ALTO Cost Schedule

Document Type Expired Internet-Draft (individual)
Last updated 2014-08-18 (latest revision 2014-02-14)
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The goal of Application-Layer Traffic Optimization (ALTO) is to bridge the gap between network and applications by provisioning network related information. This allows applications to make informed decisions, for example when selecting a target host from a set of candidates. The ALTO problem statement [RFC5693] considers typical applications as file sharing, real-time communication and live streaming peer-to-peer networks. Recently other use cases focused on Content Distribution Networks and Data Centers have emerged. The present draft proposes to extend the cost information provided by the ALTO protocol. The purpose is to broaden the decision possibilities of applications to not only decide 'where' to connect to, but also 'when'. This is useful to applications that have a degree of freedom on when to schedule data transfers, such as non- instantaneous data replication between data centers or service provisioning to end systems with irregular connectivity. The draft therefore specifies a new cost mode, called the "schedule" mode. In this mode the ALTO server offers cost maps that contain path ratings that are valid for a given timeframe (e.g. hourly) for a period of time (e.g. a day). Besides the functional time-shift enhancement providing multi-timeframe cost values, the ALTO Cost Schedule also allows to save a number of ALTO transactions and thus resources on the ALTO server and clients. Last, guidance to schedule application traffic can also efficiently help for load balancing and resources efficiency.


Sabine Randriamasy (
Nico Schwan (

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