Napster and Gnutella: a Comparison of two Popular Peer-to-Peer Protocols

This article presents the reverse engineered protocols of two popular peer-to-peer models, Napster and Gnutella. Napster presents a model where a central broker handles discovery and coordination of files among peers, but the exchange of files takes place between the peers. Gnutella removes the centralization and extends the model further by requiring the peers to contribute to the coordination and discovery efforts. Napster is a very scalable model but its resiliency is reduced since discovery and coordination are centralized. In contrast Gnutella is resilient since there are no centralized components, but it is not scalable since the structure of Gnutella produces a large number of messages. A system is scalable if the load on the system increases at a linear rate with an increase in users. A system is resilient if it is able to function correctly after one or more component failures. An alternative peer-to-peer solution using the scalability of Napster and the resiliency of Gnutella is presented at the end of this work.