JP2010021713A - Proxy terminal, communication method, and communication program - Google Patents

Abstract

An object of the present invention is to enable a mobile terminal to immediately perform data communication with a partner terminal even immediately after the mobile terminal moves from a remote to a local network.
A proxy terminal according to an aspect of the present invention is a proxy terminal connected to a first network, the second network connected to the first network via one or more routers. Means for generating correspondence information in which the MAC address of the mobile terminal is associated with the IP address of the mobile terminal used on the first network in response to a request from the upper mobile terminal; Means for monitoring data flowing over and detecting a MAC address inquiry request based on the IP address of the mobile terminal used in the first network; and a MAC address corresponding to the IP address included in the inquiry request Is specified from the correspondence information, and is returned to the request source of the inquiry.
[Selection] Figure 6

Description

  The present invention relates to a proxy terminal, a communication method, and a communication program, for example, a proxy terminal that responds to an inquiry such as an ARP request on behalf of a remote mobile terminal.

  In order to make the mobile terminal that is remotely accessed appear to exist in the local network, the local network responds to the ARP inquiry (ARP request) from the communication partner terminal instead (ARP response). There is a proxy terminal. A method of responding to ARP as a proxy is called Proxy ARP, and is defined in RFC1027. The proxy terminal responds to the ARP using its own MAC address, and instead receives communication data addressed to the mobile terminal and transfers it to the mobile terminal. When the communication partner terminal receives the ARP response message, the communication partner terminal holds a table called an ARP cache that associates the destination IP address of the communication data with the MAC address for a certain period of time. By holding the ARP cache, it is not necessary to send an ARP request every time communication data is sent within the valid time of the cache.

  However, when a mobile terminal that is accessing remotely moves through the network and enters the local network, the communication partner terminal holds the ARP cache, and the IP address and the MAC address of the proxy terminal are associated with each other. As long as the ARP cache does not disappear, communication data addressed to the mobile terminal is transmitted to the proxy terminal. The proxy terminal does not reach the mobile terminal as long as there is no means for transferring the communication data even though the mobile terminal exists in the local network. Therefore, when the mobile terminal moves to the local network, it broadcasts a message called Gratuitous ARP requesting the update of the MAC address for its own IP address. The terminal in the local network that has received this ARP updates the ARP entry of the mobile terminal existing in the ARP cache to the association between the mobile terminal's MAC address and IP address. As a result, the communication partner terminal can quickly transmit the communication data to the mobile terminal by updating the ARP cache. Gratuitous ARP is defined in RFC925.

In IPv6, using NDP (Neighbor Discovery Protocol) instead of ARP, it is possible to do the same as IPv4 ARP.
RFC925 (Proxy ARP)

  However, updating the ARP cache quickly causes a problem from the viewpoint of security. For example, in an attack technique called ARP poisoning, a malicious attack terminal responds to an ARP request from a communication partner terminal with a fake ARP response instead, updates the ARP cache of the communication partner terminal, and sends it to its own MAC address. By allowing the communication data to be sent, it is possible to easily intercept the communication. Effective countermeasures against ARP poisoning include a method of statically fixing the ARP cache of each terminal in the local network, an illegal ARP response is monitored, and the monitoring result is updated before the ARP cache is updated after each terminal receives it. In either case, the update of the ARP cache is not accelerated. Therefore, when an application such as VoIP or video service is used, communication data may not arrive for a while after the mobile terminal moves from remote to local until the ARP cache is updated.

  Therefore, in the present invention, the proxy terminal that solves the above-described problems of the prior art and enables the mobile terminal to immediately perform data communication with the counterpart terminal immediately after the mobile terminal moves from the remote to the local network. A communication method and a communication program are provided.

The proxy terminal as one aspect of the present invention is:
A proxy terminal connected to the first network,
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network Correspondence information generating means for generating correspondence information in association with the IP address of the terminal;
Storage means for storing the generated correspondence information;
Detecting means for monitoring data flowing on the first network and detecting an inquiry request for a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. Proxy response means to reply on behalf of the device;
It is provided with.

