Patent ID: 6515974
Filing Date: 2003-02-04
Classification: H04L,H04W

Abstract:
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.