SUBJECT $1(30\%)$ Answer in detail the following questions selecting only $4$ out of the $8$ of them according to the following schedule

taking into account your STUDENT$$S EXAM ID associated numbers.

$1)$ Take the MAXIMUM number out of the $5$ numbers your student exam ID has been transformed into, let$$s say MAXIMUM

number $=14($transformed from the letter N or n of the Latin alphabet$).$ Divide this MAXIMUM number by $8$ and take the

remainder, which is $6$

$2)$ With numbering of the questions q$0,$q$1,$q$2,$q$3,$q$4,$q$5,$q$6,$q$7$ the above student with remainder $=6$ will start from the question$=$q$6$

and cyclically will choose $4$ questions, the following: q$6,$q$7,$q$0,$q$1$ and so forth.

q$0.$ Consider an application that transmits data at a steady rate $($for example, the sender generates an N$-$bit unit of data every k time

units, where k is small and fixed$).$ Also, when such an application starts, it will continue running for a relatively long period of time.

Answer the following questions, briefly justifying your answer:

a$.$ Would a packet$-$switched network or a circuit$-$switched network be more appropriate for this application? Why?

b$.$ Suppose that a packet$-$switched network is used and the only traffic in this network comes from such applications as described above.

Furthermore, assume that the sum of the application data rates is less than the capacities of each and every link. Is some form of

congestion control needed? Why?

ANSWER

a$)$ A packet switch network is more suitable since small fixed packets transmitted over a long period can be served through packet

switching without the need to fully occupy a bandwidth for long time as in circuit switching

b$)$ No$,$ under these conditions the traffic can be afforded. There is no need for congestion control..

q$1.$ Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending

host and the switch and between the switch and the receiving host are R$1$ and R$2,$ respectively. Assuming that the switch uses store$-$

and$-$forward packet switching, what is the total end$-$to$-$end delay to send a packet of length L$?($Ignore queuing, propagation delay,

and processing delay.$).$ What happens in the case of not having store and forward packet switching capacity as well as not having

queuing capacity.

q$2.$ What advantage does a circuit$-$switched network have over a packet$-$switched network? What advantages does TDM have over

FDM in a circuit$-$switched network? List the differences between Message switching compared to circuit and packet switching.