Document: draft-ietf-idr-bgp-ct-09
Reviewer: Mohamed Boucadair
Review Date: 28/06/2022
IETF LC End Date: N/A
Intended Status: Experimental Track

I have been selected to do a routing directorate “early” review of this draft.

# General & Meta Comments

Many thanks for the effort put into this document. 

I like the goal and the overall approach that are documented in this draft. The authors included a very comprehensive set of samples to illustrate the overall behavior, in various case. That is really valuable, even if I suspect that some would argue that this material can be moved to an appendix.  

I think that the specification can be better simplified by:

(1) Providing early in the document an reference arch with the various entities.

(2) Adding a NEW section to call out explicitly the intended applicability scope (mainly MPLS, which few SRv6 matters)

(3) Questioning whether all new introduced terms are really needed (BN vs. PE, TN vs. P as examples)

(4) Better focusing on the key extensions and leaving out (for other I-Ds) many parts, claims, and specific applicability. For example, I don't   think that the discussion on intent bring much value to the spec. Also, there are many redundant parts in the spec (with the same behavior called several times or an authoritative RFC is cited by the the behavior text echoed again in the doc).  

(5) Adding a new section to group in one single place  Operational/OAM considerations

As this is an Experimental spec, I expect the document to include a list of intended experiments goals and a set of success criteria. 

Parts of the text are pointing to individual I-Ds to illustrate some specific deployments. I suggest to remove those from the document. It is up to these individual I-Ds to discuss the applicability to CT, not the other way around. 

Please refer to the detailed review for specific items. Don't be surprised by +150 comments. This is a sign that the I enjoyed reading this spec:-)

# Detailed Review:

FWIW, my detailed review can be found at:

* pdf: https://github.com/boucadair/IETF-Drafts-Reviews/blob/master/draft-ietf-idr-bgp-ct-09-rev%20Med.pdf 
* doc: https://github.com/boucadair/IETF-Drafts-Reviews/raw/master/draft-ietf-idr-bgp-ct-09-rev%20Med.doc

Please pick whatever you see useful in the detailed review. Hope this review is useful.