Hi All, With the interim meeting behind us, I was suggested to start the discussion of the multi-domain use case, which is a use case driven by a real setting.
Details: A motivation use case of multi-domain ALTO is the LHCONE setting, which is an L3VPN consisting of multiple networks [1]. Given a set of endpoint nodes N (e.g., remote storage elements), and their connectivity, which is a set E of selected source-destination pairs (s, d) in NxN, we can define a multi-domain cluster as a set of autonomous systems formed by (1) the autonomous systems containing the endpoints; and (2) the autonomous systems on the path for those for an (s, d) in E. Both the transport scheduling system (FTS) and the transport orchestration system (Rucio) can benefit from a network view of a multi-domain cluster. For example, FTS can use the mapping (s, d) -> path to compute the accounting of total traffic volume on a given link; and Rucio can use (s, d) -> path metric to select the source with the lowest distance path, when there are multiple potential sources. The current ALTO protocol is designed more for a single-domain setting, and hence needs extensions to allow the stitching of information from multiple ALTO servers representing the member autonomous systems (AS) in a multi-domain cluster. For example, the source AS can have the global path vector, but it is abstracted to the AS level. Hence, it needs a recursive query process to reconstruct the finer-grain metrics (beyond the AS path metric) of the path from the source to the destination. There can be multiple southbound implementations, e.g., extension to BGP (e.g., flow BGP) and also the extension of the ALTO northbound querying process. It needs also to address the issue of incremental deployment. Hence, a short paragraph describing the problem is: Design ALTO multi-domain queries to compute the aggregated path metrics from a given source to a given destination in a multi-domain cluster. [1] https://twiki.cern.ch/twiki/bin/view/LHCONE/LhcOneMaps
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