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

Essentially a few test cases less to test.

Regards,
_____________
Roman Shpount

On Tue, Feb 7, 2017 at 6:52 PM, Eric Rescorla <ekr@rtfm.com> wrote:

> On Tue, Feb 7, 2017 at 12:38 PM, Roman Shpount <roman@telurix.com> 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 <ekr@rtfm.com> wrote:
>>
>>>
>>>
>>> On Tue, Feb 7, 2017 at 9:40 AM, Christer Holmberg <
>>> christer.holmberg@ericsson.com> 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 <ekr@rtfm.com>
>>>> Date: Monday 6 February 2017 at 16:32
>>>> To: Christer Holmberg <christer.holmberg@ericsson.com>
>>>> Cc: "mmusic@ietf.org" <mmusic@ietf.org>
>>>> Subject: Re: [MMUSIC] Sending a=rtcp-mux-only w/o a=rtcp-mux
>>>>
>>>>
>>>>
>>>> On Mon, Feb 6, 2017 at 5:57 AM, Christer Holmberg <
>>>> christer.holmberg@ericsson.com> 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
>>>> <ekr@rtfm.com> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
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>>
>