Proportional delay differentiation employing the CBQ service discipline

The DiffServ architecture provides a scalable mechanism for QoS introduction in a TCP/IP network. The idea of DiffServ is based on the aggregation of traffic flows at an ingress (or egress) point of a network and the IP packet marking for different priority flows, according to several classification criteria. Two approaches exist in the DiffServ architecture: the absolute and the relative. In absolute DiffServ, an admission control scheme is used to provide QoS guarantees as absolute bounds of specific QoS parameters. The relative DiffServ model provides QoS guarantees per class expressed with reference to guarantees given to the other classes defined. Our study targets at providing relative proportional delay differentiation service based on class based queue (CBQ) scheduler. The main idea is to frequently adjust the service rates allocated to classes of a CBQ scheduler in order to achieve relative delay spacing among classes. The simulation experiments conducted show that our model can attain relative delay, provided that the required delay differentiation parameters (DDPs) are feasible.