JP2011135243A - Handover method of mobile terminal through ip network, system, access gateway, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a handover method etc., of a mobile terminal which prevents the loss of a data packet to the mobile terminal without going through an LMA, in a proxy mobile IPv6. <P>SOLUTION: A movement source MAG (Mobile Access Gateway) transmits a handover start message in the mobile terminal to a movement destination MAG. Then, the movement source MAG establishes an IP tunnel for data forwarding with respect to the movement destination MAG. Then, the mobile terminal performs handover from the movement source MAG to the movement destination MAG. The movement destination MAG simultaneously transmits to the IP network an update message including a network prefix held by the mobile terminal. When the movement source MAG receives the update message through the IP network, a succeeding hop gateway with respect to the network prefix of the mobile terminal is kept as the movement destination MAG, and the IP tunnel is disconnected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a handover technique for a mobile terminal via an IP (Internet Protocol) network.

  The next-generation all-IP mobile network is configured as a system in which a plurality of different access networks are accommodated in the IPv6 Internet. The terminal is connected to the Internet via an access network. An access gateway is interconnected between each access network and the Internet. Handover of a mobile terminal is realized by connecting from a source access gateway to a destination access gateway. At this time, it is necessary to switch the transfer destination of the data packet that is the destination of the mobile terminal from the source access gateway to the destination access gateway as network path control.

  Conventionally, there is a “mobile IPv6” technique as an IPv6 protocol that supports movement of a mobile terminal. According to this technology, a mobile terminal needs to implement Mobile IPv6, and a fixed home address is assigned to the mobile terminal. Thereby, the movement of the mobile terminal can be concealed as seen from the application.

  On the other hand, the technology of “Proxy Mobile IPv6” (hereinafter referred to as “PMIP” (Proxy Mobile IPv6)) in which the mobile terminal itself processes all mobility support on the network side without implementing a mobility management protocol. (See Non-Patent Document 1, for example).

  FIG. 1 is a system configuration diagram showing PMIP handover.

  According to FIG. 1, a plurality of different access networks 5 are connected to the Internet 4, and both networks are interconnected via an access gateway (hereinafter referred to as “MAG” (Mobile Access Gateway)). The mobile terminal 2 is connected to the access network 5 and connected to the Internet 4 via the MAG 1.

  The Internet 4 includes an IPv6 core network 41 and a transport network 42. In the case of PMIP, the transport network 42 is configured as a proxy mobile IPv6 domain network. Both networks are interconnected via a home agent (hereinafter referred to as “LMA” (Local Mobility Anchor)) 3. All data packets transmitted and received by the mobile terminal are transferred via the LMA.

  As Internet route control, the home address of a mobile terminal is linked to an LMA address (binding). The LMA 3 establishes a bidirectional data forwarding tunnel with the MAG 1. This tunnel is established by an LMA address and a proxy care of address.

  When the MAG 1 is connected from the mobile terminal 2 via the access network, the MAG 1 transmits the destination information of the mobile terminal 2 to the LMA 3. As a result, the LMA 3 processes location registration for the mobile terminal 2. That is, the LMA 3 transmits the data packet addressed to the mobile terminal 2 to the MAG 1 whose location is registered. As a result, the mobile terminal 2 can continue to use the same IP address before and after the handover.

  However, according to PMIP, it is necessary to switch from a tunnel established between the source MAG1A and LMA3 to a tunnel to be established between the destination MAG1B and LMA3. During the switching of the tunnel, a data packet addressed to the mobile terminal may be lost.

  On the other hand, there is a technique of proxy fast mobile IPv6 (hereinafter referred to as “PFMIP” (Proxy Fast Mobile IPv6)) that realizes further seamless communication (for example, see Non-Patent Document 2).

  FIG. 2 is a system configuration diagram showing a PFMIP handover.

