Chapter 1, Problem P15P

Explanation of Solution

Assume the traffic intensity in a router as $\text{I}\text{=}\frac{\text{La}}{\text{R}}$

The expression used for calculating the transmission time of each packet in terms of size of packet (L) and rate of link (R) is $\frac{\text{L}}{\text{R}}$  seconds.

The queuing delay in terms of traffic intensity (I) is $\frac{\text{IL}}{\text{R}\text{(1}\text{-}\text{I)}}$

The total delay is $\frac{\text{IL}}{\text{R}\text{(1}\text{-}\text{I)}}\text{+}\frac{\text{L}}{\text{R}}\text{=}\frac{\text{IL}\text{+}\text{L}\text{(1}\text{-}\text{I)}}{\text{R(1}\text{-}\text{I)}}\text{=}\frac{\text{L}}{\text{R(1}\text{-}\text{I)}}$