The effects of AQM on the performance of Assured Forwarding Service

Several active queue management (AQM) mechanisms have been proposed in the literature to provide better support for congestion control. However, their performance is examined mainly in best-effort networks. In this paper, we present an empirical study of the effects of AQM mechanisms on the performance of the Assured Forwarding (AF) Service in the non-oversubscribed Differentiated Services networks. The AQM mechanisms to be studied include some existing mechanisms and a new AQM scheme, proposed in this paper. The study is carried out in the cases of the standard traffic conditioner and intelligent traffic conditioners. Extensive simulation results show: (i) when the standard traffic conditioner is employed at the ingress routers, the transient and steady-state behaviors of an AQM scheme in controlling the queue length not only affect the achievement of bandwidth assurance, but also affect the attainment of excessive bandwidth and link throughput; (ii) the behaviors of an AQM affect the ability of an intelligent traffic conditioner in improving bandwidth assurance; (iii) self-tuning AQM schemes perform better than AQMs with fixed-gains in terms of the achievement of bandwidth assurance and link throughput.