FreeNAS 9 has reached a new level of broken in its handling of network
configuration. Essentially each time a vlan interface is added, or
IP configuration is added, it wipes all existing vlan configurtion
and recreates it from its database.  Worse, when IP addresses/aliases
are removed, it completely shuts off all network interfaces and
re-configures them from scratch. ALL interfaces.  All of them.
Every last one. Even those that are not in scope for the current
modification operation.

So, we now do ALL network manipulation, including create/destroy
vlan operations, behind FreeNAS's back.  As a consequence, FreeNAS's
UI will often not show the actual network configuration - it will only
list those things that have been set up statically through its
interfaces (command line or UI).