RFC 9439

Application-Layer Traffic Optimization (ALTO) Performance Cost Metrics, August 2023

File formats:

icon for HTML icon for text file icon for v3pdf icon for XML
Also available: XML file for editing
Q. Wu
Y. Yang
Y. Lee
D. Dhody
S. Randriamasy
L. Contreras
alto (ops)

Cite this RFC: TXT  |  XML  |   BibTeX

DOI:  https://doi.org/10.17487/RFC9439

Discuss this RFC: Send questions or comments to the mailing list alto@ietf.org

Other actions: Submit Errata  |  Find IPR Disclosures from the IETF  |  View History of RFC 9439


The cost metric is a basic concept in Application-Layer Traffic Optimization (ALTO), and different applications may use different types of cost metrics. Since the ALTO base protocol (RFC 7285) defines only a single cost metric (namely, the generic "routingcost" metric), if an application wants to issue a cost map or an endpoint cost request in order to identify a resource provider that offers better performance metrics (e.g., lower delay or loss rate), the base protocol does not define the cost metric to be used.

This document addresses this issue by extending the specification to provide a variety of network performance metrics, including network delay, delay variation (a.k.a. jitter), packet loss rate, hop count, and bandwidth.

There are multiple sources (e.g., estimations based on measurements or a Service Level Agreement) available for deriving a performance metric. This document introduces an additional "cost-context" field to the ALTO "cost-type" field to convey the source of a performance metric.

For the definition of Status, see RFC 2026.

For the definition of Stream, see RFC 8729.

Advanced Search