JP4335945B2 - Ad hoc network system and its node equipment - Google Patents

Description

  The present invention relates to an ad hoc network system and a node device constituting the ad hoc network system.

  With the recent progress of wireless communication technology and the miniaturization and advancement of electronic devices, communication between communication devices is possible without using existing network infrastructure, compared to the conventional infrastructure type communication form. Interest in ad hoc network systems is growing. This ad hoc network system has the following characteristics, unlike a conventional fixed infrastructure type network (for example, a network system configured to communicate via an access point). is doing.

(1) Communication between objects and devices.
(2) It is possible to construct an autonomous network with a huge number of objects and devices.
(3) A network independent of existing communication infrastructure can be constructed.
(4) A simple and temporary network can be constructed.
(5) Autonomy is required to cope with topology changes.

  Currently, various routing protocols (ad hoc routing protocols) to be applied to an ad hoc network system have been proposed in order to satisfy the above characteristics (see, for example, Non-Patent Documents 1 to 3).

  Here, Non-Patent Document 1 (DSR) and Non-Patent Document 2 (AODV) are documents showing an on-demand type routing protocol. According to these protocols, when a communication request occurs, a route from the transmission source to the transmission destination is set, and an environment for performing predetermined communication is provided.

  Non-Patent Document 3 (OLSR) is a document showing a proactive routing protocol. According to this protocol, by constantly exchanging route information, an environment is provided that allows communication to be started based on the route information held when a communication request occurs.

  These DSR, AODV, and OLSR routing protocols are classified as flat routing protocols because the network is formed by a single ad hoc routing protocol. -Unlike routing protocols, it is called a hierarchical routing protocol that performs route search and control hierarchically by grouping each node device in a cluster (or zone) with the aim of supporting large-scale networks. Various routing protocols have also been proposed (see, for example, Non-Patent Documents 4 to 7).

DSR (Dynamic Source Routing) -draft-ietf-manet-dsr-10. txt) AODV (Ad Hoc On-demand-distance Vector Routing): RFC3561 OLSR (Optimized Link State Routing): RFC3626 CGSR (Clusterhead-Gateway Switch Routing): “Routing and Multicast in Multihop, Mobile Wireless Networks,” Proc. IEEE ICUPC '97, October, 1997 HSR (Hierarchical State Routing): “A Wireless Hierarchical Routing Protocol with Group Mobility,” Proc. IEEE WCNC '99, September, 1999 ZRP (Zone Routing Protocol), “The Performance of Query Control Schemes for the Zone Routing Protocol,” ACM / IEEE Transactions on Networking, August 1 LANMAR (Landmark Ad Hoc Routing Protocol): “Landmark Routing for Large Scale Wireless Wireless Hoc Networks with Mobility Mobility,” Proc. ACM / IEEE MOBHOC 2000, August, 2000

  However, in the conventional pro-active type routing protocol represented by the OLSR and the like, the topology information of each node device increases depending on the number of node devices in the network. In the multi-hop network composed of the node devices, the table size managed by each node device increases, and there is a problem that enormous memory resources are required.

  On the other hand, in the conventional on-demand type routing protocol represented by the above AODV, DSR, etc., the path is established only when communication is performed, so the memory resources required in each node device are communication performed simultaneously. Will depend on the number of Therefore, the influence on the memory resource of each node device is small compared to the pro-active type routing protocol.

  However, in future ad hoc network systems, when a notification from a certain sensor node device to a specific node device is assumed, the concentration of communication to the node devices in the vicinity of the specific node device and various sensor nodes It is necessary to consider the occurrence of communication via node devices, which have a large restriction on memory resources due to the presence of communication between devices. Each node device, even if it is an on-demand type routing protocol The existence of problems such as route search that exceeds the memory resources secured in the network is becoming obvious.

  Also, in a conventional hierarchical routing protocol in which a plurality of node devices are clustered and route search / control is performed hierarchically, when maintaining a cluster that is an aggregate of a plurality of node devices, Since the exchange of messages is frequently performed, the overhead associated with the exchange of messages increases, and there is a problem that the processing is concentrated on the node device (cluster head) serving as the representative node device of the cluster.

  The present invention has been made in view of the above, and in an ad hoc network system in which a plurality of node devices autonomously constitutes a network, each relay node device constituting the ad hoc network system is in the same direction. It is an object of the present invention to provide an ad hoc network system and its node device that effectively reduce the route information of a relay node device located in the corresponding route when holding a plurality of routes toward the destination.

