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 nicely documents what seems to be a rather clever way of helping IPv6 and IPv4 interoperate, using a sort of address encapsulation mechanism. I like the document, I think the scheme it documents is interesting and useful, and I see no problems with publication (including from a security perspective; the Security Considerations section seems adequate). The document lists its intended status as Informational, while the tracker shows it as Experimental. Either could work, of course, but Informational seems more appropriate here. Barry -- Barry Leiba (barryleiba at computer.org) http://internetmessagingtechnology.org/