JP4175332B2 - Optimal optical path search device and optimal optical path search method - Google Patents

Description

  The present invention relates to an optimal optical path search device and an optimal optical path search method for searching for an optimal optical path arrangement in a wavelength division multiplexing optical network.

  In recent years, communication demand has been rapidly increasing due to the spread of the Internet and the like. Correspondingly, a high-speed and large-capacity optical communication network using an optical fiber or the like is being developed. In such an optical communication network, a wavelength division multiplexing (WDM) method is indispensable. Wavelength division multiplexing (WDM) is a technique for multiplexing carrier waves having different optical wavelengths. By using WDM, a plurality of carrier waves can be propagated in parallel on one optical transmission line, so that a large-capacity communication network can be constructed at low cost.

  An optical communication network using this WDM method is configured to include a plurality of nodes including routers and paths (paths) connecting nodes configured by optical fibers. In this optical network, nodes having an optical add / drop function (OADM), an optical cross connect function (OXC), and the like are used. The optical add / drop function is a function of inserting an optical carrier wave of another wavelength into an optical carrier wave multiplexed using WDM, or branching an optical carrier wave of a specific wavelength from the multiplexed optical carrier wave. The optical cross-connect function is a function for switching the propagation path of an optical carrier wave multiplexed using WDM on a wavelength basis. By using these functions, it is possible to construct an optical path arrangement (logical topology) composed of a plurality of optical paths on an optical communication network (that is, physical topology) constructed by optical transmission paths.

  When a situation that hinders communication such as failure or congestion occurs in an optical fiber as an optical communication network using WDM, by dynamically changing the optical path arrangement, avoiding the situation that hinders communication, the communication state is changed. A recovery method has been proposed. The optical path arrangement can be changed by bypassing a failure or congestion interval (hereinafter simply referred to as a failure interval) or by cutting through a node where congestion has occurred. Here, the cut-through means that the communication packet is passed through the node as it is without using the routing function of the node, that is, using only OADM or OXC (for example, Patent Documents). 1). By setting a cut-through path for a node where congestion has occurred, the processing load on the node can be reduced.

As a method for dynamically changing an optical path to bypass a faulty section, a dedicated protection method and a shared protection method are known. The exclusive protection method is a method in which one optical path is substituted with another optical path. The shared protection method is a method of substituting a plurality of optical paths with another optical path.
JP 2003-218912 A

  However, the above-described conventional method is merely a method for recovering the communication state by bypassing the failure section, and the optical path arrangement after the detour is not necessarily the optimum optical path arrangement. According to this prior art, when traffic is concentrated on a specific node, the processing load of the node can be reduced by newly setting an optical path that cuts through the node. This is because such a path setting for cutting through the node may increase the processing load of other nodes.

  Further, according to this conventional technique, when the setting of the optical path is changed, the routing information of the IP (Internet protocol) layer is changed in the optical communication network. Therefore, when a new cut-through path is set, it is determined that the cut-through path is the optimum route, and traffic may concentrate on the cut-through path. In such a case, the processing load of the cut-through node does not become excessive, but the processing load increases at the node that terminates the cut-through path.

  For this reason, when a new cut-through path is set, it is desired that traffic concentration does not occur in the entire optical communication network in consideration of a route change in the IP layer.

  However, the number of setting patterns of the optical path arrangement in the entire optical communication network increases exponentially as the number of wavelengths and the number of nodes used in the optical communication network increase. For this reason, if it is attempted to select an optimal cut-through path by predicting the traffic generation status of the entire optical communication network for all setting patterns, the processing load becomes enormous and is not realistic.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optimal optical path search apparatus and an optimal optical path search method that can efficiently search for an optimal optical path arrangement. There is to do.

In order to achieve the above-described object, an optimum optical path search apparatus according to the present invention provides an optical path in an optical network including a plurality of nodes and an optical fiber that connects adjacent nodes and transmits a wavelength multiplexed optical signal. And a traffic monitoring unit, an initialization unit, a minimum optical path selection unit, a connectivity determination unit, an optical path change unit, an interface number determination unit, and an optical path arrangement change unit. Yes.

