$3.[1\mathrm{.}25$ marks$]$

$($i$)[0\mathrm{.}5]$ Consider the data transfer between two hosts $\backslash ($ A $\backslash )$ and $\backslash ($ B $\backslash ),$ with the stop$-$and$-$wait protocol, rdt$3\mathrm{.}0.\backslash ($ A $\backslash )$ is located on the West Coast of the United States and $\backslash ($ B $\backslash )$ is located on the East Coast. The speed$-$of$-$light round trip propagation delay between $\backslash ($ A $\backslash )$ and $\backslash ($ B$,$ R T T $\backslash ),$ is approximately $30$ milliseconds. Suppose that $\backslash ($ A $\backslash )$ and $\backslash ($ B $\backslash )$ are connected by a channel with a transmission rate, $\backslash ($ R $\backslash ),$ of $1$ Gbps $.$ Given the packet size, $\backslash ($ L $\backslash ),$ of $1500$ bytes, determine the channel utilization.

$($ii$)[0\mathrm{.}5]$ Following the problem $($i$),$ consider the pipelined technique instead of stop$-$and$-$wait protocol. How big would the window size have to be for the channel utilization to be greater than $\backslash (98\backslash \%\backslash )?$

$($iii$)[0\mathrm{.}25]$ What does the receive window $($rwnd$)$ field in a TCP segment indicate?