Re: [MMUSIC] Sending a=rtcp-mux-only w/o a=rtcp-mux

[Eric Rescorla <[e-mail]>]

On Mon, Feb 6, 2017 at 4:48 AM, Christer Holmberg <
[e-mail]> wrote:

> Hi,
>
> >Following up to myself, I don't think it's sensible for answers to
> contain a=rtcp-mux-only, because either you accepted mux, in which case all
> is good, or you rejected it, in which case it was rejected.
>
> While I agree that a=rtcp-mux would be enough in the Answer as far as
> indicating mux is concerned, including a=rtcp-mux-only in the Answer does
> indicate that the Answerer supports the mux-exclusive mechanism.
>

I don't see how that's really that useful

-Ekr


>
> Regards,
>
> Christer
>
>
>
> On Fri, Feb 3, 2017 at 9:38 AM, Eric Rescorla <[e-mail]> wrote:
>
>> I have been reading the mux-exclusive document and I'm not sure it says
>> quite what we want. Specifically, S 4.2 says:
>>
>>    When an offerer sends the initial offer, if the offerer wants to
>>    indicate exclusive RTP/RTCP multiplexing for RTP-based media, the
>>    offerer MUST associate an SDP 'rtcp-mux-only' attribute with the
>>    associated SDP media description ("m=" line).
>>
>>    In addition, if the offerer associates an SDP 'rtcp-mux-only'
>>    attribute with an SDP media description ("m=" line), the offerer MAY
>>    also associate an SDP 'rtcp-mux' attribute with the same SDP media
>>    description ("m=" line), following the procedures in [RFC5761].
>>
>> As I understand this text, the offerer may say the following things:
>>
>>  1. No a=rtcp-mux: No muxing.
>>  2. a=rtcp-mux: I am offering RTCP mux
>>  3. a=rtcp-mux-only + a=rtcp-mux: I will only do RTCP mux
>>  4. a=rtcp-mux-only: I will only do RTCP mux (same as #3).
>>
>> I don't think the last of these is sensible. No current implementation
>> will know what to do with a=rtcp-mux-only w/o a=rtcp-mux, so this will
>> result in interop failures. Thus the MAY in the second graf needs to be
>> a MUST.
>>
>> -Ekr
>>
>>
>