From owner-freebsd-net Mon Aug 12 17:30:46 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 ED01337B400 for ; Mon, 12 Aug 2002 17:30:43 -0700 (PDT) Received: from 66-162-33-178.gen.twtelecom.net (66-162-33-178.gen.twtelecom.net [66.162.33.178]) by mx1.FreeBSD.org (Postfix) with ESMTP id A8EAA43E3B for ; Mon, 12 Aug 2002 17:30:43 -0700 (PDT) (envelope-from jeff@expertcity.com) Received: from [10.4.1.134] (helo=expertcity.com) by 66-162-33-178.gen.twtelecom.net with esmtp (Exim 3.22 #4) id 17ePa7-0001qh-00 for net@freebsd.org; Mon, 12 Aug 2002 17:30:43 -0700 Message-ID: <3D585310.8010709@expertcity.com> Date: Mon, 12 Aug 2002 17:30:08 -0700 From: Jeff Behl User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.4.1) Gecko/20020314 Netscape6/6.2.2 X-Accept-Language: en-us MIME-Version: 1.0 To: net@freebsd.org Subject: MTU not working? Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit 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 We're seeing something odd that is seriously impacting our service for some clients. Even though a the box seems to have the correct MTU in the routing table, it doesn't seem to follow it in all cases. dell350-12.snv#sysctl -a | grep mtu net.inet.tcp.path_mtu_discovery: 1 dell350-12.snv#uname -a FreeBSD dell350-12.snv 4.4-RELEASE FreeBSD 4.4-RELEASE #0: Fri Aug 2 03:24:36 PDT 2002 root@dell350-12.snv:/usr/src/sys/compile/COMMS44-2 i386 dell350-12.snv#netstat -rnal | grep 10.4.1.134 10.4.1.134 63.xxx.224.129 UGHW 1 2268 1420 fxp0 but tcpdump shows: 17:21:43.497275 63.xxx.224.154.80 > 10.4.1.134.2314: . 1:1461(1460) ack 248 win 17520 (DF) 17:21:51.497212 63.xxx.224.154.80 > 10.4.1.134.2314: . 1:1461(1460) ack 248 win 17520 (DF) 17:22:07.497065 63.xxx.224.154.80 > 10.4.1.134.2314: . 1:1461(1460) ack 248 win 17520 (DF) obviosly the packet isn't making it back to the client as it's too big. any ideas? I don't see any bug reports on it. We believe the same situation exsits with a 4.6 server but I haven't checked that thorougly enough yet. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message