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Date:      Tue, 11 Jul 2006 23:51:49 +0100 (BST)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        Brooks Davis <brooks@one-eyed-alien.net>
Cc:        Andre Oppermann <andre@freebsd.org>, Andrew Thompson <thompsa@freebsd.org>, freebsd-arch@freebsd.org
Subject:   Re: vlans and cloning
Message-ID:  <20060711234931.P14749@fledge.watson.org>
In-Reply-To: <20060711162953.GC20418@odin.ac.hmc.edu>
References:  <44B15511.206@errno.com> <44B21551.5050002@freebsd.org> <20060710160441.GB31026@odin.ac.hmc.edu> <20060710202714.GC16054@heff.fud.org.nz> <20060711162953.GC20418@odin.ac.hmc.edu>

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On Tue, 11 Jul 2006, Brooks Davis wrote:

>>> Unless cause ifconfig to autoload all if_ modules when cloning fails, it's 
>>> impossiable to support this without having if_vlan loaded.  That said the 
>>> current plan it to eliminate if_vlan and integrate vlan support directly 
>>> into if_ethersubr.c to allow use to correctly handle the default vlan case 
>>> among otherthings.
>>
>> Is anyone working on this? The bridge code needs access to the vlan tag to 
>> properly hash the address as each vlan is a seperate broadcast domain, this 
>> would be much easier with vlan merged to if_ethersubr.c.
>
> I think it ended up with Robert's name on it at the last devsummit, but he's 
> got a lot of higher priority stuff on his plate.  It doesn't look like this 
> change would be all that much work.  The one thing that might be worth 
> investigating is seeing if there's a sane way to make vlan tag parsing part 
> of ether_input, but keep if_vlan.c around as a module for actual support of 
> trunks so we get most of the architectural benefits of correctly treating 
> vlan tags as part of the spec, but let embedded users who don't need trunks 
> avoid the overhead.

Yes -- the specific proposal I have made is that we combine if_vlan.c into 
if_ethersubr.c, as well as LLC encapsulation decapsulation.  Vlans and LLC 
bits are all considered standard ethernet features today, and integrating the 
basic support (regardless of virtual interfaces) into if_ethersubr.c makes 
sense.  It would also make the book keeping and event handling go a bit more 
naturally, I think.  I've not had a chance to prototype this to explore what 
the above words actually mean, so I think some experimental prototyping is 
called for.  It's on my todo list but something I'm likely not to get to for a 
few months, so if someone else wants to look into this, I think that would be 
great.

Robert N M Watson
Computer Laboratory
University of Cambridge



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