In the network a host reachability is obtained by a static identifier and a dynamic address is associated, the communication model to confirm the reachability, signals, a method and apparatus

摘要

A1 A communication system comprises obtaining a corresponding dynamic address by sending an identifier to a mapping notification system which stores a pair of an identifier and a dynamic address; and determining whether or not a dynamic address stored in the mapping notification system is correct by accessing other communication node to which the dynamic address obtained by the obtaining means is assigned. The system also compares the identifier sent to the mapping notification system and a reply for the access to the communication node. If the system determines that the address is not correct, the obtaining process and determination process are executed again, an execution of a process to be executed after the determination process is stopped, or a control process for preventing from sending back a reply of the address from the mapping notification system is executed.