I have reviewed this document as part of the Operational directorate's  ongoing effort to review all IETF documents being processed by the IESG.  These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be included in AD reviews during the IESG review.  Document editors and WG chairs should treat these comments just like any other last call comments. 

Status: Ready with Nits

Overall, I think this is a well written document, that could flow better with minor revisions. The Abstract and the Introduction include the exact same information; I think the document would benefit from having more information in the Introduction section, something that expands upon the current text, or discusses the use case, and why I care.  From time to time I find myself wanting to red line the text, for missing words (like "the") - a style preference perhaps, but flowing english sentences make a document read easier. A lack of discussion on ECT (1) and ECT (0) (Table 1) made this reader stop and google; a bit of conversation here would have been helpful. Last, NITS is mostly clean, but not entirely. I applaud the call out to ongoing work, and Appendix A, but a minor tweak to the doc from Nits output before you send this into the queue would be helpful.

Thanks
Sarah