JP4605426B2 - COMMUNICATION TERMINAL DEVICE, ITS CONTROL METHOD, PROGRAM - Google Patents

Description

The present invention relates to a communication terminal apparatus, a control method therefor, and a program, and is suitable for application to an ad hoc network, for example.

  In recent years, with the spread of mobile computers such as notebook personal computers and PDAs, there is an increasing demand for a network computing environment in which these mobile computers can be connected wirelessly. One such network is an ad hoc network.

  Ad hoc networks do not have a dedicated router for relaying data, and each communication terminal (hereinafter referred to as a node) routes messages by wireless communication, thereby providing mobility, flexibility and economy. It was made to be able to construct a high network.

  In an ad hoc network in which all nodes are connected by a wireless network in this way, unlike a conventional fixed network, the topology changes very frequently, so a route control method for ensuring reliability ( Routing protocol) must be established.

  Currently proposed ad hoc network routing protocols include an on-demand method for finding a communication route to a communication destination immediately before starting communication, and a communication route for each node to each other node regardless of the presence or absence of communication. Can be roughly divided into two categories of table driving methods in which these are found in advance and held as a table. In recent years, a hybrid system integrating these has also been proposed.

  Among them, as a typical on-demand routing protocol, there is an AODV (Adhoc On-demand Distance Vector) protocol proposed by the Internet Engineering Task Force (IETF) MANET WG (Mobil Adhoc NETwork Working Group) (for example, Patent Document 1). The route discovery process in this AODV will be described below.

  FIG. 12A shows an ad hoc network system 1 constructed by a plurality of nodes A ′ to E ′ and S ′. In this figure, nodes A ′ to E ′ and S ′ that are within a mutually communicable range are connected by a line. Therefore, it is necessary to perform communication between the nodes A ′ to E ′ and S ′ that are not connected by lines via the other nodes A ′ to E ′ and S ′. In this case, the route discovery process described below is performed. Thus, the route between the nodes A ′ to E ′ and S ′ to be communicated is found.

  For example, when the node S ′ starts communication with the node D ′, and the node S ′ does not know the communication route to the node D ′, the node S ′ first sends a route request message as shown in FIG. (RREQ: Route Request) 2 is broadcast.

The route request message 2 includes “Type”, “Flag”, “Reserved”, “Hop Count”, “RREQ ID”, “Destination Address”, “Destination Sequence Number”, “Originator Address”, and “Originator Sequence Number”. field 3 ₁ is composed of a to 3 ₉ (in the case of the route request message "1") field 3 _one message of "type", for field 3 ₂ for various communication control "Flag" flag, "hop count" field 3 ₄ of the number of hops (initial value is "0"), "RREQ ID" field ₃₅ in the route request message to an applied unique ID (hereinafter, a route request message Are called IDs).

The field 3 to ₆ destination at a node D'address of the route request message "Destination Address" of the route request message 2, the node S'field 3 ₇ of the "Destination Sequence Number" is learned last node D'sequence number, field 3 ₈ the node S'address "Originator address", "Originator sequence number" field 3 ₉ the node S'sequence number of is stored, respectively.

And node A'~E' receiving this route request message 2, "Destination Address" field 3 ₆ route request message addressed to themselves based on the stored destination of the route request message 2 to of the route request message it is determined whether the 2, the field 3 broadcasts this route request message 2 ₄ stored a number of hops to in terms of increased "1" in the "hop count" when not addressed to itself.

Also the node A'~E' this time, when investigated whether node S'address which is the transmission source of the route request message 2 in its route table is present, there is no node S' Various information (entries) related to the reverse path to the path is inserted into the path table.

Here, this route table is a table to be referred to when data having the node (here, node S ′ ) as a transmission destination is received thereafter. As shown in FIG. 14, “Destination Address”, “Destination Sequence Number”, “Hop Count”, “Next Hop”, “Precursor List”, and “Life Time” fields 5 _{1 to} 5 _{6 are} configured.

The nodes A ′ to E ′, when inserting the reverse route into the route table 4, each field 5 _{1 to} 5 ₃ of “Destination Address”, “Destination Sequence Number”, or “Hop Count” of the route table 4. The data of the fields 3 ₆ , 3 ₇ , 3 ₄ of “Destination Address”, “Destination Sequence Number” and “Hop Count” in the route request message 2 are respectively copied.

The node A'~E' is the field 5 ₄ of the "Next Hop" path table 4, the neighboring node A, which has forwarded the route request message 2 to the route request message 2 is included in the header of the stored packets The addresses of '-C', E ', S' are stored. As a result, a reverse route to the node S ′ is set, and when data having the node S ′ as a transmission destination is transmitted thereafter, the corresponding “Next Hop” is based on the route table 4. the data is transferred to the node A'~E' the address described in a field 5 ₄ ".

Moreover node A'~E' stores a list of other nodes A'~E' using that route communications to field 5 ₅ in "Precursor the List" in the route table 4, field 5 of the "Life Time" ₆ stores the survival time of the route. Thus, after this the entry, the "Life Time" field 5 of ₆ based on the stored survival time survival whether is managed, if the survival time without being used has passed from the route table 4 Deleted.

  Thereafter, similar processing is performed in each of the corresponding nodes A ′ to E ′ in the ad hoc network system 1, and the route request message 2 is eventually transmitted to the node D ′ which is the route request message transmission destination node. (FIG. 12B).

  At this time, each of the nodes A ′ to E ′ that have received the route request message 2 checks the route request message ID (“RREQ ID” in FIG. 13) of the route request message 2 in order to prevent double reception. If the route request message 2 having the same route request message ID has been received, the route request message 2 is discarded.

Note that a plurality of route request messages 2 may reach the node D ′ through different routes. At this time, the node D ′ gives priority to the one that arrives first, and discards the one that arrives after the second. It is made to do . As a result, a unique route from the node S ′, which is the transmission source of the route request message, to the node D ′, which is the transmission destination, can be created in both directions.

  On the other hand, the node D ′ that has received the route request message 2 creates a route reply message (RREP: Route Reply) 6 as shown in FIG. Unicast to E '.

The route response message 6 includes fields of “Type”, “Flag”, “Reserved”, “Prefix Sz”, “Hop Count”, “Destination Address”, “Destination Sequence Number”, “Originator Address”, and “Lifetime”. 7 _{1-7 9} are composed of, (in the case of route reply message "2") message type field ₇₁ of the "type" flag for the field 7 ₂ for various communication control "flag", field 7 ₄ to the subnet address "Prefix Sz" field 7 ₅ the number of hops of the "hop count" (initial value is "0") respectively.

The "Destination Address" in the route reply message 6, each field 7 _{6-7 8} "Destination Sequence Number" and "Originator Address", "Originator Address" in such route request message 2, respectively, "Originator Sequence Number" or " Data in each field 3 ₈ , 3 ₉ , 3 ₆ of “Destination Address” is copied.

