Packet transfer system, relay device, packet transfer method, and program
In a packet transfer system, a transmission-side relay device extracts and integrates data included in a packet transmitted from a transmission device to obtain a packet data stream, extracts data from the packet data stream to obtain a data block, encodes the data block with an error correction code to generate redundant data as a redundant block, generates an error correction data stream obtained by integrating the data block and the redundant block, and packetizes the error correction data stream and transmits the packetized error correction data stream. A reception-side relay device restores missing data using redundant data included in the received data in a case in which there is missing data. The system enables packet transmission and reception to be efficiently performed even in a high loss rate environment.
1. A packet transfer system in which a transmission-side relay device and a reception-side relay device transfer data transmitted from a transmission device to a reception device according to TCP/IP protocol,
wherein the transmission-side relay device includes a first integrated circuit in communication with a first recording medium, the first recording medium storing a first computer program which, when executed by the first integrated circuit, causes the first integrated circuit to perform functions including,
extracting first data included in a first packet transmitted from the transmission device and integrating the first data with data from other packets to obtain a packet data stream,
extracting second data having a predetermined block size determined in advance from the packet data stream to obtain a data block,
encoding the data block with an error correction code to obtain a redundant block of redundant data,
integrating the data block and the redundant block into an error correction data stream, and
packetizing the error correction data stream and transmitting the packetized error correction data stream to the reception-side relay device, and
wherein the reception-side relay device includes a second integrated circuit in communication with the first integrated circuit and a second recording medium, the second recording medium storing a second computer program which, when executed by the second integrated circuit, causes the second integrated circuit to perform functions including,
receiving the packetized error correction data stream transmitted from the transmission-side relay device,
restoring missing data using the redundant data included in the packetized error correction data stream in a case in which there is missing first data to produce a corrected packet data stream,
packetizing the corrected packet data stream to produce a packetized packet data stream and transmitting the packetized packet data stream to the reception device, and
requesting the transmission-side relay device to retransmit the missing data when the missing data cannot be restored using the redundant data.
2. The packet transfer system according to claim 1 ,
wherein
the first computer program further causes the first integrated circuit to perform a function of retransmitting the missing data to the reception-side relay device and controlling a congestion window when receiving the retransmission request.
3. The packet transfer system according to claim 1 ,
wherein the second computer program does not cause the second integrated circuit to perform the function of requesting the transmission-side relay device to retransmit the missing data when the missing data can be restored using the redundant data.
4. A relay device that functions as a transmission-side relay device in a packet transfer system in which the transmission-side relay device and a reception-side relay device transfer data transmitted from a transmission device to a reception device according to TCP/IP protocol, the relay device comprising a first integrated circuit in communication with a first recording medium, the first recording medium storing a first computer program which, when executed by the first integrated circuit, causes the first integrated circuit to perform functions including,
extracting first data included in a first packet transmitted from the transmission device and integrating the first data with data from other packets to obtain a packet data stream;
extracting second data having a predetermined block size determined in advance from the packet data stream to obtain a data block;
encoding the data block with an error correction code to obtain a redundant block of redundant data;
integrating the data block and the redundant block into an error correction data stream,
packetizing the error correction data stream and transmitting the packetized error correction data stream to the reception-side relay device; and
retransmitting the missing reception-side relay device responsive to receiving the retransmission request from the reception side relay device when the missing data cannot be restored using the redundant data by the reception-side relay device.
5. A relay device that functions as a reception-side relay device in a packet transfer system in which a transmission-side relay device and the reception-side relay device transfer data transmitted from a transmission device to a reception device according to TCP/IP protocol,
wherein the transmission-side relay device includes a first integrated circuit in communication with a first recording medium, the first recording medium storing a first computer program which, when executed by the first integrated circuit, causes the first integrated circuit to perform functions including,
extracting first data included in a first packet transmitted from the transmission device and integrating the first data with data from other packets to obtain a packet data stream,
extracting second data having a predetermined block size determined in advance from the packet data stream to obtain a data block,
encoding the data block with an error correction code to obtain a redundant block of redundant data,
integrating the data block and the redundant block into an error correction data stream, and
packetizing the error correction data stream and transmitting the packetized error correction data stream to the reception-side relay device, and
wherein the reception-side relay device includes a second integrated circuit in communication with the first integrated circuit and a second recording medium, the second recording medium storing a second computer program which, when executed by the second integrated circuit, causes the second integrated circuit to perform functions including,
receiving the packetized error correction data stream transmitted from the transmission-side relay device;
restoring missing data using the redundant data included in the packetized error correction data stream in a case in which there is missing first data to produce a corrected packet data stream;
packetizing the corrected packet data stream to produce a packetized packet data stream and transmitting the packetized packet data stream to the reception device; and
requesting the transmission-side relay device to retransmit the missing data when the missing data cannot be restored using the redundant data.
6. A packet transfer method in which a transmission-side relay device and a reception-side relay device transfer data transmitted from a transmission device to a reception device according to TCP/IP protocol,
wherein the transmission-side relay device
extracts first data included in a first packet transmitted from the transmission device and integrating the first data with data from other packets to obtain a packet data stream,
extracts second data having a predetermined block size determined in advance from the packet data stream to obtain a data block,
encodes the data block with an error correction code to obtain a redundant block of redundant data,
integrates the data block and the redundant block into an error correction data stream, and
packetizes the error correction data stream and transmits the packetized error correction data stream to the reception-side relay device, and
wherein the reception-side relay device
receives the packetized error correction data stream transmitted from the transmission-side relay device,
restores missing data using the redundant data included in the packetized error correction data stream in a case in which there is missing first data to produce a corrected packet data stream,
packetizes the corrected packet data stream to produce a packetized packet data stream and transmits the packetized packet data stream to the reception device, and
requests the transmission-side relay device to retransmit the missing data when the missing data cannot be restored using the redundant data.