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Home | Seminars and Symposia | Past seminars/symposia: Wednesday, March 20, 2002

DTC Seminar Series

Changing from Sampled Network Usage


Nick Duffield
AT&T Labs

Wednesday, March 20, 2002
1:30 pm

402 Walter Library

Do usage based charging and traffic sampling mix in the Internet? The sampling process yields inherent discrepancies between estimated and actual usage. For a service provider, its customers will be resistant to overcharging, while its shareholders will be resistant to undercharging. This work shows how non-uniform sampling of traffic flow summaries can be used to minimize sampling variance for a given sample volume. By coupling with a charging scheme that is only sensitive to larger usage, we can explicitly control the error in charging schemes, without statistical assumptions on the traffic flows. If time permits, the method for the dynamic control of the volume of sampled reports will also described. This is joint work with Carsten Lund and Mikkel Thorup.


Dr. Duffield is a Technology Consultant in the Network Mathematics Research Department at AT&T Labs-Research, Florham Park, New Jersey, USA. He holds the B.A. in Natural Sciences (Physics and Theoretical Physics, 1982) and the Certificate of Advanced Study in Mathematics (1983) from the University of Cambridge, U.K. He was awarded the Ph.D. (1987) by London University, U.K., for a study of dynamics and stability of non-equilibrium phase-transitions in biological systems. He held postdoctoral positions in Heidelberg, Germany, and Dublin, Ireland, before joining the faculty of the School of Mathematical Sciences in Dublin City University, Dublin, Ireland in 1991. He moved to AT&T in 1995. Dr. Duffield's home page can be found at