JP4564442B2 - Route search device - Google Patents

Description

  The present invention relates to a route search device that searches for a route for data transfer in an ad hoc network, for example.

  An ad hoc network is a network that is autonomously generated by a plurality of nodes communicating with each other. In an ad hoc network, when a transmission source node that is a data transmission source and a destination node that is a data transmission destination do not exist in each other's communication area, a relay node positioned between the transmission source node and the transmission destination node Can be used to form a multi-hop network and transfer predetermined data from the source node to the destination node.

  However, in an ad hoc network, link disconnection frequently occurs, for example, due to movement of a relay node. Therefore, it is necessary to instantly regenerate a route, and various routing protocols have been proposed.

  Conventional ad hoc network route creation protocols can be broadly classified into a table-driven type in which a route table is created and route control is performed based on information in the route table, and an on-demand type in which a source node is started.

  First, the one that operates with the table-driven protocol tries to maintain the latest route information without any contradiction from each node on the network to all other nodes, and the route for each node to store the route information. By having one or more tables, it is possible to cope with changes in the network topology (for example, see Non-Patent Document 1).

  On the other hand, those that operate on the on-demand protocol activate route search processing in the network only when the source node that sends the data requests, and only the nodes on the route for data transfer display the route table. A node that is created and not on the route is configured not to create a route table, and a node on the route can transfer data from the source node to the destination node based on the information in the route table. (See, for example, Non-Patent Document 2).

P. Jacquet, P.M. Muhlethaler, A.M. Qayum, A .; Lanouiti, L.M. Viennot and T.W. Clausen, IETF MANET Internet Draft “draft-ietf-MANET-olsr-02.txt”, July 2000. C. E. Perkins and E.M. M.M. Royer, "Ad-hoc On Demand Distance Vector Routing", Second IEEE Works on Mobile Computing Systems and Applications, pp. 90-100, February 1999.

  However, those that operate using the table-driven protocol need to transmit route update information to the entire network in response to changes in the network topology. There was a problem that the amount of traffic increased.

  In addition, those that operate on the on-demand driven protocol start route creation after a request from the transmission source node, so that a predetermined time is required until the route is established. When the link is broken, the route is temporarily interrupted, so packet arrival delay or packet loss occurs during data transfer, packet transmission is interrupted when the route is changed, and the route cannot be changed instantaneously. was there.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a route search device that can change a route instantaneously without increasing the amount of traffic.

The route search device according to the present invention includes a route search means for searching for at least one of a main route for transmitting data from a predetermined source node to a destination node and a sub route as a backup of the main route, and transmits the data. A transmission / reception means for transmitting / receiving a route control packet for performing route control, a route mode indicating that the device is on the main route, and a monitoring mode indicating that the device is on the sub route Mode setting means for setting the mode based on the route control packet, and information for transmitting the data to the destination node regardless of the mode when the main route is searched by the route search means. the routing table includes a routing table creation means for creating, based on the routing control packet, the routing control packet, the main path and the sub path A route search packet for searching for any one of them and a route reply packet corresponding to the route search packet, and the route table creating means for each address of the destination node based on the route search packet and the route reply packet The route table is created, and the route reply packet includes a route reply packet for a sub route corresponding to a route search packet for searching for the main route, and the route search means searches for the main route. The sub-route is generated based on the route search packet and the route reply packet for the sub route, and the transmission / reception means transmits the route reply packet for the sub route when the own device is set to the monitoring mode. It has a configuration to transmit periodically .

  With this configuration, the route search device of the present invention creates a route table including information for transmitting data to the destination node when the main route for transmitting data is searched. The route table can be created without increasing the traffic volume.

Also, with this configuration, the route search device of the present invention can reach the destination node if data is transmitted based on the information included in the route table, regardless of whether the device is on the main route or the sub route. Therefore, the route can be changed instantaneously without interruption of data transmission when the route is changed.
Also, with this configuration, the route search device of the present invention enables the route table creation means to create a route table for each address of the destination node based on the route search packet and the route reply packet. Regardless of the device itself, if data is transmitted based on the information contained in the route table, it reaches the destination node, and data transmission is not interrupted when the route is changed. The route can be changed instantaneously for each address.
Also, with this configuration, the route search device of the present invention generates a sub route based on the route search packet for searching the main route and the route reply packet for the sub route, so that the route search unit of the present invention A spare sub route can be generated, and even if a node moves on the main route, the data transmission route can be instantly changed from the main route to the sub route without interrupting the data. It can be transmitted to the destination node.
Also, with this configuration, the route search apparatus of the present invention can update the route table related to the sub route and acquire the latest sub route information even when a node moves or the like on the sub route.

