to the number of candidate routes calculated by the candidate route number calculation unit 22 in step S42, and determines the routes and wavelengths of optical paths that improve the wavelength utilization rate of the entire optical transmission network, taking into consideration the continuity of wavelengths across multiple links in the optical transmission network 7, as in the technology of Non-Patent Document 1. Details will be described later.

[0027] In step S 44 , the route search device 1 controls a node control device (not shown) based on the route of the optical path determined by the optical path design unit 3 and the allocation of wavelengths, to set an optical path in the optical transmission network 7 .

[0028] The function of the optimum number of candidate routes derivation unit 2 (number of candidate routes calculation unit 22) will be described in more detail below. First, the configurations of the topology information DB 41 and the topology parameter DB 42 that the optimal candidate route number derivation unit 2 refers to will be described.

[0029] FIG. 5 is a diagram showing an example of an optical transmission network 7 in which the route search device 1 performs route searches for optical paths.

[0030] The black circles in Fig. 5 indicate deployed stations (hereinafter sometimes referred to as nodes), and the numbers attached to the black circles indicate the node numbers that indicate the stations. The solid lines in Fig. 5 also indicate optical fiber transmission paths (hereinafter sometimes referred to as links) between stations. The optical transmission network 7 is configured by connecting multiple nodes via links.

[0031] The route search device 1 (optical path design unit 3) designs optical paths according to traffic demand between nodes and constructs an optical path network, taking into consideration factors such as wavelength continuity across multiple links in the optical transmission network 7, constraints caused by factors that degrade optical transmission, and redundancy to increase the reliability of optical paths.

[0032] FIG. 6 is a diagram showing an example of the configuration of the topology information DB 41 that holds information indicating the connection relationships of nodes, links, etc. in the optical transmission network 7 shown in FIG.

[0033] The topology information DB 41 comprises a node A number 411 indicating the node number of the start node for each link of the optical transport network 7, a node Z number 412 indicating the node number of the end node, a link distance 413, and a link number 414 for identifying the link.

[0034] 7 is a diagram illustrating the configuration of the topology parameter DB 42 derived by the topology parameter derivation unit 21 of the optimum candidate route number derivation unit 2 as parameters necessary for determining the number of candidate routes based on information in the topology information DB 41. The topology parameters are defined for the optical transmission network 7 based on graph theory.

[0035] Specifically, the number of nodes 421 indicates the number of nodes in the optical transmission network 7 shown in Fig. 5. Note that a node is a point in graph theory. The number of links 422 indicates the number of links in the optical transport network 7 shown in FIG. The average degree 423 indicates the average value of the degree (the number of edges joining the vertices of the graph) corresponding to the number of links connected to a certain node in the optical transmission network 7.

[0036] The connectivity 424 indicates the number of nodes that need to be removed to disconnect the optical transport network 7, which is a connected graph. The average connectivity 425 indicates the average value of the connectivity 424 . Edge connectivity 426 indicates the number of links that need to be removed to disconnect optical transport network 7, which is a connected graph.

[0037] Betweenness centrality (average) 427 is the average value of betweenness centrality, which is the ratio of the shortest paths that pass through a certain node A to the shortest paths that connect two other nodes. Betweenness centrality (maximum) 428 is the maximum value of betweenness centrality, which is the ratio of the shortest paths that pass through a certain node A to the shortest paths that connect two other nodes.

[0038] Next, the processing of the number of candidate routes calculation unit 22 of the optimum number of candidate routes derivation unit 2 will be described. The candidate route number calculation unit 22 refers to the topology parameter DB 42, and the optical path design unit 3 derives the number of candidate routes using one of the following calculation formulas.

[0039] Number of candidate paths = Number of links / Average degree (1) Number of candidate paths = Number of links × Betweenness centrality (maximum) (2) Number of candidate routes = number of links × average degree × betweenness centrality (average) (3)

[0040] In addition, the candidate route number calculation unit 22 may calculate the number of candidate routes using equations (1) to (3), and the smallest value of the calculated number of candidate routes may be the number of candidate routes calculated by the candidate route number calculation unit 22.

[0041] Here, a specific calculation example of the number of candidate routes calculation unit 22 will be described. The candidate route number calculation unit 22 refers to the topology parameter DB 42 and calculates the number of candidate routes using equation (1).

[0042] Specifically, the number of links=17 and the average degree=2.83 are read from the topology parameter DB 42, and are calculated as 6.01 using equation (1), so the number of candidate routes is 6.

