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. Status: ready with nits. The document claims to introduce no new security exposure, but it seems to me that it is designed to ensure routing occurs correctly in situations where it previously didn't - this may result in unexpected exposure of networks that previously were unreachable. I think this is a nit, because clearly such networks were poorly designed in the first place, but perhaps a mention should be made?