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 peer-to-peer (P2P) applications used traditionally for file-sharing, and more recently for real-time communications and live media streaming. Such applications discover a route 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 measurements, 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 summarize and compare existing approaches, identify open research issues and argue for the need of layer cooperation as a solution to the ALTO problem.