[VLAN] broadcasts go where?

[James Harper]

> I have a single ethernet card configured as eth0. I also have many
> vlans on it, eth0.1, eth0.2, etc. All of them have the same IP and
> netmask. The choice of interface through which to send packets is done
> by routing:
> 
>   IP     iface
>   1      eth0.4
>   2      eth0.10
>   3      eth0.1
>   4      eth0
> 
> etc. The default route is eth0.
> 
> When I send a broadcast will it go to all vlans or only to eth0?

I assume you have done some policy routing stuff to make the routing
work? That should be a clue that what you have done is a bit of a hack.
This is not really a vlan related problem, the problem you have would
occur even if they were separate physical network adapters.

You need to either:
1. bridge all the vlans together (and use netfilter to stop packets
being forwarded between segments if that's what you are trying to
achieve)
2. break them all up into separate networks (different ip address
ranges)

I think #2 is the more correct solution, but you haven't described
enough about what you are doing and why to be sure.

James