Consistency maintenance in dynamic peer-to-peer overlay networks

In this paper, we present techniques to maintain temporal consistency of replicated objects in data-centric peer-to-peer overlay applications. We consider both structured and unstructured overlay networks, represented by Chord and Gnutella, respectively, and present techniques for maintaining consistency of replicated data objects in the presence of dynamic joins and leaves. We present extensions to the Chord and Gnutella protocol to incorporate our consistency techniques and implement our extensions to Gnutella into a Gtk-Gnutella prototype. An experimental evaluation of our techniques shows that: (i) a push-based approach achieves near-perfect fidelity in a stable overlay network, (ii) a hybrid approach based on push and pull achieves high fidelity in highly dynamic overlay networks and (iii) the run-time overheads of our techniques are small, making them a practical choice for overlay networks.