Route optimization method and agent apparatus

The present invention relates to a route optimization method and an agent device for optimizing the route of an IP packet in, for example, a communication system using Mobile IP.

When a mobile terminal device (abbreviated as Mobile Terminal, MT) having an IP (Internet Protocol) address moves across a network domain, the mobile terminal device communicates without interrupting a session. Mobile IP (Request For Comment 2002) of IETF (Internet Engineering Task Force) has been proposed as a method of keeping.

[0003] FIG. 30 is a diagram illustrating packet transmission with a conventional Mobile IP. In FIG. 30, 11 is a mobile terminal device to which an IP address in the home domain (hereinafter referred to as a home address) is fixedly assigned, and 13 is a home agent (Home) assigned to the home domain to which the mobile terminal device 11 belongs. Agent, abbreviated as HA). Reference numeral 41 denotes a remote terminal device which is a communication partner of the mobile terminal device 11. The remote terminal device 41 may be either a fixed terminal device or a mobile terminal device, and the remote terminal device is abbreviated as CN / MT (Corresponding Node / Mobile Terminal). Reference numeral 201 denotes an external agent (foreign agent, abbreviated as FA) that is located in the destination domain of the mobile terminal device 11 and has a notice address.

[0004] Next, packet transmission by Mobile IP will be described. First, when the mobile terminal device 11 moves to another domain, it acquires its own address in the destination domain as a notice address, and notifies the home agent 13 of the notice address via the external agent 201. The home agent 13 registers the noticed address from the mobile terminal device 11 in association with the home address of the mobile terminal device 11.

[0005] On the other hand, when transmitting the IP packet to the mobile terminal device 11, the remote terminal device 41 transmits the IP packet to the home address of the mobile terminal device 11. The IP packet reaches the home agent 13 via the IP network 202. The home agent 13 encapsulates the IP packet based on the registration information about the mobile terminal device 11, and then transfers the IP packet to the noticed address of the mobile terminal device 11. Upon receiving the encapsulated IP packet, the external agent 201 decapsulates and supplies the original IP packet to the mobile terminal device 11 having the awareness address.

[0006] When the mobile terminal device 11 exists in the home domain, the home agent 13 simply functions as a router, and an IP packet addressed to the mobile terminal device 11 is supplied to the mobile terminal device 11.

[0007] In this way, even if the mobile terminal device 11 moves across the domain, the IP packet addressed to the mobile terminal device 11 reaches the mobile terminal device 11 via the home agent 13 and the external agent 201. ..

[0008] However, when the IP packet addressed to the mobile terminal device 11 reaches the mobile terminal device 11 via the home agent 13, that is, in the case of triangular routing, there is a problem that the transmission delay becomes large. .. When executing data transmission that is sensitive to delay such as VoIP (Voice over IP), such transmission delay becomes a big problem.

Therefore, the IETF Internet Draft (draft-ietf-mobileip-optim-08.txt) proposes route optimization for solving the transmission delay problem due to the above-mentioned triangular routing. This route optimization uses a protocol that sets a shortcut path from the remote terminal device 41 to the noticed address of the mobile terminal device 11 without going through the home agent 13. FIG. 31 is a diagram illustrating route optimization with a conventional Mobile IP.

[0010] In this route optimization, the remote terminal device 41 periodically performs a join request message with the home agent 13 of the mobile terminal device 11 in order to acquire the current notice address of the mobile terminal device 11. Send and receive Bind Request Message and Bind Update Massage. The remote terminal device 41 acquires the current notice address of the mobile terminal device 11 based on the join update message obtained periodically, encapsulates the IP packet addressed to the mobile terminal device 11, and then moves to the notice address. Send.

Therefore, as shown in FIG. 31, the IP packet from the remote terminal device 41 to the mobile terminal device 11 arrives at the mobile terminal device 11 without passing through the home agent 13. This eliminates triangular routing.

[0012] Since the conventional route optimization method is configured as described above, the remote terminal device 41 periodically communicates with the home agent 13 of the mobile terminal device 11. It is necessary to send and receive messages, and there is a problem that it is difficult to suppress the power consumption of the terminal device 41 on the other side. When the remote terminal device 41 is a mobile terminal device, it is driven by the power of the battery, which is a particular problem.

[0013] Further, in the conventional route optimization method, since the IP header portion is doubled by encapsulating the IP packet, the home agent or the external agent of the domain to which the other party terminal device 41 belongs from the other party terminal device 41 to the other party terminal device 41. There is a problem that it is difficult to effectively use the transmission band to. VoIP packets are particularly problematic because the ratio of the header part to the data part is large.

[0014] The present invention has been made to solve the above-mentioned problems, and a combined update message from a home agent is received by a connected home agent or an external agent of the remote terminal device 41, and the home thereof is received. By allowing the agent or external agent to encapsulate and forward the packet addressed to the mobile terminal device 11, there is no need to periodically send and receive messages between the remote terminal device 41 and the home agent 13 of the mobile terminal device 11. , The power consumption of the other party terminal device 41 can be suppressed, and the amount of data transmitted from the other party terminal device 41 to the external agent of the domain to which the other party terminal device 41 belongs can be suppressed to effectively enable the transmission band. The purpose is to obtain a route optimization method and agent device that can be used.

[Means for Solving the Problems] The route optimization method according to the present invention is<u style="single">When the mobile terminal device moves to another network domain in a communication system that communicates between an external agent or mobile terminal device of the network domain to which the other party terminal device currently belongs and the other party terminal device, the other party terminal In the route optimization method for optimizing the communication path from the device to the mobile terminal device, an external agent or a home agent of the network domain to which the other party terminal device currently belongs sends a join update message from the home agent of the mobile terminal device. Upon receiving, the packet addressed to the mobile terminal device is forwarded to the current notice address of the mobile terminal device notified by the combined update message, and the external agent moves the remote terminal device to its own network domain. The communication system agent that acquires the information of the noticed address of the mobile terminal device from the external agent or home agent of the network domain of the destination network of the remote terminal device receives the join update message from the home agent of the mobile terminal device. Then, the packet addressed to the mobile terminal device was notified by the combined update message.</u><u style="single">Transferring to the current notice address of the mobile terminal device, when the external agent moves to its own network domain, the external agent or home agent of the network domain from which the other party terminal device is moved Get the information of the notice address of the mobile terminal device from</u>It is something like that.

[0016] The route optimization method according to the present invention is<u style="single">When the mobile terminal device moves to another network domain in a communication system that communicates between the mobile terminal device and the remote terminal device, the communication path from the remote terminal device to the mobile terminal device is optimized. In the route optimization method, the external agent or home agent of the network domain to which the other party terminal device currently belongs receives the join update message from the home agent of the mobile terminal device, and joins the packet addressed to the mobile terminal device. Transferred to the current notice address of the mobile terminal device notified by the update message, and when the external agent or home agent moves the remote terminal device to its own network domain, the destination of the remote terminal device is moved. Obtain information on the awareness address of the mobile terminal device from an external agent in the network domain of</u>It is something like that.

[0017] The route optimization method according to the present invention is<u style="single">When the mobile terminal device moves to another network domain in a communication system that communicates between the mobile terminal device and the remote terminal device, the communication path from the remote terminal device to the mobile terminal device is optimized. In the route optimization method, the external agent or home agent of the network domain to which the other party terminal device currently belongs receives the join update message from the home agent of the mobile terminal device, and joins the packet addressed to the mobile terminal device. Transfer to the current awareness address of the mobile terminal device notified in the update message, and the external agent or home agent of the network domain to which the other party terminal device currently belongs acquires the latest awareness address of the mobile terminal device. The join request message for is repeatedly transmitted to the home agent of the mobile terminal device, and the home agent of the mobile terminal device has a join response message having the latest notice address of the mobile terminal device in response to the join request message. Is transmitted to the external agent or home agent of the network domain to which the other party terminal device currently belongs, and the external agent or home agent of the network domain to which the other party terminal device currently belongs moves the other party terminal out of its own network domain. When the device moves, the update of the awareness address of the mobile terminal device is stopped.</u>It is something like that.

