Absence of Evidence as Evidence of Absence: A Simple Mechanism for Scalable P2P Search

We propose a novel search mechanism for unstructured p2p networks, and show that it is both scalable, i.e., it leads to a bounded query traffic load per peer as the peer population grows, and reliable, i.e., it successfully locates all files that are (sufficiently often) brought into the system. To the best of our knowledge, this is the first time that a search mechanism for unstructured p2p networks has been shown to be both scalable and reliable. We provide both a formal analysis and a numerical case study to illustrate this result. Our analysis is based on a random graph model for the overlay graph topology and uses a mean-field approximation to characterize the evolution of how files are replicated in the network.