Abstract: In order to continue a communication by performing a handover across or between different communication systems, improvement in redundancy of a communication route and a delay time difference before and after switching the communication system is intended. A bicast entity 21 includes, when a wireless terminal 10 makes a connection and continues a communication across different communication systems 20X and 20Y, bicast means for delivering a packet for each communication route via each of the communication systems 20X and 20Y before and after switching the communication system to which the above described wireless terminal 10 connects, and control means for completing a relay of the packet when the switching of the communication system to which the above described wireless terminal 10 connects is completed.

Abstract: A session control method for radio terminals that implements a Multimedia Integrated network by Radio Access Innovation (MIRAI) such that selection of a radio access network does not impose a burden on each of the radio access networks, and an interface setup method for setting up IP connection quickly during switching of the radio access network. The Multimedia Integrated network by Radio Access Innovation (MIRAI) 10 includes heterogeneous radio access networks 11, Internet 12, and multimode radio terminals 13, and the heterogeneous radio access networks 11 includes a PHS network 11a, a wireless LAN 11b, a paging network 11c, and a cellular phone network 11d. The Internet 12 includes a CCN server 12a, which sends session-related information to the radio terminal 13 via the paging network 11c. The radio terminal 13 selects a radio IF and application that are appropriate for communication based on the session-related information, and establishes a session.