A differentiated services architecture for multimedia streaming in next generation Internet

This paper presents a Di€erentiated Services (Di€serv or DS) architecture for multimedia streaming applications. Speci®cally, we de®ne two types of services in the context of Assured Forwarding (AF) per hop behavior (PHB) that are di€erentiated in terms of reliability of packet delivery: the High Reliable (HR) service and the Less Assured (LA) service. We propose a novel node mechanism called Selective Pushout with Random Early Detection (SPRED) that is capable of simultaneously achieving the following four objectives: (1) a core router does not maintain any state information for each ̄ow (i.e., core-stateless); (2) the packet sequence within each ̄ow is not re-ordered at a node; (3) packets from HR service are delivered more reliably than packets from LA service at a node during congestion; and (4) packets from TCP trac are dropped randomly to avoid global synchronization during congestion. We show that SPRED is a generalized bu€er management algorithm of both tail-dropping and Random Early Detection (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 Di€serv architecture have substantial performance improvement over the current Best E€ort (BE) Internet architecture for multimedia streaming applications. Ó 2000 Elsevier Science B.V. All rights reserved.