  Also, in an ad hoc network system in which a plurality of node devices autonomously form a network, each relay node device itself constituting the ad hoc network holds in its own node device according to its own memory resources An object of the present invention is to provide an ad hoc network system and its node device that effectively reduce route information.

  In order to solve the above-described problems and achieve the object, the present invention provides an ad hoc network system in which a plurality of node devices autonomously form a network based on an on-demand routing protocol. When there is a route search request from a plurality of node devices to the communication destination node device, and the route for which the search request has been made is used continuously, the message to the predetermined communication destination node device is relayed The relay node device that does not need a response operation to a route search request for the predetermined communication destination node device in the relay node device located between itself and the predetermined communication destination node device. Is set between itself and the predetermined communication destination node device.

  According to the present invention, when there is a route search request from a plurality of node devices to the same communication destination node device, and the route for which the route search request has been used is continuously used, the same communication destination Since the virtual tunnel is autonomously formed between the relay node device that relays the message to the node device and the same communication destination node device, the relay processing of other node devices located in the virtual tunnel becomes unnecessary, In these other node devices, it becomes possible to reduce the route information and the processing for maintaining and managing the route, so that an effect of constructing an efficient system can be obtained.

1 is a diagram showing a configuration of an ad hoc network system according to a first exemplary embodiment of the present invention in which a plurality of nodes autonomously configure a network. It is a figure for demonstrating the route search procedure at the time of performing communication between the nodes in an ad hoc network system. It is a chart which shows an example of the routing table in node 101-X in an ad hoc network system. It is a figure which shows an example of the transfer sequence in the state in which the virtual tunnel was established. It is a graph which shows an example of the path | route table in node 101-X after a virtual tunnel is established between node 101-X and node 101-Y. It is a chart which shows an example of the routing table in the relay node between node 101-X and node 101-Y after a virtual tunnel is established between node 101-X and node 101-Y. It is a graph which shows an example of the path | route table in node 101-Y after a virtual tunnel is established between node 101-X and node 101-Y. It is a figure which shows the transfer sequence in the maintenance / management of the route table after virtual tunnel establishment. It is a figure which shows the transfer sequence when a new node is added after virtual tunnel establishment. It is a figure for demonstrating the characteristic of the ad hoc network system concerning Embodiment 2 of this invention, and is the figure which extracted arbitrary 3 nodes on the network which comprises the ad hoc network system shown in FIG. is there. It is a figure which shows the transfer sequence at the time of establishing a virtual tunnel between adjacent nodes, and the establishment request of a virtual tunnel with respect to an adjacent node between each node which has a positional relationship as shown in FIG.

  Hereinafter, various embodiments for explaining an ad hoc network system and a node device thereof according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
First, the ad hoc network system according to the first exemplary embodiment of the present invention will be described.

(System configuration)
FIG. 1 is a diagram showing a configuration of an ad hoc network system according to a first exemplary embodiment of the present invention in which a plurality of node devices (hereinafter simply referred to as “nodes”) autonomously configure a network. In the ad hoc network system 100 shown in the figure, nodes 101 constituting the system or a node group 110 constituted by a plurality of nodes 101 and the nodes 101 are connected by one or more wireless links 102.

  In addition, the function is exhibited by performing predetermined communication based on the above-described ad hoc routing protocol such as on-demand DSR or AODV between the wireless links 102. The node group 110 includes a plurality of intermediate nodes (relay nodes). For example, the communication between the node 101-B and the node 101-X is performed by a plurality of nodes (relays) constituting the node group 110. Node).

(Route search procedure)
Next, a route search procedure in the ad hoc network system according to the first embodiment will be described. FIG. 2 is a diagram for explaining a route search procedure when communication between nodes in the ad hoc network system is performed. The portion indicated by the broken line in FIG. 6 indicates the presence of a plurality of relay nodes similar to the node group 110 shown in FIG. 1. For example, the nodes 101 -F, 101 -Y, and 101 -X and the node 101-Y are connected via a plurality of relay nodes.

  In FIG. 2, when the node 101-A in the ad hoc network system communicates with the node 101-Y, first, a route search request message (Route Request) directed to the node 101-Y is sent to the ad hoc network. The route search procedure to the node 101-Y as the transmission destination is started (floating) (sequence SQ101).