A communication method as one aspect of the present invention includes:
A communication method executed in a computer connected to a first network, comprising:
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network A correspondence information generation step of generating correspondence information in which the IP address of the terminal is associated;
A storage step for storing the generated correspondence information;
A detecting step of monitoring data flowing on the first network and detecting an inquiry request of a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. A proxy response step to reply on behalf of the device;
It is provided with.

A communication program as one aspect of the present invention is:
A communication program executed in a computer connected to a first network,
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network A correspondence information generation step of generating correspondence information in which the IP address of the terminal is associated;
A storage step for storing the generated correspondence information;
A detecting step of monitoring data flowing on the first network and detecting an inquiry request of a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. A proxy response step to reply on behalf of the device;
Is executed by a computer.

  According to the present invention, even after a mobile terminal moves from a remote to a local network, the mobile terminal can quickly perform data communication with a partner terminal.

  Embodiments of a proxy terminal according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a configuration of a network system provided with a proxy terminal as one embodiment of the present invention. The home agent 112, the MPA (Media Independent Pre-Authentication) agent 122, and the MPA agent 132 correspond to the proxy terminal according to the embodiment of the present invention.

  Mobile terminal (communication terminal) 100, home agent 112, and access point 113 are connected to network 110. The mobile terminal 100 is connected to the access point 113 via a wireless LAN (Local Area Network). The network 110 is connected to the Internet 103 via the router 111.

  The partner terminal 101 and the information server 102 exist in an arbitrary network on the Internet 103.

  An access point 123, an MPA agent 122, and a DHCP (Dynamic Host Configuration Protocol) server 124 are connected to the network 120 and connected to the Internet 103 via the router 121.

  The access point 133, the MPA agent 132, and the DHCP server 134 are connected to the network 130 and connected to the Internet 103 via the router 131.

  For the mobile terminal 100, the network 110 is a mobile IP (Internet Protocol) home network, and the other networks 120 and 130 are visited networks.

  The mobile terminal 100 communicates with the counterpart terminal 101 by TCP / IP (Transmission Control Protocol / Internet Protocol). At this time, the IP address of the mobile terminal 100 uses the home address assigned by the home agent.

  In the following, the mobile terminal 100 in the state of FIG. 1 hands over to the access point 123 in the network 120 as shown in FIG. 9, then hands over to the access point 133 in the network 130 as shown in FIG. Again, the configuration and operation of each element in the network system of FIG. 1 will be described by taking as an example the case of handing over to the access point 113 in the network 110. FIG. 8 shows a message sequence when the mobile terminal 100 is handed over from the access point 112 to the access point 123, FIG. 14 shows a message sequence when handing over from the access point 123 to the access point 133, and FIG. FIG. 16 shows a message sequence at the time of handover, and description will be given with reference to FIGS. 8, 15 and 16 as appropriate.

  FIG. 2 is an internal configuration diagram of the mobile terminal 100.

  The mobile terminal 100 includes a wireless LAN interface 1001, a TCP / IP protocol stack 1002, a mobile IP client 1003, a MIH (Media Independent Handover) client 1004, an authentication client 1005, and an MPA client 1006.

  The MPA client 1006 examines the RSSI (Received Signal Strength Indicator) of the wireless LAN interface 1001. When the physical distance from the access point 113 increases, the RSSI decreases, so that the handover is performed to another access point. In response to a request to the information server 102, neighboring access point information is acquired using, for example, the IEEE 802.21 MIH protocol.

  FIG. 3 is an example of the format of an information acquisition request / response message of the IEEE 802.21 MIH (Media Independent Handler) protocol.

  The information acquisition request message 2000 includes an IP header, a UDP header, an MIH header, and a query. The MIH header is composed of an ID indicating a message type, a transaction ID indicating a query number, and the like. In the query, the BSSID of the currently connected access point is registered as a search key, the IP address of the MPA agent, the channel of the access point, the BSSID, etc. are registered as the type of request data.

