JP2008182676A - Autonomous network, node device, network redundancy method and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autonomous network in which communication can be restored in a short period of time. <P>SOLUTION: In an autonomous network, one and the same routing protocol is employed in the network. An additional network (B) which is an autonomous system dedicated to backup routes is added to an existing network (A) which is an existing autonomous system, to thereby provide redundancy to the autonomous network. Part of traffic on the existing network (A) is transmitted by use of the additional network (B). Therefore, at occurrence of failure, communication can be restored in a short period of time in the autonomous network. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an autonomous network, a node device, a network redundancy method, and a network redundancy program, and more particularly to an autonomous network, a node device, a network redundancy method, and a network redundancy program that can cope with occurrence of a network failure. It is.

  Now that the Internet is being developed as a social infrastructure, improving its reliability, especially quick recovery in the event of a network failure, is an extremely important issue. For this reason, various countermeasures have been proposed for transmission line failures (such as optical fiber cuts) and node failures (router and switch failures).

  As a general coping method, redundancy of devices and transmission paths can be mentioned as a simple, quick and reliable method. Specific examples of redundancy include global standard SDH (Synchronous Digital Hierarchy) / SONET (Synchronous Optical NETwork) APS (Automatic Protection Switching), Ethernet (registered trademark) Link Aggregation, etc. ITU-T standard G.841, IEEE802.3ad). Examples of device redundancy include duplexing of a main signal unit and a control unit.

  However, since redundancy increases the scale and cost of the device and network, it is not practical to make everything redundant. In addition, the Internet is originally an aggregate of a large number of networks, and is based on a mesh topology, and thus inherently has redundancy as a network.

  For this reason, as a coping method when a failure occurs, the cost merit is larger when the route of the packet is changed to bypass the failed portion. However, in order to perform the above method, it is necessary to recalculate the route based on the failure information at the node and set a new route.

  The Internet is composed of a number of autonomous systems connected to each other. Each autonomous system is basically managed and operated by one organization, and uses the same routing protocol inside the network. A configuration example of an existing autonomous network is shown in FIG.

  Typical interior gateway protocols (IGPs) include Routing Information Protocol (RIP), Open Shortest Path First (OSPF) (RFC2328), and Intermediate System to Intermediate system (IS-IS). Yes, it is widely used worldwide.

  These are called link state type routing protocols, and a route is set in the following manner. First, a weight called a cost is manually set in advance for links entering and exiting each node. In general, the cost is often set to be inversely proportional to the transmission capacity of the link.

  Next, each node periodically floods (broadcasts) the state and cost of the link connected to each node. As a result, all nodes share network topology information. Each node determines a route to each node so that the route cost is minimized. For this route calculation, a calculation method called Dijkstra's algorithm is mainly used.

  The result of the path calculation is a set of links called a tree (shortest path tree or spanning tree). A tree is a set of minimum links that connect all nodes. Each node updates the routing table based on the information of this tree, and further updates the forwarding table. In many cases, the routing table is stored in the control unit and the forwarding table is stored in each interface unit.

  The above-described information collection and notification, route calculation, and setting thereof are normally processed periodically by software.

  15 to 17 are diagrams showing a state of routing in the existing network. FIG. 15 shows a state with no failure, and the path is indicated by an arrow. FIG. 16 shows a state in which a failure has occurred in the link and a detour route has been formed by routing, and FIG. 17 shows a state in which a failure has occurred in the node and a detour route has been formed by routing.

  The processing flow of the existing routing protocol is shown in FIG. In the existing routing protocol, fixed-cycle timer activation (S11), own node link status acquisition (S12), link status notification (flooding) (S13), other node link status acquisition (S14), tree calculation (S15), routing table update (S16) The processing of updating the forwarding table (S17) is repeated every time the fixed-cycle timer times out.

  The time required for updating the route varies depending on the set cycle, but is usually several seconds to several hundred seconds. The processing flow shown in FIG. 18 shows the processing in a simplified manner. In practice, the above-described notification and route recalculation are performed even when there is a failure or a change in topology.

