Providing flow-based proportional differentiated services in class-based DiffServ routers

DiffServ provides class-based differentiated quality of service (QoS). For perception of users, flow-based service differentiation is much more important than class-based. Class-based QoS per-hop behaviour (PHB) is ensured in a DiffServ router. However, a flow in a higher class may get worse QoS than a flow in a lower class due to unbalanced traffic conditions. Therefore, a novel scheme with a Bloom-filter-based estimator for number of active flows, a dynamic weighted fair queueing (WFQ) scheduler, and a queue management mechanism to provide flow-based proportional QoS differentiation is proposed. This scheme dynamically adapts the WFQ weight of each class according to estimations of numbers of active flows in each class to provide proportional bandwidth differentiation for flows in different classes. Furthermore, a queue management mechanism with estimation of numbers of active flows and queue length feedback control is employed to control the queue length of each class around a target value to achieve delay differentiation. Through detailed simulations, the proposed scheme is shown to be able to provide flow-based proportional bandwidth and delay differentiations for flows in different classes at the same time.