Re: [MMUSIC] BUNDLE and RTCP

Christer Holmberg <christer.holmberg@ericsson.com> Mon, 19 October 2015 17:48 UTC

Return-Path: <christer.holmberg@ericsson.com>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2B2E31A8F4C for <mmusic@ietfa.amsl.com>; Mon, 19 Oct 2015 10:48:48 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.601
X-Spam-Level:
X-Spam-Status: No, score=-3.601 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, J_CHICKENPOX_14=0.6, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ur-8tFjlGBSh for <mmusic@ietfa.amsl.com>; Mon, 19 Oct 2015 10:48:46 -0700 (PDT)
Received: from sessmg23.ericsson.net (sessmg23.ericsson.net [193.180.251.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B72BD1A898F for <mmusic@ietf.org>; Mon, 19 Oct 2015 10:48:45 -0700 (PDT)
X-AuditID: c1b4fb2d-f79626d000004282-2a-56252cfbabd8
Received: from ESESSHC023.ericsson.se (Unknown_Domain [153.88.253.124]) by sessmg23.ericsson.net (Symantec Mail Security) with SMTP id B6.9A.17026.BFC25265; Mon, 19 Oct 2015 19:48:44 +0200 (CEST)
Received: from ESESSMB209.ericsson.se ([169.254.9.61]) by ESESSHC023.ericsson.se ([153.88.183.87]) with mapi id 14.03.0248.002; Mon, 19 Oct 2015 19:48:43 +0200
From: Christer Holmberg <christer.holmberg@ericsson.com>
To: Paul Kyzivat <pkyzivat@alum.mit.edu>, "mmusic@ietf.org" <mmusic@ietf.org>
Thread-Topic: [MMUSIC] BUNDLE and RTCP
Thread-Index: AdEJzH14LMfHNeeTQ5m0MrbuciOcLQAASvagABTmWQAABPyt0P//7NmA///YEmCAAKJDAP//uV9ggAB0X4D//9O1MA==
Date: Mon, 19 Oct 2015 17:48:42 +0000
Message-ID: <7594FB04B1934943A5C02806D1A2204B37B74FB0@ESESSMB209.ericsson.se>
References: <7594FB04B1934943A5C02806D1A2204B37B66DC9@ESESSMB209.ericsson.se> <7594FB04B1934943A5C02806D1A2204B37B66EEC@ESESSMB209.ericsson.se> <56248496.2050408@gmail.com> <7594FB04B1934943A5C02806D1A2204B37B6CAC0@ESESSMB209.ericsson.se> <562495FD.7020603@gmail.com> <7594FB04B1934943A5C02806D1A2204B37B6CCC5@ESESSMB209.ericsson.se> <5624FC9C.90904@alum.mit.edu> <7594FB04B1934943A5C02806D1A2204B37B74CDC@ESESSMB209.ericsson.se> <562522FB.40706@alum.mit.edu>
In-Reply-To: <562522FB.40706@alum.mit.edu>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [153.88.183.149]
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrELMWRmVeSWpSXmKPExsUyM+Jvje4fHdUwg5YZzBZTlz9msVix4QCr A5PH3/cfmDyWLPnJFMAUxWWTkpqTWZZapG+XwJXRtOUFa8EvxYrrj98zNzA+k+xi5OSQEDCR aL31jxXCFpO4cG89WxcjF4eQwFFGifc7F7NCOIsZJZa/PMzexcjBwSZgIdH9TxukQUTAV+LZ 49tsILawgKrEyf27mSHiahJ3NtyEsrMkVm9oALNZgGo+9v8HW8YL0nuzhxFi/m1miY3nNrKA JDgFtCRuX/jOBGIzAl30/dQaMJtZQFzi1pP5TBCXCkgs2XOeGcIWlXj5GOYDJYm1h7ezQNTr SCzY/YkNwtaWWLbwNTPEYkGJkzOfsExgFJ2FZOwsJC2zkLTMQtKygJFlFaNocWpxcW66kbFe alFmcnFxfp5eXmrJJkZgpBzc8lt3B+Pq146HGAU4GJV4eB+0qYQJsSaWFVfmHmKU5mBREudt YXoQKiSQnliSmp2aWpBaFF9UmpNafIiRiYNTqoFRI0psrcXtb50ibxbJz7n9oF3t8bMellPs N0ObrH4WWxQLPJh127NBK5fz3GZHg8snXRoEpV2f7nXnPPLW6PpKIS5XjZ1bljwVOit9/3La /h0nS5JUZut3WB8VvzFH54i68GGpJ6WPPGdbnDkslZHO48fxX7AgQ/DHg81XwhPtuq/t1zcr eH1EiaU4I9FQi7moOBEALXOEP3UCAAA=
Archived-At: <http://mailarchive.ietf.org/arch/msg/mmusic/ohgV2sCAr7I_kPDDg6xYct6HpGs>
Subject: Re: [MMUSIC] BUNDLE and RTCP
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/mmusic/>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 19 Oct 2015 17:48:48 -0000

