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 document describes an architecture for providing IPv4 connectivity across an IPv6-only network. I'm not a fan of documents where the Security Considerations section just says "See these other two specs for the Security Considerations" but in this case it seems that this is adequate. This document is effectively recommends a concatenation stateless v4/v6 translation on the customer side and stateful v6/v4 translation in the provider so it does make sense that the combination of the RFC 6145 and RFC 6146 Security Considerations would do it. And a review of those documents shows that their Security Considerations are thoughtful and well-considered. I did find a few minor typos in section 8.2. In the first paragraph: "a explanation" should be "an explanation" "using combination" should be "using a combination" "is delegated IPv6 prefix" should be "is delegated an IPv6 prefix" Those were the only typos or errors that I found. Note that I am not an expert in address translation or IPv6 operations so there could be hidden security issues here that I didn't find.