Suppose Host A sends three segments, $S_n,S_{n+1}$ and $S_{n+2},$ back$-$to$-$back to Host $B$

using a pipelined protocol. Assume that all segments before segment $n$ were

received correctly.

a$.$ If the Selective Repeat protocol is adopted and $S_n$ and $S_{n+2}$ were received

correctly, but $S_{n+1}$ was lost. Before timeout occurs, what would host B do with

$S_{n+2}?$ Which segment would host B Ack before the timeout occurs? Justify your

answers.

b$.$ For GBN and if $S_n$ and $S_{n+1}$ are both lost but $S_{n+2}$ was received correctly, what

would host B do with $S_{n+2}?$ Which segment would it Ack before the timeout

occurs? Justify your answers.

c$.$ For GBN$,$ which segment would host B Ack, if $S_n,S_{n+1}$ and $S_{n+2}$ are all received

correctly.

Draw diagrams for $($a$)$ and $($b$)$ supporting your arguments.

$[5$ points$]$