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 the IETF last call and IESG review, and sometimes on special request. The purpose of the review is to assist the Routing ADs. For more information about the Routing Directorate, please see https://wiki.ietf.org/en/group/rtg/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-mpls-msd-yang-07
Reviewer: Dhruv Dhody
Review Date: 2024-06-03
IETF LC End Date: 2024-06-04
Intended Status: Proposed Standard

## Summary:

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

## Comment:

* This draft defines 2 YANG models one is IANA-maintained to mirror the msd-type registry and the other is augmenting base MPLS to include MSD values. 

### Major Issues:

- Please remove the BCP14 boilerplate (Section 1.1) as you are not using any of those keywords. Also, remove from the ietf-mpls-msd YANG model.

- You should explicitly state that this is an initial version of "iana-msd-types" YANG model - "This document defines the initial version of the IANA-maintained 'iana-msd-types' YANG module." 

### Minor Issues:

- Title: Please change to "A YANG Data Model for MPLS Maximum Segment Identifier (SID) Depth (MSD)". Also, update the reference in the YANG model around RFC XXXX.

- The abstract suggests that only one YANG model is defined in this I-D. Consider rephrasing or adding some hints about the IANA model as well. 

- Section 1, "YANG [RFC7950] is a data definition language.."; I suggest changing it to data modeling as that is the term used in the referenced RFC. 

- Section 1, I am unsure about the text "The augmentation defined in this document requires support..."; isn't it obvious that one needs to support the model one is augmenting...

- Section 4, please add this text in the description inside the YANG module - "This YANG module is maintained by IANA and reflects the 'IGP MSD-Types' registry."

- identity msd-erld, should also have a reference to RFC9088. 

- In "ietf-mpls-msd", please remove the reference "RFC XXXX: A YANG Data Model for MPLS MSD." immediately after the module description. The revision statement is the correct place to have this reference. 

- leaf msd-value should also include text for "0 represents the lack of ability to support a SID stack of any depth". 

- I can not parse "A type of Node MSD is the smallest same type link MSD supported by the node.";"

- RFC8340 should be normatively referenced. 

### Nits:

- s/(MSD) Types as the IANA the IGP MSD-Types registry/(MSD) Types as per the IANA IGP MSD-Types registry/

- s/which itself augments [RFC8349]/which itself augments routing RIB data model [RFC8349]/

- s/IANA maintained module/IANA-maintained module/

- s/This module will be maintained by IANA if more MSD types are added to the registry./This module will be maintained by IANA and updated if and when there is any change in the registry./

- s/and it is to provide support of different types of MSDs in MPLS data plane./and it provides support for different types of MSDs in the MPLS data plane./

- s/read-only data decided by/read-only data as per/

- Section 4, expand SID on first use in the YANG model. 

Thanks,
Dhruv