From owner-freebsd-net Thu Aug 3 20:15:27 2000 Delivered-To: freebsd-net@freebsd.org Received: from smtp.whitebarn.com (Spin.WhiteBarn.Com [216.0.13.113]) by hub.freebsd.org (Postfix) with ESMTP id 5826B37B8F5 for ; Thu, 3 Aug 2000 20:15:23 -0700 (PDT) (envelope-from Bob@WhiteBarn.Com) Received: from WhiteBarn.Com (Relent.Bob.WhiteBarn.Com [216.0.13.50]) by smtp.whitebarn.com (8.9.3/8.9.3) with ESMTP id WAA98186; Thu, 3 Aug 2000 22:15:21 -0500 (CDT) (envelope-from Bob@WhiteBarn.Com) Message-ID: <398A3549.902A31F5@WhiteBarn.Com> Date: Thu, 03 Aug 2000 22:15:21 -0500 From: Bob Van Valzah X-Mailer: Mozilla 4.72 [en] (X11; I; FreeBSD 4.0-STABLE i386) X-Accept-Language: en MIME-Version: 1.0 To: freebsd-net@FreeBSD.ORG Subject: VLAN MTU? 1500? 1504? Why? Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org I'm about to try setting up VLANs on FreeBSD. I haven't yet found any mention of VLANs in the FreeBSD documentation. The web pages I've read on the subject seem to indicate that there's some dissension in deciding how hosts with VLAN interfaces should handle the extra 4 bytes required for the VLAN header. One camp seems to be saying that the NIC's idea of MTU for the physical interface should be raised to 1504 to allow room for this header so that the VLAN interfaces can maintain the usual 1500-byte MTU. Another camp seems to feel that the 1500-byte MTU of the physical interface is sacred and suggests that the VLAN interfaces should have an MTU of 1496. What're the pros and cons of each approach? Is there a consensus as to which would be a better default? Thanks, Bob To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message