Subject: [spring] Éric Vyncke's Abstain on draft-ietf-spring-sr-yang-29: (with COMMENT)

From: Éric Vyncke via Datatracker <[email-masked]>
Date: Thu, 14 Jan 2021 05:45:53 -0800

Éric Vyncke has entered the following ballot position for
draft-ietf-spring-sr-yang-29: Abstain

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COMMENT:
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Thank you for the work put into this document even if I am balloting ABSTAIN,
this is useful piece and it should really be improved to fix my ABSTAIN reasons
so that I could actively support it. Read my ABSTAIN ballot as "I oppose this
document but understand that others differ and am not going to stand in the way
of the others" per https://www.ietf.org/standards/process/iesg-ballots/ .

Please note that I am neither a YANG expert nor a segment routing one (hence my
ABSTAIN rather than a DISCUSS).

Based on title, I was expecting this document to be generic and to see
companion YANG models for the MPLS and IPv6 data planes but it seems that this
document also augments *only* the MPLS one. The asymmetry does not look good to
me... Are the authors/WG sure that the IPv6 YANG model can also be specified by
augmenting this model (draft-ietf-spring-srv6-yang-00 is still a -00 ...) and
relying on types defined in ietf-segment-routing-common ? Especially when
noting that the authors are different ?

The YANG model for SR is really short (mostly meaningless except for one more
tag in the namespace tree):
   "module: ietf-segment-routing
     augment /rt:routing:
       +--rw segment-routing"

To be honest, I strongly dislike the fact that there is no common element
between the YANG modules for MPLS and IPv6 data planes inside
ietf-segment-routing. I admit that I am not an SR expert but I would have
expected more common elements: policies, routing protocols, SID, link bundles,
... even if the leaves could be instantiated as generic types to be augmented
later.

One additional regret is that the document shepherd write-up is really really
short. But it includes the most important element (to my eyes): the WG feedback
& consensus.

Regards,

-éric

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From: "Acee Lindem (acee)" <[email-masked]>
Date: Fri, 15 Jan 2021 15:05:43 +0000

HI Eric, 

See inline.

On 1/14/21, 8:46 AM, "Éric Vyncke via Datatracker" <[email-masked]> wrote:

Yingzhen and I have had several meetings with the SRv6 YANG model editors and are confident that there is alignment. 

There are many ways to factor the IETF YANG models and this one includes the base segment routing support. It seems you are not in touch with the other routing and segment routing models. For example, the routing protocol segment routing extensions are augmentations to the routing protocol models (in alignment with the vendor implementations). 

Thanks,
Acee

    Regards,

    -éric