Survey of Promising Technologies for 5G Networks <s> Network Function Virtualization (NFV). <s> Software defined networking (SDN) and network function virtualisation (NFV) have become hot topics in recent years. On one hand, SDN decouples the control plane from the data plane allowing the rapid innovation and the introduction of new services in an easy way. On the other hand, currently proprietary appliances such as load balancers and firewalls are implemented in hardware, NFV aims to change these network functions to an open software environment using virtualisation and cloud technologies. This means a reduction of spends in the provisioning and management of telecom services. SDN and NFV are two different concepts but these can coexist and help each other. In this study, the authors present a survey of SDN and NFV focusing in virtualisation projects and the use cases where a synergy between these technologies is possible. This study includes the basic concepts of network virtualisation, NFV and SDN, current research and the relation between both technologies. <s> BIB001 </s> Survey of Promising Technologies for 5G Networks <s> Network Function Virtualization (NFV). <s> Communication networks are changing. They are becoming more and more “software- based.” Two trends reflect this: the use of software defined networking and the use of virtualization to exploit common off-the-shelf hardware to provide a wide array of network-resident functions. To truly achieve the vision shared by many service providers of a high-performance software-based network that is flexible, lowercost, and agile, a fast and carefully designed network function virtualization platform along with a comprehensive SDN control plane is needed. The shift toward software-based network services broadens the type of networking capabilities offered in provider networks and cloud platforms by allowing network services to be dynamically deployed across shared hosts. Combining this with an SDN control plane that recognizes the power of a dynamically changing network infrastructure allows network functions to be placed when they are needed and where they are most appropriate in the network. Our system, SDNFV harmoniously combines the two fast moving technological directions of SDN and virtualization to further the goal of achieving a true software-based network. <s> BIB002
An important observation of SDN is NFV BIB001 . SDN and NFV are mutually beneficial, but they are not fully dependent on each other. In fact, network functions can be employed and virtualized without using an SDN and vice versa. As it is complementary to SDN, NFV can effectively decouple network functionalities and implement them in software. Thus, it can decouple network functions, for instance, routing decisions, from the underlying hardware devices such as routers and switches, and centralize them at remote network servers or in the cloud through an open interface such as OpenFlow. Hence, the overall network architecture can be highly flexible for fast and adaptive reconfiguration. The combined functionalities of SDN and NFV BIB002 make SDNs more advantageous than traditional hardware-based networks. The main advantages can be listed as follows: cost minimization, reduced power consumption through equipment consolidation, reduced processing time by minimizing the typical network operator cycle of innovation, centralized network provisioning by decoupling the data plane from network control plane, extension of capabilities, hardware savings, cloud abstraction, guaranteed content delivery, physical versus virtual networking management, and so on. The advantages of SDN are well explained in  . Figure 1 shows a comparison between conventional hardware-based networks and SDN. Furthermore, the differences between SDN and conventional hardware-based networks are summarized in Table 1 .