The traffic monitoring means generates a traffic matrix based on traffic information obtained from a plurality of nodes. The initialization unit virtually sets an initial optical path for all node combinations. The minimum optical path selection means selects an optical path with the minimum traffic as the minimum optical path among the initial optical paths. The connectivity determination unit determines whether or not the minimum optical path selected by the minimum optical path selection unit can be canceled. The optical path changing means changes the minimum optical path to a non-cancellation optical path when the minimum optical path cannot be canceled, and on the other hand, if the minimum optical path can be canceled, the minimum optical path is canceled. And the traffic on the release optical path is saved. The interface number determining means determines whether the number of interfaces used in each node satisfies the usable interface number condition. The optical path arrangement changing means performs a transition process from the currently set optical path arrangement to the optimum optical path arrangement.

  Also, the optimum optical path search method according to the present invention provides traffic information obtained from a plurality of nodes in an optical network comprising a plurality of nodes and an optical fiber that connects adjacent nodes and transmits a wavelength multiplexed optical signal. The optical path is searched based on the traffic matrix generated based on the above, and includes the following processes.

First, in the initialization process, initial optical paths are set for virtually all combinations of nodes. Next, in the minimum optical path selection process, the optical path with the minimum traffic is selected as the minimum optical path among the initial optical paths. Next, in the connectivity determination process, it is determined whether or not the minimum optical path can be canceled. Next, in the optical path change process, if the minimum optical path cannot be canceled as a result of the determination in the connectivity determination process, the minimum optical path is changed to a non-released optical path, while the minimum optical path is released. If possible, the minimum optical path is changed to a cancellation optical path, and the traffic on the cancellation optical path is saved. Next, in the interface number determination process, it is determined whether the number of interfaces used in each node satisfies the usable interface number condition. Until interface number satisfying the minimum light path selection process described above, connectivity determination process, after Tsu rows repeated optical path change process and interface number determination process, the optimal optical path arrangement from an optical path arrangement that is currently set It intends line the migration process of.

  According to the optimum optical path searching apparatus and the optimum optical path searching method of the present invention, the initial optical paths are virtually set for all combinations of nodes, and the initial optical paths are arranged in ascending order of traffic while maintaining packet reachability. Is canceled, so that the optimum optical path arrangement can be obtained efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the configuration and the arrangement relationship are merely schematically shown to the extent that the present invention can be understood. In the following, preferred configuration examples of the present invention will be described. However, the numerical conditions of each component are merely preferred examples, and the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic configuration diagram for explaining an internal network that searches for an optimum optical path arrangement according to the present invention. The internal network includes a plurality of nodes (hereinafter also referred to as N) arranged in a grid, an optical fiber that connects adjacent nodes and transmits a wavelength multiplexed optical signal, and each of the plurality of nodes. A grating-type wavelength division multiplexing optical network including a management device connected to the network.

  Here, the internal network will be described assuming that nine nodes are arranged in a 3 × 3 grid. Each of these nodes is assigned a unique node ID. Here, the node ID is a natural number from 1 to 9. For example, N1 indicates a node whose node ID is 1.

  Although the details of the configuration of each node (N1 to N9) will be described later, each node includes a router connected to an external network and an optical path switching unit that determines a transmission path of an optical signal.

  Adjacent nodes are physically connected by optical fibers. Each of these optical fibers is assigned a unique fiber ID. Here, the fiber ID is a natural number from 1 to 12. An optical fiber is represented by F, for example, F1 represents an optical fiber having a fiber ID of 1. The optical fibers F1 to F12 can communicate bidirectionally between adjacent nodes and can transmit a wavelength-multiplexed optical signal obtained by multiplexing a plurality of optical signals having different wavelengths by wavelength multiplexing. In addition, it is good also as a structure which carries out bidirectional | two-way wavelength division multiplexing optical communication by making the optical fiber which connects between nodes one by one, and has the structure which comprises two optical fibers and performs one-way wavelength division multiplexing optical communication. good. The optical fiber can have any suitable configuration depending on settings such as the wavelength used. Here, the internal network has been described as a lattice-type wavelength division multiplexing optical network in which nine nodes are arranged in a lattice pattern, but the number of nodes and the network configuration are not limited to this example.

  FIG. 2 is a schematic configuration diagram for explaining a control network for controlling the path arrangement of the internal network described with reference to FIG.

