Implications of Selfish Neighbor Selection in Overlay Networks and Other Problems in the Areas of Content Distribution and Overlay Networks
Speaker: Nikos Laoutaris, Marie Curie Postdoc Fellow, Boston University and University of Athens.
Date: 25 September 2006 Time: 12:00-13:30
Location: "Mediterranean Studies" Seminar Room, FORTH, Heraklion, Crete.
Host: Mema Roussopoulou, Assistant Professor, University of Crete


The first part of my talk will be on the Implications of Selfish Neighbor Selection in Overlay Networks. Following, is a brief description of this work:

"In overlay network for routing or content sharing, each node must select a fixed number of immediate overlay neighbors for routing traffic or requests for content. A selfish node entering such a network would select neighbors so as to minimize the weighted sum of expected access costs to all destinations. Previous work on selfish neighbor selection has built intuition with simple models where edges are undirected, access costs are modelled by hop-counts, and nodes have potentially unbounded degree. In practice however, important side constraints not captured by these models lead to richer games with substantively and fundamentally different outcomes. Our work models neighbor selection as a game involving directed links, constraints on the number of allowed neighbors, and costs reflecting both network latency and node preference. We express a node's (best response) wiring strategy to a directed version of the k-median problem and use this observation to obtain pure Nash equilibria. We study the performance of such wirings analytically and also experimentaly on synthetic topologies as well as on measurements and maps collected from PlanetLab and the AS-level Internet, respectively. Our results indicate that selfish nodes can reap substantial performance benefits when connecting to overlay networks composed of non-selfish nodes. On the other hand, in overlays that are dominated by selfish nodes, the resulting stable wirings are optimized to such great extent, that even non-selfish newcomers can extract near-optimal performance through naive wiring strategies."

The second part of the talk will provide an overview of my research in the areas of content distribution and overlay networks. I will briefly touch upon the following:

-- Distributed Selfish Replication and Caching

-- Distributed Placement of Service Facilities in Large-Scale Networks

-- Storage Capacity Allocation for Content Networks

-- Analytic Modeling of Replacement Algorithms and Application to the Interconnection of Cache Memories

-- The Cache Inference Problem and Its Application to Content and Request Routing

-- Optimization of Playout Schedulers for Packet Video Receivers

I will conclude my talk with a few pointers into on-going and future research on the aforementioned and other related areas.


Nikos Laoutaris is a Marie Curie Outgoing International Post-doctoral Fellow at Boston University and the University of Athens. He received the Ph.D. degree in Computer Science from the Department of Informatics and Telecommunications of the University of Athens, Greece, in 2004, for his work in the area of Content Networking. He also holds an M.Sc. degree in Telecommunications and Computer Networks (2001) and a B.Sc. degree in Computer Science (1998), both from the same department. His main research interests are in the analysis of algorithms and the performance evaluation of Internet content distribution systems (CDN, P2P, web caching), overlay networks, and multimedia streaming applications.

Detailed CV and publications are available at: Nikolaos Laoutaris, Marie Curie Postdoc Fellow Boston University and University of Athens e-mail: nlaout@cs.bu.edu, tel.: (617) 358-2376 web: http://cs-people.bu.edu/nlaout/and he can be contacted on nlaout@cs.bu.edu

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