  FIG. 2 shows a Predictive type fast handover method. According to this technique, during the handover of the mobile terminal 2, an IP tunnel for data forwarding is established between the source MAG1A and the destination MAG1B. The source MAG1A transfers the data packet addressed to the mobile terminal 2 received during the handover of the mobile terminal 2 to the destination MAG1B via the IP tunnel. The destination MAG1B temporarily buffers the data packet received via the IP tunnel without immediately transferring it to the mobile terminal 2. Then, when the mobile terminal 2 connects to the destination MAG1B, the destination MAG1B transmits the buffered data packet to the mobile terminal 2. As a result, loss of data packets addressed to the mobile terminal during handover of the mobile terminal can be prevented as much as possible.

  FIG. 3 is a sequence diagram of PFMIP in the system of FIG.

(S301) IP tunnel A is established between source MAG1A and LMA3. The mobile terminal 2 is connected to the source MAG 1A, and transmits / receives data packets to / from the destination server via the IP tunnel A and the LMA 3.
(S302) When the mobile terminal 2 performs a handover, the mobile terminal 2 transmits a movement notification including movement destination information for specifying a movement destination access network to the movement source MAG1A. Then, the mobile terminal 2 moves away from the source MAG 1A.
(S303) The source MAG1A transmits a handover start (Handover Initiate) message to the destination MAG1B. On the other hand, the destination MAG1B returns a handover confirmation (Handover ACK) message to the source MAG1A.
(S304) An IP tunnel B for data forwarding is established between the movement source MAG1A and the movement destination MAG1B.
(S305) Assume that the LMA 3 receives a data packet addressed to the mobile terminal 2. The LMA 3 transmits the data packet to the source MAG 1A via the IP tunnel A. The source MAG1A transmits the data packet to the destination MAG1B via the IP tunnel B. At this time, the mobile terminal 2 has not yet been connected to the destination MAG1B. Therefore, the destination MAG1B temporarily holds the data packet in the buffer.
(S306) Thereafter, the mobile terminal 2 connects to the destination MAG1B via the destination access network.
(S307) The destination MAG1B transmits the data packet temporarily stored in the buffer to the mobile terminal 2. Thereby, the data packet addressed to the mobile terminal 2 transmitted during the handover is received by the mobile terminal 2.
(S308) Then, the source MAG1A transmits a handover start message to the destination MAG1B. In response to this, the destination MAG1B returns a handover confirmation message to the source MAG1A.
(S309) Then, the source MAG 1A considers that the handover has ended, and disconnects the IP tunnels A and B.
(S310) Thereafter, the destination MAG1B newly establishes an IP tunnel A with the LMA. The mobile terminal 2 can connect to the destination MAG1B and send / receive data packets to / from the destination server via the IP tunnel A and the LMA3.

S. Gundavelli, "Proxy Mobile IPv6", IETF RFC5213, August 2008 H.Yokota, "Fast Handovers for Proxy MobileIPv6", IETF internet-draft, June 2009 Jeremy De Clercq, "Connecting IPv6 Islandsover IPv4 MPLS Using IPv6 Provider Edge Routers (6PE)", RFC 4798, February 2007 Andreas Polyrakis, Dimitrios Kalogeras, “NTUA Network Management Center 6PE: IPv6 over MPLS”, CISCO EXPO, January 2005, [online], [searched on December 9, 2009], Internet <URL: http: //www.netmode .ntua.gr / Presentations / 6PE% 20-% 20IPv6% 20over% 20MPLS% 20 (cisco% 20expo% 2005) .pdf> T.Bates, "Multiprotocol Extension for BGP-4", RFC4760, January2007

  According to the above-described prior art, there are two problems. The first problem is that, according to Proxy Mobile IPv6, all data packets transmitted and received by a mobile terminal must pass through an LMA. Therefore, a direct shortest path cannot be established for communication between terminals. Depending on the topology, the transfer delay may increase due to passing through the LMA.

