A technology is disclosed for certainly performing dynamic routing and error checking processes in the mobile network. According to this technology, the home agent sets up a Binding Acknowledgement message with a smaller Lifetime value when receiving a Binding Update message from a mobile router. During this smaller Lifetime, the mobile router can send a Routing Update message to the home agent. Thus, the home agent, for example, can check consistency of prefix information specified in the Biding Update with route installed by the Routing Update message. The present invention can be applied to both two distinct modes (explicit mode and implicit mode) that prefix information is specified in the Binding Update or not.