  The control network includes nodes (N1 to N9), a management device 270, and a control line 250 that transmits and receives control signals between the management device 270 and each node (N1 to N9). The control line 250 includes a setting line 251 and a measurement line 253. The setting signal generated by the management device 270 is sent to N1 to N9 via the setting line 251. The traffic measurement results at N1 to N9 are sent to the management apparatus 270 via the measurement line 253.

  FIG. 3 is a schematic configuration diagram for explaining the configuration of the node (N).

  The nodes are first to fourth input optical fibers 301a to 301d, first to fourth demultiplexers 321a to 321d, an optical path switching unit 330, first to fourth multiplexers 326a to 326d, and first to fourth outputs. Optical fibers 306a to 306d, a router 350, first to fourth conversion devices 353a to 353d, and a control device 335 are provided. The optical path switching unit 330 includes a termination unit 331 and an optical switch unit 333.

  An optical signal wavelength-multiplexed from another node is input to the node via input optical fibers 301a to 301d. Here, the optical signal is described as a wavelength multiplexed signal obtained by multiplexing four types of wavelengths, but is not limited to four types. Each of these four types of wavelengths is assigned a unique wavelength ID. Here, the wavelength ID is a natural number from 1 to 4. In the following description, the wavelength is represented by λ. For example, λ1 indicates a wavelength having a wavelength ID of 1.

  The wavelength multiplexed signals input through the input optical fibers 301a to 301d are demultiplexed into four demultiplexed signals having wavelengths λ1 to λ4 by the first to fourth demultiplexers 321a to 321d. Each demultiplexed signal is transmitted to the optical switch unit 333 via the termination unit 331. The terminating unit 331 has a function of extracting a demultiplexed signal from the demultiplexers 321a to 321d and sending it to the router 350, and a function of sending the optical signal sent from the router 350 to the optical switch unit 333. It can be realized by a known OADM (Optical Add Drop Multiplexing) apparatus. Here, since the node includes four input optical fibers 301a to 301d, each of which is demultiplexed into four demultiplexed signals, there are 16 demultiplexed signals input to the termination unit 331. The termination unit 331 can be configured by including an OADM device in each of the optical paths through which the 16-line demultiplexed signals pass. Each OADM device switches between a passing (cut-through) state and a terminal state in response to a terminal control signal from the control device 335. Here, the cut-through state is a state in which the demultiplexed signals input from the demultiplexers 321 a to 321 d are sent directly to the optical switch unit 333 without passing through the router 350. In the termination state, the demultiplexed signals input to the termination unit 331 from the demultiplexers 321a to 321d are sent to the router 350, and the optical signal received from the router 350 is sent from the termination unit 331 to the optical switch unit 333. The state, that is, the state where the optical signal of each wavelength is relayed by the router.

  The demultiplexed signal input to the optical switch unit 333 is output to any one of the first to fourth multiplexers 326a to 326d. Since the switching of the optical path of the demultiplexed signal is performed for each of the 16 demultiplexed signals, the optical switch unit 333 can be configured to include 16 1 × 4 optical switch devices. Here, the 1 × 4 optical switch device selects and outputs one of four channels with respect to one input, and any suitable known device can be used. Each 1 × 4 optical switch device responds to the switching control signal from the control device 335 and transmits the optical signal sent from the termination unit 331 to any one of the first to fourth multiplexers 326a to 326d. Output.

  The first to fourth multiplexers 326a to 326d multiplex, that is, wavelength multiplex, the input optical signals. In the first to fourth multiplexers 326a to 326d, the first to fourth output optical fibers 306a to 306d have a one-to-one correspondence, and wavelength-multiplexed optical signals are output from the output optical fibers.

  Input / output is performed between the input optical fibers 301a to 301d and the corresponding demultiplexers 321a to 321d, and between the multiplexers 326a to 326d and the corresponding output optical fibers 306a to 306d. An amplifier for amplifying the wavelength multiplexed optical signal may be provided.

  The packet received by the node from the external network 360 is sent to the router 350 via the traffic measuring device 357. The traffic measurement device 357 has a function of acquiring transmission source and destination information such as an IP address and the transmission amount of the packet as traffic from the packet, and transmits the traffic measurement result to the management device 270 via the measurement line 253. To do. Any suitable known device can be used as the traffic measuring device 357.