  A second problem is that a loss of data packets addressed to the mobile terminal 2 may occur depending on the point of time when the data forwarding IP tunnel B in FIG. 3 is disconnected. According to FIG. 3, after exchanging the handover start message and the confirmation message in S309, the IP tunnels A and B are disconnected. However, at this time, packets already flowing in the IP tunnels A and B are lost along with the disconnection of the tunnel. Even if the source MAG 1A receives a data packet addressed to the mobile terminal 2 via the IP tunnel A, if the IP tunnel B has already been disconnected, the source MAG 1A discards the data packet. Become. This is because the source MAG1A does not recognize that the mobile terminal belongs to the access network under the destination MAG1B.

  Therefore, the present invention provides a handover method, system, access gateway, and program for a mobile terminal that can prevent loss of data packets addressed to the mobile terminal without passing through the LMA for handover in proxy mobile IPv6. The purpose is to provide.

According to the present invention, an IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and an access interconnected between the IP network and each access network In a mobile terminal handover method in a system having a gateway,
When the movement source access gateway of the first access network to which the mobile terminal is connected receives the movement start notification of the mobile terminal, the handover start message in the mobile terminal is transmitted to the movement destination access gateway of the movement destination access network A first step to:
A second step in which the source access gateway establishes an IP tunnel for data forwarding to the destination access gateway;
A third step in which the mobile terminal hands over from the source access gateway to the destination access gateway;
A fourth step in which the destination access gateway transmits an update message including the network prefix of the mobile terminal to the IP network in a broadcast manner;
When the source access gateway receives the update message via the IP network, the fifth step of holding the next hop gateway address for the network prefix of the mobile terminal as the address of the destination access gateway and disconnecting the IP tunnel It is characterized by having.

According to another embodiment of the handover method of the present invention,
The IP network is a proxy mobile IPv6 domain network configured by MP-BGP (Multiprotocol Extensions-Border Gateway Protocol),
The access gateway is 6PE (IPv6 Provider Edge Routers)
The update message is preferably a BGP-UPDATE message.

According to another embodiment of the handover method of the present invention,
The IP network is configured by MPLS (Multi Protocol Label Switching),
The IP network has a route reflector,
The IP tunnel is established by BGP / MPLS-VPN,
The BGP-UPDATE message is also preferably sent broadcast by a route reflector.

According to another embodiment of the handover method of the present invention,
For the fourth step,
When the mobile terminal is handed over, the source access gateway transfers the data packet to be transferred to the mobile terminal to the destination access gateway via the IP tunnel,
The destination access gateway buffers data packets received via the IP tunnel,
The destination access gateway preferably transmits the buffered data packet to the mobile terminal when the link connection from the mobile terminal is completed.

According to the present invention, an IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and an access interconnected between the IP network and each access network A mobile terminal handover system in which a mobile terminal performs handover from a source access gateway to a destination access gateway,
The source access gateway
Handover start means for transmitting a handover start message in the mobile terminal to the destination access gateway of the destination access network when receiving the movement start notification from the mobile terminal;
An update message receiving means for receiving an update message via an IP network;
Routing table recording means for holding the next hop gateway address for the network prefix of the mobile terminal as the address of the destination access gateway by the update message;
A tunnel control unit that establishes an IP tunnel for data forwarding to a destination access gateway when a handover start message is transmitted, and disconnects the IP tunnel when an update message is received;
The destination access gateway is
Tunnel control means for establishing an IP tunnel for data reception with the source access gateway;
Update message transmission means for transmitting an update message including the network prefix of the mobile terminal to the IP network when the connection from the mobile terminal is confirmed is provided.

According to another embodiment of the handover system of the present invention,
The IP network is a proxy mobile IPv6 domain network configured by MP-BGP,
The access gateway is 6PE,
The update message is preferably a BGP-UPDATE message.

According to another embodiment of the handover system of the present invention,
The IP network is composed of MPLS,
The IP network has a route reflector,
The IP tunnel is established by BGP / MPLS-VPN,
The BGP-UPDATE message is also preferably sent broadcast by a route reflector.

