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 is an architecture document describing a framework for media server control which combines elements from several related working groups and protocols. The framework described in this document consists of 3 elements: the application server, the media server, and the user agent. The document focuses on the interactions between the application server and the media server, and declares the user agent interactions to be out of scope. The security considerations section says that media servers use the security mechanisms of SIP to authenticate requests from application servers, and to ensure the integrity of those requests, and says that this ensures that only authorized application servers may access the media server and impact its resources. I have two concerns: first, the current security considerations section focuses on the media server and how to protect against malicious application servers (or AS impersonators) -- it should also address the flip side of this, i.e. what happens if someone impersonates the media server, and what, if anything, should be done? If this is addressed in some other related document, then perhaps a pointer to that other document would be helpful. My other concern is a bit more nebulous: this work seems to cut across multiple other efforts (more than I have time to seriously review right now), and while I think it makes sense to reference the security considerations of other documents when they adequately address the problems at hand, I think the wg (and security ADs) will want to be sure that the particular threats of this framework are explicitly called out and completely addressed. This architecture document may or may not be the right place to do that. --Scott