  The information acquisition response message 2001 includes an IP header, a UDP header, an MIH header, and a query response. The transaction ID of the MIH header is the same ID number as the corresponding information acquisition request message 2000. The query response stores the IP address of the MPA agent, the channel of the access point, and the BSSID as search results.

  When the RSSI of the wireless LAN interface 1001 is lowered to a certain level, the MPA client 1006 makes an information acquisition request to the MIH client 1004, and the MIH client 1004 creates an information request query and transmits information through the TCP / IP protocol stack 1002. An information acquisition request message 2000 is transmitted to the server 102 (S11 in FIG. 8). The IP address of the information server 102 is acquired using a DNS service or the like.

  FIG. 4 is an internal configuration diagram of the information server 102.

  The information server 102 includes a LAN interface 1021, a TCP / IP protocol stack 1022, an MIH server 1023, and a network information DB 1024.

  When the MIH server 1023 receives the information acquisition request message 2000 via the LAN interface 1021 and the TCP / IP protocol stack 1022, the MIH server 1023 searches the network information DB 1024 using a query, and an information acquisition response based on the obtained answer A message 2001 is created and transmitted to the mobile terminal 100 via the TCP / IP protocol stack 1022 and the LAN interface 1021 (S12 in FIG. 8).

  In this example, it is assumed that the obtained IP address of the MPA agent is that of the MPA agent 122 in the network 120, the channel of the access point, and the BSSID are those of the access point 123.

  Next, the MPA client 1006 in the mobile terminal 100 makes an authentication request to the MPA agent 122 in the network 120 using the authentication client 1005 (S13 in FIG. 8). For example, for example, the Radius protocol or the PANA protocol can be used for authentication.

  FIG. 5 is an internal configuration diagram of the MPA agent 122 or 132.

  The MPA agent includes a LAN interface 1221, a TCP / IP protocol stack 1222, a DHCP relay client 1223, an authentication server 1224, an MPA server 1225, and a table 1226.

  The authentication request message received from the mobile terminal 100 is processed by the authentication server 1224. The authentication server 1224 extracts the MAC (Media Access Control) address of the wireless LAN interface 1001 of the mobile terminal 100 from the received authentication request message, and transmits the MAC address to the DHCP relay client 1223 via the MPA server 1225.

  The DHCP relay client 1223 makes an IP address acquisition request to the DHCP server 124 (S14 in FIG. 8), and receives the IP address from the DHCP server 124 (S15 in FIG. 8).

  The MPA server 1225 registers the obtained IP address and the MAC address received from the authentication server 1224 in the table 1226 in association with each other. The table 1226 corresponds to a storage unit that stores correspondence information in which, for example, the MAC address of the mobile terminal is associated with the IP address of the mobile terminal used in the network 120. The MPA server 1225 includes correspondence information generating means for generating correspondence information. Similarly, the MPA server 1225 in the MPA agent 132 includes correspondence information generation means for generating correspondence information, and the MPA agent 132 includes storage means for storing the correspondence information.

  The authentication server 1224 transmits the IP address assigned from the DHCP server 124 to the mobile terminal 100 together with the authentication completion message (S16 in FIG. 8).

  The mobile terminal 100 that has received the authentication completion message connects to the access point 123 in the network 120 via a wireless LAN. If the connection is successful, the mobile terminal changes the IP address to that obtained at the time of authentication, and transmits a mobile IP registration request message (care-of address update request message) 3000 shown in FIG. 7 to the home agent 112 ( S17 in FIG.

  As shown in FIG. 7, the message 3000 is provided with a uniquely defined option (MAC address expansion unit 3001) for storing the MAC address. The MAC address extension unit 3001 is a unique extension unit defined for the present invention, and is added to the end of a registration request message used in normal mobile IP. The MAC address extension unit 3001 includes a type, a length, and a MAC address. The type is a unique value, the length is a length value of the MAC address, and the MAC address is a MAC address of the mobile terminal. Yes.

  FIG. 6 shows an internal configuration diagram of the home agent 112.

  The home agent 112 includes a LAN interface 1121, a TCP / IP protocol stack 1122, a mobile IP server 1123, and a table 1124.

