Network (Nunes, Mendonca, Nguyen, Obraczka, & Turletti, 2014) SDN Controller Middlebox (e.g. Firewall) Forwarding device with Forwarding device with decoupled control embedded control Software Control Traditional Network Software-Defined Network (with distributed control and middleboxes) (with decoupled control) History of SDN Although the origin of SDN dates back to decades ago, as early as 1980s, the implementation started just few years back, the first being the GSMP project developed by IPSILON in 1996, Tempest in 1998, and SS7 networks in 1993. The OpenFlow project is one of the most used implementation protocol, developed by the ONF in 2009. SDN is an emerging architecture that is dynamic, manageable, cost-effective, and adaptable, making it ideal for the high-bandwidth, dynamic nature of today's applications. (ONF SDN) The idea of centralized control plane and open protocol has traveled a long journey to finally evolve as SDN and Open flow. The few projects are worth mentioning that has nurtured the idea of centralized control plane and programmable networks. These projects have laid the foundation of SDN networks that are described below. Open Signaling: This project has been started as an attempt to improve the ATM, internet and mobile networks. The Project OPENSIG (Campbell, Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Introduction to SDN and NFV Katzela, Miki & Vicente, 1999) is focused on creating open, extensible and programmable networks. The concept they proposed was separation of control logic from hardware circuitry SO that better deployment of services can be done using open interfaces. The Proposed project emphasized on making the protocols open. Based on this, IETF developed General Switch Management Protocol GSMP (rfc 3292) (Doria 2002). Active Networking: The Active Networking concept comes up with the idea of programmable networks. They proposed two concepts - a programmable switch and capsules which is useful in sending control codes along with the