[spring] draft-ietf-spring-srv6-policy-sid-list-opt-00

[spring] draft-ietf-spring-srv6-policy-sid-list-opt-00 - comments

Gyan Mishra <hayabusagsm@gmail.com> Thu, 02 July 2026 19:23 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Thu, 02 Jul 2026 15:20:47 -0400
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To: draft-ietf-spring-srv6-policy-sid-list-opt@ietf.org, SPRING WG <spring@ietf.org>, IDR List <idr@ietf.org>
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Subject: [spring] draft-ietf-spring-srv6-policy-sid-list-opt-00 - comments
Archived-At: <https://mailarchive.ietf.org/arch/msg/spring/Bu-wpMMoMq_wVTljkFiczPON690>

Dear authors

I would like to comment on this draft as it relates to the optimize draft
under WG Adoption call in IDR.

1. draft-lin-idr-sr-policy-admin-flag-05.txt

2. draft-liu-idr-sr-segment-list-optimize-06.txt-> this draft only relates
to the Spring draft discussion below

3. draft-ali-idr-bgp-ls-sr-policy-sl-opt-distribution-00.txt

This Spring discussion is related to the SRv6 endpoint SID and if it is
ever needed and if it is not needed based on what I have stated below, then
there is no need to adopt the optimize draft.

The additional drafts under adoption call discuss flag to be used to
determine when an endpoint Sid should be used or not.

My thoughts on this topic for SRv6 full Sid and SRV6 Compression both Next
Sid and Replace SID endpoint behaviors that as SRv6 uses the IPv6 data
plane for LPM hop by hop routing the traffic is LPM routed to the SR policy
endpoint no matter what without the endpoint Sid present.

This allows the path to have all SRv6 capable nodes and IPv6 only nodes
along the path.   The SR policy two tuple {color, endpoint} that the
endpoint of the SR policy of the TE steered path along which traffic is
steered is always to the same  prefix node Sid endpoint as defined on the
SR headend node SR policy.  Also if the computed Sid list does not end with
endpoint node Sid the traffic can still IPv6 LPM route to the egress PE
endpoint of the SR policy without ever the need for the endpoint node Sid.

Even for SRv6-MPLS interworking draft use case for endpoint node Sid as the
SRv6 tunnel carrying the MPLS payload can still LPM IPv6 route to the
egress PE without an endpoint SID present.

https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-mpls-interworking-02

There is absolutely no need for an endpoint node Sid for static or dynamic
computed paths due SRv6 using native IPv6 data plane for hop by hop IPv6
LPM routing used for per hop steering.

This would help with consistency across the board with static or dynamic
SID list that the optimization is always enabled and the endpoint sid is
always excluded.  As well as service sid is always excluded.

This consistent compression helps tremendously in steering as it saves 1-2
entries in hops of steering with Next SID giving a total 6 hops without
SRH.  Also helps replace Sid and full Sid to have less entries in the SRH.

I would like to address this with the authors which will help in making a
decision on IDR adoption of the optimize draft.

Kind Regards

Gyan

[spring] draft-ietf-spring-srv6-policy-sid-list-o… Gyan Mishra