The EGOIST Overlay Routing System

A foundational issue underlying many overlay net- work applications ranging from routing to peer-to-peer file sharing is that of connectivity management, i.e., folding new arrivals into an existing overlay, and re- wiring to cope with changing network conditions. Pre- vious work has considered the problem from two per- spectives: devising practical heuristics for specific appli- cations designed to work well in real deployments, and providing abstractions for the underlying problem that are analytically tractable, especially via game-theoretic analysis. In this paper, we unify these two thrusts by us- ing insights gleaned from novel, realistic theoretic mod- els in the design of Egoist - a distributed overlay rout- ing system that we implemented, deployed, and evalu- ated on PlanetLab. Using extensive measurements of paths between nodes, we demonstrate that Egoist's neighbor selection primitives significantly outperform existing heuristics on a variety of performance metrics, including delay, available bandwidth, and node utiliza- tion. Moreover, we demonstrate that Egoist is com- petitive with an optimal, but unscalable full-mesh ap- proach, remains highly effective under significant churn, is robust to cheating, and incurs minimal overhead. Fi- nally, we use a multiplayer peer-to-peer game to demon- strate the value of Egoist to end-user applications. This technical report supersedes BUCS-TR-2007-013.