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 specifies a new Network Address Translator (NAT) traversal mode for the Host Identity Protocol (HIP). While I am not a HIP guy, it seems ready for publication. It's well-written and the security considerations section is thorough. The only bit that raised a question was in section 4, which states "it should be noted that HIP version 2 [RFC7401 ] instead of HIPv1 is expected to be used with this NAT traversal mode". Earlier in the document, it states the draft is based on HIPv2. Are there any considerations worth noting in the cases where HIPv1 is used or should section 4 be revised to require v2?