Patent ID: 7009950

Claim:
A mobile IP network system comprising: a plurality of radio access networks each connected to mobile stations via radio links; and an IP network to which a home agent node and a plurality of packet nodes each for transferring IP packets destined for one of mobile stations and received from the home agent node to one of said radio access networks are connected, wherein each of the radio access networks has at least one base station controller and at least one radio base station which is connected to the base station controller to perform radio communications with a plurality of mobile stations, and wherein each of the base station controllers is connected to the plurality of packet nodes through a network, receives an identifier of a previous packet node from another base station controller when one of the mobile stations moved into a control area of the base station controller from a control area of the another base station controller belonging to another radio access network, and selects either the previous packet node which is communicating IP packets for the moved mobile station with said home agent node or a preliminarily designated specific packet node in accordance with a communication state of the mobile station, thereby to selectively carry out IP packet communication for the moved mobile station between the base station controller and the previous packet node using a previous identifier of a logical connection having been established between the previous packet node and the mobile station or IP packet communication between the base station controller and the specific packet node using an identifier of a new logical connection established between the specific packet node and the moved mobile station, after performing a registration procedure between the moved mobile station and said home agent node, depending on the communication state of the mobile station.