From owner-freebsd-net@FreeBSD.ORG Sun Jan 25 18:09:46 2009 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 617151065670 for ; Sun, 25 Jan 2009 18:09:46 +0000 (UTC) (envelope-from sandiegobiker@gmail.com) Received: from rv-out-0506.google.com (rv-out-0506.google.com [209.85.198.239]) by mx1.freebsd.org (Postfix) with ESMTP id 38DD68FC13 for ; Sun, 25 Jan 2009 18:09:46 +0000 (UTC) (envelope-from sandiegobiker@gmail.com) Received: by rv-out-0506.google.com with SMTP id b25so5647575rvf.43 for ; Sun, 25 Jan 2009 10:09:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:date:message-id:subject :from:to:content-type:content-transfer-encoding; bh=HL43Ppy7b8WjMVf8siKDOF1SESXT6Z9y4EMLlYj8Nzk=; b=LcS3nI+S7GdKvxRkqTOjPdv8txdjxbHY20ySOL5hChMn+mP0fKeF50/inWCdu2intl ejOSWghSTT6g/ziCDb4Lqx/TFj1pesXhLsiFZYsnDg0LYj6p+Vt3mZho5i0zwOnw9Jw1 Tp+inlxWaKbOFc0cXCjFk1L9E3DA0AJhl1QEY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type :content-transfer-encoding; b=cjViuIcxZ1x5xYCrXB4wpjIremfgXPQGkF/LvkyxJhv0Vm78IFpwa6VeF7GYw1hSvr EPS4xCDRDU3lyhicsJmnOJA3F+e3CrSHcMEcxjtPrAt71jHtZTDQSFJVcDblsrD/fhlN syXbt2uPockU9A9EHUoDoKv+jwgRQkc1Zw8oo= MIME-Version: 1.0 Received: by 10.141.107.13 with SMTP id j13mr6366752rvm.141.1232906985727; Sun, 25 Jan 2009 10:09:45 -0800 (PST) Date: Sun, 25 Jan 2009 10:09:45 -0800 Message-ID: <27cb3ada0901251009x7a96019am672f8bd42380df90@mail.gmail.com> From: Len Gross To: "freebsd-net@freebsd.org" Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Subject: MTU or Fragmentation Problems on 7.0? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Jan 2009 18:09:46 -0000 The following configuration works fine _until_ I make a change in MTU setting on the link between FreeBSD1 and FreeBSD2 Internet | Router x.x.x.x 192.168.0.1/16 | FreeBSD #1 192.168.0.202 /16 6.3 192.168.1.1/ 24 | FreeBSD #2 192.168.1.2/24 =09 7.0 192.168.1.5/24 | FreeBSD #3 192.168.5.2/24 7.0 All connections are Ethernet. If I change the MTU on 192.168.1.1 to 1450 and the corresponding MTU on 192.168.1.2 to 1450, then Web Browsing on FreeBSD2 continues to work, BUT browsing on FreeBSD3 "fails" (mostly.) On FreeBSD 3 Ping and nslookup work fine from FreeBSD3 I can get to Google but virtually no other web sites Using tcpdump there is lots of unusual stuff, some relating to fragmentation ICMP? If I put a Web Proxy on FreeBSD 1, everything works fine. I have tried putting mtu =3D 1450 using route change on all the routes, but that didn't help. When I did this I verified all routes had 1450 mtu via netstat =96arW So I am unsure if this is a FreeBSD bug, a "internet" fragmentation issue o= r ??? Amongst the strangest things is that FreeBSD 2 is unaffected; Firefox runs fine there (There was a thread in October about mtu issues in 7.0 but it didn't seem to help my problem.) (I run 1450 MTU to support testing of an experimental protocol., but all the above is with straight out of the box FreeBSD.) -- Len