I 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 with the intent of improving security requirements and considerations in IETF drafts.   Comments 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.   This document is intended to clarify RFC 5584, which describes BFD for MPLS LSPs (try saying that quickly 5 times!).   I didn’t find any security problems with this very brief document. The Security Considerations section refers to the RFC being “clarified” and additionally cites RFC 4379. RFC 4379 contains a reasonable Security Considerations section. RFC 5584 contains a 1-paragraph Security Considerations section that cites 4 RFCs: 5880, 5883, 4379, and 5290. RFC 5880 is the base document for BFD, and it contains a 2-page Security Considerations section, although several portions of the text are out of date. RFC 5883 contains a trivial, 1 paragraph Security Considerations section. RFC 4379 contains a decent 1-page Security Considerations section. RFC 5290 is the MPLS/GMPLS Security Framework, a substantial document discussing security for MPLS.   Considering the focus of this document and its 6-page length, its references to the Security Considerations sections of the other RFCs suffice.