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. This draft aims to provide clear definitions for Active and Passive performance assessment as well as defining Hybrid methods and establishing means of evaluating new methods as they emerge. The document relies heavily on textual references to other specifications, which can at times be a bit tedious for the reader but I have no particular suggestions regarding this point and it's probably fine for a document that is aiming to corral various earlier concepts. The referenced security and privacy considerations were very good (if nearly as long as this spec itself). One minor point, section 4.2 might be better placed before the current section 4.1 to better set-up the ASCII art in section 4.1.