  When receiving the registration request message 3000 from the mobile terminal 100 via the LAN interface 1121 and the TCP / IP protocol stack 1122 (S17 in FIG. 8), the mobile IP server 1123 authenticates the message. The mobile IP server 1123 registers the IP address as the home address and the MAC address obtained from the MAC address extension unit in FIG. 7 in the table 1124, and a mobile IP registration response message is newly obtained for the mobile terminal 100. Transmission is made to the IP address (S18 in FIG. 8). The table 1124 corresponds to storage means for storing correspondence information in which, for example, the MAC address of the mobile terminal is associated with the IP address of the mobile terminal used in the home network 110. The mobile IP server 1123 includes correspondence information generating means for generating correspondence information. Thereafter, the mobile IP server 1123 creates a mobile IP tunnel with the mobile terminal 100 (S19 in FIG. 8).

  On the other hand, the mobile terminal 100 that has received the registration response message also creates a mobile IP tunnel with the mobile IP server 1123 in the home agent 112 using the home address (S19 in FIG. 8).

  FIG. 11 shows the relationship between the IP packet between the mobile terminal 100 and the counterpart terminal 101 and the mobile IP tunnel.

  The IP packet transmitted from the partner terminal 101 is an IP packet whose source is the IP address of the partner terminal 101 and whose destination is the home address, and is transferred to the router 111. The router 111 makes an ARP request when there is no IP address corresponding to an ARP (Address Resolution Protocol) cache. The home agent 112 sends a proxy ARP response to the router 111 with the MAC address of the mobile terminal 100. The LAN interface 1121 in the home agent 112 includes a detecting unit that detects a MAC address inquiry request (ARP request) based on the IP address of the mobile terminal 100, and a MAC address corresponding to the IP address included in the detected ARP request. Proxy response means that identifies from the table 1124 and returns an inquiry response including the identified MAC address to the inquiry source of the ARP request.

  The home agent 112 receives the IP packet from the router 111 as a proxy. The LAN interface 1121 of the home agent 112 operates in the promiscuous mode, receives all frames flowing on the network 110 (LAN), queries the table 1124, and frames addressed to the MAC address of the mobile terminal 100 are TCP / IP. The packet is transmitted to the protocol stack 1222, and the TCP / IP protocol stack 1222 performs encapsulation using the IP header by tunneling, and transmits the IP-encapsulated packet 4000 to the mobile terminal 100 via the LAN interface 1221. The LAN interface 1121 includes second detection means for monitoring data flowing on the network 110 and detecting communication data destined for the MAC address of the mobile terminal 100. The TCP / IP protocol stack 1122 includes transfer means for transferring the detected data to the mobile terminal 100 by encapsulation. The transmission source of the IP header outside 4000 of the IP-encapsulated packet is the address of the home agent 112, and the transmission destination is a registered care-of address on the network 120 of the mobile terminal 100. The detailed structure of the encapsulated packet 4000 transmitted from the home agent 112 to the mobile terminal 100 is shown in FIG.

  As shown in FIG. 10A, a packet transmitted from the partner terminal 101 to the home agent 112 is indicated by 4000d, and this packet 4000d is encapsulated by the IP header 4000a, so that the IP encapsulated packet 4000 is homed. It is transmitted from the agent 112 to the mobile terminal 100. That is, an IP packet 4000d composed of an inner IP header 4000b and communication data 4000c is transmitted from the counterpart terminal 101 to the home agent 112, and the outer IP header 4000a is added at the home agent to the care-of address of the mobile terminal 100. Sent.

  On the other hand, for a packet transmitted from the mobile terminal 100, each router shown in FIG. 1 checks the source IP address and transfers only an IP packet having the IP address in its own network as the source. Also, transmission from the mobile terminal 100 needs to be IP-encapsulated. In the present embodiment, it is assumed that the mobile terminal 100 also encapsulates the transmission packet in IP. In that case, the mobile terminal 100 creates and transmits an IP-encapsulated IP packet 4001 as shown in FIG. In the inner IP header 4001b, the source is the home address of the mobile terminal 100, and the destination is the address of the partner terminal 101. In the outer IP header 4001a, the source is the care-of address of the mobile terminal 100, and the destination is the address of the home agent 112. As a result, the packet 4001 is received by the home agent 112, the outer IP header 4001a is removed, and the inner IP packet 4001d is transmitted to the counterpart terminal 101.

