From: Leo Bicknell [mailto:bicknell () ufp org]
Sent: Monday, February 10, 2003 11:44 AM
To: nanog () nanog org
Subject: Re: VoIP QOS best practices
In a message written on Mon, Feb 10, 2003 at 01:19:08PM
-0500, chaim fried wrote:
happens). There is no reason to implement QOS on the Core.
that, there still seems to be too many issues on the tier 1
with pacekt reordering as they affect h.261/h.263 traffic.
I've got a question about this issue. Many networks reorder
packets for a number of reasons. At least once before I've
attempted to measure the effects of this reordering on a
number of forms of traffic, but I have never understood the
particular effects on VOIP traffic.
Indeed, the two times I was asked to investigate this for
video people it turns out the video receivers /had no ability
to handle out of order frames/. That's right, get one packet
out of order and the video stream goes away until it
resynchronizes. Now, I realize reordering should not happen
to a large percentage of the packets out there, but it also
seems to me any IP application has to handle reordering or
it's not really doing IP.
So what's the real problem here? Are the VOIP boxes unable
to handle out of order packets? Do the out of order packets
simply arrive far enough delayed to blow the delay budget?
What percentage of reordered packets starts to cause issues?
Leo Bicknell - bicknell () ufp org - CCIE 3440
PGP keys at http://www.ufp.org/~bicknell/
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