Re: [MMUSIC] RE : I-D Action: draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt

[Flemming Andreasen <[e-mail]>]

On 3/14/13 3:50 PM, Andrew Allen wrote:
>
> I am not sure if anything is recorded in any minutes but we had an 
> offline discussion to remove the roadblock on this with Jonathan to 
> address his concern that this was a potential alternative to ICE and 
> addressed this with the current text. This text and the reason behind 
> it I think was pointed out on the list during Quebec or shortly after.
>
Can you find the message or recall who sent it ?

Also, the Quebec meeting was in July 2011. Tracing back we have:

a) The initial (?) individul versions of the draft (2008/2009): 
http://tools.ietf.org/html/draft-garcia-mmusic-sdp-misc-cap
b) Another individual take on the draft (August 2011+): 
http://tools.ietf.org/html/draft-garcia-mmusic-sdp-miscellaneous-caps
c) The intial WG version of the draft (March 2012+): 
http://tools.ietf.org/html/draft-ietf-mmusic-sdp-miscellaneous-caps

The "a)" version did indeed position the draft as an alternative to ICE, 
however all "b)" and "c)" versions changed this as per the previous 
discussion.

I'm still looking for anything written anywhere that suggests that the 
text in "b)" and "c)" does not represent consensus and/or that consensus 
is that the mechanism MUST always be prohibited from negotiating IP4/IP6 
addresses (as opposed to just when ICE is not available).

Thanks

-- Flemming

>
> *From*: Flemming Andreasen [mailto:[e-mail]]
> *Sent*: Thursday, March 14, 2013 02:45 PM Central Standard Time
> *To*: Stach, Thomas <[e-mail]>
> *Cc*: Andrew Allen; [e-mail] <[e-mail]>; 
> [e-mail] <[e-mail]>
> *Subject*: Re: AW: [MMUSIC] RE : I-D Action: 
> draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
>
> As to ccap not being an alternative to ICE we are all in agreement on 
> that - the lack of port negotiation alone makes that clear (it simply 
> doesn't work without that).
>
> As to ccap being explicitly forbidden to express IP4 and/or IP6 
> addresses as alternatives, can somebody please point me to either 
> meeting minutes or mailing list discussion to that effect ? The only 
> thing I have found is the port discussion we had in Taipei, where we 
> agreed not to add a port capability. From 
> http://www.ietf.org/proceedings/82/minutes/mmusic.htm:
> <quote>
>
> Miscellaneous Capabilities Negotiation in SDP (Simo Veikkolainen, 10)
>
> =====================================================================
>
> draft-garcia-mmusic-sdp-miscellaneous-caps-00.txt 
> <http://www.ietf.org/id/draft-garcia-mmusic-sdp-miscellaneous-caps-00.txt>
>
> Simo presented hisslides 
> <http://www.ietf.org/proceedings/82/slides/mmusic-8.pptx>.
>
> Simo explained the need to be able to indicate alternative port 
> numbers, but PSTN media, port number doesn't make sense. The CS draft 
> says use port number 9 (the discard port). We have to put something 
> there because required by SDP syntax. If an RTP stream is offered, 
> then a regular port number should be written instead. The problem 
> arises when both CS and RTP streams are offered at the same time, one 
> as an alternative of the other. Then, the port number makes sense for 
> RTP but not for CS, but still, there is a single place to write the 
> port number in the SDP, so, has to be shared by both alternative media 
> streams.
>
> Possible solutions:
>
> 1. Circuit-switched media uses the same port as RTP media even though 
> the port is not really used
>
> 2. Extend capneg with a port number capability attribute, restricting 
> its use to cases where ICE cannot be used.
>
> 3.Select anything as a port number and say "do not care on reception".
>
> Jonathan Lennox suggested saying that port numbers not equal 0 have to 
> be ignored.
>
> Hadriel Kaplan asked if middle boxes not supporting this stuff can be 
> broken. The discussion is moved offline.
>
> There are questions on how could be possible to indicate preference 
> for one media stream above the alternative.
>
> Miguel Garcia suggested using port 9 if it works. If not take anything 
> not equal 0. Receiver has to ignore.
>
> In general, there was pushback on the port negotiation approach. The 
> authors should explore a solution along the third option: write the 
> RTP port number in the "m=" line. If CS alternative is chosen, discard 
> the port number on reception.
> </quote>
>
>
> Apart from that, the only thing I'm aware of is the 4 WG versions of 
> this draft which have all said the same about IP4/IP6 and ICE, and 
> again, that text was both WGLC'ed and reviewed by 2 volunteers without 
> any concerns. Where does the alternate understanding come from ?
>
> Thanks
>
> -- Flemming
>
>
>
> On 3/14/13 2:16 PM, Stach, Thomas wrote:
>> This is also my understanding
>> ... although my initially proposed text does not reflect this correctly.
>> Regards
>> Thomas
>>
>>     ------------------------------------------------------------------------
>>     *Von:* [e-mail] [mailto:[e-mail]]
>>     *Im Auftrag von *Andrew Allen
>>     *Gesendet:* Donnerstag, 14. März 2013 14:10
>>     *An:* [e-mail]; [e-mail]
>>     *Cc:* [e-mail]
>>     *Betreff:* Re: [MMUSIC] RE : I-D Action:
>>     draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
>>
>>
>>     My understanding also was that we agreed that CCAP was not an
>>     alternative to ICE.
>>
>>
>>     *From*: Jonathan Lennox [mailto:[e-mail]]
>>     *Sent*: Thursday, March 14, 2013 01:06 PM Central Standard Time
>>     *To*: Flemming Andreasen <[e-mail]>
>>     *Cc*: [e-mail]
>>     <[e-mail]>; Andrew Allen; [e-mail]
>>     <[e-mail]>
>>     *Subject*: Re: [MMUSIC] RE : I-D Action:
>>     draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
>>
>>
>>     On Mar 14, 2013, at 1:43 PM, Flemming Andreasen wrote:
>>
>>>     On 3/14/13 11:40 AM, [e-mail] wrote:
>>>>     Re-,
>>>>     What is important is the quality of produced documents. The
>>>>     content of the document is not frozen and unless I'm mistaken
>>>>     there is not IETF LC.
>>>>
>>>     Correct.
>>>>     What I understand from the text in the draft is: ccap is
>>>>     allowed to signal an IPv4@ and IPv6@ if ICE is not supported.
>>>>
>>>     ccap is not prohibited from doing so in the absence of ICE,
>>>     however as explained in the document
>>>     1) When the IETF Standard Track mechanism ICE is available, ccap
>>>     MUST NOT signal an IPv4/IPV6 address alternative.
>>>     2) The draft does (intentionally) not provide a full solution
>>>     for negotiating alternative IP-addresses since we have a
>>>     Standards Track mechanism for doing so (ICE).
>>
>>     Hi, Fleming --
>>
>>     My understanding of the WG consensus -- and my interpretation of
>>     the text in the draft -- was stronger than this: ccap MUST NOT be
>>     used for the kinds of alternatives ICE can express, whether or
>>     not ICE is actually being used in a particular offer/answer.
>>
>>     If we're getting divergent interpretations of this document, we
>>     probably do need to update its text.
>>
>>     --
>>     Jonathan Lennox
>>     [e-mail] <mailto:[e-mail]>
>>
>>
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