[0043] The optical path design unit 3 calculates routes from the start node to the end node for the number of candidate routes calculated by the candidate route number calculation unit 22 as described above, and determines the optimal optical path according to the traffic demand between nodes, taking into consideration the continuity of wavelengths across multiple links in the optical transmission network 7, constraints caused by factors that cause degradation in optical transmission, redundancy to improve the reliability of the optical path, etc.

[0044] Next, the method of determining an optical path by the optical path design unit 3 will be explained with reference to FIGS. 8, 9A, 9B, and 9C.

[0045] Figure 8 shows the state of the optical transmission network when an optical path is set up. Node S is the start node of the optical path, and node D is the end node of the optical path. Each link is an optical fiber that transmits an optical signal that has been wavelength-multiplexed into six wavelengths, and the wavelength numbers of each link indicate the used wavelengths and unused wavelengths.

[0046] Although not shown, multiple optical paths using the wavelengths used by the links have already been set in the optical transmission network of Figure 8, and the optical path design unit 3 adds (sets) an optical path from node S to node D.

[0047] If the candidate route number calculation unit 22 derives the number of candidate routes to three based on the state of the optical transmission network in Fig. 8, the optical path design unit 3 obtains three candidate routes as shown in Fig. 9A, Fig. 9B, and Fig. 9C. The optical path design unit 3 obtains the three candidate routes in order of shortest route by, for example, the K-Shortest Path algorithm.

[0048] The optical path design unit 3 selects the wavelength with wavelength number 6 as the wavelength to be used in the candidate route a in FIG. 9A, taking into consideration the continuity of wavelengths and constraints caused by factors that cause degradation of optical transmission, and determines the optical path a.

[0049] Furthermore, the optical path design unit 3 can select wavelengths with wavelength numbers 5 and 6 for candidate route b in FIG. 9B, and obtains optical path b1 with wavelength number 5 for candidate route b and optical path b2 with wavelength number 6 for candidate route b.

[0050] Furthermore, the optical path design unit 3 can select wavelengths with wavelength number 3 and wavelength number 4 for candidate route c in Fig. 9C, and obtains optical path c1 with wavelength number 3 for candidate route c and optical path c2 with wavelength number 4 for candidate route c. Note that although wavelength numbers 5 and 6 can also be used in Fig. 9C, wavelength numbers 3 and 4 will be used here.

[0051] Then, of the three candidate routes a, b, and c in Figures 9A, 9B, and 9C, the optical path design unit 3 selects candidate route c in Figure 9C, which has the smallest maximum usable wavelength number, which is the largest wavelength number corresponding to the wavelength of the wavelength-multiplexed optical signal on the route, as the route to be used, and assigns the wavelength with wavelength number 3 to the optical path to be added.

[0052] As described above, the optical path design unit 3 finds candidate routes equal to the number of candidate routes derived by the optimal candidate route number derivation unit 2, and selects the route with the smallest maximum usable wavelength number in wavelength multiplexing division from among the found candidate routes as the utilized route, and assigns this maximum usable wavelength number to the optical path that is set. This reduces bias in utilized wavelengths and increases the number of accommodated optical paths, thereby improving the wavelength utilization rate of the entire optical transmission network.

[0053] <Effects> The effects of the route search device according to the present invention will be described below. The route search device 1 according to the present invention is a route search device 1 for optical paths in an optical transmission network, and is characterized by comprising: an optimum candidate route number derivation unit 2 that derives the number of candidate routes for route search based on information from a topology parameter DB 42 of the optical transmission network; and an optical path design unit 3 that determines candidate routes equal to the number of candidate routes derived by the optimum candidate route number derivation unit 2, selects the route with the smallest maximum usable wavelength number in wavelength multiplexing division as the route to be used, and assigns this maximum usable wavelength number to the optical path to be set.

[0054] This allows the candidate routes to be searched for to be optimized, maximizing the effectiveness of lightpath design and reducing execution time.

[0055] More specifically, the optimum candidate route number derivation unit 2 calculates the number of candidate routes by dividing the number of links 422 by the average degree 423 based on the number of links 422 and the average degree 423 in the topology parameter DB 42 . Furthermore, the optimum candidate route number derivation unit 2 calculates the number of candidate routes by multiplying the number of links 422 by the maximum betweenness centrality value 428 based on the number of links 422 and the maximum betweenness centrality value 428 in the topology parameter DB 42 . In addition, the optimal candidate route number derivation unit 2 calculates the number of candidate routes based on the values ​​of the number of links 422, average degree 423, and average betweenness centrality 427 in the topology parameter DB 42 by multiplying the values ​​of the number of links 422, average degree 423, and average betweenness centrality 427.

