Abstract

The ALTO (Application Layer-Traffic Optimization) Protocol ([RFC7285]) defines several services that return various metrics describing the costs between network endpoints. For example, when downloading a file that is mirrored on several sites, a user application may use these ALTO cost metrics to determine the most efficient mirror site. An ALTO Server may offer a variety of cost metrics, based on latency, bandwidth, hop count, jitter, or whatever else the ALTO Server deems useful. When selecting a mirror site, a client may consider more than one metric, perhaps trading bandwidth for latency. While the base ALTO Protocol allows a client to use more than one cost metric, to do so, the client must request each metric separately. This document defines a new service that allows a client to retrieve several cost metrics with one request, which is considerably more efficient. In addition, this document extends the ALTO constraint tests to allow a user to specify an arbitrary logical combination of tests on several cost metrics.

Authors

Sabine Randriamasy (Sabine.Randriamasy@alcatel-lucent.com)
Wendy Roome (w.roome@alcatel-lucent.com)
Nico Schwan (nico.schwan@thalesgroup.com)

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