  The router 350 includes first to fourth internal interfaces 351a to 351d, and outputs received packets via any of the internal interfaces 351a to 351d in accordance with route information included in the router 350. The router 350 may be any suitable known one.

  The packet output from the router 350 is converted from an electrical signal to an optical signal by the conversion devices 353 a to 353 d and sent to the termination unit 331. Here, the conversion devices 353a to 353d are provided in a one-to-one correspondence with the first to fourth internal interfaces 351a to 351d. The packet output from the first internal interface 351a is converted into an optical signal having the wavelength λ1 by the first converter 353a. The packet output from the second internal interface 351b is converted into an optical signal having the wavelength λ2 by the second conversion device 353b. The packet output from the third internal interface 351c is converted into an optical signal having the wavelength λ3 by the third converter 353c. The packet output from the fourth internal interface 351d is converted into an optical signal having the wavelength λ4 by the fourth converter 353d. The converted optical signal is sent to the optical switch unit 333 through the OADM device of the termination unit 331, and is output from a predetermined output optical fiber.

  Further, since the packet sent from the termination unit 331 to the router 350 is an optical signal of any of the wavelengths λ1, λ2, λ3, and λ4, these optical signals are converted into signals that can be processed by the IP router. For example, when the signal that can be processed by the router 350 is an electrical signal, the first to fourth conversion devices 353a to 353d may be configured to include an electrical-optical converter and an optical-electrical converter.

  The setting signal sent from the management device 270 to each node includes a route rewriting signal for rewriting route information included in the router 350, a termination control signal for the termination unit 331, and a switching control signal for the optical switch unit 333. The setting signal is sent from the management device 270 to the control device 335 via the setting line 251. In response to receiving the setting signal, the control device 335 transmits a path rewrite signal, a termination control signal, and a switching control signal to the router 350, the termination unit 331, and the optical switch unit 333, respectively.

(Optimum optical path search device)
FIG. 4 is a schematic configuration diagram for explaining the management device 270. As the management device 270, a well-known computer or the like that includes an MPU (Microprocessing Unit) 280, a storage unit 450, a transmission unit 271, a reception unit 273, and an input / output unit 277 can be used. The input / output unit 277 includes a known input device such as a keyboard and a mouse normally used in a computer, and a display device such as a display. As the storage unit 450, any suitable known storage device such as a hard disk is used. The MPU 280 may have a well-known configuration. In this example, the MPU 280 includes a central processing unit (CPU) 400, a RAM (Random Access Memory) 283 as a memory, and a ROM (Read Only Memory) 281. Yes. Note that the storage unit 450 can also be provided in the RAM 283.

  The control means 403 provided in the CPU 400 reads out a program recorded in the ROM 281 or the like so as to be readable, and executes the program to thereby function as a traffic monitoring means 411, an objective function value determination means 413, and an end as a function means of the CPU 400. The condition determining unit 415, the optimum optical path searching unit 420, and the optical path arrangement changing unit 440 are realized. The management device 270 functions as an optimal optical path search device by including the optimal optical path search means 420.

  The optimum optical path search unit 420 further includes an initialization unit 421, a minimum optical path selection unit 423, a connectivity determination unit 425, an optical path change unit 427, an interface (IF) number determination unit 429, and a random number generation unit 431. ing. Details of processing performed by each functional unit will be described later.

  The receiving unit 273 can be any suitable known input interface. The traffic measurement results at the nodes (N1 to N9) sent to the management device 270 are sent to the traffic monitoring means 411 via the receiving unit 273.

  The traffic monitoring unit 411 creates a traffic matrix 458 as a table of transmission / reception traffic between nodes as traffic information based on the received traffic measurement result. The traffic matrix 458 is stored in the storage unit 450 so as to be readable. Details of the traffic matrix 458 will be described later.

  The optical path arrangement changing unit 440 performs a transition process from the currently set working optical path arrangement to the optimum optical path arrangement searched by the optimum optical path searching unit 420. Although details of the migration process will be described later, the optical path arrangement changing unit 440 further includes an unnecessary optical path selecting unit 443, a connectivity determining unit 445, an unnecessary optical path releasing unit 441, and a necessary optical path setting unit 447. ing.

