SDN is very wide subject - and in the past a headline for a lot of things - functionality of this subject are main components of the extreme solution.
Currently automation and connecting/connect management tools and authentication with other IT components are kindly more important than ever.
If you have Netsight (Extreme Manament Center) and NAC (Extreme Control) than you have the most important components. Regarding which specific feature or functionality you need, some additional licenses are necessary.
I hope this helps. If not - please specify your question.