Network control device and network control method

Abstract

In order to perform appropriate IP routing in consideration of information about a transmission layer when a failure has occurred in a network, this network control device controls: a transmission network that is configured from a plurality of transmission devices; and an IP network that connects a plurality of routers by using the transmission network. The network control device comprises: a failure determination unit that determines a failure location on the basis of failure information on the plurality of transmission devices and failure information on the plurality of routers; a transmission path determination unit that determines whether or not switching of a transmission path is necessary for the failure location, and, when the switching of the transmission path is necessary, determines a route for the transmission path after the switching; a transmission device control unit that switches the transmission path for the transmission devices on the basis of the determination result of the transmission path determination unit; an IP routing determination unit that determines whether or not switching of an IP routing is necessary for the failure location and, when the switching of the IP routing is necessary, determines the priority of the IP routing after the switching; and a router control unit that sets the priority of the IP routing for the routers on the basis of the determination result of the IP routing determination unit.

Description

Network control device and network control method

[0001] The present invention relates to a network control device and a network control method.

[0002] In a service provider network that connects IP (Internet Protocol) routers using a transmission network and provides IP connection services, a transfer path for IP packets is determined by IP routing.

[0003] In IP routing, routing information is exchanged between routers using a routing protocol such as OSPF (Open Shortest Path First) or BGP (Border Gateway Protocol), and the information is stored in a routing table (see, for example, Non-Patent Documents 1 and 2). In IP routing, the next hop (next forwarding destination) corresponding to the destination IP address is calculated from the information in the routing table and stored in a forwarding table.

[0004] In addition to IP routing protocols such as OSPF and BGP, service provider networks can also use, for example, MPLS (Multi-Protocol Label Switching) or Segment Routing (see, for example, Non-Patent Documents 3 and 4). Furthermore, by using MPLS or Segment Routing, service provider networks can also provide VPN (Virtual Private Network) services that only provide communications between specific sites (see, for example, Non-Patent Document 5).

[0005] RFC 2328, "OSPF Version 2", [online], April 1998, [Retrieved March 19, 2023], Internet < https: / / www.ietf.org / rfc / rfc2328.txt>. RFC 4271, "A Border Gateway Protocol 4 (BGP-4)", [online], January 2006, [Retrieved March 19, 2023], Internet < https: / / www.ietf.org / rfc / rfc2328.txt>. RFC 3031, "Multiprotocol Label Switching Architecture", [online], January 2001, [Retrieved March 19, 2023], Internet<https: / / www.ietf.org / rfc / rfc3031.txt> RFC 8402, "Segment Routing Architecture", [online], July 2018, [Retrieved March 19, 2023], Internet<https: / / www.ietf.org / rfc / rfc8402.txt> RFC 4364, "BGP / MPLS IP Virtual Private Networks (VPNs)", [online], February 2006, [Retrieved March 19, 2023], Internet<https: / / www.ietf.org / rfc / rfc4364.txt> RFC 4456, "BGP Route Reflection: An Alternative to Full Mesh Internal BGP (IBGP)", [online], April 2006, [Retrieved March 19, 2023], Internet<https: / / www.ietf.org / rfc / rfc4456.txt> .

[0006] Conventional techniques have a problem in that when a failure occurs in a network, it is not possible to perform appropriate IP routing taking into account information on the transmission layer.

[0007] The embodiments of the present invention have been made in view of the above-mentioned problems, and when a failure occurs in a network, it is possible to perform appropriate IP routing by taking into account information on the transmission layer.

[0008] In order to solve the above problems, a network control device according to an embodiment of the present invention is a network control device that controls a transmission network made up of a plurality of transmission devices and an IP network that connects a plurality of routers using the transmission network, and includes: a failure determination unit that determines the location of a failure from failure information of the plurality of transmission devices and failure information of the plurality of routers; a transmission path determination unit that determines whether or not a transmission path needs to be switched for the failure location, and if the transmission path switching is necessary, determines the route of the transmission path after switching; a transmission device control unit that switches the transmission path of the transmission device based on the determination result of the transmission path determination unit; an IP routing determination unit that determines whether or not an IP routing switch is necessary for the failure location, and if the IP routing switching is necessary, determines the priority of the IP routing after switching; and a router control unit that sets the priority of the IP routing of the router based on the determination result of the IP routing determination unit.

