Comment 7 for bug 1518087

Armando certainly makes some good points in comment 6 above, but I still believe their are important use cases that are not adequately addressed solely by pre-deployment validation. These involve ML2 actively rejecting potential port bindings that would otherwise be allowed, when that the semantics implied by the extension attribute values would not be provided by that binding, while each individual MD might otherwise participate in completely valid bindings. I acknowledge its a bit late to try to solve this properly in mitaka, so I thing the best way forward is for myself and others interested to prepare a concrete proposal for the N release.