Abstract: Destination data communication device receives data to be distributed either directly from source data communication device or via another destination data communication device. For each destination data communication device, management data communication device receives, each time a predetermined interval has passed, a communication status data set indicating a communication speed for each communication party and a stored data volume data set indicating a volume of data to be distributed that has already been stored by each destination data communication device. Management data communication device determines a flexible arrangement of destination data communication devices and paths for transmission and reception of data between destination data communication devices based on the foregoing data. Each destination data communication device transmits data blocks to and receives data blocks from communication parties determined by management data communication device.

Abstract: A receiving side data communication device calculates, at prescribed times, an actual measured RTT, which is the time required for data to travel to a transmission side data communication device and back, a data transfer rate for the data transfer, and a data loss ratio, which is the ratio of the number of packets not received by the receiving side data communication device to the number of packets sent from the transmission side data communication device. The receiving side data communication device uses the most recent data transfer rate and the data loss ratio to calculate a transfer score according to a prescribed calculation formula, and increases or decreases the reference RTT in accordance with the change in the transfer score.

Abstract: Destination data communication device receives data to be distributed either directly from source data communication device or via another destination data communication device. For each destination data communication device, management data communication device receives, each time a predetermined interval has passed, a communication status data set indicating a communication speed for each communication party and a stored data volume data set indicating a volume of data to be distributed that has already been stored by each destination data communication device. Management data communication device determines a flexible arrangement of destination data communication devices and paths for transmission and reception of data between destination data communication devices based on the foregoing data. Each destination data communication device transmits data blocks to and receives data blocks from communication parties determined by management data communication device.

Abstract: A receiving side data communication device calculates, at prescribed times, an actual measured RTT, which is the time required for data to travel to a transmission side data communication device and back, a data transfer rate for the data transfer, and a data loss ratio, which is the ratio of the number of packets not received by the receiving side data communication device to the number of packets sent from the transmission side data communication device. The receiving side data communication device uses the most recent data transfer rate and the data loss ratio to calculate a transfer score according to a prescribed calculation formula, and increases or decreases the reference RTT in accordance with the change in the transfer score.