Hi,

>>> Good discussion.
>>>
>>> How about the following:
>>>
>>> If there is an RTP m-line in the bundle, and rtcp-mux is *not* 
>>> negotiated, then the rtcp port is determined according to the rules 
>>> for the first m-line selected in the bundle group. If *that* line has, and allows, an a=rtcp, then that is used. If that line doesn't have a=rtcp, then port+1 is used, even if this isn't an rtp m-line.
>>
>> Sure. But, as the offerer doesn't know for sure which m- line will be selected, it always has to be prepared to use port+1, so why not use port+1 to begin with?
>>
>> I guess my question is whether someone really needs a=rtcp with BUNDLE? As far as I know, most current implementations do rtcp-mux, and for those that don't/can't there is always port+1.
>
> IIRC the original reason for a=rtcp was because there are cases when it is hard to get an even/odd pair of ports. If the offerer is in that situation, then mandating port+1 isn't going to work.

Ok. So, I guess one question is whether such situations still can occur.

> I am coming around to agree with just requiring rtcp-mux with bundle.
> I don't unsderstand why RTCP was *ever* defined to run on a separate port. Maybe it was just a mistake.

As far as I know, some people still wish to be able to use separate ports for RTP and RTCP, even when using BUNDLE. I'd like to know whether port+1 works for them.

Regards,

Christer



>> (Right now there isn't any way to have a bundle group with more than 
>> one non-rtp m-line, but that might not always be so.)
>
> Correct.
>
> Regards,
>
> Christer
>
>
>
> On 10/19/15 3:35 AM, Christer Holmberg wrote:
>> Hi,
>>
>> ...
>>
>> ...
>>
>> ...
>>
>>      HOWEVER, we could make it SIMPLE and either:
>>
>>      1)*Mandate usage of rtcp-mux with BUNDLE*. I.e. if BUNDLE is
>>      negotiated, rtcp-mux MUST be used.
>>
>>      This was already suggested in the past, but Paul(?) said we should
>>      not make such restriction without a good reason. I think the current
>>      issue is a good reason :)
>>
>>      m=data channel 10000
>>
>>      m=rtp 11111
>>
>>      a=rtcp-mux
>>
>>      m=rtp 11222
>>
>>      a=rtcp-mux
>>
>>      2)*Mandate usage of either rtcp-mux OR the default "+1" port with
>>      BUNDLE*. I.e. if BUNDLE is negotiated, rtcp-mux or "+1" MUST be
>>      used. The selection is based on whether the rtcp-mux attribute was
>>      included in the offer/answer or not.
>>
>>      m=data channel 10000             // rtcp-mux
>>
>>      m=rtp 11111
>>
>>      a=rtcp-mux
>>
>>      m=rtp 11222
>>
>>      a=rtcp-mux
>>
>>      m=data channel 10000             // "+1"
>>
>>      m=rtp 11111
>>
>>      m=rtp 11222
>>
>>      The solutions above would not allow explicit negotiation of an RTCP
>>      port when BUNDLE is used, but maybe we could live with that?
>>
>>> Well, I could live with both of your suggestions, but I thought you
>> wanted a solution that can also negotiate which a=rtcp attribute to use.
>>
>>> If nobody really needs something like that , I would prefer 1) as it
>> removes the needs for several implementation option that would only 
>> be needed to cover full backwards compatibility but would hardly be used.
>>
>> Personally I don't have a strong preference, but as far as I know 
>> there may be environments where separate ports for RTP and RTCP are 
>> desired - even if BUNDLE is used.
>>
>>>> Now, if we can agree on a way forward before Yokohama, you won't 
>>>> have to
>> sit listening to me talking about BUNDLE at the meeting :)
>>>
>>> Well, I wouldn't be sitting there anyhow but understand that your
>> motivation to speak there about BUNDLE again is probably limited.
>>
>> I don't mind talking about BUNDLE - but I'd like to talk about it in 
>> the context of the great RFC that we have published :)
>>
>> Regards,
>>
>> Christer
>>
>>
>>
>> _______________________________________________
>> mmusic mailing list
>> mmusic@ietf.org
>> https://www.ietf.org/mailman/listinfo/mmusic
>>
>
> _______________________________________________
> mmusic mailing list
> mmusic@ietf.org
> https://www.ietf.org/mailman/listinfo/mmusic
>