This document has been reviewed as part of the transport area review team's ongoing effort to review key IETF documents. These comments were written primarily for the transport area directors, but are copied to the document's authors and WG to allow them to address any issues raised and also to the IETF discussion list for information. When done at the time of IETF Last Call, the authors should consider this review as part of the last-call comments they receive. Please always CC tsv-art@ietf.org if you reply to or forward this review. The draft reads well and is essentially ready to go from a transport perspective. One question that arises is why these three quite distinct mechanisms fixing different parts of the RFC 7252 are compiled into a single document. Efficiency, yes, but otherwise, they don't seem to have much in common. p9, 2nd para, line 5: may -> MAY ? A question out of curiosity: in section 3.4, could a client easily exhaust server resources if just sent many blocks and changed the Request-Tag on each of them? Should sections 3.6 and 3.7 move to an appendix? They discuss design alternatives. Nits: "can not" -> "cannot" The last sentence in the second to last paragraph of section 1.1 has nested brackets, which may or may not be intentional.