  Here, the management device 270 has been described as a configuration including a traffic monitoring device, an optimum optical path search device, and an optical path setting device, but a computer having the same configuration as that described with reference to FIG. It is possible to use another device using In this case, the traffic monitoring apparatus includes traffic monitoring means as functional means, and the optimal optical path arrangement search apparatus includes objective function value determination means, termination condition determination means, and optimal optical path search means as functional means, The path setting device may be configured to include an optical path arrangement changing unit as a function unit. The storage unit 450 may be shared, or data may be transmitted and received via a transmission unit and a reception unit included in each of the traffic monitoring device, the optimum optical path search device, and the optical path setting device.

(Optimum optical path search method)
The optimum optical path search method will be described with reference to FIGS. FIG. 5 is a diagram showing a processing flow in the management apparatus. FIG. 6 is a diagram showing an optimal optical path search flow.

  In step (hereinafter, step is represented by S) 10, the traffic monitoring means 411 monitors traffic at each node of the internal network. The traffic monitoring unit 411 collects traffic measurement results measured at each node (N1 to N9), and periodically creates a traffic matrix 458 based on the measurement results. The created traffic matrix 458 is stored in the storage unit 450 so as to be readable.

  In S20, the objective function value determination unit 413 determines whether the objective function value satisfies a specified value. The objective function value determination unit 413 reads the traffic matrix 458 and the working path table 452 recorded in the storage unit 450 and applies them to the objective function 454 that is also read from the storage unit 450 to obtain the objective function value. calculate. Here, the sum of relay traffic at each node is used as an objective function. In the working path table 452, setting information such as a termination node of the working optical path arrangement is recorded. For example, when there is no optical path directly connecting N1 and N2 in the working optical path arrangement, in order to transmit a packet from N1 to N2, transmission is performed by using a combination of the optical paths existing in the working optical path arrangement. Here, the packet is transmitted from N1 to N4 using one optical path, and then the packet is transmitted from N4 to N2 using another optical path. In this case, the traffic transmitted from N1 to N2 is relayed by the node 4. Similarly, for all combinations of destination nodes and destination nodes, the relay traffic is obtained by adding the traffic to be relayed for each node and further adding the traffic between the external network and the router. The calculation result of the relay traffic is recorded in a readable manner in the RAM 283, for example.

  The objective function value determination unit 413 reads the relay traffic at each node recorded in the RAM 283 and the like and the specified value recorded in advance in the ROM 281 and compares them. For example, for each node, the specified value is determined based on the maximum amount of traffic that can be relayed by a router included in the node. When there is a node whose relay traffic exceeds a specified value, there is a possibility that congestion occurs in the node. In this case, the optimum optical path search process of S30 is subsequently performed. On the other hand, if the relay traffic is less than the specified value in all nodes, the traffic is monitored again in S10.

  Details of the optimal optical path search process will be described with reference to FIG. The optimum optical path search process includes steps S110 to S160.

  In the initialization process of S110, the initialization unit 421 virtually sets initial optical paths for all combinations of nodes. FIG. 7 is a diagram showing an initial optical path set in the initialization process, and shows only an initial optical path having N1 as a termination node. In the initialization process, an initial optical path is set between other nodes as well as N1 for N2 to N9.

  The initialization unit 421 creates the interface table 462 and creates the path table 460 based on the traffic matrix 458. With reference to FIG. 8, the traffic matrix, path table, and interface table in the initial state will be described. The traffic matrix, path table, and interface table may be collectively referred to as a data table. FIGS. 8A, 8B, and 8C are diagrams for explaining a traffic matrix, a path table, and an interface table in an initial state, respectively.

  In the traffic matrix 458a in the initial state, the traffic to each destination node is shown in a matrix for each source node measured at each node. Therefore, when one node is selected from each node of the transmission source and each node of the destination, traffic from the transmission source node to the destination node can be obtained (FIG. 8A).

  The path table 460a includes a termination node, a traffic amount, and a flag for each path ID. Different path IDs are assigned to all combinations of nodes. The optical path is represented by P, for example, P1 represents an optical path having a path ID of 1. P1 has terminal nodes N1 and N2. According to the traffic matrix 458a, traffic whose source node is 1 and whose destination node is 2 is 1, traffic whose source node is 2 and whose destination node is 1 is 4. . Therefore, the traffic of P1 is 5 (= 1 + 4). Similarly, traffic is calculated for each optical path to create a path table. In the initialization process, all optical paths are initial optical paths, and the initial optical path flag is set to 0 (FIG. 8B).

