Project ForgeConsider a TCP connection between a client and a server with the following specifications: the round trip time is 6 ms, the size of the receiver advertised window is 50 KB, slow-start threshold at the client is 32 KB, and the maximum segment size is 2 KB. The connection is established at time t = 0. Assume that there are no timeouts and errors during transmission. Then the size of the congestion window (in KB) at time t + 60 ms after all acknowledgements are processed is ____.
Explanation
cwnd starts at 1 MSS=2 KB and doubles each RTT (slow start) until reaching ssthresh=32 KB: after RTT1(t=6)=4, RTT2(t=12)=8, RTT3(t=18)=16, RTT4(t=24)=32 KB (=ssthresh, switch to congestion avoidance from here). Congestion avoidance adds 1 MSS=2 KB per RTT: RTT5(t=30)=34, RTT6(t=36)=36, RTT7(t=42)=38, RTT8(t=48)=40, RTT9(t=54)=42, RTT10(t=60)=44 KB.
Source: GATE CS 2020 (2020)
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