NORTHWESTERN UNIVERSITY

Joint CS/ECE Distinguished Lecture Series in Systems and Architecture

Separating Wheat From Chaff:

On Internet Modeling and Model Validation

Walter Willinger

AT&T Labs - Research

Recent empirical discoveries concerning various scaling properties of the temporal dynamics of Internet traffic or of some of the topological features associated with the physical structure of the Internet have resulted in a number of proposed models or ``explanations'' of these ``emergent'' phenomena.  Many of these explanations invoke concepts such as fractals, chaos, or self-organized criticality, mainly because these concepts are closely associated with scale-invariant phenomena and power laws.  In this talk, I will discuss a simple framework for Internet model validation; that is, identifying those explanations/models that go beyond data fitting, are relevant for the networking application at hand, and can provide a basis for developing a useful, consistent, and verifiable theory of large-scale TCP/IP networks.  In particular, I will discuss why some recently proposed criticality-based models or ``explanations'' from statistical mechanics are specious, at least as far as the networking context is concerned.  (This is joint work with R. Govindan, S. Jamin, V. Paxson, and S. Shenker, Proc. Nat. Acad. Sci. US, Vol. 99, suppl. 1, pp. 2573-2580, 2002.).

Walter Willinger received the Diplom (Dipl. Math.) from the ETH Zurich, Switzerland, and the M.S. and Ph.D. degrees from the School of Operations Research and Industrial Engineering, Cornell University, Ithaca, NY. He is currently a member of the Information and Software Systems Research Center at AT&T Labs-Research, Florham Park, NJ. Before that, he was a Member of Technical Staff at Bellcore (1986-1996). He has been a leader of the work on the self-similar (``fractal'') nature of data network traffic and is co-recipient of the 1996 IEEE W.R.G. Baker Prize Award and the 1994 W.R. Bennett Prize Paper Award from the IEEE Communications Society for the paper titled "On the Self-Similar Nature of Ethernet Traffic". 

Thursday, October 10, 2002 - 4pm - Tech M345

Reception to follow in Tech L324