Mobile computer communication scheme supporting moving among networks of different address systems

• US 20020191576A1
• Filed: 07/03/2002
• Published: 12/19/2002
• Est. Priority Date: 06/16/1998
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Inoue, Atsushi, Kumaki, Yoshinari
• Granted Patent: US 7,221,666 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5084 Providing for device mobility network addressing or numbering for mobility support in wireless networks H04W8/26; mobile IP H04W80/04
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A communication scheme for supporting data transfer to a visited site of a mobile terminal which moves across a private network operated by a private address system and an Internet operated by a global address system is disclosed. When the mobile terminal has moved from the first network to the second network, packets destined to an original home address of the mobile terminal on the first subnet are transferred from the first router device in the first subnet by setting an address of the first interface of a packet relay device as a care-of address of the mobile terminal. Then, the packets received by the packet relay device from the first router device at the first interface are transferred to the second router device in the second subnet through the second interface of the packet relay device, and the packets received by the second router device from the packet relay device are transferred to a current location address of the mobile terminal.

Claims

1. A communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system comprising:

a packet relay device having a first interface connected with the first network and a second interface connected with the second network;

a first router device provided at a first subnet in the first network, having a function for transferring packets destined to a home address of each mobile terminal belonging to the first subnet to a care-of address of each mobile terminal; and

a second router device provided at a second subnet in the second network;

wherein when a mobile terminal has moved from the first network to the second network, the first router device transfers packets destined to an original home address on the first subnet of the mobile terminal by setting an address of the first interface of the packet relay device as a care-of address of the mobile terminal, the packet relay device transfers the packets received from the first router device at the first interface to the second router device through the second interface, and the second router device transfers the packets received from the packet relay device to a current location address of the mobile terminal.

2. The communication system of claim 1, wherein when the mobile terminal moves to the second subnet, the mobile terminal acquires a new home address on the second subnet and notifies a pair information on the original home address and the new home address to the second router device, the second router device transfers the pair information notified from the mobile terminal to the packet relay device, the packet relay device stores the original home address and the new home address according to the pair information transferred from the second router device and transfers the pair information to the first router device, and the first router device sets the address of the first interface of the packet relay device as the care-of address of the mobile terminal identified by the original home address contained in the pair information transferred from the packet relay device.

3. The communication system of claim 1, wherein when the mobile terminal moves to the second subnet, the mobile terminal acquires a new home address on the second subnet, and while the mobile terminal is located at the second subnet, the second router device transfers the packets received from the packet relay device by setting the new home address as the current location address of the mobile terminal.

4. The communication system of claim 1, wherein when the mobile terminal has further moved from the second subnet to a third subnet within the second network, the second router device registers a new care-of address on the third subnet of the mobile terminal upon receiving a mobility registration message from the mobile terminal, and transfers the packets received from the packet relay device by setting the new care-of address as the current location address of the mobile terminal.

5. The communication system of claim 1, wherein the second router device transfers a mobility registration message received from the mobile terminal to the first router device via the packer relay device when the second router device judges that the mobile terminal has newly moved into the second network from the first network, and the first router device sets the address of the first interface of the packet relay device as the care-of address of the mobile terminal identified by the mobility registration message transferred from the second router device via the packet relay device.

6. The communication system of claim 5, wherein the second router device stores an immediately previous care-of address of the mobile terminal, and judges that the mobile terminal has newly moved into the second network from the first network when the immediately previous care-of address is an address on the first network.

7. The communication system of claim 1, wherein the first router device includes:

a first management unit for managing the original home address of the mobile terminal;

a second management unit for managing the care-of address of the mobile terminal; and

a transfer unit for receiving the packets destined to the original home address managed by the first management unit on behalf of the mobile terminal, and transferring the packets to the care-of address managed by the second management unit, when the mobile terminal is currently not located at the original home address.

8. The communication system of claim 7, wherein when the mobile terminal has moved from the first subnet to another subnet within the first network, the second management unit stores an address of another router device for relaying the packets which is provided for said another subnet or an address allocated to the mobile terminal in said another subnet as the care-of address.

