SDN Controller Load Balancing

The use of multiple controllers in SDN can be due to performance improvements, scalability, and reliability. That is, traffic can be processed much faster and a fault in one controller can be hidden by another one with multiple controller usage . 
To take advantage of multiple controllers, one can distribute the load on the controllers in such a smart way that SDN does not suffer from high traffic and consequently latency, low bandwidth, and even worse, crashes.