rate-limiting is the same as in router configuration. When you connect to the internet, the ISP uses this method to limit your speed according to your subscription. This can control the speed and adds delay. In SDN they have the same capabilities. In switch they can be implimented in port bases. However with the addition of SDN overhead, the requiered values are not achieved 100%. More delay will be added.
Open Flow rate has a basic but strong metering mechanism.
If flow crosses the meter a configured action takes place, where the action can be discard or increasing drop precedence. It is simple to emulate 2-threshold WRED.
However, there is no shaping mechanism as in carrier grade Ethernet switches, which enforces a rate cap by smoothly delaying packets rather than discarding them.
I basically agree with Yaakov. However, what he states is not achieved by all vendors. I therefore recommend to go through the manuals and make a couple of "certification" tests with the real device before it hurts your pocket ;-) Mileage DOES vary...