Dr. Vahdat is giving two talks on Friday, April 12. This file gives abstracts of both. His biography follows. This talk will be given at 11am in Education 226. ---------------------------------------------- Title: Performance versus Cost Tradeoffs in Adaptive and Scalable Overlay Networks Speaker: Amin Vahdat Abstract: Currently, there is increasing interest for building large-scale overlays to efficiently deliver data to a large number of simultaneous receivers. Example applications include multimedia distribution, event notification, and update propagation among wide-area replicas. Current approaches for building overlays largely fall into two categories. The first employs probing of network characteristics to build overlays that conform to changing characteristics of the underlying network. These approaches typically assume global knowledge of participants and thus cannot scale. The second approach builds multicast distribution trees on top of a peer to peer infrastructure. Such virtualized overlays, including Tapestry, Chord, CAN, and Pastry, demonstrate remarkable scalability but do not provide any control over the performance characteristics of the resulting tree because of the randomized nature of the protocols. This talk explores whether it is possible to bridge the gap between these two extremes. That is, can we build overlays that both scale and match the characteristics of the underlying network? More specifically, the goal of this work is to build a degree-constrained, low-cost overlay that meets target performance characteristics. Cost may be any measure of the desirability of using a particular link, such as prevailing congestion, the actual amount paid to an ISP, etc. Performance can also be arbitrarily defined, including bandwidth, delay and loss rate. Building the lowest cost tree that satisfies end-to-end performance guarantees (other than for bandwidth) is an NP-complete problem. Thus, our challenge is to build a distributed and scalable system that closely approximates the global optimum under a variety of conditions. We discuss our experience with achieving this goal through the implementation and evaluation of an ACDC (Adaptive Cost, Delay Constrained) overlay. -- This talk will be given at 2:00 pm in MGB 101. ---------------------------------------------------------------- Title: Back to the Future: The Coming Age of Utility Computing Speaker: Amin Vahdat, Duke University Abstract: This talk provides an overview of recent trends in compute environments, including peer-to-peer systems, high performance web services, the computational grid, wireless LANs, and content distribution networks. These trends point to a future where computation and data is increasingly pushed out into the wide area network, placed and replicated on demand to achieve target levels of performance and availability. Future compute devices are likely to be simple caches of "truth" stored somewhere in the network. Computation and storage will be managed and delivered much like the electric utility delivers power: universal compatibility with any compute device that plugs into the wall (or takes advantage of increasingly ubiquitous wireless coverage). Of course, we have seen this vision before. This talk outlines why the time is right for building and deploying a computing utility and a number of the challenges that must be addressed to realize this vision. ------------------------------------------------------------------ Dr. Amin Vahdat is an assistant professor in the department of Computer Science at Duke University. He obtained his Ph.D. in Computer Science in 1998 and his B.S. in Electrical Engineering and Computer Science in 1992, both from the University of California, Berkeley. His research Interests are in the areas of Distributed Systems, Computer Networks, Operating Systems, Mobile/Wireless Systems. In June 2000 he received an NSF career award.