JP2012050045A - Route table creation device and route table creation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a burden of creation processing of a route table including an alternative route in the occurrence of a failure within a network.SOLUTION: Using reachability information 132 indicating a device reachable to each destination address and topology information 133 of a communication network, a route table creation device creates a route table 133 including a first transfer destination (active) and a second transfer destination (preliminary) to be used at the devices of the communication network, for each of the devices. Then, the created route table 133 is transmitted to each device 40.

Description

  The present invention relates to a technology for creating a routing table used for determining a destination address or a transfer destination for a subnetwork in each router or the like of an IP (Internet Protocol) network.

  Conventionally, a route table used by each device such as a router in an IP network for packet transfer is created by each device using a routing protocol such as OSPF (Open Shortest Path First) or BGP (Border Gateway Protocol) (non-patented). References 1 and 2). In addition, when a failure occurs in a device in the network or a link connecting each device, switching to the detour route is performed at high speed. Therefore, in each device, the transfer path before the failure (first transfer path) In addition to the above, a technique for calculating in advance a second transfer path that is a detour path has also been proposed.

IETF RFC2328 “OSPF Version 2”, April 1998. IETF RFC 4271, “A Border Gateway Protocol 4 (BGP-4)”, January 2006.

  However, according to the prior art, there is a problem that a processing load is large when a routing protocol is operated in each device and a route table including a detour route is created. In particular, when the topology is such that each device in the network is connected to many other devices (for example, a topology in which each device in the network is connected by a full mesh), the routing table in each device. The load of the creation process is extremely large. Furthermore, an object of the present invention is to solve the above-described problems and to reduce the load of processing for creating a route table including a detour route when a failure occurs in the network.

  In order to solve the above-described problems, in the present invention, a routing table creation device that creates a routing table used for packet transfer processing in each device in the network performs the following processing. That is, for each destination address, this routing table creation device accepts input of reachability information indicating identification information of a device at the destination address or a device that can reach the subnetwork, and stores it in the storage unit. In addition, input of topology information indicating a connection state of each device configuring the network and a link connecting each device is received and stored in the storage unit. Then, for each destination address indicated in the reachability information, this routing table creation device selects an active device and a spare device from a group of devices that can reach the destination address. Then, for each of the devices indicated in the topology information, the route table creation device calculates a working route from the starting point device to the working device that can reach the destination address when the device is the starting point device. Also, a backup route from the start point device to the backup device that can reach the destination address is calculated. Then, referring to the topology information, a working link that is a link used by the starting point device in the working route and a backup link that is a link used in the backup route are selected. Thereafter, the routing table creation device creates a routing table indicating the working link and the protection link to the destination address for each destination address for each of the start point devices. Then, the routing table creation device transmits the created routing table to each device that is the starting point device.

  In this way, the routing table creation device creates a routing table for each device including a detour route when a failure occurs in the network, so that it is not necessary for each device to create a routing table by operating a routing protocol.

  In the present invention, a routing table creation device that creates a routing table used for packet transfer processing in each device in the network performs the following processing. That is, this route table creation device accepts the input of reachability information and stores it in the storage unit. Also, input of topology information including the connection state of each device constituting the network, the link connecting each device, and, when the link is a working link used for a working route, identification information of a backup link for the link Is stored in the storage unit. Then, for each destination address indicated in the reachability information, the routing table creation device selects an active device from a group of devices that can reach the destination address. Next, for each of the devices indicated in the topology information, when the device is the start point device, a working path from the start point device to the active device that can reach the destination address is calculated. Then, referring to the topology information, a working link used for the working route is selected, and a backup link for the selected working link is selected in the topology information. Thereafter, the routing table creation device creates, for each destination address, a routing table indicating the working link and the protection link to the destination address for each destination address. Then, the routing table creation device transmits the created routing table to each device that is the starting point device.

  In this way, the routing table creation device creates a routing table for each device including a detour route when a failure occurs in the network, so that it is not necessary for each device to create a routing table by operating a routing protocol. Further, according to this routing table creation device, the route table is created by selecting the backup link paired with the working link on the topology information, so that the processing load for creating the routing table can be reduced.

  In the present invention, a routing table creation device that creates a routing table used for packet transfer processing in each device in the network performs the following processing. That is, this routing table creation device accepts input of reachability information and topology information and stores them in the storage unit. The route table creation device searches the device group constituting the ring with reference to the topology information until two or more reachable devices to the same destination address indicated in the reachability information are included in any one of the rings. Then, with reference to the reachability information, for each device group constituting the ring, a destination address group in which the device group is an edge node is extracted. Next, the routing table creation device refers to the topology information, and for each device in the device group that constitutes the ring, when the device is the starting point device, the first rotation direction in the ring constituted by the device group The link connected to the device is selected as the working link. In addition, (2) a link connected to a device having a rotation direction opposite to the first rotation direction in the ring is selected as a spare link. Thereafter, the routing table creation device creates a routing table for each destination address indicated in the destination address group for each starting point device, and shows a working link and a backup link to the destination address. Then, the routing table creation device transmits the created routing table to each device that is the starting point device.