The route search apparatus of the present invention includes a route search means for searching for at least one of a main route for transmitting data from a predetermined source node to a destination node and a sub route as a backup of the main route, and the data Transmitting / receiving means for transmitting / receiving a route control packet for performing route control for transmitting a route, a route mode indicating that the own device is on the main route, and a monitoring mode indicating that the own device is on the sub route. Mode setting means for setting any mode based on the route control packet; and for transmitting the data to the destination node regardless of the mode when the main route is searched by the route search means. Route table creation means for creating a route table including information based on the route control packet, and the route control packet includes the main route and the route A route search packet for searching for any one of the routes and a route reply packet corresponding to the route search packet, wherein the route table creating means includes an address of the destination node based on the route search packet and the route reply packet. The route table is created every time, and the route reply packet includes a route reply packet for a sub route corresponding to a route search packet for searching for the sub route, and the route search means searches for the sub route. The sub-route is generated based on a route search packet and a route reply packet for the sub-route, and the transmission / reception means transmits the route reply for the sub-route when the own device is set in the monitoring mode. It has the structure which transmits a packet regularly .

With this configuration, in the route search device of the present invention, the route table creation means creates a route table for each address of the destination node based on the route search packet and the route reply packet. Even if there is a local device, if data is transmitted based on the information contained in the route table, it reaches the destination node, and data transmission is not interrupted when the route is changed. In addition, the route can be changed instantaneously.
Also, with this configuration, the route search apparatus of the present invention generates a sub route based on the route search packet for searching for the sub route and the route reply packet for the sub route, so that the route search unit of the present invention A spare sub route can be generated, and even if a node moves on the main route, the data transmission route can be instantly changed from the main route to the sub route without interrupting the data. It can be transmitted to the destination node.
Also, with this configuration, the route search apparatus of the present invention can update the route table related to the sub route and acquire the latest sub route information even when a node moves or the like on the sub route.

  Further, in the route search device of the present invention, each of the route search packet and the route reply packet includes sequence number information indicating a route generation order, and the route table creation means is based on the sequence number information. The routing table is updated.

  With this configuration, the route search device of the present invention updates the route table based on the sequence number information, so that the route table creation means can acquire the latest route information from the own device to the destination node, Data can be reliably transferred to the destination node.

  The present invention can provide a route search apparatus having an effect that a route can be changed instantaneously without increasing the amount of traffic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of the route search apparatus according to the present embodiment will be described with reference to FIGS. FIG. 1 is a block diagram of a route search apparatus according to the present embodiment. FIG. 2 is an explanatory diagram of a route generated by the route search device according to the present embodiment. An example in which the route search device according to the present embodiment searches for a route in an ad hoc network will be described.

  As shown in FIG. 1, the route search device 10 according to the present embodiment includes a transmission / reception unit 11 connected to an ad hoc network for transmitting and receiving packets, a route search unit 12 for performing route search, a route mode and a monitoring mode. A mode changeover switch 13 for switching, a route notation unit 14 for storing data of the route table, a main route switching maintenance unit 15 for switching to the main route and maintaining the route table of the main route, and a route table of the sub route And a sub-route maintenance unit 16 that performs maintenance.

  A wireless communication system that performs multi-hop communication using an ad hoc network as shown in FIG. 2 can be constructed by a plurality of nodes each including the route search device 10 according to the present embodiment.

  In the ad hoc network shown in FIG. 2, when data transfer is attempted from a transmission source node that is a data transmission source to a destination node that is a data transmission destination, a main route for transferring data and a spare for the main route are used. A sub route is autonomously generated by a node on the network. Here, the sub route is used, for example, to compensate for packet loss occurring in the main route.

  In FIG. 2, a route indicated by a solid arrow is a main route, and a route indicated by a broken arrow is a sub route. A node on the main route is called a node on the route, and a node on the sub route is called a monitoring node. The state operating as a node on the path is referred to as a path mode, and the state operating as a monitoring node is referred to as a monitoring mode.

  In FIG. 1, the transmission / reception unit 11 includes, for example, an antenna for transmitting / receiving radio waves, a demodulation circuit, a modulation circuit, a network interface card, and the like. The transmission / reception unit 11 constitutes transmission / reception means of the present invention.

  The route search unit 12 generates a main route and a sub route by a predetermined route control packet when starting data transmission. The route search unit 12 constitutes route search means of the present invention. The route search unit 12 constitutes route table creation means for creating a route table described later.

