]) by chopin.merit.edu (MOS 3.8.2-GA) with ESMTP id AFJ77356; Thu, 12 Jul 2007 16:09:26 -0400 (EDT) Received: (from steve@localhost) by mrserver.telecomplete.net (8.13.8/8.13.8/Submit) id l6CK9OU0013476; Thu, 12 Jul 2007 21:09:24 +0100 Date: Thu, 12 Jul 2007 21:09:24 +0100 From: Stephen Wilcox <steve.wilcox@packetrade.com> To: Philip Lavine <source_route@yahoo.com> Cc: nanog <nanog@merit.edu> Subject: Re: TCP congestion Message-ID: <20070712200924.GC8520@MrServer.telecomplete.net> References: <352820.35037.qm@web30813.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <352820.35037.qm@web30813.mail.mud.yahoo.com> User-Agent: Mutt/1.4.2.2i Sender: owner-nanog@merit.edu Precedence: bulk Errors-To: owner-nanog@merit.edu X-Loop: nanog X-Junkmail-Status: score=10/50, host=mozart.merit.edu X-Junkmail-SD-Raw: score=unknown, refid=str=0001.0A090206.46968B71.005A:SCGAP167720,ss=1,fgs=0, ip=198.108.1.26, so=2006-09-22 03:48:54, dmn=5.3.14/2007-05-31 Status: RO X-Status: X-Keywords: NonJunk X-UID: 18 Well, if its out of order its the same as if its lost or delayed, it needs to se e that missing segment before the window is full As mentioned you need to get dumps from both ends, you will almost definitely fi nd that you have packet loss which tripped tcp's slow start mechanism. Steve On Thu, Jul 12, 2007 at 12:02:49PM -0700, Philip Lavine wrote:

Even if the segment was received out of order what would cause congestion avoi

dance to starve the connection of legitimate traffic for 15 to 20 seconds? That is the core of the problem.

----- Original Message ---- From: Fred Baker <fred@cisco.com> To: Brian Knoll <Brian.Knoll@tradingtechnologies.com> Cc: Philip Lavine <source_route@yahoo.com>; nanog <nanog@merit.edu> Sent: Thursday, July 12, 2007 11:56:06 AM Subject: Re: TCP congestion

On Jul 12, 2007, at 11:42 AM, Brian Knoll ((TTNET)) wrote:

...

If the receiver is sending a DUP ACK, then the sender either never received the first ACK or it didn't receive it within the timeframe it expected.

or received it out of order.

Yes, a tcpdump trace is the first step.

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