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. The summary of the review is the document is ready for publication. I think the document could be improved slightly by touching on the fact that the service models themselves may involve security parameters. You could add a sentence to the security considerations section following the last sentence: "The service model should expose security related parameters where they are available to the customer." Cheers, Joe