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

Hi,

1. In the offer BOTH rtcp-mux and rtcp-mux-only MUSTbe included
2. In the answer rtcp-mux MUST be included or the session should be
terminated. rtcp-mux-only MUST NOT be included.

This removes any variation on what can and cannot be included in the offer
or the answer.

_____________
Roman Shpount

On Tue, Feb 14, 2017 at 4:27 AM, Christer Holmberg <
[email protected]> wrote:

> Hi,
>
> Just to make sure I understand. You are suggesting:
>
> 1. In the offer, the offerer includes BOTH rtcp-mux-only and rtcp-mux. Or,
> is including rtcp-mux still a MAY?
>
> 2. In the answerer, the answerer includes ONLY rtcp-mux. rtcp-mux-only is
> never used in an answer.
>
> Regards,
>
> Christer
>
> From: Roman Shpount <[email protected]>
> Date: Tuesday 14 February 2017 at 00:02
> To: Eric Rescorla <[email protected]>
> Cc: Christer Holmberg <[email protected]>, "[email protected]"
> <[email protected]>
>
> Subject: Re: [MMUSIC] Sending a=rtcp-mux-only w/o a=rtcp-mux
>
> Hi All,
>
> I got the principal question about rtcp-mux-only. Is it needed only as a
> hint to SBC while connection is being established?
>
> It it is a hint to SBC, it does not matter that the answering end point
> does not support it. All it says is that offering end point is not
> expecting any media on rtp port + 1 and will refuse any connection which
> sends it, so SBC does not need to allocate an extra port during setup. If
> this is all, we should not insert rtcp-mux-only in the answer and always
> must include both rtcp-mux-only and rtcp-mux in the offer.
>
> If my understanding is correct, I agree with Eric's logic and we should
> tighten up the mux-exclusive draft.
>
> Regards,
>
> _____________
> Roman Shpount
>
> On Tue, Feb 7, 2017 at 8:15 PM, Eric Rescorla <[email protected]> wrote:
>
>> It seems like that just moves the load onto everyone else who has to
>> process both the
>> case where you have a=rtcp-mux and the one where you do not.
>>
>> -Ekr
>>
>> On Tue, Feb 7, 2017 at 4:26 PM, Roman Shpount <[email protected]> wrote:
>>
>>> Essentially a few test cases less to test.
>>>
>>> Regards,
>>> _____________
>>> Roman Shpount
>>>
>>> On Tue, Feb 7, 2017 at 6:52 PM, Eric Rescorla <[email protected]> wrote:
>>>
>>>> On Tue, Feb 7, 2017 at 12:38 PM, Roman Shpount <[email protected]>
>>>> wrote:
>>>>
>>>>> I want to be able to send rtcp-mux-only. I see plenty of scenarios
>>>>> where my solution communicates exclusively with Web browsers. Once they
>>>>> implement rtcp-mux-only, given the rate with which browsers are updated, I
>>>>> would like, at some point, stop using rtcp-mux instead of inserting legacy
>>>>> flag indefinitely.
>>>>>
>>>>
>>>> What resource are you conserving here? It's not exactly consuming a lot
>>>> of space in the SDP.
>>>>
>>>> -Ekr
>>>>
>>>>
>>>>
>>>> Regards,
>>>>> _____________
>>>>> Roman Shpount
>>>>>
>>>>> On Tue, Feb 7, 2017 at 3:33 PM, Eric Rescorla <[email protected]> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, Feb 7, 2017 at 9:40 AM, Christer Holmberg <
>>>>>> [email protected]> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> >> We had a long discussion about this, with many different
>>>>>>> opinions, and it would take some time to
>>>>>>> >> go through the archive and check everything. But, one opinion was
>>>>>>> that it IS useful to send the
>>>>>>> >> attribute, as it indicates support of the mechanism.
>>>>>>> >
>>>>>>> > What does the other side do with that?
>>>>>>>
>>>>>>> Well, it knows that it doesn't have to include a=rtcp-mux the next
>>>>>>> time it wants to do mux-only.
>>>>>>>
>>>>>>> Obviously, as you suggested in your original e-mail, if we wouldn't
>>>>>>> allow a=rtcp-mux-only without a=rtcp-mux (alt #4) in an offer to begin
>>>>>>> with, it doesn't matter.
>>>>>>>
>>>>>>
>>>>>> Yeah, I don't think this is a plausible option.
>>>>>>
>>>>>> At this point it would be great to hear from anyone who thinks that
>>>>>> we should allow
>>>>>> a=rtcp-mux-only without a=rtcp-mux....
>>>>>>
>>>>>> -Ekr
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> > Is there any precedent for this in SDP?
>>>>>>>
>>>>>>> Not anything I can think of.
>>>>>>>
>>>>>>> Regards,
>>>>>>>
>>>>>>> Christer
>>>>>>>
>>>>>>>
>>>>>>> From: Eric Rescorla <[email protected]>
>>>>>>> Date: Monday 6 February 2017 at 16:32
>>>>>>> To: Christer Holmberg <[email protected]>
>>>>>>> Cc: "[email protected]" <[email protected]>
>>>>>>> Subject: Re: [MMUSIC] Sending a=rtcp-mux-only w/o a=rtcp-mux
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Feb 6, 2017 at 5:57 AM, Christer Holmberg <
>>>>>>> [email protected]> 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
>>>>>>>
>>>>>>> But what harm does it cause?
>>>>>>>
>>>>>>> I don't think that's the standard here. We should only send
>>>>>>> indicators in SDP when they
>>>>>>> do something useful.
>>>>>>>
>>>>>>> -Ekr
>>>>>>>
>>>>>>>
>>>>>>> Regards,
>>>>>>>
>>>>>>> Christer
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Feb 3, 2017 at 9:38 AM, Eric Rescorla
>>>>>>> <[email protected]> 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
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> mmusic mailing list
>>>>>> [email protected]
>>>>>> https://www.ietf.org/mailman/listinfo/mmusic
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>

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