  When the mobile terminal 100 moves again and moves away from the access point 123 to detect that the RSSI has decreased, the mobile terminal 100 transmits an information acquisition request message to the information server 102 (S21 in FIG. 14), and receives an information acquisition response message. Is obtained from the information server 102 (S22 in FIG. 14).

  It is assumed that the IP address of the MPA agent 132 of the network 130, the channel of the access point 133, and BSSID information are obtained from the response message as destination candidates.

  Therefore, the mobile terminal 100 issues an authentication request to the MPA agent 132 (S23 in FIG. 14), as was done for the network 120 during the previous movement (S23 in FIG. 14), and the MPA agent 132 obtains an IP address from the DHCP server 134. (S24, S25 in FIG. 14), an authentication completion message is transmitted to the mobile terminal (S26 in FIG. 14).

  Next, the MPA client 1006 of the mobile terminal transmits an MPA tunnel creation request message to the MPA agent 132 so as to create an MPA tunnel using the obtained new IP address (S27 in FIG. 14).

  Upon receiving the message, the MPA agent 132 creates and transmits an MPA tunnel creation response message (S28 in FIG. 14), and creates an MPA tunnel with the mobile terminal 100 (S29 in FIG. 14). On the other hand, when the mobile terminal 100 also receives the MPA tunnel creation response message, it creates an MPA tunnel with the MPA agent 132 (S29 in FIG. 14).

  The MPA agent 132 sets the LAN interface 1221 in promiscuous mode, receives all frames flowing on the network 130 (LAN), refers to the table 1226, detects frames addressed to the mobile terminal MAC address, and detects them. Transmits to the TCP / IP protocol stack 1222 and deletes other frames. An IP packet having a new IP address as a transmission source transmits a frame in the LAN interface 1221 by referring to the table 1226 and using the MAC address of the mobile terminal 100 as a transmission source. The MPA agent 132 responds to the ARP request for a new IP address such as the router 131 with the MAC address of the mobile terminal 100. The LAN interface 1121 in the MPA agent 132 includes detection means for detecting a MAC address inquiry request (ARP request) based on the IP address of the mobile terminal 100, and a MAC address corresponding to the IP address included in the detected ARP request. Proxy response means that identifies from the table 1124 and returns an inquiry response including the identified MAC address to the inquiry source of the ARP request. Similarly, the LAN interface 1121 in the MPA agent 122 includes detection means and proxy response means.

  Furthermore, the mobile terminal 100 transmits a registration request message to the home agent 112 (S30 in FIG. 14). The home agent 112 transmits a registration response message to the mobile terminal 100 (S31 in FIG. 14). As a result, the mobile IP tunnel is recreated between the home agent 112 and the mobile terminal 100, and the communication data path is changed.

  FIG. 13 shows a state where the mobile IP tunnel is recreated and the MPA tunnel is created between the MPA agent 132 and the mobile terminal 100.

  Communication data transmitted from the partner terminal 101 is received by the home agent 112 as a proxy, transferred to the network 130 via the mobile IP tunnel, and received by the MPA agent 132 as a proxy. The MPA agent 132 further IP-encapsulates the IP-encapsulated packet and transmits it to the mobile terminal 100 via the MPA tunnel. The LAN interface 1121 in the MPA agent 132 includes second detection means for monitoring data flowing on the network 110 and detecting communication data destined for the MAC address of the mobile terminal 100. The IP protocol stack 1222 includes transfer means for transferring the detected data to the mobile terminal 100 by encapsulation. Similarly, the LAN interface 1121 in the MPA agent 122 includes second detection means, and the TCP / IP protocol stack 1222 includes transfer means.

  FIG. 12A shows a format of a packet transmitted to the mobile terminal 100 in this state.

