COMMUNICATION KEEPING SYSTEM, TERMINAL DEVICE, COMMUNICATION KEEPING METHOD, AND CONNECTION KEEPING PROGRAM

摘要

A connection management unit (91) sets a sustained connection with a server device (80) by designating an extension interval. A packet transmission unit (81) transmits a keep-alive packet to a terminal device (90) upon the elapse of the extension interval designated by the setting of the sustained connection. The connection management unit (91), upon the elapse of a high-reliability interval since the setting of the sustained connection, sets a new sustained connection with the server device (80) designating an extension interval determined in accordance with the reception state of the keep-alive packet, and, upon reception of the keep-alive packet based on the new sustained connection from the server device (80), sets the extension interval designated by the setting of the sustained connection as the high-reliability interval.