Last Call Review of draft-ietf-ippm-twamp-time-format-04
review-ietf-ippm-twamp-time-format-04-secdir-lc-lonvick-2017-03-15-00

Hi,

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 is ready with minor nits. The document calls for the change 
of designation of a field in an established protocol. This is called out 
throughout Section 2 and will need to be ratified by the IANA in Section 
3. The previous documents set the bit to MUST BE ZERO and this document 
uses it to signal an option to use either the NTP timestamp (still using 
0) or a more recently adopted 1588 timestamp (1). The Security 
Considerations section appropriately names the prior documents and 
references their Security Considerations sections.

Minor nits:

The last sentence of the first paragraph of Section 1 is:
"And of mentioned solutions will be subject to additional queuing delays 
that negatively affect data plane clock accuracy."
Perhaps should be "Any of the mentioned..."

The second sentence of the first paragraph of Section 2 is:
"In these procedures, the Modes field been used to identify and select 
specific communication capabilities."
Perhaps should be "...has been used..."

I didn't do a thorough read through the document so there may be other 
minor nits.

Regards,
Chris