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 security considerations cites multiple RFCs. In those RFCs, the security issues related with this work are extensively discussed, although I have to look up those RFCs to find out how to deal with, for example, DDoS attacks. I think it would really helpful if authors can briefly introduce what issues are discuss in those RFCs. Apart from this, this document is ready for publication.