Question

How does TCP determine the round trip time and time out interval?

Discuss the algorithm.

Answer 1

The RTT or round-trip time is also known as the RTD or round-trip delay time in telecommunications. It refers to the amount of time taken to send a signal and the amount of time taken to acknowledge its receipt. So this time delay refers to the propagation times between two points of a signal.

The timeout and retransmission strategy is a critical element of any implementation. The TCP sets a timeout when it sends data. It retransmits the data if the data is not acknowledged when the timeout expires.

TCP judges the need for a retransmission on the basis of the RTO or the retransmission timeout. If a packet does not receive and ACK in the time frame set it is retransmitted. Every time there is a retransmit the RTO for that packet doubles.