From owner-freebsd-net@FreeBSD.ORG Thu Apr 17 17:40:18 2003 Return-Path: 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 C905637B401 for ; Thu, 17 Apr 2003 17:40:18 -0700 (PDT) Received: from odin.ac.hmc.edu (Odin.AC.HMC.Edu [134.173.32.75]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2C9B543FD7 for ; Thu, 17 Apr 2003 17:40:18 -0700 (PDT) (envelope-from brdavis@odin.ac.hmc.edu) Received: from odin.ac.hmc.edu (IDENT:brdavis@localhost.localdomain [127.0.0.1]) by odin.ac.hmc.edu (8.12.9/8.12.3) with ESMTP id h3I0eATk029668; Thu, 17 Apr 2003 17:40:11 -0700 Received: (from brdavis@localhost) by odin.ac.hmc.edu (8.12.9/8.12.3/Submit) id h3I0eAXP029667; Thu, 17 Apr 2003 17:40:10 -0700 Date: Thu, 17 Apr 2003 17:40:10 -0700 From: Brooks Davis To: Mike Tancsa Message-ID: <20030418004010.GA25152@Odin.AC.HMC.Edu> References: <16031.17219.159093.279782@canoe.velocet.net> <16031.17219.159093.279782@canoe.velocet.net> <5.2.0.9.0.20030417202920.07adb1e0@marble.sentex.ca> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="qMm9M+Fa2AknHoGS" Content-Disposition: inline In-Reply-To: <5.2.0.9.0.20030417202920.07adb1e0@marble.sentex.ca> User-Agent: Mutt/1.5.4i X-Virus-Scanned: by amavisd-milter (http://amavis.org/) on odin.ac.hmc.edu cc: freebsd-net@freebsd.org Subject: Re: vlan0 on em0 has mtu 1496 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Apr 2003 00:40:19 -0000 --qMm9M+Fa2AknHoGS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 17, 2003 at 08:34:47PM -0400, Mike Tancsa wrote: > At 05:19 PM 17/04/2003 -0700, Brooks Davis wrote: > >On Thu, Apr 17, 2003 at 08:13:55PM -0400, David Gilbert wrote: > >> Why does a vlan created against em0 have a mtu of 1496. > > > >Because the vlan header takes up 4 bytes. With em(4) devices it looks > >like fixing that should be a simple matter of raising the real > >interface's MTU to 1504. >=20 > Why the difference in behavior vs how the fxp driver works with respect t= o=20 > vlans ? I don't know. In current both have the VLAN_MTU capability set, but I don't seem to be getting consistant results from 4.x systems. -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --qMm9M+Fa2AknHoGS Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQE+n0loXY6L6fI4GtQRAnCSAKDLR+0kQYdY9/blLt83sdiKRtCquwCfaJQ8 /m0rHi8ui0o3oYXHI2rYx1w= =nEOg -----END PGP SIGNATURE----- --qMm9M+Fa2AknHoGS--