VirtualLength: a new packet scheduling algorithm for proportional delay differentiation

One of the important issues in building differentiated services is how to support relative differentiated queueing delay services for packets from different classes. This paper presents a new packet scheduling algorithm, called virtual-length, to address this issue. It provides effective control over the relative average queueing delay ratio between two classes of traffic by monitoring their average arrival rates and cumulative queue lengths. The packets of different classes are forwarded according to their weighted queue lengths with respect to predefined proportional delay parameters. The simulation results show that virtualLength is capable of providing controllable and predictable services for classes with different load distributions under various load conditions. In particular, it can provide more accurate control over classes of traffic in short timescales than other packet scheduling algorithms, and comparable service in long timescales. The results also show that the performance of virtualLength is independent of the distributions of packet arrivals and sizes.