Re: [MMUSIC] Not fixing a=rtcp and rtcp-mux exclusive

[Suhas Nandakumar <[e-mail]>]

On Sun, Jan 24, 2016 at 11:36 PM, Christer Holmberg <
[e-mail]> wrote:

> Hi,
>
> ...
>
> >When ICE is in usage and the Offer want to support a=rtcp-mux-only, it
> does the following
> >a) include a=rtcp-mux-only
> >b) include a=rtcp <rtp-port> <-- RTP port
> >c) include RTCP candidate with port information that matches RTP. No need
> to do new turn allocation for RTCP either.
>
> Note that suggested ICE text says that if an entity only supports mux
> there is no need to include RTCP candidates. Instead the entity will only
> include RTP candidates (there are other mechanisms to indicate whether the
> entity doesn't support/want to use RTCP to begin with).
>
>
[Suhas] As an offerer you have no idea if the Answerer supports RTCP Mux.
So it needs to include RTCP candidates.
This is what RFC5245bis says

"In the case of RTP, this would happen when one agent provides candidates
for RTCP, and the other does not. As another example, the initiating agent
can multiplex RTP and RTCP on the same port [RFC5761]. However, since the
initiating agent doesn't know if the peer agent can perform such
multiplexing, it includes candidates for RTP and RTCP on separate ports. If
the peer agent can perform such  multiplexing, it would include just a
single component for each candidate -- for the combined RTP/RTCP mux. ICE
would end up acting as if there was just a single component for this
candidate."


> Regards,
>
> Christer
>
>