Extending the Application-Layer Traffic Optimization (ALTO) Protocol

Document Type Expired Internet-Draft (individual)
Authors Enrico Marocco  , Vijay Gurbani 
Last updated 2012-07-30 (latest revision 2012-01-20)
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The Application-Layer Traffic Optimization (ALTO) protocol is designed to allow entities with knowledge about the network infrastructure to export such information to applications that need to choose one or more endpoints to connect to among large sets of logically equivalent ones. The primary use case for the ALTO protocol was peer-to-peer applications for file sharing, video streaming and realtime communications, usually running on end-user devices. However, a number of other applications executing in more controlled environments may also benefit from the information that can be exported through the ALTO protocol. The use cases that have received significant attention include Content Delivery Networks (CDNs), distributed applications running in large datacenters, as well as systems made of inter-communicating ALTO servers. To apply ALTO to these new use cases, this document aims to foster a discussion to determine if, and how, the ALTO protocol could be extended to provide a simple yet useful view of a computational environment that goes beyond the static (or near static) network topology and cost map information.


Enrico Marocco (enrico.marocco@telecomitalia.it)
Vijay Gurbani (vkg@bell-labs.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)