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 defines several extensions to prefix advertisements in IS-IS. Summary From a security perspective, the document is ready to be published. Details The document asserts that the new extensions do not have an additional security impact on the protocol, and this makes sense to me. Thanks,     Yaron