A probabilistic priority scheduling discipline for multi-service networks

This paper proposes a novel scheduling discipline for service differentiation among traffic classes in multi-service networks, which is referred to as the Probabilistic Priority (PP) discipline. The PP discipline is based on the Strict Priority (SP) discipline with the difference that each priority queue is assigned a parameter as in Weighted Fair Queueing (WFQ) and Weighted Round Robin (WRR) disciplines. The parameter determines the probability with which its corresponding queue is served when it is polled by the server. Similar to WFQ and WRR, service differentiation as well as fairness among traffic classes can be achieved in PP by setting the assigned parameters properly. In addition, the PP discipline can be easily reduced to the ordinary SP discipline or to the reverse SP discipline. Moreover, the PP discipline can provide service segregation among groups of traffic classes while at the same time provide service differentiation among classes within each group. The proposed PP discipline may be used in controlling per-hop behavior in differentiated services networks. (C) 2002 Elsevier Science B.V. All rights reserved.