Round Trip Time (RTT) is used by TCP to estimate the amount of time that is needed for round trip communication between a sender and a receiver. Windows 2000 supports the use of the TCP Round Trip Time Measurement option to improve the way RTT is estimated. By calculating more accurate RTT information more often, TCP uses better estimates for setting retransmission timers, which helps improve overall TCP speed and performance.
Improvements in estimating RTT help significantly over longer roundtrip network links, such as WANs that span continents or that use either wireless or satellite communication links.
For more information about TCP roundtrip time measurement, see RFC 1323, "TCP Extensions for High Performance."