JP2006262352A - Mobile terminal, packet relay device, communication system, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile terminal, a packet relay device, a communication system, and a communication method which offer a seamless data communication in a network environment where IP protocols are mixed. <P>SOLUTION: A communication system 1 is provided with a mobile terminal having a move detection means 15a, a registration request means 15g, an IPv4 tunnel preparing means 15h, an IPv4IPv6 tunnel preparing means 15i, an IPv4 route control means 15e for controlling a route so as to perform a packet transfer through an IPv4 tunnel, and an IPv6 route control means 15f for controlling a route through an IPv4/IPv6 tunnel; and a packet relay device having an authentication means 25a, an IPv4 tunnel preparing means 25b, an IPv4IPv6 tunnel preparing means 25c, an IPv4 route control means 25f for controlling a route so as to perform a packet transfer with the mobile terminal through the IPv4 tunnel, and an IPv6 route control means 25g for controlling a route through the IPv4/IPv6 tunnel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile terminal, a packet relay device, a communication system, and a communication method that provide seamless data communication in a network environment in which protocols of different IP versions are mixed.

  In the IPv4 environment, mobile IPv4 technology is known for continuing communication with a server as a communication partner while changing a subnet while a terminal is moving. Similarly, in the IPv6 environment, there is a mobile IPv6 technology, and a seamless communication system is being developed to prevent communication from being interrupted in each environment. The basics of these mobile IP technologies are “movement detection”, “registration”, and “packet transfer”.

  Since IPv6 is expanded to 128 bits compared to the 32-bit IPv4 address space, it is highly expected as a countermeasure against IP address exhaustion. In the future, the number of terminals connected to the Internet is expected to increase, and implementation of IPv6 in mobile terminals such as mobile phones is being developed as an urgent matter. As a technique for achieving seamless communication continuation of mobile terminals, IETF defines RFC2002, RFC3220, etc. as mobile IPv4 protocols. Similarly, IPv3 specifies RFC3775, RFC3776, and the like. With these protocol technologies, even when moving in a network environment, it is possible to automatically set communication so that the user is not conscious, and data communication with a communication partner can be continued.

  In the future, while IPv6-compatible terminals are expected to become widespread, it is considered that there is still an IPv4 environment as an infrastructure, and seamless communication technology that does not interrupt communication between networks with different IP versions is required. . In a network system in which IPv6 and IPv4 environments are mixed, as a seamless communication technique when a mobile terminal moves from an IPv6 environment to an IPv4 environment, for example, a network relay device that is an IPv4 and IPv6 translator is installed in the communication system. A method of continuing seamless data communication in a communication system has been proposed (see Patent Document 1).

In addition, a method of switching a plurality of network interfaces by setting tunnel devices in advance has been proposed by the present applicant (see Patent Document 2).
JP 2003-18185 A JP 2003-169981 A

  However, in Patent Document 1, an IP protocol translator (network relay device) is installed to connect IPv6 and IPv4 environments, mobile IPv6 is activated, and seamless communication between different protocols is disclosed. A clear standard for seamless communication in an IPv6 mixed environment is not disclosed. In other words, since the installed home agent is compatible with Mobile IPv6, data continuity can be secured if the communication partner is the IPv6 server 401 when the mobile terminal moves to the IPv4 environment, but the mobile terminal can be secured by the IPv4 server 303. The processing when moving to a different IPv4 subnet environment during communication is not disclosed. Therefore, the home agent cannot activate the proxy ARP function.

  In addition, the translation by the header conversion method can be expected to increase the transfer speed, but if the IP address or port number of the communication destination is included in the data like FTP (File Translation Protocol), that portion In addition, there is a case where special processing is performed according to the upper layer protocol.

  Similarly in Patent Document 2, tunnel devices are set in the same IP environment in the network. However, a clear standard for seamless communication is not disclosed in a mixed environment of IPv4 and IPv6.

  In both Patent Documents 1 and 2, even if a mobile terminal or a home agent that implements both mobile IPv4 and mobile IPv6 is prepared, it is not possible to access an IPv6 environment server from a mobile terminal in an IPv4 environment under a mixed IP environment. Difficulty is expected.

  The present invention has been made in view of the above-described problems, and includes a mobile terminal and a packet relay device that are equipped with both IPv4 and IPv6 protocol stacks and provide seamless data communication in a network environment in which IP protocols are mixed. An object of the present invention is to provide a communication system and a communication method.

  In view of the above-mentioned problems, the first feature of the present invention is [a] movement for transmitting / receiving packets to / from the packet relay apparatus while moving between the first network and the second network which are networks in the IPv4 environment or the IPv6 environment. The terminal receives a signal output from an interface included in each network, and transmits a registration request to the movement detecting means 15a for detecting movement from the first network to the second network, and [b] the packet relay apparatus. Registration request means 15g, [c] IPv4 tunnel creation means 15h that receives a registration response to the registration request from the packet relay device and creates an IPv4 / IPv4 tunnel based on the registration response, and [d] registration request from the packet relay device Receives a registration response to and creates an IPv4 / IPv6 tunnel based on the registration response IPv4 IPv6 tunnel creation means 15i, and [e] IPv4 route control means 15e that performs route control so as to perform packet transfer with the packet relay device via the IPv4 / IPv4 tunnel if the second network of the movement destination is an IPv4 environment, [F] If the destination second network is an IPv6 environment, the mobile terminal is provided with IPv6 route control means 15f that performs route control so as to perform packet transfer with the packet relay device via the IPv4 / IPv6 tunnel. The gist.

