Subject: [spring] RtgDir Review: draft-ietf-spring-sr-yang-28

From: Tal Mizrahi <[email-masked]>
Date: Tue, 8 Dec 2020 13:52:08 +0200

Hello,

I have been selected as the Routing Directorate reviewer for this
draft. The Routing Directorate seeks to review all routing or
routing-related drafts as they pass through IETF last call and IESG
review, and sometimes on special request. The purpose of the review is
to provide assistance to the Routing ADs. For more information about
the Routing Directorate, please see
http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir

Although these comments are primarily for the use of the Routing ADs,
it would be helpful if you could consider them along with any other
IETF Last Call comments that you receive, and strive to resolve them
through discussion or by updating the draft.

Document: draft-ietf-spring-sr-yang-28
Reviewer: Tal Mizrahi
Review Date: 08-Dec-2020
Intended Status: Standards Track

Summary:
I have some minor concerns about this document that I think should be
resolved before publication.

Comments:
The document defines a YANG data model for MPLS segment routing. The
document is in good shape, and I believe it is almost ready for
publication.

My comments are mainly about the need for a clear definition of the
scope of the document. While these comments do not require major
changes in the document, a bit of rephrasing and clarifying text will
go a long way here.

Issues:
- The document is focused on SR-MPLS, while RFC8402 discusses both
SR-MPLS and SRv6. I am sure there is a good reason for this, but it is
important to point out at the very beginning of the document that it
does not cover SRv6 and preferably also the reason for this.
- It is important to clarify the scope of the YANG models in the
introduction: do they refer only to SR routers, or also to SR
ingress/egress nodes?
- The Common Types module is mentioned for the first time in Section
8. It would be appropriate to mention it and describe its purpose in
Section 3.
- In the following text it would be more accurate to replace: "with
Segment Routing (SR)." ==> "with MPLS Segment Routing (SR)."

         "This augments routing data model (RFC 8349)
          with Segment Routing (SR).";

---

From: Yingzhen Qu <[email-masked]>
Date: Tue, 8 Dec 2020 12:13:39 -0800

Hi Tal,

Thank you for your review and comments, we have published version -29 to
address your comments. Please see my detailed answers below inline.

Thanks,
Yingzhen

> does not cover SRv6 and preferably also the reason for this.

 [Yingzhen]: yes, this document focuses on the SR-MPLS data plane. However
there is ietf-segment-routing.yang module defined as the generic frame,
which is meant to be augmented by different data planes, including both
SR-MPLS and SRv6. This was the consensus between the authors of this draft
and authors of SRv6 YANG model. If you think the abstract and introduction
is not clear, please let us know.

> introduction: do they refer only to SR routers, or also to SR

[Yingzhen]:  for ingress/egress nodes, do you mean SR policy? which is
defined in a separate draft:
https://tools.ietf.org/html/draft-raza-spring-sr-policy-yang-03

> 8. It would be appropriate to mention it and describe its purpose in

[Yingzhen]: Good suggestion. I added a small paragraph for the common yang
module.

> [Yingzhen]: fixed.

---

From: Tal Mizrahi <[email-masked]>
Date: Wed, 9 Dec 2020 08:02:38 +0200

Hi Yingzhen,

Thanks for the quick response.

Please see below.

>  [Yingzhen]: yes, this document focuses on the SR-MPLS data plane. However there is ietf-segment-routing.yang module defined as the generic frame, which is meant to be augmented by different data planes, including both SR-MPLS and SRv6. This was the consensus between the authors of this draft and authors of SRv6 YANG model. If you think the abstract and introduction is not clear, please let us know.

Right. I believe this point should be clarified in the introduction
with an informative reference to the SRv6 YANG draft.

> [Yingzhen]:  for ingress/egress nodes, do you mean SR policy? which is defined in a separate draft: https://tools.ietf.org/html/draft-raza-spring-sr-policy-yang-03

Right, again I suggest to clarify this point in the draft.

Cheers,
Tal.

On Tue, Dec 8, 2020 at 10:13 PM Yingzhen Qu <[email-masked]> wrote:
>
> Hi Tal,
>
> Thank you for your review and comments, we have published version -29 to address your comments. Please see my detailed answers below inline.
>
> Thanks,
> Yingzhen
>
> On Tue, Dec 8, 2020 at 3:52 AM Tal Mizrahi <[email-masked]> wrote:
>>
>> Hello,
>>
>  [Yingzhen]: yes, this document focuses on the SR-MPLS data plane. However there is ietf-segment-routing.yang module defined as the generic frame, which is meant to be augmented by different data planes, including both SR-MPLS and SRv6. This was the consensus between the authors of this draft and authors of SRv6 YANG model. If you think the abstract and introduction is not clear, please let us know.
>
>>
> [Yingzhen]:  for ingress/egress nodes, do you mean SR policy? which is defined in a separate draft: https://tools.ietf.org/html/draft-raza-spring-sr-policy-yang-03
>
>>
> [Yingzhen]: Good suggestion. I added a small paragraph for the common yang module.
>
>>

---

From: Yingzhen Qu <[email-masked]>
Date: Mon, 21 Dec 2020 17:39:33 +0000

Hi Tal,

Sorry for the late response. We had a discussion among the authors, and we agree that we'll add a claim that SRv6 is not supported in this document, but we don't want to add informational references to other drafts that's augmenting the base SR module since this is not controlled by the base module. 

If you don't mind, we'll add the claim in the next version together with other review comments. Please let us know if you have any other comments.

Thanks,
Yingzhen

On 12/8/20, 10:02 PM, "Tal Mizrahi" <[email-masked]> wrote:

    Hi Yingzhen,

    Please see below.

    > [Yingzhen]:  for ingress/egress nodes, do you mean SR policy? which is defined in a separate draft: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-raza-spring-sr-policy-yang-03&amp;data=04%7C01%7Cyingzhen.qu%40futurewei.com%7C1a975630ea744417404c08d89c0812a0%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C1%7C637430905774109043%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=YWASNbjqQcAof5%2BOTbww296DJd2Z%2B7jFyH44ZQQ9GGc%3D&amp;reserved=0

    Cheers,
    Tal.

    On Tue, Dec 8, 2020 at 10:13 PM Yingzhen Qu <[email-masked]> wrote:
    >> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Ftrac.tools.ietf.org%2Farea%2Frtg%2Ftrac%2Fwiki%2FRtgDir&amp;data=04%7C01%7Cyingzhen.qu%40futurewei.com%7C1a975630ea744417404c08d89c0812a0%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C1%7C637430905774109043%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=r1LP0z8f3uvm7jRVXkk20anNxOY2k15ny3%2Fni5aEj1g%3D&amp;reserved=0
    >>
    > [Yingzhen]:  for ingress/egress nodes, do you mean SR policy? which is defined in a separate draft: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-raza-spring-sr-policy-yang-03&amp;data=04%7C01%7Cyingzhen.qu%40futurewei.com%7C1a975630ea744417404c08d89c0812a0%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C1%7C637430905774109043%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=YWASNbjqQcAof5%2BOTbww296DJd2Z%2B7jFyH44ZQQ9GGc%3D&amp;reserved=0
    >
    >>