  On the other hand, the node that receives the Route Request determines that the destination node included in the Route Request is not its own node, and the determination is based on the combination of the sequence number included in the Route Request and other information (this determination process is referred to as “Reception Route Request”). If it is determined that the corresponding Route Request is unprocessed as a result of “check for duplication”, the received Route Request is flooded again in the network (sequence SQ102). At this time, route information (Reverse Path: hereinafter referred to as “reverse route information”) that returns to the transmission source of the corresponding Route Request is registered in its own route table (sequence SQ103).

  On the other hand, the node specified as the transmission destination node included in the route search request message (Route Request), when the route to the transmission destination of the received Route Request is optimal with respect to the reception of the Route Request, A route search response message (Route Reply) is notified to the node 101-A that is the source of the request (sequence SQ104).

  Here, the Route Reply notified from the transmission destination node is transferred along the route information (Reverse Path) that returns from the transmission destination node registered in each node to the transmission source node by flooding of the Route Request. In other words, the node that receives the Route Reply registers the route information (Forwarding Path: hereinafter referred to as “forwarding route information”) for the source node of the Route Reply in its own route table and the reverse route that has been registered in the route table. The received Route Reply is transferred according to the information (sequence SQ105).

  Similarly, when the node 101-B, the node 101-C, and the like communicate with the node 101-Y, a route search procedure toward the transmission destination node 101-Y is performed, and the node 101-B and the node 101 A path between each node with -C and the node 101-Y is determined.

  With this sequence, at each node on the path between the node 101-B and the node 101-Y, the transfer path information for the node 101-B is registered in its own path table, and the node 101 Reverse route information tracing in the reverse direction with -Y as the transmission source is registered in its own route table. Similarly, in each node on the route between the node 101-C and the node 101-Y, the transfer route information toward the node 101-C and the reverse route information returning to the node 101-C are stored in its own route table. Registered in

(Route table)
FIG. 3 is a chart showing an example of a route table in the node 101-X in the ad hoc network system. In this route table, the source node identifier 21, the destination node identifier 22, the next hop (forwarding destination) node identifier 23, the status flag 24, the lifetime 25, and other elements 26 are held, and the same transmission is performed. N (N is a predetermined natural number) route information destined for the destination node and M (M is a predetermined natural number) reverse route information traced in the reverse direction with the same destination node as the source node are registered. .

  For example, as shown in FIG. 3, in the node 101-X located on the path of the node 101-E and the node 101-Y, N pieces of transfer path information toward the node 101-Y and the node 101-Y are M pieces of reverse route information as transmission sources are registered in its own route table.

(Virtual tunnel concept)
Next, the concept of a virtual tunnel common to the embodiments of the present invention will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a transfer sequence in a state where a virtual tunnel is established. Note that the example shown in FIG. 6 illustrates a case where the node 101-E starts communication with the node 101-Y when the nodes 101-A, B, and C are communicating with the node 101-Y. It is assumed.

  In FIG. 4, prior to communication with the node 101-Y, the node 101-E floods a route search request message (Route Request) (sequence SQ201). The Route Request flooded by the node 101-E is received by the node 101-X via a plurality of relay nodes in the ad hoc network. The node 101-X performs a route search toward the node 101-Y in order to transmit a tunnel establishment request message (Tunnel Request) described later to the node 101-Y (sequence SQ202).

  At this time, in the relay node between the node 101-X and the node 101-X, processing such as flooding of the route request based on the above-described route search procedure and reception / reply of the route reply is performed, and the node 101-X And the node 101-Y is established. This route search can be omitted when the route to the node 101-Y is known.

  After the path between the node 101-X and the node 101-Y is established, the node 101-X notifies the node 101-Y of a tunnel establishment request message (Tunnel Request) by unicast (sequence). SQ203). Here, the virtual tunnel Tunnel Request includes reverse path information (nodes 101-A, 101-B, and 101-C) for the request destination of the virtual tunnel. Each node on the path between the node 101-X and the node 101-Y that receives the virtual tunnel Tunnel Request transfers the virtual tunnel Tunnel Request according to the path information held in the path table of each node (sequence SQ204).

