A network has a data transmission bandwidth of 20×10^6 bits per second. It…
2016
A network has a data transmission bandwidth of 20×10^6 bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 microseconds. The minimum size of a frame in the network is bytes.
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Correct answer: 200
Key insight: to detect a collision in CSMA/CD, a station must be transmitting for at least twice the maximum signal propagation time.
Required transmission time = 2 × maximum propagation time = 2 × 40 μs = 80 μs.
Bits needed = bandwidth × required transmission time = 20 × 10⁶ bits/s × 80 × 10⁻⁶ s = 1600 bits.
Convert to bytes: 1600 bits ÷ 8 = 200 bytes.
Therefore the minimum frame size in the network is 200 bytes.
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