  Technical documents related to the present invention are described below.

S. Rai et al. “IP Resilience within an Autonomous System: Current Approaches, Challenges, and Future Directions” (IEEE Communications Magazine October 2005 p142-149) C, Alaettinoglu et al. “Towards Millisecond IGP Convergence” (IETF Internet Draft 2000) S. Lee et al. “Proactive vs Reactive Approach to Failure Resilient Routing” (Proc. INFOCOM, Mar. 2004) S. Vellanki et al “Improving Service Availability During Link Failure Transients through Alternate Routing” (Texas A & M Univ., Tech. Rep. TAMUECE-2003-02, Feb. 2003)

  In addition, in the existing routing protocol described above, in order to avoid flooding the control information and applying a load on the network, a minimum flooding interval is set, and during that time, even if a failure is detected, notification cannot be made. Yes. In OSPF, this minimum interval is 5 seconds. In the processing flow shown in FIG. 18, periodic processing is performed by a fixed-cycle timer including the meaning of the minimum flooding interval.

  In the existing routing protocol, if the fixed period timer is set short, the recovery time at the time of failure is shortened, but flooding of control information is frequently performed. This places a load on the network and puts pressure on the transfer of the main signal packet. The fixed-cycle timer is set in consideration of the trade-off between the two. If a failure occurs at a certain location, the packet passing through the failure location is discarded and signal disconnection continues until the next route update. Non-Patent Document 1 proposes a method for shortening the signal interruption time as much as possible.

  In addition, the method proposed in Non-Patent Document 2 shortens the route update cycle and performs quick route recalculation. However, as described above, since flooding of information is frequently performed, an excessive load is applied to the network. In addition, since the route is recalculated for all nodes even in the case of a local failure, the burden of software on the node also increases.

  In addition, the methods proposed in Non-Patent Documents 3 and 4 are methods for preliminarily calculating a backup path in preparation for occurrence of a failure. However, in order to cope with all failures, the amount of calculation increases and it is difficult to realize. Furthermore, no effective countermeasures have been proposed so far that can deal with multiple failures in the network.

  The present invention has been made in view of the above circumstances, and provides an autonomous network, a node device, a network redundancy method, and a network redundancy program capable of realizing rapid recovery of communication, which are the problems described above. The purpose is to provide.

In order to achieve this object, the present invention has the following features.
<Autonomous network>
The autonomous network according to the present invention is:
An autonomous network that uses the same routing protocol inside the network,
Adding an additional network, which is an autonomous system dedicated to a backup route, to an existing network, which is an existing autonomous system, to make it redundant, and transmitting a part of the traffic of the existing network using the additional network. Features.

<Node equipment>
The node device according to the present invention is
A node device that constitutes an autonomous network that uses the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
The node device in the existing network is:
The network is switched to the additional network, and a part of the traffic of the existing network is transmitted using the additional network.

<Network redundancy method>
The network redundancy method according to the present invention includes:
A network redundancy method performed in an autonomous network using the same routing protocol inside the network,
Adding an additional network, which is an autonomous system dedicated to a backup route, to an existing network, which is an existing autonomous system, to make it redundant, and transmitting a part of the traffic of the existing network using the additional network. Features.

The network redundancy method according to the present invention includes:
A network redundancy method performed in an autonomous network using the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
The node device in the existing network is:
Switching to the additional network and performing a step of transmitting a part of the traffic of the existing network using the additional network.

<Network redundancy program>
Further, the network redundancy program according to the present invention is:
A network redundancy program to be executed in an autonomous network that uses the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
Switching to the additional network and causing a node device in the existing network to execute a process of transmitting a part of the traffic of the existing network using the additional network.

  According to the present invention, it is possible to realize quick recovery of communication.

  First, an outline of the autonomous network of the present embodiment will be described with reference to FIG.

  The autonomous network in the present embodiment is an autonomous network that uses the same routing protocol inside the network. In addition, the autonomous network of this embodiment is made redundant by adding an additional network (B) that is an autonomous system dedicated to a backup route to an existing network (A) that is an existing autonomous system. ) Is transmitted using the additional network (B).

