Re: [spring] Comments on draft-ietf-spring-segment-routing-policy (ver 03)

Przemyslaw Krol <> Wed, 24 July 2019 18:23 UTC

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From: Przemyslaw Krol <>
Date: Wed, 24 Jul 2019 14:23:01 -0400
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To: Vishnu Pavan Beeram <>
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Subject: Re: [spring] Comments on draft-ietf-spring-segment-routing-policy (ver 03)
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Hi Vishnu,

Clarification question, if I may.
Are you envisioning weights to be normalized for all sub-candidate-paths
(regardless of the candidate-path they belong to), or rather propose to
have a 2-level split:
- weight for candidate-path grouping specific sub-candidate-paths defining
"global" share of traffic, in comparison with other candidate-paths
- weight for specific sub-candidate-path defining "local" share of the
traffic within specific candidate-path, in comparison with other
sub-candidate-paths in that particular candidate-path


On Wed, Jul 24, 2019 at 6:42 AM Vishnu Pavan Beeram <> wrote:

> Authors, Hi!
> There are some use-cases where the candidate-path (multipath) needs to be
> constructed in such a way that a part of the multipath (a set of
> segment-lists) uses one set of constraints, while the other part (another
> set of segment-lists) uses another set of constraints. Consider the
> scenario where the traffic needs to be steered onto a policy in such a way
> that a specified portion of it uses paths that traverse only blue links
> while the rest uses paths that traverse only red links.
> The current semantics of a candidate-path as defined in Section 2.2 of
> version 3 preclude such use-cases. It should be possible to let the
> semantics be a tad more flexible than they currently are and cater to the
> above scenario (and the likes of it).
> There are a few different ways of addressing this, but I would like to
> propose one that seems least disruptive.
> In addition to the currently specified semantics:
> -- A candidate path may comprise of a set of sub-candidate paths where
> each each sub-candidate path is either dynamic or explicit. The
> sub-candidate path is the unit of signaling of an SR policy between a
> headend and a controller..
> Regards,
> -Pavan
> _______________________________________________
> spring mailing list

Przemyslaw "PK" Krol |  Strategic Network Engineer ing |