# GATE Papers >> CSE >> 2015 >> Question No 235

Question No. 235

Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (108 bits per second) over a 1 km (kilometer) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/sec) in the cable?

Solution of Question No 235 of GATE 2015 CSE Paper

Band width = 100 $\times$ 106 bps

d = 1000 m

For CSMA/CD: td $\geq$ 2Pd

$\begin{array}{l}\frac{1250\times8}{100\times10^6}=2\times\frac{1000}{x\;m/s}\\\;\;\;\;\;\;\;\;\;\;\;\;x=\frac{2\times1000\times100\times10^6}{1250\times8}\\\;\;\;\;\;\;\;\;\;\;\;\;\;\;=2\times10^7=20000\;(\mathrm{km}/\sec)\end{array}$