From owner-freebsd-net  Thu Feb  3 12:29:36 2000
Delivered-To: freebsd-net@freebsd.org
Received: from khavrinen.lcs.mit.edu (khavrinen.lcs.mit.edu [18.24.4.193])
	by builder.freebsd.org (Postfix) with ESMTP id 8A4BE3DE5
	for <freebsd-net@FreeBSD.ORG>; Thu,  3 Feb 2000 12:29:33 -0800 (PST)
Received: (from wollman@localhost)
	by khavrinen.lcs.mit.edu (8.9.3/8.9.3) id PAA63379;
	Thu, 3 Feb 2000 15:25:32 -0500 (EST)
	(envelope-from wollman)
Date: Thu, 3 Feb 2000 15:25:32 -0500 (EST)
From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Message-Id: <200002032025.PAA63379@khavrinen.lcs.mit.edu>
To: "Matthew N. Dodd" <winter@jurai.net>
Cc: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>,
	"Pedro J. Lobo" <pjlobo@euitt.upm.es>, freebsd-net@FreeBSD.ORG
Subject: Re: 802.1Q VLANs
In-Reply-To: <Pine.BSF.4.21.0002031454550.479-100000@sasami.jurai.net>
References: <200002031847.NAA62013@khavrinen.lcs.mit.edu>
	<Pine.BSF.4.21.0002031454550.479-100000@sasami.jurai.net>
Sender: owner-freebsd-net@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org

<<On Thu, 3 Feb 2000 15:04:29 -0500 (EST), "Matthew N. Dodd" <winter@jurai.net> said:

> Humm...  Isn't this going to confuse BPF when its receiving normal
> ethernet headers?

No.  If it's listening on the vlan interface, it will get the
decapsulated packets.  If it's listening on the master interface, it
will get everything.  tcpdump, at least, understands (or can easily be
made to understand) 802.1Q tagging.  The libpcap filter compiler
doesn't actually know about 802.1Q, but it doesn't know about
ifi_hdrlen either!

This is important as a debugging facility.

> I'm not sure we want to have the drivers always accept large
> packets, just because we've compiled a kernel with VLAN devices in it.

Not because we've compiled a kernel with VLAN devices in it; because
we've compiled a kernel with a NIC driver that supports large packets.

-GAWollman



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message