  In this way, the routing table creation device creates a routing table for each device including a detour route when a failure occurs in the network, so that it is not necessary for each device to create a routing table by operating a routing protocol. Further, according to this route table creation device, when there is a device group connected in a ring shape in the topology information, it is connected in the first rotation direction (for example, clockwise direction) as seen from the start point device in the topology information. Link as the working link to the destination address. In addition, a link connected to a device having a rotation direction opposite to the first rotation direction (for example, a counterclockwise direction) is selected as a spare link to the destination address. For example, in the case where the devices A, B, C, and D are connected in a ring shape, if the device B is connected in the clockwise direction when viewed from the device A, the routing table creation device is changed from the device A to the device. The link to B is selected as the working link from device A to the destination address. Further, the link from the device A to the device C is selected as a backup link from the device A to the destination address. By doing so, the routing table creation device can reduce the processing load for creating the routing table.

  In the present invention, a routing table creation device that creates a routing table used for packet transfer processing in each device in the network performs the following processing. That is, this routing table creation device accepts input of reachability information and topology information and stores them in the storage unit. Then, when a plurality of devices having a plurality of destination addresses are registered in the reachability information and at least a part of the destination address group set between the devices is the same, the routing table creation device A destination group that is a set of destination addresses is calculated. Next, for each destination address indicated in the reachability information, the routing table creation device selects an active device and a spare device from a group of devices that can reach the destination address. Then, for each of the devices indicated in the topology information, the route table creation device calculates a working route from the starting point device to the working device that can reach the destination address when the device is the starting point device. Also, a backup route from the start device to the backup device that can reach the destination address is calculated. Then, referring to the topology information, a working link that is a link used by the starting point device in the working route and a backup link that is a link used in the backup route are selected. Thereafter, the routing table creation device creates a routing table showing the working link and the protection link to the destination address of the destination group for each destination address of the calculated destination group for each of the start point devices. Then, the routing table creation device transmits the created routing table to each device that is the starting point device.

  In this way, the routing table creation device does not need to obtain a working link and a backup link for each destination address. That is, since it is not necessary to select the working link and the protection link for each destination address from the starting point device, the processing load for creating the routing table can be reduced.

  In addition, when calculating the working route and the backup route, the link selection unit of the route table creation apparatus according to the present invention refers to the topology information and calculates the route that minimizes the number of hops or the link cost.

  By doing in this way, the route table creation device can create a route table of a route that minimizes the number of hops or link cost from the starting point device to the active device (or spare device).

  In addition, the link selection unit of the routing table creation device of the present invention refers to topology information when calculating the working route and the backup route, and selects the route in which the working route and the protection route do not pass through the same device or link. To do.

  In this way, the routing table creation device can create a routing table including a backup route that is not easily affected by the failure even when a failure occurs on the working route.

  In addition, when selecting a working device, the device selection unit of the routing table creation device of the present invention refers to the topology information and selects a device with the smallest number of hops or link cost to the destination address.

  In this way, the routing table creation device can create a routing table for a route that minimizes the number of hops or link cost from the starting point device to the active device.

  ADVANTAGE OF THE INVENTION According to this invention, the load of the preparation process of the routing table containing the detour route at the time of the failure occurrence in a network can be reduced.

(A) is the figure which illustrated the whole structure of the system of each embodiment, (b) is the figure which illustrated the topology of the communication network. (A) is the figure which showed notionally the process outline | summary of the routing table preparation apparatus of 1st Embodiment, (b) is the figure which illustrated reachability information. (C) is a diagram illustrating topology information, and (d) is a diagram illustrating a routing table. It is the figure which showed the structure of the routing table preparation apparatus of 1st Embodiment and 2nd Embodiment. It is the flowchart which showed the process sequence of the routing table preparation apparatus of 1st Embodiment. (A) is the figure which showed the example of the topology of a communication network, and the process outline | summary of the routing table preparation apparatus of 2nd Embodiment notionally, (b) is the figure which illustrated reachability information. . (C) is a diagram illustrating topology information, and (d) is a diagram illustrating a routing table. It is the flowchart which showed the process sequence of the routing table preparation apparatus of 2nd Embodiment. (A) is the figure which showed the example of the topology of a communication network, and the process outline | summary of the routing table preparation apparatus of 2nd Embodiment notionally, (b) is the figure which illustrated reachability information. . (C) is a diagram illustrating topology information, and (d) is a diagram illustrating a routing table. It is the figure which showed the structure of the routing table preparation apparatus of 3rd Embodiment. It is the flowchart which showed the process sequence of the routing table preparation apparatus of 3rd Embodiment. (A) is the figure which showed notionally the process outline | summary of the routing table preparation apparatus of 4th Embodiment, (b) is the figure which illustrated reachability information. (C) is a diagram illustrating topology information, and (d) is a diagram illustrating a routing table. It is the figure which showed the structure of the routing table preparation apparatus of 4th Embodiment. It is the flowchart which showed the process sequence of the routing table preparation apparatus of 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described by dividing them from the first embodiment to the fourth embodiment with reference to the drawings. First, an example of the overall configuration of a system common to the routing table creation apparatuses 10, 10A, 10B, and 10C of each embodiment will be described with reference to FIG.

