Re: [Dart] draft-dart-dscp-rtp - way forward

Harald Alvestrand <harald@alvestrand.no> Fri, 29 August 2014 10:48 UTC

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Date: Fri, 29 Aug 2014 12:48:41 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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To: Ben Campbell <ben@nostrum.com>, "Black, David" <david.black@emc.com>
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Subject: Re: [Dart] draft-dart-dscp-rtp - way forward
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I think the text in -04 looks reasonable.

I would like to do two things:

- The justification for "single DSCP" in SCTP and DCCP is "we don't know 
what will happen".
A logical consequence is that this recommendation might change as the 
result of further study, so we might want to add near the bottom of 
section 5 a sentence saying "This recommendation may be revisited if 
experiments and analysis shows compelling reasons to change it."

- I still think the ban against RTCP multi-stream reporting optimization 
is completely wrong. The reports will correctly reflect the differing 
packet loss behaviours of the incoming RTP streams, and that's all they 
should be required to do.

I regard the latter as somewhat important. The former is more a matter 
of taste (if we're arguing based on ignorance, allow for the case where 
ignorance becomes knowledge).


On 08/28/2014 10:25 PM, Ben Campbell wrote:
> Okay, works for me.
>
> Thanks!
>
> Ben.
>
> On Aug 28, 2014, at 3:15 PM, Black, David <david.black@emc.com>; wrote:
>
>>> If we think we can close this as not a real issue (or at least not an issue we
>>> plan to address), but there's some risk it might come back up at IETF LC, then
>>> that's fine. But if we are saying there is an open issue that needs closure,
>>> but we can close it during IETF last call, then I have reservations. The
>>> version that goes to IETF LC should be one that the working group believes to
>>> be as complete is it's going to get.
>> In private discussion, both Harald and I favored saying less (rather than more)
>> about RMCAT in this DART draft.  For that reason I think "at least not
>> an issue we plan to address" is a valid characterization of this item.
>>
>> Thanks,
>> --David
>>
>>> -----Original Message-----
>>> From: Ben Campbell [mailto:ben@nostrum.com]
>>> Sent: Thursday, August 28, 2014 3:44 PM
>>> To: Black, David; Harald Tveit Alvestrand
>>> Cc: dart@ietf.org
>>> Subject: Re: [Dart] draft-dart-dscp-rtp - way forward
>>>
>>> (as chair)
>>>
>>> On Aug 28, 2014, at 1:12 PM, Black, David <david.black@emc.com>; wrote:
>>>
>>>> [E] Open issue: Harald Alvestrand's concerns about "differential treatment"
>>>> wrt Section 5.1 .  I don't completely understand these concerns, and suspect
>>>> that they may require an email discussion across the DART and RMCAT WGs
>>>> to sort through.
>>>>
>>>> --> Deferred - Harald wanted to think about this, and I've seen nothing
>>>> --> further.  I'd suggest that IETF Last Call as an appropriate opportunity
>>>> --> to share any further thoughts, so I don't think there's anything to be
>>> done
>>>> --> about this now.
>>> I have mixed feelings on this.
>>>
>>> If we think we can close this as not a real issue (or at least not an issue we
>>> plan to address), but there's some risk it might come back up at IETF LC, then
>>> that's fine. But if we are saying there is an open issue that needs closure,
>>> but we can close it during IETF last call, then I have reservations. The
>>> version that goes to IETF LC should be one that the working group believes to
>>> be as complete is it's going to get.
>>>
>>> David, thoughts?
>>>
>>> Harald, do you care to comment further?