Open Stack

Hey, all.  Trying to set up Dibbler/IPv6 prefix delegation on a Newton 
Ubuntu cloud.  And I admit that I'm being somewhat confused, despite One 
Bajillion Pages that seem to touch on this stuff, but not really map out 
what needs to happen.  (Most of the step-throughs seem to assume 
single-box installs a la Devstack, which isn't quite as helpful for 
something like this.)

What I'm looking to do (unless someone says "That's stupid," and 
suggests a better way):

[External Dibbler] <---> [Neutron Gateway] <---> [Openstack cloud]

As I understand it, I need to set ipv6_pd_enabled to "true" in the 
neutron.conf file -- though I'm not sure if that's on the Neutron API 
server, or the Neutron Gateway, itself.  Additionally, Ubuntu doesn't 
help, because it's not supported by Juju.  (At least, as of Newton.)

So:
* Where do I modify the neutron.conf file (API or gateway)?
* How do I tell Openstack about where the Dibbler server is?
* What subnet configuration should I employ?
* What would a typical network creation look like in such a 
circumstance?
* Am I missing anything really dumb/stupid?

Thanks kindly,

-Ken