  As shown in FIG. 1A, the system includes a communication network, a route table creation device 10, and a network information acquisition device 20. This communication network is an IP network in which a plurality of devices 40 (for example, nodes such as IP routers) are connected by links (for example, optical fibers). The routing table creation devices 10, 10 </ b> A, 10 </ b> B, and 10 </ b> C are based on information acquired from the network information acquisition device 20 (for example, information that is the basis of the topology information 131 and reachability information 132). Create a postscript). Then, this route table 133 is transmitted to each device 40, and each device 40 transfers a packet based on the received route table 133. The network information acquisition device 20 acquires information such as the connection status of each device 40 from the communication network, and transmits the information to the routing table creation devices 10, 10A, 10B, and 10C. The routing table creation devices 10, 10A, 10B, and 10C and the network information acquisition device 20 are realized by computers that can communicate using a communication protocol such as IP. The routing table creation devices 10, 10A, 10B, and 10C create a routing table 133 that includes a backup route of the working route in addition to the working route. As a result, each device 40 that has received this route table 133 can switch to a detour route (backup route) at a high speed when a failure occurs in the network.

<First Embodiment>
First, the routing table creation device 10 according to the first embodiment will be described. Here, a case where the routing table creation device 10 creates the routing table 133 of the communication network having the topology as shown in FIG. 1B will be described as an example. The devices A, B, C, and D in FIG. The devices A and B indicate that they can reach the destination addresses d1 and d2, respectively. The destination address may be an IP address of a destination device or a subnetwork address.

  As shown in FIG. 2A, the routing table creation device 10 has reachability information 132 (information indicating the device 40 of the edge node of the communication network that can reach the destination address for each destination address (FIG. 2). (See (b))) and the topology information 131 of the communication network (see FIG. 2 (c)), the route table is calculated, and the route table 133 of each device 40 in the communication network (see FIG. 2 (d)). ). The routing table 133 is information indicating, for each destination address (destination), a link to the first transfer destination (working link) to the destination address and a link to the second transfer destination (backup link). It is. That is, the route table 133 is information indicating both the working link and the protection link for the same destination address in order for the device 40 to realize high-speed switching to the detour route when a failure occurs in the communication network. 2D shows only the route table 133 of the devices C and D, the route table 133 of the devices A and B is similarly created.

  Next, the configuration of the routing table creation device 10 will be described with reference to FIG. The route table creation apparatus 10 is roughly divided into an input / output unit (input unit and output unit) 11, a processing unit 12, and a storage unit 13. The input / output unit 11 performs data transmission / reception with the network information acquisition device 20 and each device 40 of the communication network. For example, the base information of the topology information 131 and the reachability information 132 is acquired, or the route table 133 of each device 40 created by the route table creation device 10 is transmitted to each device 40. The processing unit 12 controls the entire route table creation device 10 and mainly creates the route table 133 of each device 40. The storage unit 13 stores various types of information that the processing unit 12 refers to when creating the route table 133 of each device 40.

  The input / output unit 11 includes an input / output interface, a communication interface capable of communicating by IP, and the like. The processing unit 12 is realized by a program execution process by a CPU (Central Processing Unit) included in the routing table creation device 10 (10A, 10B, 10C), a dedicated circuit, or the like. Further, the storage unit 13 includes a storage medium such as a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), and a flash memory. When the routing table creation devices 10, 10A, 10B, and 10C are realized by program execution processing, the storage unit 13 has a program for realizing the functions of the routing table creation device 10 (10A, 10B, and 10C). Stored.

  The storage unit 13 stores topology information 131 and reachability information 132. In addition, the storage unit 13 includes an area for storing the route table 133 of each device 40.

  As described above, the topology information 131 is information indicating a connection state of each device 40 configuring the communication network and a link connecting each device 40. For example, the topology information 131 shown in FIG. 2C is information indicating the topology of the communication network shown in FIG. 1B, and indicates that the apparatuses A and B are connected by the link # 1. The topology information 131 may include a link cost value for each link. Further, for example, the link used for communication from device A → device B and the link used for communication from device B → device A may be distinguished from each other, depending on the direction of communication.

