A robust PI controller for improving performance in the AF-based differentiated services network

The assured forwarding (AF) based service in a differentiated services (Diffserv) network fails to provide bandwidth assurance to aggregates in some circumstances. Several intelligent marking mechanisms have been proposed in the literature to improve bandwidth assurance for aggregates using the knowledge gathered at the ingress nodes. In this paper, we apply a control theoretic approach to this problem. We design a nonlinear proportional-integral (NPI) controller, called NPI-ACT, for adapting the CIR threshold. Performance results using extensive simulations demonstrate significant improvement using NPI-ACT in achieving bandwidth assurance over a wide range of network conditions compared to earlier mechanisms proposed in the literature.