Project ForgeConsider the sliding window flow-control protocol operating between a sender and receiver over a full-duplex error-free link. The size of the data frame is 2000 bits and the acknowledgement frame is 10 bits. The link data rate in each direction is 1 Mbps, and the one-way propagation delay is 100 milliseconds. Processing times are negligible and the sender has infinite frames available. The minimum value of the sender's window size (rounded to the nearest integer) needed to achieve a link utilization of 50% is ____.
Explanation
Transmission time Tt = 2000 bits/1Mbps = 2ms. Round-trip time = 2×100 = 200ms. Full cycle = Tt+RTT = 202ms. For window size W, utilization = W·Tt/(Tt+RTT) = 2W/202. Setting this to 0.5 gives W = 0.5×202/2 = 50.5, which rounds to the nearest integer satisfying the ≥50% requirement: 51 (since W=50 gives 100/202≈49.5%, just under the target).
Source: GATE CS 2021 (Session 1 / Set-1) (2021)
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