  Thereby, since the autonomous network in this embodiment will transmit a part of traffic of the existing network (A) using an additional network (B), it can implement | achieve quick recovery of communication. It becomes possible. Hereinafter, the autonomous network of the present embodiment will be described in detail with reference to the accompanying drawings.

<Configuration of autonomous network>
First, the autonomous network of this embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an autonomous network according to the present embodiment.

  The autonomous network in the present embodiment is configured by adding an autonomous network (additional network) dedicated to the backup route to the existing autonomous network (existing network). An existing routing protocol can be applied as the routing protocol in the autonomous network of the present embodiment, and for example, RIP, OSPF, IS-IS, etc. can be applied.

  In FIG. 1, A indicates an existing network, and B indicates an additional network. The node devices in the existing network A are grouped together in geographically close groups, and C indicates the group. One node device in the additional network B is allocated to each group C, and the node device in the existing network A and the node device in the additional network B are connected.

  In the autonomous network of this embodiment, a node device is newly installed for the additional network B. Then, an interface card is added to each node device in the existing network A, and the node device in the existing network A and the node device in the additional network B are connected.

  Each node device in the additional network B is connected on the mesh and constitutes one autonomous system independent of the existing network A. The additional network B is used exclusively for the backup route of the existing network A, and the bandwidth of the link and the transfer capability of the node are suppressed as much as possible as compared with the existing network A, and the additional network B is constructed on a small scale and economically.

  The autonomous network of the present embodiment is implemented by building the configuration shown in FIG. 1 and mounting software for controlling redundancy switching on each node device in the existing network A.

<Configuration of node device>
Next, the configuration of the node device of this embodiment will be described with reference to FIG. FIG. 2 is a diagram showing a mounting position of software installed in the node device of the present embodiment.

  The node device according to the present embodiment includes a control unit 1 and a main signal unit 2. The control unit 1 includes control unit software 11 and control unit hardware 12. The main signal unit 2 includes a common unit (switch) 21 and interface units 22 and 23.

  The control unit software 11 of the control unit 1 includes an OS (Operating System) (including a communication protocol) 110 and application software 111. The application software 111 includes switching control software 112, a routing table 113, and a routing protocol 114.

  The interface units 22 and 23 of the main signal unit 2 include forwarding tables 221 and 231 and failure detection units 222 and 232.

  The switching control software 112 according to the present embodiment refers to the failure state, the routing table 113, the forwarding tables 221, 231, and the rewriting.

<Outline of operation in autonomous network>
Next, the operation of the autonomous network in the present embodiment will be described with reference to FIGS. 3 to 7 are diagrams illustrating a first operation overview in the autonomous network according to the present embodiment, FIGS. 8 to 12 are diagrams illustrating a second operation overview, and FIG. 13 is a diagram illustrating the present operation. It is a state transition diagram showing the operation of the form of software.

  FIG. 3 shows a normal state in which there is no failure in the existing network A. In this case, the routing protocol operates independently for the existing network A and the additional network B. Note that the routing information is not exchanged between the existing network A and the additional network B, but each node device of the additional network B is routed including the address of the subordinate (the node device of the existing network A). Exchange information.

  Note that the route from the node NS to the node ND is calculated based on information exchanged by the existing routing protocol. Thereby, the route of the arrow shown in FIG. 3 is set. FIG. 4 shows the operation when a failure occurs in the link on the way in the path state shown in FIG.

  As shown in FIG. 4, when the link L1 from the node N1 to the node N6 is broken, the node N1 sends an alarm transfer from the opposite node N6 [alarm transfer in the N6 → N1 direction: for example, RDI of SDH / SONET (Remote Detect Indication etc.) ”immediately detects the failure and transfers the packet destined for the node N6 to the node N2 of the additional network B.

