Project ForgeComputer Networks
Transport Protocols & IP Addressing
GATE 2022
Hard
Consider the data transfer using TCP over a 1 Gbps link. Assuming that the maximum segment lifetime (MSL) is set to 60 seconds, the minimum number of bits required for the sequence number field of the TCP header, to prevent the sequence number space from wrapping around during the MSL, is ____.
33
Explanation
Maximum bytes sendable in one MSL = (1×10⁹ bits/s × 60 s)/8 bits/byte = 6×10¹⁰/8 = 7.5×10⁹ bytes. To avoid the sequence number wrapping around within this window, the sequence space (2ⁿ) must exceed this: 2³²≈4.29×10⁹ is too small, but 2³³≈8.59×10⁹ ≥ 7.5×10⁹ — so n=33 bits minimum.
Source: GATE CS 2022 (2022)
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