When a first mobile node is moved, it reports binding information including a compatible node identifier (virtual mobile guaranteed general network identifier and a node identifier) and a compatible position identifier to a first server which is assigned to the first mobile node. A second mobile node reports the binding information to a second server. For communicating with the second mobile node to which a second server is assigned, if the destination address of a packet addressed to the second mobile node is designated with a compatible node identifier, the first mobile node acquires the binding information of the second mobile node from the second server. Then, the first mobile node converts the destination address of the packet into the acquired compatible position identifier and sets the compatible position identifier of the first mobile node as the source address of the packet. The first mobile node then transmits the packet.