  The IP packet 5000e transmitted from the counterpart terminal 101 is received by the home agent 112, and the home agent 112 has the new care-of address as the care-of address on the network 130 as the destination and the IP address of the home agent 112 as the sender. The IP packet 5000e is encapsulated by the IP header 5000b, and the encapsulated packet 5000f is transferred. This packet 5000f is transmitted to the router 131, and when a frame is transmitted to the MAC address of the mobile terminal 100 by ARP, the MPA agent 132 responds by proxy ARP and receives the MAC address of the mobile terminal 100. In order to transfer the IP packet 5000f to the mobile terminal 100, the MPA agent 132 is further encapsulated by the IP header 5000a and transmitted as a double IP encapsulated packet 5000. The source address of the IP header 5000a is the IP address of the MPA agent 132, and the destination IP address is the IP address used by the mobile terminal 100 in the network 120.

  On the other hand, the packet transmitted from the mobile terminal 100 is a double IP encapsulated packet 5001 as shown in FIG. In this packet 5001, the source address of the outermost IP header 5001a is the care-of address on the network 120 of the mobile terminal 100, the destination is the address of the MPA agent 132, and the source address of the inner IP header 5001b is The new care-of address obtained from the network 130 by the mobile terminal 100, the transmission destination is the home agent 112, and the innermost IP header 5001c has the home address of the mobile terminal 100 as the transmission source and the destination terminal 101 as the transmission destination. When the packet 5001 transmitted from the mobile terminal 100 is first received by the MPA agent 132, the outer IP header 5001a is removed, and the packet 5001 is transferred to the home agent 112 based on the inner IP header 5001b. In the home agent 112, the IP header 5001b is further removed and transferred to the counterpart terminal 101 as a normal IP packet 5001e.

  As shown in FIG. 15, when handing over to the access point 133, the mobile terminal 100 transmits an MPA tunnel deletion request message to the MPA agent 132 (S32 in FIG. 14).

  Upon receiving the deletion request message, the MPA agent 132 deletes the entry of the MAC address and care-of IP address of the mobile terminal 100 from the table 1226, deletes the MPA tunnel, and transmits an MPA tunnel deletion response message (S33 in FIG. 14). ), Stop acting. That is, when the MPA agent 132 detects that the mobile terminal 100 is connected to the network 130, the MPA agent 132 performs setting so as to stop the proxy response. The MPA server 1225 in the MPA agent 132 includes third detection means for detecting that the mobile terminal 100 is connected to the network 130.

  Upon receiving this deletion response message, the mobile terminal 100 deletes the MPA tunnel and communicates using the care-of address obtained in the network 130.

  In this state, all nodes including routers on this network transmit packets to the mobile terminal 100 to the IP address addressed to the care-of address without the need to update the ARP cache.

  Packets transmitted and received in this state are IP-encapsulated packets as shown in FIGS. 10 (A) and 10 (B).

  That is, as shown in FIG. 10A, the packet transmitted from the partner terminal 101 is an IP packet 4000d in which the transmission source is the partner terminal 101 and the transmission destination is the home address of the mobile terminal 100. Received on behalf. The home agent 112 adds an IP header 4000a having the transmission source as the home agent 112 and the transmission destination as the care-of address of the network 130 of the mobile terminal 100, and transfers the IP header 4000a to the mobile terminal 100 as an IP encapsulated packet 4000.

  On the other hand, the IP packet transmitted from the mobile terminal 100 is an IP encapsulated packet 4001 having the format shown in FIG. 10B, and the inner IP header 4001b has the source as the home address of the mobile terminal 100 and the destination as the destination. The terminal 101 and the outer IP header 4001a are the care-of address of the mobile terminal 100 as the transmission source, and the address of the home agent 112 as the transmission destination. Accordingly, the packet 4001 is received by the home agent 112, the IP header 4001a is removed, and the inner IP packet 4001d is received by the counterpart terminal 101.

  As described above, at the time of handover using MPA as a framework, the update of the ARP cache does not occur on the network of the movement destination, so that the time for communication data delay and packet loss is reduced.

