ation with the help of NFV we can achieve high gain in OSS and BSS. Network Functions Virtualization Industry Specification Group (NFV ISG) Network Functions Virtualization Industry Specification Group (NFVISG) which is a part of the European Telecommunications Standards Institute (ETSI) published a white paper on NFV in October 2012, at a conference in Darmstadt, Germany on SDN and OpenFlow. NFV ISG was formed of representatives from the telecommunication industry across Europe and beyond. Since the launch in 2012, the NFV ISG has grown to 235 companies. The main focus of NFV ISG is to provide interoperability for NFV solutions coming from different vendors in an open ecosystem. The key requirement for the interoperability is to provide standard interface SO that they different standard can be amalgamated. Second focus is to provide a hierarchy of orchestrators which in many cases will be operated by independent organization and in multi-tenant mode. The third focus of this is to find interaction of NFV with existing legacy OSS/BSS components. The fourth thing is to standardize the possible service models such as NFVIaaS, NFVPaaS and NFVSaaS. HISTORY OF NFV The concept of logical network started way before formal NFV was proposed in 2012. The categorizations in which the history of NFV can be divided are: Virtual LAN Virtual Private Network Active and Programmable Networks Overlay Networks Virtual LAN VLAN created a logical LAN SO that all the devices which belong to the same VLAN lies in the same broadcast domain without considering their physical locations. The Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Introduction to SDN and NFV specialized switches are needed for VLAN to implement. All VLAN frames carry a VLAN ID SO that a frame should reach all the devices belonging to the same VLAN. The configuration and management of VLAN are easier since a virtual network. Virtual LAN are also use to divide the broadcast domain of a switch in different VLANs. Virtual Private Ne