  The node N2 transfers the packet received from the node N1 toward the node N3 in the additional network B. The node N3 transfers the received packet to the node ND of the existing network A. As described above, in the autonomous network according to the present embodiment, when a failure occurs on a link in the middle of the existing network A, the node N1 that detects the failure switches the route and transfers the packet to the additional network B. The packet is transferred through the network B to the node ND which is the final destination.

  The existing network A uses a routing protocol and calculates a route for avoiding the link L1. However, since a certain time is required for the calculation, the packet is transferred via the additional network B during that time.

  The route is recalculated in the existing network A, and when the packet transfer to the node ND becomes possible again, the packet transferred to the additional network B is switched back to the route in the existing network A again. Node N1 performs this path switchback. FIG. 5 shows a state where the route is switched back to the existing network A again. In FIG. 5, the new path | route which avoids the link L1 which is a failure location is shown by the arrow.

  FIG. 6 shows the operation when the link failure is recovered after switching the path. In this case, the node N1 that has detected the failure recovery switches to the additional network B again. This is because the routing is recalculated in the existing network A and the route becomes unstable, so that the packet is transferred via the additional network B which is a backup network while the calculation is converged and the route is fixed. is there.

  After routing convergence, the node N1 switches back from the additional network B to the existing network A. This state is shown in FIG. The reason why the additional network B → the existing network A is switched back after the route in the existing network A is determined is to prepare for the occurrence of a failure in the existing network A by leaving the additional network B as a spare as free as possible. . However, switching and switching are performed with a certain protection time so that switching and switching vibrations do not occur between the existing network A and the additional network B due to intermittent failures.

  8 to 12 show a switching operation and a switching operation when a failure occurs in the node N2 on the path from the node NS to the node ND in the existing network A. FIG. FIG. 8 shows a normal state in which there is no failure in the existing network A. FIG. 9 shows a state where a failure has occurred in the node N2. FIG. 9 shows a state in which the additional network B is used, the packet is transferred from the node N4 to the node N5 in the additional network B, and the packet is transferred to the node ND. FIG. 10 shows a state in which a reroute is constructed in the existing network A. FIG. 10 shows a state in which the packet is transferred from the node N4 to the node in the existing network A without using the additional network B, and the packet is transferred to the node ND. FIG. 11 shows a state immediately after the node N2 is restored. FIG. 11 shows a state in which the additional network B is used, the packet is transferred from the node N4 to the node N5 in the additional network B, and the packet is transferred to the node ND. FIG. 12 shows a state in which a predetermined time has elapsed since the node N2 was restored. FIG. 12 shows a state in which the packet is transferred from the node N4 to the restored node N2 without using the additional network B and is transferred to the node ND. Note that the node N4 performs switching and switching between the existing network A and the additional network B described above.

  In the autonomous network of the present embodiment, in order to perform the switching and switchback described above, each node of the existing network A is equipped with switching control software. The switching control software overwrites the table in which the routing result (next transfer destination) is written in accordance with the failure information and the routing information, and changes the transfer destination, thereby executing the above switching and switching back. The table corresponds to the forwarding tables 221 and 231 shown in FIG. Usually, the table is mounted on the interface card (interface units 22 and 23). A state transition diagram of the switching control software is shown in FIG.

  Each node of the additional network B operates a routing protocol including the nodes of the existing network A under its control. When OSPF is used as a routing protocol, each node performs hierarchical routing by associating each group C of the existing network A with an OSPF area. As a result, the routing table of the additional network B can be compressed.

  As described above, the additional network B configuring the autonomous network of the present embodiment is installed to temporarily transmit a part of traffic when a failure or failure recovery occurs in the existing network A. For this reason, the additional network B does not require a large transfer capability. Therefore, the additional network B can be configured at a low cost with the minimum necessary devices and transmission paths.

  Next, a processing flow of the switching control software 112 installed in each node device will be described with reference to FIG. The switching control software 112 installed in each node device operates at a fixed cycle, and has failure information notified from the physical layer or data link layer, or new transfer destination information notified from the route control unit (routing engine). Based on the above, the forwarding tables 221 and 231 are overwritten, and the packet transfer destination is switched and switched back.

