I am the assigned Gen-ART reviewer for this draft. The General Area Review Team (Gen-ART) reviews all IETF documents being processed by the IESG for the IETF Chair. Please treat these comments just like any other last call comments. For more information, please see the FAQ at . Document: draft-ietf-bess-evpn-bum-procedure-updates-09 Reviewer: Paul Kyzivat Review Date: 2021-09-04 IETF LC End Date: 2021-09-07 IESG Telechat date: ? Summary: This draft has serious issues, described in the review, and needs to be rethought. General: My review of this document is limited because I have no knowledge of the subject domain. Nevertheless I think I was able to grasp the gist of what this document intends to achieve and identify a concern. However it is possible that I have misunderstood and so my comments may be off base. While I have no reason to doubt the mechanisms specified, I think the manner in which they are specified is likely to lead to confusion and misunderstanding by developers. IIUC, RFC7117 improved the handling of BUM traffic for VPLS, but did not address BUM traffic for EVPN. Then RFC7432 specified how to handle BUM traffic for EVPN while referencing RFC7117 for some of its procedures, even though RFC7117 had no provision for support of EVPN. It appears to me that someone who had an implementation of RFC7117 for VPLS might have had to modify it to support RFC7432, yet RFC7432 did not indicate that it updated RFC7117. The developer would have had to infer what changes were required. But at least the changes seem to be small and unlikely to be misunderstood. The current document specifies in its heading and abstract that it updates RFC7432, while not mentioning RFC7117. Yet section 2 says: ... For brevity, only changes/additions to relevant [RFC7117] and [RFC7524] procedures are specified, instead of repeating the entire procedures. From these it is ambiguous whether RFC7117 is or is not being updated. It then goes on to state: Note that these are to be applied to EVPN only, and not updates to [RFC7117] or [RFC7524]. This further clouds things. How could it be known how future updates to those documents might interact with the changes in this document? In the remainder of the document I find no explicit text that appears to normatively updates RFC7432. I find this mystifying. However there are numerous places that normatively change RFC7117. Several of these are of the form: The following bullet in Section N.N.N.N of [RFC7117]: ... is changed to the following when applied to EVPN: ... even though RFC7117 didn't contemplate supporting EVPN at all. This seems to assume that an entirely different implementation of RFC7117 will be made for EVPN and these modifications made to that, while not impacting implementations of RFC7117 being used for other types of VPNs. Is this a reasonable assumption? Overall it seems that it will be very difficult for a developer to read this document and determine exactly what must be implemented, or after the fact to determine whether an implementation conforms to this document. IMO a different style of specification is called for. Probably an RFC7117bis and perhaps a RFC7432bis.