  The interface table 462a includes data on the number of interfaces (IF) for each node. Here, since there are nine nodes, when an optical path is set from one node to all other nodes, a maximum of eight optical paths are set. In this case, since 8 interfaces are used, all the IF numbers in the interface table 462a are set to 8. The number of interfaces is virtually determined.

  In the minimum optical path selection process of S120, the minimum optical path selection unit 423 selects the optical path with the minimum traffic as the minimum optical path among the initial optical paths. Specifically, the minimum optical path selection unit 423 selects the optical path with the minimum traffic among the optical paths with the flag 0 from the path table 460a. In the initialized path table 460a, for example, P8 with traffic 1 is selected as the minimum optical path. Here, in the case where there are a plurality of optical paths with the minimum traffic among the initial optical paths, one initial optical path may be selected by any suitable method, for example, random selection is performed using a random number. be able to. The random number is generated by reading out a random number table that is readably written in the ROM 281 or the like by the random number generation means 431. In addition, there is a method in which the traffic saved at the time of cancellation of the initial optical path is examined for the influence on other nodes, and one having a low load is selected.

  In the connectivity determination process of S130, the connectivity determination unit 425 determines whether or not the minimum optical path can be released, that is, whether or not the connectivity of the optical topology is maintained even if the minimum optical path is released. Do. Here, since the minimum optical path is P8, the reachability of the packet when the optical path between N1 and N9 is released is examined. In the initialized state, since an optical path is set between all the nodes, an IP path is set between N1 and N9 using an optical path from N1 to N8 and an optical path from N8 to N9. Yes, that is, P8 can be released.

  Next, an optical path changing process is performed. The optical path changing process includes steps S140 and S150.

  If the minimum optical path cannot be canceled as a result of the determination in the connectivity determination process, the minimum optical path is changed to a non-release optical path in S140, and then the minimum optical path selection process in S120 is performed again. In order to change the minimum optical path to a non-released optical path, the flag of the corresponding optical path in the path table is set to 2. Here, since the minimum optical path is P8, the optical path changing unit 427 sets the flag of P8 to 2.

  On the other hand, if the result of determination in the connectivity determination process is that the minimum optical path can be released, the minimum optical path is changed to the release optical path in S150, and the traffic of the release optical path is saved to another path. Let Here, the optical path changing unit 427 sets the flag of P8 to 1, and moves the traffic of the release optical path to the initial optical path or the non-release optical path, that is, updates the traffic matrix by saving the traffic.

  With reference to FIG. 9, a case where P8 which is the minimum optical path is canceled and the traffic of P8 is saved to the path of N1-N8-N9 will be described. FIG. 9 is a diagram for explaining a data table in a state where an optical path is released. FIGS. 9A, 9B, and 9C show a traffic matrix, a path table, and an interface table, respectively. Yes.

  Since the traffic from N1 to N9 of P8 is 0, the traffic from N1 to N8 and the traffic from N8 to N9 do not change even after the traffic from N1 to N9 is saved. On the other hand, since the traffic from N9 to N1 of P8 is 1, the traffic from N9 to N8 and the traffic from N8 to N1 increase by 1, respectively. As a result of this evacuation, there is no traffic from N1 to N9 and no traffic from N9 to N1, so both become 0 (FIG. 9A).

  Along with the update of the traffic matrix 458b, the path table 460b is updated. The traffic corresponding to P8 becomes 0, and 1 is added to the traffic of the optical path between N1 and N8 and the optical path between N8 and N9. Moreover, the flag of P8 is set to 1 by the cancellation | release of P8 (FIG. 9 (B)).

  Further, the interface table 462b is updated with the update of the path table 460b. Since P8 becomes a release optical path, the number of paths having N1 and N9 as termination nodes is reduced by one. Therefore, the number of IFs in the interface table is also subtracted by 1 for N1 and N9 (FIG. 9C).

