Last Call Review of draft-ietf-ippm-twamp-time-format-05
review-ietf-ippm-twamp-time-format-05-opsdir-lc-mitchell-2017-03-17-00

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.