And this route node receives a response message 6 C', E'the route reply addressed to themselves based on the destination of the route reply message 6 described in the field 7 ₆ in "Destination Address" of the route reply message 6 it is determined whether the message 6, the route reply message 6 in terms of increased "1" the number of hops stored in the field 7 ₅ "hop count" when not addressed to itself, the route request message node set as reverse path during second transfer (route table 4 for node S'( "Next Hop" field 5 ₄ in the described nodes of FIG. 14)) A'~C', unicast E' To do.

  At this time, the nodes A ′ to C ′, E ′, and S ′ investigate whether or not the address of the node D that is the transmission source of the route response message 6 exists in its route table 4 and does not exist. In this case, the reverse route entry to the node D is inserted into the route table 4 in the same manner as described above with reference to FIG.

Thus, thereafter, the same processing is sequentially performed in the corresponding nodes A ′ to C ′ and E ′, so that the route response message 6 eventually reaches the node S ′ that is the transmission source of the route request message 2. Is transmitted (FIG. 12C). When the node S ′ receives this route response message 6, the route discovery process ends.

In this way, in AODV, each of the nodes A ′ to E ′ and S ′ discovers and sets a communication path with the communication destination node.
US Patent Application Publication No. 2002/0049561

  By the way, although the above-mentioned on-demand method, the table driving method, and the hybrid method, which are currently proposed as routing protocols for ad hoc networks, have different ways of creating a route, each of these methods has one destination on the route table. This is common in that it only has one route (next hop) for the network, so even if there is a request to use a different route when a failure occurs in communication between nodes. It is necessary to wait for a new route to be created in some way.

  In this case, in the on-demand method, since a new route is started after detecting the occurrence of a failure, the overhead and time until recovery is large. In the table driving method, since route information is always exchanged by a routing protocol, it is considered to be relatively resistant to failures, but there is a problem of overhead due to transmission and reception of information at all times. In practice, considering an environment where mobile devices are connected via an ad hoc network, it is not a good idea to always exchange route information from the viewpoint of power consumption. On the other hand, if the cycle of updating the route table is long, there is a problem that a sudden failure cannot be dealt with.

  For example, in the above-described AODV protocol, when communication between nodes fails and communication is disconnected, a message called “Local Repair” that transmits a message for requesting rediscovery of a route from both nodes is newly added. Although a route is to be created, only one route can be created at the same time due to the AODV protocol mechanism. Therefore, in principle, a new route is created only after disconnection even if a link failure occurs. If a route can be created even by local repair, it will be an effective method for real-time communication that requires immediacy.

  As described above, in general ad hoc routing, there is only a single route for one destination in the route table, so that a countermeasure for a failure in communication between nodes is not sufficient. AODV, which is a typical on-demand routing protocol, is difficult to hold a plurality of routes at the same time, and does not sufficiently satisfy the demand for failure countermeasures.

The present invention has been made in view of the above points, and intends to propose a highly reliable communication terminal apparatus, a control method therefor, and a program.

In order to solve this problem, in the present invention, in the communication terminal device, the control method thereof, and the program, the route request message transmitted from the first communication terminal to the second communication terminal as the transmission destination or the second communication terminal Communication terminal device that relays a message that is a route response message to which the first communication terminal is the destination and that has message identification information attached, and creates a route between the communication terminals based on the message The message identification information of the message received in the past is stored in the history storage means, the message identification information of the received message is already stored in the history storage means, and the message If terminal identification information that identifies your communication terminal is attached, discard the message In other cases, the first communication terminal or the second communication terminal is recorded by recording a route having the transmission source of the message as a transmission destination and the transfer source of the message as a transfer destination in a predetermined route list. Multiple message paths are created, the message identification information attached to the message is stored in the history storage means, and if the message destination is not its own terminal device, its own terminal identification information is attached to the message. Transfer and store a plurality of created routes, and set one route from among the plurality of routes as the communication route to the first communication terminal or the second communication terminal, while the communication The route is switched to another route among a plurality of routes as required.

As a result, according to this communication terminal device and its control method and program, even if a message with the same message identification information has been received in the past, if its own terminal identification information is not attached, Since it can be determined that the message has been routed differently from the message received in the past, multiple routes can be generated while avoiding loops, and even when a communication failure occurs, the route can be switched quickly to another route. Stable communication can be performed.

In the present invention, in the communication terminal device and the control method and program thereof,
A transmission means for adding a message identification information to a route request message that is sent to a desired first communication terminal as a transmission destination, and a transmission source that represents a response from the first communication terminal and that is a transmission destination In the second communication terminal for transferring a message composed of a route response message or a route request message with message identification information attached thereto, a history in which the message identification information of the received message stores the message identification information of the message received in the past If the message is already stored in the storage means and the terminal identification information for identifying the second communication terminal is attached to the message, the message is discarded; otherwise, the message A route having the transmission source as a transmission destination and the transfer source of the message as a transfer destination is recorded in a predetermined route list. A plurality of routes to the first communication terminal or the own communication terminal are created, the message identification information attached to the message is stored in the history storage means, and the terminal identification of the second terminal device is further added to the message As a result of the transfer with the information attached, a plurality of routes to the first communication terminal are created by receiving duplicate route response messages from the first communication terminal, and the created routes are stored. and, together with the managed set one path from among the plurality of routes as a communication route, in communication with the first communication terminal via the set communication path, a plurality of paths as required the communication path I switched to another route.

As a result, according to this communication terminal device and its control method and program, even if a message with the same message identification information has been received in the past, if its own terminal identification information is not attached, Since it can be determined that the message has been routed differently from the message received in the past, multiple routes can be generated while avoiding loops, and even when a communication failure occurs, the route can be switched quickly to another route. Stable communication can be performed.

Furthermore, in the present invention, in the communication terminal device, its control method, and program, the route request message transmitted from the first communication terminal, transmitted via the second communication terminal, and attached with message identification information is added. On the basis of this, in the communication terminal device that creates a route to the first communication terminal, when the route request message is received by the second communication terminal , the message identification information of the route request message indicates the second communication. The terminal is already stored in the history storage means for storing the message identification information of the route request message received by the terminal in the past, and the terminal identification information for identifying the second communication terminal is attached to the route request message. The route request message is discarded, otherwise the source of the route request message A route having the transmission destination as the transmission destination and the transfer destination of the message is recorded in a predetermined route list, and the message identification information attached to the route request message is stored in the history storage unit. As a result of being transferred with the terminal identification information of the second communication terminal, the route request message that has been transferred is received redundantly, and the first communication terminal is received based on the redundantly received route request message A plurality of routes are created, and the created routes are stored and managed, and one route is set as a communication route to the first communication terminal from the plurality of routes. Switch to another route among multiple routes as necessary.

