Friendships that Last: Peer Lifespan and its Role in P2P Protocols

Abstract

We consider the problem of choosing who to befriend among a collection of known peers in distributed P2P systems. In particular, our work explores a number of P2P protocols that, by considering peers lifespan distribution a key attribute, can yield systems with performance characteristics more resilient to the natural instability of their environments. This article presents results from our initial efforts, focusing on currently deployed decentralized P2P systems. We measure the observed lifespan of more than 500,000 peers in a popular P2P system for over a week and propose a functional form that fits the distribution well. We consider a number of P2P protocols based on this distribution, and use a trace-driven simulator to compare them against alternative protocols for decentralized and unstructured or loosely-structured P2P systems. We find that simple lifespan-based protocols can reduce the ratio of connection breakdowns and their associated costs by over 42%.