From owner-freebsd-stable Mon Jul 3 21:37:54 2000 Delivered-To: freebsd-stable@freebsd.org Received: from sabre.velocet.net (sabre.velocet.net [198.96.118.66]) by hub.freebsd.org (Postfix) with ESMTP id 831E437BA98 for ; Mon, 3 Jul 2000 21:37:50 -0700 (PDT) (envelope-from dgilbert@office.tor.velocet.net) Received: from office.tor.velocet.net (trooper.velocet.net [216.126.82.226]) by sabre.velocet.net (Postfix) with ESMTP id 0DFB4137FD2; Tue, 4 Jul 2000 00:37:46 -0400 (EDT) Received: (from dgilbert@localhost) by office.tor.velocet.net (8.9.3/8.9.3) id AAA43810; Tue, 4 Jul 2000 00:37:45 -0400 (EDT) (envelope-from dgilbert) From: David Gilbert MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14689.27160.907313.347624@trooper.velocet.net> Date: Tue, 4 Jul 2000 00:37:44 -0400 (EDT) To: "Louis A. Mamakos" Cc: David Gilbert , Joerg Micheel , freebsd-stable@FreeBSD.ORG Subject: Re: Ethernet MTUs > 1500? In-Reply-To: <200007040353.XAA03131@whizzo.transsys.com> References: <14689.22689.894466.908666@trooper.velocet.net> <20000704153914.C60136@cs.waikato.ac.nz> <14689.23903.87264.511506@trooper.velocet.net> <200007040353.XAA03131@whizzo.transsys.com> X-Mailer: VM 6.75 under 20.4 "Emerald" XEmacs Lucid Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >>>>> "Louis" == Louis A Mamakos writes: Louis> There's some confusion here, because the MTU is typically Louis> associated with a protocol stack like IP and refers to the Louis> largest sized (IP in this case) packet that can be sent on the Louis> network interface. In the case of Ethernet interfaces that Louis> support and use VLAN tags, the MTU is still 1500 bytes, Louis> regardless of the fact that the frame size is a few bytes Louis> longer to accomodate the VLAN tag information. Louis> So, this has no effect on the Ethernet type field (or 802.3 Louis> length fields) since the higher level protocol packet size is Louis> unchanged. Why, then, are the vlan MTUs hardwired at 1496? Dave. -- ============================================================================ |David Gilbert, Velocet Communications. | Two things can only be | |Mail: dgilbert@velocet.net | equal if and only if they | |http://www.velocet.net/~dgilbert | are precisely opposite. | =========================================================GLO================ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message