  A second feature of the present invention is [a] a packet relay apparatus that performs packet transfer with a mobile terminal moving between a first network and a second network that are networks in an IPv4 environment or an IPv6 environment, and is registered from the mobile terminal. An authentication unit 25a that receives the request and authenticates the registration request and detects that the mobile terminal has moved from the first network to the second network; and [b] if authentication is performed normally, a registration response to the registration request IPv4 tunnel creating means 25b for creating an IPv4 / IPv4 tunnel based on the registration request, and [c] If authentication is performed normally, a registration response to the registration request is sent to the mobile terminal. IPv4 / IPv6 tunnel creating means 25c for creating an IPv4 / IPv6 tunnel based on the network, and [d] the second network If it is a Pv4 environment, IPv4 route control means 25f that performs route control so that packet transfer with the mobile terminal is performed via an IPv4 / IPv4 tunnel, and [e] If the second network is an IPv6 environment, packets with the mobile terminal The gist of the present invention is that the packet relay apparatus includes an IPv6 route control unit 25g that performs route control so that forwarding is performed via an IPv4 / IPv6 tunnel.

  The third feature of the present invention is [a] a communication system including a mobile terminal that moves between a first network and a second network that are networks in an IPv4 environment or an IPv6 environment, and a packet relay device that transmits and receives packets to and from the mobile terminal. A movement detecting unit 15a for receiving a signal output from an interface included in each network and detecting movement from the first network to the second network; a registration requesting unit 15g for transmitting a registration request to the packet relay device; An IPv4 tunnel creating means 15h that receives a registration response to the registration request from the packet relay device and creates an IPv4 / IPv4 tunnel based on the registration response, receives a registration response to the registration request from the packet relay device, and IPv4 based on the registration response / IPv4 IPv6 to create IPv6 tunnel If the second network of the movement destination is an IPv4 environment, the IPv4 route control means 15e for controlling the route so that the packet transfer with the packet relay device is performed via the IPv4 / IPv4 tunnel, and the second of the movement destination If the network is in an IPv6 environment, mobile terminals each having IPv6 route control means 15f that performs route control to perform packet transfer with the packet relay device via the IPv4 / IPv6 tunnel, and [b] receive a registration request from the mobile terminal Authentication means 25a for authenticating the registration request and detecting that the mobile terminal has moved from the first network to the second network, and IPv4 for creating an IPv4 / IPv4 tunnel based on the registration request if the authentication is successful. When the tunnel creation means 25b is successfully authenticated, it is based on the registration request. IPv4 IPv6 tunnel creating means 25c for creating a Pv4 / IPv6 tunnel, and, if the second network is an IPv4 environment, IPv4 route control means 25f for controlling the route so that packet transfer with the mobile terminal is performed via the IPv4 / IPv4 tunnel, and 2 If the network is an IPv6 environment, the gist of the invention is that the communication system includes packet relay apparatuses each having IPv6 route control means 25g for performing route control so as to perform packet transfer with a mobile terminal via an IPv4 / IPv6 tunnel. To do.

  A fourth feature of the present invention is [a] a mobile terminal that moves between a first network and a second network, which are networks in an IPv4 environment or an IPv6 environment, and transmits / receives a packet to / from the packet relay apparatus, in each network. A movement detection step for receiving a signal output from the interface and detecting movement from the first network to the second network; [b] the mobile terminal transmits a registration request to the packet relay apparatus; An authentication step for authenticating the received registration request, [c] a mobile terminal receiving a registration response to the registration request from the packet relay device, and creating an IPv4 / IPv4 tunnel based on the registration response; [d] the mobile terminal Receives a registration response to the registration request from the packet relay device, and based on the registration response, IPv4 / A step of creating a Pv6 tunnel; and [e] a path control for performing packet transfer with the packet relay device via the IPv4 / IPv4 tunnel if the second network to which the mobile terminal is moved is an IPv4 environment; [F] If the second network to which the mobile terminal is moving is an IPv6 environment, the step of routing the packet transfer with the packet relay device via the IPv4 / IPv6 tunnel, and [G] authentication is performed normally. The packet relay device creates an IPv4 / IPv4 tunnel based on the registration request, and [h] if the authentication is normally performed, the packet relay device creates an IPv4 / IPv6 tunnel based on the registration request. [Ri] If the second network is an IPv4 environment, the packet relay device A route control to perform packet forwarding via an IPv4 / IPv4 tunnel, and [nu] If the second network is in an IPv6 environment, the packet relay device performs packet forwarding with the mobile terminal via the IPv4 / IPv6 tunnel. The gist of the present invention is a communication method including a step of performing path control.

  According to the mobile terminal, packet relay apparatus, communication system, and communication method of the present invention, data continuity can be ensured even if the mobile terminal moves to a protocol environment of a different IP version. When the mobile terminal moves from the IPv6 environment into the IPv4 environment, data communication can be performed without depending on whether the communication partner of the mobile terminal is the IPv4 or IPv6 environment.

  Hereinafter, a communication apparatus according to an embodiment of the present invention will be described. In addition, the apparatus, method, etc. which are used in embodiment of this invention are examples, and of course, this invention is not limited to these.

(Communications system)
The communication system 1 according to the embodiment of the present invention includes an IPv4 network 300 and an IPv6 network 400, as shown in FIG. The IPv4 network 300 and the IPv6 network 400 are connected by the packet relay apparatus 200, and the mobile terminal 100 can freely move between the IPv4 network 300 and the IPv6 network 400.

  The IPv4 network 300 is divided into a first subnet 330 and a second subnet 331 by installing the first router 301 and the second router 302. The first subnet 330 includes a DHCP (Dynamic Host Configuration Protocol) server 310 and an access point 320. The second subnet 331 includes a DHCP server 311 and an access point 321.