  The reachability information 132 is information indicating identification information of a device 40 (reachable device) that can reach the device of the destination address or the subnetwork for each destination address. For example, the reachability information 132 shown in FIG. 2B is reachability information of the communication network shown in FIG. 1B, and the reachable devices to the destination address d1 are the devices A and B, and the destination address The devices that can reach d2 are also devices A and B. That is, when a packet is transferred to the destination addresses d1 and d2, the device 40 (starting device) of the communication network only needs to transfer the packet toward any one of the devices 40.

  The topology information 131 and the reachability information 132 are referred to when the routing table creation unit 123 creates the routing table 133. The topology information 131 and the reachability information 132 may be created by the processing unit 12 based on information received from the network information acquisition device 20, or information previously created by an external device may be input / output unit 11 You may enter via.

  The processing unit 12 includes a device selection unit 121, a link selection unit 122, a route table creation unit 123, and a route table transmission unit 124.

  The device selection unit 121 selects a working device and a standby device from among devices that can reach the destination address indicated in the reachability information 132 (see FIG. 2B). The identification information of each of the selected active device and spare device is output to the link selection unit 122. When the device selection unit 121 selects a working device and a spare device, if the reachability information 132 includes BGP (Border Gate Protocol) priority information, the device selection unit 121 uses the priority value. The device 40 may be selected. For example, in the reachability information 132, the device 40 having the highest BGP priority is selected as the active device among the devices that can reach the same destination address, and the device 40 having the next highest priority is selected as the spare device. Also good. Further, when selecting the working device and the spare device, the device selection unit 121 refers to the topology information 131 and selects the working device and the spare device based on the total number of hops from the starting device and the link cost. May be. For example, the device 40 having the smallest total number of hops and link costs from the starting device may be selected as the active device, and the next smallest device 40 may be selected as the spare device.

  For each of the devices 40 indicated in the topology information 131 (see FIG. 2C), the link selection unit 122 assumes that the device 40 is a starting device, and the working path (first transfer) from the starting device to the working device. Path) and a backup path (second transfer path) from the starting point device to the backup device. Then, referring to the link information shown in the topology information 131, the working link that is the link used by the start point device in the working route and the backup link that is the link used by the start point device in the backup route are selected. Then, the working link and the protection link of each selected device 40 are output to the route table creation unit 123. Further, when calculating the working route and the backup route, the link selection unit 122 may select the route having the smallest hop count or link cost when there are a plurality of routes to the same working device or the backup device. . In addition, referring to the topology information 131, a route in which the working route and the backup route do not pass through the same device 40 or link may be selected.

  The route table creation unit 123 creates a route table 133 (see FIG. 2D) indicating the working link and the spare link to the destination address for each device 40 for each device 40.

  The route table transmission unit 124 transmits the route table 133 of each device 40 to the device 40 of the communication network device via the input / output unit 11.

  By doing so, the routing table creation device 10 can create the routing table 133 of each device 40 and transmit it to each device 40.

<Processing procedure>
Next, the processing procedure of the routing table creation device 10 will be described with reference to FIGS.

  First, the device selection unit 121 of the routing table creation device 10 in FIG. 3 refers to the reachability information 132 and all reachable devices (for example, devices) for a certain destination address (for example, d1 in FIG. 2 (a)). A, B) are extracted (S11). That is, one destination address is selected from the destination addresses indicated in the reachability information 132, and all reachable devices (devices 40) for the destination address are extracted. Then, the device selection unit 121 selects an active device (for example, device A) and a standby device (for example, device B) from the extracted reachable devices (S12).

  Next, the link selection unit 122 selects one device 40 indicated in the topology information 131 (see FIG. 2C), and uses this device 40 (for example, device C) as a starting point device (for example, device). A working link (for example, link # 2) for reaching A) is selected. Further, a backup link (for example, link # 4) for reaching the backup device (for example, device B) from this starting point device is selected (S13). That is, first, the link selection unit 122 calculates a working path from the starting point device to the working device and a spare path from the starting point device to the spare device. Then, referring to the link information shown in the topology information 131, the working link that is the link used by the start point device in the working route and the protection link that is the link used in the protection route are selected. The routing table creation unit 123 stores the active link and the backup link of the selected starting point device in the routing table 133 related to the starting point device (device 40).

  Then, if all the devices 40 indicated in the topology information 131 have been processed (Yes in S14), and if all the destination addresses indicated in the reachability information 132 have been processed (Yes in S15), The routing table creation process ends. Then, the route table transmission unit 124 transmits the route table 133 to each device 40.

  On the other hand, if there is an unprocessed device 40 among the devices 40 indicated in the topology information 131 (No in S14), the device selection unit 121 performs the processing from S12 on the unprocessed device 40. If there is an unprocessed destination address for the destination address indicated in the reachability information 132 (No in S15), the device selection unit 121 executes the processing from S11 on for the unprocessed destination address.

