One small benefit of this approach is that we don't need to test the bridge interface type. There might be some other simplifications that are possible.

I wonder if we can have a hash map lladdr -> ifp to speed up lookups for bridge which have large quantity members.

Yes, that's probably a good idea. Even a flat array would be better than the linked list; now that the data path is protected by an epoch section, it should be pretty easy to implement resizing.