vlans and cloning

[Robert Watson]

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