[0018] The route optimization method according to the present invention is<u style="single">Of the network domain to which the other terminal device currently belongs</u>The external agent or home agent stopped updating when certain conditions were met.<u style="single">Of mobile terminal devices</u>The update of the noticed address is restarted.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described.<u style="single">Reference example 1</u>Figure 1 shows the invention of the present invention.<u style="single">Reference example 1</u>It is a figure which shows an example of the network which applied the route optimization method by. In FIG. 1, 1 is an IP network (network domain) that is the home domain of the mobile terminal device 11, 2 is the Internet that connects IP networks 1 and 3 to 6 to each other, and 3 is the destination of the mobile terminal device 11. The IP network (network domain) that is the domain, 4 is the IP network (network domain) that is the home domain of the remote terminal device 41, and 5 is the IP network (network) that is the destination domain of the remote terminal device 41. Domain), and 6 is another IP network (network domain).

[0020] 11 is a mobile terminal device to which an IP address in the home domain (hereinafter referred to as a home address) is fixedly assigned, and 12 is a terminal device connected to the home agent 13 and existing in the IP network 1. It is a base station that communicates wirelessly between them, and 13 is a home agent (agent device) assigned to the home domain to which the mobile terminal device 11 belongs. In this case, the network address of IP network 1 is 10.76.51.0, the home address of mobile terminal device 11 is 10.76.51.100, and the IP address of home agent 13 is 10.76.51.254.

[0021] 31 is a base station connected to the external agent 32 and wirelessly communicates with the mobile terminal device 11 and the remote terminal device 41 existing in the IP network 3, and 32 is arranged in the IP network 3. It is an external agent (agent device). In this case, the network address of IP network 3 is 10.76.52.0 and the IP address of external agent 32 is 10.76.52.254.

Reference numeral 41 denotes a remote terminal device that is a communication partner of the mobile terminal device 11. The remote terminal device 41 may be either a fixed terminal device or a mobile terminal device. 42 is a base station that is connected to the home agent 43 and wirelessly communicates with a terminal device existing in the IP network 4, and 43 is a home agent (agent device) located in the home domain to which the other terminal device 41 belongs. ). In this case, the network address of IP network 4 is 10.76.55.0, the home address of the remote terminal device 41 is 10.76.55.100, and the IP address of the home agent 43 is 10.76.55.254.

51 is a base station connected to the external agent 52 and wirelessly communicates with a terminal device existing in the IP network 5, and 52 is an external agent (agent device) arranged in the IP network 5. .. In this case, the network address of IP network 5 is 10.76.53.0 and the IP address of external agent 52 is 10.76.53.254.

[0024] 61 is a base station connected to the external agent 62 and wirelessly communicates with the mobile terminal device 11 and the remote terminal device 41 existing in the IP network 6, and 62 is arranged in the IP network 6. An external agent with a noticed address. In this case, the network address of IP network 6 is 10.76.54.0 and the address of the external agent 62 is 10.76.54.254.

The home agent 13, the mobile terminal device 11, and the remote terminal device 41 each function as entities conforming to the Mobile IP specifications.

Next, the operation of each device and the agent will be described. First, the operation of the external agents 32, 52, 62 will be described. FIG. 2 is an SDL (Specification and Description Language) diagram explaining the operation of the external agents 32,52,62, and FIG. 3 is a connection terminal management table of the external agents 32,52,62 to which the mobile terminal device 11 is connected. FIG. 4 is a diagram showing an example of a join cache table held by external agents 32, 52, 62 to which the remote terminal device 41 is connected.

[0027] When the mobile terminal device 11 moves to the IP network 3,5,6, the registration request message addressed to the home agent 13 is sent to the external agent 32 of the IP network 3,5,6 via the base station 31,51,61. Send to, 52,62. The registration request message includes the home address of the mobile terminal device 11, the address of the home agent 13, the awareness address acquired by the IP networks 3, 5 and 6, and the valid time of this message.

[0028] When the external agent 32,52,62 receives the registration request message from the mobile terminal device 11 existing in the IP network 3,5,6 to which it belongs in step ST11 via the base station 31,51,61, the external agent 32,52,62 receives a registration request message. In step ST12, the connected terminal management table as shown in FIG. 3 is searched, and in step ST13, it is determined whether or not the mobile terminal device 11 is registered in the connected terminal management table, and the mobile terminal device 11 manages the connected terminal. If it is registered in the table, the registration information is updated based on the registration request message in step ST14, and if the mobile terminal device 11 is not registered in the connection terminal management table, the registration request message is displayed in step ST15. Based on this, the mobile terminal device 11 is registered in the connection terminal management table.

[0029] Then, in step ST16, the external agents 32, 52, 62 forward the registration request message to the home agent 13 of the mobile terminal device 11.

When the external agent 32,52,62 receives an IP packet from the terminal device in the Internet 2 or its own IP network 3,5,6 in step ST21, the external agent 32,52,62 examines the header part of the IP packet and examines the header part of the IP packet. Determines whether the destination of the IP packet is an IP address in its own IP network 3,5,6, and determines that the destination of the IP packet is an IP address in its own IP network 3,5,6. If it is determined, the IP packet is deencapsulated in step ST23, and the IP packet is supplied to the corresponding terminal device in the IP networks 3, 5 and 6 in step ST24.

On the other hand, if it is determined that the destination of the IP packet is not an IP address in its own IP network 3,5,6, in step ST25, the external agents 32,52,62 are as shown in FIG. The combined cache table (described later) is searched, and it is determined in step ST26 whether or not the mobile terminal device 11 which is the destination of the IP packet is registered in the combined cache table. If it is determined that the mobile terminal device 11 that is the destination of the IP packet is registered in the join cache table, the external agents 32,52,62 read the noticed address of the mobile terminal device 11 from the join cache table in step ST27. The IP packet is encapsulated, and the encapsulated IP packet is forwarded to the noticed address of the mobile terminal device 11 in step ST28. On the other hand, if it is determined that the mobile terminal device 11 which is the destination of the IP packet is not registered in the join cache table, the external agents 32,52,62 forward the IP packet as it is in step ST28 without encapsulation. ..

When the external agents 32, 52, 62 receive the join update message from the home agent 13 of the mobile terminal device 11 in step ST31, the external agents 32, 52, 62 search the join cache table as shown in FIG. 4 in step ST32. In step ST33, it is determined whether or not the mobile terminal device 11 notified by the join update message is registered in the join cache table, and the mobile terminal device 11 notified by the join update message is registered in the join cache table. If it is determined that the registration information is updated based on the join update message in step ST34, and if it is determined that the mobile terminal device 11 notified by the join update message is not registered in the join cache table, step ST35 In, the mobile terminal device 11 is registered in the join cache table based on the join update message. The join update message includes the home address, notice address, home agent address, valid time of this message, etc. of the mobile terminal device 11, and the same information is also included in each registration information of the join cache table. .. External agents 32,52,62 operate in this way.

Next, the operation of the remote terminal device 41 will be described. FIG. 5 is an SDL diagram illustrating the operation of the remote terminal device 41. The remote terminal device 41 receives the IP packet in step ST41 via the external agent 32,52,62 or the home agent 43. Because external agents 32,52,62 or home agents 43 perform IP packet encapsulation and decapsulation.<u style="single">Reference example 1</u>The remote terminal device 41 in the above does not have to perform the encapsulation and decapsulation of the IP packet.

Next, the operation of the mobile terminal device 11 will be described. FIG. 6 is an SDL diagram illustrating the operation of the mobile terminal device 11. In step ST51, the mobile terminal device 11 receives the registration response message from the home agent 13 in response to the registration request message. Further, in step ST61, the mobile terminal device 11 receives the agent advertisement from the external agents 32,52,62 of the IP network 3,5,6 in which it exists, and in step ST62, the notice address corresponding to the agent advertisement is set. Obtained, generate a registration request message including its own awareness address in step ST63, and send it to the home agent 13 via its external agents 32,52,62. Further, the mobile terminal device 11 receives the IP packet in step ST71 via the external agents 32, 52, 62 or the home agent 13.

