Relying on randomness PlanetLab experiments with distributed file-sharing protocols

In this paper we present and evaluate a fully distributed file-sharing system architecture. Initially, a seeder node splits a large file into moderate-sized chunks and offers it for download. The seeder and all peers interested in downloading the file join a Chord-based overlay and contact each other randomly for chunk transfers. We report and discuss PlanetLab tests on this system as well as on our modified Chord implementation which it is based on. We give an algorithm for finding uniformly random peers in the overlay and another for estimating the distribution of chunk copies. Both algorithms turn out to have a significant effect on the performance, the first one in particular.