In packet$-$switched networks, the source host partitions long application$-$layer

messages into smaller segments and sends them into the network. The receiver then reassembles the

segments back into the original messages. We refer to this process as message segmentation and

reassembly. Consider a message of $8{10}^6$ bits that is to be sent from source to destination passing

through two packet switches. Suppose each link of the routers is $2Mbps.$ At this low transmission

rate, transmission delay dominates other delay components. We can ignore propagation, queuing,

and processino delave

$2.$a Consider sending the message from source to destination without message segmentation. How

long does it take to move the message from the source host to the first packet switch? What is

the total time to move the message from source host to destination host?

$2.$b Now suppose that the message is segmented into $800$ packets, with each packet being $10,000$

bits long. How long does it take to move the first packet from source host to the first switch?

When the first packet is being sent from the first switch to the second switch, the second

packet is sent from the source host to the first switch. At what time will the second packet be

fully received at the first switch?

$2.$c How long does it take to move the file from source host to destination host when message

segmentation is used? Compare this result with your answer in part $($a$)$ and comment.

$2.$d In addition to reducing delay, what are reasons to use message segmentation?

$2.$e Discuss the drawbacks of message segmentation.