$1)$ Consider sending a packet from a source host to a destination host over a fixed route. List the delay components in the end$-$to$-$end delay. Which of these delays are constant and which are variable?

$$

$2)$ Visit the Transmission Versus Propagation Delay interactive animation at the companion Web site $($Transmission versus Propagation Delay Interactive Animation $($pearsoncmg$.$com$)).$ Among the rates, propagation delay, and packet sizes available, find a combination for which the sender finishes transmitting before the first bit of the packet reaches the receiver. Find another combination for which the first bit of the packet reaches the receiver before the sender finishes transmitting.

$$

$3)$ How long does it take a packet of length $1,000$ bytes to propagate over a link of distance $2,500$ km$,$ propagation speed $2\mathrm{.}5108$ m$/$s$,$ and transmission rate $2$ Mbps$?$ More generally, how long does it take a packet of length L to propagate over a link of distance d$,$ propagation speed s$,$ and transmission rate R bps$?$ Does this delay depend on packet length? Does this delay depend on transmission rate?