As a result, according to this communication terminal device and its control method and program, even if a message with the same message identification information has been received in the past, if its own terminal identification information is not attached, Since it can be determined that the message has been routed differently from the message received in the past, multiple routes can be generated while avoiding loops, and even when a communication failure occurs, the route can be switched quickly to another route. Stable communication can be performed.

According to the present invention, even if a message with the same message identification information has been received in the past, if the terminal identification information has not been added, the message has passed through a different path from the message received in the past. Can be judged. As a result, a plurality of routes can be generated while avoiding a loop, and even when a communication failure occurs, a stable communication can be performed by quickly switching to another route, so a highly reliable communication terminal An apparatus, a control method thereof, and a program can be realized.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of ad hoc network system according to the present embodiment (1-1) Schematic configuration of ad hoc network system according to the present embodiment In FIG. 1, reference numeral 10 denotes an ad hoc network system according to the present embodiment as a whole. FIG. 12 except that A to E and S each create a plurality of paths at the start of data communication, and switch to use these paths when a communication failure occurs during subsequent data communication. The configuration is almost the same as that of the ad hoc network system 1 described above.

  That is, in the case of this ad hoc network system 10, for example, when data is transmitted from the node S to the node D, the node S broadcasts a route request message 20 (FIG. 3) having the node D as a transmission destination.

  At this time, each of the nodes A to E other than the node S receives the route request message 20 transmitted via a different route in duplicate while setting the reverse route, and broadcasts them sequentially. As a result, a plurality of routes from the node S to the node D are created. At this time, each of the nodes A to E and S sets the priority order according to a predetermined criterion and manages the created routes in the route table 30 (FIG. 7).

  On the other hand, the node D receiving the route request message 20 unicasts (that is, multicasts) the route response message 23 (FIG. 6) having the node S as the transmission destination for each created route. Then, each of the nodes A to C, E, and S other than the node D sets a reverse route to the node D, respectively, in the route response message 23 transmitted in the reverse direction to the route set when the route request message 20 is transferred. However, these are received redundantly, and these are unicast to each route to the node S set when the route request message 20 is transferred. As a result, a plurality of paths from the node D to the node S are created. At this time, each of the nodes A to E and S manages the created route in the route table 30 by setting priority according to a predetermined standard.

  Then, each of the nodes A to E starts transmission of data from the node S, and when the data is transmitted, the node A to E selects the route with the highest priority from the plurality of routes managed in its own route table 30. One is selected and data is transmitted to the corresponding nodes A to E. As a result, the data transmitted from the node S is transmitted to the node D through a route most suitable for a predetermined standard.

  On the other hand, when a communication failure occurs during the transmission of such data, the nodes A to E and S in which the communication failure has occurred are currently used from a plurality of routes managed in its own route table 30. The route having the next highest priority is selected after the route, the used route is switched to the route, and data is transmitted to the corresponding nodes A to E.

  Then, when data is transmitted, the nodes A to E selected as the new route select one route having the highest priority from a plurality of routes managed in its route table, and cope with it. While the data is transmitted to the nodes A to E, the subsequent nodes A to E transfer the data sequentially transmitted from the previous nodes A to E to the next hop nodes A to E in the same manner.

  In this way, in this ad hoc network system 10, when a communication failure or the like occurs, the communication is continued by switching to another route among a plurality of routes created in advance, so that a sudden communication failure occurs. It has been made so that it can be dealt with in practice.

  FIG. 2 shows a hardware configuration of the communication function block 11 installed in each of the nodes A to E and S.

  As is apparent from FIG. 2, the communication function block 11 of each of the nodes A to E and S includes a CPU (Central Processing Unit) 12, a ROM (Read Only Memory) 13 in which various programs are stored, and a work memory of the CPU 12. A RAM (Random Access Memory) 14, a communication processing unit 15 that performs wireless communication with other nodes A to E, and S and a timer 16 are connected to each other via a bus 17.

  The CPU 12 executes various processes as described above and below based on a program stored in the ROM 13, and when necessary, various messages such as a route request message 20 or a route response message 23, and various types of AV (Audio Video) data. Data is transmitted to the other nodes A to E and S via the communication processing unit 15.

  Further, the CPU 12 creates a route table 30 as described later based on the route request message 20 from the other nodes A to E and S received via the communication processing unit 15, and stores and stores this in the RAM 14. On the other hand, the lifetime of the route entry to each of the nodes A to E and S registered in the route table 30 is managed based on the count value of the timer 16.

(1-2) Specific processing contents of each node in the route discovery process Next, specific processing contents of the nodes A to E and S in this route discovery process will be described.

As described above, in the ad hoc network system 10, each of the nodes A to E receives the route request message 20 in duplicate, thereby creating a plurality of routes to the node S that is the transmission source of the route request message 20.

  However, when the nodes A to E receive the same route request message transmitted via different routes in this way, the route request message 20 loops and relays the nodes A to E. May receive the same route request message 20 many times.

  Therefore, in this ad hoc network system 10, as shown in FIG. 3 in which the same reference numerals are given to the corresponding parts to FIG. 13, the conventional route request message 2 (FIG. 13) is extended to the field (Relay Node Address # 1 to #n) 22 are provided, and nodes A to E relaying the route request message 20 sequentially expand their own field 22 and sequentially describe their own addresses in the expanded field 22. Has been made.

  When the nodes A to E receive the route request message 20, they check the route request message ID (RREQ ID), have received a route request message to which the same route request message ID has been assigned in the past, and If the relay node list 21 has its own address, the route request message 20 is discarded.

  As a result, in this ad hoc network system 10, it is possible to effectively and reliably prevent the route request message 20 from looping between the nodes A to E. Thus, each of the nodes A to E establishes a plurality of routes to the node S. It is designed to be properly created.

Here, such processing is performed under the control of the CPU 12 according to the route request message reception processing procedure RT1 shown in FIG. In practice, when receiving the route request message 20, the CPU 12 of each of the nodes A to E starts this route request message reception processing procedure RT1 at step SP0, and at the subsequent step SP1, "RREQ ID" of the route request message 20 reads field ₃₅ is stored in the route request message ID, and stores it in the RAM14 as the reception history of the route request message 20, the received based on the history, the same route request message ID route request was granted message It is determined whether 20 has been received in the past.

If the CPU 12 obtains a negative result in step SP1, it proceeds to step SP5. If it obtains an affirmative result, it proceeds to step SP2, and its own address exists in the relay node list 21 of the route request message 20. Judge whether to do.

  Here, obtaining a positive result in step SP2 means that the nodes A to E have relayed the route request message 20 itself in the past, and thus the CPU proceeds to step SP3 and proceeds to step SP3. The route request message 20 is discarded, and then the process proceeds to step SP9 to end the route request message reception processing procedure RT1.

On the other hand, obtaining a negative result in step SP2 means that the nodes A to E have relayed the route request message 20 having the same route request message ID transmitted via other routes in the past. However, this means that the route request message 20 itself has not been relayed, and thus the CPU 12 proceeds to step SP4 and adds its own address to the relay node list 21 of the route request message 20.

