[MMUSIC] Review of draft-marjou-mmusic-sdp-rtsp-01

["Martin Stiemerling" <Stiemerling at nw.neclab.eu>]

Hi all,

I did a review of draft-marjou-mmusic-sdp-rtsp-01, mainly for curiosity why this is needed.
I didn't find the answer in this draft yet. 

The draft proposes a coupling between SIP and RTSP. Whereas SIP is used for session control and RTSP for media streaming control. 

Here are some detailed comments:
- Section 1 Intro: It states that SIP is used as rendezvous point and for NAT traversal. However, there is no word at all about RTSP 2.0's NAT traversal support. Is this intentionally left out or did you just miss this?

- Section Problem Analysis: I actually do miss the content in here. The problems reported are more or less just supposed problems, but no stuffed with real meat. For instance, in the second para (the video surveillance thingy) it is not obvious at all why RTSP is not working... And it is not that clearly "RTSP only or another media control protocol is not sufficient".
However, the only reasoning that is obvious is written in the last paragraph (yes -- there are other standards bodies). This reason is also highlighted by Section 13. 

- Section 7, 1st para establishment of media control...: Why is actually required to negotiate SDP? You anyway write that the SDP description of the presentation is downloaded by some other means, such as HTTP. Negotiating SDP would be only required if the SDP offered by the server is not known in advance or by means of RTSP's DESCRIBE, http, etc.

- Section 7, general: I assume that the terminology got mixed up somehow or the different ideas are not presented properly, at least to my understanding. Or why should step one setup the media delivery channel? Isn't it first about negotiation what should happen in the media delivery channel? Setup would be done later by RTSP. Or do I miss the point here?

- Section 7, general: What is the error correlation between the SIP and RTSP part? Who is in charge for controlling the RTP streams (if used)?

I have read any further, as, at least IMHO, the technical base in the first seven sections is weak and hard to understand. 

  Martin

stiemerling at nw.neclab.eu   <== NEW ADDRESS

NEC Laboratories Europe - Network Research Division
NEC Europe Limited | Registered Office: NEC House, 1 Victoria Road, London W3 6BL | Registered in England 2832014 
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