[0035] FIG. 7 is an SDL diagram illustrating the operation of the home agent 13, and FIG. 8 is a diagram showing an example of an awareness address management table possessed by the home agent 13 for the mobile terminal device 11. When the home agent 13 of the mobile terminal device 11 receives the registration request message from the mobile terminal device 11 in step ST81, the home agent 13 searches the awareness address management table as shown in FIG. 8 in step ST82, and the mobile terminal device in step ST83. It is determined whether or not 11 is registered in the noticed address management table, and if the mobile terminal device 11 is registered in the noticed address management table, the registration information is updated based on the registration request message in step ST84. If the mobile terminal device 11 is not registered in the awareness address management table, the mobile terminal device 11 is registered in the awareness address management table in step ST85 based on the registration request message.

[0036] Then, in step ST86, the home agent 13 transmits a registration response message indicating that the registration process is completed to the mobile terminal device 11.

When the home agent 13 receives an IP packet from the Internet 2 or a terminal device in its own IP network 3,5,6 in step ST91, the home agent 13 searches the noticed address management table in step ST92, and in step ST93. It is determined whether or not the mobile terminal device 11 which is the destination of the IP packet is registered in the noticed address management table.

[0038] When it is determined that the mobile terminal device 11 which is the destination of the IP packet is registered in the noticed address management table, the home agent 13 uses the noticed address management table to find the noticed address of the mobile terminal device 11 in step ST94. And encapsulate the IP packet. Then, in step ST95, the home agent 13 sends a combined update message about the mobile terminal device 11 which is the destination of the IP packet to the source of the IP packet, and in step ST96, the encapsulated IP packet is transmitted. Transfer to the destination mobile terminal device 11. On the other hand, when it is determined that the mobile terminal device 11 which is the destination of the IP packet is not registered in the noticed address management table, the home agent 13 determines that the mobile terminal device 11 exists in the home domain and bases in step ST96. The IP packet is supplied to the mobile terminal device 11 via the station 12.

[0039] Further, when the home agent 13 receives the join request message for the mobile terminal device 11 from the external agents 32, 52, 62 of the domain to which the remote terminal device 11 currently belongs in step ST101, FIG. 8 in step ST102. The noticed address management table as shown in (1) is searched, and in step ST103, a join update message for the mobile terminal device 11 is sent to the external agents 32, 52, 62.

[0040] The home agent 13 operates in this way. The home agent 43 may also operate with respect to the remote terminal device 41 in the same manner. As described above, each device and agent operates.

Next, as shown in FIG. 1, for example, when the mobile terminal device 11 moves from the IP network 1 to the IP network 3, the noticed address of the mobile terminal device 11 is registered in the home agent 13 and the other party. The packet transmission to the mobile terminal device 11 by the terminal device 41 will be described. FIG. 9 is a diagram showing a sequence of registration of a noticed address and packet transmission of the mobile terminal device 11. Since the base stations 12, 31, 42, 51, 61 always only execute transparent transfer, the description of their operation will be omitted. In this case, since the other party terminal device 41 does not move, it may be treated as a fixed terminal.

First, when the mobile terminal device 11 moves from the IP network 1 to the IP network 3, the registration of the noticed address of the mobile terminal device 11 in the home agent 13 will be described.

[0043] When the mobile terminal device 11 moves from the IP network 1 to the IP network 3, the mobile terminal device 11 acquires a notice address by DHCP (Dynamic Host Configuration Protocol) or the like. The mobile terminal device 11 sends a registration request message in order to register the acquired awareness address with the external agent 32 and the home agent 13. This registration request message has a notice address of the mobile terminal device 11, a home address of the mobile terminal device 11, an address of the home agent 13 of the mobile terminal device 11, and the like.

[0044] Upon receiving the registration request message, the external agent 32 determines that the new mobile terminal device has entered its own IP network 3, and determines that the mobile terminal device 11 has entered the home address 10.76.51.100 and the home agent 13 address 10.76.51.254. And are registered in the connection terminal management table as shown in Fig. 3.

[0045] Further, the external agent 32 forwards the registration request message to the home agent 13 in order to register the new notice address of the mobile terminal device 11 with the home agent 13 of the mobile terminal device 11.

When the home agent 13 receives the registration request message, as shown in FIG. 8, the home address of the mobile terminal device 11 in the notice address management table is the new notice address included in the registration request message 10.76. Updated the correspondence between 51.100 and the awareness address 10.76.52.254.

Before the mobile terminal device 11 moved to the IP network 3, the mobile terminal device 11 did not have a notice address because it existed in the IP network 1 which is the home domain, and moved to the notice address management table. The correspondence between the home address of the terminal device 11 and the noticed address was not registered. Therefore, when the mobile terminal device 11 moves to the IP network 3, the first awareness address 10.76.52.254 is supplied to the home agent 13. Then, the home agent 13 newly registers the notice address of the mobile terminal device 11 in the notice address management table as shown in FIG. Then, when the registration or update of the notice address is completed, the home agent 13 sends a registration response message to the sender of the registration request message in order to notify the fact.

[0048] When the external agent 32 receives the registration response message, the external agent 32 transfers the registration response message to the mobile terminal device 11 in order to notify that the registration process is completed, and the mobile terminal device 11 transfers the registration response message. To receive.

With the above, the registration process of the mobile terminal device 11 to the home agent 13 is completed. At this point, registration information about the mobile terminal device 11 is recorded in the connection terminal management table of the external agent 32 and the noticed address management table of the home agent 13, respectively, as shown in FIGS. 3 and 8, respectively. The above-mentioned registration process is a registration process according to the specifications of Mobile IP.

Next, route control from the remote terminal device 41 to the mobile terminal device 11 will be described. When the remote terminal device 41 transmits an IP packet to the mobile terminal device 11, it outputs the IP packet without encapsulation. This IP packet is received by the external agent 52 of the IP network 5 to which the remote terminal device 41 currently belongs. If the destination of the IP packet (home address 10.76.51.100 of the mobile terminal device 11) does not exist in the join cache table shown in FIG. 4, the external agent 52 transparently transfers the IP packet to the destination as it is.

When the home agent 13 receives the IP packet, the home agent 13 encapsulates the IP packet based on the registration information of the mobile terminal device 11 in the awareness address management table generated by the above-mentioned registration process, and the mobile terminal device 11 Tunnel transfer to the awareness address 10.76.52.254.

The IP packet tunnel-forwarded by the home agent 13 reaches the external agent 32, is decapsulated by the external agent 32, and finally the original IP packet reaches the mobile terminal device 11.

[0053] Up to this point, since there is no registration information about the mobile terminal device 11 in the join cache table of the external agent 52, the packet route is triangular routing.

[0054] When the home agent 13 tunnels an IP packet, it transmits a combined update message to the remote terminal device 41, which is the source of the IP packet. The external agent 52 receives the join update message and records the registration information of the mobile terminal device 11 in the join cache table as shown in FIG. Since the remote terminal device 41 is not supplied with the combined update message, the other party terminal device 41 transmits the packet to the home address 10.76.51.100 of the mobile terminal device 11 without encapsulation, as in the case of the packet transmission described above.

After the registration information about the mobile terminal device 11 is recorded in the join cache table of the external agent 52, the external agent 52 uses the remote agent 52 based on the registration information of the mobile terminal device 11 in the join cache table. The IP packet from the device 41 is encapsulated and tunneled to the awareness address 10.76.52.254 of the mobile terminal device 11. At this time, the external agent 52 reads the destination IP address 10.76.51.100 from the header part of the IP packet from the remote terminal device 41, searches for the registration information having the same home address as the destination IP address, and searches for the registration information. Let 10.76.52.254 be the awareness address of the mobile terminal device 11.

