Packet Discard Schemes for Differentiated Services Networks with ATM Switching Systems

In this paper two packet discard schemes are proposed with the goal to provide incoming data flows different levels of quality of service. In particular, the assured forwarding in the Differentiated Services per-hop-behavior, as reported in the Request For Comments 2597, is considered as reference scenario. The different levels of quality of service imply different portions of bandwidth assigned to data flows which share that same output link. Good performance in terms of throughput and fairness in bandwidth sharing among equal priority flows are also considered as the requirements to meet. The proposed schemes are also evaluated when end-to-end transport protocols, such as TCP, are employed so as to give some informations about their impact on applications. These dropping schemes are shown to provide good results and to represent a relatively low complex solution for dealing with the most demanding data flows during congestion intervals. Numerical results are reported and discussed for homogeneous and non homogeneous data sources.