According to another embodiment of the handover system of the present invention,
When the mobile terminal is handed over, the source access gateway transfers the data packet to be transferred to the mobile terminal to the destination access gateway via the IP tunnel,
The destination access gateway buffers data packets received via the IP tunnel,
The destination access gateway preferably transmits the buffered data packet to the mobile terminal when the link connection from the mobile terminal is completed.

According to the present invention, an IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and the IP network and each access network are interconnected. In an access gateway that controls handover from a mobile terminal,
A handover start means for transmitting a handover start message in the mobile terminal to the access gateway of the access network serving as a destination when the movement start notification is received from the mobile terminal;
An update message receiving means for receiving an update message via an IP network;
Routing table recording means for holding the address of the access gateway included in the update message as the next hop gateway for the network prefix of the mobile terminal;
A tunnel control means for establishing an IP tunnel for data forwarding to a destination access gateway when a handover start message is transmitted, and disconnecting the IP tunnel when receiving an update message;
Update message transmission means for transmitting an update message including the network prefix of the mobile terminal to the IP network when the connection from the mobile terminal is confirmed is provided.

According to the present invention, an IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and the IP network and each access network are interconnected. In a program for functioning a computer mounted on an access gateway that controls handover from a mobile terminal,
A handover start means for transmitting a handover start message in the mobile terminal to the access gateway of the access network serving as a destination when the movement start notification is received from the mobile terminal;
An update message receiving means for receiving an update message via an IP network;
Routing table recording means for holding the address of the access gateway included in the update message as the next hop gateway for the network prefix of the mobile terminal;
A tunnel control unit that establishes an IP tunnel for data forwarding to the destination access gateway when a handover start message is transmitted and disconnects the IP tunnel for data forwarding when an update message is received; ,
When the connection from the mobile terminal is confirmed, the computer is caused to function as an update message transmission unit that broadcasts an update message including the network prefix of the mobile terminal to the IP network.

  According to the mobile terminal handover method, system, access gateway, and program of the present invention, it is possible to prevent loss of data packets addressed to the mobile terminal without passing through the LMA for the proxy mobile IPv6 handover. .

It is a system configuration | structure figure showing the handover of PMIP. It is a system configuration | structure figure showing the handover of PFMIP. FIG. 3 is a sequence diagram of PFMIP in the system of FIG. 2. It is a system configuration diagram in the present invention. It is a sequence diagram in the present invention. It is a function block diagram of the access gateway in this invention.

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

  FIG. 4 is a system configuration diagram according to the present invention.

  4, compared with FIG. 1, the proxy mobile IPv6 domain network 42 is configured by MP-BGP (Multiprotocol Extensions-Border Gateway Protocol) (see, for example, Non-Patent Document 5). Furthermore, it is also preferably configured as MP-BGP / MPLS (Multi Protocol Label Switching).

  BGP is one of EGP (Exterior Gateway Protocol), and is a protocol for setting a route by advertising route information to each other. According to BGP, the transport network 42 in FIG. 4 has the same AS (Autonomous System) number. The AS number is the only number assigned in the Internet world for each organization that is routed. According to FIG. 4, since a plurality of MAGs are between the same AS, they are configured by iBGP (internal BGP) peers. Route information is exchanged by exchanging route information by iBGP between MAGs constituting peers.

  According to BGP, AS authentication and address exchange are performed by exchanging OPEN messages to configure peers. Periodically confirm peer establishment by exchanging KEEPALIVE messages. Then, by exchanging UPDATE messages, a list of new route information of the route and route information to be deleted is transmitted and received.

  MPLS is a high-speed and large-capacity route control technology using a label switching method, and is mainly used on the Internet. According to this technique, a router recognizes a short fixed-length “label” instead of an IP header as identification information for controlling a route. The edge router provided at the entrance of the Internet attaches a label to the data packet received from the external network and transfers it to the Internet. The edge router provided at the exit of the Internet removes the label from the data packet and transfers it to the external network. By using the “label”, it is possible to separate the transfer processing and the route calculation processing, reduce the load on the router, and speed up the processing. In addition, advanced communication quality control (QoS) that is impossible with IP and construction of a private network (IP-VPN) are facilitated.

