SIMULATIVE ANALYSIS OF ROUTING AND LINK ALLOCATION STRATEGIES IN ATM NETWORKS SUPPORTING ABR SERVICES

In this paper an ATM call level model, where service classes with QoS guarantees (CBR/VBR) as well as elastic (best effort) services (ABR/UB R) coexist, is proposed and a number of simulations have been carried out on three different network topologies. Elastic traffic gives on th e network level rise to new challenging problems since for a given ela stic connection the bottleneck link determines the available bandwidth and thereby put constraints on bandwidth at other links. Thereby band width allocation at call arrivals but also bandwidth reallocation at c all departure becomes, together with routing, an important issue for i nvestigation. Two series of simulations have been carried out where th ree different routing schemes have been evaluated together with two ba ndwidth allocation algorithms. The results indicate that the choice of routing algorithm is load dependent and in a large range the shortest path algorithm - properly adopted to the mixed CBR/ABR environment - performs very well.