  Further, the CPU 12 thereafter proceeds to step SP5 and newly sets an entry of the reverse route of the route through which the route request message 20 has passed as a route to the node S in accordance with a route entry insertion processing procedure RT2 (FIG. 8) described later. It is inserted into its own route table 30 (FIG. 7).

Further CPU12 proceeds to step SP6 thereafter, the route request message 20 based on the destination of the "Destination Address" field 3 ₆ the route request message 20 described in the, the route request message 20 is addressed to itself It is judged whether it is a thing.

CPU12 then obtains a negative result in step SP6, the process proceeds to step SP8, the hop count stored in the field 3 ₄ of the "Hop Count" of the route request message 20 in terms of increased "1", The route request message 20 is broadcasted, and then the process proceeds to step SP9 to end the route request message reception processing procedure RT1.

On the other hand, when the CPU 12 obtains a positive result in step SP6, the CPU 12 proceeds to step SP7 to generate a route response message 23 (FIG. 6) for the route request message 20, and responds based on its own route table 30. After unicasting to nodes C and E, the process proceeds to step SP9, and this route request message reception processing procedure RT1 is terminated.

In this embodiment, in step SP7 of the route request message reception processing procedure RT1, the CPU 12 uses the same ID (hereinafter referred to as route response message ID) as a response to the route request message 20 having the same route request message ID. A route response message 23 to which (referred to as (RREP ID)) is added is generated.

  That is, the route response message is normally transmitted by unicast so as to pass through the reverse route set at the time of transmission of the route request message. However, since there are a plurality of reverse routes in this embodiment, the route response message The message 23 is copied by the number of reverse paths and transmitted by multicast.

  In this case, for example, as illustrated in FIG. 5, when the route request message 20 transmitted from the node S reaches the node D via three routes (first to third routes RU1 to RU3), the node D As a response to the route request message 20 reached via the first route RU1, it reached the node C as a response to the route request message 20 reached via the second route RU2, and reached the node E as a response to the route request message 20 reached via the third route RU3. As a response to the route request message 20, the route response message 23 is transmitted to each node E by unicast. At this time, the node E sets a reverse route with the node D as the destination (Destination Address) twice. Become. A similar situation also occurs in node A and node S.

  Therefore, in this ad hoc network system 10, the conventional route response message 6 (FIG. 15) is expanded and the field 24 of “RREP ID” is extended as shown in FIG. When the node D receiving the route request message 20 returns the route response message 23, a route response message ID similar to the route request message ID in the route request message is stored in this field 24.

  Then, the nodes A to C, E, and S that have received the route response message 23 have received the route response message 23 with the same route response message ID in the past, and the backward route to the node S has already been received in the route table 30. The route response message 23 is discarded, otherwise the route to the node D that has transmitted the route response message 23 according to the route entry insertion processing procedure RT2 described later with reference to FIG. Insert into the route table 30.

  In this way, in this ad hoc network system 10, it is possible to effectively prevent multiple settings of reverse paths to the node (node D) that has transmitted the path response message 23 that may occur when a plurality of paths are created, and such redundancy. Can be surely prevented.

(1-3) Management Method of Multiple Routes in Each Node A to E, S As described above, in this ad hoc network system 10, each node A to E, S is a data transmission source at the start of data communication. A plurality of paths between the node S and the node D that is the transmission destination of the data are created. Each of the nodes A to E and S manages these created paths by using the path table 30 shown in FIG. 7 in which the same reference numerals are assigned to the corresponding parts in FIG.

The route table 30 includes fields 5 ₁ , 5 ₂ , 31 _{1 to} 31 of “Destination Address”, “Destination Sequence Number”, “Minimum Hop Count”, “Maximum Hop Count”, “Route List”, and “Precursor List”. ₃ , 5, ₅ , and created in the “Route List” field 31 ₃ corresponding to each route to the destination nodes A to E and S discovered by the route discovery process as described above 1 or a plurality of route lists 32 are stored, and the fields 31 ₁ and 31 ₂ of “Minimum Hop Count” and “Maximum Hop Count” have the most hop counts among the routes discovered by the route discovery process. The number of hops of the route with the smallest number of routes or the number of hops of the route with the largest number of hops is stored.

On the other hand, the route list 32 has “Hop Count”, “Next Hop”, “Life Time”, and “Link Quality” fields 33 ₁ to 33 ₄ , and the “Hop Count” field 33 ₁ transmits in the route. previous node a-E, the number of hops to S, the next hop in the field 33 ₂ the path of the "next hop", "Life time" field 33 survival time of ₃ to the route (next hop) of the "Link Quality" quality of the path to the field 33 ₄ are stored. And this route list 32 is stored in a field ₃₁₃ of the created each time a new route is found corresponding route table 30 by "Route List".

In this case, the field 33 ₄ of "Link Quality" of each route list 32, as the quality of the route, information such as radio wave condition and packet error rate of the path is described. Information on the quality of the route is sequentially updated each time the route is used.

And each route list 32, whether the survival by the "Life Time" survival time described in the field 33 ₃ of the management, when the survival time without corresponding path is used has elapsed, the path list 32 is automatically deleted from the route table 30.

Furthermore each route list 32 is provided with a field 33 ₅ of the "Next the List", a pointer corresponding to the path list corresponding to the route having the next priority path 32 is written into this field 33 ₅ The Thus, the route list 32 can be searched according to the priority order based on this pointer when necessary.

  In this embodiment, since routes that can reach the destination nodes A to E and D with the shortest hop are generally considered to have the best performance, the route priorities are assigned in ascending order of the number of hops. It is made like that.

  Here, the CPU 12 of each of the nodes A to E and S executes the processing for inserting a new route entry into the route table 30 as described above according to the route entry insertion processing procedure RT2 shown in FIG.

That is, when receiving the route request message 20 (FIG. 3) or the route response message 23 (FIG. 6), the CPU 12 starts this route entry insertion processing procedure RT2 in step SP10, and in the subsequent step SP11, stores it in its route table 30. field 3 8 "Originator Address" of the route request message 20 _(FIG. 3) or the route reply message fields 7 8 "Originator Address" 23 _(FIG. 6) the described in the route request message 20 or the route reply message 23 It is determined whether or not the address ( Originator Address) of the node S or node D, which is the transmission source node, exists.

  To obtain a negative result in this step SP11 means that the route to the node S or node D is not yet registered in the own route table 30 in the nodes A to E and S, and thus the CPU 12 at this time, Proceeding to step SP12, normal route entry insertion processing is executed.