  Specifically, the route search unit 12 performs a route search using a route control packet as shown in FIG. The route control packet includes a route search packet transmitted to search for a route and a route reply packet transmitted in response to the route search packet.

  FIG. 3A is a diagram illustrating a configuration example of a route control packet. The route control packet includes an identifier for identifying a route search packet or a route reply packet, a saddr indicating an address of a transmission source node that is a data transmission source during communication, a adddr indicating an address of a destination node, and between links Lsaddr indicating the address of the transmission source node, ldaddr indicating the address of the next hop, Mode indicating whether the packet is for the node on the route or the packet for the monitoring node, sq indicating the route sequence number, and hop indicating the number of hops from the transmission source It is composed of information including.

  Since the route control packet is configured as described above, assuming that the source node address is S and the destination node address is D, the route search packet has an identifier = search, saddr as shown in FIG. = S, daddr = D, Mode = monitoring information is included. Since this route search packet is broadcast to search for the main route, ladddr = broadcast address.

  Further, the route reply packet for the main route among the route reply packets includes identifier = reply, saddr = D, adddr = S, and Mode = route information as shown in FIG.

  On the other hand, as shown in FIG. 3 (d), the route reply packet for the sub route includes information of identifier = reply, saddr = D, daddr = S, Mode = monitor, and this route reply packet for the sub route is Since the broadcast transmission is performed to search for the sub route, ldaddr = broadcast address.

  The mode change-over switch 13 is configured to set the own apparatus to the route mode or the monitoring mode based on the Mode information included in the route reply packet for the main route or the route reply packet for the sub route. The mode switch 13 constitutes the mode setting means of the present invention.

  The route notation unit 14 stores data of the route table created by the route search unit 12 when the transmission source node starts route search. This routing table has a configuration as shown in FIG. 4 and is created for each destination.

  That is, as shown in FIG. 4, the route table includes the address of the destination node, the address of the next hop, the number of hops from the source of the route control packet to the own device, and the main route indicating the generation order of the route control packet in the main route search It includes information on the sequence number and the sub route sequence number indicating the generation order of the route control packet in the sub route search. In the following description, for example, the route table addressed to the node D includes information that the destination node address = D, the next hop address = a, the number of hops = 1, the main route sequence number = 2, and the sub route sequence number = 0. This route table is expressed as (D, a, 1, 2, 0).

  When the own device is in the monitoring mode, the main route switching maintenance unit 15 switches from the monitoring mode to the route mode when receiving a route reply packet for the main route. In addition, the main route switching maintenance unit 15 can also update the route table based on information included in the route control packet.

  When the own device is in the monitoring mode, the sub route maintenance unit 16 can update the route table when new route information is acquired due to, for example, an adjacent node moving.

  Next, the operation of the route search apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 5 shows a wireless ad hoc communication system composed of a plurality of nodes. The operation of the route search apparatus 10 will be described by explaining the operation of the wireless ad hoc communication system.

  FIG. 5 shows a source node S that transmits data, a destination node D that is a destination of data, and relay nodes a, b, and c that relay data between the source node S and the destination node D. Has been. Assume that the route search apparatus 10 according to the present embodiment shown in FIG. 1 is provided as part of the configuration of the transmission source node S, destination node D, and relay nodes a, b, and c. In FIG. 5, the addresses of the source node S, the relay nodes a, b, c, and the destination node D are represented as S, a, b, c, D, respectively.

  First, a route search is started by the transmission source node S (FIG. 5A). That is, the transmission source node S broadcasts a route search packet including information of identifier = search, saddr = S, adddr = D, lsaddr = S, ldaddr = broadcast address, Mode = monitor, sq = 0, hop = 0. To do.

  This route search packet is received by the relay nodes a and c, and the relay nodes a and c have (S, S, 1, 0) in their respective route tables based on the above-described information included in the received route search packet. , 0).

  Next, the route search packet is broadcasted by the relay nodes a, b, and c (FIG. 5B).

  First, the relay nodes a and c that have received the route search packet from the source node S change the link source address lsaddr to the own device address because the destination address saddr of the received route search packet is not the address of the own device. Then, the changed route search packet is broadcasted.

  Here, the source node S receives the route search packets from the relay nodes a and c, but discards the received route search packet because the source address saddr is the address of its own device. The relay node a also receives the route search packet from the relay node c, but has already received the route search packet with the same destination and the same route sequence number sq from the transmission source node S. The route search packet is discarded. Similarly, the relay node c also discards the route search packet received from the relay node a.

