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 describes two optional features of the Two-Way Active Measurement Protocol (TWAMP): a. The ability of a controller host to tag packets to allow simplified identification. b. A sender packet format that allows test packets of equal size to be sent each way. The security considerations section does exist and I've followed the references to the One-way Active Measurement Protocol (OWAMP) security considerations section, which TWAMP extends. OWAMP has a nice write-up of the various attacks and how to mitigate such attacks. I don't believe the new TWAMP features discussed in this draft introduces any new vectors beyond what OWAMP/TWAMP already has. General comments: None. Editorial comments: Closing parentheses missing: (by the Server or Session-Reflector Shawn. --