ol from forwarding lets administrators dynamically adjust network-wide traffic flow to meet changing needs. Centrally managed Open standards-based and vendor-neutral This means SDN control software sits at top of physical infrastructure layer composed of networking devices, with which it communicates via a control plane interface such as Open Flow (Kanaumi Y., Saito S., Kawai E., Ishii S., Kobayashi K., Shimojo S. (2013)). The idea is to turn networks into flexible, programmable platforms to optimize resource utilization, making them more cost effective and scalable. By providing APIs for business applications and services, SDN also promises to recast information technology by integrating cloud-based services and capabilities, and high-speed networking, into the computing fabric. SDN OPERATION The SDN devices contain forwarding functionality for deciding what to do with each incoming packet. The devices also contain the data that drives those forwarding decisions. The data itself is actually represented by the flows defined by the controller, as depicted in the upper-left portion of each device. A flow describes a set of packets transferred from one network endpoint (or set of endpoints) to another endpoint (or set of endpoints). These endpoints may be defined as IP address-TCP/UDP port pairs, VLAN endpoints, layer three tunnel endpoints, and input ports, among other things. One set of rules describes the forwarding actions that the device should take for all packets belonging to that flow. It can be understood from Figure 2 that flow is unidirectional, packets flowing between the same two endpoints in the opposite direction could each constitute a separate flow. Flows are represented on a device as a flow entry. A flow table resides on the network device and consists of a series of flow entries and the actions to perform packet matching, when the SDN device receives a packet, it consults its flow tables in search of a match. These flow tables had been Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University