  A plurality of 6PE (IPv6 Provider Edge Routers) access gateways are connected to the transport network 42 configured by MP-BGP / MPLS (see, for example, Non-Patent Documents 3 and 4). The IP tunnel between the movement source 6PE and the movement destination 6PE is established by BGP / MPLS-VPN (Virtual Private Network). According to FIG. 4, an IP tunnel B for data forwarding is established between the movement destination MAG1B and the movement source MAG1A.

  Furthermore, according to FIG. 1, the transport network 43 is further provided with a route reflector 6. In the case of BGP, the number of speakers that transmit advertisements (advertize) increases, and the number of adjacent relationships (peers) becomes enormous in a full mesh structure, increasing the load on the router. Therefore, according to iBGP, by configuring peers only between the route reflector 6 and the MAG1, the number of peers is reduced and a routing loop is prevented.

  According to FIG. 4, the destination MAG1B transmits an update message (BGP-UPDATE) to the route reflector 6 when the data forwarding IP tunnel B is established with the source MAG1A. The BGP-UPADTE message transmitted by the 6PE includes the IP address of the destination MAG1B and the network prefix of the mobile terminal. The route reflector 6 broadcasts the BGP-UPDATE message received from the destination MAG1B.

  The source MAG1A that has received the BGP-UPDATE message holds the next hop gateway for the network prefix of the mobile terminal 2 as the IP address of the destination MAG1B. Then, the source MAG 1A disconnects the IP tunnel B for data forwarding.

  FIG. 5 is a sequence diagram in the present invention.

(S501) The mobile terminal 2 is connected to the source MAG 1A and transmits / receives data packets to / from a destination server connected to the Internet.
(S502) When handing over, the mobile terminal 2 transmits a movement notification including movement destination information for specifying a movement destination access network to the movement source MAG1A. Then, the mobile terminal 2 moves away from the source MAG 1A.
(S503) The source MAG1A transmits a handover start message to the destination MAG1B. In response to this, the destination MAG1B returns a handover confirmation message to the source MAG1A.
(S504) An IP tunnel for data forwarding is established between the movement source MAG1A and the movement destination MAG1B.
(S505) The data packet addressed to the mobile terminal 2 transmitted from the destination server is transmitted to the source MAG 1A. The source MAG1A transmits the data packet to the destination MAG1B via the IP tunnel B. At this time, the mobile terminal 2 has not yet been connected to the destination MAG1B. Therefore, the destination MAG1B temporarily holds the data packet in the buffer.
(S506) Thereafter, the mobile terminal 2 connects to the destination MAG1B via the destination access network.
(S507) The destination MAG1B transmits the data packet temporarily held in the buffer to the mobile terminal 2. Thereby, the data packet addressed to the mobile terminal 2 transmitted during the handover is received by the mobile terminal 2.
(S508) Next, the source MAG 1A transmits a BGP-UPDATE message to the route reflector 6. As a result, the BGP-UPDATE message is broadcast in the transport network 42 and is also received by the source MAG 1A.
(S509) Then, the source MAG 1A holds the next hop gateway for the network prefix of the mobile terminal 2 as the destination MAG 1B, and disconnects the IP tunnel B for data forwarding.
(S510) The mobile terminal 2 can connect to the destination MAG1B and transmit / receive data packets to / from the destination server.

  Thereafter, it is assumed that the source MAG 1A receives a data packet addressed to the mobile terminal 2. At this time, the IP tunnel B has already been disconnected, but the source MAG1A recognizes that the mobile terminal belongs to the access network under the destination MAG1B by the BGP-UPDATE message received in S508. ing. Therefore, the source MAG 1A can transmit the data packet to the mobile terminal under the destination MAG 1B.

  FIG. 6 is a functional configuration diagram of the access gateway in the present invention.