  The mobile terminal 100 has a fixed home address defined by mobile IP. Two home addresses for IPv4 and IPv6 environments are prepared and set with the packet relay apparatus 200 in advance.

  For example, in FIG. 1, the mobile terminal 100 includes “192.168.0.22” for IPv4 and “2002: c0a8: e6 :: c0a8: 16” for IPv6 as home addresses. The other addresses will be described. The IP addresses of the first router are “192.168.10.254” and “192.168.20.254”. The IP addresses of the second router are “192.168.20.230” and “192.168.30.254”. The IPv4 address of the packet relay apparatus 200 is “192.168.10.230”, and the IPv6 address is “2002: c0a8: e6 :: c0a8: e6”. The address of the IPv4 server 303 is “192.168.30.1”. The address of the IPv6 server 401 is “3ffe: 0: c: ffff :: abcd”.

(Each system device)
Next, each device of the communication system 1 will be described in detail. The first router 301 and the second router 302 are devices that recognize a destination IP address and relay a packet, and are used to divide subnets in an IPv4 environment.

  The DHCP servers 310 and 311 are set with an IP address such as a gateway server, a subnet mask, a range of IP addresses that can be assigned to clients, and provide such information to a terminal computer that has accessed. When the terminal finishes communication, the address is automatically collected and assigned to another computer. The DHCP servers 310 and 311 are installed in the first subnet and the second subnet, respectively, and respond with an IPv4 address used in each subnet, that is, a care-of address (COA), in response to a request from the mobile terminal 100.

  The access points 320 and 321 output a beacon signal in a frequency band defined by, for example, IEEE 802.11 / a / b / g, and perform data communication with the mobile terminal 100 by radio waves. As an alternative to the access points 320 and 321, a wired hub may be installed so that the mobile terminal 100 can be wired. In this case, the mobile terminal 100 is equipped with a wired communication interface.

  The IPv4 server 303 is arranged in the IPv4 network 300 and executes applications such as MAIL, FTP, HTTP, NFS, and TELNET. It is assumed that the position of the IPv4 server 303 is not fixed and only needs to exist in the IPv4 network 300.

  Further, the number of routers and the number of subnets in the IPv4 network 300 may be increased or decreased, and the connection configuration may be changed.

(Mobile terminal)
The mobile terminal 100 is a notebook personal computer, PDA, mobile phone, or the like that supports both IPv4 and IPv6 environments. As shown in FIG. 2, the mobile terminal 100 includes an input device 11, an output device 12, a communication control device 13, a communication interface 14, a central processing control device (CPU) 15, a main storage device 16, a route table storage device 17, and the like. I have.

  The input device 11 is an interface that receives an input signal from a keyboard, a mouse, or the like. The output device 12 is an interface for transmitting output signals such as processing results. A liquid crystal display, a CRT display, a printer, etc. may be included. The communication control device 13 generates a control signal for transmitting / receiving data to / from another device. The communication interface 14 is a device for transmitting and receiving data between other devices, and is equipped with one or more interfaces such as radio wave, optical radio, or cable. The main storage device 16 temporarily stores a program describing a processing procedure and data to be processed as a main memory, and delivers a machine instruction and data of the program according to a request from the CPU 15. Data processed by the CPU 15 is written to the main storage device 16. The main storage device 16 and the CPU 15 are connected by an address bus, a data bus, a control signal, and the like.

  The routing table storage device 17 includes an IPv4 routing table and an IPv6 routing table created on the mobile terminal 100 side as shown in FIG. 3, an updated IPv4 routing table as shown in FIG. Stores the settings of the tunnel device created on the mobile terminal 100 side.

  The CPU 15 includes movement detection means 15a, care-of-address acquisition means 15b, IPv4 route table creation means 15c, IPv6 route table creation means 15d, IPv4 route control means 15e, IPv6 route control means 15f, registration request means 15g, IPv4 tunnel creation means. 15h, IPv4IPv6 tunnel creating means 15i and the like.

  The movement detection means 15a is a means for detecting whether or not the movement detection means 15a has moved beyond the subnet boundary. The care-of-address acquisition unit 15 b is a unit that acquires an IP address and default gateway information from the DHCP server 311.

  The IPv4 route table creation means 15c creates an IPv4 route table as shown in FIGS. 3A and 3B when the mobile terminal 100 is activated or after movement is detected. The IPv4 route table in FIG. 3 shows an example in which the mobile terminal 100 is activated in the second subnet 331 and the route table is created. Details regarding FIG. 3 will be described later.

  The IPv6 route table creating means 15d creates an IPv6 route table as shown in FIG. 3C when the mobile terminal 100 is activated or after movement is detected. In the IPv6 route table, as indicated by numbers 2 and 3 in the figure, the interface is assigned to a physical device named Eth0. In other words, the interface is not a tunnel device at this stage.

  The IPv4 route control means 15e is a means for controlling the IPv4 route table. For example, the packet is transferred to the packet relay apparatus 200 using the tunnel created by the IPv4 tunnel creation means 15h. The IPv6 route control means 15f is a means for controlling the IPv6 route table. The packet is transferred to the packet relay apparatus 200 using the tunnel created by the IPv4 IPv6 tunnel creation means 15i. The registration request unit 15g issues a registration request to the packet relay apparatus 200.

  The IPv4 tunnel creation means 15h creates an IPv4 / IPv4 tunnel that is a tunnel device that operates as a virtual communication interface. The IPv4 IPv6 tunnel creation means 15i creates an IPv4 / IPv6 tunnel which is a tunnel device that operates as a virtual communication interface.

