A Hierarchical Packet Scheduler for Differentiated Services in High-Speed Networks

In this paper, we propose a multi-level hierarchical dynamic deficit round-robin (MLHDDRR) scheduling algorithm enhanced from the existing dynamic deficit round-robin (DDRR) for the support of differentiated services. The level of service differentiation can be changed simply by adjusting parameters. The MLHDDRR scheduler can deliver small delays for short packets of each class. This feature can achieve great delay improvement in comparison with the waiting time priority (WTP) scheduler and is of great importance for improving the QoS of some real-time applications. Moreover, the MLHDDRR scheduler can efficiently provide much better QoS for real-time applications under high link utilizations (95%-99%). Because MLHDDRR is enhanced from DDRR, it is intended to be implemented in high-speed switch systems to deliver short delay and high throughput for the increasing volume of real-time video and audio communication. Extensive simulation results are presented to show the effectiveness of the MLHDDRR scheduler