  Note that switching and failback are executed with a certain protection time secured. In addition, the routing fluctuation / convergence determination is performed on the condition that the fluctuation of the routing table 113 is monitored and the fluctuation is continued and stopped for a certain time.

  The state “S1: No failure, no switching” in FIG. 13 corresponds to FIGS. The state “S1: no failure, no switching” → the state “S2: failure, switching” corresponds to FIGS. 4 and 9. Further, the state “S2: failure present, switching” → state “S3: failure present, no switching” corresponds to FIG. 5 and FIG. Further, the state “S3: There is a failure and no switching” → the state “S4: There is no failure and switching” corresponds to FIGS. Further, the state “S4: no failure, switching” → the state “S1: no failure, no switching” corresponds to FIG. 7 and FIG.

  As described above, in the autonomous network according to the present embodiment, a small additional network B for preliminary transfer is added to the existing network A, thereby realizing network redundancy economically. When a failure occurs, the network can be switched from the existing network A to the additional network B to restore communication.

  Further, in the autonomous network according to the present embodiment, it is possible to improve the reliability in proportion to the investment cost of the device and the transmission path by expanding the scale and transfer capability of the additional network B. Furthermore, since the existing routing protocol is used in the autonomous network in this embodiment, migration from the existing network A can be facilitated.

  In addition, in the autonomous network of the said embodiment, although the additional network B was made into mesh shape, the additional network B can also be made into a ring shape or a bus shape.

  In addition, in the autonomous network according to the present embodiment, not only a failure in the existing network A but also a manual or switching to the additional network B when it is necessary to bypass traffic for maintenance or replacement of devices and transmission paths. It is also possible to perform.

  Furthermore, in the autonomous network of the present embodiment, the additional network B can be used to avoid congestion and realize QoS (Quality Of Service). In that case, a path switching policy can be set, and the switching control software 112 is configured to automatically execute path switching according to the situation.

  Further, in the autonomous network of the above embodiment, the interface connection between the existing network A and the additional network B is 1: 1, but the line concentrator between the existing network A and the additional network B. It is also possible to reduce the number of interfaces on the additional network B side. Further, the switching control software 112 of the present embodiment can be realized by a hardware state machine.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone. Those skilled in the art will not be able to deviate from the gist of the present invention. It is possible to construct a form in which various changes are made by making corrections and substitutions.

  For example, the control operation in each device configuring the autonomous network in the present embodiment described above can be executed using hardware, software, or a combined configuration of both.

  In the case of executing processing using software, it is possible to install and execute a program in which a processing sequence is recorded in a memory in a computer incorporated in dedicated hardware. Alternatively, the program can be installed and executed on a general-purpose computer capable of executing various processes.

  For example, the program can be recorded in advance on a hard disk or a ROM (Read Only Memory) as a recording medium. Alternatively, the program can be stored (recorded) temporarily or permanently in a removable recording medium. Such a removable recording medium can be provided as so-called package software. In addition, examples of the removable recording medium include a floppy (registered trademark) disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, and a semiconductor memory.

  The program is installed in the computer from the removable recording medium as described above. In addition, it is wirelessly transferred from the download site to the computer. In addition, it is transferred to the computer via a network by wire.

In addition, the autonomous network in the present embodiment is not only executed in time series according to the processing operation described in the above embodiment, but also the processing capability of the apparatus that executes the process, or in parallel as necessary. It can also be constructed to run individually.
From the above description of the embodiment, the present invention has the following features.

The autonomous network in the present embodiment is an autonomous network in which the same routing protocol is used inside the network,
An existing network which is an existing autonomous system is made redundant by adding an additional network which is provided independently of the existing network and is an autonomous system dedicated to a backup route, and among the node devices and transmission paths in the existing network When a failure occurs in at least one of these, a part of the traffic of the existing network is temporarily transmitted through the additional network.