Specifically, the CPU 12 sets the “Originator Address” and “Originator Sequence Number” of the route request message 20 or the route response message 23 to the corresponding “Destination Address” or “Destination Sequence Number” fields 5 ₁ , 5, respectively. copy ₂ copies respectively to "Hop Count" of the route request message 20 or the route reply message 23 to each of the fields 31 _1, 31 ₂ of the "Minimum Hop Count" and "Maximum Hop Count" of the route table 30.

The CPU12, copy the "Hop Count" of the route request message 20 or the route reply message 23 to field 33 ₁ of the "Hop Count" route list 32, the route request message 20 or the route reply message 23 is stored adjacent nodes A~E that has transmitted the route request message 20 included in the header of the packet, copies the address of the S field 33 ₂ of the "Next Hop" path list 32, the further survival predetermined time " while described in the field 33 ₃ of Lifetime "field quality of the radio wave conditions and packet error rate of the detected that route based on the reception states of the route request message 20 or the route reply message 23 or the like at that time the" Link quality " 33 ₄ so as to describe a path motion list 32, which in the route table 30 "Ro is stored in the field 31 ₃ of ute List ".

  When the CPU 12 registers the route to the node S or the node D in the route table 30 by the normal route entry insertion processing in step SP12 in this way, the CPU 12 thereafter proceeds to step SP23 and proceeds to this route entry insertion processing procedure RT2. Exit.

  On the other hand, obtaining a positive result in step SP11 means that one or more routes to the node S or the node D, which is the transmission source of the route request message 20 or the route response message 23, are already in the route table 30 of itself. In this case, the CPU 21 proceeds to step SP13 and searches the route table 30 to search for the route request message 20 or the route response message 23. It is determined whether or not there is a corresponding route list 32 having S as “Next Hop”.

  If the CPU 12 obtains a positive result in step SP13, it proceeds to step SP21. If it obtains a negative result, it proceeds to step SP14, and the maximum number of route lists that can be registered for one “Destination Address”. Determine if it is a number. If the CPU 12 obtains a negative result in step SP14, it proceeds to step SP16, and if it obtains an affirmative result, it proceeds to step SP15 to temporally select from the route list 32 corresponding to the “Destination Address”. After deleting the oldest route list (that is, the time most elapsed after creation), the process proceeds to step SP16.

In step SP16, the CPU 12 determines that the number of hops described in the “Hop Count” fields 3 ₄ (FIG. 3) and 7 ₄ (FIG. 6) of the route request message 20 or the route response message 23 is in the route table 30. to determine the corresponding not "maximum hop count" or field 31 ₂ hop count described in (maximum number of hops) is greater than the. CPU12 then proceeds to step SP18 upon obtaining a negative result in this step SP16, it proceeds to step SP17 upon obtaining a positive result, described in field ₃₁₂ of the corresponding "Maximum Hop Count" of the route table 30 Step SP18 after rewriting the number of hops set to the number of hops described in the “Hop Count” fields 3 ₄ (FIG. 3), 7 ₄ (FIG. 6) of the route request message 20 or route response message 23 Proceed to

Further, in step SP18, the CPU 12 determines that the number of hops described in the “Hop Count” fields 3 ₄ (FIG. 3) and 7 ₄ (FIG. 6) of the route request message 20 or the route response message 23 is in the route table 30. It determines whether less than the corresponding "minimum hop count" field 31 hop count described in ₁ (minimum number of hops). CPU12 then proceeds to step SP20 upon obtaining a negative result in this step SP18, it proceeds to step SP19 upon obtaining a positive result, described in field 31 ₁ of the "Minimum Hop Count" corresponding route table 30 Step SP20 after rewriting the number of hops set to the number of hops described in the “Hop Count” fields 3 ₄ (FIG. 3) and 7 ₄ (FIG. 6) of the route request message 20 or route response message 23 Proceed to

Subsequently CPU12 at step SP20, to create a route list 32 corresponding to the route in a manner similar to that described above for step SP 12, this path table 30 corresponding to registered in the field ₃₁₃ of the "Route List" . At this time, the CPU 12 determines the priority of the route list 32 of the same “Destination Address” based on the “Hop Count” of each route list 32, and according to this, the “Next List” field of the corresponding route list 32 33 _5, rewrites optionally a pointer to the route list 32 corresponding to the path with the next priority.

  Next, the CPU 12 proceeds to step SP21 to update “Lifetime” of the route list 32 newly inserted in step SP20, and then proceeds to step SP22 to detect “Link Quality” of the route list 32 at that time. The route information is updated according to the quality of the corresponding route, and the process proceeds to step SP23 to end the route entry insertion processing procedure RT2.

  In this way, each of the nodes A to E and S can manage a new route in its route table 30.

(1-4) Specific Processing Contents of Each Node A to E, S Regarding Data Communication The node S that is the transmission source of the route request message 20 sends this route request from the node D that is the transmission destination of the route request message 20. When the route response message 23 for the message 20 is received, the route from the node S to the node D is set.

In the present embodiment, the node S receives the route response messages 23 corresponding to the number of routes set at this time, but the route through which the route response message 23 received first has a small number of hops and quality. The route is not necessarily high.

  Therefore, in this ad hoc network system 10, the node S that is the transmission source of the route request message 20 has passed a predetermined time after receiving the first route response message 23 or a predetermined number of predetermined times. Waiting for the reception of the route response message 23, the route having the smallest number of hops is selected from the routes each route response message 23 has received, and the node that is the destination of the route request message 23 through the route Communication with D is started.

  At this time, the node S determines based on the route response message ID included in the route response message 23 whether or not the route response message 23 reached at that time is transmitted from the same node D at the same time. Thus, it is possible to prevent an incorrect route from being selected.

Here, such processing in the node S is performed under the control of the CPU 12 (FIG. 2) according to the route response message reception processing procedure RT3 shown in FIG. That is, when the CPU 12 of the node S receives the first route response message 23 after transmitting the route request message 20, the CPU 12 of the node S starts this route response message reception processing procedure RT3 in step SP30, and in the subsequent step SP31 , the first route response message 23 is received. It is determined whether or not a predetermined time has elapsed since the reception of.

CPU12 then this proceeds obtains a negative result in step SP31 to step SP32 to determine whether or not it has received the new route reply message 23, the flow returns to step SP31 upon obtaining a negative result in this step SP32.

  On the other hand, if the CPU 12 obtains a positive result in step SP32, it proceeds to step SP33 and determines whether or not a predetermined number of route response messages 23 including the first received route response message 23 have been received.

If the CPU 12 obtains a negative result in step SP33, it returns to step SP31 , and then repeats the loop of step SP31- SP32-SP33- SP31 until a positive result is obtained in step SP32 or step SP33.

When the CPU 12 eventually receives the first route response message 23 and a predetermined time elapses or receives a predetermined number of route response messages 23, the CPU 12 obtains an affirmative result in step SP32 or step SP33. Then, the route response message reception processing procedure RT3 is terminated, and thereafter, the “Next Hop” field 33 ₂ (in the route list 32 having the highest priority registered in the corresponding “Route List” of the route table 30 ( In FIG. 7), unicasting of data is started to nodes A and B whose addresses are registered.