[0056] This allows the optimum number of candidate routes derivation unit 2 to easily calculate the number of candidate routes, thereby making it possible to reduce the calculation resources used to derive the number of candidate routes.

[0057] The present invention is not limited to the above-described embodiments, and many modifications can be made by a person having ordinary skill in the art within the technical concept of the present invention. [Explanation of symbols]

[0058] 1. Route search device 2. Optimal candidate route number calculation part 21 Topology parameter derivation part 22 Candidate route number calculation unit 3 Optical Path Design Department 4 Storage section 41 Topology Information DB 42 Topology parameter DB 5 Input section 6 Output section 7 Optical Transport Network

Claims

1. An optical path route search device for an optical transmission network, comprising: an optimal candidate route number derivation unit that derives topology parameters, which are parameters necessary for determining the number of candidate routes and are defined based on graph theory, using topology information of the optical transmission network, stores the derived topology parameters in a topology parameter DB, and derives the number of candidate routes for performing a route search based on information in the topology parameter DB; an optical path design unit that determines candidate routes by the number of candidate routes derived by the optimal candidate route number derivation unit, determines the route having the smallest maximum usable wavelength number in wavelength multiplexing division among the determined candidate routes as the utilized route, and assigns the maximum usable wavelength number to the optical path to be set; Equipped with The optimal candidate route number derivation unit calculates the number of candidate routes by dividing the number of links by the average degree based on the number of links and the average degree in the topology parameter DB. A route search device characterized by:

2. An optical path route search device for an optical transmission network, comprising: an optimal candidate route number derivation unit that derives topology parameters, which are parameters necessary for determining the number of candidate routes and are defined based on graph theory, using topology information of the optical transmission network, stores the derived topology parameters in a topology parameter DB, and derives the number of candidate routes for performing a route search based on information in the topology parameter DB; an optical path design unit that determines candidate routes by the number of candidate routes derived by the optimal candidate route number derivation unit, determines the route having the smallest maximum usable wavelength number in wavelength multiplexing division among the determined candidate routes as the utilized route, and assigns the maximum usable wavelength number to the optical path to be set; Equipped with The optimal candidate route number derivation unit calculates the number of candidate routes by multiplying the number of links by the maximum value of betweenness centrality based on the number of links in the topology parameter DB and the maximum value of betweenness centrality. A route search device characterized by:

3. An optical path route search device for an optical transmission network, comprising: an optimal candidate route number derivation unit that derives topology parameters, which are parameters necessary for determining the number of candidate routes and are defined based on graph theory, using topology information of the optical transmission network, stores the derived topology parameters in a topology parameter DB, and derives the number of candidate routes for performing a route search based on information in the topology parameter DB; an optical path design unit that determines candidate routes by the number of candidate routes derived by the optimal candidate route number derivation unit, determines the route having the smallest maximum usable wavelength number in wavelength multiplexing division among the determined candidate routes as the utilized route, and assigns the maximum usable wavelength number to the optical path to be set; Equipped with The optimal candidate route number derivation unit calculates the number of candidate routes by multiplying the number of links, the average degree, and the average value of the betweenness centrality based on the number of links, the average degree, and the average value of the betweenness centrality in the topology parameter DB. A route search device characterized by:

4. A method for searching for an optical path in an optical transmission network, comprising: using topology information of the optical transmission network, deriving topology parameters that are required for determining the number of candidate routes and are defined based on graph theory, storing the parameters in a topology parameter DB, and deriving the number of candidate routes for route search based on information in the topology parameter DB; A step of obtaining candidate routes in the number equal to the number of derived candidate routes; a step of selecting a route having the smallest maximum usable wavelength number in wavelength multiplexing division from among the candidate routes found, and allocating the maximum usable wavelength number to the optical path to be set; Including, The step of deriving the number of candidate routes includes: calculating the number of candidate paths by dividing the number of links, which is the topology parameter, by the average degree, which is the topology parameter; calculating the number of candidate paths by multiplying the number of links, which is the topology parameter, by the maximum value of betweenness centrality, which is the topology parameter; or a step of calculating the number of candidate paths by multiplying the number of links, which is the topology parameter, the average degree, which is the topology parameter, and the average value of betweenness centrality, which is the topology parameter. A route search method comprising:

5. A program for causing a computer to function as the route search device according to any one of claims 1 to 3.

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