Further, the node device in the present embodiment is a node device constituting an existing network that is an existing autonomous system in which the same routing protocol is used inside the network,
An autonomous system dedicated to a backup route in which a part of the traffic on the transmission path to the own apparatus is provided independently of the existing network when a failure occurs in at least one of the own apparatus and the transmission path to the own apparatus Switching control software for controlling switching to the additional network for temporary transmission in the additional network.

Further, the network redundancy method in the present embodiment is a network redundancy method used for an autonomous network in which the same routing protocol is used inside the network,
An existing network which is an existing autonomous system is made redundant by adding an additional network which is provided independently of the existing network and is an autonomous system dedicated to a backup route, and among the node devices and transmission paths in the existing network When a failure occurs in at least one of these, a part of the traffic of the existing network is temporarily transmitted through the additional network.

  That is, the autonomous network of the present embodiment combines the redundancy and the route change with respect to the failure of the node or link in the autonomous system in which the same routing protocol is used in the network, thereby It is characterized by economically realizing quick recovery of communication in the event of a failure.

  In addition, the autonomous network of the present embodiment is configured by adding an autonomous network dedicated to a backup route (additional network) to the existing autonomous network (existing network), and the node device of the existing network is geographically Close ones are collectively divided into several groups, one node device of an additional network is assigned to each group, and a plurality of node devices of corresponding existing networks are connected.

  More specifically, in the autonomous network of the present embodiment, a node device is newly installed for an additional network, an interface card is added to each node device of the existing network, and both are connected. Each node device of the additional network is connected on the mesh and constitutes one autonomous system independent of the existing network.

  The additional network is used exclusively for the backup route of the existing network, and the bandwidth of the link and the transfer capability of the node device are kept as low as possible as compared with the existing network, and the small network is constructed economically.

  The additional network is installed to temporarily carry a part of traffic when a failure or failure recovery occurs in the existing network, and does not require a large transfer capability. For this reason, the additional network is configured at a low cost with the minimum necessary devices and transmission paths.

  In addition, the autonomous network of the present embodiment is realized by installing switching control software for controlling redundant switching in each node device of the existing network.

  As a result, in the autonomous network of this embodiment, by adding a small additional network for preliminary transfer to the existing network, network redundancy can be realized economically, and communication can be performed by quick switching when a failure occurs. It can be restored.

  Further, in the autonomous network of the present embodiment, it is possible to improve the reliability in proportion to the investment cost for the device and the transmission path by expanding the scale and transfer capability of the additional network to be added. Furthermore, since the existing routing protocol is operated as it is in the autonomous network of the present embodiment, there is an advantage that migration from the existing network is easy.

It is a block diagram which shows the structural example of the autonomous system network of this embodiment. It is a block diagram which shows the mounting position of the software in the node apparatus of this embodiment. It is a 1st figure which shows the 1st operation | movement outline | summary in the autonomous network of this embodiment. It is a 2nd figure which shows the 1st operation | movement outline | summary of this embodiment. It is a 3rd figure which shows the 1st operation | movement outline | summary of this embodiment. It is a 4th figure which shows the 1st operation | movement outline | summary of this embodiment. It is a 5th figure which shows the 1st operation | movement outline | summary of this embodiment. It is a 1st figure which shows the 2nd operation | movement outline | summary in the autonomous network of this embodiment. It is a 2nd figure which shows the 2nd operation | movement outline | summary of this embodiment. It is a 3rd figure which shows the 2nd operation | movement outline | summary of this embodiment. It is a 4th figure which shows the 2nd operation | movement outline | summary of this embodiment. It is a 5th figure which shows the 2nd operation | movement outline | summary of this embodiment. It is a state transition diagram showing an operation example of software of the present embodiment. It is a figure which shows the structural example of the existing autonomous network. It is a figure which shows the example of routing in the existing network. It is a figure which shows the example of routing in the existing network. It is a figure which shows the example of routing in the existing network. It is a flowchart which shows the process of the existing routing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 Main signal part 11 Control part software 12 Control part hardware 21 Common part (switch)
22, 23 Interface unit 110 OS (including communication protocol)
111 Application software 112 Switching control software 113 Routing table 114 Routing protocol 221 231 Forwarding table 222 232 Fault detection unit A Existing network B Additional network C group N1, N6, NS, ND node L1 link

