Performance guarantees in QoS networks are either deterministic or statistical. A deterministic service guarantees that all packets from a flow satisfy given worst-case end-to-end delay bounds and no packets are dropped in the network. A statistical service allows a fraction of traffic to violate its QoS guarantees and can extract additional capacity from a network by exploiting statistical properties of traffic. The 1990s have witnessed a lot of progress on the analysis of networks with deterministic QoS for a variety of scheduling algorithms. The analysis of networks with statistical QoS was found to be more difficult. Using so-called `effective envelopes' which are, with high certainty, upper bounds of multiplexed traffic, we recently showed that many admission control functions which were derived for a deterministic service, can be reused for a statistical service. Having available a toolbox for performing admission control of both deterministic and statistical QoS, we will compare the achievable link utilization for a variety of services, traffic conditioning algorithms, and scheduling algorithms.

This talk presents recent results from joint work with R. Boorstyn, A. Burchard, C. Oottamakorn, S. Patek, and E. Yilmaz.

Short Bio:

Jorg Liebeherr received a Ph.D. degree in Computer Science from Georgia Tech in 1991. In 1992 he was a Postdoctoral fellow at the University of California, Berkeley. From 1992 - 1997 and since 1998, he has been with the Department of Computer Science at the University of Virginia, where he is currently an Associate Professor. From 1997 - 1998 he was an Associate Professor in the Department of Electrical Engineering at Polytechnic University. He currently serves as Editor-in-Chief of IEEE Network, and he serves on the editorial boards of ACM/IEEE Transactions on Networking, Computer Communications (as US Editor), Real-Time Systems Journal, and Cluster Computing.