Resilience of structured P2P systems under churn: The reachable component method

Abstract

Users in a peer-to-peer (P2P) system join and leave the network in a continuous manner. Understanding the resilience properties of P2P systems under high rate of node churn becomes important. In this work, we first find that a lifetime-based dynamic churn model for a P2P network that has reached stationarity is reducible to a uniform node failure model. This is a simple yet powerful result that bridges the gap between the complex dynamic churn models and the more tractable uniform failure model. We further develop the reachable component method and derive the routing performance of a wide-range of structured P2P systems under varying rates of churn. We find that the de Bruijn graph based routing systems offer excellent resilience under extremely high rate of node turnovers, followed by a group of routing systems that include CAN, Kademlia, Chord and randomized-Chord. We show that our theoretical predictions agree well with large-scale simulation results. We finish by suggesting methods to further improve the routing performance of dynamic P2P systems in the presence of churn and failures.