$2)$ In the Selective Reject ARQ protocol which uses a window size of

$400,$ the transmitter receives a negative acknowledgment $($REJ$300)$

after it sent frame $400.$ In this case the transmitter must retransmit

frames:

$($a$)300$ to $400$

$($b$)1$ to $400$

$($c$)400$ only $($d$)300$ only

$2$

$($a$)$

$($b$)$

$($c$)$

$($d$)$

$3)$ Assume that two nodes, A and B$,$ are connected via a full duplex

line of $10$ km$.$ Node A transmits frames to node B at a data rate of

$10$ Mbits$/$s$.$ Assume that all the frames have a fixed size of $1000$

bits; and the BER of the line is equal to $10-6.$

The probability of receiving a frame in error depends on:

$($a$)$ data rate

$($c$)$ BER

$($b$)$ distance of the line

$($d$)$ neither a$,$ b or c

$3\mathrm{.}1($a$)$

$($b$)$

$($c$)$

$($d$)$