  Next, the relay node b receives the route search packet from the relay node c, and in the route table (S, c, 2, 0, 0), that is, c, the next hop as the route to the source node S, hop Register the number as 2. The relay node b also receives the route search packet from the relay node a, but discards the route search packet received from the relay node a because the same packet is received from the relay node c.

  Subsequently, the destination node D receives the route search packet from the relay node a and registers (S, a, 2, 0, 0) in the route table. The destination node D also receives the route search packet from the relay node b, but has already received the route search packet with the same destination and the same route sequence number sq from the relay node a. Discard the route search packet.

  Next, the destination node D that has received the route search packet transmits a route reply packet corresponding to the route search packet toward the transmission source node S (FIG. 5C).

  First, since the destination address saddr of the route search packet received by the destination node D is the address of its own device, the route reply packet for the sub route including Mode = monitoring information is sent to the source node S by the destination node D. Broadcast.

  Next, the relay nodes a, b and c sequentially receive the route reply packets for the sub route broadcast and transmit the route route to the destination node D in the same manner as when the route search packet from the source node S is received. A table is created at each relay node. However, unlike when a route search packet is received, each relay node is set as a monitoring mode by the mode switch 13 of each relay node.

  Further, the route reply packet for the main route including Mode = route information is unicasted toward the transmission source node S by the destination node D. That is, since the route table of the destination node D is (S, a, 2, 0, 0), the route reply packet for the main route is transmitted to the relay node a as the link destination address ldaddr = a.

  Next, a route reply packet for the main route is received by the relay node a. Here, since the relay node a has already received the route reply packet for the sub route including Mode = monitoring information, the relay node a is in the monitoring mode. However, Mode = route reply for the main route including the route information. When the packet is received, the route table is overwritten and updated by the main route switching maintenance unit 15 of the relay node a. Note that when the device of Mode = route receives a route reply packet for the sub route including the information of Mode = monitoring, the route table cannot be overwritten.

  When the route search unit 12 of the relay node a receives the route reply packet for the main route, the route search unit 12 re-registers the address of the destination node D as the hop number 1 as the route to the destination node D. Makes the own device's operation a node on the path. However, the relay node operating on the route node rewrites the route table only when the sequence number of the received route reply packet is large.

  Then, the source node S receives a route reply packet for the main route including Mode = route information from the relay node a. Accordingly, as illustrated in FIG. 5D, the transmission source node S can transfer, for example, a packet of video data to the destination node D via the relay node a. A solid line arrow shown in FIG. 5D indicates a main route through which data is transferred.

  In addition, the destination node D performs route management of the sub route by periodically transmitting a route reply packet for the sub route including the information of Mode = monitoring. Specifically, in the relay node operating in the monitoring mode, the transmission / reception unit 11 periodically transmits / receives a route reply packet for the sub route including Mode = monitoring information, and the sub route maintenance unit 16 Based on the information included in the reply packet, the route table from the own device to the destination node D is maintained. Note that even if the relay node operating in the route mode receives the route reply packet for the sub route including the information of Mode = monitoring, it only forwards the route table without rewriting it.

  Next, the operation of the source node S shown in FIG. 5 will be specifically described with reference to FIG. FIG. 6 is a flowchart showing an operation when the transmission source node S transmits data to the node D having no information in the routing table.

  As shown in FIG. 6, the route search packet of the transmission source node S is flooded toward the destination node D (step S11). This route search packet includes information of identifier = search, saddr = S, adddr = D, laddr = S, ldaddr = broadcast dress, sq = 0, hop = 0.

  Next, the route search unit 12 determines whether or not a route reply packet for the main route including Mode = route information is returned before a predetermined time elapses after the route search packet is broadcast. Step S12).

  If it is determined in step S12 that the route reply packet for the main route has returned within a predetermined time, the route search unit 12 creates and creates a route table based on the route reply packet for the main route. Data is transmitted to the destination node D according to the route table (step S13). The created route table data is stored by the route notation unit 14.

  On the other hand, if it is not determined in step S12 that the route reply packet for the main route has returned within the predetermined time, the process returns to step S11 and the route search packet is broadcast again. At this time, the route search unit 12 increments the route sequence number sq.

  Next, the operation when the relay nodes a, b, and c shown in FIG. 5 receive the route search packet and the route reply packet will be specifically described with reference to FIG. FIG. 7 is a flowchart of each step of the relay nodes a, b, and c.