[0009] According to an embodiment of the present invention, when a failure occurs in a network, appropriate IP routing can be performed taking into account information at the transport layer.

[0010] FIG. 1 is a diagram illustrating an example of a network configuration according to the present embodiment. FIG. 2 is a diagram illustrating an example of a network control device according to the present embodiment. FIG. 3 is a diagram illustrating an example of information managed by a router management unit according to the present embodiment. FIG. 4 is a diagram illustrating an example of information managed by a transmission management unit according to the present embodiment. FIG. 5 is a sequence diagram illustrating an example of processing when a failure occurs according to Example 1. FIG. 6 is a diagram illustrating an example of a network state before a failure occurs according to the present embodiment. FIG. 7 is a diagram illustrating an example of a network state after a failure occurs according to the present embodiment. FIG. 8 is a diagram illustrating an example of a network configuration according to Example 2. FIG. 9 is a sequence diagram illustrating an example of processing when a failure occurs according to Example 2. FIG. 10 is a diagram illustrating an example of a computer hardware configuration. FIG. 11 is a diagram illustrating an example of a physical configuration of a service provider NW. FIG. 12 is a diagram illustrating an example of an IP network configuration of a service provider NW. FIG. 13 is a diagram illustrating a problem with the conventional technology. FIG. 14 is a diagram illustrating a problem with the conventional technology.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0012] <Network Configuration> Before describing the routing control device according to this embodiment, a service provider network (hereinafter referred to as service provider NW) that is the premise of this embodiment will be described.

[0013] Fig. 11 is a diagram illustrating an example of the physical configuration of a service provider NW. In the example of Fig. 11, the service provider NW1 includes multiple transmission devices 11a to 11f that constitute a transmission network 10, and multiple routers 12a to 12f that use the transmission network 10 to constitute an IP (Internet Protocol) network. In the following description, "transmission device 11" will be used to refer to any one of the multiple transmission devices 11a to 11f. Similarly, "router 12" will be used to refer to any one of the multiple routers 12a to 12f.

[0014] The service provider NW1 is a network that provides IP connection services by connecting between routers 12, which are IP routers, using a transmission network 10. The service provider NW1 determines the transfer path of an IP packet by IP routing.

[0015] In IP routing, routing information is exchanged between routers 12 using a routing protocol such as OSPF (Open Shortest Path First) or BGP (Border Gateway Protocol), and the information is stored in a routing table. In IP routing, the next hop (next forwarding destination) corresponding to the destination IP address is calculated from the information in the routing table, and stored in a forwarding table.

[0016] Furthermore, in the event of a failure in the service provider NW1, route information is re-exchanged using a routing protocol, enabling automatic rerouting to create a new forwarding table.

[0017] The service provider NW1 can use not only IP routing protocols such as OSPF or BGP, but also, for example, MPLS (Multi-Protocol Label Switching) or Segment Routing, etc. Furthermore, by using MPLS or Segment Routing, the service provider network can also provide a VPN (Virtual Private Network) service that provides communication only between specific sites.

[0018] Fig. 12 is a diagram showing an example of an IP network configuration of a service provider NW. This diagram shows the configuration of an IP network in which the transmission network 10 described in Fig. 1d connects routers 12. The transmission network 10 connects the routers 12 via transmission paths. The transmission paths include wavelength paths and / or OTN (Optical Transport Network) paths, etc.

[0019] 12, routers 12a and 12b, routers 12c and 12d, and routers 12e and 12f are each paired and can reach the same address. For example, routers 12a and 12b are connected to a user network (hereinafter referred to as a user NW) 2a whose IP address is address A. Similarly, routers 12c and 12d are connected to a user NW 2b whose IP address is address B, and routers 12e and 12f are connected to a user NW 2c whose IP address is address C.

[0020] In the following description, the term "user NW2" will be used to refer to any of the user networks 2a, 2b, and 2c. In the user NW2, a router of the user NW2 is connected to a router 12 of the service provider NW1, and addresses A, B, and C are reached via the router of the user NW2.

[0021] 13 and 14 are diagrams for explaining the conventional technical problems. Here, it is assumed that the service provider NW1 and the user NW2 exchange route information (e.g., addresses A, B, and C) using eBGP (External BGP). It is also assumed that route information is exchanged between the routers 12 of the service provider NW1 using iBGP (Internal BGP).

