Peer-to-Peer Infrastructure: A Survey of Research on the Application-Layer Traffic Optimization Problem and the Need for Layer Cooperation

A significant part of the Internet traffic today is generated by perr-to-peer (P2P) applications used traditionally for file-sharing, and more recently for real-time communications and live media streaming. Such applications discover a routet to each other through an overlay network with little knowledge of the underlying network topology. As a result, they may choose peers based on information deduced from empirical measure- ments, which can lead to suboptimal choices. We refer to this as the Application Layer Traffic Optimization (ALTO) problem and present a survey of existing literature. We summerize and compare existing approaches, identify open research issues and argue for the need of layer cooperation as a solution to the ALTO problem. Finally, we examine the role of the Internet Engineering Task Force (IETF) in standardizing specific protocols related to this problem.