  In this way, the routing table creation device 10 can create the routing table 133 used by each device 40 of the communication network. This route table 133 includes not only a link (working link) of each destination address to a working route but also a link (backup link) to a backup route. Therefore, each device 40 can switch the route to the detour route at high speed even when a failure occurs in the network.

<Second Embodiment>
Next, the routing table creation device 10A of the second exemplary embodiment will be described. Constituent elements similar to those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5A, the routing table creation device 10A performs reachability information 132 (see FIG. 5B) and topology information 131A (see FIG. 5C) when performing routing table calculation. It is characterized by referring to. As illustrated in FIG. 5C, the topology information 131A includes information indicating whether each link is a link used for a working path (working link) or a link used for a backup path (protection link). In addition, when the link is a working link, it includes identification information of a pair of protection links, and when the link is a protection link, identification information of a pair of working links is included. Then, after obtaining the working link of a certain device 40, the routing table creation device 10A selects the working link of the working link indicated in the topology information 131A when selecting the working link.

  As illustrated in FIG. 3, the processing unit 12 of the route table creation apparatus 10 </ b> A includes a device selection unit 121 </ b> A instead of the device selection unit 121 and a link selection unit 122 </ b> A instead of the link selection unit 122. Further, topology information 131A is provided instead of the topology information 131. The other configuration is the same as that of the routing table creation device 10, and thus the description thereof is omitted.

  For each destination address indicated in the reachability information 132, the device selection unit 121A selects a working device from a group of devices that can reach the destination address. The selected active device is output to the link selection unit 122A. When selecting this working device, for example, referring to the topology information 131A, the device with the smallest hop count or link cost to the destination address is selected.

  For each device 40 indicated in the topology information 131, the link selection unit 122A calculates a working path from the starting point device to the working device selected by the device selecting unit 121A when the device 40 is the starting point device. When the working link used for the working route is selected with reference to the topology information 131A, the protection link paired with the working link is selected with reference to the topology information 131A. The selected current link and backup link are output to the route table creation unit 123. If the topology information 131A does not include a spare link for the working link, the link selection unit 122A selects a spare device from devices that can reach the same destination address as the working device, as in the first embodiment. Then, the route to the spare device may be calculated to obtain the spare link.

<Processing procedure>
Next, the processing procedure of the routing table creation device 10A will be described with reference to FIGS. S21 is the same as S11 described above, and will be described from S22. The device selection unit 121A of the route table creation device 10A selects one device 40 from the reachable devices extracted in S21 (S22). For example, the device A shown in FIG.

  Next, for each device 40 indicated in the topology information 131A (see FIG. 5C), the link selection unit 122A sets the device 40 as a start device (for example, device C) from the start device in S22. A working link (for example, link # 2) for reaching the selected device 40 (for example, device A) is selected with reference to the topology information 131A (S23). That is, the link selection unit 122A calculates the working path from the starting point device to the working device with the device 40 selected in S22 as the working device. Then, referring to the link information indicated in the topology information 131A, the working link used in the starting point device is selected.

  Further, the link selection unit 122A refers to the topology information 131A and selects a backup link (for example, link # 5) of the link (working link) selected in S23 (S24). The routing table creation unit 123 records the active link and the backup link of the selected starting point device in the routing table 133 of the starting point device (for example, device C). Subsequent processes in S25 and S26 are the same as the processes in S14 and S15 described above, and thus the description thereof is omitted.

  According to such a routing table creation device 10A, when a backup link is selected, it is only necessary to select a backup link set on the topology information 131A, so that the processing load for creating the routing table can be reduced.

<Third Embodiment>
Next, a third embodiment will be described. Constituent elements similar to those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 7A, the routing table creation device 10B performs a ring search for searching for a device 40 connected in a ring shape on the topology when performing routing table calculation, and uses this ring as a forwarding destination. It is characterized by performing a calculation.

  For example, consider a case where the routing table creation device 10B uses a ring (devices A, B, C, and D) including devices A and B that are reachable to the destination addresses d1 and d2. In this case, as the working link from the device C to the destination address d1 (or d2), the link # 5 to the device D adjacent in the clockwise direction of the ring including the device C is selected. Further, the link # 2 to the device A adjacent in the counterclockwise direction of the ring is selected as the spare link. That is, if a ring including a plurality of devices that can reach a certain destination address is found on the topology, each of the devices 40 constituting the ring has two links to the destination address. Therefore, if one of the two links is a working link and the other link is a spare link, the working link and the spare link can be selected one by one.

  As shown in FIG. 8, the processing unit 12 of the routing table creation apparatus 10B has a link selection unit 122B, a routing table creation unit 123, a routing table transmission unit 124, a ring search unit 125, and a destination address extraction. Part 126.

  The link selection unit 122B refers to the link information shown in the topology information 131 (see FIG. 7C), and for each of the devices 40 in the device group constituting the ring, the link selection unit 122B is used when each device 40 is a start device. Select a link and a backup link. Details of the link selection processing of the link selection unit 122B will be described later with reference to FIG.

  The ring search unit 125 searches the topology information 131 for a group of devices constituting the ring until two or more reachable devices to the same destination address indicated in the reachability information 132 are included in any ring. As a result, each ring includes an active device and a spare device for the same destination address.

  The destination address extraction unit 126 refers to the reachability information 132 (see FIG. 7B) and arrives from a group of devices constituting the ring (for example, the devices A, B, C, and D in FIG. 7A). Possible destination address groups (for example, destination addresses d1 and d2) are extracted.

  Note that the routing table creation unit 123 performs, for each destination address (for example, destination addresses d1 and d2) indicated in the destination address group extracted by the destination address extraction unit 126, a working link and a spare used for transfer to the destination address. A route table 133 (see FIG. 7D) showing the links is created.

<Processing procedure>
Next, the processing procedure of the routing table creation device 10B will be described with reference to FIGS.

  First, the ring search unit 125 of the routing table creation device 10B in FIG. 8 refers to the reachability information 132 and the topology information 131, and a group of devices connected in a ring shape (for example, the devices A and A in FIG. 7A). B, C, D) are searched (S31). In searching for a group of devices connected in a ring shape, the reachability information 132 is referred to, and the ring includes two or more reachable devices to the same destination address (for example, the destination address d1). Explore things.

  The destination address extraction unit 126 refers to the reachability information 132 and extracts destination addresses (for example, destination addresses d1 and d2) that can be reached from a group of devices (for example, devices A, B, C, and D) constituting the ring. (S32).

  The link selection unit 122B sets the working link from a certain device 40 to the destination address group (for example, the destination addresses d1 and d2) extracted in S32 among the devices 40 constituting the ring searched in S31 in the clockwise direction of the ring. The link selection unit 122B determines the working link from the device 40 to the destination address group extracted in S32 in the counterclockwise direction of the ring (S34). That is, the link selection unit 122B uses a certain device 40 (for example, the device C) as a starting point device among the devices 40 (for example, the devices A, B, C, and D) constituting the ring searched in S31, and the starting point device. The link (for example, link # 5) to the device 40 (for example, device D) connected in the clockwise direction of the ring is selected as the working link. Further, the link selection unit 122B selects a link (for example, link # 2) to be connected to the device 40 (for example, the device A) connected counterclockwise from the starting point device as a spare link. Then, the routing table creation unit 123 sets the selected current link and backup link in the transfer destination column of the destination address group (for example, destination addresses d1 and d2) in the routing table 133 related to the source device (device 40). Remember.

  Here, the processing is finished for all the devices 40 (for example, devices A, B, C, and D) constituting the ring searched in S31 (Yes in S35), and all the destination addresses indicated in the reachability information 132 are displayed. If two or more reachable devices belong to one of the ring device groups (Yes in S36), the routing table creation process is terminated.

  On the other hand, if there is an unprocessed device 40 among the devices 40 (for example, devices A, B, C, and D) constituting the ring searched in S31 (No in S35), the process after S33 is performed on the unprocessed device 40. Perform the process. Further, among the reachable devices indicated in the reachability information 132, among the destination addresses indicated in the reachability information 132, there are those whose reachable devices do not belong to any of the ring device groups (2 or more) ( No in S36), the processing after S31 is executed.

  By doing so, the routing table creation device 10B determines the working link and the backup link of each device 40 in the direction on the ring when creating the routing table 133, thereby reducing the processing load for creating the routing table. it can.

<Fourth embodiment>
Next, a fourth embodiment will be described. Constituent elements similar to those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 10A, the route table creation apparatus 10C according to the fourth embodiment first performs reachability information 132 (see FIG. 10B) and topology information 131 (see FIG. 10B). The destination group is calculated with reference to FIG. 10C). This destination group is a group of destination addresses that can be reached from the same set of devices 40. Then, transfer destination calculation is performed using the destination group, and a route table 133 indicating the transfer destination of each device 40 is created.

  The calculation of the destination group will be described using a specific example. For example, the routing table creation device 10C refers to the reachability information 132 shown in FIG. 10B, and the communication network shown in FIG. Consider the case where route calculation is performed. In this case, d1 and d2 are set as reachable addresses for both apparatuses A and B in the reachability information 132 in FIG. 10B, and the destination groups are d1 and d2. Then, the routing table creation device 10C calculates the working route and the backup route from the device 40 serving as the starting point device to the destination address (destination address d1, d2) of this destination group. In this way, the route table creation apparatus 10C performs route calculation in units of destination groups, so that it is not necessary to perform route calculation in units of destination addresses. Thereby, the processing load for creating the routing table can be reduced.