[0022] 13, if a failure 21 occurs between transmission device 11a and transmission device 11c, the transmission path connecting router 12a and router 12c and the transmission path connecting router 12a and router 12e will also fail. Therefore, the IP network configuration of service provider NW1 will be as shown in FIG. 14. In this case, the route from address A to address B is recalculated by IP routing, resulting in, for example, first route 31. However, first route 31 is a detour in terms of the physical configuration, and it would be more efficient to select, for example, second route 32.

[0023] As another example, a case can be considered in which the failure 21 can be restored by switching the transmission path. For example, the transmission path between the routers 12a and 12c (the transmission path between the transmission devices 11a and 11c) can be switched to a route of transmission device 11a-transmission device 11b-transmission device 11d-transmission device 11c.

[0024] In this way, when a failure occurs in the service provider NW1, it is desirable to determine whether to perform switching at the transmission device 11 or switching by IP routing. However, in such a case, a timer is generally provided for switching by IP routing to avoid simultaneous switching by both. In this case, if switching by the transmission layer is ultimately not possible (e.g., due to a lack of resources), switching by IP routing is performed, but this poses a problem in that the timer slows down the switching time.

[0025] As described above, in the conventional technology, IP routing does not take into account information on the transmission layer, and therefore has the problem that it is not always possible to select an efficient switching route in the event of a failure.

[0026] In addition, since it does not take into account whether switching is possible at the transmission layer, a timer or the like is set up in the event of a failure to wait whether switching at the transmission layer will be performed before switching using IP routing, which creates the problem that route switching cannot necessarily be performed quickly.

[0027] Therefore, the network according to this embodiment has a system configuration such as that shown in FIG. 1, for example, so that when a failure occurs in the network, appropriate IP routing can be performed taking into account information in the transmission layer.

[0028] <Network Configuration> Fig. 1 shows an example of the configuration of a network according to this embodiment. As shown in Fig. 1, a network 100 according to this embodiment includes a service provider NW1 described in Figs. 11 to 14 and a network control device 110 that is a controller that controls the service provider NW1.

[0029] 1 is an example. Here, the description will be made assuming that the service provider NW1 has the same configuration as the service provider NW1 described in FIGS. 11 to 14. In this embodiment, when a failure occurs in the service provider NW1, the service provider NW1 does not automatically reroute, but instead instructs the network control device 110 to switch IP routing.

[0030] The network control device 110 is, for example, an information processing device having a computer configuration, or a system including multiple computers. The network control device 110 realizes, for example, each functional configuration shown in FIG. 2 by executing a predetermined program on the computer included in the network control device 110.

[0031] Fig. 2 is a diagram showing an example of the configuration of the network control device 110 according to this embodiment. In the example of Fig. 2, the network control device 110 realizes various functional components, such as a router management unit 201, a transmission management unit 202, a device information acquisition unit 203, a router information acquisition unit 204, a failure determination unit 205, a transmission path determination unit 206, an IP routing determination unit 207, a transmission device control unit 208, a router control unit 209, and a storage unit 210. Note that at least a portion of the above functional components may be realized by hardware.

[0032] 3, the router management unit 201 manages information such as router information 301, IP link information 302, and IP routing priority information 303. When the IP routing determination unit 207 determines that IP routing switching should be performed, the router management unit 201 updates the IP routing priority information 303 and sets IP routing priority for each router via the router control unit 209.

[0033] Fig. 3 is a diagram showing an example of information managed by the router management unit according to this embodiment. The router information 301 stores information about groups of routers 12 connected to the same destination. In the example of Fig. 3, the router information 301 includes information such as a group ID and a router ID as items. The group ID is identification information for identifying a group. The router ID is identification information for identifying a router. Here, it is assumed that the router IDs of routers 12a, 12b, ..., 12f are #1, #2, ..., #6, respectively.

[0034] In the example of Figure 3, as shown in Figure 12, routers 12a and 12b are connected to the same address A, so the router IDs "#1" and "#2" of routers 12a and 12b are stored in the same group ID "G1".

[0035] The IP link information 302 stores information about links connecting routers 12. In the example of Fig. 3, the IP link information 302 includes items such as router ID1, router ID2, transmission path ID, and attribute value. Router ID1 is identification information that identifies the first router 12. Router ID2 is identification information that identifies the second router 12. Transmission path ID is identification information that identifies the transmission path between the first router 12 and the second router 12. The attribute value includes information such as cost or bandwidth, for example.

