A proactive mechanism for quality of service control in high speed networks

The internet offers best effort service only. The problem of providing Quality of Service (QoS) control to multimedia flows in a congested router is challenging in this scenario. A novel Active Queue Management (AQM) mechanism is proposed for use at the router. The design and modelling of this queue-based AQM is presented. The buffer at the outgoing link is a simple First-In-First-Out, shared by packets belonging to n flows. A packet-dropping scheme with a single threshold is applied. As against Random Early Detection (RED), which uses the average queue size to control dropping, this work uses instantaneous queue size for making the decisions. This improves the buffer utilisation at the IP routers. The mechanism helps multimedia applications by giving preferential treatment to their flows. The mechanism also considers inter-protocol fairness by reducing loss rates of Transmission Control Protocol (TCP) flows. By doing this, the scheme implements the fair queuing policy. The scheme is stateless and easy to implement. Simulation results indicate that the new service model gives a better than best-effort treatment to the flows that require good QoS.