Congestion Avoidance If loss occurs when cwnd= W Network can handle 0.5W-W segments Set cwnd to 0.5W(multiplicative decrease) Upon receiving ACK Increase cwnd by(1 packet)/cwnd What is 1 packet?>1 MSS worth of bytes After cwnd packets have passed by approximately increase of 1 MSs Implements AIMD Lecture 19: TCP Congestion ControlLecture 19: TCP Congestion Control 9 Congestion Avoidance • If loss occurs when cwnd = W • Network can handle 0.5W ~ W segments • Set cwnd to 0.5W (multiplicative decrease) • Upon receiving ACK • Increase cwnd by (1 packet)/cwnd • What is 1 packet?  1 MSS worth of bytes • After cwnd packets have passed by  approximately increase of 1 MSS • Implements AIMD