I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. Document editors and WG chairs should treat these comments just like any other last call comments. The summary of the review is Ready. This draft specified version 1 of Multipath TCP obsoleting version 0. The paths are identified by the 4-tuple of IP addresses and ports for each path. The services offered to applications are the same as TCP. The additional information needed for setting up and tearing down paths, synchronizing flows, etc., is communicated using TCP options. The Security Considerations section appears to be good and the security mechanisms adequate to achieve the documents goal of being as secure as TCP. There is a good if somewhat generalized Threat Analysis in RFC 6181 as well as an Architecture document in RFC 6182 that considers security aspects. Thanks, Donald =============================== Donald E. Eastlake 3rd +1-508-333-2270 (cell) 1424 Pro Shop Court, Davenport, FL 33896 USA d3e3e3@gmail.com