Proxying RPC over unix domain socket between two Linux netns.
Some openstack features are implemented in instance VM(s). So it is necessary for openstack-servers like neutron-server need to issue RPC from openstack management network into openstack tenant networks which is strictly isolated. So there needs some way to proxy RPC between openstack management network and tenant networks. This is a requirement for servicevm framework for neutron https://blueprints.launchpad.net/neutron/+spec/adv-services-in-vms
One possible(and proposed) way is to use unix domain socket to relay RPC messages.