From owner-freebsd-questions@FreeBSD.ORG Tue Feb 9 13:14:04 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D582A106566B for ; Tue, 9 Feb 2010 13:14:04 +0000 (UTC) (envelope-from h.schmalzbauer@omnilan.de) Received: from host.omnilan.net (host.omnilan.net [62.245.232.135]) by mx1.freebsd.org (Postfix) with ESMTP id 44A678FC17 for ; Tue, 9 Feb 2010 13:14:03 +0000 (UTC) Received: from titan.flintsbach.schmalzbauer.de (titan.flintsbach.schmalzbauer.de [172.21.1.150]) (authenticated bits=0) by host.omnilan.net (8.13.8/8.13.8) with ESMTP id o19DCleH044688 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 9 Feb 2010 14:12:48 +0100 (CET) (envelope-from h.schmalzbauer@omnilan.de) Message-ID: <4B715F4F.4030401@omnilan.de> Date: Tue, 09 Feb 2010 14:12:47 +0100 From: Harald Schmalzbauer Organization: OmniLAN User-Agent: Thunderbird 2.0.0.23 (X11/20090906) MIME-Version: 1.0 To: Ilya Zhuravlev References: <4B715125.8070809@omnilan.de> <4B7153A3.3000002@cbtnet.ru> In-Reply-To: <4B7153A3.3000002@cbtnet.ru> X-Enigmail-Version: 0.95.6 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig93B013FAA4CF5CEAD811FAF6" Cc: freebsd-questions@freebsd.org Subject: Re: MTU, fragmentation and Jumbo Frames question X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Feb 2010 13:14:04 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig93B013FAA4CF5CEAD811FAF6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Ilya Zhuravlev schrieb am 09.02.2010 13:22 (localtime): > On 09.02.2010 20:12, Harald Schmalzbauer wrote: >> Hello all, >> >> I have 3 machines connected to an JumboFrame enabled switch. >> One FreeBSD 8-stable and two windows machines. >> I can send echo requests with payload of 8972 between the windows >> machines, but I don't get an answer from the FreeBSD machine. At the >> edge of 8130 bytes, the FreeBSD machine eats the packets without any >> error notification. A payload <=3D 8130 bytes works! >> All MTUs are set to 9000, interfaces are all intel em. >> Like mentioned, the ping between the two windows machines work like >> expected, beyond 8972 bytes payload the OS is fragmenting (resp. tells= >> me that DF bit was set but fragmentation was needed) >> FreeBSD seems to never fragment packets, since I don't get an answer i= f >> I define payload greater than MTU. But this should work, shouldn't it >> (`ping -s 10000 host`) >> >> Does anybody have any explanation why pings are working up to 8130 byt= es >> payload and are silently droped beyond that even my MTU ist set to 900= 0 >> (and route get confirms the MTU 9000)? >=20 > kern/143285 > but "ifconfig em0 -rxcsum" is enough for me. Thanks, but disabling any sum offloading doesn't change anything. Still, I wonder why FreeBSD doesn't fragment packets if they're too large= =2E Thanks, -Harry --------------enig93B013FAA4CF5CEAD811FAF6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEARECAAYFAktxX08ACgkQLDqVQ9VXb8iL1QCfQn2JsFyIagKXkCgpHdbx0uT0 Ge4AoLZJuwo4YJQqngaeKxo5hViD2Fud =OO5W -----END PGP SIGNATURE----- --------------enig93B013FAA4CF5CEAD811FAF6--