On scheduling real-time traffic under controlled load service in an integrated services Internet

Abstract

The controlled load service defined within the IETF's Integrated Services architecture for QoS in the Internet requires source points to regulate the traffic while the network provides a soft guarantee on performance. Packets sent in violation of the traffic are marked so that the network may give them lower priority. We have defined the requirements of a scheduler serving packets belonging to the controlled load service. Besides efficiency and throughput goals, we define another important requirement to bound the additional delay of unmarked packets caused due to the transmission of marked packets. For any given desired bound /spl alpha/ on this additional delay, we present the CL(/spl alpha/) scheduler which achieves the bound while also achieving a per-packet work complexity of O(1). We also provide analytical proofs of these results on the CL(/spl alpha/) scheduler. The principle used in this algorithm can also be used to schedule flows with multilevel priorities, such as in some real-time video streams as well as in other emerging service models of the Internet that mark packets to identify drop precedences.