(Packet relay device)
The packet relay apparatus 200 is equipped with an IPv4 router function and an IPv6 router function in order to connect the IPv4 network 300 and the IPv6 network 400. In the example of FIG. 1, the IPv6 server 401 functions as a default router.

  As shown in FIG. 6, the packet relay device 200 includes an input device 21, an output device 22, a communication control device 23, a communication interface 24, a CPU 25, a main storage device 26, a route table storage device 27, and the like.

  The routing table storage device 27 includes an IPv4 routing table and an IPv6 routing table as shown in FIG. 8 created on the packet relay device 200 side, and a tunnel device created on the packet relay device 200 side as shown in FIG. Stores settings etc.

  The CPU 25 includes an authentication unit 25a, an IPv4 tunnel creation unit 25b, an IPv4 IPv6 tunnel creation unit 25c, an IPv4 route creation unit 25d, an IPv6 route creation unit 25e, an IPv4 route control unit 25f, an IPv4 IPv6 route control unit 25g, and the like.

  In response to the registration request from the mobile terminal 100, the authentication unit 25a performs an authentication process using a method or the like prescribed in Mobile IPv4. The IPv4 tunnel creation means 25b creates an IPv4 / IPv4 tunnel as shown in FIG. The IPv4 / IPv6 tunnel creating means 25c creates an IPv4 / IPv6 tunnel as shown in FIG. 7 (b).

  The IPv4 route table creation unit 25d creates an IPv4 route table as shown in FIG. 8A when the packet relay apparatus 200 is activated in the environment as shown in FIG. In FIG. 8A, a packet corresponding to 192.168.10.0/24 in the number 1 is routed using the interface Eth0. The numbers 2 and 3 do not particularly define details because they vary depending on the number of interfaces attached to the packet relay apparatus and the subnet configuration for each interface. No. 4 shows an example in which the default router is designated as the address 301 in FIG.

  The IPv6 route table creating unit 25e creates an IPv6 route table as shown in FIG. 8B when the packet relay apparatus 200 is activated in the environment as shown in FIG. In FIG. 8B, number 1 indicates an own loopback route, and number 2 indicates an example clearly indicating that a packet can be transferred to the IPv6 server 401.

  The IPv4 route control means 25f controls the IPv4 route. For example, the IPv4 route is corrected as shown in FIG. The IPv4 IPv6 route control means 25g controls the IPv6 route. For example, the IPv6 route is corrected as shown in FIG.

  Other devices are the same as those of the mobile terminal 100 shown in FIG.

(Communication method)
The overall operation of the communication system 1 is shown in the sequence diagram of FIG. The solid line in FIG. 9 indicates the operation of the mobile terminal 100 before movement, and the dotted line indicates the operation of the mobile terminal 100a after movement. When the mobile terminal 100 is activated, the IPv4 route table creation unit 15c creates the IPv4 route table shown in FIGS. 3A and 3B in advance, and the IPv6 route table creation unit 15d uses the IPv6 route shown in FIG. 3C. A routing table shall be created. Also, when the packet relay apparatus 200 is activated, the IPv4 route table creation means 25d creates the IPv4 route table in FIG. 8A in advance, and the IPv6 route table creation means 25e obtains the IPv6 route table in FIG. 8B. Shall be created.

(A) First, it is assumed that the mobile terminal 100 before moving exists in the first subnet 330 of FIG. At this time, a care-of address is acquired from the DHCP server 310 in step S1. At this time, the mobile terminal 100 corrects the IPv4 route table.

(B) In step S2, based on the care-of address, the packet relay apparatus 200 is requested to register, and in step S3, the registration response is received. When registration is performed normally, the packet relay apparatus 200 corrects the IPv4 route table and the IPv6 route table.

(C) In step S4, the mobile terminal 100 creates an IPv4 / IPv4 tunnel, and after creation, the IPv4 data is transmitted between the mobile terminal 100 and the packet relay apparatus 200 via the IPv4 / IPv4 tunnel with the IPv4 server 303. (Step S5) or receive (step S6). Similarly, in step S7, the mobile terminal 100 creates an IPv4 / IPv6 tunnel, and after creation, the mobile terminal 100 and the packet relay apparatus 200 transmit IPv6 data with the IPv6 server 401 via the IPv4 / IPv6 tunnel. (Step S8) or receive (Step S9).

(D) Next, it is assumed that the mobile terminal 100 has moved to the second subnet 331. The mobile terminal 100a after moving acquires a care-of address from the DHCP server 311 in step S10. In step S11, the packet relay apparatus 200 is requested to register again, and the registration response is received in step S12. In addition, the mobile terminal 100a and the packet relay apparatus 200 update their route tables.

(E) In step S13, the mobile terminal 100a updates the IPv4 / IPv4 tunnel, and after the update, transmits and receives IPv4 data to and from the IPv4 server 303 via the updated IPv4 / IPv4 tunnel, as in steps S5 and S6. . Similarly, in step S14, the mobile terminal 100 updates the IPv4 / IPv6 tunnel. After the update, the mobile terminal 100 transmits / receives IPv6 data to / from the IPv6 server 401 via the updated IPv4 / IPv6 tunnel as in steps S8 and S9.

  As an example of actually performing data communication in the above-described operation, the mobile terminal 100 in FIG. 1 transmits ICMP (Internet) to the IPv4 server 303 and the IPv6 server 401 from the destination subnet “192.168.20.0/24”. The relationship between the structure of the packet header and the data flow when the Ping command is transmitted / received by the control message protocol) will be described with reference to FIG.