  According to FIG. 6, the access gateway 1 includes an IP interface unit 101 and an access network interface unit 102. The access gateway 1 includes a data transmission / reception unit 111, a tunnel control unit 112, a handover start unit 113, an update message reception unit 114, a routing table recording unit 115, and an update message transmission unit 116. These functional components are realized by executing a program that causes a computer mounted on the access gateway 1 to function.

  The IP interface unit 101 is connected to an Internet transport network, and transmits and receives IP packets to and from other MAGs.

  The access network interface unit 102 is connected to the access network and transmits / receives data packets to / from the mobile terminal.

  The data transmission / reception unit 111 transmits / receives data packets between a mobile terminal connected to the access network and another MAG. The route control of the data packet is based on the routing table recording unit 115. Further, when the mobile terminal 2 is not connected to the MAG, the data transmitting / receiving unit 111 temporarily buffers a data packet addressed to the mobile terminal 2 received via the IP tunnel. Then, when the mobile terminal 2 connects to the MAG, the buffered data packet is transmitted to the mobile terminal 2.

  When the handover start unit 113 transmits a handover start message, the tunnel control unit 112 establishes an IP tunnel for data forwarding with respect to the movement destination MAG1B. In addition, when the update message receiving unit 114 receives an update message from the destination MAG1B, the tunnel control unit 112 disconnects the data forwarding IP tunnel.

  When the handover start unit 113 receives a movement start notification from the mobile terminal 2, the handover start unit 113 transmits a handover start message in the mobile terminal 2 to the destination MAG1B of the destination access network.

  The update message receiving unit 114 receives the BGP-UPDATE message from the route reflector 6. Then, the network prefix of the mobile terminal and the IP address of the destination MAG1B are acquired from the BGP-UPDATE message. The bound information is output to the routing table recording unit 115.

  The routing table recording unit 115 binds and records the network prefix of the mobile terminal input from the update message receiving unit 114 and the IP address of the destination MAG1B. As a result, the IP address of the destination MAG1B is held as the next hop gateway for the network prefix of the mobile terminal.

  When the update message transmission unit 116 confirms the connection from the mobile terminal, the update message transmission unit 116 broadcasts a BGP-UPDATE message including the network prefix of the mobile terminal and the IP address of the destination MAG1B to the IP network. To do.

  As described above in detail, according to the handover method, system, access gateway, and program of the mobile terminal according to the present invention, the handover in proxy mobile IPv6 can be performed without going through the LMA and at the time of handover. Loss of the addressed data packet can be prevented.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

1 access gateway 1A source access gateway 1B destination access gateway 101 IP network interface unit 102 access network interface unit 111 data transmission / reception unit 112 tunnel control unit 113 handover start unit 114 update message reception unit 115 routing table recording unit 116 update message transmission unit 2 Mobile terminal 3 LMA
4 Internet 41 IPv6 Core Network 42 Transport Network 5 Access Network 5A Source Access Network 5B Target Access Network 6 Route Reflector

Claims (10)

