A client host sends a W $=800-$byte file to a server which is L $=1200$ km away over a

B $=2\mathrm{.}5$ Gb$/$s optical fibre network.

$($i$)$ Calculate the upper bound of the link efficiency $($

LEUB

$)$ for this transmission

assuming that the speed of light in optical fibre is c $=200,000$ km$/$s$.$

$($ii$)$ What would be the

LEUB

for a link with transmission speed B $=2\mathrm{.}5$ Mb$/$s$?$

Explain why the results for the calculated values of

LEUB

in parts $($i$)$ and $($ii$)$ are

different.

$($iii$)$ Calculate the necessary size of the file W which will allow to achieve a $50\%$

LEUB

for a link you considered in part $($i$)$