Comment 8 for bug 1046766

@Ian the entire VIF class mechanism is horribly over-engineering the whole problem, and harming maintainability/flexibility of Nova virt driver development. If you look at possible hypervisor configuration options, there are a merely handful of supportable ways to attach a VM's VIF to a host network (traditional bridge, openvswitch bridge, macvtap - 802.Qbh/Qbg). We do not need to implement a multitude of classes to deal with that. All we need is to define a set of standardized metadata that tells a hypervisor how to connect a VIF to a host network, and for each quantum plugin figure out which attachment is applicable. If we define the metadata then there is no need for any VIF class/subclass mechanism, since the virt drivers can just process the metadata directly.