Consider figure $1,$ where the sender transmits one packet of size L $=1$ KB

$($kilobytes$).$ The link speeds are R$1=$ R$2=$ R$3=1$ Mbps $($megabits per second$).$ The length of each link is

$100$ Km$.$ Compute the end$-$to$-$end delay for the following situations. We assume that the propagation

speed of the packet is $20,000$ Km$/$s$,$ and that the processing time of the packet at each router is $5$s$.$Suppose two hosts, A and B$,$ are separated by $20,000$ kilometers, and are connected by a direct link of $R=$

$5Mbps.$ Suppose the propagation speed over the link is $2\mathrm{.}5*{10}^8$ meters $\frac{?}{sec}.$

a$)$ Calculate the bandwidth$-$delay product $R*d_{\text{p}\text{r}\text{o}\text{p}}.$

b$)$ Consider sending a file of $800,000$ bits from Host A to Host B$.$ Suppose the file is sent continuously

as one large message. What is the maximum number of bits that will be in the link at any given time?

c$)$ Provide an interpretation of the bandwidth$-$delay product.

d$)$ What is the width $($in meters$)$ of a bit in the link? Is it longer than a football field?

e$)$ Derive a general expression for the width of a bit in terms of the propagation speed $s,$ the transmission

rate $R,$ and the length of the link $m.$