  As shown in FIG. 11, the processing unit 12 of the routing table creation apparatus 10C has a device selection unit 121C, a link selection unit 122, a routing table creation unit 123C, a destination group calculation unit 127, and a routing table transmission. Part 124. Other configurations are the same as those of the routing table creation apparatus 10 described above, and thus the description thereof is omitted.

  The device selection unit 121C refers to the reachability information 132 for each destination group calculated by the destination group calculation unit 127, and selects a working device and a spare device from among a group of devices that can reach the destination address of the destination group. And select. For example, in the reachability information 132 shown in FIG. 10B, the devices that can reach the destination addresses d1 and d2 are the devices A and B. Therefore, the device selection unit 121C selects the device A among these devices. Select as the working device. Also, the device B is selected as a spare device. Then, the device selection unit 121C outputs the identification information between the active device and the standby device to the link selection unit 122.

  The routing table creation unit 123C has a routing table 133 (for example, devices A, B, C, and D) indicating a working link and a protection link to a destination group (for example, destination addresses d1 and d2) for each of the start point devices (for example, devices A, B, C, and D) 10 (d)).

  The destination group calculation unit 127 registers (1) a plurality of reachable devices having a plurality of destination addresses in the reachability information 132, and (2) at least a part of the destination address group is the same among the reachable devices. At one time, a destination group that is a set of destination addresses set for each reachable device is obtained. For example, the reachable devices (devices 40) having a plurality of destination addresses on the reachability information 132 in FIG. 10B are devices A and B. Since the destination addresses of the devices A and B are both d1 and d2, the destination group is the destination addresses d1 and d2. The destination group calculation unit 127 outputs the calculated destination group to the device selection unit 121C.

<Processing procedure>
Next, the processing procedure of the routing table creation device 10C will be described with reference to FIGS.

  First, the destination group calculation unit 127 of the routing table creation device 10C of FIG. 11 sets a destination address that can be reached from the same set of devices 40 (devices A and B) among the devices 40 indicated in the reachability information 132. The destination group (destination address d1, d2) is calculated (S41).

  Next, the device selection unit 121C refers to the reachability information 132 and extracts all reachable devices for a certain destination group (S42). For example, on the reachability information 132 in FIG. 10B, since the reachable devices for the destination group (destination addresses d1, d2) are the devices A and B, the devices A and B are extracted.

  Then, the device selection unit 121C selects an active device (for example, device A) and a standby device (for example, device B) from the devices 40 (for example, devices A and B) extracted in S42 (S43).

  Next, similarly to S13 of FIG. 4, the link selection unit 122 selects a working link for reaching the working device and a spare link for reaching the spare device (S44). That is, for each device 40 indicated in the topology information 131 (see FIG. 10C), the link selection unit 122 determines that the device 40 (for example, device C) is the starting device, and the active device ( For example, a working link (for example, link # 2) for reaching device A) is selected. In addition, a backup link (for example, link # 4) for reaching the backup device (for example, device B) from this starting point device is selected. The routing table creation unit 123 sets the working link (for example, link # 2) and the spare link (for example, link # 4) to the destination group (destination address d1, d2) of the selected start point device (for example, device C). And stored in the route table 133 of the starting point device (see the route table 133 of the device C in FIG. 10D).

  After S44, the process is completed for all the devices 40 indicated in the topology information 131 (Yes in S45), and the process is completed for all the destination groups calculated in S41 (Yes in S46). The table creation process ends.

  On the other hand, if there is an unprocessed device 40 among the devices 40 indicated in the topology information 131 (No in S45), the device selection unit 121C performs the processing from S42 on this unprocessed device 40. If there is an unprocessed destination group (No in S46), the device selection unit 121C executes the processing from S41 on for the unprocessed destination group.

  Thus, since the routing table creation device 10C obtains the working link and the protection link for the destination group, it is not necessary to obtain the working link and the protection link for each destination address. Thereby, the processing load for creating the routing table can be reduced.

10, 10A, 10B, 10C Route table creation device 11 Input / output unit 12 Processing unit 13 Storage unit 20 Network information acquisition device 40 Device 121, 121A, 121C Device selection unit 122, 122A, 122B, 122C Link selection unit 123, 123C Route Table creation unit 124 Route table transmission unit 125 Ring search unit 126 Destination address extraction unit 127 Destination group calculation unit 131, 131A Topology information 132 Reachability information 133 Route table

Claims (8)

