Re: [MMUSIC] WGLC of last set of changes to Bundle (draft-ietf-mmusic-sdp-bundle-negotiation-22)

Magnus Westerlund <magnus.westerlund@ericsson.com> Tue, 23 June 2015 08:14 UTC

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Date: Tue, 23 Jun 2015 10:13:55 +0200
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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Subject: Re: [MMUSIC] WGLC of last set of changes to Bundle (draft-ietf-mmusic-sdp-bundle-negotiation-22)
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Hi,

I looked at the changes and wonder if I spotted an inconsistency? 
Otherwise things looks good.

In Section 5 text was changed to enable non-symmetric RTP usages. 
Resulting in the following text:

    The address:port combination used for sending bundled media
    MAY be the same as the BUNDLE address, used to receive bundled media,
    depending on whether symmetric RTP [RFC4961] is used.


 From 10.3.1:

    If RTP/RTCP multiplexing is enabled, the same address:port
    combination will be used for receiving (and sending) all RTP packets
    and the RTCP packets associated with the BUNDLE group.  Each endpoint
    will send the packets towards the BUNDLE address of the other
    endpoint.

This appears to strongly suggest that one should/must use symmetric RTP 
when doing RTP/RTCP muxing. However, I find nothing in RFC 5761 that 
mandates usage of symmetric RTP with RTP/RTCP Mux, even if it the text 
is written with that as an assumption, I find nothing that prevents 
non-symmetric sending.

Thus, I wonder if the text in 10.3.1 needs to be updated to avoid this 
issue.

Cheers

Magnus Westerlund

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