A system having an IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and an access gateway interconnected between the IP network and each access network In the mobile terminal handover method in
A first step of transmitting a handover start message in the mobile terminal to the destination access gateway of the destination access network when the source access gateway of the source access network receives the movement start notification of the mobile terminal; ,
A second step in which the source access gateway establishes an IP tunnel for data forwarding to the destination access gateway;
A third step in which the mobile terminal is handed over from a source access gateway to a destination access gateway;
A fourth step in which the destination access gateway transmits an update message including the network prefix of the mobile terminal to the IP network in a broadcast manner;
When the source access gateway receives the update message via the IP network, it holds the next hop gateway address for the network prefix of the mobile terminal as the address of the destination access gateway and disconnects the IP tunnel A handover method comprising: a fifth step. The IP network is a proxy mobile IPv6 domain network configured by MP-BGP (Multiprotocol Extensions-Border Gateway Protocol),
The access gateway is 6PE (IPv6 Provider Edge Routers),
The handover method according to claim 1, wherein the update message is a BGP-UPDATE message. The IP network is configured by MPLS (Multi Protocol Label Switching),
The IP network comprises a route reflector;
The IP tunnel is established by BGP / MPLS-VPN,
The handover method according to claim 2, wherein the BGP-UPDATE message is broadcast by the route reflector. For the fourth step,
When the mobile terminal is handed over, the source access gateway transfers the data packet to be transferred to the mobile terminal to the destination access gateway via the IP tunnel,
The destination access gateway temporarily buffers the data packet received via the IP tunnel,
4. The destination access gateway transmits the buffered data packet to the mobile terminal when link connection from the mobile terminal is completed. 5. Handover method. An IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and an access gateway interconnected between the IP network and each access network In the mobile terminal handover system in which the mobile terminal performs handover from the source access gateway to the destination access gateway,
The source access gateway
Handover start means for transmitting a handover start message in the mobile terminal to the destination access gateway of the destination access network when receiving a movement start notification from the mobile terminal;
Update message receiving means for receiving an update message via the IP network;
Routing table recording means for holding a next hop gateway address for the network prefix of the mobile terminal as an address of a destination access gateway by the update message;
A tunnel control unit that establishes an IP tunnel for data forwarding to a destination access gateway when the handover start message is transmitted and disconnects the IP tunnel when the update message is received; And
The destination access gateway is
Tunnel control means for establishing an IP tunnel for data reception with the source access gateway;
A handover system comprising update message transmission means for broadcasting an update message including a network prefix possessed by the mobile terminal to the IP network when the connection from the mobile terminal is confirmed. . The IP network is a proxy mobile IPv6 domain network configured by MP-BGP,
The access gateway is 6PE,
The handover system according to claim 5, wherein the update message is a BGP-UPDATE message. The IP network is configured by MPLS,
The IP network comprises a route reflector;
The IP tunnel is established by BGP / MPLS-VPN,
The handover system according to claim 6, wherein the BGP-UPDATE message is broadcast by the route reflector. When the mobile terminal is handed over, the source access gateway transfers the data packet to be transferred to the mobile terminal to the destination access gateway via the IP tunnel,
The destination access gateway buffers the data packet received via the IP tunnel,
8. The destination access gateway transmits the buffered data packet to the mobile terminal when link connection from the mobile terminal is completed. Handover system. An IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and the IP network and each access network are interconnected, from the mobile terminal In the access gateway that controls the handover of
A handover start means for transmitting a handover start message in the mobile terminal to the access gateway of the access network that is a destination when the movement start notification is received from the mobile terminal;
Update message receiving means for receiving an update message via the IP network;
Routing table recording means for holding the address of the access gateway included in the update message as a next hop gateway for the network prefix of the mobile terminal;
A tunnel control unit that establishes an IP tunnel for data forwarding to a destination access gateway when the handover start message is transmitted, and disconnects the IP tunnel when the update message is received;
An access gateway, comprising: an update message transmission unit that broadcasts an update message including a network prefix possessed by the mobile terminal to the IP network when the connection from the mobile terminal is confirmed. . An IP network in which a route is set by advertising route information to each other, a plurality of access networks connected from a mobile terminal, and the IP network and each access network are interconnected, from the mobile terminal In a program for functioning a computer mounted on an access gateway that controls handover of
A handover start means for transmitting a handover start message in the mobile terminal to the access gateway of the access network that is a destination when the movement start notification is received from the mobile terminal;
Update message receiving means for receiving an update message via the IP network;
Routing table recording means for holding the address of the access gateway included in the update message as a next hop gateway for the network prefix of the mobile terminal;
A tunnel control unit that establishes an IP tunnel for data forwarding to a destination access gateway when the handover start message is transmitted, and disconnects the IP tunnel when the update message is received;
When the connection from the mobile terminal is confirmed, the computer is caused to function as an update message transmission unit that broadcasts an update message including a network prefix possessed by the mobile terminal to the IP network. Program for access gateway.

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