TCP Round Trip Time and Timeout Q: how to set TCP Q: how to estimate rtt? timeout value? O SampleRTT: measured time from 口 longer than Rtt segment transmission until ACK o note: RTT will vary receipt 口 too short: premature o ignore retransmISSions, timeout cumulatively ACKed segments 口Samp1 eRTT wil‖ I vary,Want o unnecessar estimated rTT"smoother retransmissions o use several recent o too long: slow reaction to segment loss measurements, not just current SampleRTT 3: Transport Layer 3b-93: Transport Layer 3b-9 TCP Round Trip Time and Timeout Q: how to set TCP timeout value?  longer than RTT  note: RTT will vary  too short: premature timeout  unnecessary retransmissions  too long: slow reaction to segment loss Q: how to estimate RTT?  SampleRTT: measured time from segment transmission until ACK receipt  ignore retransmissions, cumulatively ACKed segments  SampleRTT will vary, want estimated RTT “smoother”  use several recent measurements, not just current SampleRTT