[0036] The IP routing priority information 303 stores the priority between each router 12 in each group. In the example of Fig. 3, the IP routing priority information 303 includes information such as group ID1, group ID2, router ID1, router ID2, and priority. Group ID1 is identification information that identifies the first group. Group ID2 is identification information that identifies the second group. Router ID1 is identification information that identifies the first router 12. Router ID2 is identification information that identifies the second router 12.

[0037] In the example of Figure 3, the IP routing priority information 303 indicates that the router IDs between routers in groups "G1" and "G2" are combinations of #1 and #3, #1 and #4, #2 and #3, and #2 and #4, and that the priorities of each combination are P1, P3, P4, and P2.

[0038] The transmission management unit 202 manages, for example, transmission link information 401 and transmission path information 402 as shown in Fig. 4. Furthermore, when the transmission path determination unit 206 determines that transmission path switching should be performed, the transmission management unit 202 updates the transmission path information 402 and controls the transmission device 11 via the transmission device control unit 208 to switch the transmission path.

[0039] FIG. 4 is a diagram showing an example of information managed by the transmission management unit according to this embodiment. The transmission link information 401 stores link information connecting the transmission devices 11. In the example of FIG. 4, the transmission link information 401 includes information such as a transmission device ID1, a transmission device ID2, and an attribute value. The transmission device ID1 is identification information for identifying the first transmission device 11. The transmission device ID2 is identification information for identifying the second transmission device 11. The attribute value is an attribute value of the link between the first transmission device and the second transmission device. This attribute value includes information such as cost and physical distance. It is assumed here that the transmission device IDs of the transmission devices 11a, 11b, ..., 11f are #1, #2, ..., #6, respectively.

[0040] The transmission path information 402 stores information about the transmission path. In the example of FIG. 4, the transmission path information 402 includes information such as a transmission path ID, an endpoint router ID 1, an endpoint router ID 2, a transmission device route, and attribute values. The transmission path ID is identification information that identifies the transmission path. The endpoint router ID 1 is identification information that identifies the router 12 at one endpoint of the transmission path. The endpoint router ID 2 is identification information that identifies the router 12 at the other endpoint of the transmission path. The transmission device route is the transmission device ID of the transmission device 11 through which the transmission path passes. It is an attribute value of the transmission path. This attribute value includes, for example, information such as bandwidth.

[0041] The device information acquisition unit 203 executes a device information acquisition process to acquire information on each transmission device 11 in the service provider NW 1. For example, the device information acquisition unit 203 acquires information including failure information from each transmission device 11.

[0042] The router information acquisition unit 204 executes a router information acquisition process to acquire information about each router 12 of the service provider NW 1. For example, the router information acquisition unit 204 acquires information including failure information from each router 12.

[0043] The fault determination unit 205 executes a fault determination process to determine the location of the fault from the fault information of multiple transmission devices 11 acquired by the device information acquisition unit 203 and the fault information of multiple routers 12 acquired by the router information acquisition unit 204.

[0044] The transmission path determination unit 206 determines whether or not switching of the transmission path is necessary for the fault location determined by the fault determination unit 205, and if switching of the transmission path is necessary, executes a transmission path determination process to determine (or decide) the route of the transmission path after switching. For example, the transmission path determination unit 206 performs the transmission path determination process based on the transmission link information 401 and the transmission path information 402 managed by the transmission management unit 202.

[0045] The IP routing determination unit 207 determines whether or not IP routing switching is necessary for the failure location determined by the failure determination unit 205, and if IP routing switching is necessary, executes IP routing determination processing to determine (decide) the priority of IP routing after switching. For example, the IP routing determination unit 207 executes IP routing determination processing based on the router information 301, IP link information 302, IP routing priority information 303, etc. managed by the router management unit 201.

[0046] The transmission device control unit 208 executes a transmission device control process to control the transmission device 11. For example, the transmission device control unit 208 controls the transmission device 11 based on the determination result of the transmission path determination unit 206 to switch the transmission path.

[0047] The router control unit 209 executes a router control process for controlling the router 12. For example, the router control unit 209 updates the IP routing priority of the router 12 based on the determination result of the IP routing determination unit 207.

[0048] The storage unit 210 stores various information such as the router information 301, IP link information 302, IP routing priority information 303, transmission link information 401, and transmission path information 402 described above.

