Media type: E-Article Title: A two‐layer model for improving the energy efficiency of file sharing peer‐to‐peer networks Contributor: Trunfio, Paolo imprint: Wiley, 2015 Published in: Concurrency and Computation: Practice and Experience Language: English DOI: 10.1002/cpe.3213 ISSN: 1532-0626; 1532-0634 Keywords: Computational Theory and Mathematics ; Computer Networks and Communications ; Computer Science Applications ; Theoretical Computer Science ; Software Origination: Footnote: Description: <jats:title>Summary</jats:title><jats:p>As peer‐to‐peer networks gather and share large sets of computing resources, their aggregate energy consumption is an important problem to be addressed, given the economic and environmental impact of energy production and use. This is particularly true for file sharing peer‐to‐peer networks, considered the vast number of nodes participating to these systems. To address such problem, this paper proposes a peer‐to‐peer file sharing model organized in two logical layers. The lower layer is composed of a set of peers providing the files to be shared. The upper layer includes a set of super peers organized to form a distributed hash table, whose purpose is indexing files and peers, including their availability status. Following a sleep‐and‐wake approach, energy saving is achieved by letting peers cyclically switch between normal and sleep modes, where the time passed in normal mode by a peer depends on the number of files it provides. An energy‐saving algorithm and an associated file search and retrieval strategy are proposed within this model. Simulation results show that more than 50% of energy can be saved using the proposed model and that more than 80% of file downloads start with no additional delay compared with a network in which all peers are always powered on. Copyright © 2014 John Wiley & Sons, Ltd.</jats:p>