NFV is initiated from the Telecom Service Provider (TSP) SO that they can achieve high return of investment i.e. ROI along with a flexible infrastructure where deployment and integration is faster and easier. This chapter consists of two sections. The first section will cover the SDN definitions, evolution and architecture of SDN along with challenges and future trends. The second section will cover the NFV definitions, evolutions and architecture of NFV along with challenges and future trends. INTRODUCTION TO SOFTWARE DEFINED NETWORK (SDN) (Haleplidis, Pentikousis, Salim, Meyer, koufopavlou(2015)) in RFC 7426 describes Software Defined Networks as: Software-Defined Networking (SDN) refers to a new approach for network programmability, that is, the capacity to initialize, control, change, and manage network behavior dynamically via open interfaces. SDN emphasizes the role of software in running networks through the introduction of an abstraction for the data forwarding plane and, by doing so, separates it from the control plane. By following the above definition we can deduce the following salient features of a SDN network: Programmable Network Centralized Management Dynamically Configurable Networks Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Introduction to SDN and NFV Open Protocols and Interfaces Easily Monitored and Fault Tolerant Network Need of SDN According to Gens, F. (2012), as we follow recent trends in ICT due to the emergence of Cloud Computing, Mobile Computing and IOT the network traffic has growing exponentially. According to Cisco VNI (2016), "Annual global IP traffic will reach 3.3 ZB (ZB; 1000 Exabytes [EB]) by 2021 and Global IP traffic will increase nearly threefold over the next 5 years, and will have increased 127-fold from 2005 to 2021" The evolution of social media, ubiquitous computing, IOT and smartphones has not only increased the bandwidth requirements but also the complexity of the networks. This leads to massive increase in east west traffi