A routing table creation device that creates a routing table used for packet transfer processing in each device in the network,
For each destination address, the reachability information indicating the identification information of the device of the destination address or the device that can reach the subnetwork, the connection state of each device constituting the network, and the link connecting the devices are shown. An input unit that receives input of topology information and stores it in the storage unit;
For each destination address indicated in the reachability information, a device selection unit that selects a working device and a standby device from a group of devices that can reach the destination address;
For each device indicated in the topology information, when the device is a starting point device, the working path from the starting point device to the working device that can reach the destination address, and the destination device can reach the destination address The spare route to the spare device is calculated, and the topology information is referred to, and the working link that is the link used by the starting device in the working route and the spare link that is the link used in the spare route are selected. A link selector,
For each of the start point devices, for each destination address, a routing table creation unit that creates a routing table showing the working link and the backup link to the destination address;
An output unit that transmits the created route table to each device that is the starting point device. A routing table creation device that creates a routing table used for packet transfer processing in each device in the network,
For each destination address, reachability information indicating identification information of a device at the destination address or a device that can reach the subnetwork, a connection state of each device configuring the network, a link connecting the devices, and the link Is a working link used for the working route, an input unit that receives input of topology information including identification information of a protection link for the link, and stores it in a storage unit;
For each destination address indicated in the reachability information, a device selection unit that selects a working device from a group of devices that can reach the destination address; and
For each of the devices indicated in the topology information, when the device is a starting device, calculate a working path from the starting device to the working device that can reach the destination address, refer to the topology information, and A link selection unit that selects a working link used by the starting point device for the working route, and selects a backup link for the selected working link in the topology information;
For each of the start point devices, for each destination address, a route table creation unit that creates a route table indicating the working link and the backup link to the destination address;
An output unit that transmits the created route table to each device that is the starting point device. A routing table creation device that creates a routing table used for packet transfer processing in each device in the network,
For each destination address, the reachability information indicating the identification information of the device of the destination address or the device that can reach the subnetwork, the connection state of each device constituting the network, and the link connecting the devices are shown. An input unit that receives input of topology information and stores it in the storage unit;
A ring search unit that searches for a group of devices constituting the ring with reference to the topology information until two or more devices reachable to the same destination address indicated in the reachability information are included in any one of the rings; ,
With reference to the reachability information, for each device group that constitutes the ring, a destination address extraction unit that extracts a destination address group in which the device group is an edge node;
Referring to the topology information, for each device in the device group that constitutes the ring, when the device is a starting point device, (1) connected to the device in the first rotation direction in the ring constituted by the device group A link selection unit that selects, as a working link, (2) a link that is connected to a device having a rotation direction opposite to the first rotation direction in the ring as a backup link;
For each of the start point devices, for each destination address indicated in the destination address group, a route table creation unit for creating a route table showing the working link and the backup link to the destination address;
An output unit that transmits the created route table to each device that is the starting point device. A routing table creation device that creates a routing table used for packet transfer processing in each device in the network,
For each destination address, the reachability information indicating the identification information of the device of the destination address or the device that can reach the subnetwork, the connection state of each device constituting the network, and the link connecting the devices are shown. An input unit that receives input of topology information and stores it in the storage unit;
When a plurality of devices having a plurality of the destination addresses are registered in the reachability information and at least a part of the set destination addresses among the devices is the same, a set of destination addresses of the devices A destination group calculator for calculating a destination group;
For each destination address indicated in the reachability information, a device selection unit that selects a working device and a standby device from a group of devices that can reach the destination address;
For each of the devices indicated in the topology information, when the device is a starting point device, the working path from the starting point device to the working device that can reach the destination address, and the destination device can reach the destination address The spare route to the spare device is calculated, and the topology information is referred to, and the working link that is the link used by the starting device in the working route and the spare link that is the link used in the spare route are selected. A link selector,
For each of the start point devices, for each destination address of the calculated destination group, a route table creation unit that creates a route table indicating the working link and the spare link to the destination address of the destination group;
An output unit that transmits the created route table to each device that is the starting point device. The link selection unit
When calculating the working route and the backup route,
5. The route table creation apparatus according to claim 1, wherein a route that minimizes the number of hops or a link cost is calculated with reference to the topology information. The link selection unit
When calculating the working route and the backup route,
5. The route according to claim 1, wherein the working route and the backup route select a route that does not pass through the same device or link with reference to the topology information. The described routing table creation device. The device selector is
4. The route table creation apparatus according to claim 3, wherein when the active device is selected, a device with the smallest number of hops or link cost to the destination address is selected with reference to the topology information. A routing table creation device that creates a routing table used for packet transfer processing in each device in the network,
For each destination address, the reachability information indicating the identification information of the device of the destination address or the device that can reach the subnetwork, the connection state of each device constituting the network, and the link connecting the devices are shown. Receiving input of topology information and storing it in a storage unit;
For each destination address indicated in the reachability information, selecting a working device and a spare device from a group of edge nodes that transfer packets to the destination address; and
For each of the devices indicated in the topology information, when the device is a starting point device, a working route from the starting point device to the working device and a backup route from the starting point device to the spare device are calculated, and the topology Referring to information, selecting a working link that is a link used by the starting point device in the working route and a spare link that is a link used in the backup route;
For each of the start point devices, for each destination address, creating a routing table indicating the working link and the backup link to the destination address;
And a step of transmitting the created routing table to each device as the starting point device.

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