ALTO H1/H2 Protocol

Many Internet applications are used to access resources, such as pieces of information or server processes, which are available in several equivalent replicas on different hosts. This includes, but is not limited to, peer-to-peer file sharing applications. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications, which have to select one or several hosts from a set of candidates, that are able to provide a desired resource. This memo proposes one possible way of implementing the ALTO protocol, called H1H2. The H1H2 protocol is a client/server protocols between end hosts and ALTO servers that allows two different ways of exchanging data between the server and the client.