Question

A 2 km long broadcast LAN has ${10}^7$ bps bandwidth and uses CSMA?CD. The signal travels along the wire at $2\times {10}^8$ m/s. What is the minimum packet size that can be used on this network?

• A. 50 bytes
• B. 200 bytes
• C. 100 bytes
• D. None of these

Answer 1

The correct option is D None of these

Is CSMA/CD the minimum frame size
$2\times z\times datarate$ (Bandwidth)
$\therefore z=\frac{d}{v}=\frac{distance}{velocity}$
$d=2km=2\times {10}^3$ m
$v=2\times {10}^8$ m/sec.
Data rate $={10}^7$ bps
$z=\frac{d}{v}=\frac{2\times {10}^{3}m}{2\times {10}^{8}m/sec}={10}^{-5}$ sec
$\therefore$ Minimum packet size $=2^{\ast }{10}^{-5}\ast {10}^7$
$=2^{\ast }{10}^2$
$=200bits=\frac{200}{8}$
$=25$ bytes