Analysis and dimensioning of credit-based flow control for the ABR service in ATM networks

ATM networks have shown to reveal difficulties in simultaneously guaranteeing the requested quality-of-service while efficiently utilizing all the available bandwidth for economic reasons. The ABR (available bit rate) service class was designed to fill the gap of bandwidth with less delay but loss sensitive traffic. Due to the bursty nature of higher-priority traffic and the resulting bandwidth fluctuations a flow control is required for ABR that avoids buffer overflow and cell loss. These demands can both only be supported by credit-based flow control. It offers immediate access to the full link bandwidth without a ramp-up time. However, though its behaviour is deterministic an analysis by queueing models is impossible. In this paper we treat stability, performance and dimensioning issues of a representative class of credit-based flow control protocols with a new stochastic Petri-net model. We use its formalism to prove its stability and study the utilization performance in all operation regions with it. This implies the proposed dimensioning of buffer sizes and parameters, which is an important task during connection admission