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Date:      Sun, 31 Dec 2000 18:03:13 -0500
From:      csg@waterspout.com (C. Stephen Gunn)
To:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Cc:        "C. Stephen Gunn" <csg@waterspout.com>, Andrea Franceschini <andrea@cs.tin.it>, Ferdinand Goldmann <ferdl@atommuell.oeh.uni-linz.ac.at>, "freebsd-net@FreeBSD.ORG" <freebsd-net@FreeBSD.ORG>
Subject:   Re: Problems with VLAN and natd. 
Message-ID:  <200012312258.RAA53006@tsunami.waterspout.com>
In-Reply-To: Your message of "Sun, 31 Dec 2000 15:33:36 EST." <200012312033.PAA08488@khavrinen.lcs.mit.edu> 

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On Sun, 31 Dec 2000 15:33:36 EST, Garrett Wollman wrote:

> Actually, no, it's not what you want (although the underlying code is
> broken enough to let it ``work'' anyway).  What you want is to fix the
> parent network interface driver to indicate its readiness to receive
> 1522-octet frames by setting its if_data.ifi_hdrlen field to 18 rather
> than 14.

Garrett is correct.  My confirmation was intended to tell you it
would work, not that you're in an ideal situation.  Then again, you're
applying miscellaneous patches to your ethernet drivers to get vlans
to work, so you're probably aware you're in the weeds.

I'm not sure that the solution is simply a fix to the parent ethernet
device driver, since it's legitimate (but perhaps not advisable)
to have tagged and untagged frames on the same wire.  Setting the
ifi_hdrlen for the entire physical interface seems incomplete also.

The current VLAN (and Ethernet) implementaiton in FreeBSD needs work.
FreeBSD should should handle multiple ethernet encapsulations on
the same physical interface, and relay packets to/from some subordinate
interface.  This support would factor-out the need for current 
work-arounds like if_vlan, and if_ef, and perhaps even if_tap.

 - Steve

--
C. Stephen Gunn                          URL: http://www.waterspout.com/
WaterSpout Communications, Inc.        Email: csg@waterspout.com
427 North 6th Street                   Phone: +1 765.742.6628
Lafayette, IN  47901                     Fax: +1 765.742.0646


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