A Differentiated Services architecture for multimedia traffic in IP networks

This paper presents a Differentiated Services (DS) architecture to support multimedia streaming applications. We define service differentiation in terms of reliability of packet delivery. More specifically, two types of services are defined: the High Reliable (HR) service and the Less Assured (LA) service. We propose a novel node mechanism called Selective Pushout with Random Early Detection (or SPRED) that is capable of simultaneously achieving the following three objectives: (1) The packet sequence within each application is preserved at the node; (2) Packets from HR service are delivered more reliably than packets from LA service at a node during congestion; and (3) Packets from TCP traffic are dropped randomly to avoid global synchronization during congestion. We show that SPRED is a generalized buffer management algorithm of both tail-dropping and RED, and combines the best features of pushout (PO), RED and RED with In/Out (RIO) mechanisms. Simulation results demonstrate that under the same link speed and network topology, network nodes employing our DS architecture have substantial performance improvement over the current BE Internet architecture for multimedia streaming applications.