Re: [xrblock] I-D Action: draft-ietf-xrblock-rtcp-xr-discard-05.txt

"Romascanu, Dan (Dan)" <dromasca@avaya.com> Thu, 26 July 2012 00:26 UTC

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Date: Thu, 26 Jul 2012 02:26:29 +0200
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Thread-Topic: [xrblock] I-D Action: draft-ietf-xrblock-rtcp-xr-discard-05.txt
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From: "Romascanu, Dan (Dan)" <dromasca@avaya.com>
To: Colin Perkins <csp@csperkins.org>, Qin Wu <bill.wu@huawei.com>
Cc: xrblock@ietf.org
Subject: Re: [xrblock] I-D Action: draft-ietf-xrblock-rtcp-xr-discard-05.txt
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+1

... but (question to Colin) - do you believe that this reference needs
to be Normative? 

Dan




> -----Original Message-----
> From: xrblock-bounces@ietf.org [mailto:xrblock-bounces@ietf.org] On
> Behalf Of Colin Perkins
> Sent: Wednesday, July 25, 2012 10:59 AM
> To: Qin Wu
> Cc: xrblock@ietf.org
> Subject: Re: [xrblock] I-D Action: draft-ietf-xrblock-rtcp-xr-discard-
> 05.txt
> 
> On 25 Jul 2012, at 07:49, Qin Wu wrote:
> > Based on Alan's proposal to the open issue mentioed below, we like
to
> add one new section after SDP signaling section as follows:
> > "
> > 6. Consideration for duplicate packets discards
> >
> > Early/ late discards are usually regarded as a symptom of PDV due to
> congestion (or route changes) however duplicate packets discards have
> quite different causes.
> >
> > (a) A few duplicate packets can indicate some form of Layer 1/2 LAN
> problem. This would not need to be an accurate measure - more of a
> general barometer.
> >
> > (b) If the number of duplicate packets is very high then this may be
> due to RTP replication - and if this is the case then you would want
to
> compare the number of duplicate packets to the number of received
> packets in the same time interval. If the duplicate packet count is X%
> of the received packet count, this indicates that a (100-X)% packet
loss
> rate is being "hidden" by the replicated packets, and  it is very
useful
> to know the actual loss rate(useful to indicate that replication
should
> be kept "on" and helpful to know that there are some network issues
that
> need to be investigated).
> > "
> 
> Duplicating RTP packets in this way for robustness is a very bad idea,
> since - as you note - it disrupts all the RTCP statistics. If you need
> to send duplicate streams, draft-ietf-avtext-rtp-duplication-00
> describes how to do it without breakage. If you are going to mention
> duplication, I'd recommend including a reference to the working group
> draft to show how to do it right.
> 
> --
> Colin Perkins
> http://csperkins.org/
> 
> 
> 
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