[0049] 2 is an example. For example, each functional component of the network control device 110 may be distributed across multiple devices. The functions of the device information acquisition unit 203 and / or the transmission management unit 202 may be provided by the transmission device control unit 208 or the like. Similarly, the functions of the router information acquisition unit 204 and / or the router management unit 201 may be provided by the router control unit 209 or the like. The storage unit 210 may be provided outside the network control device 110.

[0050] <Processing Flow> Next, the processing flow of the network control method according to this embodiment will be described.

[0051] 5 is a sequence diagram illustrating an example of a process performed when a failure occurs according to Example 1. This process illustrates an example of a process executed by the network control device 110 when a failure occurs in the service provider NW1.

[0052] In step S501, the device information acquisition unit 203 of the network control device 110 acquires failure information of the plurality of transmission devices 11a, 11b, . . .

[0053] In step S502, the router information acquisition unit 204 of the network control device 110 acquires failure information of the plurality of routers 12a, 12b, . . .

[0054] In step S503, the failure determination unit 205 of the network control device 110 determines the location of the failure from the failure information of multiple transmission devices 11 acquired by the device information acquisition unit 203 and the failure information of multiple routers 12 acquired by the router information acquisition unit 204.

[0055] For example, assume that a failure 21 occurs in the service provider NW1 as shown in Figure 13. In this case, the router information acquisition unit 204 acquires failure information for the link between the routers 12a and 12c and the link between the routers 12a and 12e. The device information acquisition unit 203 also acquires failure information for the transmission path between the routers 12a and 12c, the transmission path between the routers 12a and 12e, and the link between the transmission devices 11a and 11c. Using this information, the failure determination unit 205 determines, using the IP link information 302, the transmission path information 402, and the transmission link information 401, that the link between the transmission device 11a and 11c has failed, and that as a result, the link between the routers 12a and 12c and the link between the routers 12a and 12e have also failed.

[0056] In step S504, the transmission path determination unit 206 of the network control device 110 determines whether or not to perform transmission switching for the failure location determined by the failure determination unit 205. For example, the transmission path determination unit 206 determines to perform transmission switching if transmission path switching is possible in the transmission layer. If transmission switching is to be performed, the transmission path determination unit 206 determines (or decides) the route of the transmission path after switching and proceeds to step S505. On the other hand, if transmission switching is not to be performed, the transmission path determination unit 206 proceeds to step S506.

[0057] In step S505, the transmission device control unit 208 of the network control device 110 switches the transmission path by controlling the transmission devices 11a, 11b, . . . according to the route of the switched transmission path determined by the transmission path determination unit 206.

[0058] For example, when the transmission path determination unit 206 determines that transmission path switching should be performed, the transmission management unit 202 updates the transmission path information 402 and instructs the transmission device control unit 208 to switch the transmission path. The transmission device control unit 208 controls the transmission device 11 in accordance with the instruction from the transmission management unit 202.

[0059] In step S506, the IP routing determination unit 207 of the network control device 110 determines whether or not to perform IP routing switching for the failure location determined by the failure determination unit 205. If IP routing switching is to be performed, the IP routing determination unit 207 transitions the process to step S507. On the other hand, if IP routing switching is not to be performed, the IP routing determination unit 207 ends the process of FIG. 5.

[0060] In step S507, the router control unit 209 of the network control device 110 switches the IP routing by controlling the routers 12a, 12b, ... in accordance with the IP routing determined by the IP routing determination unit 207. Specifically, the router control unit 209 updates the IP routing priority of the router 12.

[0061] The process of FIG. 5 enables the network control device 110 to take into account information on the transmission layer and perform appropriate IP routing when a failure occurs in the network.

[0062] 5 is an example of the process to be performed when a failure occurs. For example, the network control device 110 may execute the processes of steps S506 and S507 before the processes of steps S504 and S505. The network control device 110 may select a more efficient switch by determining whether to perform transmission switching and whether to perform IP routing switching in combination.

[0063] (IP Routing Determination Process) Here, a specific example of the IP routing determination process executed by the IP routing determination unit 207 will be described.

[0064] 6 is a diagram showing an example of the state of the network before a failure occurs according to this embodiment. This diagram shows an example of the state of the physical configuration of the service provider NW1 according to this embodiment and the IP network configuration before a failure occurs.