9. The communication system of claim 7, wherein when the mobile terminal has moved from the first subnet to the second subnet, the second management unit stores the address of the first interface of the packet relay device as the care-of address.

10. The communication system of claim 1, wherein when the mobile terminal moves to the second subnet, the mobile terminal acquires a new home address on the second subnet and notifies a pair information on the original home address and the new home address to the packet relay device, and the packet relay device includes:

a message analysis unit for obtaining a correspondence between the original home address and the new home address along with information on the first and second router devices, by analyzing the pair information transferred from the mobile terminal; and

an address translation unit for translating a receiving interface side address contained in a packet from one of the first interface and the second interface into a corresponding transmitting interface side address according to the correspondence obtained by the message analysis unit, at a time of transferring the packet to another one of the first interface and the second interface.

11. The communication system of claim 1, wherein the first router device stops transferring the packets destined to the original home address of the mobile terminal, to the first interface, when:

(1) a prescribed lifetime set for the mobile terminal expires;

(2) the mobile terminal makes a second mobility registration associated with a moving of the mobile terminal, to the second router device at the second network;

or (3) a currently executed communication job of the mobile terminal is finished.

12. The communication system of claim 1, wherein one of the first network and the second network is operated by a private address system while another one of the first network and the second network is operated by a global address system.

13. The communication system of claim 1, wherein the first network and the second network are operated by mutually different private address systems and interconnected through another network operated by a global address system.

16. The communication system of claim 15, wherein when the mobile terminal has moved from the first subnet to another subnet within the first network, the second management unit stores an address of another router device for relaying the packets which is provided for said another subnet or an address allocated to the mobile terminal in said another subnet as the care-of address.

17. The communication system of claim 15, wherein when the mobile terminal has moved from the first subnet to the second subnet, the second management unit stores the address of the first interface as the care-of address.

14. A method of data packet transfer in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a packet relay device having a first interface connected with the first network and a second interface connected with the second network, a first router device provided at a first subnet in the first network, the first router device having a function for transferring packets destined to a home address of each mobile terminal belonging to the first subnet to a care-of address of each mobile terminal, and a second router device provided at a second subnet in the second network, the method comprising the steps of:

(a) when a mobile terminal has moved from the first network to the second network, transferring packets destined to an original home address of the mobile terminal on the first subnet from the first router device by setting an address of the first interface of the packet relay device as a care-of address of the mobile terminal;

(b) transferring the packets received by the packet relay device from the first router device at the first interface to the second router device through the second interface; and

(c) transferring the packets received by the second router device from the packet relay device to a current location address of the mobile terminal.

15. A router device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a packet relay device having a first interface connected with the first network and a second interface connected with the second network, the router device being provided at a subnet in the first network and comprising:

a first management unit for managing an original home address on the subnet of a mobile terminal for which the subnet is an original home network;

a second management unit for managing a care-of address of the mobile terminal; and

a transfer unit for receiving packets destined to the original home address managed by the first management unit on behalf of the mobile terminal, and transferring the packets to the care-of address managed by the second management unit, when the mobile terminal is currently not located at the original home address, such that when the mobile terminal has moved from the first network to the second network, the router device transfers packets destined to the original home address by setting an address of the first interface of the packet relay device as the care-of address.

18. A router device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a packet relay device having a first interface connected with the first network and a second interface connected with the second network, the router device being provided at a subnet in the second network and comprising:

a first management unit for managing a new home address on the subnet of a mobile terminal for which the subnet is a new home network;

a second management unit for managing a current location address of the mobile terminal;

a message transfer unit for transferring to the packet relay device a pair information on an original home address that has been allocated to the mobile terminal in the first network and the new home address of the mobile terminal transmitted from the mobile terminal and managed by the first management unit, when the mobile terminal has moved from the first network to the second network, such that the packer relay device transfers packets destined to the original home address and received at the first interface to the router device through the second interface; and

a packet transfer unit for transferring the packets received from the packet relay device to the current location address of the mobile terminal managed by the second management unit.

