Communication system, retransmission control method, receiving side device, and sending side device

A retransmission control method in a communication system that performs communication between a transmitter at a transmission-side and a receiver at a reception-side on a basis of a transmission control protocol (TCP), wherein:

• a route switching time zone is a time zone in which a communication route between the transmitter and the receiver is switched from a first communication route to a second communication route,
• the retransmission control method comprising:
• processing of prohibiting transmission of a retransmission request related to a first packet from the receiver to the transmitter during a first time from detection of packet missing when the packet missing of the first packet is detected by the receiver in the route switching time zone;
• and
• processing of transmitting the retransmission request related to the first packet from the receiver to the transmitter when the receiver does not receive the first packet during the first time.

A reception-side device that performs communication with a transmitter at a transmission-side on a basis of a transmission control protocol (TCP), the reception-side device comprising:

• circuitry configured to perform retransmission control, wherein:
• a route switching time zone is a time zone in which a communication route between the transmitter and the reception-side device is switched from a first communication route to a second communication route, and
• the circuitry is further configured to:
• prohibit transmission of a retransmission request related to a first packet to the transmitter during a first time from detection of packet missing when the packet missing of the first packet is detected in the route switching time zone, and
• transmit the retransmission request related to the first packet to the transmitter when the first packet is not received during the first time.