Hi, 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. I think this draft is Ready with issues, though the two issues are relatively minor: 1. The Security Considerations section talks about protecting against injection of PAUSE requests: The way of protecting the RTP session from these injections is to perform source authentication combined with message integrity, to prevent other than intended session participants from sending these messages. I think this paragraph should also mention replay protection, which is needed if the 16-bit PauseID wraps around and the attacker has access to old PAUSE requests. 2. The next paragraph in Security Considerations talks about protecting the multi-party use case against a single malicious participant by individually authenticating participants. In addition to per-participant authentication, I think there also needs to be a requirement for attempted delivery of PAUSE requests to all participants. Without that requirement, an attacker could cause the session to cycle through the Playing, Pausing, and Paused states. To do that, the attacker would send PAUSE requests only to the stream sender, instead of to the whole group. Since no other participants receive the PAUSE request, they do not know to send disapproving RESUMEs until after the stream sender has already paused the stream. (I should note that I'm not particularly familiar with multicast network operations. If it's infeasible for one participant to send a message to another participant without the rest of the group also receiving the message, then I apologize for bringing up a non-issue.) ----- I also have a few nits: Abstract: The RTCP initialism is used without definition. Section 5.4: The SR initialism is used without definition. Section 6.4: I'd suggest changing "As for Paused State" to "As with Paused State". That sentence could also be split up for better readability. -- David Eric Mandelberg / dseomn http://david.mandelberg.org/