bridge networking isolation for domus on the dom0

["STEPHEN JONES, W0TTY" <smj%cirr.com@localhost>]

I've scanned through the list archives and found some messages  
touching on this.  I
have a limited number of IPs all on the same network and would like  
to setup rules
on the Dom0 to isolate the Domus from each other.  My only option in  
the configuration
is to do routing on the dom0 itself.