Project ForgeSuppose you are asked to design a new reliable byte-stream transport protocol like TCP. This protocol, named myTCP, runs over a 100 Mbps network with Round Trip Time of 150 milliseconds and the maximum segment lifetime of 2 minutes. Which of the following is/are valid lengths of the Sequence Number field in the myTCP header?
- A30 bits
- 32 bits
- 34 bits
- 36 bits
Explanation
Maximum bytes sendable within one MSL (2 min=120s) at 100Mbps = (100×10⁶×120)/8 = 1.5×10⁹ bytes. The sequence space (2ⁿ) must be at least this large to avoid wraparound within an MSL: 2³⁰≈1.07×10⁹ (too small), 2³¹≈2.15×10⁹ (sufficient) — so any n≥31 works. 30 bits is insufficient (invalid); 32, 34, and 36 bits are all valid (≥31).
Source: GATE CS 2023 (2023)
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