[0065] Here, it is assumed that the routers 12a and 12c have the lowest cost among the four router pairs (see IP routing priority information 303), which are combinations of routers 12a and 12b included in group G1 and routers 12c and 12d included in group G2. It is also assumed that the IP routing priority is set so that communication between address A and address B passes through the route from router 12a to router 12c, which has the lowest cost.

[0066] Here, the minimum cost is, for example, the router pair with the smallest sum of the physical distance and / or cost of the transmission path associated with the IP link. In the example of Figure 6, the route of the router pair of router 12a and router 12c uses only the IP link between router 12a and router 12c, and transmission path #A associated with this IP link has the minimum cost compared to the others.

[0067] Furthermore, the IP routing priority is specifically set using BGP attribute values ​​so as to satisfy the following (1) to (4): (1) The priority of the route advertised from router 12a to address A is set higher than the priority of the route advertised from router 12b to address A. (2) The priority of the route advertised from router 12a to router 12c is set higher than the priority of the route advertised from router 12a to router 12d. (3) The priority of the route advertised from router 12c to router 12a is set higher than the priority of the route advertised from router 12c to router 12b. (4) The priority of the route advertised from router 12c to address B is set higher than the priority of the route advertised from router 12d to address B.

[0068] 7 is a diagram showing an example of the state of the network after a failure occurs according to this embodiment, which shows an example of the state of the physical configuration of the service provider NW1 according to this embodiment and the state of the IP network configuration after a failure occurs.

[0069] 7, when a failure 21 occurs in link 601 between transmission devices 11a and 11c, the route for the router pair of router 12a and router 12c becomes the link between router 12a and router 12b, the link between router 12b and router 12d, and the link between router 12d and router 12c, increasing the cost. As a result, the route between router 12b and router 12d has the lowest cost for the router pair of router 12a and router 12c. In this case, the IP routing determination unit 207 calculates the IP routing priority of each router 12 so that communication between address A and address B passes through the router pair of router 12b and router 12d.

[0070] Note that the IP routing priority may be calculated in advance according to the location of the failure, rather than after a failure occurs. In this case, the IP routing determination unit 207 stores the results of the calculation in advance in the storage unit 210, etc., and when a failure occurs, obtains the calculation results of the IP routing priority according to the location of the failure from the storage unit 210, etc.

[0071] Furthermore, the router pair with the lowest cost may be calculated using not only the cost between the router pair but also the cost between address A and address B. In this case, it is necessary to know the cost of the link between the service provider N1 and user NW2 (for example, the link between router 12a and address A).

[0072] Furthermore, the IP routing determination process may be triggered not only by the occurrence of a failure, but also by failure prediction before a failure actually occurs. For example, the network control device 110 may have a failure information determination unit and predict failure information from performance degradation information that leads to failure prediction. Furthermore, the IP routing determination process may be triggered by planned construction (for example, a maintenance worker specifying the scheduled date and time of construction and the location of the failure).

[0073] [Example 2] Fig. 8 is a diagram illustrating an example of the configuration of the network 100 according to Example 2. As illustrated in Fig. 8, the network 100 according to Example 2 includes a BGP-RR (Route Reflector) 801 in addition to the configuration of the network 100 described in Fig. 1.

[0074] In the first embodiment, the network control device 110 sets IP routing priorities to satisfy the following (1) to (4) when switching IP routing: (1) The priority of the route advertised from the router 12a to address A is set higher than the priority of the route advertised from the router 12b to address A. (2) The priority of the route advertised from the router 12a to the router 12c is set higher than the priority of the route advertised from the router 12a to the router 12d. (3) The priority of the route advertised from the router 12c to the router 12a is set higher than the priority of the route advertised from the router 12c to the router 12b. (4) The priority of the route advertised from the router 12c to address B is set higher than the priority of the route advertised from the router 12d to address B.

[0075] Here, in order not to notify users of a failure within the service provider NW1, it is also possible to implement only (2) and (3) and not (1) and (4). In this case, communication from address A to address B continues to use router 12a, with the router pair of routers 12a and 12d having the lowest cost, and communication from address B to address A continues to use router 12c, with the router pair of routers 12b and 12c having the lowest cost. The network control device 110 also sets IP routing priorities to ensure the above routes.

[0076] In such a case, when BGP uses BGP-RR 801, the network control device 110 may set the IP routing priority only to BGP-RR 801, rather than to each router 12. In this method, the network control device 110 sets the IP routing priority to one BGP-RR 801, rather than to multiple routers 12, making control easier.

