From owner-freebsd-net Sun Nov 3 20:37:25 2002 Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 82FD037B401 for ; Sun, 3 Nov 2002 20:37:24 -0800 (PST) Received: from mail.smashpow.com (mail.smashpow.net [216.235.9.194]) by mx1.FreeBSD.org (Postfix) with ESMTP id 612A543E3B for ; Sun, 3 Nov 2002 20:37:23 -0800 (PST) (envelope-from drek@smashpow.net) Received: from mail.smashpow.net (mail.smashpow.net [216.235.9.194]) by mail.smashpow.com (Postfix) with ESMTP id A9C5722C for ; Sun, 3 Nov 2002 23:37:16 -0500 (EST) Date: Sun, 3 Nov 2002 23:37:16 -0500 (EST) From: Agent Drek To: net@freebsd.org Subject: MTU problems ... Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org hi, I'll start this off by claiming ignorance about the deep inner workings of tcp/ip. As such, this is not going to be a really technically detailed report. I will be more than happy to provide any info that might help in tracking this problem down though! The problem manifests as large downloads hanging (ftp/http/scp). The only way to make a download work is to choose an MTU setting on tun0 (this is a pppoe session) of the FreeBSD server (currently 4.6.2-Rel) until I find a value (1452, 1460, most things work at 1492 though) that makes the download complete properly. Sometimes finding an MTU that works is just not possible. The only icmp rule in ipfw is to allow all icmp so I am not unwittingly disallowing anything important. Could this thread be related to my problem? and was there any resolution with this? http://www.freebsd.org/cgi/getmsg.cgi?fetch=61954+0+/usr/local/www/db/text/2002/freebsd-net/20020825.freebsd-net According to my ISP (and a few other ISP's in the area) only FreeBSD systems and certain IOS versions are experiencing this problem. What can I do to start debugging this? Please CC me as I am not subscribed to net@. cheers, -- Derek Marshall Smash and Pow Inc > 'digital plumber' http://www.smashpow.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message