It is clear that if a router gives preferential treatment to one flow or one class of flows, then that flow or class of flows will receive improved service. It is not as clear that the overall service provided by the internet is improved. This question is intended to illustrate an overall improvement. Consider a network with a single link modeled by an exponential server of rate Ts = 1, and consider two classes of flows with Poisson arrival rates of l1 = l2 = 0.25 that have utility functions U1 = 4 - 2 Tq1 and U2 = 4 - Tq2, where Tqi represents the average queueing delay to class i. Thus, class 1 traffic is more sensitive to delay than class 2. Define the total utility of the network as V = U1 + U2.

a. Assume that the two classes are treated alike and that FIFO queueing is used.

What is V?

b. Now assume a strict priority service so that packets from class 1 are always transmitted before packets in class 2. What is V? Comment.