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. 

Ready with Nits - this draft adds the ability to use PTP timestamps as an alternative to NTP timestamps for active performance measurement protocols OWAMP and TWAMP.  Although this draft does a good job of discussing interoperability for both sides of the session having or not having support for this operational capability, in several places it states that if a send/receiver support this capability it must be set to 1 in the flags.  However, only for TWAMP Light mode, this seems configurable.  This may just be my interpretation, but it probably should state that local implementations MAY provide a configurable knob to not negotiate PTPv2 timestamps in section 2.1 and 2.2 even if the capability is supported by the implementation.