MULTICAST DATA COMMUNICATION METHOD, MULTICAST DATA COMMUNICATION SYSTEM, RELAY APPARATUS, RELAY METHOD, RELAY PROGRAM, MEDIUM STORED WITH RELAY PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a multicast data communication system, which is secured to a high degree that the problem of many unproductive tables due to attack by a malicious user being generated on nodes in a network is prevented. SOLUTION: Reception hosts 22-1 trough 22-4 periodically send reception request packets to a transmission host. A relay node 21, upon receiving the reception request packets and then receiving distribution table generating packets or data packets from the transmission host, generates a distribution table for the transmission host, if the table does not exist, and registers the addresses of the respective hosts 22-1 through 22-4, and the arrival time of the reception request packets and sends the reception request packets to the transmission host periodically. Upon receiving the data packet from the transmission host, the node 21 duplicates data packets, to send them only to the reception hosts whose reception request packets registered in the distribution table arrive within a prescribed time, when the data packets arrive.