From owner-freebsd-net Tue Oct 26 16:58: 1 1999 Delivered-To: freebsd-net@freebsd.org Received: from smtp.nwlink.com (smtp.nwlink.com [209.20.130.57]) by hub.freebsd.org (Postfix) with ESMTP id 239221500C for ; Tue, 26 Oct 1999 16:57:56 -0700 (PDT) (envelope-from craigc@nwlink.com) Received: from craigc (ip133.gte8.rb1.bel.nwlink.com [209.20.237.133]) by smtp.nwlink.com (8.9.3/8.9.3) with SMTP id QAA09715; Tue, 26 Oct 1999 16:57:54 -0700 (PDT) Message-ID: <1f6601bf200e$c8e476b0$0201010a@fuzzer.com> From: "Craig Critchley" To: "Garrett Wollman" , References: <1df701bf1f84$32751020$0201010a@fuzzer.com> <199910261606.MAA83232@khavrinen.lcs.mit.edu> Subject: Re: FTP Net Performance Date: Tue, 26 Oct 1999 17:04:05 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2314.1300 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Thanks. I guess I need to track down the thesis and give it a read - the graphs themselves are relatively uninteresting - flat lines at large negative numbers. (This is a small enough network that I can make sure there is more or less nothing else happening when I try to FTP something.) I got conflicting suggestions from a couple people about whether to use full or half-duplex. The device defaults to half-duplexing, which seems to be correct for a hub (the two machines do not have the switch between them as they are both on the 100Mb segment). I'm not too concerned about 50Mb vs. 100Mb, or even 10Mb vs. 100Mb - I'm getting barely 100kilobits. Three orders of magnitude difference. But uploading to the BSD machine goes full speed. (For the record, ifconfig and the hub blinkies agree that I have a 100Mb link.) Looking at netstat -i, I see that I'm getting Oerrs of about 15% of Opkts, but no Ierrs. There is an inconsequential number of collisions. Perhaps the error rate is to blame for the problem. What sorts of things do these errors represent? Thanks, ...Craig ----- Original Message ----- From: Garrett Wollman To: Craig Critchley Cc: Sent: Tuesday, October 26, 1999 9:06 AM Subject: FTP Net Performance > < said: > > > Any suggestions profoundly appreciated. > > Whenever TCP behaves strangely, your first step should be to capture a > trace with tcpdump(8) and use tcpdump2xplot.pl and xplot(1) (part of > /usr/ports/math/xplot) to see what's going on. The visual analysis > technique is developed in Tim Shepard's S.M. thesis, references to > which are available in the xplot tarball. > > -GAWollman > > -- > Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same > wollman@lcs.mit.edu | O Siem / The fires of freedom > Opinions not those of| Dance in the burning flame > MIT, LCS, CRS, or NSA| - Susan Aglukark and Chad Irschick > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message