  In the interface number determination process in S160, it is determined whether the number of interfaces used in each node satisfies the usable interface number condition. When the number of IFs used in each node satisfies the usable interface number condition, the optimum optical path search process is terminated. On the other hand, if not, the minimum optical path selection process of S120 is performed. For example, in the case of the node described with reference to FIG. 3, since four internal interfaces are provided, the number of usable interfaces is four. The optimum optical path searching unit 420 repeatedly performs the processes from S120 to S160 until the number of interfaces used in each node satisfies the usable interface number condition, that is, until all the interfaces in the interface table become 4 or less. With reference to FIG. 10, the data table in a state where the optimum optical path search process has been completed will be described. FIGS. 10A and 10B show a path table and an interface table in an end state, respectively.

  In the path table 460c in the end state, the flag of the release optical path is 1, and the flag of the non-release optical path is 2. When the optimum optical path search process is completed, the optical path that has not been selected as the minimum optical path remains as the initial optical path with the flag remaining at 0 (FIG. 10A).

  In the interface table 462c in the end state, the number of IFs is 4 or less, which is the number of usable interfaces, for all the nodes (FIG. 10B).

  As described above, according to the optimum optical path searching apparatus and the optimum optical path searching method of the present invention, the initial optical path is virtually set for all combinations of nodes, and traffic is maintained while maintaining packet reachability. Since the initial optical path is canceled in ascending order, the optimum optical path arrangement can be obtained efficiently.

  In the termination condition determination process of S40, the termination condition determination unit 415 reads the termination condition 456 recorded in advance in the storage unit 450, and the optical path arrangement obtained as a result of performing the optimum optical path search process is the termination condition 456. It is determined whether or not The termination condition determination unit 415 calculates an objective function value for the obtained optical path arrangement by the same process as in step S20, and compares it with a specified value. If the objective function value is less than or equal to the specified value, it is determined that the end condition 456 is satisfied, and the optical path arrangement changing process of S50 is performed. If the objective function value is not less than or equal to the specified value, the process is terminated without performing the optical path arrangement changing process. Here, the termination condition can be arbitrarily set according to the network configuration and the like, and even if the objective function value is not less than the specified value, it is less than the objective function value in the working optical path arrangement. If it is, it may be set to determine that the end condition is satisfied.

  In the optical path arrangement changing process of S50, the optical path arrangement changing means 440 compares the working optical path arrangement with the optimum optical path arrangement. This comparison is performed by reading the working path table 452 and the end state path table 460 from the storage unit 450. Here, the optical path set in the working optical path arrangement and the optical path set in the optimum optical path arrangement is not set in the used optical path and the working optical path arrangement, but is set in the optimum optical path arrangement. Are set in the set optical path and the working optical path arrangement, but are not set in the optimum optical path arrangement, respectively.

  In the optical path arrangement changing process, the optical path arrangement of the internal network is shifted from the working optical path arrangement to the optimum optical path arrangement. This transition is performed by sending each node setting signal from the management apparatus 270 via the transmission unit 271. In the optical path arrangement changing process, the used optical path is maintained as it is. Further, the non-set optical path is released from the working optical path arrangement, and the set optical path is set in the internal network using the network resource obtained as a result of the release. Any suitable method can be used as a method of releasing the non-setting optical path from the working optical path arrangement and setting the setting optical path, for example, as follows.

  First, the unnecessary optical path selection unit 443 selects a non-set path with the least traffic as an unnecessary path.

  Next, the connectivity determination unit 445 determines whether the connectivity is maintained when the unnecessary optical path is released. When the connectivity is maintained, the unnecessary optical path canceling unit 441 releases the unnecessary optical path from the internal network by transmitting a setting signal to each node and switching the settings of the termination unit 331 and the optical switch unit 333. To do. If the connectivity is not maintained, the unnecessary optical path selection unit 443 selects the next least traffic as an unnecessary optical path, and the connectivity determination unit 445 determines whether the connectivity is maintained again. Is confirmed.

  Next, the necessary optical path setting unit 447 sets the set optical path for the internal network using the network resources that have become available by releasing the unnecessary optical path from the internal network. Here, the maximum traffic among the set optical paths is selected as the necessary optical path. If the selected required optical path cannot be set, the next set optical path having the next highest traffic is selected as the required optical path and set.