  Node 101-Y notifies tunnel establishment response message (Tunnel Reply) to node 101-X in accordance with the information included in the received virtual tunnel Tunnel Request (sequence SQ205). The Tunnel Request includes nodes 101-A, 101-B, and 101-C as nodes accommodated in the virtual tunnel, and the route information of the nodes 101-A, 101-B, and 101-C is directed to the virtual tunnel. Update to

  After such processing is performed, the node 101-X receives the virtual tunnel Tunnel Reply, thereby establishing a virtual tunnel between the node 101-X and the node 101-Y. Then, a Route Reply that is a response to the Route Request from the node 101-E is transferred (sequence SQ206).

  Here, in the nodes on the route of the node 101-X and the node 101-Y, the route information for the nodes 101-A, 101-B, and 101-C included in the tunnel establishment request message (Tunnel Request) is the node 101 Since the message is transferred on the virtual tunnel between −X and the node 101-Y, the message is not transferred based on the corresponding route information. Therefore, the corresponding route information in the relay nodes such as the nodes 101-A, 101-B, and 101-C is deleted from the route table after a predetermined time has elapsed. Such a situation is shown in the charts of FIGS.

(Route table after establishing a virtual tunnel)
For example, FIG. 5 is a chart showing an example of a route table in the node 101-X after the virtual tunnel is established between the node 101-X and the node 101-Y, and FIG. FIG. 7 is a diagram illustrating an example of a route table in a relay node between the node 101-X and the node 101-Y after the virtual tunnel is established between the node 101-Y and FIG. It is a graph which shows an example of the path | route table in node 101-Y after a virtual tunnel is established between X and node 101-Y.

  As apparent from comparison between the charts shown in FIGS. 5 and 7 and the chart shown in FIG. 6, the size of the routing table in the relay node between the node 101-X and the node 101-Y is significantly reduced. be able to. Therefore, it is possible to greatly reduce the memory resource requirement at the relay node.

  Note that a node located on the path between the node 101-X and the node 101-Y steals a tunnel establishment request message (Tunnel Request) or a tunnel establishment response message (Tunnel Reply), so that a tunnel establishment request message (Tunnel). It is also possible to delete the transfer route information and the reverse route information for the nodes 101-A, 101-B, and 101-C included in (Request) from the route table of the own node.

(Transfer sequence after virtual tunnel establishment)
FIG. 8 is a diagram showing a transfer sequence in maintenance / management of the route table after the virtual tunnel is established. In general, a route search procedure is performed at regular intervals between nodes where a route is established in order to maintain and manage (transfer route information / reverse route information) in the established route. For example, as illustrated in FIG. 8, the node 101-A floods a route search request message (Route Request) in order to maintain and manage the route table held by itself (sequence SQ301).

  On the other hand, the node 101-X that has established the virtual tunnel in its own route table sends a route search response message (Route) instead of the node 101-Y to the Route Request addressed to the node 101-Y that is the end of the virtual tunnel. “Reply” is returned as a proxy (sequence SQ302). This proxy response process is also performed for the nodes 101-B, 101-C, and 101-E as shown in FIG.

  Further, the node 101-X receives a periodic route search request message (Route Request) for maintaining / managing routes from the nodes 101-A, 101-B, 101-C, and 101-E. Independently, the node 101-Y that is the end of the virtual tunnel is periodically flooded with a Route Request for route maintenance / management (sequence SQ303), and the node 101-Y that is the request destination of the virtual tunnel is also sent to the node 101-Y. On the other hand, a tunnel establishment request message (Tunnel Request) for maintaining / managing the route (reverse route information) is periodically notified (sequence SQ304).

  By these processes, a virtual tunnel between the node 101-X and the node 101-Y is maintained, and as shown in the example of the route table in FIG. 6, the node 101-X and the node 101-Y It is possible to reduce the size of the routing table in the intermediate node.

(Transfer sequence when adding a new node)
FIG. 9 is a diagram showing a transfer sequence when a new node is added after the virtual tunnel is established. In this case, first, the node 101-F floods a route search request message (Route Request) for the node 101-Y in order to newly communicate with the node 101-Y (sequence SQ401).

  At this time, when the node 101-X that has already established a virtual tunnel with the node 101-Y receives this Route Request, the node 101-Y responds with a route search response message (Route Reply) instead of the node 101-Y. At the same time (sequence SQ402), the node 101-Y is notified of a tunnel establishment request message (Tunnel Request) in which the node 101-F is newly added as reverse path information for the virtual tunnel request destination (sequence SQ403).

