Patent ID: 7221666
Filing Date: 2007-05-22
Classification: H04L,H04W

Abstract:
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 directly connected with the first network and a second interface directly 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 on the first network, 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 on the second network; and 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.