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 a mandatory algorithm transition procedure for the RPKI. It describes a single method, comprised of four phases and six milestones. Each phase discusses a strategy for rollback of the new algorithm. The algorithm transition procedure seems complete, and the security considerations section is adequate. One statement in the discussion of Phase 4 is confusing (Section 4.7). It first states: "RPs MAY validate signed product sets using Suite C. However, RPs SHOULD NOT assume that the collection of Suite C product sets is complete." Later it notes that Suite A could be deprecated, and states: "At this stage, RPs are still capable of processing Suite C signed products, so the RPKI is still viable." But if the Suite C product sets may be incomplete, how is the RPKI still viable? This should be clarified. Nits: - Section 3, "Corresponds" definition: s/Resoureces/Resources/ - Section 4.1, "End Of Life (EOL) Date definition: s/is MUST/MUST/ - Section 7, last paragraph. The final sentence would be clearer if it read "Since Suite C products are being deprecated during Phase 4, a CA may revoke certificates issued under Suite C without revoking them under Suite A." Ignore if you don't agree. Brian