[0056] Therefore, the encapsulated IP packet reaches the external agent 32 without going through the home agent 13. This eliminates triangular routing.

[0057] As described above, this<u style="single">Reference example 1</u>According to the report, the combined update message from the home agent 13 is received by the connected external agent 32,52,62 of the remote terminal device 41, and the external agent 32,52,62 receives the IP addressed to the mobile terminal device 11. Since the packet is encapsulated and transferred, the need for regular communication between the remote terminal device 41 and the home agent 13 of the mobile terminal device 11 is eliminated, and the power consumption of the remote terminal device 41 is suppressed. At the same time, it is possible to obtain the effect that the transmission band can be effectively used by suppressing the amount of data transmitted from the remote terminal device 41 to the external agent 52 of the domain to which the remote terminal device 41 belongs.

【0058】<u style="single">Reference example 2</u>. Of this invention<u style="single">Reference example 2</u>The external agents 32, 52, 62 in the above send a join request message prompting the transmission of the join update message to the home agent 13 before the valid time set in the information of the join update message elapses. This join request message conforms to the Internet draft (draft-ietf-mobileip-optim-08.txt) and includes the home address of the mobile terminal device 11.

[ 0059] The home agent 13 that has received the binding request message sends back the latest care-of address information corresponding to the home address of the mobile terminal device 11 to the source of the binding request message. Upon receiving this join update message, the external agents 32, 52, 62 update the notice address of the mobile terminal device 11 in the join cache table based on the join update message.

[0060] For other items<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0061] As described above, this<u style="single">Reference example 2</u>According to the report, external agents 32,52,62 of the domain to which the remote terminal device 41 belongs should periodically send and receive messages to and from the home agent 13 in order to obtain the latest notice address of the mobile terminal device 11. Therefore, the route can be optimized without performing regular communication between the other side terminal device 41 and the home agent 13, the packet can be forwarded to the latest notice address by tunnel, and the other side can be forwarded. The effect that the amount of data transmitted from the terminal device 41 to the external agents 32, 52, 62 of the domain to which the other party terminal device 41 belongs can be further suppressed can be obtained.

【0062】<u style="single">Reference example 3</u>Figure 10 shows the invention of the present invention.<u style="single">Reference example 3</u>It is a figure which shows an example of the network which applied the route optimization method by. In FIG. 10, 11-1 and 11-2 are mobile terminal devices whose home domain is IP network 1, and 41-1 and 41-2 are communication partners of mobile terminal devices 11-1 and 11-2. , The other party's terminal device whose home domain is IP network 4. The home address of the remote terminal device 41-1 is 10.76.55.100, and the home address of the mobile terminal device 11-1, which is the communication partner of the remote terminal device 41-1, is 10.76.51.100. The home address of the remote terminal device 41-2 is 10.76.55.101, and the home address of the mobile terminal device 11-2, which is the communication partner of the remote terminal device 41-2, is 10.765.51.101.

[0063] Of the present invention<u style="single">Reference example 3</u>As shown in FIG. 10, the external agents 32, 52, 62 in the above are a plurality of mobile terminal devices that are communication partners of the other party terminal devices 41-1, 41-2 existing in their own IP networks 3, 5, 6. If the home domains of 11-1, 11-2 are the same, the join request messages for those mobile terminal devices 11-1, 11-2 are combined into one extended join request message, and the extended join request is combined. It is intended to send a message.

[0064] In addition,<u style="single">Reference example 3</u>The external agents 32,52,62 in the above have an HA support table that records the home agents that can interpret the extended join request message, and refer to the HA support table to the destination of the extended join request message. Send the extended join request message only if it is a home agent that can interpret the extended join request message, otherwise send a normal (non-extended) join request message.

[0065] Fig. 11 shows<u style="single">Reference example 3</u>It is a figure which shows an example of the extended join request message in. As shown in FIG. 11, in addition to the information contained in a normal join request message, the extended join request message includes, for example, an extension type 101 fixed to "38", an extension length 102, and a vendor-specific identifier. Includes the vendor identifier 103, the vendor extension type 104 that describes the extension type for each vendor, and the home addresses 105, 106 of the mobile terminal device that requests the join update message.

Note that this message extension conforms to the IETF's Internet Draft (draft-ietf-vender-ext-05.txt) Critical Vendor Extension Format. According to this draft, if an external agent that cannot interpret the extension receives the extended message in the Critical vendor extended format, the entire message is ignored. Therefore, when a home agent that cannot interpret this extension receives this extended join request message, it does not take any action on the message.

[0067] FIG. 12 is a diagram showing an example of an HA support table. As shown in FIG. 12, the IP address of the home agent 13 of the mobile terminal device 11 and the information (YES or NO) as to whether or not the extended join request message can be interpreted are described in association with each other.

[0068] Next, the operation will be described. Of this invention<u style="single">Reference example 3</u>The external agents 32,52,62 in the above are a plurality of mobile terminal devices 11-1, 11-2 that are communication partners of the other party terminal devices 41-1, 41-2 existing in their own IP networks 3, 5, 6. If the home domains of are the same, refer to the HA support table and send the extended join request message described above only to the interpretable home agent 13, and to the other home agents 13 as usual (not extended). ) Send a join request message.

Next, the operation of the home agent 13 capable of interpreting the above-mentioned extended join request message will be described. FIG. 13 is an SDL diagram illustrating the operation when a home agent capable of interpreting the extended join request message receives the join request message. The home agent 13<u style="single">Reference example 1</u>In steps ST101 to ST103, the latest notice address corresponding to the home address of one mobile terminal device 11 included in the normal part of the received join request message is read from the notice address management table in the same manner as the home agent 13 in the above. Send a join update message containing the latest notice address to the external agents 32,52,62 from which the join request message was sent.

Next, in step ST111, the home agent 13 determines whether or not the received join request message has an extended portion, and if it determines that there is no extended portion, terminates the process and terminates the extended portion. If it is determined that there is, the latest notice address is read from the notice address management table in step ST112 for the home address of the remaining mobile terminal device 11 in the extension part, and the join including the latest notice address is included in step ST113. Send the update message to the source of the join request message. Then, the home agent 13 repeats the processes of steps ST111 to ST113 until the home address of the mobile terminal device in the extended portion disappears.

[0071] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0072] As described above, this<u style="single">Reference example 3</u>According to, if the home domains of multiple mobile terminal devices 11-1, 11-2, which are the transmission destinations of the other party terminal devices 41-1, 41-2, are the same, the external agents 32, 52, 62 will use them. Since the join request messages for the mobile terminal devices 11-1 and 11-2 of the above are combined into one extended join request message and the extended join request message is sent, the external agents 32,52,62 Since the amount of data transmitted to the home agent 13 is reduced, the effect of reducing the switching load by the router and reducing the load on the network can be obtained.

【0073】<u style="single">Reference example 4</u>. Of this invention<u style="single">Reference example 4</u>External agents 32,52,62 in the above should introduce a subnet mask to the HA support table and collectively set whether or not the extended join request message can be interpreted for the home agent 13 included in that subnet. It is the one that was made.

[0074] FIG. 14 is a diagram showing an example of an HA support table in which a subnet mask is introduced. The HA support table shown in Figure 14 shows that the home agent 13 of the IP network belonging to net address 10.76.0.0, except for IP address 10.76.51.254, can interpret the extended join request message described above. ..

[0075] For other operations, etc.<u style="single">Reference example 3</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0076] As described above, this<u style="single">Reference example 4</u>According to the HA support table, the subnet mask can be used to collectively set whether or not the extended join request message can be interpreted for all home agents 13 in the subnet. The effect is that you can easily create.

【0077】<u style="single">Reference example 5</u>. Of this invention<u style="single">Reference example 5</u>External agents 32,52,62 in respond to notifications from home agent 13<u style="single">Reference example 3</u>The HA support table in is set dynamically.

