Comment 5 for bug 1639566

As Kevin said, this has come up time and time again (e.g. bug 1467471), and I have seen many etherpads coming up (e.g. https://etherpad.openstack.org/p/decentralized-snat). The IP per router,compute couple is doable but it burns IP addresses. I suppose with the service-type [1]
extension this issue can be somewhat mitigated, but it was enough to make past proposals to crash and burn.

[1] https://specs.openstack.org/openstack/neutron-specs/specs/newton/subnet-service-types.html