) by chopin.merit.edu (MOS 3.8.2-GA) with SMTP id AFJ75544; Thu, 12 Jul 2007 15:43:44 -0400 (EDT) X-VirusChecked: Checked X-Env-Sender: jloiacon@csc.com X-Msg-Ref: server-12.tower-171.messagelabs.com!1184269421!7290336!1 X-StarScan-Version: 5.5.12.11; banners=-,-,- X-Originating-IP: [20.137.52.151] Received: (qmail 25947 invoked from network); 12 Jul 2007 19:43:42 -0000 Received: from amer-mta07.csc.com (HELO amer-mta07.csc.com) (20.137.52.151) by server-12.tower-171.messagelabs.com with AES256-SHA encrypted SMTP; 12 Jul 2007 19:43:42 -0000 Received: from amer-gw07.amer.csc.com (amer-gw07.amer.csc.com [20.6.39.243]) by amer-mta07.csc.com (Switch-3.1.6/Switch-3.1.7) with ESMTP id l6CJhtpO 001246; Thu, 12 Jul 2007 15:43:56 -0400 (EDT) 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 Subject: Re: TCP congestion MIME-Version: 1.0 X-Mailer: Lotus Notes Release 6.5.4 March 27, 2005 From: Joe Loiacono <jloiacon@csc.com> Message-ID: <OF24F6577F.3CB4C2F7-ON85257316.006BDA71-85257316.006C55D3@csc.com> Date: Thu, 12 Jul 2007 15:43:26 -0400 X-MIMETrack: Serialize by Router on AMER-GW07/SRV/CSC(Release 7.0.2FP1 HF180|Mar ch 29, 2007) at 07/12/2007 03:42:47 PM, Serialize complete at 07/12/2007 03:42:47 PM Content-Type: multipart/alternative; boundary="=_alternative 006C1B0785257316_=" 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=0001.0A09020B.46968652.005A: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: 16 This is a multipart message in MIME format. --=_alternative 006C1B0785257316_= Content-Type: text/plain; charset="US-ASCII" 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 --=_alternative 006C1B0785257316_= Content-Type: text/html; charset="US-ASCII" <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> --=_alternative 006C1B0785257316_=--