2. Why does the TCP sender congestion window increase and decrease time by time? TCP congestion control: additive increase multiplicative decrease approach: sender increases transmission rate (window size), probing for usable bandwidth, until loss occurs additive increase increase cwnd by 1 MSS every RTT until loss detected multiplicative decrease: cut cwnd in half after loss additively increase window size until loss occurs (then cut window in half) AIMD saw tooth behavior: probing for bandwidth 8 0 time