A Brief Introduction To OpenFlow, November 14, 2011 OpenFlow is
a specification now managed by the Open Networking Foundation,
which defines the functions and protocols used to centrally
manage switches via a centralized controller. While OpenFlow has
a centralized controller, that doesn't mean that each new flow
has to result in a controller lookup. If a new flow matches an
existing rule, it will be processed according to that rule's
actions. Rules can be pre-populated, reducing the number of
lookups that occur. Intelligent policy development should mean a
reduced number of controller lookups. In addition, rules have a
time to live associated, so if the switch is disconnected from
the controller for some reason, it can still process existing
and new flows. Only those flows that result in a controller
lookup would fail. Controller technology is not new either.
Enterprises have been using controller-based wireless and
network access control for years successfully.