m [65.199.113.8]) by bach.merit.edu (MOS 3.8.2-GA) with SMTP id ADV41181; Thu, 12 Jul 2007 16:48:43 -0400 (EDT) Received: from chiex01.int.tt.local ([172.17.250.113]) by chigtw01.tradingtechnologies.com (SMSSMTP 4.1.11.41) with SMTP id M200707121 5485228873 ; Thu, 12 Jul 2007 15:48:52 -0500 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: RE: TCP congestion Date: Thu, 12 Jul 2007 15:48:41 -0500 Message-ID: <D4C8D8B144E6DE49AA3FC67557D58733061F40B5@chiex01> In-Reply-To: <796919.42253.qm@web30811.mail.mud.yahoo.com> Thread-Topic: TCP congestion Thread-Index: AcfExJFR3hrwrr66SpawYIutE51lMwAAMoGA References: <796919.42253.qm@web30811.mail.mud.yahoo.com> From: "Brian Knoll \(TTNET\)" <Brian.Knoll@tradingtechnologies.com> To: "Philip Lavine" <source_route@yahoo.com>, "Stephen Wilcox" <steve.wilcox@packetrade.com> Cc: "nanog" <nanog@merit.edu> 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=0001.0A090202.4696967E.0055: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: X-UID: 22 Are you using TCP offloading on your windows box? I have seen issues with that in the past where it was dropping data. Turn it off and see if the issue goes away. =20 Are other the other connections traversing this path seeing the same issues? Still - the only definitive way to solve the problem is by getting captures from both ends. If you can isolate your wan with taps on each side and see packets being dropped, you know it's your ATM circuit. =20 QOS will not help you if you aren't exceeding bandwidth. =20 Thanks, Brian Knoll Senior Network Engineer, TTNET 312-698-6017 desk 312-823-0957 mobile -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Philip Lavine Sent: Thursday, July 12, 2007 3:28 PM To: Stephen Wilcox Cc: nanog Subject: Re: TCP congestion I just don't understand how if there is 1 segment that gets lost how this could translate to such a catastrophic long period of slow-start. How can I minimize the impact of the inevitable segment loss/out of order over a WAN. Is QoS the only option? ----- Original Message ---- From: Stephen Wilcox <steve.wilcox@packetrade.com> To: Philip Lavine <source_route@yahoo.com> Cc: nanog <nanog@merit.edu> Sent: Thursday, July 12, 2007 1:09:24 PM Subject: Re: TCP congestion Well, if its out of order its the same as if its lost or delayed, it needs to see that missing segment before the window is full As mentioned you need to get dumps from both ends, you will almost definitely find 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:
=20 Even if the segment was received out of order what would cause congestion avoidance to starve the connection of legitimate traffic for 15 to 20 seconds? That is the core of the problem. =20 ----- 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 =20 =20 On Jul 12, 2007, at 11:42 AM, Brian Knoll ((TTNET)) wrote: =20
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. =20 or received it out of order. =20 Yes, a tcpdump trace is the first step. =20 =20 =20 =20 =20 =20
________________________________________________________________________ ____________
Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=3Dlist&sid=3D396545469
=20 ________________________________________________________________________ ____________ Pinpoint customers who are looking for what you sell.=20 http://searchmarketing.yahoo.com/