"Today, if you buy a networking switch from a large vendor, it's
not easy to modify the software running on it. What SDN enables
switch owners to do is extend the functionality of the network. SDN
also provides open APIs that enables orchestration of applications
on the network.
In Appenzeller's view, for SDN to be successful it requires open
protocols, open APIs and open source code. Appenzeller's startup
company Big Switch Networks is currently in the process of building
a commercial OpenFlow controller.