if_bridge as if_vlan parent

[Tom Judge]

Hi,

I was why I get the following error when trying to create a vlan on top 
of if_bridge:

# ifconfig bridge0 create
# ifconfig vlan2 vlan 2 vlandev bridge0
ifconfig: SIOCSETVLAN: Protocol not supported


And if there was/is any reason for this to not be supported.

Thanks

Tom