  Here, when the mobile terminal 100 further moves and the RSSI of the access point 133 decreases, an information acquisition request message is transmitted to the information server 102 (S41 in FIG. 16), and an information acquisition response message is received from the information server 102. (S42 in FIG. 16). In the received information acquisition response message, it is assumed that there is no MPA agent and the channel and BSSID of the access point 113 are obtained. As a result, the mobile terminal 100 is handed over to the access point 113 without performing the MPA process.

  When the handover is completed, the mobile terminal 100 transmits a registration request message to the home agent 112 and deletes the registration entry (S43 in FIG. 16).

  The home agent 112 receives the response message (S44 in FIG. 16) and detects that the mobile terminal 100 is connected to the network 110. Here, the home agent 112 deletes the entry of the home address and the MAC address existing on the table 1124 and stops the proxy work. The mobile IP server 1123 in the home agent 112 includes third detection means for detecting that the mobile terminal 100 is connected to the network 110.

  As described above, when the mobile terminal 100 returns to the home network 110, the ARP cache is not updated on the home network, so that the time for communication data delay and packet loss is reduced. By this movement, the communication path with the counterpart terminal 101 returns to the initial state, and the network at this time is the same as in FIG.

  The above description of the embodiment of the present invention is summarized as follows.

  While the mobile terminal is in a remote network different from the local network, the proxy terminal makes a proxy ARP response with the MAC address of the mobile terminal to the ARP request based on a table in which the MAC address and IP address of the mobile terminal are associated. In other words, the proxy ARP response is conventionally made with the MAC address of the proxy terminal, but in the embodiment of the present invention, the proxy response is made with the MAC address of the mobile terminal. As a result, the transmission source of the ARP request associates the MAC address of the mobile terminal with the IP address, updates the ARP cache, and transmits communication data to the MAC address of the mobile terminal. The communication data is received, and the received communication data is transferred to the communication terminal.

  When the mobile terminal moves to the local network, the movement is detected by Gratuitous ARP or the like. Thereafter, the proxy terminal makes a proxy ARP response with the MAC address of the mobile terminal, and receives and transfers communication data addressed to the MAC address of the mobile terminal. Stop.

  Note that ARP is an address resolution technique in IPv4, but in IPv6, the same can be done in NDP, and the ARP request is replaced by Neighbor Solitization, and the ARP response and Gratuitous ARP are replaced by Neighbor Advertisement.

  As described above, according to the embodiment of the present invention, communication data can be received immediately without address resolution immediately after the mobile terminal moves through the network. Then, the sound and the moving image are not interrupted even when moving.

  The proxy terminal (home agent, MPA agent) in the present embodiment described above can also be realized by using a general-purpose computer device as basic hardware, for example. That is, the LAN interface, TCP / IP protocol stack, and mobile IP server in the home agent, and the LAN interface, TCP / IP protocol stack, authentication server, MPA server, and DHCP relay client in the MPA agent are mounted on the computer device. This can be realized by causing a processor to execute a program. At this time, the proxy terminal may be realized by installing the above program in a computer device in advance, or may be stored in a storage medium such as a CD-ROM or distributed through the network. The program may be implemented by appropriately installing it in a computer device.