Claims (19)

An autonomous network that uses the same routing protocol inside the network,
Adding an additional network, which is an autonomous system dedicated to a backup route, to an existing network, which is an existing autonomous system, to make it redundant, and transmitting a part of the traffic of the existing network using the additional network. A featured autonomous network.   The autonomous network according to claim 1, wherein when a failure occurs in the existing network, a part of the traffic of the existing network is transmitted using the additional network.   2. A part of the traffic of the existing network is transmitted using the additional network when a failure occurs in at least one of a node device and a transmission path in the existing network. 2. The autonomous network according to 2.   The node device in the existing network is divided into a plurality of groups, the node device in the additional network is assigned to each group, the node device in each group in the existing network, the node device in the additional network, The autonomous network according to any one of claims 1 to 3, wherein the autonomous network is connected.   5. The autonomous network according to claim 4, wherein an interface card is added to the node device in the existing network, and the node device in the existing network is connected to the node device in the additional network.   6. The autonomous network according to claim 1, wherein the node device in the existing network includes a switching control unit that controls switching to the additional network. The switching control unit
7. The autonomous network according to claim 6, wherein, when a failure occurs in the existing network, switching to the additional network and controlling to transmit a part of the traffic using the additional network. The switching control unit
7. The autonomous network according to claim 6, wherein when the path in the existing network changes, the network is switched to the additional network, and a part of the traffic is controlled to be transmitted using the additional network. The switching control unit
The autonomous network according to claim 6, wherein, when a failure in the existing network is recovered, control is performed so as to switch to the additional network and transmit a part of the traffic using the additional network. A node device that constitutes an autonomous network that uses the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
The node device in the existing network is:
Switching to the additional network, and transmitting a part of the traffic of the existing network using the additional network. The node device is
When a failure occurs in at least one of the node device itself and a transmission path to the node device, the node device is switched to the additional network, and a part of the traffic on the transmission path to the node device is transferred to the additional network. The node device according to claim 10, wherein the node device is used for transmission. A first interface card for connecting to a node device of the existing network;
The node device according to claim 10, further comprising: a second interface card for connecting to the node device of the additional network.   The node device according to any one of claims 10 to 12, further comprising a switching control unit that controls switching to the additional network. A network redundancy method performed in an autonomous network using the same routing protocol inside the network,
Adding an additional network, which is an autonomous system dedicated to a backup route, to an existing network, which is an existing autonomous system, to make it redundant, and transmitting a part of the traffic of the existing network using the additional network. A characteristic network redundancy method.   The network redundancy method according to claim 14, wherein, when a failure occurs in the existing network, a part of the traffic of the existing network is transmitted using the additional network. A network redundancy method performed in an autonomous network using the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
The node device in the existing network is:
A network redundancy method comprising the steps of switching to the additional network and transmitting a part of the traffic of the existing network using the additional network. The node device is
When a failure occurs in at least one of the node device itself and a transmission path to the node device, the node device is switched to the additional network, and a part of the traffic on the transmission path to the node device is transferred to the additional network. 17. The network redundancy method according to claim 16, wherein the network redundancy method is used for transmission. A network redundancy program to be executed in an autonomous network that uses the same routing protocol inside the network,
The autonomous network is
An existing network, which is an existing autonomous system, is made redundant by adding an additional network, which is an autonomous system dedicated to the backup route,
A network redundancy program for causing a node device in the existing network to execute a process of switching to the additional network and transmitting a part of the traffic of the existing network using the additional network.   When a failure occurs in at least one of the node device itself and a transmission path to the node device, the node device is switched to the additional network, and a part of the traffic on the transmission path to the node device is transferred to the additional network. 19. The network redundancy program according to claim 18, wherein the node device is caused to execute processing to be used and transmitted.

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