Re: [Dart] [AVTCORE] Treatment of RTCP (was Re: Colin Perkins comments - WGLC: draft-ietf-dart-dscp-rtp-02)

"Paul E. Jones" <> Wed, 27 August 2014 22:52 UTC

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From: "Paul E. Jones" <>
To: "Ben Campbell" <>, "Michael Welzl" <>, "Colin Perkins" <>, "Black, David" <>
Date: Wed, 27 Aug 2014 22:52:49 +0000
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Subject: Re: [Dart] [AVTCORE] Treatment of RTCP (was Re: Colin Perkins comments - WGLC: draft-ietf-dart-dscp-rtp-02)
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RTCP might not be used for RTT calculations (it might; I just doubt it's 
terribly useful),  but RTCP might be used to convey QoE measurements or 
one-way delay information useful for RMCAT.

I think there is agreement that the DSCP value applied to the RTCP 
packet for a given SSRC sender should align with the DSCP value used for 
the corresponding RTP packets of that sender. In the case where an AFxx 
class is used, I'm not sure there is agreement (though no disagreement). 
  I stated my view that we should use the lowest drop precedence in that 
case, but others should weigh in.


------ Original Message ------
From: "Ben Campbell" <>
To: "Michael Welzl" <>no>; "Colin Perkins" 
<>rg>; "Paul E. Jones" <>om>; "Black, 
David" <>
Cc: "" 
<>rg>; "" 
<>rg>; " WG" <>
Sent: 8/27/2014 4:48:37 PM
Subject: Re: [Dart] [AVTCORE] Treatment of RTCP (was Re: Colin Perkins 
comments - WGLC: draft-ietf-dart-dscp-rtp-02)

>On Aug 27, 2014, at 3:45 PM, Michael Welzl <> wrote:
>>  I don't know the beginning of this but I can help go up the stack:
>>  for the short dialogue between Colin and me, the conclusion is: Colin 
>>is right. RTCP probably won't be used by congestion control to 
>>estimate the RTT.
>Thanks, Michael, I think that fits with some earlier conversations as 
>Colin and Paul (and David):
>Are we converging on what guidance to put into the DART draft?
>Dart mailing list