A robust protocol for building superpeer overlay topologies

The concept of superpeer has been introduced to improve the performance of popular file-sharing applications. A superpeer is a node in a P2P network that operates as a server for a set of clients, and as an equal w.r.t. other superpeers. By exploiting heterogeneity, the superpeer paradigm allows P2P networks to run more efficiently, without compromising their decentralized nature. This paper describes SG-1, a novel generic mechanism for the construction and the maintenance of overlay topologies based on superpeers. SG-1 is based on the well-known gossip paradigm, with nodes exchanging information with randomly selected peers and re-arranging the topology according to the requirements of the particular P2P application. The resulting protocol is extremely efficient and robust, capable to deal with a continuous flow of nodes joining and leaving the system, as well as to repair a network where up to 100% of the existing super-peers have been removed.