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. There is a big risk here, and the security considerations section captures it very succinctly: "The communication ... is security sensitive and requires authentication, integrity and replay protection." Perhaps that should be repeated earlier in the doc. Editorial: it's not clear to me why this is being defined only for DHCPv6. A sentence explaining that would be helpful. -- Sam