  Thereafter, when the node 101-X receives the tunnel establishment response message (Tunnel Reply) from the node 101-Y (sequence SQ404), even when a new node 101-F is added, the node 101-X A virtual tunnel with the node 101-Y is maintained.

  Note that, once the virtual tunnel is formed, each of the node devices located at both ends of the virtual tunnel can make a proxy response to a route search request message (Route Request) directed to the virtual tunnel. For example, in the above example, the case where the node 101-X that has received the route search request message (Route Request) for the node 101-Y sends a proxy response to the transmission source node instead of the node 101-Y. In contrast to this, the node 101-Y that has received the route search request message (Route Request) for the node 101-X sends a proxy response to the transmission source node instead of the node 101-X. To come.

  In the above example, the virtual tunnel formed between the node 101-X and the node 101-Y is shown. However, the number of virtual tunnels having the node 101-X as one end is not limited to one. A virtual tunnel can be formed with any other node device.

  As described above, in this embodiment, the relay nodes constituting the ad hoc network system have a route search request from a plurality of nodes to the same transmission destination, and are continuously using the route. In this case, a virtual tunnel is autonomously formed between the relevant relay node and the relevant destination node, so that a plurality of routes are aggregated into the virtual tunnel, so that it is located between the relevant relay node and the relevant destination node. It is possible to reduce the route information held in the relay node.

  In this embodiment, the node that is the end point of the autonomously formed virtual tunnel responds with a route search response message on behalf of the route search request message for route maintenance and management, and Independent of the maintenance and management of the route by the node that communicates via the virtual tunnel, the route is maintained and managed between the end nodes of the virtual tunnel, and the node information that communicates through the virtual tunnel is maintained and managed. At the same time, a route search response message is sent as a proxy at one end node of the virtual tunnel to a node that newly communicates via the virtual tunnel. Reduce the amount of route search request messages and route search response messages for maintaining and managing routes An ability, it is possible to reduce the overhead needed to maintain and manage routing information.

  In addition, by using the route information reduction method according to this embodiment, it is possible to more efficiently design and construct an ad hoc network system.

Embodiment 2. FIG.
Next, an ad hoc network system according to the second exemplary embodiment of the present invention will be described. In the first embodiment, the method of aggregating the route to the transmission destination in the relay node that processes the route search request message has been described. However, in this embodiment, each node constituting the ad hoc network system automatically This is a technique for requesting establishment of a virtual tunnel between adjacent nodes and increasing the path information in the node as the path information in the node increases.

  FIG. 10 is a diagram for explaining the features of the ad hoc network system according to the second exemplary embodiment of the present invention, and arbitrary three nodes on the network constituting the ad hoc network system 100 shown in FIG. It is the figure which extracted 101-L, 101-M, and 101-N. In FIG. 10, a node 101-M and a node 101-N are positioned as adjacent nodes of the node 101-L, and the node 101-M, the node 101-L, and the node 101-N are connected via the wireless link 102. Connected. Reference numeral 103 denotes a route through the 101-M and the nodes 101-L and 101-N.

(Transfer sequence based on virtual tunnel establishment request)
Next, a transfer sequence in the ad hoc network system according to the second embodiment will be described with reference to FIG. FIG. 11 is a diagram showing a virtual tunnel establishment request to an adjacent node and a transfer sequence when establishing a virtual tunnel between adjacent nodes between the nodes having the positional relationship as shown in FIG.

  First, as shown in FIG. 11, it is assumed that a path is established between the node 101-M and the node 101-N adjacent to the node 101-L. From this state, for example, when the node 101-L detects the possibility of overflow in its own route table due to an increase in transfer route information or reverse route information, it requests a virtual tunnel establishment request. It determines (sequence SQ501), and transmits a tunnel establishment request message (tunnel solicitation) to adjacent nodes 101-M and 101-N (sequence SQ502).

  On the other hand, the nodes 101-M and 101-N that have received the tunnel establishment request message (Tunnel Solicitation) transmit a tunnel establishment request message to the nodes 101-N and 101-M, respectively, after an arbitrary random time has elapsed. To do. Note that when the tunnel establishment request message has already been received, the transmission of the tunnel establishment request message (Tunnel Request) is cancelled.

