Comment 5 for bug 1540512

So, just discussed this in the drivers meeting. I wanted to first clear some things up.

1) The request is not for Nova scheduling to do anything different than it does today. The requirement to aggregate IPs around a host or a rack is a soft one. It is nice to group IP addresses into larger CIDRs so that the routing tables are smaller and not full of thousands of host routes. On the other hand, if one area runs out of IP addresses, a few odd host routes are acceptible. It would be pretty extreme to have nova boot fail because we don't want to add a host route when there is no technical reason we can't. Does that make sense?

2) In general, this depends on deferring IP address assignment until after port binding. This is a common requirement with the routed networks work going on in Neutron. You might be able to start this work without that by using some magic incantation that results in doing IPAM on an already bound port but that wouldn't really be generally useful.

I'd like the submitter to adjust the description to make these things clear. Let's get the spec fleshed out a bit. Given that we can have a port with binding done, what interfaces will need to be touched? I can help you on the spec and then we'll bring this back to the drivers.