From owner-freebsd-net Mon Aug 19 16:40:14 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 2530537B401; Mon, 19 Aug 2002 16:40:09 -0700 (PDT) Received: from rwcrmhc51.attbi.com (rwcrmhc51.attbi.com [204.127.198.38]) by mx1.FreeBSD.org (Postfix) with ESMTP id 943AC43E6E; Mon, 19 Aug 2002 16:40:08 -0700 (PDT) (envelope-from julian@elischer.org) Received: from InterJet.elischer.org ([12.232.206.8]) by rwcrmhc51.attbi.com (InterMail vM.4.01.03.27 201-229-121-127-20010626) with ESMTP id <20020819234008.VPVG1746.rwcrmhc51.attbi.com@InterJet.elischer.org>; Mon, 19 Aug 2002 23:40:08 +0000 Received: from localhost (localhost.elischer.org [127.0.0.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id QAA48448; Mon, 19 Aug 2002 16:20:38 -0700 (PDT) Date: Mon, 19 Aug 2002 16:20:37 -0700 (PDT) From: Julian Elischer To: Steve Francis Cc: Jesper Skriver , Jeff Behl , net@freebsd.org Subject: Re: MTU not working? In-Reply-To: <3D617842.4020304@expertcity.com> 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 On Mon, 19 Aug 2002, Steve Francis wrote: > Allow me to respond for Jeff (we work at same place, and have both been > looking this issue) > > ICMP's being blocked are the most common explanation for this - but > this is not the case here. > > tcpdump run on the server system shows the ICMP fragmention required - > DF bit set messages being received, and - the irrefutable proof that it > is not an ICMP filtering issue -the FreeBSD system DOES lower the MTU > for that host's cloned route to the value specified in the ICMP (1420 > in the snippet below). New packets are segmented to sizes <= the new > MTU, but it continues resend the original packet over and over, in the > original 1500 byte size. > > So I still say FreeBSD has broken pMTU-D code. > > This is reproducible at will, so we can collect whatever info anyone > wants. > > Yes tcp needs to forget it ever sent that data, and refactor the entire transmit window. I'd agree this is a bug if it's reproducible by others too. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message