Queue Management and QoS Routing for Traffic Differentiation

This paper presents a simulation study of router mechanisms to provide differentiated levels of service to traffic with diverse performance requirements in IP networks. The paper focuses on queue management mechanisms and on Quality of Service routing. The performance of the Random Early detection dropper associated with the Weighted Round Robin scheduling discipline is compared with the Dynamic Degradation Distribution system. This system redistributes the resources among traffic classes according to the state of the route. Afterwards, the impact of Quality of Service routing in networks where there is class-based traffic differentiation is assessed. The results show that even though the queue management mechanisms actually deployed in commercial routers naturally support traffic differentiation and provide adequate levels of QoS, the Dynamic Degradation Distribution system is able to give better performance in situations of congestion. Moreover, the inclusion of Quality of Service routing capabilities clearly improves traffic performance and network utilization.