19. A packer relay device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a first router device provided at a first subnet in the first network and a second router device provided at a second subnet in the second network, the packet relay device being provided between the first network and the second network and comprising:

a first interface connected with the first network.;

a second interface connected with the second network;

a message reception unit for receiving through the second interface a pair information on an original home address of a mobile terminal on the first subnet and a new home address acquired by the mobile terminal on the second subnet when the mobile terminal moves from the first network to the second network, the pair information being notified by the mobile terminal;

a message analysis unit for obtaining the original home address and the new home address along with information on the first and second router devices, by analyzing the pair information received by the message reception unit;

a message transmission unit for transmitting a message to the first router device through the first interface, such that the first router device transfers packets destined to the original home address to the first interface; and

a packet transfer unit for transferring the packets received at the first interface to the second router device through the second interface by using the new home address, such that the second router device transfers the packets to the mobile terminal.

20. A computer usable medium having computer readable program code means embodied therein for causing a computer to function as a router device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a packet relay device having a first interface connected with the first network and a second interface connected with the second network, the router device being provided at a subnet in the first network and the computer readable program code means includes:

first computer readable program code means for causing said computer to manage an original home address on the subnet of a mobile terminal for which the subnet is an original home network;

second computer readable program code means for causing said computer to manage a care-of address of the mobile terminal; and

third computer readable program code means for causing said computer to receive packets destined to the original home address managed by the first computer readable program code means on behalf of the mobile terminal, and transfer the packets to the care-of address managed by the second computer readable program code means, when the mobile terminal is currently not located at the original home address, such that when the mobile terminal has moved from the first network to the second network, the router device transfers packets destined to the original home address by setting an address of the first interface of the packet relay device as the care-of address.

21. A computer usable medium having computer readable program code means embodied therein for causing a computer to function as a router device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a packet relay device having a first interface connected with the first network and a second interface connected with the second network, the router device being provided at a subnet in the second network and the computer readable program code means includes:

first computer readable program code means for causing said computer to manage a new home address on the subnet of a mobile terminal for which the subnet is a new home network;

second computer readable program code means for causing said computer to manage a current location address of the mobile terminal;

third computer readable program code means for causing said computer to transfer to the packet relay device a pair information on an original home address that has been assigned to the mobile terminal in the first network and the new home address of the mobile terminal transmitted from the mobile terminal and managed by the first computer readable program code means, when the mobile terminal has moved from the first network to the second network such that the packer relay device transfers packets destined to the original home address and received at the first interface to the router device through the second interface; and

fourth computer readable program code means for causing said computer to transfer the packets received from the packet relay device to the current location address of the mobile terminal managed by the second computer readable program code means.

22. A computer usable medium having computer readable program code means embodied therein for causing a computer to function as a packer relay device for use in a communication system for supporting data packet transfer with respect to mobile terminals capable of carrying out communications while moving among networks, in a first network and a second network which are operated by mutually different address systems and which are capable of accommodating the mobile terminals, the communication system including a first router device provided at a first subnet in the first network and a second router device provided at a second subnet in the second network, the packet relay device being provided between the first network and the second network and having a first interface connected with the first network and a second interface connected with the second network, and the computer readable program code means includes:

first computer readable program code means for causing said computer to receive a pair information on an original home address of a mobile terminal on the first subnet and a new home address acquired by the mobile terminal on the second subnet when the mobile terminal moves from the first network to the second network, the pair information being notified by the mobile terminal through the second interface;

second computer readable program code means for causing said computer to obtain the original home address and the new home address along with information on the first and second router devices, by analyzing the pair information received by the first computer readable program code means;

third computer readable program code means for causing said computer to transmit a message to the first router device through the first interface, such that the first router device transfers packets destined to the original home address to the first interface; and

fourth computer readable program code means for causing said computer to transfer the packets received at the first interface to-the second router device through the second interface by using the new home address, such that the second router device transfers the packets to the mobile terminal.