 to as southbound application programing interface (API). A common, open standard SDN protocol, and one of the most popular options for southbound APIs is OpenFlow. Northbound API The opposite of the southbound API is the northbound API, which is labelled as just API; connections from a business application to the controller are involved. Anybody with basic knowledge of programming can create an SDN application. The SDN application itself can be written to perform a very large set of potential activities; the most basic of which could be to tell a deployed device to forward a packet with a matching set of contents out a specific interface. However, the northbound API can be very complex, like providing a Quality of Service provisioned path from Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Analysis of Issues in SDN Security and Solutions one end of a network to another dynamically, then tearing it back down when the application was completed with its network interaction. The SDN controller is responsible for abstracting the network of SDN devices it controls and presenting an abstraction of these network resources to the SDN applications running above. The controller allows the SDN application to define flows on devices and to help the application respond to packets that are forwarded to the controller by the SDN devices. Since one controller can control a large number of network devices, these calculations are normally performed on a high-performance machine with an order-of-magnitude performance advantage over the CPU and memory capacity than is typically afforded to the network devices themselves. For example, a controller might be implemented on an eight-core, 2-GHz CPU versus the single-core, 1-GHz CPU that is more typical on a switch. SDN applications are built on top of the controller. These applications should not be confused with the application layer defined in the seven-layer OSI model of computer networking. SDN application is part of network layers two and thr