[0078] The home agent 13 of the mobile terminal device 11 can interpret the above-mentioned extended join request message, and the external agents 32,52,62 of the IP network 3,5,6 to which the remote terminal device 41 currently belongs. In order to notify to, the join update message sent at a time other than the response of the join request message is sent with an extension part for notifying that fact added.

FIG. 15 is a diagram showing an example of a join update message when the HA support table is dynamically set. As shown in FIG. 15, in addition to the information contained in the normal join request message, the join update message in this case includes, for example, an extension type 111 fixed to "134", an extension length 112, and vendor-specific. It includes a vendor identifier 113, which is an identifier, and a vendor extension type 114, which describes the extension type for each vendor.

[0080] When the external agents 32, 52, 62 receive the extended join update message, they rewrite the registration information in the HA support table for the home agent 13 that is the source of the extended join update message.

[0081] The extension of this message conforms to the normal vendor extension format of the IETF Internet Draft (draft-ietf-vender-ext-05.txt). According to this draft, if an external agent that cannot interpret the extension receives a message that is normally extended in the vendor extension format, the extension must be ignored and the message processed. That is, if an external agent that cannot interpret this extension receives a join update message with this extension, only the extension is ignored and the rest are processed normally.

[0082] For other items,<u style="single">Reference example 1</u>Since it is the same as the above, the description thereof will be omitted.

[0083] As described above, this<u style="single">Reference example 5</u>According to the report, the external agents 32,52,62 dynamically set the HA support table in response to the notification from the home agent 13, so that the network administrator can support the HA of each external agent 32,52,62. Whether or not the home agent 13 can interpret the extended join request message can be automatically set in the HA support table without setting the table one by one, and the setting work of the HA support table can be simplified. The effect is obtained.

【0084】<u style="single">Reference example 6</u>. Of this invention<u style="single">Reference example 6</u>External agents 32,52,62 in the above are intended to approve only join update messages from the limited home agent 13.

[0085] In route optimization, if the noticed address by the join update message is maliciously changed, the packet does not reach the correct destination, but reaches another wrong destination. Therefore, from the viewpoint of security, it is desirable to use only the join update message from only the trusted home agent 13. Therefore,<u style="single">Reference example 6</u>External agents 32,52,62 in, approve only join update messages from the limited home agent 13.

[0086] Of the present invention<u style="single">Reference example 6</u>External agents 32,52,62 in have an internal table that records their limited home agents 13. The external agents 32,52,62 update the notice address of the mobile terminal device 11 based only on the join update message from the home agent 13 registered in the internal table, and ignore the join update messages from the other home agents 13. To do.

[0087] FIG. 16 is a diagram showing an example of an internal table in which the limited home agents 13 are recorded. As shown in FIG. 16, in this internal table, the availability of the join update message is recorded in association with the IP address of each home agent 13. In the case of the internal table shown in Figure 16, join update messages from home agent 13 with IP addresses 10.76.51.254,10.76.55.254 are accepted, but join update messages from other home agents 13 are not.

[0088] For other operations, etc.<u style="single">Reference example 3</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0089] As described above, this<u style="single">Reference example 6</u>According to this, only the join update message from the limited home agent 13 is approved, so only the join update message from the trusted home agent 13 can be used, and security can be ensured. The effect is obtained.

【0090】<u style="single">Reference example 7</u>. Of this invention<u style="single">Reference example 7</u>External agents 32,52,62 in<u style="single">Reference example 6</u>The home agents 13 registered in the internal table in the above can be grouped by the subnet mask.

[0091] FIG. 17 is a diagram showing an example of an internal table in which grouping by subnet mask is introduced. In the case of the internal table shown in Figure 17, only join update messages from home agents 13 belonging to the subnet with IP address 10.76.0.0, other than home agent 13 with IP address 10.76.55.254, are approved.

[0092] As described above, this<u style="single">Reference example 7</u>According to this, when limiting the home agents 13 that are approved for join update messages, the home agents are grouped by subnet mask, so it is easy to set the limit for home agents 13 that are approved for join update messages. The effect of being able to do is obtained.

【0093】<u style="single">Reference example 8</u>. this<u style="single">Reference example 8</u>The external agents 32, 52, 62 in the above are intended to encapsulate only IP packets from a specific remote terminal device 41-1,41-2 and transfer them through a tunnel.

[0094] This<u style="single">Reference example 8</u>The external agents 32,52,62 in the above indicate whether or not to execute route optimization for each remote terminal device 41-i (i = 1,2) existing in its own IP network 3,5,6. It has a service setting table in which information is described.

[0095] FIG. 18 is a diagram showing an example of a service setting table. In the network shown in FIG. 10, when the service setting table shown in FIG. 18 is set, the external agents 32,52,62 encapsulate the IP packet from the remote terminal device 41-1 at the home address 10.76.55.100. And tunnel transfer, and transparently transfer the IP packet from the other terminal device 41-2 with the home address 10.76.55.101 as it is.

Next, the operation will be described. Figure 19 received an IP packet<u style="single">Reference example 8</u>It is an SDL diagram explaining the operation of the external agents 32, 52, 62 in. In the network shown in Figure 10, this<u style="single">Reference example 8</u>When the external agent 32,52,62 in the above receives an IP packet from the terminal device in the Internet 2 or its own IP network 3,5,6 in step ST21, it examines the header part of the IP packet and examines the header part of the IP packet. When it is determined whether or not the destination is an IP address in its own IP network 3,5,6, and it is determined that the destination of the IP packet is an IP address in its own IP network 3,5,6. Deencapsulates the IP packet in step ST23 and supplies the IP packet to the corresponding terminal device in the IP network 3,5,6 in step ST24.

On the other hand, if it is determined that the destination of the IP packet is not an IP address in its own IP network 3,5,6, the external agents 32,52,62 refer to the service setting table in step ST121. , It is determined in step ST122 whether or not the route is optimized for the packet.

[0098] When it is determined in the service setting table that the route is optimized for the packet, the external agents 32,52,62 put the mobile terminal device 11 which is the destination of the IP packet in the join cache table in step ST123. Determine if it is registered. If the mobile terminal device 11 that is the destination of the IP packet is determined to be registered in the join cache table, the external agents 32,52,62 encapsulate the IP packet in step ST125 and after encapsulation in step ST126. The IP packet is forwarded to the noticed address of the mobile terminal device 11.

[0099] On the other hand, when it is determined in the service setting table that the route is not optimized for the packet, or when it is determined that the mobile terminal device 11 which is the destination of the IP packet is not registered in the join cache table, it is external. Agents 32,52,62 forward the IP packet as is in step ST126 without encapsulation.

[0100] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0101] As described above, this<u style="single">Reference example 8</u>According to the report, the external agents 32, 52, 62 encapsulate only the IP packet from the specific remote terminal device 41-i and forward it through the tunnel, so whether or not the network administrator executes the route optimization. Can be set individually. For example, route optimization is not performed for data that is resistant to delay (data communication that does not require real-time performance), and route optimization is performed only for data that is sensitive to delay (data such as VoIP). The effect of being able to execute the conversion and reducing the load on the external agents 32,52,62 can be obtained.

【0102】<u style="single">Reference example 9</u>. Of this invention<u style="single">Reference example 9</u>The external agents 32, 52, 62 in the above introduce a subnet mask in the service setting table, and collectively set whether or not to execute route optimization for all the remote terminal devices 41-i belonging to the subnet. It was made like this.

[0103] FIG. 20 is a diagram showing an example of a service setting table in which a subnet mask is introduced. The service setting table shown in FIG. 20 shows that route optimization is performed only for IP packets from the remote terminal device belonging to the subnet 10.76.55.0, excluding the IP address 10.76.55.101.

[0104] For other operations, etc.<u style="single">Reference example 8</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0105] As described above, this<u style="single">Reference example 9</u>According to the service setting table, it is possible to collectively set whether or not to execute route optimization for all the remote terminal devices 41-i in the subnet using the subnet mask. The effect is that you can easily create.