On the other hand, when the transmission of data from the node S is started in this manner, the nodes A to E that have transmitted this data search their own route table 30 and transmit the data to the destination node (that is, the node). D) is detected, and is registered in the field 33 ₂ (FIG. 7) of “Next Hop” in the route list 32 of the route with the highest priority from the corresponding route list 32 detected thereby. The data is unicast to the obtained nodes A to E.

  For example, when data is transmitted from the node S to the node A in the state where the route setting is completed in each of the nodes A to E and S as shown in FIG. 10, the node A sends the node D to the destination (Destination Address). The route list 32 includes the route list 32 that sets the node C as “Next Hop” and the route list 32 that sets the node B as “Next Hop”. The node C is set as “Next Hop”. Since the route list 32 has a smaller number of hops, a higher priority is set. Therefore, the node A transfers the data transmitted from the node S to the node C by unicast.

Similarly, the node C has, as a route list 32 having the node D as a transmission destination, a route list having the node D as “Next Hop” and a route list having the node E as “Next Hop”. The route list 32 having the node D as “Next Hop” has a lower priority because it has a smaller number of hops. Therefore, the node C transfers the data transmitted from the node A to the node D by unicast.

  In this example, the node S includes a route list 32 having the node D as a transmission destination, a route list 32 having the node A as “Next Hop”, and a route list 32 having the node B as “Next Hop”. Each route list 32 has the same “Hop Count”, but in such a case, the node S has a predetermined element other than the number of hops of the route, for example, the quality of the route (Link Quality). ) And the like are taken into consideration to select the optimum route.

  On the other hand, after a communication between the node S and the node D is started, if a communication failure occurs between any of the nodes A to E and S configuring a route through which the data passes, the transmitting side nodes A to C, E and S In the meantime, based on the route table 30 owned by itself, from among several route lists 32 included in the entry having the node D as the data transmission destination as “Destination Address”, it is used until that time. The route list 32 of the route having the next priority of the route is newly selected, and thereafter, data is transmitted to the nodes A to E described as “Next Hop” in the route list 32.

  For example, in the example of FIG. 10, when a communication failure occurs between the node A and the node C, the node A selects a route via the node B to which the next priority order of the route via the node C is given, Data is transferred to the node B described in “Next Hop” in the route list 32.

Here, such processing in each of the nodes A to C, E, and S is performed under the control of the CPU 12 according to the communication processing procedure RT4 shown in FIG. That is, the CPU 12 of each of the nodes A to C, E, and S starts the transmission of data or starts the communication processing procedure RT4 at step SP40 when the data is transmitted, and the transmitted data at the subsequent step SP41. Are unicast to the nodes A to E described in the field 33 ₂ (FIG. 7) of the “Next Hop” in the route list 32 of the route with the highest priority.

  Subsequently, the CPU 12 proceeds to step SP42, and determines whether or not a communication failure has occurred with the nodes A to E based on the radio wave conditions with the nodes A to E of the communication counterpart.

  If the CPU 12 obtains a negative result in step SP42, the process proceeds to step SP43, and the data transmission source (node S) and transmission are transmitted according to the transmission status of data transmitted from the previous nodes A to C, E, and S. It is determined whether or not communication between the previous (node D) ends.

  If the CPU 12 obtains a negative result in step SP43, it returns to step SP41, and thereafter repeats the loop of step SP41-SP42-SP43-SP41 until a positive result is obtained in step SP42 or step SP43.

When the CPU 12 eventually obtains an affirmative result in step SP42, the CPU 12 proceeds to step SP44 and uses the pointer stored in the field 33 ₅ (FIG. 7) of the “Next List” of the route list 32 used up to that point. The route list 32 of the route having the next priority is searched for, the route list 32 to be used is switched to the route list 32, and then the process returns to step SP41. Thus, the CPU 12 thereafter unicasts data to the nodes A to E described in the “Next Hop” field 33 ₂ (FIG. 7) of the route list 32 selected in step SP44.

  If the CPU 12 obtains a positive result in step SP43 thereafter, the CPU 12 proceeds to step SP45 and ends the communication processing procedure RT4.

(3) Operation and effect of the present embodiment In the above configuration, the ad hoc network system 10 sets a plurality of paths in each of the nodes A to E and S at the start of data communication, and gives priority to the plurality of paths. Priorities are assigned, and when data is transmitted, communication is performed using the route with the highest priority.

  Therefore, in this ad hoc network system 10, when transmitting / receiving real-time stream data, for example, VoIP or moving images, even if a communication failure occurs between the nodes A to E and S, it is possible to quickly switch to another route and stabilize Communication can be performed.

  According to the above configuration, a plurality of paths are set in each of the nodes A to E and S at the start of data communication, and priorities are given to the plurality of paths. As a result of performing communication using the node, even when a communication failure occurs between the nodes A to E and S, it is possible to quickly switch to another route and perform stable communication, and thus high reliability. An ad hoc network system can be realized.

(4) Other Embodiments In the above-described embodiments, the present invention is applied to the ad hoc network system 10 of the AODV protocol that is widely used as an ad hoc routing protocol and the nodes A to E and S that constitute the same. However, the present invention is not limited to this, and includes a plurality of communication terminals, which are transmitted from the first communication terminal and transmitted to the third communication terminal via the second communication terminal. The second and third communication terminals create a route to the first communication terminal based on the received message, and various kinds of communication are performed between the first and third communication terminals via the created route. It can apply widely to the communication terminal device which comprises the communication system of the form, and the said communication system.

  In the above-described embodiment, the route creation means for creating a plurality of routes to the transmission source by receiving duplicate messages such as the route request message 20 (FIG. 3) and the route response message 23 (FIG. 6); The communication function of each of the nodes A to E and S having the functions of a path management means for storing and managing a plurality of created paths and a communication means for communicating with other nodes A to E and S Although the case where the block 11 is configured as shown in FIG. 2 has been described, the present invention is not limited to this, and various other configurations can be widely applied.

  Further, in the above-described embodiment, the case has been described in which the number of hops is applied as a criterion for setting the priority, and a high priority is set for a route with a small number of hops. However, the present invention is not limited to this. Alternatively, the quality of the route may be used as a standard, and as such a standard, various criteria may be widely applied depending on the purpose of use, for example, the number of hops and the quality of the route are determined in combination. Can do.

In this case, when priorities are set for routes based on matters other than the number of hops, “Minimum Hop Count” and “Maximum Hop” in the route table 30 (FIG. 7) are set in each of the nodes A to E and S. The minimum and maximum values of the reference among the created paths may be stored in the fields 31 ₁ and 31 ₂ of “Count”.

