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Engineering Peer-to-Peer Systems

Prof. Henning Schulzrinne, Columbia University


While there have been hundreds of papers on peer-to-peer systems, most deployments have been proprietary and single-purpose, with research exceptions such as OpenDHT. The Internet Engineering Task Force is exploring standardizing a common peer-to-peer protocol that can serve applications from VoIP to media delivery. There is a significant difference between a protocol used for a single purpose or a research prototype, to creating a protocol that can serve unforeseen applications, be used on a global scale and be managed. As peer-to- peer protocols transition from papers to standards, it is also important to consider when they are the most appropriate solution and when other approaches are more helpful. I will discuss how resource usage, energy consumption and reliability may not always favor p2p approaches.


Prof. Henning Schulzrinne received his Ph.D. from the University of Massachusetts in Amherst, Massachusetts. He was a member of technical staff at AT&T Bell Laboratories, Murray Hill and an associate department head at GMD-Fokus (Berlin), before joining the Computer Science and Electrical Engineering departments at Columbia University, New York. He is currently chair of the Department of Computer Science. Protocols co-developed by him, such as RTP, RTSP and SIP, are now Internet standards, used by almost all Internet telephony and multimedia applications. His research interests include Internet multimedia systems, ubiquitous computing, mobile systems, quality of service, and performance evaluation. He is a Fellow of the IEEE.

An Oportunity for ISP and P2P Collaboration

Prof. Anja Feldmann, Ph.D., Deutsche Telekom Laboratories, TU Berlin


Peer-to-peer (P2P) systems offer astounding possibilities to their users. As such P2P users are a good source of revenue for the Internet Service Providers (ISPs). But the immense volume of P2P traffic also poses a significant challenges to the ISPs. P2P systems have to either build their overlay topologies agnostic of the underlay topology or measure the path performance themself. Accordingly, routing in P2P systems is often suboptimal and largely independent of the Internet routing. In addition, the ISP looses control of its traffic. This situation is disadvantageous for both: the ISPs and the P2P users. To overcome this, we suggest that ISPs and P2P systems collaborate. We propose and evaluate the feasibility of a solution where the ISP offers an ``oracle'' to the P2P users. When the P2P user supplies the oracle with a list of possible P2P nodes, the oracle ranks them according to certain criteria, like their proximity to the user or higher bandwidth links. This can be used by the P2P user to choose appropriate neighbors, and therefore improve its performance. The ISP can use this mechanism to better manage the immense P2P traffic, e.g., to keep it inside its network, or to direct it along a desired path.


Anja Feldmann is a professor at Deutsche Telekom Laboratories a unit of Deutsche Telekom and an Institut of the Technische Universitaet Berlin, Germany. From 2000 to 2006 she headed the network architectures group first at Saarland University and then at TU Muenchen. Before that (1995 to 1999) she was a member of the Networking and Distributed Systems Center at AT&T Labs - Research in Florham Park, New Jersey. She received a M.S. degree in Computer Science from the University of Paderborn, Paderborn, Germany, in 1990 and M.S. and Ph.D. degrees in Computer Science from Carnegie Mellon University in Pittsburgh, USA, in 1991 and 1995, respectively. Her current research interests include understanding the current Internet and its applications for the purpose of performance debugging and intrusion prevention as well as new network architectures.

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