【0106】<u style="single">Reference example 10</u>. Of this invention<u style="single">Reference example 10</u>The external agents 32, 52, 62 in the above are designed to adjust the transmission interval of the join request message according to the frequency of changing the notice address of the mobile terminal device 11.

[0107] Next, the operation will be described. FIG. 21 is an SDL diagram illustrating the operation of the external agents 32, 52, 62 adjusting the transmission interval of the join request message. Figure 22 shows this<u style="single">Reference example 10</u>It is a figure which shows the join cache table of the external agent 32,52,62 in.

[0108] When the external agents 32, 52, 62 receive the join update message in step ST141, the external agent 32,52,62 searches the join cache table for the mobile terminal device 11 corresponding to the join update message in step ST142.

[0109] Then, in step ST143, the external agents 32, 52, 62 have the mobile terminal device 11 registered in the join cache table, and the notice address included in the join update message is the notice address in the join cache table. It is determined that they are the same, and it is determined that the mobile terminal device 11 is not registered in the join cache table, or that the notice address included in the join update message is not the same as the notice address in the join cache table. In this case, the number of changes in the notice address is counted in step ST144, and the notice address in the join cache table is updated with the care address included in the join update message in step ST145. If the mobile terminal device 11 is not registered in the join cache table, the number of times the notice address is changed is set to 0, and the mobile terminal device 11 is registered in the join cache table.

[0110] As shown in FIG. 22, the number of changes and the update priority of the above-mentioned awareness address are recorded in the join cache table for each mobile terminal device 11.

[0111] Then, in step ST146, the external agents 32, 52, 62 calculate the update priority according to the number of changes of the notice address.

[0112] On the other hand, if the mobile terminal device 11 is registered in the join cache table and it is determined that the notice address included in the join update message is the same as the notice address in the join cache table, the notice address is set. There is no need to change it, so the process ends.

Further, when a timeout occurs in the built-in timer that notifies the trigger for transmitting the join request message in step ST131, the external agents 32,52,62 notice in step ST132 the mobile terminal device 11 corresponding to the timer. Look up the address in the join cache table. Then, the external agent sends a join request message in step ST133, resets the number of changes in the notice address to 0 in step ST134, and calculates the timer value according to the update priority. Then, the external agents 32, 52, 62 activate a timer in step ST135 to obtain the timing to send the next join request message.

[0114] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0115] As described above, this<u style="single">Reference example 10</u>According to the report, the external agent 32,52,62 adjusts the transmission interval of the join request message according to the change frequency of the notice address, so the join between the external agent 32,52,62 and the home agent 13 The effect is that request messages and combined update messages are sent and received at an appropriate frequency, unnecessary messages are sent and received, and network traffic can be reduced.

【0116】<u style="single">Reference example 11</u>. Of this invention<u style="single">Reference example 11</u>External agents 32,52,62 in<u style="single">Reference example 10</u>The initial value of the update priority in is set for each mobile terminal device 11-i.

[0117] Fig. 23 shows this<u style="single">Reference example 11</u>It is a figure which shows an example of the service setting table which the external agents 32, 52, 62 have in. In the service setting table shown in FIG. 23, the initial value of the update priority of the mobile terminal device 11-1 is set to 5, and the initial value of the update priority of the mobile terminal device 11-2 is set to 3. Note that this initial value is preset by the network administrator.

[0118] Next, the operation will be described. The external agents 32,52,62 of the IP network 3,5,6 to which the remote terminal device 41 currently belongs reads the initial value of the update priority for each mobile terminal device 11-i from the service setting table, and updates the initial value. A timer value is calculated according to the initial value of the priority, and a timer is activated for each mobile terminal device 11-i to obtain the timing for transmitting the next join request message.

[0119] For other operations,<u style="single">Reference example 10</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0120] For example, when the initial value of the update priority is set as shown in FIG. 23, if the valid times of the combined update messages are the same, the mobile terminal device is transmitted from the combined request message for the mobile terminal device 11-1. Join request messages about 11-2 are sent frequently.

[0121] As described above, this<u style="single">Reference example 11</u>According to the report, the initial value of the update priority is set for each mobile terminal device 11-i in the external agents 32, 52, 62, so that the route optimization service can be provided with different quality for each mobile terminal device 11-i. The effect of being able to provide is obtained.

【0122】<u style="single">Reference example 12</u>. Of this invention<u style="single">Reference example 12</u>The external agents 32, 52, 62 in the above register a cache table that joins a plurality of notice addresses to one mobile terminal device 11 as necessary, and a plurality of IP packets addressed to the home address of the mobile terminal device 11. It is designed to be tunneled to each of the noticed addresses of.

[0123] When the mobile terminal device 11 is on the boundary of a plurality of IP networks, handover may occur frequently. In that case, the mobile terminal device 11 frequently notifies the home agent 13 of the change of the notice address, which not only increases the network load but also increases the power consumption of the mobile terminal device 11. Therefore, in MobileIP, one mobile terminal device 11 registers a plurality of notice addresses in the home agent 13 so that the mobile terminal device 11 located at the boundary of a plurality of IP networks does not have to change the notice address frequently. Allows you to. Then, the home agent 13 in which the plurality of awareness addresses are registered transfers the IP packet addressed to the mobile terminal device 11 to each of the plurality of registered awareness addresses. In the case of triangular routing, the IP packet is forwarded to a plurality of notice addresses in this way, but in the conventional route optimization, the IP packet addressed to the mobile terminal device does not pass through the home agent, so the multiple notice addresses IP packets are forwarded to only one of them.

Therefore, the present invention<u style="single">Reference example 12</u>The external agents 32, 52, 62 in the above register a plurality of awareness addresses registered in the home agent 13 in the join cache table and optimize the route to those awareness addresses.

[0125] Next, the operation will be described. Figure 24 shows<u style="single">Reference example 12</u>It is a figure which shows an example of the extended join update message in. When the home agent 13 in which a plurality of notice addresses are registered for one mobile terminal device 11 receives the join request message for the mobile terminal device 11, the extended join update message shown in FIG. 24 is sent to the join request message. Sends to external agents 32,52,62, which is the source of. In the extended part of the join update message, the second and subsequent notice addresses are described.

Upon receiving this extended join update message, the external agents 32,52,62 read one notice address from the normal part, read the remaining notice addresses from the extended part, and correspond to the mobile terminal device 11. Then, register those notice addresses in the join cache table.

When the external agents 32, 52, 62 receive the IP packet addressed to the home address of the mobile terminal device 11, the external agent 32, 52, 62 tunnels the IP packet to each of the plurality of notice addresses corresponding to the home address. To do.

[0128] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0129] As described above, this<u style="single">Reference example 12</u>According to the external agents 32,52,62, if necessary, a combination cache table of a plurality of notice addresses is registered for one mobile terminal device 11, and an IP packet addressed to the home address of the mobile terminal device 11 is sent. Since tunnel transfer is performed to each of these plurality of awareness addresses, even if the awareness address of the mobile terminal device 11 located at the boundary of the network domain changes frequently, the awareness address registration process is performed every time the awareness address is changed. The effect that the IP packet can be reliably transmitted to the mobile terminal device 11 can be obtained without doing so.

【0130】<u style="single">Embodiment 1</u>. Of this invention<u style="single">Embodiment 1</u>The external agent 32,52,62 in is from the external agent 32,52,62 of the original IP network 3,5,6 when the remote terminal device 41 moves to its own IP network 3,5,6. The registration information of the join cache table is acquired and recorded in its own join cache table.

[0131] In the conventional route optimization method, when the remote terminal device that is the source of the IP packet moves to another IP network, the external agent of the destination network joins the remote terminal device. Since the cache table does not have the registration information, the IP packet from the remote terminal device temporarily passes through the home agent of the destination mobile terminal device until the join update message is received. That is, the operation when the other party terminal device first transmits an IP packet in the sequence shown in FIG. 9 is executed every time the other party terminal device moves to another IP network, and temporarily becomes triangular routing.

