Non-priority QoS guarantee for next generation routers

Abstract

Virtual Output Queuing (VOQ) is a proffered queuing strategy that solves the head of line blocking (HoL) issue in routers implementing input queuing (IQ). Also, VOQ can achieve 100% throughput with an effective scheduler. However, most schedulers for VOQ are deterministic algorithms, which either provide QoS guarantee or do not. Even though these algorithms have high performance, they schedule packets arbitrarily or with priority thereby starving some traffic. These algorithms may become inadequate in future networks where data rate continues to increase and traffic with different QoS requirements co-exist. This paper recommends a probabilistic QoS guarantee for routers using VOQ. Probabilistic QoS guarantees for network traffic ensure fairness and prevent traffic starvation. A probabilistic scheduling algorithm termed Iterative Probabilistic Scheduling (IPS) is proposed. IPS guarantees probabilistic QoS with a basic mathematical operation as its scheduling policy. From simulation, it achieves a high throughput performance and does not starve traffic. IPS was used at the first stage of the Multi-stage Queuing and Scheduling (MQAS) architecture. MQAS is a two-stage queuing architecture with VOQ at the input and Output Queuing (OQ) at the output of the router.