  First, in step S21, the mobile terminal 100 acquires a care-of address “192.168.20.100”. A Ping request from the mobile terminal 100 to the IPv4 server 303 is transmitted to the packet relay apparatus 200 as an address “192.168.10.230” addressed to the packet relay apparatus 200 by the IPv4 / IPv4 tunnel device. In step S 22, the packet relay apparatus 200 extracts the data part from the IPv4 / IPv4 tunnel, and transfers the packet to the address “192.168.30.1” of the IPv4 server 303.

  In step S23, when a Ping reply is transmitted from the IPv4 server 303, the tunnel device of the packet relay apparatus 200 transmits to the care-of address of the mobile terminal 100 in step S24.

  In the case of a Ping request to the IPv6 server 401, the packet data from the mobile terminal is transmitted to the IPv4 address “192.168.10.230” of the packet relay apparatus 200 via the IPv6 / IPv4 tunnel in step S25. The In the data, the IPv6 address “2002: c0a8: e6 :: c0a8: 16” of the mobile terminal 100 is set as the transmission source, and the IPv6 server 401 address “3ffe: 0: c: ffff :: abcd” is set as the transmission destination. In step S <b> 26, the packet relay apparatus 200 extracts an IPv6 Ping request from the IPv6 / IPv4 tunnel and transfers it to the corresponding IPv6 server 401.

  In step S27, the IPv6 server 401 returns a Ping reply to the packet relay apparatus 200 which is a default router. In step S28, the packet relay apparatus 200 transmits a Ping reply to the care-of address of the mobile terminal 100 through the IPv4 / IPv6 tunnel.

(Protocol stack)
Next, a protocol stack used in the communication system 1 in FIG. 1 will be described. As an example, the mobile terminal 100 in FIG. 1 is provided with a radio wave radio interface and an optical radio interface. The subnet 331 is an in-house office room or the like and includes an optical wireless access point 322, and the subnet 330 is an in-house laboratory or the like and includes a radio wave access point 320.

  When the mobile terminal 100 moves to the subnet 331, data communication is performed with the IPv4 server 303 and the IPv6 server 401 via the optical wireless interface. Further, when the mobile terminal 100 moves to the subnet 330, the optical wireless interface is switched to the radio wave wireless interface to perform data communication with both servers. In this way, the mobile terminal 100 ensures data continuity with both servers by switching interfaces when moving in an IP environment.

  As an example of the application in the communication system 1, when a ping application is executed, the flow of data communication between the IPv4 server 303 and the mobile terminal 100 is as shown in FIG.

(A) First, in step S31, the IPv4 server 303 is requested to ping. The communication service layer transmits a ping request to the TCP / UDP layer. In step S32, the TCP / UDP layer UDP is used to add a header or the like to the ping request packet by the IPv4 layer. Since the ping request is a packet addressed to the IPv4 address, an IPv4 header is added.

(B) In step S33, the IPv4 route table is referred to, and communication is set to the IPv4 server 303 via the tunnel device. In step S34, the packet flows to the tunnel device “tunl1”. In tun1, the destination address is encapsulated in the packet relay device 200.

(C) In step S35, the ping request packet addressed to the packet relay apparatus 200 refers to the IPv4 route table again. As a result of referring to the IPv4 route table, for example, if it is set to be transmitted by the communication device Eth0 that is an optical wireless interface, the corresponding packet is transmitted to the optical wireless interface layer in step S36. In step S37, the packet is delivered to the destination LAN or access point.

  Similarly, the flow of data communication between the IPv6 server 401 and the mobile terminal 100 when the ping application is executed in the IPv6 server 401 and the mobile terminal 100 is as shown in FIG.

(A) First, in step S41, the IPv6 server 401 is requested to ping. The communication service layer transmits a ping request to the TCP / UDP layer. In step S42, a header such as an IPv6 header is added to the ping request command addressed to the IPv6 server 401 by the IPv6 layer.

(B) In step S43, the IPv6 route table is referenced. Since the packet is addressed to the IPv6 server 401 as a result of the reference, the packet is set to be transferred to the IPv6 / IPv4 tunnel device. In step S44, the packet is transferred to the tunnel device sit1. The tunnel device sit1 encapsulates the destination address into the packet relay device 200 (IPv4 address).

(C) In step S45, since the encapsulated data packet is an IPv4 packet, the IPv4 route table is referred to. As a result of referring to the IPv4 route table, for example, if it is set to be transmitted by the communication device Eth0 that is an optical wireless interface, the corresponding packet is transmitted to the optical wireless interface layer in step S46. In step S47, the packet is delivered to the destination LAN or access point.

  As described above, when the packet is transferred from the IPv6 environment to the IPv4 environment, the packet is routed through the IPv4 / IPv6 route table.

(Mobile terminal operation)
Next, a communication operation when the mobile terminal 100 moves from the first subnet 330 to the second subnet 331 will be described in detail with reference to the flowchart of FIG. It should be noted that an IPv4 route table as shown in FIGS. 3 (a) and 3 (b) and an IPv6 route table as shown in FIG. 3 (c) are created either when the mobile terminal 100 is activated or detected at step S101. It shall be.

(A) First, in step S101, the movement detection means 15a of the mobile terminal 100 in FIG. 2 detects whether or not it has moved beyond the subnet boundary. As a movement detection method, for example, a method of detecting that a router advertisement packet has been received and moving to a different subnet, or a signal intensity of a radio access point is observed, and a new access point above a threshold level is observed. There is a method to judge that it has moved. If a communication interface other than radio waves is used, a link signal such as a wired signal or optical radio is observed, and it may be determined that the link signal has moved when the link signal changes from OFF to ON. At this time, the movement processing operation is performed. This operation will be described later.

