the performance of virtualization in real time environment, placement of virtual appliances, instantiation and migration of Virtual appliances. Network Performance of Virtualized NF: Although virtualization seems promising to reducing the Capex and Opex and provide flexibility to the network but performance will be a point of concern due to unpredictability in real time load. Some studies show that running the virtual appliances on a multiprocessor environment leads to poor throughput of TCP/UPD packets. Placement of Virtual Appliances: Placement of middle boxes is another aspect to be looked at. Placement of virtual appliances cannot be at the same place where original middle boxes are placed. Moving middle boxes to the data center will increase unnecessary traffic which causes delay. Many appliances in the network are placed according to the topology SO as to minimize delay. Since the VA are usually run as VM, putting these VMs on the edge network will be more beneficial. Instantiation and Migration of Virtual Appliances: VNF are meant to increase the network flexibility by providing the network functions as per the dynamic requirements. These dynamic instances are the VM that need to be instantiated and also migrated to provide flexibility. The process using native VM is not efficient, SO different solution is required to be suitable for NFV. Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Introduction to SDN and NFV Energy Efficiency: In the telecom industry the energy bills are one of the most significant portions of the expenditure. NFV promises to reduce the energy cost by virtualization. The number of devices can be increased or decreased as per the need but this makes the telecom services dependent on the cloud computing. So the energy efficiency of NFV will be become dependent on the cloud computing. Security, Privacy, and Trust: Implementing the Virtualized NF over the public cloud will incorporate the security issues that are already present in the cloud computing