Reducing and Characterizing Packet Loss for High-speed Computer Networks with Real-time Services Reducing and Characterizing Packet Loss for High-speed Computer Networks with Real-time Services a Dissertation Presented by Reducing and Characterizing Packet Loss for High-speed Computer Networks with Real-time Services

Henning G. Schulzrinne Reducing and Characterizing Packet Loss for High-Speed Computer Networks with Real-Time Services May 1993 B.S., Technische Hochschule Darmstadt (Federal Republic of Germany) M.S., University of Cincinnati Ph.D., University of Massachusetts Directed by: Professor James F. Kurose Higher bandwidths in computer networks have made application with real-time constraints, such as control, command, and interactive voice and video communication feasible. We describe two congestion control mechanisms that utilize properties of real-time applications. First, many real-time applications, such as voice and video, can tolerate some loss due to signal redundancy. We propose and analyze a congestion control algorithm that aims to discard packets if they stand little chance of reaching their destination in time as early on their path as possible. Dropping late and almost-late packets improves the likelihood that other packets will make their deadline. Secondly, in real-time systems with xed deadlines, no improvement in performance is gained by arriving before the deadline. Thus, packets that are late and have many hops to travel are given priority over those with time to spare and close to their destination by introducing a hop-laxity priority measure. Simulation results show marked improvements in loss performance. The implementation of the algorithm