A mobile supporting router device for realizing the handoff control
associated with the moving in high speed is forms by at least one first
interface connected with radio base stations, each capable of
accommodating at least one mobile terminal; at least one second interface
connected with a wire network; an information exchanging unit for
exchanging a routing protocol on a network layer, through the second
interface; a memory unit for storing information regarding a routing on
the network layer based on the routing protocol exchanged by the
information exchanging unit; a transfer unit for transferring datagram
through the first interface according to the information regarding the
routing on the network layer stored in the memory unit; a moving
detection unit for detecting a moving of the mobile terminal among the
radio base stations; and an information updating unit for updating the
information regarding the routing on the network layer stored in the
memory unit when the moving of the mobile terminal is detected by the
moving detection unit.