  In the example shown in FIG. 11, since the tunnel establishment request message (Tunnel Request) from the node 101-M has been transmitted first (sequence SQ503), the node 101-N that has received this tunnel establishment request message (Tunnel Request). Responds with a tunnel establishment response message (Tunnel Reply) addressed to the node 101-N that is the transmission source of the tunnel establishment request message (Tunnel Request) (that is, between both node devices) (sequence SQ504). In this way, a virtual tunnel is established between the node 101-M and the node 101-N (sequence SQ505).

  As described above, in this embodiment, each node constituting the ad hoc network system autonomously requests a transfer using a virtual tunnel to an adjacent node according to the increasing route information. By doing so, it is possible to reduce the route information held in the own node.

  In addition, by using the route information reduction method according to this embodiment, it is possible to more efficiently design and construct an ad hoc network system.

  As described above, the present invention is useful for an ad hoc network system in which a plurality of node devices autonomously form a network.

Claims (12)

In an ad hoc network system in which multiple node devices autonomously form a network based on an on-demand routing protocol,
When there is a route search request from a plurality of node devices for a predetermined communication destination node device, and the route for which the route search request has been used is continuously used,
The relay node device that relays a message to the predetermined communication destination node device is a route search request for the predetermined communication destination node device in the relay node device located between itself and the predetermined communication destination node device. An ad hoc network system, characterized in that a virtual tunnel for making a response operation to a node unnecessary is set between itself and the predetermined communication destination node device.   A node device at one end of the node devices located at both ends of the virtual tunnel is replaced with a relay node device located between itself and the node device at the other end that is the predetermined communication destination node device. 2. The ad hoc network system according to claim 1, wherein a proxy response is made to a route search request directed to an end node device. The node device includes a route table that holds route information including a plurality of next transfer destination node information for relaying and transmitting a message directed to the predetermined communication destination node device,
The relay node device in the virtual tunnel deletes entries other than the node devices located at both ends of the virtual tunnel from the route information including the predetermined communication destination node device held in the route table of the virtual tunnel. The ad hoc network system according to claim 2.   The ad hoc network system according to claim 3, wherein the relay node device in the virtual tunnel deletes entries other than the node devices located at both ends of the virtual tunnel after a predetermined time elapses. When forming the virtual tunnel, a tunnel establishment request message is transmitted from the relay node device that relays a message to the predetermined communication destination node device to the predetermined communication destination node device, and the predetermined communication is performed. A tunnel establishment response message is transmitted to the relay node device that relays the message from the destination node device to the predetermined communication destination node device,
The relay node device in the virtual tunnel deletes entries other than the node devices located at both ends of the virtual tunnel with reference to information included in the tunnel establishment request message or the tunnel establishment response message. The ad hoc network system according to claim 3.   6. The ad hoc network according to claim 3, wherein the node device transmits a tunnel establishment request message for requesting formation of a virtual tunnel to a node device adjacent to the node device. system.   The tunnel establishment request message is transmitted from one node device determined by the system to the other node device among the one and other node devices that have received the request for the virtual tunnel, and the other node device The ad hoc network system according to claim 6, wherein the tunnel establishment response message is transmitted toward the one node device. In an ad hoc network system node device that forms an autonomous network based on an on-demand routing protocol,
When there is a route search request from a plurality of node devices for a predetermined communication destination node device different from itself, and the route for which the search request has been used is continuously used,
When relaying a message to the predetermined communication destination node device, a response to a route search request for the predetermined communication destination node device in the relay node device located between itself and the predetermined communication destination node device A node device characterized in that a virtual tunnel for making a response operation unnecessary is set between itself and the predetermined communication destination node device.   A node device at one end of the node devices located at both ends of the virtual tunnel is replaced with a relay node device located between itself and the node device at the other end that is the predetermined communication destination node device. The node device according to claim 8, wherein a proxy response is made to a route search request directed to an end node device. A path table that holds path information including a plurality of next transfer destination node information for relaying and transmitting a message directed to the predetermined communication destination node apparatus;
After the formation of the virtual tunnel, entries other than the node devices located at both ends of the virtual tunnel in the route information including the predetermined communication destination node device held in the route table of the relay node device in the virtual tunnel The node device according to claim 9, wherein is deleted.   The node device according to claim 8, wherein the node device transmits a tunnel establishment request message for requesting formation of a virtual tunnel to a node device adjacent to the node device.   The tunnel establishment request message is transmitted from one node device determined by the system to the other node device among the one and other node devices that have received the request for the virtual tunnel, and the other node device The node device according to claim 11, wherein the tunnel establishment response message is transmitted toward the one node device.

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