$($a$)$ Explain how an Ethernet local area network $($LAN$)$ uses contention

to share a network between users.

$($b$)$ A signal propagates at $8s\frac{ec}{km}$ on an Ethernet LAN cable

segment length that is $500$ metres long. The transmission rate is

$10$Mbit$\frac{s}{sec}$ and the length of the frames is between $72$ bytes and

$1526$ bytes. Estimate the maximum utilisation and the data

throughput in the cases where there are:

$($i$)2$ active stations;

$($ii$)200$ active stations

$($c$)$ Discuss the steps needed to make this Ethernet LAN operate

successfully over a length of $3700$ metres.