Two nodes and B $)$ use sliding$-$window protocol with a $3-$bit sequence number. The

ARQ mechanism, Go$-$Back$-$N is used with a window size of $5.$ Assuming A is transmitting

and $B$ is receiving, show the window positions for the following succession of events.

a$.$ Before A sends any frame.

b$.$ After A sends frames $0,1,2,3$ and B acknowledges $0,2$ and the ACK are received by

A$.$

c$.$ After A sends frames $4,5,6,7$ and B acknowledges $6$ and the ACK is received by A$.$

d$.$ After A sends frames $0,1$ and $B$ acknowledges $1$ and the ACK is received by A$.$