Hello, 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. -- Most pseudowire Emulation Edge-to-Edge (PWE3) encapsulations mandate the use of the Control Word (CW) to carry information essential to the emulation, to inhibit Equal-Cost Multipath (ECMP) behavior, and to discriminate Operations, Administration, and Maintenance (OAM) from Pseudowire (PW) packets. However, some encapsulations treat the Control Word as optional. As a result, implementations of the CW, for encapsulations for which it is optional, vary by equipment manufacturer, equipment model and service provider network. Similarly, Virtual Circuit Connectivity Verification (VCCV) supports three Control Channel (CC) types and multiple Connectivity Verification (CV) Types. This flexibility has led to reports of interoperability issues within deployed networks and associated drafts to attempt to remedy the situation. This survey of the PW/ VCCV user community was conducted to determine implementation trends. The survey and results are presented in this document. As the document is a survey of what existing implementations do in this area, I agree with editors that it doesn't introduce new security concerns. Editors also clarified that they took precautions to ensure the validity of the sample and the data, in particular they verified email addresses of respondents and that they are representing different companies, not including equipment vendors. I don't have any concerns about security considerations for this document. With no disrespect to document editors, the WG and the shepherding AD, I am however concerns that this document doesn't contain information that is useful for publishing as an RFC. I would be happy to be proven wrong on this. Best Regards, Alexey