Q$.$ Two endpoints in a voice$-$over$-$IP session are connected by a path of $4$ optical switches. All links are running

at $1$Gb$//$s and the endpoints are separated by $3000$ km $.$ All packets are of size $1500$ Bytes. Assume the bit

propagation speed is $2$xx$10^(8)$m$//$s$.$ Note that $1$ KB of data is $1024$ Bytes, but $1$Mb$//$s is $10^(6)$bits$//$s$.$

$($a$)$ What is the minimum round trip time $($RTT$),$ assuming there is no queueing delay and assuming processing

time at each host is negligible?

$($b$)$ For this part only, assume that one router on the path has a steady queue occupancy of $5$ packets. What

is the end$-$to$-$end delay $($one way, not round trip$)$ in this case?

$($c$)$ Assume the maximum queue occupancy for every router queues is $5$ packets. What is the maximum

end$-$to$-$end delay?

$($d$)$ For Part $($c$),$ how long should the playback buffer be at the destination voice$-$over$-$IP client be if each

packet arrives successfully, without being dropped? Express your answer in bytes.

$($e$)$ For Part $($c$),$ how long should the playback buffer be at the destination voice$-$over$-$IP client if each packet

either arrives successfully when first transmitted, or is dropped the first time and then arrives successfully

on the second attempt? Assume the sender retransmits a packet only after it finds out that the packet

was dropped, which is after twice the maximum end to end delay. Express your answer in bits.