(B) If movement is detected, the care-of-address acquisition unit 15b acquires the IP address and default gateway information from the DHCP server 311 in step S102. This IP address is used as a care-of address in the second subnet 331 of the movement destination. The default gateway information sets the default gateway of the second subnet 331 as the address “192.168.20.254” of the first router 301.

  (C) In step S103, the IPv4 route table creation means 15c creates an IPv4 route table as shown in FIG. When the packet is transmitted and forwarded, this route table is referred to, and the packet is transmitted and forwarded to the communication partner on the basis of the interface and setting value matched in the table. For example, in FIG. 3A, the IPv4 route is set by a method that does not directly route the route addressed to the packet relay device. In the number 1, the packet addressed to 192.168.20.0/24, that is, the packet addressed to the second subnet 331 is set to transfer the packet using the interface Eth0. Number 2 is a notation for a loopback test, that is, a route inside the terminal itself.

  The number 3 is set so that all packets that do not match the numbers 1 and 2 are transmitted to the gateway “192.168.20.254”, that is, the first router 301 via the interface Eth0. That is, the IPv4 route table of FIG. 3A designates the first router 301 with the number 3 in order to transmit a packet addressed to the packet relay apparatus 200 “192.168.10.230”. The first router 301 routes the packet to the packet relay apparatus 200 by a tunnel device described later.

  On the other hand, FIG. 3B is an IPv4 route table in which a route to the packet relay apparatus 200 is directly added to FIG. As a result, the packet addressed to the packet relay apparatus 200 is transferred to the first router 301 set as default via the interface Eth0.

  Packets destined for the packet relay apparatus 200 can be reliably transmitted in either of the IPv4 route tables of FIGS. 3 (a) and 3 (b). However, in the tunnel device described later, if the route control is performed in the route table of FIG. 3B, the route control can be performed only by changing the route setting of the number 4 in the route table of FIG. Efficiency is good.

(D) In step S <b> 104, the registration request unit 15 g in FIG. 2 issues a registration request to the packet relay device 200. The registration request packet is a registration request packet defined in Mobile IPv4, and is transmitted including the IPv6 home address “2002: c0a8: e6 :: c0a8: 16” of the mobile terminal 100 shown in FIG. When the IPv6 home address is not included, the packet relay apparatus 200 holds a table for converting the IPv4 home address “192.168.0.22” of the mobile terminal 100 to the IPv6 home address, and the like by referring to this table. The IPv6 home address of the mobile terminal 100 is acquired. In addition to management using such a table, the IPv6 home address may be managed by a method determined in advance between the packet relay apparatus 200 and the mobile terminal 100. For example, “2002: Home IPv4 subnet :: Fixed IPv4 home address” is set.

  The packet relay apparatus 200 manages the IPv4 and IPv6 home addresses of the mobile terminal 100, and is used to authenticate and determine the mobile terminal 100 to be managed.

  If the packet relay apparatus 200 does not accept a registration request because of a timeout or an unmanaged mobile terminal, this process ends.

(E) When the registration request is accepted, the IPv4 tunnel creation means 15h creates an IPv4 / IPv4 tunnel in step S105. The IPv4 / IPv6 tunnel creating means 15i creates an IPv4 / IPv6 tunnel. Both tunnels are tunnel devices that operate as virtual communication interfaces. If a tunnel device has been created before, the tunnel is updated by modifying the source address.

  For example, it is assumed that the care-of address “192.168.20.100” is obtained from the destination DHCP server 311. In this case, the name of the IPv4 / IPv4 tunnel is assumed to be “tunl1”, the IP address of the tunnel device is the IPv4 home address of the mobile terminal 100, the source address is the care-of address, and the destination address is the IP address of the packet relay device 200. Designate and create tun1 as shown in FIG. Tunl1 conforms to RFCin IPinIP.

  Similarly, the name of the IPv4 / IPv6 tunnel is “sit1”, the IP address of the tunnel device is the IPv6 home address of the mobile terminal 100, the source address is the care-of address, and the destination address is the IP address of the packet relay device 200. Designate and create site1 as shown in FIG.

(F) In step S106, route control is performed based on the created IPv4 and IPv6 route tables.

  The IPv4 route control means 15e sets the default gateway address to the IP address of the packet relay device 200 as shown in the number 4 of the IPv4 route table in FIG. 5A, and the IPv4 tunnel creation means 15h sets the interface to be used. Set to created tunl1. As a result, data packets other than those destined for the destination second subnet 331 use tun1.

  Similarly, the IPv6 route control means 15f uses the site 1 created by the IPv4 IPv6 tunnel creation means 15i for destination packets that do not match the numbers 1 and 2, as shown in the number 3 of the IPv6 route table in FIG. 5B. Set to If the route that matches the upper bits of the IPv4 / IPv6 tunnel device, such as number 2, here "2000" is also set to use site1, the IPv6 address that matches this will use site1. Thus, the transfer between the packet relay devices 200 can be made more reliable. Number 2 changes the Destination (destination) depending on how the IPv6 address of the tunnel device is assigned.

(Operation of packet relay device)
Next, the communication operation of the packet relay apparatus 200 will be described in detail with reference to the flowchart of FIG. It should be noted that an IPv4 route table as shown in FIG. 8 (a) and an IPv6 route table as shown in FIG. 8 (b) are created either when the packet relay device 200 is activated or when detected in step S201. To do.

