i$.$ Discuss the key difference between random$-$access protocols and controlled$-$access

protocols. State two examples for each type, excluding any ALOHA protocols. $(3$ marks$)$

ii$.$ Determine the vulnerable periods and throughputs for both the pure Aloha network and the

slotted Aloha network, given a frame size of $10$ Kbits $,$ a data rate of $1$ Mbps $,$ the average

number of frames $($G$)$ generated by the system during one frame transmission time is $0\mathrm{.}6.$

Which Aloha protocol demonstrates superior efficiency? Justify your answer. $(4$ marks$)$

iii. The diagram in Fig. $1$ depicts the internal network of ABC Ltd$.$

Switch S$1$ has an entry: the MAC address of PC$-$A & the respective port number.

Assume arbitrary values for the full$-$length MAC addresses for the respective PCs$.$

a$.$ Illustrate the structure of an Ethernet frame, including the necessary values for each

field, for an ICMP echo$-$request, which originates from PC$-$A towards PC$-$B$.(2$ marks$)$

b$.$ Discuss the operational tasks performed by S$1$ during the switching process for ICMP

request. Construct the CAM table in S$1$ stepwise. $(2$ marks$)$

c$.$ Illustrate the structure of an Ethernet frame, including the necessary values for each

field for the ICMP echo$-$reply for the case i$.$e$.$ mentioned in $\text{'}a\text{'}.(1$ mark$)$

d$.$ Discuss the operational tasks performed by S$1$ during the switching process for ICMP

echo$-$request. Construct the CAM table in S$1$ stepwise. $(2$ marks$)$