Hi Sue,


Thank you for raising these questions. Below are my answers, tagged <Yimi>:



1) Can composite SR Candidate Paths be limited to be created from only
explicit (aka Static) BGP SR Candidate path?

• If so, how is it done (technically)?

• What text should be found in draft-jiang-idr-sr-policy-composite-path-04
on this limited?

• Is it there?

<Yimi> I think that the current draft does not explicitly address limiting
constituents to explicit BGP paths. In the next revision, the authors meybe
add text to clearly state how to create composite SR Candidate Paths.

2) Is the limitation of composite path to specific BGP sources an
appropriate use of the composite concept from SPRING?

<Yimi> The composite path concept in RFC 9256 is agnostic to the source of
its constituents. I believe that even Limiting constituents to explicit BGP
paths is a valid use case that aligns with SPRING’s goal of providing
flexible policy composition.

3) How does this interact with the PCE composite CPs?

<Yimi> I think that BGP-signaled composite paths and PCE-signaled composite
paths are independent. The draft ensures that BGP extensions do not
interfere with PCE operations, and any conflicts are resolved per RFC 9256.


BR,

Yimi

Susan Hares <[email protected]> 于 2026年7月11日周六 00:11写道:

> Greetings Spring and IDR:
>
>
>
> Please note that IPR may exist for this technology.  If you are
> participating in this discussion and know of IPR, please see the IETF IPR
> rules.
>
>
>
> The authors of draft-jiang-idr-sr-policy-composite-path-04 have requested
> WG LC.  During IETF-125, I spent a lengthy time discussing the issues of
> creating BGP routes from any dynamic source (e.g. IGP).  The authors
> indicated that these BGP composite paths would come from explicit SR Policy
> Candidate Policies, which are statically configured.
>
>
>
> This document’s abstract states:
>
>
>
>    SR Policy Architecture [RFC9256] defines the concept of a Composite
>
>    Candidate Path. A regular SR Policy Candidate Path outputs traffic
>
>    to a set of Segment Lists, while an SR Policy Composite Candidate
>
>    Path outputs traffic recursively to a set of SR Policies on the same
>
>    headend. This document defines extensions to BGP to distribute SR
>
>    policies carrying composite candidate path information. So that
>
>    composite candidate paths can be installed when the SR policy is
>
>    applied.
>
>
>
> The authors have indicated that the source for the composite policy would
> be BGP explicit SR Candidate Paths.
>
>
>
> The SR policy in the composite path can be distributed
>
>    by BGP as described in [RFC9830], by PCEP as described in [RFC
>
>    9862], or through static configuration.
>
>
>
> I have 3 groups of questions as the shepherd for this draft:
>
>
>
> 1) Can composite SR Candidate Paths be limited to be created from only
> explicit (aka Static) BGP SR Candidate path?
>
>    - If so, how is it done (technically)?
>    - What text should be found in
>    draft-jiang-idr-sr-policy-composite-path-04 on this limited?
>    - Is it there?
>
>
>
> 2) Is the limitation of composite path to specific BGP sources an
> appropriate use of the composite concept from SPRING?
>
>
>
> 3) How does this interact with the PCE composite CPs?
>
>
>
> Cheerily, Sue Hares
>
>
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