  Furthermore, in the above-described embodiment, the case where the priority order of a route is fixedly set according to the number of hops of the route has been described, but the present invention is not limited to this, and this criterion is not limited to the communication state or It may be changed dynamically based on the route quality such as the packet error rate and the priority order for each route may be reset accordingly.

  Further, in the above-described embodiment, a case has been described in which each of the nodes A to E and S manages a plurality of created entries for each route. However, the present invention is not limited to this, for example, Each entry of a plurality of routes may be tabulated and managed integrally. However, by listing each route as in the embodiment, there is an advantage that the processing when rearranging the route order according to the priority order becomes easy.

  In this case, in the above-described embodiment, the number of hops of the route, the next hop, the lifetime, the quality of the route, and a pointer to the next route list are held for each route as an entry of each route list 32. Although the case where it did so was described, this invention is not restricted to this, You may make it hold | maintain information other than these as information regarding the path | route in addition to or instead of these.

  Further, in the above-described embodiment, the format as shown in FIG. 3 is applied as the route request message 20, and the nodes A to C and E relaying the route request message 20 sequentially expand the field 22 of the relay node list 21. However, the description has been given of the case where its own address is described in the relay node list 21. However, the present invention is not limited to this, and the format of the route request message 20 may be other formats. Each of A to C and E relaying the route request message 20 may describe some identification information that can identify itself in the network system other than its own address.

  Further, in the above-described embodiment, the format as shown in FIG. 6 is applied as the route response message 23, and the address of the transmission source node is described in the field 24 of “RREP ID” of the route response message 23. Although the present invention is not limited to this, the format of the route response message 23 may be other formats, and the source of the route response message 23 may be other than its own address in the field 24 of “RREP ID”. You may make it describe some identification information which can identify self in the network system.

  The present invention can be applied to various network systems in addition to an ad hoc network system.

It is a conceptual diagram which shows the structure of the ad hoc network system by this Embodiment. It is a block diagram which shows the structure of the communication function block in each node. It is a conceptual diagram which shows the structure of the route request message by this Embodiment. It is a flowchart which shows a route request message reception processing procedure. It is a conceptual diagram with which it uses for description when a several path | route is created from the node S to the node D. FIG. It is a conceptual diagram which shows the structure of the route response message by this Embodiment. It is a conceptual diagram which shows the structure of the routing table by this Embodiment. It is a flowchart which shows a route entry insertion processing procedure. It is a flowchart which shows a route response message reception process procedure. It is a conceptual diagram which shows the state of the routing table in each node. It is a flowchart which shows a communication processing procedure. It is a conceptual diagram with which it uses for description of the route creation in the conventional ad hoc network system. It is a conceptual diagram which shows the structure of the conventional route request message. It is a conceptual diagram which shows the structure of the conventional route table. It is a conceptual diagram which shows the structure of the conventional path | route response message.

Explanation of symbols

  10: Ad hoc network system, 12: CPU, 20: Route request message, 21 ... Relay node list, 22, 24 ... Field, 23 ... Route response message, 30 ... Route table, 32 ... Route list.

Claims (16)