  If a packet is received by the transmission / reception unit 11 while waiting for packet reception at a certain relay node (step S21), the route search unit 12 determines whether the received packet is a route search packet or a route reply packet ( Step S22).

  If it is determined in step S22 that the received packet is not a route search packet or a route reply packet, route selection processing, application processing, and the like are executed (step S23).

  On the other hand, if it is determined in step S22 that the received packet is a route search packet or a route reply packet, the route search unit 12 determines the route sequence number sq0 from the route table according to the saddr and Mode information of the received packet. Is acquired (step S24). If the corresponding route sequence number sq0 is not in the route table, sq0 = -1.

  Next, the route search unit 12 compares the sequence numbers sq and sq0 of the received packet (step S25). If sq0 is larger than sq, the route search unit 12 assumes that the received packet has already been received. It is judged and discarded (step S26).

  On the other hand, when sq0 is equal to or less than sq, the route search unit 12 determines that the route table is based on the received route search packet or route reply packet, destination = saddr, next hop = laddr, hop count = hop + 1, main route The sequence number is updated as sq (when Mode = route), and the sub route sequence number = sq (when Mode = monitoring) (step S27).

  Next, the route search unit 12 determines whether or not the received packet is a route search packet (step S28). If it is determined in step S28 that the received packet is a route search packet, it is determined whether or not the own node is a destination node (step S29).

  If it is determined in step S29 that the own node is the destination node, the route search unit 12 forwards the route reply packet toward saddr (step S30), and proceeds to step S21 to wait for packet reception. On the other hand, if the local node is not determined as the destination node in step S29, the route search unit 12 floods the route search packet with hop = hop + 1 toward the destination node (step S31). Advance packet reception waiting.

  If the received packet is not determined to be a route search packet in step S28, that is, if it is a route reply packet, the route search unit 12 determines whether or not the route reply packet includes Mode = monitoring information. (Step S32).

  If it is determined in step S32 that the route reply packet includes Mode = monitoring information, the mode switch 13 sets the operation mode of the own node to the monitoring mode (step S33), and the process proceeds to step S31.

  If it is determined in step S32 that the route reply packet does not include Mode = monitoring information, that is, if the route reply packet includes Mode = route information, the route search unit 12 determines whether the own node is the transmission source node. It is determined whether or not (step S34).

  In step S34, when it is determined that the own node is a transmission source node, the transmission / reception unit 11 starts data transmission (step S35).

  On the other hand, if it is determined in step S34 that the own node is not the transmission source node, the operation mode of the own node is set to the route mode by the mode switch 13 (step S36), and the route table is referred to hop = The route reply packet set to hop + 1 is unicast transmitted toward saddr (step S37), and the process proceeds to step S21 to wait for packet reception.

  When a data packet is received at a certain node I and the route to the destination node is not described in the route table, saddr = I, adddr = D, laddr = I, sq = 0, hop = hop + 1 The route search is performed by the route search packet.

  As described above, according to the route search device 10 according to the present embodiment, when a main route for transmitting data is searched, information for the route search unit 12 to transmit data to the destination node is obtained. Since the route table including the route table is created, the route table can be created without increasing the traffic volume.

  Also, according to the route search device 10 according to the present embodiment, regardless of whether the device is on the main route or the sub route, if the data is transmitted based on the information included in the route table, Since it is in a reachable state, it is possible to change the route instantaneously without interruption of data transmission when changing the route.

  Further, according to the route search device 10 according to the present embodiment, the route search unit 12 creates a route table for each address of the destination node based on the route search packet and the route reply packet. Regardless of whether the device is on the upper route or the sub route, if data is transmitted based on the information contained in the route table, it reaches the destination node, and data transmission is interrupted when the route is changed. Instead, the route can be changed instantaneously for each address of the destination node.

  Moreover, according to the route search device 10 according to the present embodiment, the route search unit 12 is configured to update the route table based on the sequence number information, so the latest route information can be acquired, Data can be reliably transferred from its own device to the destination node.

  Further, according to the route search device 10 of the present embodiment, the route search unit 12 generates the main route based on the route search packet for searching the main route and the route reply packet for the main route. Therefore, it is possible to generate a main route for transmitting data from the transmission source node to the destination node.

  Further, according to the route search device 10 according to the present embodiment, the route search unit 12 generates a sub route based on the route search packet for searching for the main route and the route reply packet for the sub route. Therefore, it is possible to generate a secondary route as a spare for the main route, and even when a node moves on the main route, the route for transmitting data is instantly changed from the main route to the sub route. Data can be transferred to the destination node without interruption.

