Application-Layer Traffic Optimization (ALTO) Problem Statement

Abstract

Distributed applications --such as file sharing, real-time communication, and live and on-demand media streaming --prevalent on the Internet use a significant amount of network resources. Such applications often transfer large amounts of data through connections established between nodes distributed across the Internet with little knowledge of the underlying network topology. Some applications are so designed that they choose a random subset of peers from a larger set with which to exchange data. Absent any topology information guiding such choices, or acting on suboptimal or local information obtained from measurements and statistics, these applications often make less than desirable choices.This document discusses issues related to an information-sharing service that enables applications to perform better-than-random peer selection.

Application-Layer Traffic Optimization (ALTO) Server Discovery

“…In the ALTO use cases that have been described in the ALTO problem statement [RFC5693] and/or discussed in the ALTO working group, the ALTO server's URI as such has always been considered as public information that does not need protection of confidentiality.…”

“…In the ALTO use cases that have been described in the ALTO problem statement [RFC5693] and/or discussed in the ALTO working group, this scenario has not been identified as a relevant threat.…”

“…A high-level discussion of security issues related to ALTO is part of the ALTO problem statement [RFC5693]. A classification of unwanted information disclosure risks, as well as specific security-related requirements can be found in the ALTO requirements document [RFC6708].…”

“…The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource [RFC5693]. ALTO is realized by a client-server protocol; see requirement AR-1 in [RFC6708].…”

Application-Layer Traffic Optimization (ALTO) Protocol

“…This document defines the ALTO Protocol, which provides a solution for the problem stated in [RFC5693]. Specifically, in today's networks, network information such as network topologies, link availability, routing policies, and path costs are hidden from the application layer, and many applications benefited from such hiding of network complexity.…”