(A) In step S201, the authentication unit 25a of the packet relay apparatus 200 in FIG. 6 receives a registration request from the mobile terminal 100 and performs an authentication process. The authentication method is performed by a method specified in Mobile IPv4. Alternatively, the home address of the mobile terminal 100 included in the registration request is compared to determine whether the mobile terminal 100 is a management target. The home address to be compared may be either IPv4 or IPv6, but if the IPv6 home address is not included in the registration request from the mobile terminal 100 as described above in step S101, refer to the conversion table held in advance, An IPv6 home address is obtained from the IPv4 home address. As a result of the determination, if the mobile terminal 100 is not a management target, an authentication failure is returned to the mobile terminal 100 in step S202, and this process ends. If the authentication is successful, authentication success is returned to the mobile terminal 100 in step S203, and the process proceeds to step S204.

  (B) In step S204, the IPv4 tunnel creation means 25b creates an IPv4 / IPv4 tunnel. As shown in FIG. 7A, the name of the IPv4 / IPv4 tunnel is assumed to be “Tunl1” and the home address is set to the IPv4 address “192.168.10.230” of the packet relay apparatus 200, as in the mobile terminal 100. The transmission source address is set to the address of the packet relay apparatus 200, and the transmission destination address is set to the care-of address of the mobile terminal 100.

  Similarly, the IPv4 / IPv6 tunnel creating means 25c creates an IPv4 / IPv6 tunnel. As shown in FIG. 7B, the name of the IPv4 / IPv6 tunnel is assumed to be “sit1” and the home address is the IPv6 address “2002: c0a8: e6 :: c0a8:” of the packet relay apparatus 200, as in the mobile terminal 100. In “e6”, the source address is set to the IPv4 address of the packet relay apparatus 200, and the destination address is set to the care-of address of the mobile terminal 100.

(C) In step S205, the IPv4 route control means 25f modifies the IPv4 route table as shown in FIG. 8C for route control. That is, as indicated by the number 1, the packet addressed to the home address of the mobile terminal 100 is set to use Tunl1.

  Further, the IPv4 IPv6 route control means 25g adds the route of the IPv6 address created by the mobile terminal 100 at the destination to the IPv6 route table, and corrects the IPv6 route table as shown in FIG. That is, as indicated by the number 2, the packet addressed to the IPv6 home address of the mobile terminal 100 is set to use site 1.

(Move processing operation)
Next, the movement processing operation after detecting that the mobile terminal 100 has moved in the subnet in step S101 will be described with reference to the sequence diagram of FIG.

(a) First, in step S301, when the mobile terminal 100 detects movement, the DHCP client is activated to obtain network settings such as a care-of address and an IP address of a default router. Specifically, a DHCP discover packet is transmitted in order to discover the DHCP server 311 in the second subnet 331 at the movement destination.

(B) In step S302, the DHCP server 311 returns a usable network setting as a DHCP offer packet. In step S303, the mobile terminal 100 requests a network setting to be used by a DHCP request packet. In step S304, when permitting the request, the DHCP server 311 replies to that effect with a DHCP acknowledge packet.

(C) The mobile terminal 100 that has obtained the network setting in the second subnet 331 of the movement destination from the DHCP server 311 transmits a registration request to the packet relay apparatus 200 as described in step S102 of FIG. 13 (S305). The packet relay apparatus 200 transmits a packet with a registration response to the destination care-of address after authentication (S306).

  As described above, even when a mobile terminal moves from an IPv4 environment or a subnet of an IPv6 environment to another IPv4 environment subnet in a heterogeneous IP version mixed network environment in the transition period from IPv4 to IPv6, By setting, it is possible to automatically correspond to the network environment of the movement destination. As a result, a communication service that ensures continuity of data communication can be provided.

It is a figure which shows the structure of the communication system which concerns on embodiment of this invention. It is a figure which shows the structure of the mobile terminal which concerns on embodiment of this invention. It is a figure which shows the data structure of the IPv4 routing table by the side of a mobile terminal. It is a figure which shows the data structure of the tunnel device by the side of a mobile terminal. It is a figure which shows the data structure after correction | amendment of the routing table by the side of a mobile terminal. It is a figure which shows the structure of the packet relay apparatus which concerns on embodiment of this invention. It is a figure which shows the data structure of the tunnel device by the side of a packet relay apparatus. It is a figure which shows the data structure after correction | amendment of the routing table by the side of a packet relay apparatus. It is a sequence diagram which shows the whole operation | movement of a communication system. It is a sequence diagram which shows the packet flow operation | movement of a communication system. It is a flowchart which shows the packet flow operation | movement along a protocol stack. It is a flowchart which shows the packet flow operation | movement along a protocol stack. It is a flowchart which shows operation | movement of a mobile terminal. It is a flowchart which shows operation | movement of a packet relay apparatus. It is a flowchart which shows the operation | movement of the movement process of a mobile terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Communication system 11 ... Input device 12 ... Output device 13 ... Communication control device 14 ... Communication interface 15 ... CPU
15a ... movement detection means 15b ... care of address acquisition means 15c ... IPv4 route table creation means 15d ... IPv6 route table creation means 15e ... IPv4 route control means 15f ... IPv6 route control means 15g ... registration request means 15h ... IPv4 tunnel creation means 15i ... IPv4 IPv6 tunnel creation means 16 ... Main storage device 17 ... Routing table storage device 21 ... Input device 22 ... Output device 23 ... Communication control device 24 ... Communication interface 25 ... CPU
25a ... Authentication means 25b ... IPv4 tunnel creation means 25c ... IPv4 IPv6 tunnel creation means 25d ... IPv4 route creation means 25e ... IPv6 route creation means 25f ... IPv4 route control means 25g ... IPv6 route control means 26 ... Main storage device 27 ... Path table storage Device 100, 100a ... Mobile terminal 200 ... Packet relay device 200 ... Mobile terminal 300 ... IPv4 network 301 ... First router 302 ... Second router 303 ... IPv4 server 310, 311 ... DHCP server 320 ... Access point 320, 321 ... Access point 330 ... 1st subnet 331 ... 2nd subnet 400 ... IPv6 network 401 ... IPv6 server