  Moreover, according to the route search device 10 according to the present embodiment, the route search unit 12 generates a sub route based on a route search packet for searching for a sub route and a route reply packet for the sub route. Therefore, it is possible to generate a secondary route as a spare for the main route, and even when a node moves on the main route, the route for transmitting data is instantly changed from the main route to the sub route. Data can be transferred to the destination node without interruption.

  Further, according to the route search device 10 according to the present embodiment, the transmission / reception unit 11 is configured to periodically transmit the route reply packet for the sub route when the own device is set to the monitoring mode. Even when a node moves on the sub route, the latest sub route information can be acquired by updating the route table related to the sub route.

  As described above, the route search device according to the present invention has an effect that the route can be instantaneously changed without increasing the traffic amount, and searches for a route for data transfer in an ad hoc network. Useful as such.

Block diagram of route search apparatus according to the present embodiment Explanatory drawing of the path | route produced | generated by the some node each provided with the route search apparatus which concerns on this Embodiment The figure which shows the structural example of the route control packet which the route search part of the route search apparatus which concerns on this Embodiment uses at the time of a route search (a) The figure which shows the structural example of a route control packet (b) The structural example of a route search packet is shown (C) A diagram showing a configuration example of a route reply packet for a main route (d) A diagram showing a configuration example of a route reply packet for a sub route The figure which shows the structural example of the route table produced by the route search part of the route search apparatus which concerns on this Embodiment. The figure which shows the operation | movement of the radio | wireless ad hoc communication system comprised by the some node each provided with the route search apparatus which concerns on this Embodiment (a) The figure which shows the state where the route search was started (b) The route search packet is broadcast (C) A diagram showing a state where a route reply packet corresponding to a route search packet is transmitted to the transmission source node S. (d) A packet such as video data is sent to the destination node D via the relay node a. Diagram showing the state to be transferred The flowchart which shows the operation example of the transmission origin node S provided with the route search apparatus which concerns on this Embodiment. The flowchart which shows the operation example of relay node a, b, and c provided with the route search apparatus which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Path | route search apparatus 11 Transmission / reception part 12 Path | route search part 13 Mode switch 14 Path notation billion part 15 Main path switching maintenance part 16 Sub route maintenance part

Claims (3)

Route search means for searching for at least one of a main route for transmitting data from a predetermined source node to a destination node and a sub route as a backup of the main route, and a route for performing route control for transmitting the data The route control packet includes one of a transmission / reception means for transmitting / receiving a control packet, a route mode indicating that the own device is on the main route, and a monitoring mode indicating that the own device is on the sub route. A mode setting unit configured to set a route table including information for transmitting the data to the destination node regardless of the mode when the main route is searched by the route search unit. and a routing table creation means for creating, based on,
The route control packet includes a route search packet for searching for either the main route or the sub route and a route reply packet corresponding to the route search packet,
The route table creation means creates the route table for each address of the destination node based on the route search packet and the route reply packet,
The route reply packet includes a route reply packet for a sub route corresponding to a route search packet for searching for the main route,
The route search means generates the sub route based on a route search packet for searching the main route and a route reply packet for the sub route,
The route search device , wherein the transmission / reception means periodically transmits a route reply packet for the sub route when the own device is set in the monitoring mode . Route search means for searching for at least one of a main route for transmitting data from a predetermined source node to a destination node and a sub route as a backup of the main route, and a route for performing route control for transmitting the data The route control packet includes one of a transmission / reception means for transmitting / receiving a control packet, a route mode indicating that the own device is on the main route, and a monitoring mode indicating that the own device is on the sub route. Mode setting means for setting based on the route control packet, and a route table including information for transmitting the data to the destination node regardless of the mode when the route search means searches for the main route. And a routing table creation means to create based on
The route control packet includes a route search packet for searching for either the main route or the sub route and a route reply packet corresponding to the route search packet,
The route table creation means creates the route table for each address of the destination node based on the route search packet and the route reply packet,
The route reply packet includes a route reply packet for a sub route corresponding to a route search packet for searching for the sub route,
The route search means generates the sub route based on a route search packet for searching the sub route and a route reply packet for the sub route,
The route search device , wherein the transmission / reception means periodically transmits a route reply packet for the sub route when the own device is set in the monitoring mode . Each of the route search packet and the route reply packet includes information of a sequence number indicating a route generation order,
The route search apparatus according to claim 1, wherein the route table creation unit updates the route table based on the information of the sequence number.

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