A distributed bootstrapping protocol for overlay networks

Abstract

Peer to peer overlay networks have become popular due to their inherent scalability and resilience properties that come naturally from their decentralized nature. Unfortunately, despite this decentralized approach there is still one important piece that remains centralized: a set of servers to provide identifiers to peers joining the system. This initial step is necessary as new peers need to obtain some contact points in order to establish links to them and join the overlay. This puts out of the protocol model a crucial mechanism as it introduces an external centralized entity to manage the process, leading to problems of scale and fault-tolerance. In scenarios where the churn rate is considerable, the cost of maintaining the list of known peers by the well-known servers may be unbearable. Furthermore, if the peer identifiers provided are not evenly distributed across the universe, this will inevitably cluster the overlay, making it more prone to partitions. In this paper we propose a fully decentralized protocol to obtain those set of initial contact peers using the already deployed infrastructure. By conducting an extensive experimental evaluation we show the effectiveness of the protocol and reason how the ideal number of contact peers may be provided in a fully decentralized fashion.