Last Call Review of draft-ietf-avtcore-6222bis-03
review-ietf-avtcore-6222bis-03-genart-lc-holmberg-2013-06-12-00

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please see the FAQ at <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>



Document:                         draft-ietf-avtcore-6222bis-03



Reviewer:                           Christer Holmberg



Review Date:                     10 June 2013



IETF LC End Date:             11 June 2013



IETF Telechat Date:         N/A



Summary:  There is a minor issue, described below, that I think should be
clarified before the document is published.



Major Issues: None



Minor Issues:



Section 4.1 says:



   “The RTCP CNAME can be either persistent across different RTP sessions

   for an RTP endpoint or unique per session, meaning that an RTP

   endpoint chooses a different RTCP CNAME for each RTP session.”



…and:



   “An RTP endpoint that is emitting multiple related RTP streams that

   require synchronization at the other endpoint(s) MUST use the same

   RTCP CNAME for all streams that are to be synchronized.  This

   requires a short-term persistent RTCP CNAME that is common across

   several RTP streams, and potentially across several related RTP

   sessions.  A common example of such use occurs when lip-syncing audio

   and video streams in a multimedia session, where a single participant

   has to use the same RTCP CNAME for its audio RTP session and for its

   video RTP session.  Another example might be to synchronize the

   layers of a layered audio codec, where the same RTCP CNAME has to be

   used for each layer.”



…etc.



The text talks about the CNAME being unique within an RTP session, or to span
over multiple RTP sessions, but it seems to omit that, *

within

* an RTP session, you can also use *

different

* CNAME values, if e.g. there is no
 synchronization requirement between the RTP streams.





Editorial nits: None



Best regards,



Christer