[alto] Comment on draft-ietf-alto-performance-metric-09

Martin Duke <martin.h.duke@gmail.com> Fri, 17 April 2020 19:45 UTC

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From: Martin Duke <martin.h.duke@gmail.com>
Date: Fri, 17 Apr 2020 12:45:15 -0700
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To: draft-ietf-alto-performance-metrics@ietf.org, IETF ALTO <alto@ietf.org>
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Subject: [alto] Comment on draft-ietf-alto-performance-metric-09
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This is not a full review. I'm late to this and I apologize if I'm covering
ground which has been fully resolved before. With all hats off...

It has come up in the working group before that some of the cost metrics
can vary quite a lot over time, much more quickly than the scale at which
ALTO would update them.

Have we considered changing the metrics to have more long-lived properties
while still being useful? For example
1. we could split the various delay metrics into min and max versions. Min
and Max delay should be relatively constant over a given topology. Max
delay maps quite nicely to something like an SLA.
2. packet loss -- can we focus this on link layer losses rather than queue
drops? Most simply, this could just be a boolean that says "this path
frequently has losses not related to congestion" but could also be expanded
into a link packet error rate, if valuable. Congestion based losses are of
course dependent on the application.

Thanks
Martin