Fountains vs Torrents: The P2P ToroVerde Protocol

In this paper we present ToroVerde, a novel push-based peer-to-peer (P2P) content distribution application exploiting the digital fountain concept through the use of rateless codes. We provide the protocol specification, then describe the simulator and the complete prototype we have developed for Planetlab deployment and testing. To this end, we consider flash crowd and steady arrival patterns as well as highly churning systems to perform a preliminary analysis of the potential advantages of introducing rateless codes. We present results from PlanetLab experiments compared against performance of BitTorrent, that is widely considered as the reference system for content distribution. We also present a few simulation results showing the behavior of ToroVerde as the number of peers in the systems increases. Our results suggest that ToroVerde has the potential of reducing the average download time for small-to-medium sized files in overlays composed of a few hundred peers with a small increase of the communication overhead.