[0132] Therefore, this<u style="single">Embodiment 1</u>When the other party terminal device 41 moves to its own IP network in order to eliminate the temporary triangular routing when the other party terminal device 41 moves to another IP network, the external agents 32, 52, 62 in To get the registration information of the join cache table from the external agents 32,52,62 of the original IP network.

[0133] Next, the operation will be described. FIG. 25 is a diagram showing a network when the remote terminal device 41 moves to another IP network 6 in the network shown in FIG. 26 and 27 are<u style="single">Embodiment 1</u>It is an SDL diagram explaining the operation of the external agents 32, 52, 62 in.

[0134] When the external agents 32, 52, 62 receive the registration request message in step ST11, the extension portion (extended to the registration request message in step ST151) after the processing of step ST12, step ST13, and step ST14 or step ST15 is completed. It is determined whether or not there is (described later), and if it is determined that the registration request message has an extended part, in step ST152, the external agents 32, 52, 62 are notified of the noticed address of the other terminal device 41. The combined update message for this is sent to the external agents 32,52,62 of the IP network where the other terminal device 41 previously existed. Then, in step ST16, the external agents 32, 52, 62 transfer the registration request message to the home agent 13 of the source mobile terminal device 11 or the home agent 43 of the remote terminal device 41.

[0135] When the external agent 32,52,62 receives the IP packet in step ST21, it determines in step ST22 that the destination of the IP packet is an IP address in its own IP network 3,5,6. If so, decapsulate the IP packet in step ST23.

[0136] Then, in step ST161, the external agents 32,52,62 search the connection management table for the terminal device whose IP packet destination address matches the home address, and in step ST162, the destination address of the IP packet is the home address. If it is determined whether or not there is a terminal device that matches the home address and it is determined that there is a terminal device whose destination address of the IP packet matches the home address, the IP of the external agent 32,52,62 Since the destination terminal device exists in networks 3, 5 and 6, the IP packet is supplied to the terminal device in step ST24.

[0137] On the other hand, if it is determined that the terminal device whose destination address of the IP packet matches the home address does not exist in the connection terminal management table, the destination is sent to the IP networks 3,5,6 of the external agent 32,52,62. Since the terminal device does not exist, the external agents 32, 52, 62 search the join cache table in step ST163, and whether or not the mobile terminal device 11 which is the destination of the IP packet is registered in the join cache table in step ST164. To judge. If it is determined that the mobile terminal device 11 that is the destination of the IP packet is registered in the join cache table, the external agents 32,52,62 encapsulate the IP packet in step ST165, and after encapsulation in step ST166. Forward the IP packet to the current awareness address of the mobile terminal device 11. At this time, in step ST167, a warning is given that the destination mobile terminal device 11 is not connected to the IP networks 3,5,6 of the external agents 32,52,62. On the other hand, if it is determined that the mobile terminal device 11 which is the destination of the IP packet is not registered in the join cache table, the external agents 32,52,62 discard the IP packet.

[0138] Further, when the external agents 32, 52, 62 receive the join update message in step ST31, the join update message is sent in step ST171 after the processing of step ST32, step ST33, and step ST34 or step ST35. If it is determined whether or not the join update message is from another external agent 32,52,62, and if it is determined that the join update message is from another external agent 32,52,62, the self is determined in step ST172. A join response message that describes the contents of the join cache table of is sent to the external agents 32,52,62 that are the sources of the join update message.

[0139] When the external agents 32, 52, 62 receive the join response message in step ST181, in step ST182, the join cache table is generated based on the contents of the join response message, or the registration information is stored in the join cache. Add to table.

Next, the operation of each device and the agent when the remote terminal device 41 moves from the IP network 5 to the IP network 6 will be described. FIG. 28 is a diagram showing a sequence of operations of each device and agent when the remote terminal device 41 moves to another IP network 6. Since the base stations 12, 31, 42, 51, 61 always only execute transparent transfer, the description of their operation will be omitted.

As shown in FIG. 25, when the remote terminal device 41 moves from the IP network 5 to the IP network 6, it acquires a notice address by an agent advertisement or the like by an external agent 62.

[0142] The remote terminal device 41 that has acquired the new awareness address sends a registration request message to the external agent 62 of the IP network 6 to which it currently belongs in order to notify and register it to its own home agent 43.

[0143] This registration request message is extended and includes an instruction for notifying the external agent 52 of the original IP network 5 of the noticed address of the remote terminal device 41. This extension complies with the IETF Internet Draft (draft-ietf-mobileip-optim-08.txt), and this registration request message contains the original notice address of the other terminal device 41 and the new care address. It has been.

[0144] When the external agent 62 receives the registration request message, it generates and sends a combined update message for notifying the external agent 52 of the noticed address of the other party terminal device 41.

[0145] When the external agent 52 receives the join update message, the external agent 52 associates the original notice address of the remote terminal device 41 with the new notice address to generate a join cache table, and externally sends the join response message. Send to agent 62. After that, when the external agent 52 receives the IP packet addressed to the original noticed address of the remote terminal device 41, the external agent 52 tunnels the IP packet to the new noticed address.

[0146] The join response message sent by the external agent 52 is extended to notify the external agent 62 of the registration information of the join cache table in the external agent 52. Figure 29 shows<u style="single">Embodiment 1</u>It is a figure which shows an example of the combined response message extended in. As shown in FIG. 29, the extended portion of the join response message includes the home address of the mobile terminal device 11, the awareness address of the mobile terminal device 11, the home agent address of the mobile terminal device 11, and the like recorded in the join cache table. Will be described.

Upon receiving this extended join response message, the external agent 62 generates a join cache table for the mobile terminal device 11 based on the contents of the extended portion of the extended join response message. Then, the external agent 62 sends a join request message to the home agent 13 in order to notify the new awareness address of the remote terminal device 41. As a result, the IP tunnel 23 from the external agent 62 to the external agent 32 is formed.

[0148] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0149] As described above, this<u style="single">Embodiment 1</u>According to the report, when the remote terminal device 41 moves across the IP networks 3,5,6, the external agents 32,52,62 of the destination IP network 3,5,6 move to the source IP network 3. Since the registration information of the join cache table is acquired from the external agents 32,52,62 of 5,6 and recorded in its own join cache table, the occurrence of temporary triangular routing is suppressed and the route is optimized. The effect is that you can continue.

【0150】<u style="single">Reference example 13</u>. Of this invention<u style="single">Reference example 13</u>The external agents 32,52,62 in the above monitor the amount of IP packets sent and received between the remote terminal device 41 and the mobile terminal device 11 belonging to the own IP network 3,5,6, and adjust to those amounts. Correspondingly, the notice address registered in the join cache table for the mobile terminal device 11 is not updated.

[0151] Above<u style="single">Reference Examples 1 to 12, Embodiment 1</u>In the external agents 32, 52, 62, even if the remote terminal device 41 does not send an IP packet, when the notice address of the mobile terminal device 11 is registered in the join cache table, the notice address is periodically set. Update. Therefore, the awareness address of the mobile terminal device 11 which is the destination of the IP packet infrequently is also updated periodically.

[0152] So, this<u style="single">Reference example 13</u>The external agents 32, 52, 62 in the above are intended to suppress the update of the noticed address of the mobile terminal device 11 which is the destination of the IP packet infrequently.

[0153] Next, the operation will be described. The external agents 32,52,62 of the IP network 3,5,6 to which the remote terminal device 41 currently belongs reads the destination IP address and the source IP address of the received packet, and the mobile terminal device 11 and the remote terminal device 41 Calculate the traffic volume of IP packets to and from at any time.

[0154] Then, the external agents 32, 52, 62 stop transmitting the join request message and join when there is no IP packet traffic between the mobile terminal device 11 and the remote terminal device 41 for a predetermined period. Stop updating the noticed address in the cache table.

