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.

Summary: document is ready for publication (with mild reservation).

My thanks to the document editors for producing a readable document.



Mild reservation: when I look at the use cases for PCP Proxy in this 


document (e.g. a consumer router doing NAT, connected to hotel NAT, 


connected to carrier NAT), it's hard to imagine that operational 


environment often fitting within the description of PCP's "simple 


threat model" (RFC6887, section 18.1).  And once you reject the 


simplifying assumptions in that "simple threat model", RFC6877 says 


PCP needs a security mechanism (section 18.2 of RFC6877).  Maybe this 


document should explicity reinforce that need, perhaps citing and 


blocking on draft-ietf-pcp-authentication?