A TCP message consisting of 2100 bytes is passed to IP for delivery across two…
2004
A TCP message consisting of 2100 bytes is passed to IP for delivery across two networks. The first network can carry a maximum payload of 1200 bytes per frame and the second network can carry a maximum payload of 400 bytes per frame, excluding network overhead. Assume that IP overhead per packet is 20 bytes. What is the total IP overhead in the second network for this transmission?
- A.
40 bytes
- B.
80 bytes
- C.
120 bytes
- D.
160 bytes
Attempted by 135 students.
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Correct answer: C
Key insight: packets on the second network can carry at most 400 bytes of payload and each IP packet adds a 20-byte header.
Determine how many IP fragments are required on the second network: number of fragments = ceil(2100 / 400) = 6.
Each fragment carries a 20-byte IP header on that network, so total IP overhead = 6 × 20 = 120 bytes.
Answer: The total IP overhead on the second network is 120 bytes.
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