SPs and large enterprises have distinct organizations with separate budgets and head count that focus on the IT/Data Center and the Network respectively. SDN looks to migrate networking functions to the data center to leverage general purpose hardware (see previous post). Who's going to pay for the solution? Who's going to manage the solution? These issues may appear trivial and solvable and in an ideal world they are. But in reality, these questions must be address and a deployment scenario that satisfies each of these organizations must be created.
An historical example was the combination of a Class 5 switch POTS card and a DSL modem. Sounded great, simplified wiring, simplified management etc. However, the technologist behind this initiative failed to recognize that the purchasers of the POTS card and the purchases of the DSL modems were in different organizations and in the US were legal prohibited from joint purchases.