A router, if judging that a routing function is impossible to execute, sends out a connection instruction message including the address of a terminal on a local network terminating the relaying flow, to another router to solicit switching. The router having received the connection instruction message starts a process for connecting with an external network while executing a process for link connection with a terminal, and then sends out a connection completion notice message when the connection with both the external network and the terminal is established. This process enables the router to switch a path rapidly.