FIFO queueing is simple but does not protect traffic from flows that send more than their share or flows that fail to use end-to-end congestion control. At the other extreme, per-flow scheduling mechanisms provide max-min fairness but are more complex, keeping state for all flows going through the router. This paper proposes RED-PD (RED with Preferential Dropping), a flow-based mechanism that combines simplicity and protection by keeping state for just the high-bandwidth flows. RED-PD uses the packet drop history at the router to detect high-bandwidth flows in times of congestion and preferentially drop packets from these flows. This paper discusses the design decisions underlying RED-PD, and presents simulations evaluating RED-PD in a range of environments.

Abstract—We discuss a new packet service paradigm, called ’Less Impact Better Service ’ (LIBS), which is realized through a novel queuing discipline, called ’Non-Congestive Queuing ’ (NCQ). NCQ prioritizes small packets when conditions permit, and utilizes service thresholds to confine the delay impact of prioritization on congestive applications. We show that LIBS and NCQ satisfy more users with diverse demands on delay and throughput. We obtained both analytical and simulation results, which are very promising. Diversity is simulated by using FTP, sensor and VoIP traffic. Index Terms—Service Differentiation, Packet Scheduling, QoS 1