Patent ID: 7689644

Claim:
A communication system including a distribution server which distributes a multicast packet for broadcast, a client which receives the multicast packet via a network, a backup server, and a communication control device, wherein the backup server comprises: a first receiving device which receives the multicast packet from the distribution server; a generation device which appends a delay to the received multicast packet and changes a destination of the delayed multicast packet in order to generate a first backup packet and which generates a second backup packet by changing a destination of the received multicast packet without appending a delay; and a sending device which sends the first backup packet and the second backup packet to the network, wherein the communication control device comprises: a monitor device which monitors a receiving status of the multicast packet; a second receiving device which receives the first backup packet and the second backup packet when the monitor device detects interruption of the receipt of the multicast packet because of a problem; a conversion device which changes a destination of the first backup packet and the second backup packet to the destination of the multicast packet; and a distribution device which distributes the first backup packet and the second backup packet for which the conversion device changed the destination.