[0155] For other operations,<u style="single">Reference example 1</u>Since it is the same as that according to the above, the description thereof will be omitted.

[0156] As described above, this<u style="single">Reference example 13</u>According to the external agents 32,52,62, the amount of IP packets destined for the mobile terminal device 11 and the amount of IP packets from the mobile terminal device 11 are monitored, and the mobile terminal device 11 is combined according to the amount. Since the update of the notice address registered in the cache table is suppressed, the effect of reducing the amount of communication packets for sending and receiving messages between the external agents 32,52,62 and the home agent 13 can be reduced. Is obtained.

【0157】<u style="single">Embodiment 2</u>. Of this invention<u style="single">Embodiment 2</u>The external agents 32,52,62 in the above are those that do not update the awareness address registered in the join cache table when the remote terminal device 41 moves out of its own IP network 3,5,6. ..

[0158] Next, the operation will be described. In the network of FIG. 25, when the remote terminal device 41 moves from the IP network 5 of the external agent 52 to the IP network 6 of the external agent 62, the join update message from the external agent 62 to the external agent 52 is shown as shown in FIG. 28. Is sent.

[0159] As a result, the external agent 52 detects that the remote terminal device 41 has moved out of its own IP network 5. Further, even if the join update message is not sent to the external agent 52, the external agent 52 causes the other party terminal device 41 to be outside its own IP network 5 when the notice address of the other party terminal device 41 becomes invalid. Judge that it has moved to.

[0160] When the remote terminal device 41 moves out of its own IP network 5, the external agent 52 needs to tunnel the IP packet from the remote terminal device 41 to the noticed address of the mobile terminal device 11 thereafter. If it is determined that the remote terminal device 41 has moved out of its own IP network 5, the update of the noticed address in the join cache table is stopped.

[0161] As described above, this<u style="single">Embodiment 2</u>According to the report, when the remote terminal device moves across IP networks 3,5,6, the external agents 32,52,62 of the source IP network 3,5,6 are registered in the join cache table. Since the awareness address is not updated, the effect of reducing the amount of communication packets for sending and receiving messages between the external agents 32, 52, 62 and the home agent 13 can be obtained.

【0162】<u style="single">Embodiment 3</u>. Of this invention<u style="single">Embodiment 3</u>The external agents 32, 52, 62 in the above are designed to restart the update of the notice address that stopped the update when the predetermined conditions are satisfied.

[0163] Next, the operation will be described. External agents 32,52,62<u style="single">Reference example 13</u>Or<u style="single">Embodiment 2</u>When a combined update message for the noticed address whose update has been stopped is received as shown in, or when a tunnel transfer is performed to the noticed address, the update of the noticed address is restarted.

[0164] As described above, this<u style="single">Embodiment 3</u>According to the report, when the predetermined conditions are satisfied, the update of the awareness address that stopped the update is restarted, so that the update of the awareness address is executed at an appropriate frequency as needed, and the external agent 32,52 The effect of reducing the amount of communication packets for sending and receiving messages between the 62 and the home agent 13 can be obtained.

[0165] In the above embodiment, the functions of the external agents 32, 42, 62 and the functions of the home agents 13, 43 have been described separately, but the external agent for the terminal device that does not belong to the home agents 13, 43 has been described separately. Of course, you may add the function of to home agents 13,43.

[Effect of the Invention] As described above, according to the present invention,<u style="single">When the other party terminal device moves to its own network domain, the external agent acquires the information of the notice address of the mobile terminal device from the external agent or home agent of the network domain from which the other party terminal device is moved, or When the external agent or home agent moves to its own network domain, the external agent or home agent acquires the information of the notice address of the mobile terminal device from the external agent of the network domain from which the remote terminal device is moved.</u>Therefore, there is an effect that it is possible to suppress the occurrence of temporary triangular routing and continue the route optimization.

[0167] According to the present invention, when the external agent or home agent of the network domain to which the remote terminal device currently belongs moves the remote terminal device to the outside of its own network domain, the notice address of the mobile terminal device is updated. By stopping, it is possible to reduce the amount of communication packets for sending and receiving messages between the external agent or home agent of the network domain to which the other terminal device currently belongs and the home agent of the mobile terminal device. effective.

[0168] According to the present invention.<u style="single">Of the network domain to which the other terminal device currently belongs</u>The external agent or home agent stopped updating when certain conditions were met.<u style="single">Of mobile terminal devices</u>Since the update of the awareness address is restarted, the update of the awareness address is executed at an appropriate frequency as needed, and the external agent or home agent of the network domain to which the remote terminal device currently belongs and the home agent of the mobile terminal device are updated. It has the effect of reducing the amount of communication packets for sending and receiving messages to and from.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] The present invention<u style="single">Reference example 1</u>It is a figure which shows an example of the network which applied the route optimization method by.

FIG. 2 is an SDL diagram illustrating the operation of an external agent.

FIG. 3 is a diagram showing an example of a connected terminal management table held by an external agent to which a mobile terminal device is connected.

FIG. 4 is a diagram showing an example of a join cache table held by an external agent to which the remote terminal device is connected.

FIG. 5 is an SDL diagram illustrating the operation of the remote terminal device.

FIG. 6 is an SDL diagram illustrating the operation of a mobile terminal device.

FIG. 7 is an SDL diagram illustrating the operation of a home agent.

FIG. 8 is a diagram showing an example of an awareness address management table possessed by a home agent for a mobile terminal device.

FIG. 9 is a diagram showing a sequence of registration of a noticed address of a mobile terminal device and packet transmission.

FIG. 10 of the present invention<u style="single">Reference example 3</u>It is a figure which shows an example of the network which applied the route optimization method by.

[Fig. 11] <u style="single">Reference example 3</u>It is a figure which shows an example of the extended join request message in.

FIG. 12 is a diagram showing an example of an HA support table.

FIG. 13 is an SDL diagram illustrating an operation when a home agent capable of interpreting an extended join request message receives a join request message.

FIG. 14 is a diagram showing an example of an HA support table in which a subnet mask is introduced.

FIG. 15 is a diagram showing an example of a join update message when the HA support table is dynamically set.

FIG. 16 is a diagram showing an example of an internal table in which a limited number of home agents are recorded.

FIG. 17 is a diagram showing an example of an internal table in which grouping by subnet mask is introduced.

FIG. 18 is a diagram showing an example of a service setting table.

[Fig. 19] IP packet received<u style="single">Reference example 8</u>It is an SDL diagram explaining the operation of an external agent in.

FIG. 20 is a diagram showing an example of a service setting table in which a subnet mask is introduced.

FIG. 21 is an SDL diagram illustrating an operation in which an external agent adjusts the transmission interval of a join request message.

[Fig. 22] This<u style="single">Reference example 10</u>It is a figure which shows the join cache table of the external agent in.

[Fig. 23] This<u style="single">Reference example 11</u>It is a figure which shows an example of the service setting table which an external agent has in.

[Fig. 24] <u style="single">Reference example 12</u>It is a figure which shows an example of the extended join update message in.

FIG. 25 is a diagram showing a network when the remote terminal device 41 moves to another IP network in the network shown in FIG.

[Fig. 26] <u style="single">Embodiment 1</u>It is an SDL diagram explaining the operation of an external agent in.

[Fig. 27] <u style="single">Embodiment 1</u>It is an SDL diagram explaining the operation of an external agent in.

FIG. 28 is a diagram showing a sequence of operations of each device and an agent when the other terminal device moves to another IP network.

[Fig. 29] <u style="single">Embodiment 1</u>It is a figure which shows an example of the combined response message extended in.

FIG. 30 is a diagram illustrating packet transmission with a conventional Mobile IP.

FIG. 31 is a diagram illustrating route optimization in a conventional Mobile IP.

[Code description] 1,3 ~ 6 IP network (network domain), 13,43 Home agent (agent device), 32,52,62 External agent (agent device), 11,11-1,11-2 Mobile terminal Device, 41,41-1,41-2 Remote terminal device.