> On Jun 1, 2023, at 06:54, Peter Psenak <[email protected]> wrote: > > Hi Antoine, > > thanks for the review, please see my response inline: > > > On 01/06/2023 11:22, Antoine Fressancourt via Datatracker wrote: >> Reviewer: Antoine Fressancourt >> Review result: Ready >> I have reviewed this document as part of the INT area directorate's ongoing >> effort to review all IETF documents being processed by the IESG. >> The document, in version 12, is well written. The objectives of the draft are >> clearly stated, and relate to the requirement stated in RFC 9350 to describe >> in >> specific document each extension of Flex-Algorithm beyond SR-MPLS and SRv6 >> data-planes. The draft's structure is borrowed from RFC 9350 and describes >> forwarding or operational considerations. >> In my view, the document is ready to be published. I only have one minor >> comment that the author might ignore as it may stem from my inexperience with >> IGP Flex Algorithms. As far as I can tell, the metrics that can be used in >> flexalgo can be rather dynamic. Given this dynamicity, what is the policy >> that >> should be adopted in case the metric for a given prefix is updated very >> frequently? IGP convergence can take time, and consumes resources on the >> routers, and I was wondering if there would be some sort of threshold or >> minimum time before an update is considered. > > there are three metric types defined in the draft: > > 1) IGP metric > 2) TE metric > 3) Min Unidirectional Link Delay > > First two are static values configured by administrator. > Third one could be measured, but the min delay mostly reflects the property > of the physical layer and should be semi-constant, unless the physical path > changes (e.g. re-routing at the optical layer). > > RFC8570 that defines the "Min Unidirectional Link Delay" says: > > "Minimum and maximum delay MUST each be derived in one of the > following ways: by taking the lowest and/or highest measured value > over a measurement interval or by making use of a filter or other > technique to obtain a reasonable representation of a minimum value > and a maximum value representative of the interval, with compensation > for outliers." > > RFC8570 also talks about announcement periodicity and announcement > suppression to avoid frequent changes in these values. > > On top of what RFC8570 mentions, IGP implementations have SPF throttling > mechanisms to avoid too many calculations, even if some originator advertises > these values too frequently.
For example, see https://datatracker.ietf.org/doc/rfc8405/ Thanks, Acee > > thanks, > Peter > > >> Nits from the Gen-ART review have been addressed in version 12.
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