[97846] in North American Network Operators' Group
Re: TCP congestion
daemon@ATHENA.MIT.EDU (Joe Loiacono)
Thu Jul 12 15:52:23 2007
In-Reply-To: <30366.27320.qm@web30805.mail.mud.yahoo.com>
To: Philip Lavine <source_route@yahoo.com>
Cc: nanog <nanog@merit.edu>, owner-nanog@merit.edu
From: Joe Loiacono <jloiacon@csc.com>
Date: Thu, 12 Jul 2007 15:43:26 -0400
Errors-To: owner-nanog@merit.edu
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owner-nanog@merit.edu wrote on 07/12/2007 02:07:00 PM:
> Typical Problem Scenario: Data transmission is humming along
> consistently at 2 Mbps, all of a sudden transmission rates drop to
> nothing then pickup again after 15-20 seconds. Prior to the drop off
> (based on packet capture) there is usually a DUP ACK/SACK coming
> from the receiver followed by the Retransmits and congestion
> avoidence. What is strange is there is nothing prior to the drop off
> that would be an impetus for congestion (no high BW utilization or
> packet loss).
Perhaps you're filling buffers by flowing from a 1Gbps link into a 9Mbps
circuit. Dropped packets induces slow-start/congestion avoidance.
Joe
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<br><font size=2><tt>owner-nanog@merit.edu wrote on 07/12/2007 02:07:00
PM:<br>
<br>
> Typical Problem Scenario: Data transmission is humming along <br>
> consistently at 2 Mbps, all of a sudden transmission rates drop to
<br>
> nothing then pickup again after 15-20 seconds. Prior to the drop off<br>
> (based on packet capture) there is usually a DUP ACK/SACK coming <br>
> from the receiver followed by the Retransmits and congestion <br>
> avoidence. What is strange is there is nothing prior to the drop off<br>
> that would be an impetus for congestion (no high BW utilization or
<br>
> packet loss).<br>
</tt></font>
<br><font size=2><tt>Perhaps you're filling buffers by flowing from a 1Gbps
link into a 9Mbps circuit. Dropped packets induces slow-start/congestion
avoidance.</tt></font>
<br>
<br><font size=2><tt>Joe</tt></font>
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