Dynamic bandwidth allocation to virtual paths in ATM networks

An important problem associated with ATM networks is to determine the bandwidths that should be allocated to the set of virtual paths in the network. The over-allocation of bandwidth to the virtual paths has a strong adverse impact on network throughput, signalling and call blocking QoS. There exist many algorithms in the literature which attempt to assign bandwidth to the virtual paths in real time or in an off-line fashion. However, to the best of the authors' knowledge, no work takes into consideration the adverse impact of over allocation of network bandwidth to the virtual paths. In this paper we discuss various trade-offs such as throughput, signalling and QoS and show that there exists a set of bandwidths beyond which the performance of the network deteriorates rapidly with respect to all three measures. Furthermore, it is shown that this upper bound can be computed distributively in real time using run time estimates. We use this result in designing a dynamic bandwidth allocation algorithm. This dynamic algorithm provides the flexibility of adjusting QoS, network throughput and the signalling load on the switches, to the levels desired by the network designer, in real time.