Re: [MMUSIC] BUNDLE: Modified text based on decision to mandate RTP/RTCP mux for bundled RTP-based media

[Paul Kyzivat <[e-mail]>]

Christer,

This works for me. It solves the problem *for bundle* while sidestepping 
the problem for unbundled m-lines.

Of course, an offerer who is trying to establish a new bundle group, and 
who does not control port+1 still has a problem of how to safely 
construct the offer. This is just the problem with a=rtcp, and has 
nothing to do with bundle. Such an offerer will cope with this however 
it can. (E.g., hope for the best.)

	Thanks,
	Paul

On 11/6/15 3:03 AM, Christer Holmberg wrote:
> Hi,
>
> Based on the decision to mandate RTP/RTCP mux for BUNDLE, I’ve modified
> the associated section in BUNDLE. See below.
>
> (We may need some more text, based on where we go with the mux-only issue)
>
> For the Github fans, the text can also be found at:
>
> https://github.com/cdh4u/draft-sdp-bundle
>
> (Note that it is a private repo)
>
> Regards,
>
> Christer
>
> -------------------------
>
> 10.3.  RTP/RTCP Multiplexing
>
> 10.3.1.  General
>
>     Within a BUNDLE group, the offerer and answerer MUST enable RTP/RTCP
>
>     multiplexing [RFC5761] for the RTP-based media associated with the
>
>     BUNDLE group.
>
>     When RTP/RTCP multiplexing is enabled, the same address:port
>
>     combination will be used for 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.  The
>
>     same address:port combination MAY be used for receiving RTP packets
>
>     and RTCP packets.
>
> 10.3.2.  SDP Offer/Answer Procedures
>
> 10.3.2.1.  General
>
>     This section describes how an offerer and answerer use the SDP 'rtcp-
>
>     mux' attribute [RFC5761] to negotiate usage of RTP/RTCP multiplexing
>
>     for RTP-based media associated with a BUNDLE group.
>
>     The procedures in this section only apply to RTP-based "m=" lines.
>
> 10.3.2.2.  Generating the Initial SDP Offer
>
>     When an offerer generates an initial offer, the offerer MUST
>
>     associate an SDP 'rtcp-mux' attribute [RFC5761] with each bundled
>
>     RTP-based "m=" line (including any bundle-only "m=" line) in the
>
>     offer.
>
>     NOTE: The offerer might also associate an SDP 'rtcp' attribute
>
>     [RFC3605] with a bundled "m=" line, excluding a bundle-only "m="
>
>     line, in order to provide a fallback port for RTCP.  However, the
>
>     fallback port will only be used in case the answerer does not include
>
>     the "m=" line in the BUNDLE group in the associated answer.
>
>     In the initial offer, the IP address and port combination for RTCP
>
>     MUST be unique in each bundled RTP-based "m=" line (excluding a
>
>     'bundle-only' "m=" line), similar to RTP.
>
> 10.3.2.3.  Generating the SDP Answer
>
>     When an answerer generates an answer, if the offerer indicated
>
>     support of RTP/RTCP multiplexing [RFC5761] within a BUNDLE group in
>
>     the associated offer, the answerer MUST accept usage of RTP/RTCP
>
>     multiplexing within the BUNDLE group.  If an SDP "rtcp-mux" attribute
>
>     was not associated with a bundled "m=" line in the associated offer,
>
>     the answerer MUST NOT included that "m=" line in the BUNDLE group.
>
>     When the answerer accepts the usage of RTP/RTCP multiplexing within
>
>     the BUNDLE group, it MUST associate an SDP 'rtcp-mux' attribute with
>
>     each bundled RTP-based "m=" line in the answer.  The answerer MUST
>
>     NOT associate an SDP 'rtcp' attribute with any bundled "m=" line in
>
>     the answer.  The answerer will use the port value of the selected
>
>     offerer BUNDLE address for sending RTP and RTCP packets associated
>
>     with each RTP-based bundled "m=" line towards the offerer.
>
>     If the usage of RTP/RTCP multiplexing within a BUNDLE group has been
>
>     negotiated in a previous offer/answer transaction, the answerer MUST
>
>     associate an SDP 'rtcp-mux' attribute with each bundled RTP-based
>
>     "m=" line in the answer.
>
> 10.3.2.4.  Offerer Processing of the SDP Answer
>
>     When an offerer receives an answer, if the answerer has accepted the
>
>     usage of RTP/RTCP multiplexing (see Section 10.3.2.3), the answerer
>
>     follows the procedures for RTP/RTCP multiplexing defined in
>
>     [RFC5761].  The offerer will use the port value associated with the
>
>     answerer BUNDLE address for sending RTP and RTCP packets associated
>
>     with each RTP-based bundled "m=" line towards the answerer.
>
>     NOTE: If is considered a protocol error if the answerer has not
>
>     accpeted the usage of RTP/RTCP multiplexing for RTP-based "m=" lines
>
>     that the answerer included in the BUNDLE group.
>
> 10.3.2.5.  Modifying the Session
>
>     When an offerer generatees a subsequent offer, it MUST associate an
>
>     SDP 'rtcp-mux' attribute with each RTP-based bundled "m=" line
>
>     (including any bundled "m=" line that the offerer wants to add to the
>
>     BUNDLE group), unless the offerer wants to disable or remove the "m="
>
>     line from the BUNDLE group.
>
>
>
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