Optimal admission control for high speed networks:: A dynamic programming approach

We consider in this paper the problem of Call Admission Control of guaranteed performance (GP) connections (such as the CBR and VBR traffic classes in ATM) in the presence of best effort (BE) connections that use the bandwidth left over by the guaranteed performance connections. We assume that the BE sessions do not require a minimum cell rate (MCR) and are thus not subject to call admission control. By slightly increasing rejection rate of GP sessions one may decrease dramatically the delay of BE sessions. We formulate the admission problem as a Markov decision problem and obtain the optimal policy. In particular, we show that it is of a switching curve type. We then compare numerically the performance of the optimal policy to threshold policies as well as to the policy which ignores the BE traffic (and accepts GP sessions as long as there is available bandwidth for them). We show that threshold policies are good approximations for the overall optimal policy.