For internal data communication through a computer network, a 5-layer protocol…
2023
For internal data communication through a computer network, a 5-layer protocol hierarchy is proposed. Applications used in this network generate 270-byte messages. At each layer, a 6-byte header is added. What fraction of network bandwidth (in %) is wasted due to headers?
Answer: C. 10% — In a layered protocol hierarchy, every layer wraps the data handed to it with its own header before passing the result to the layer beneath, independently of…
- A.
5%
- B.
20%
- C.
10%
- D.
15%
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Correct answer: C
In a layered protocol hierarchy, every layer wraps the data handed to it with its own header before passing the result to the layer beneath, independently of what any other layer does. Because each layer contributes its own fixed-size header, the total header overhead across the hierarchy equals (number of layers) times (header size per layer), and the fraction of transmitted bandwidth consumed by headers is the total header bytes divided by the complete packet size — the original message plus all of that accumulated overhead.
This hierarchy has 5 layers, and each one adds its own 6-byte header, so the total header overhead is 5 x 6 = 30 bytes.
The original application message is 270 bytes, so the fully-headered packet size is 270 + 30 = 300 bytes.
The wasted-bandwidth fraction is the total header bytes divided by the total packet size: 30 / 300 = 0.10.
Expressed as a percentage, this is 10%.
As a check, 10% of the 300-byte packet is exactly 30 bytes, matching the header total computed above, so the result is internally consistent.
This exercise (a standard adaptation of the classic n-layer protocol-hierarchy problem) treats every layer named in the given hierarchy as contributing one header each; it is not modelling any specific real-world layer, such as a physical layer that only frames raw bits, separately, so all 5 stated layers count toward the header overhead.