CNT 4713 Lecture Notes - Lecture 8: Bitstream
Document Summary
Selective repeat: receiver individually acknowledges all correctly received pkts buffers pkts, as needed, for eventual in-order delivery to upper layer sender only resends pkts for which ack not received sender timer for each unacked pkt sender window. N consecutive seq #"s limits seq #s of sent, unacked pkts. Need 2n+1 where n is num of packets. Limited by link layer & its mtu max transmission unit = largest piece of data it can send. Tcp seq. numbers, acks: sequence numbers: byte stream number of first byte in segment"s data. Acknowledgements: seq # of next byte expected from other side cumulative ack. A: tcp spec doesn"t say, - up to implementor. Tcp round trip time, timeout: exponential weighted moving average influence of past sample decreases exponentially fast typical value: = 0. 125 timeout interval: estimatedrtt plus safety margin large variation in estimatedrtt -> larger safety margin estimate samplertt deviation from estimatedrtt:
