ed to be absolute and safe). In addition, logs should be stored in distant and safe environments. SDN CONTROLLER The controller maintains a outlook of the whole network, implements policy decisions, controls all the SDN devices that involve the network infrastructure, and provides a northbound API for applications. When have said that the controller implements policy decisions concerning routing, forwarding, redirecting, load balancing, and the similar to, these statements referred to both the controller and the applications that create use of that controller. Controllers frequently come with their individual set of common application modules, such as a learning switch, a router, a basic firewall, and a easy load balancer. These are really SDN applications, but they are over and over again bundled with the controller. The control plane in SDN and OpenFlow in particular is logically centralized and net apps are on paper as if the network is solitary organization. With a Reactive control representation, the OpenFlow switches have to consult an openflow controller every time a result must be made, such as what time a new packet flow reaches an OpenFlow switch. In the case of flow based control granularity, Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 SDN Controller there will be a little presentation delay as the first packet of each original flow is forwarded to the controller for result, after which future interchange within that flow will be forwarded at line rate inside the switching hardware. While the first packet delay is insignificant in many cases, it may be a concern if the middle OpenFlow controller is geographically remote or if the majority flows are short-lived. An alternative proactive approach is also probable in OpenFlow to push policy rules out from the controller to the switches. The Role of Controller in SDN Approach Multiple controllers may be used to decrease the latency or add to the scalability and fault tolerance of the OpenFlow (SDN) deployment. Open