1 is a configuration diagram of an entire network when a proxy terminal according to an embodiment of the present invention is located in a mobile IP home network. The internal block diagram of the mobile terminal 100 based on embodiment of this invention Format diagram of information acquisition request message and information acquisition response message according to an embodiment of the present invention The internal block diagram of the information server 102 based on embodiment of this invention The internal block diagram of MPA agent 122,132 based on embodiment of this invention The internal block diagram of the home agent 112 based on embodiment of this invention Message format diagram of mobile IP registration request message and MAC address extension unit, according to an embodiment of the present invention Message sequence diagram until the mobile terminal 100 is handed over from the network 110 to the network 120 according to the embodiment of the present invention The whole network figure showing the state where the mobile terminal moved to the network 120 based on embodiment of this invention Message format diagram of IP encapsulated packet used for communication between mobile terminal 100 and counterpart terminal 101 immediately after moving to network 120 according to the embodiment of the present invention The figure which showed the relationship between the destination of the communication packet between the mobile terminal 100 and the other party terminal 101 immediately after movement to the network 120, and a mobile IP tunnel and the format of an IP packet based on embodiment of this invention. Message format diagram of a double IP encapsulated packet exchanged with the mobile terminal 100 creating an MPA tunnel according to an embodiment of the present invention According to the embodiment of the present invention, in a state where the mobile terminal 100 has created an MPA tunnel, the destination of the IP packet with the counterpart terminal 101, the point where the MPA tunnel and the mobile IP tunnel are created, and between each destination A diagram showing the relationship between the types of packets that flow Message sequence diagram until the mobile terminal 100 is handed over from the network 120 to the network 130 Overall network diagram showing a state after the mobile terminal 100 has moved to the network 130 Message sequence diagram until the mobile terminal 100 moves from the network 130 to the network 110

Explanation of symbols

100 mobile terminal 101 partner terminal 102 information server 103 internet 110, 120, 130 network 111, 121, 131 router 112 home agent (proxy terminal)
113, 123, 133 Access point 122, 132 MPA agent (proxy terminal)
124, 134 DHCP server 1001 Wireless LAN interface 1002, 1022, 1122, 1222 TCP / IP protocol stack 1003 Mobile IP client 1004 MIH client 1005 Authentication client 1006 MPA client 1021, 1221, 1121 LAN interface 1023 MIH server 1024 Network information DB
1123 Mobile IP Server 1124, 1226 Table 1223 DHCP Relay Client 1224 Authentication Server 1225 MPA Server 2000 Information Acquisition Request Message 2001 Information Acquisition Response Message 3000 Registration Request Message 3001 MAC Address Each Extension 4000, 4001 IP Encapsulated Packet 5000, 5001 Double IP encapsulated packet

Claims (6)

A proxy terminal connected to the first network,
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network Correspondence information generating means for generating correspondence information in association with the IP address of the terminal;
Storage means for storing the generated correspondence information;
Detecting means for monitoring data flowing on the first network and detecting an inquiry request for a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. Proxy response means to reply on behalf of the device;
Proxy terminal with Second detection means for monitoring data flowing on the first network and detecting communication data destined for the specified MAC address;
The proxy terminal according to claim 1, further comprising: a transfer unit that transfers the detected communication data to the mobile terminal on the second network. Further comprising third detecting means for detecting that the mobile terminal is connected to the first network;
The detection means, the proxy response means, the second detection means, and the transfer means stop processing for the mobile terminal when the connection of the mobile terminal is detected by the third detection means. The proxy terminal according to claim 2. The said correspondence information generation means acquires the MAC address of the said mobile terminal by receiving the MAC address information of the said mobile terminal from the mobile terminal on the said 2nd network. The Claim 1 thru | or 3 characterized by the above-mentioned. The proxy terminal according to any one of the above. A communication method executed in a computer connected to a first network, comprising:
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network A correspondence information generation step of generating correspondence information in which the IP address of the terminal is associated;
A storage step for storing the generated correspondence information;
A detection step of monitoring data flowing on the first network and detecting an inquiry request for a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. A proxy response step to reply on behalf of the device;
A communication method comprising: A communication program executed in a computer connected to a first network,
In response to a request from a mobile terminal on a second network connected to the first network via one or more routers, the mobile terminal uses the MAC address and the mobile to be used on the first network A correspondence information generation step of generating correspondence information in which the IP address of the terminal is associated;
A storage step for storing the generated correspondence information;
A detection step of monitoring data flowing on the first network and detecting an inquiry request for a MAC address based on an IP address of the mobile terminal used in the first network;
When the inquiry request is detected, a MAC address corresponding to the IP address included in the inquiry request is identified from the correspondence information, and an inquiry response including the identified MAC address is transferred to the inquiry request source. A proxy response step to reply on behalf of the device;
A program that causes a computer to execute.

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