Source:
https://www.google.com.au/search?q=sdn&biw=1706&bih=825&source=lnms&tbm=isch&sa=X&ei=GevoVO6GLYPc8AXp2YDQAw&ved=0CAgQ_AUoAw&dpr=0.75#tbm=isch&q=software+defined+network&imgdii=_&imgrc=i13mOJVJG4biqM%253A%3B4AVGOm2QJwztoM%3Bhttp%253A%252F%252F2.bp.blogspot.com%252F-laDpnM27IsU%252FUMiQ7PL-XbI%252FAAAAAAAAKyw%252FballHHjhGgQ%252Fs1600%252Fsdn.png%3Bhttp%253A%252F%252Fwww.thetech.in%252F2012%252F12%252Fsoftware-defined-networking-sdn-basics.html%3B362%3B195