[VLAN] vlan Q in Q - [WAS Re: Using a switch fabric to emulate multiple NICs]

[ajz at cambridgebroadband.com (Alex Zeffertt)]

On Mon, 25 Jul 2005 14:23:24 -0700
Ben Greear <greearb@xxxxxxxxxxxxxxx> wrote:

> > Secondly you need to be able to make the switch fabric ignore any vlan tags on it's non-MII
> > ports, but use the (outer) tag on its MII port.  I'm pretty sure I can do this on the 88e9095 by
> > re-configuring the DIX type (used to identify tagged frames on the non-MII ports) from 0x8100 to
> > something reserved.  However, I won't know that this will work for sure till I get the eval
> > board.
> 
> You may also have to hack on the VLAN code a bit...I'm not sure it completely supports
> vlans in vlans, though it should be fairly straight-forward to add such support.
> 

Hi Ben,  

You appear to be correct.  I can ping from

	eth0.16 on machine1	to eth0.16 on machine2

but not from
	eth0.16.5 on machine1	to eth0.16.5 on machine 2

But I cannot see why this should be a problem.  As I see it 8021q.o just adds a vlan tag to packets
going down and strips the outer tag on packets going up.  Please can you expand on this.

Regards,

Alex