vlan stacking

[Bruce M. Simpson]

Ivan Alexandrovich wrote:
> Hi
>
> I'm wondering is anybody using double vlans ("q-in-q",
> "vlan stacking", any name you like) on production hosts?
> Does it play well with common ethernet device drivers in freebsd
> (concerning the frame size) -  fxp, em, for example?
>
> Looks like that almost nobody mentions q-in-q in freebsd 
> maillists/forums,
> except that nesting ng_vlan can be used to implement it.

I'm sure you or someone else can come up with a creative solution for 
Q-in-Q or arbitrary nesting levels. It's not something I use, so, I pass.

The mainline code doesn't support it without Netgraph; it would be 
necessary to allow vlan(4) to be nested. The ether_input() code demuxes 
802.1q encapsulation but only 1 level. The reason for this is because 
the outer VLAN tag got moved into the mbuf pkthdr structure for 
if_bridge to be able to process it.

I can't comment on the netgraph solution however.

regards
BMS