  In this way, while maintaining connectivity, the non-configured optical paths are released in ascending order of traffic, and the network resources obtained as a result of the release are used in order from the set optical path in descending order of traffic. When the setting is made, it is possible to shift from the working optical path arrangement to the optimum optical path arrangement for the entire network while ensuring the reachability of the packet. In addition, since a necessary path with a lot of traffic is set with priority and an unnecessary path with a small amount of traffic is released first, the possibility of causing a packet loss at the time of path arrangement transition can be further reduced.

It is a schematic block diagram of an internal network. It is a schematic block diagram of a control network. It is a schematic block diagram of a node. It is a schematic block diagram of a management apparatus. It is a figure which shows the processing flow in a management apparatus. It is a figure which shows the optimal optical path search flow. It is a figure which shows the initial stage optical path set in the initialization process. It is a figure which shows the data table of an initial state. It is a figure which shows the data table of the state which cancelled | released the optical path. It is a figure which shows the data table of an end state.

Explanation of symbols

250 Control Line 251 Setting Line 253 Measurement Line 270 Management Device 271 Transmitter 273 Receiver 277 Input / Output Unit 280 MPU
281 ROM
283 RAM
301a, 301b, 301c, 301d Input optical fiber 306a, 306b, 306c, 306d Output optical fiber 321a, 321b, 321c, 321d Demultiplexer 326a, 326b, 326c, 326d Multiplexer 330 Optical path switching unit 331 Termination unit 333 Optical switch Unit 335 Control device 350 Router 351a, 351b, 351c, 351d Internal interface 353a, 353b, 353c, 353d Conversion device 357 Traffic measurement device 360 External network 400 CPU
403 Control unit 411 Traffic monitoring unit 413 Objective function value determination unit 415 Termination condition determination unit 420 Optimal optical path search unit 421 Initialization unit 423 Minimum optical path selection unit 425 Connectivity determination unit 427 Optical path change unit 429 IF number determination unit 431 Random number generation means 440 Optical path arrangement change means 441 Unnecessary optical path cancellation means 443 Unnecessary optical path selection means 445 Connectivity determination means 447 Required optical path setting means 450 Storage unit 452 Current path table 454 Objective function 456 Termination condition 458 Traffic matrix 460 path Table 462 Interface table

Claims (2)

An optimal optical path search device for searching for an optimal optical path arrangement in an optical network comprising a plurality of nodes and an optical fiber that connects adjacent nodes and transmits a wavelength multiplexed optical signal,
Traffic monitoring means for generating a traffic matrix based on traffic information obtained from the plurality of nodes;
Initialization means for setting an initial optical path for virtually all combinations of nodes;
Among the initial optical paths, minimum optical path selection means for selecting the optical path with the minimum traffic as the minimum optical path;
Connectivity determination means for determining whether or not the minimum optical path can be canceled;
When the minimum optical path cannot be canceled, the minimum optical path is changed to a non-released optical path. On the other hand, when the minimum optical path can be canceled, the minimum optical path is changed to a released optical path. And an optical path changing means for saving traffic of the release optical path;
An interface number determination means for determining whether or not the number of interfaces used in each node satisfies a usable interface number condition ;
An optimum optical path search apparatus comprising: an optical path arrangement changing means for performing a transition process from the currently set optical path arrangement to the optimum optical path arrangement . In an optical network comprising a plurality of nodes and an optical fiber that connects adjacent nodes and transmits a wavelength multiplexed optical signal, based on a traffic matrix generated based on traffic information obtained from the plurality of nodes In searching for the optimal light path arrangement,
An initialization process for setting an initial optical path for a combination of virtually all nodes;
Among the initial optical paths, a minimum optical path selection process for selecting an optical path with the least traffic as a minimum optical path;
A connectivity determination process for determining whether or not the minimum optical path can be canceled;
As a result of the determination, if the minimum optical path is not cancelable, the minimum optical path is changed to a non-cancel optical path. On the other hand, if the minimum optical path is cancelable, the minimum optical path is changed. An optical path change process for changing to a release optical path and saving traffic on the release optical path;
An interface number determination process for determining whether or not the number of interfaces used in each node satisfies a usable interface number condition;
Until interface number satisfying the minimum light path selection process, the connectivity determination process, the light after the path changes Tsu process and line repeating the interface number determination process, the optimum light from the light path arrangement that is currently set A method for searching for an optimum optical path, characterized by performing a process of transition to path arrangement .

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