| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To satisfy both reliability and efficiency of data communication between a transmitting device and a plurality of receiving devices while avoiding an excessive increase in the load imposed on communication networks linking the transmitting device and the plurality of receiving devices. <P>SOLUTION: In the transmitting device of this communication system where transmission object data are divided into a plurality of divided block data, and respective divided data are written in a data part, the system has a processing of a packet having in its header including an identifier of the divided data which uniquely identify the divided data is sent by a multicast transmission, and also a processing, when retransmission of previously transmitted divided data are requested from any one of receiving devices, that the packet is sent as a unicast transmission to the requesting receiving device. On the other hand, for each receiver, the presence/absence of the divided data is determined from an identifier of the divided data written in the header of the received packet, and if the divided data is absent, the retransmission of the data is requested to the transmitting device. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
