Performance of ABR service over ATM networks with mixed switch types

The ATM Forum has adopted rate-based schemes as the standard congestion control mechanisms for available bit rate (ABR) service. Two types of rate-based schemes are supported by the ATM Forum specification, namely binary feedback and explicit rate feedback. Since the implementation of one of these schemes in ATM switches is left to the switch manufacturers, it is expected to have both types working on the same network. The compatibility of switches each running a different scheme was considered in the ATM Forum specification. However, since each type of switch has its own merits and demerits, the interoperability of these switch types and its impact on the performance of the network deserves extensive studies. This paper looks at the steady state performance of ABR service in networks consisting of both switch types (i.e. heterogeneous networks). In order to find the best locations for each switch type, several cases of switch type locations are considered. Moreover, the impact of ABR sources parameter setting on the performance of heterogeneous networks is studied.