Claims (4)

A mobile terminal that transmits and receives packets to and from a packet relay device while moving between a first network and a second network that are networks in an IPv4 environment or an IPv6 environment,
Movement detection means for receiving a signal output from an interface included in each network and detecting movement from the first network to the second network;
Registration request means for transmitting a registration request to the packet relay device;
An IPv4 tunnel creating means for receiving a registration response to the registration request from the packet relay device and creating an IPv4 / IPv4 tunnel based on the registration response;
An IPv4 IPv6 tunnel creating means for receiving a registration response to the registration request from the packet relay device and creating an IPv4 / IPv6 tunnel based on the registration response;
If the destination second network is an IPv4 environment, an IPv4 route control means for controlling the route so as to perform packet transfer with the packet relay device via the IPv4 / IPv4 tunnel;
A mobile terminal comprising: an IPv6 route control means for performing route control so that packet transfer with the packet relay device is performed via the IPv4 / IPv6 tunnel when the second network of the destination is an IPv6 environment . A packet relay apparatus that performs packet transfer with a mobile terminal that moves between a first network and a second network that are networks in an IPv4 environment or an IPv6 environment,
Authentication means for receiving a registration request from the mobile terminal, authenticating the registration request, and detecting that the mobile terminal has moved from the first network to the second network;
When the authentication is normally performed, an IPv4 tunnel creating unit that sends a registration response to the registration request to the mobile terminal and creates an IPv4 / IPv4 tunnel based on the registration request;
If the authentication is normally performed, an IPv4 / IPv6 tunnel creating means for sending a registration response to the registration request to the mobile terminal and creating an IPv4 / IPv6 tunnel based on the registration request;
If the second network is an IPv4 environment, an IPv4 route control means for performing route control so as to perform packet transfer with the mobile terminal via the IPv4 / IPv4 tunnel;
If the second network is in an IPv6 environment, the packet relay apparatus further comprises an IPv6 route control means for performing route control so that packet transfer with the mobile terminal is performed via the IPv4 / IPv6 tunnel. A communication system comprising: a mobile terminal that moves between a first network and a second network that are networks in an IPv4 environment or an IPv6 environment; and a packet relay device that transmits and receives packets to and from the mobile terminal,
Movement detection means for detecting movement from the first network to the second network, receiving a signal output from an interface included in each network, registration request means for transmitting a registration request to the packet relay apparatus, and the packet relay A registration response to the registration request from the device; an IPv4 tunnel creation means for creating an IPv4 / IPv4 tunnel based on the registration response; a registration response to the registration request from the packet relay device; IPv4 / IPv6 tunnel creating means for creating an IPv4 / IPv6 tunnel in IPv4, and if the second network at the movement destination is an IPv4 environment, the route control is performed so that the packet transfer with the packet relay device is performed via the IPv4 / IPv4 tunnel. Route control means and destination If the second network is an IPv6 environment, a mobile terminal having an IPv6 path control means for routing to the packet transfer performed via the IPv4 / IPv6 tunnel with the packet relay device, respectively,
An authentication unit that receives a registration request from the mobile terminal, authenticates the registration request, and detects that the mobile terminal has moved from the first network to the second network; when the authentication is normally performed, IPv4 tunnel creating means for creating an IPv4 / IPv4 tunnel based on a registration request, IPv4 IPv6 tunnel creating means for creating an IPv4 / IPv6 tunnel based on the registration request when the authentication is normally performed, and the second network is configured as IPv4 If the environment is an environment, IPv4 route control means for controlling the packet transfer with the mobile terminal via the IPv4 / IPv4 tunnel, and if the second network is an IPv6 environment, the packet transfer with the mobile terminal That performs routing through the IPv4 / IPv6 tunnel Communication system, comprising a packet relay apparatus having a 6 path control means, respectively. A mobile terminal that moves between a first network and a second network, which are networks in an IPv4 environment or an IPv6 environment, and transmits / receives a packet to / from a packet relay apparatus receives a signal output from an interface included in each network, and A movement detecting step for detecting movement from a network to the second network;
An authentication step in which the mobile terminal transmits a registration request to the packet relay device, and the packet relay device authenticates the registration request received from the mobile terminal;
The mobile terminal receiving a registration response to the registration request from the packet relay device, and creating an IPv4 / IPv4 tunnel based on the registration response;
The mobile terminal receiving a registration response to the registration request from the packet relay device, and creating an IPv4 / IPv6 tunnel based on the registration response;
If the second network to which the mobile terminal is moving is an IPv4 environment, routing the packet transfer with the packet relay device via the IPv4 / IPv4 tunnel;
If the second network to which the mobile terminal is moving is an IPv6 environment, routing the packet transfer with the packet relay device via the IPv4 / IPv6 tunnel;
When the authentication is normally performed, the packet relay device creates an IPv4 / IPv4 tunnel based on the registration request;
When the authentication is normally performed, the packet relay device creates an IPv4 / IPv6 tunnel based on the registration request;
If the second network is in an IPv4 environment, the packet relay device performs route control so as to perform packet transfer with the mobile terminal via the IPv4 / IPv4 tunnel;
If the second network is in an IPv6 environment, the packet relay device includes a step of routing so that packet transfer with the mobile terminal is performed via the IPv4 / IPv6 tunnel.

Images