I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. The document presents a mechanism for servers and clients to conduct synchronization protocols over multiple paths. I didn't see anything wrong with the mechanism, but I am worried that its security benefits are overstated: independent paths may only be partially independent, and attackers can easily migrate from one router to another in most networks. Sincerely, Watson Ladd