Question $3.)$ Explain step$-$by$-$step all of the RDT $($Reliable Data Transfer$)$ yersions, and, what

improvement that each RDI provides:

Question $4.)$ Consider a packet of length $2,000$ bytes. This packet travels from host $A,$ through a

link with length of $500$ km $,$ a router with queueing delay $2$ ms another link with length of $750$

km $,$ eventually to host B$.$ Here ims stands formiiisecond. One miliisecond is $0\mathrm{.}001$ second.

Suppose the propagation speed on both links is $2\mathrm{.}5108\frac{m}{s},$ the transmission rates of both

links are $10$ Mbps $.$ What is the cotal end$-$to$-$end delaytrom $A$ to $B$ in unit of ms fillisecond$)?$

The derivation procedure is required. Must list all intermediate steps $$e$.$g$.,$ propagation delay.

transmission delay, router processing delay, router queueing delay, etc.$),$ calculation formuta or

equations, and units $($suctr as bytes, bits, km$,$ m$,$ ms$,$ Mbps$,$ bps$,$ ettc$)$