A message composed of a route request message transmitted from the first communication terminal to the second communication terminal as a transmission destination or a response message from the second communication terminal that represents the response from the second communication terminal and that has the first communication terminal as the transmission destination. In a communication terminal device that relays a message with identification information and creates a path between communication terminals based on the message,
Receiving means for receiving the message in duplicate;
History storage means for storing the message identification information of the message received in the past;
When the message identification information of the received message is already stored in the history storage means, and the terminal identification information for identifying the communication terminal of the message is attached to the message, the message is discarded, In other cases, the first communication terminal or the second communication terminal is recorded by recording, in a predetermined route list, a route in which the transmission source of the message is the transmission destination and the transfer source of the message is the transfer destination. A plurality of routes to the message, the message identification information attached to the message is stored in the history storage means, and if the destination of the message is not its own terminal device, the terminal identification information of the message A route creation means for forwarding with
Route management means for storing and managing a plurality of the routes created by the route creation means,
The route management means is
One of the plurality of routes is set as the communication route to the first communication terminal or the second communication terminal, and the communication route is set to another of the plurality of routes as necessary. A communication terminal device for switching to the above route. The route creation means
When transferring the message, the message is transferred to a plurality of transferable communication terminals excluding the transfer source of the message.
The communication terminal device according to claim 1. The route management means is
The communication terminal device according to claim 1, wherein a priority order is set for each of the created routes based on a predetermined criterion, and the route having a higher priority order is preferentially set as the communication route. The route management means is
The communication terminal device according to claim 3, wherein the reference is dynamically changed according to a communication status of the route, and the priority order for each of the created routes is reset. The route management means is
The communication terminal device according to claim 1, wherein the route that is not used for a predetermined time is deleted from the created routes. The route management means is
The communication terminal device according to claim 1, wherein when the created route exceeds a predetermined maximum number, the route is deleted in order from the oldest route. A message composed of a route request message transmitted from the first communication terminal to the second communication terminal as a transmission destination or a response message from the second communication terminal that represents the response from the second communication terminal and that has the first communication terminal as the transmission destination. In a method for controlling a communication terminal apparatus that relays a message with identification information and creates a path between communication terminals based on the message,
A receiving step for receiving the message in duplicate;
The message identification information of the received message is already stored in the history storage means for storing the message identification information of the message received in the past, and the terminal identification information for identifying the own communication terminal is included in the message. If the message is attached, the message is discarded; otherwise, the route having the message source as the destination and the message transfer source as the destination is recorded in a predetermined route list. together to create multiple above route to the first communication terminal or the second communication terminal, the message identification information attached to the message is stored in the history storage means, further send messages self by A route creation step for transferring the message with its own terminal identification information if it is not a terminal device of
A route management step for storing and managing the plurality of created routes, and
In the above route management step,
One of the plurality of routes is set as the communication route to the first communication terminal or the second communication terminal, and the communication route is set to another of the plurality of routes as necessary. A control method for a communication terminal device for switching to the above route. A message composed of a route request message transmitted from the first communication terminal to the second communication terminal as a transmission destination or a response message from the second communication terminal that represents the response from the second communication terminal and that has the first communication terminal as the transmission destination. In a program for controlling a communication terminal device that relays a message with identification information and creates a path between communication terminals based on the message,
A receiving step for receiving the message in duplicate;
The message identification information of the received message is already stored in the history storage means for storing the message identification information of the message received in the past, and the terminal identification information for identifying the own communication terminal is included in the message. If the message is attached, the message is discarded; otherwise, the route having the message source as the destination and the message transfer source as the destination is recorded in a predetermined route list. together to create multiple above route to the first communication terminal or the second communication terminal, the message identification information attached to the message is stored in the history storage means, further send messages self by A route creation step for transferring the message with its own terminal identification information if it is not a terminal device of
While storing and managing the plurality of created routes, one route is set from the plurality of routes as a communication route to the first communication terminal or the second communication terminal , A program for causing a computer to execute a process having a route management step of switching a communication route to another of the plurality of routes as necessary. A transmission means for adding a message identification information to a route request message to which a desired first communication terminal is a transmission destination;
A second communication that represents a response from the first communication terminal and that transmits a route response message to which the source of the route request message is a destination and a message including the route identification message or the route request message. In the terminal, the message identification information of the received message is already stored in the history storage means for storing the message identification information of the message received in the past, and the second communication terminal is identified in the message If terminal identification information is attached, the message is discarded; otherwise, a route whose destination is the source of the message and whose destination is the destination of the message is a predetermined route list. When a plurality of the routes to the first communication terminal or its own communication terminal are created by , The message identification information attached to the message is stored in the history storage means, and further, the terminal identification information of the second terminal device is attached to the message and transferred. As a result, the message from the first communication terminal by redundantly received the route reply message, a route creation means for creating multiple paths to the first communication terminal,
Storing and managing the plurality of routes created by the route creation means, and setting one route among the plurality of routes as a communication route;
Communication means for communicating with the first communication terminal through the set communication path,
The route management means is
A communication terminal apparatus that switches the communication path to another of the plurality of paths as necessary. The communication means is
The route creation means communicates with the first communication terminal after a predetermined time has elapsed after receiving the first route response message or after receiving a predetermined number of the route response messages from the first communication terminal. The communication terminal device according to claim 9 . A transmission step of transmitting a route request message with a desired first communication terminal as a transmission destination with message identification information for identifying the message ;
A second communication that represents a response from the first communication terminal and that transmits a route response message to which the source of the route request message is a destination and a message including the route identification message or the route request message. In the terminal, the message identification information of the received route request message is already stored in the history storage means for storing the message identification information of the route request message received in the past, and the second message is included in the route request message. If the terminal identification information for identifying the communication terminal is attached, the message is discarded, otherwise, the transmission source of the message is the transmission destination and the transfer source of the message is the transfer destination The route to the first communication terminal or its own communication terminal by recording the route in a predetermined route list As a result of creating a plurality of paths, the message identification information attached to the message is stored in the history storage means, and further, the terminal identification information of the second terminal device is attached to the message and transferred. a route creating step of creating multiple paths to the first communication terminal by receiving duplicate the route response message from the first communication terminal,
A communication step of setting one of the plurality of generated routes as a communication route and communicating with the first communication terminal through the communication route;
In the communication step above,
A method for controlling a communication terminal apparatus, wherein the communication path is switched to another path among the plurality of paths as necessary. A transmission step of transmitting a route request message with a desired first communication terminal as a transmission destination with message identification information for identifying the message ;
A second communication that represents a response from the first communication terminal and that transmits a route response message to which the source of the route request message is a destination and a message including the route identification message or the route request message. In the terminal, the message identification information of the received message is already stored in the history storage means for storing the message identification information of the message received in the past, and the second communication terminal is identified in the message If terminal identification information is attached, the message is discarded; otherwise, a route whose destination is the source of the message and whose destination is the destination of the message is a predetermined route list. When a plurality of the routes to the first communication terminal or its own communication terminal are created by , The message identification information attached to the message is stored in the history storage means, and further, the terminal identification information of the second terminal device is attached to the message and transferred. As a result, the message from the first communication terminal A route creation step of creating a plurality of routes to the first communication terminal by receiving the route response message in duplicate;
One of the created routes is set as a communication route, communicates with the first communication terminal through the communication route, and the communication route is selected from the plurality of routes as necessary. A program for causing a computer to execute a process having a communication step of switching to another path. A communication terminal that generates a route to the first communication terminal based on a route request message that is transmitted from the first communication terminal and transmitted through the second communication terminal and that has message identification information attached thereto. In the device
When the route request message is received by the second communication terminal, the message identification information of the route request message is the message identification information of the route request message received by the second communication terminal in the past. If it is already stored in the history storage means to be stored and terminal identification information for identifying the second communication terminal is attached to the route request message, the route request message is discarded. In this case, a route having the transmission source of the route request message as a transmission destination and the transfer source of the route request message as a transfer destination is recorded in a predetermined route list and the message identification attached to the route request message Information is stored in the history storage means, and terminal identification information of the second communication terminal is added to the route request message. Forwarded result, a receiving means for receiving a duplicate the route request message transferred,
Route creation means for creating a plurality of routes to the first communication terminal based on the route request message received in duplicate ;
Route management means for storing and managing a plurality of the routes created by the route creation means,
The route management means is
One of the created routes is set as a communication route to the first communication terminal, and the communication route is switched to another route among the plurality of routes as necessary. Communication terminal device. The communication terminal device according to claim 13 , further comprising response transmission means for transmitting a route response message for the route request message for each of the created routes. A communication terminal that generates a route to the first communication terminal based on a route request message that is transmitted from the first communication terminal and transmitted through the second communication terminal and that has message identification information attached thereto. In the device control method,
When the route request message is received by the second communication terminal, the message identification information of the route request message is the message identification information of the route request message received by the second communication terminal in the past. If it is already stored in the history storage means to be stored and terminal identification information for identifying the second communication terminal is attached to the route request message, the route request message is discarded. In this case, a route having the transmission source of the route request message as a transmission destination and the transfer source of the route request message as a transfer destination is recorded in a predetermined route list and the message identification attached to the route request message Information is stored in the history storage means, and terminal identification information of the second communication terminal is added to the route request message. Forwarded result, a receiving step of receiving duplicate the route request message transferred,
A route creation step for creating a plurality of routes to the first communication terminal based on the route request message received in duplicate ;
A route management step for storing and managing the plurality of created routes, and
In the above route management step,
One of the created routes is set as a communication route to the first communication terminal, and the communication route is switched to another route among the plurality of routes as necessary. A method for controlling a communication terminal device. A communication terminal that generates a route to the first communication terminal based on a route request message that is transmitted from the first communication terminal and transmitted through the second communication terminal and that has message identification information attached thereto. In a program for controlling a device,
When the route request message is received by the second communication terminal, the message identification information of the route request message is the message identification information of the route request message received by the second communication terminal in the past. If it is already stored in the history storage means to be stored and terminal identification information for identifying the second communication terminal is attached to the route request message, the route request message is discarded. In this case, a route having the transmission source of the route request message as a transmission destination and the transfer source of the route request message as a transfer destination is recorded in a predetermined route list and the message identification attached to the route request message Information is stored in the history storage means, and terminal identification information of the second communication terminal is added to the route request message. Forwarded result, a receiving step of receiving duplicate the route request message transferred,
A route creation step for creating a plurality of routes to the first communication terminal based on the route request message received in duplicate ;
The plurality of created routes are stored and managed, and one of the plurality of routes is set as a communication route to the first communication terminal, while the communication route is set as necessary. A program for causing a computer to execute processing including: a route management step of switching to another of the plurality of routes.

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