[0077] 8, for example, BGP-RR 801 sets an iBGP peer for each router 12. In addition, the network control device 110 sets an IP routing priority for BGP-RR 801. The IP routing priority set in BGP-RR 801 is advertised to each router 12 via iBGP.

[0078] The BGP-RR 801 may be implemented by any one of the routers 12a to 12d, or may be an independent device. The function of the BGP-RR 801 may also be provided by the network control device 110.

[0079] <Processing Flow> Fig. 9 is a sequence diagram showing an example of processing when a failure occurs according to Example 2. Note that, among the processing in Fig. 9, the processing in steps S501 to S505 is the same as the processing when a failure occurs according to Example 1 described in Fig. 5, and therefore description thereof will be omitted here.

[0080] In step S901, the IP routing determination unit 207 of the network control device 110 determines whether or not to perform IP routing switching for the failure location determined by the failure determination unit 205. If IP routing switching is to be performed, the IP routing determination unit 207 transitions the process to step S902. On the other hand, if IP routing switching is not to be performed, the IP routing determination unit 207 ends the process of FIG.

[0081] In step S902, the router control unit 209 of the network control device 110 switches IP routing by controlling the BGP-RR 801 in accordance with the IP routing determined by the IP routing determination unit 207 (updating the IP routing priority of the router 12). In this way, the router control unit 209 may control multiple routers 12a, 12b, ... via other devices such as the BGP-RR 801.

[0082] The process of FIG. 9 allows the network control device 110 to easily perform appropriate IP routing in consideration of information on the transmission layer when a failure occurs in the network.

[0083] <Hardware Configuration> The network control device 110 has, for example, the hardware configuration of a computer 1000 as shown in Fig. 10. Alternatively, the network control device 110 is realized by a plurality of computers 1000.

[0084] 10 is a diagram showing the hardware configuration of a computer according to this embodiment. In the example of Fig. 10, a computer 1000 includes a processor 1001, a memory 1002, a storage device 1003, a communication device 1004, an input device 1005, an output device 1006, and a bus B.

[0085] The processor 1001 is, for example, an arithmetic unit such as a CPU (Central Processing Unit) that executes predetermined programs to realize various functions. The memory 1002 is a storage medium readable by the computer 1000 and includes, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory). The storage device 1003 is a computer-readable storage medium and may include, for example, a HDD (Hard Disk Drive), an SSD (Solid State Drive), various optical disks, and magneto-optical disks.

[0086] The communication device 1004 includes one or more pieces of hardware (communication devices) for communicating with other devices via a wireless or wired network. The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside.

[0087] The bus B is commonly connected to the above components and transmits, for example, address signals, data signals, and various control signals. The processor 1001 is not limited to a CPU, and may be, for example, a DSP (Digital Signal Processor), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0088] (Supplementary Note) The network control device 110 in this embodiment is not limited to being realized by a dedicated device, but may also be realized by a general-purpose computer. In this case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize the function. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0089] Furthermore, "computer-readable recording media" includes various storage devices such as portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as hard disks built into computer systems. Furthermore, "computer-readable recording media" may also include devices that dynamically store programs for a short period of time, such as communication lines when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and devices that store programs for a certain period of time, such as volatile memory within computer systems that serve as servers or clients in such cases.

[0090] Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in a computer system, or may be one that is realized using hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

[0091] <Effects of the embodiment> According to the network control device 110 of the present embodiment, when a failure occurs in the network, it becomes possible to perform appropriate IP routing in consideration of information on the transmission layer.

[0092] Furthermore, the network control device 110 controls IP routing taking into account information on the transmission layer, making it possible to select an efficient switching route in the event of a failure.

[0093] Furthermore, the network control device 110 can quickly determine whether switching is necessary at the IP layer by considering whether switching is possible at the transmission layer, thereby realizing high-speed route switching.

