Method and system of reducing handover time in mobile IP network

A method and system of reducing handover time in a mobile IP network. An Foreign Agent (FA), when a terminal carries out a handover between mobile Internet Protocol Version-4 (IPv4) sub-networks of the Foreign Agent (FA), identifies whether or not a registration request message from the terminal is transmitted from an entry of a visitor list of the Foreign Agent (FA). If the registration request message is transmitted from the entry of the visitor list, interface information of a corresponding one of the sub-networks, to which the terminal registered in the visitor list is connected, is updated. A registration reply message is generated in response to the registration request message, and is transmitted to the terminal.