+ <p>
+ OpenFlow controller set. If unset, then no OpenFlow controllers
+ will be used.
+ </p>
+
+ <p>
+ If there are primary controllers, removing all of them clears the
+ flow table. If there are no primary controllers, adding one also
+ clears the flow table. Other changes to the set of controllers, such
+ as adding or removing a service controller, adding another primary
+ controller to supplement an existing primary controller, or removing
+ only one of two primary controllers, have no effect on the flow
+ table.
+ </p>