From owner-freebsd-stable Wed Jul 5 9:58: 3 2000 Delivered-To: freebsd-stable@freebsd.org Received: from mail.polytechnic.edu.na (mail.polytechnic.edu.na [196.31.225.2]) by hub.freebsd.org (Postfix) with ESMTP id DC50637B516 for ; Wed, 5 Jul 2000 09:57:51 -0700 (PDT) (envelope-from tim@polytechnic.edu.na) Received: from ns1.horizon.na ([196.31.225.199] helo=polytechnic.edu.na) by mail.polytechnic.edu.na with esmtp (Exim 3.02 #2) id 139uLd-0006EO-00; Wed, 05 Jul 2000 16:56:37 -0200 Message-ID: <396368C9.C3C5A50F@polytechnic.edu.na> Date: Wed, 05 Jul 2000 17:56:41 +0100 From: Tim Priebe Reply-To: tim@iafrica.com.na X-Mailer: Mozilla 4.7 [en] (X11; I; FreeBSD 3.4-RELEASE i386) X-Accept-Language: en MIME-Version: 1.0 To: Luigi Rizzo Cc: David Gilbert , tim@iafrica.com.na, Kevin Oberman , "Louis A. Mamakos" , Joerg Micheel , freebsd-stable@FreeBSD.ORG Subject: Re: Ethernet MTUs > 1500? References: <200007051516.RAA77416@info.iet.unipi.it> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Luigi Rizzo wrote: > > > Kevin> Louis has it exactly right. 802.3 was modified a couple of > > Kevin> years ago to allow for a maximum frame size of 1522 octets, up > > Kevin> from the original 1518. This was to allow the VLAN information > > Kevin> to fit in the frame. > > just curious, what do we do when we have multiple encapsulation ? > (i.e. is this allowed ?) > > cheers > luigi I am not sure what you mean. If you mean "VLAN encapsulation", then it is a misunderstanding. The standard Ethernet frame is not encapsulated. The Ethernet header is modified. The extra 4 Bytes are not at the begining of the frame. The frame is identical to one with prioratization, 12 of the bits indicate the VLAN, and 4 the prority. So there is only one VLAN value, and one priority value possible per frame. Tim. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message