Patent ID: 7133407

Claim:
A data communications system in which a transmitting side relay device and a receiving side relay device are connected to a first and second networks, respectively, where a prescribed transfer unit is consecutively transferred at a specific transfer rate and with prescribed transfer delay, and a data stream generated as a series of the transfer units are communicated as a series of datagram type packets, including the transfer unit, via a third network, said transmitting side relay device, comprising: an additional information generation unit generating additional information, including information about relationship between each transfer unit and the data stream based on the characteristics of the data stream; a packet generation unit generating a packet by attaching both the additional information and header information suited to be transferred in the third network when each transfer unit composing the data stream is inputted; and a transmitting unit transmitting the packet to the third network according to prescribed procedures, and said receiving side relay device, comprising: a separation unit separating the additional information and a transfer unit which are included in the packet received from the third network; an analysis unit analyzing the additional information separated by the separation unit; a reproduction unit locating information that is included in the transfer unit received from the separation unit in a correct position of the data stream and reproducing the data stream based on an analysis result by the analysis unit; and an outputting unit outputting the data stream reproduced by the reproduction unit to the second network.