[0094] Summary of Embodiments This specification discloses at least the following network control device, network control method, and program: (Item 1) A network control device that controls a transmission network made up of a plurality of transmission devices and an IP network that connects a plurality of routers using the transmission network, comprising: a failure determination unit that determines a failure location based on failure information of the plurality of transmission devices and failure information of the plurality of routers, a transmission path determination unit that determines whether or not a transmission path needs to be switched for the failure location and, if the transmission path switching is necessary, determines a route for the transmission path after the switching, a transmission device control unit that switches the transmission path of the transmission device based on the determination result of the transmission path determination unit, an IP routing determination unit that determines whether or not an IP routing switch is necessary for the failure location and, if the IP routing switching is necessary, determines a priority of the IP routing after the switching, and a router control unit that sets the priority of the IP routing of the router based on the determination result of the IP routing determination unit. (Clause 2) The network control device according to Clause 1, comprising an information management unit that manages IP network information including information on groups of routers connected to the same destination, information on the transmission paths connecting the routers, and information on the IP routing priority indicating the priority between each router in the groups, wherein the IP routing determination unit determines the priority of the IP routing after the switch based on the IP network information when the IP routing needs to be switched. (Clause 3) The network control device according to Clause 1 or 2, wherein the IP routing determination unit calculates a router pair with the smallest cost in accordance with the failure location when the IP routing needs to be switched, and determines the priority of the IP routing to pass through the calculated router pair.(Clause 4) A network control method in which a network control device that controls a transmission network made up of a plurality of transmission devices and an IP network connecting a plurality of routers using said transmission network executes: a failure determination process that determines a failure location from failure information of said plurality of transmission devices and failure information of said plurality of routers, a transmission path determination process that determines whether or not a transmission path needs to be switched for said failure location, and if the transmission path switching is necessary, determines a route for the transmission path after switching, a transmission device control process that switches the transmission path of said transmission device based on the determination result of the transmission path determination process, an IP routing determination process that determines whether or not an IP routing switch is necessary for said failure location, and if the IP routing switching is necessary, determines the priority of the IP routing after switching, and a router control process that sets the priority of the IP routing of said router based on the determination result of the IP routing determination process. (Clause 5) A program, or a storage medium that stores a program, that causes a computer to execute the network control method described in clause 4.

[0095] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0096] REFERENCE SIGNS LIST 1 Service provider NW 10 Transmission network 11, 11a, 11b, ... Transmission device 12, 12a, 12b, ... Router 110 Network control device 201 Router management unit 202 Transmission management unit 205 Failure determination unit 206 Transmission path determination unit 207 IP routing determination unit 208 Transmission device control unit 209 Router control unit 301 Router information (information on router groups) 302 IP link information (information on transmission paths connecting routers) 303 IP routing priority information (information on IP routing priority) 1000 Computer

Claims

1. A network control device that controls a transmission network made up of multiple transmission devices and an IP network that connects multiple routers using said transmission network, comprising: a failure determination unit that determines the location of a failure based on failure information of said multiple transmission devices and failure information of said multiple routers; a transmission path determination unit that determines whether or not a transmission path needs to be switched for said failure location, and if the transmission path switching is necessary, determines the route of the transmission path after switching; a transmission device control unit that switches the transmission path of said transmission device based on the determination result of said transmission path determination unit; an IP routing determination unit that determines whether or not an IP routing switch is necessary for said failure location, and if the IP routing switching is necessary, determines the priority of the IP routing after switching; and a router control unit that sets the priority of the IP routing of said router based on the determination result of said IP routing determination unit.

2. A network control device as described in claim 1, further comprising a router management unit that manages information on groups of routers connected to the same destination, information on the transmission paths connecting the routers, and information on the IP routing priority indicating the priority between each router in the group, and wherein when switching of the IP routing is necessary, the IP routing determination unit determines the priority of the IP routing after the switch based on the information managed by the router management unit.

3. A network control device according to claim 1 or 2, wherein the IP routing determination unit, when switching of the IP routing is necessary, calculates a router pair with the smallest cost depending on the failure location, and determines the priority of the IP routing so that the calculated router pair is passed through.

4. A network control method in which a network control device that controls a transmission network composed of multiple transmission devices and an IP network that connects multiple routers using said transmission network executes the following: a failure determination process that determines the location of a failure from failure information of said multiple transmission devices and failure information of said multiple routers; a transmission path determination process that determines whether or not a transmission path needs to be switched for said failure location, and if the transmission path switching is necessary, determines the route of the transmission path after switching; a transmission device control process that switches the transmission path of said transmission device based on the determination result of said transmission path determination process; an IP routing determination process that determines whether or not an IP routing switch is necessary for said failure location, and if the IP routing switching is necessary, determines the priority of the IP routing after switching; and a router control process that sets the priority of the IP routing of said router based on the determination result of said IP routing determination process.

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