CONFIRMATION SYSTEM, COMMUNICATION SYSTEM, CONFIRMATION SERVER DEVICE, CONFIRMATION METHOD, AND, PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a confirmation server device and the like which can appropriately determine a communication protocol available by a terminal device. SOLUTION: A terminal device transmits a TCP previous notice packet (301), a confirmation server device returns a confirmation packet (302), and the terminal device then transmits a UDP trial packet (303). If the trial packet can be received within a fixed period of time after the reception of the previous notice packet, the confirmation server device determines that the terminal device is enabled to transmit a UDP packet to an external communication apparatus. The confirmation server device transmits a previous notice packet from a first IP address (304), the terminal device returns a confirmation packet (305) and the confirmation server than transmits a UDP trial packet from a second IP address (306). If the trial packet can be received within a fixed period of time after the reception of the previous notice packet, the terminal device determines that the terminal device is enabled to receive a UDP packet from an external communication apparatus. COPYRIGHT: (C)2010,JPO&INPIT