| Speaker: | Stephan Bohacek, University of Delaware |
|---|---|
| Abstract: | Email worms spread over graphs defined by email address books. In order to study the propagation of email worms, it is necessary to understand the graph over which they spread. The email address book graph and other graphs such as the World Wide Web and Internet routers have received much attention recently. There has been extensive work suggesting that for these graphs, the degree of each node is distributed according to a heavy-tailed distribution. Other work has shown that the World Wide Web and Internet router graph can be decomposed into two basic parts: a highly connected core and lightly connected tendrils. This structure provides insight into worm propagation. This talk will explore these graphs and show how heavy-tailed degree distribution typically leads to a highly connected core. However, we will also see how graphs such as the Internet router graph are not typical. For example, the core is not nearly as connected as the theory leads one to expect. Furthermore, the growth function (the number of nodes visited as a function of the number of "hops" from starting node) is significantly different from that of the typical graph with heavy-tailed degree distribution. Notwithstanding the Internet router graph's peculiarity, to a worm, the Internet graph appears similar to the typical heavy-tailed degree distribution. A slightly different notion of connectivity leads to an explanation for this behavior. |
| Biography: | Stephan Bohacek received his BS in Electrical Engineering and Computer Science from the University of California Berkeley in 1989. From 1989 to 1996, Dr. Bohacek was a digital signal processing engineer for Theta Digital and Wadia Digital. In 1999, he received is Ph.D. in Electrical Engineering - Systems from the University of Southern California. From 1999 to 2002, he was a non-tenure track, assistant professor in the Department of Mathematics at the University of Southern California. Since 2002 he has been an assistant professor at the University of Delaware in the Department of Electrical and Computer Engineering. Dr. Bohacek's research is focused on networking. Recently, his efforts have been directed toward traffic and network modeling, congestion control, routing, networking security and pricing issues. |
| Presented On: | September 20, 2002 |
| Videotape: | <Not available.> |
