Comment 5 for bug 1846285

After looking at the detailed implementation of routed_network, I saw biggest challenge is to change current subnet/segment schema.

Now subnet has only one segment_id, and for this concept we have to change this 1:1 mapping to 1:N. To be specific, one subnet should have as many segments as the number of hypervisors.

DHCP agents for this architecture should be scheduled not only using segment bound subnets but also bound host_id. What I had made about distributed DHCP agent would be invalid since after that we actually changed agent notifier RPC.

I expect Neutron guys are already familiar with this approach, but for whom does not I leave some reference of this architecture for better understanding.

- https://engineering.linecorp.com/en/blog/verda-at-cloudnative-openstack-days-2019-2-2/
- https://netdevconf.info/1.2/slides/oct7/09_andrew_kong_netdefconf_2016.pdf
- http://info.tigera.io/rs/805-GFH-732/images/ProjectCalico-Datasheet.pdf