Everything old is new again :-) I read through the SDN specs and thought "Hmm, this reads like they are trying to implement ATM, badly." But one of the really fun things is that nearly all of the switching fabric patents from DEC/Tandem/Etc. from the 90's are evaporating and so we can actually build something like ATM now without getting bogged down in that mess. Because of that I'm pretty optimistic that it will make things a bit better than they were.