SDN network supports centralized network management by splitting control plane and data plane of forwarding devices and places the network intelligence in a software entity called controller. The controller can be placed in selective places of network to effectively monitor and control network activities. Large scale network needs multiple controller to manage control activities of network. In order to identify the optimum number of controllers and its effective locations in the network, a new algorithm is proposed using cut-vertex concept from graph theory. The proposed algorithm is simulated using Mininet SDN emulator. To study the performance of the proposed algorithm, multiple scenarios were used in the simulation and performance was analysed using parameters viz., flow installation time, average latency of network, throughput.