# Server Operation and Virtualization to Save Energy and Cost in Future Sustainable Computing
## 1 Introduction  
Given the diversity of mobile devices nowadays, the number of entities has increased explosively, resulting in the sharp increase of data traffic. To cope with such an issue, telecommunication service providers have tried to keep up with the demands for network capacity increase with network hardware equipment. To accommodate various data and signaling required by different terminals, however, it is inefficient to have the current network equipment only. This is because the current network structure that depends on a specific manufacturer can neither provide the various services represented by 5G (5 th-Generation mobile communications) and IoT (Internet of Things) nor cope with the traffic changes quickly through the construction of flexible maintenance and repair environment. To deal with such problems, the need for NFV (Network Function Virtualization) is raised. NFV technology is one of the virtualization technologies that realized the Network Function with compatible server, switch, and storage beyond the dedicated network equipment of a specific manufacturer. By implementing software, which can be operated on any infra resource on commercial hardware that is easy to install and change, the telecommunication service provider realizes operation efficiency and quick services for a cost-effective network. Therefore, this study proposes server operation and virtualization techniques for energy and cost reduction for NFV for future sustainable computing. The purpose of this study is to design and study the virtualization network focusing on NFV technology, which is in the spotlight in telecommunication among virtualization technologies recently used for cost reduction. The study is based on the 3 rd quarter of 2016. Meanwhile, a normal system is operated with one OS per system. In this case, the use rate of a normal system is less than 2\(\sim\)30%. The concept of virtualization seemed to supplement the disadvantage of low use rate compared with the available resources of the equipment. Virtualization is a technology that separates resources by abstracting physical resources logically using hypervisor technology. If virtualization technology is applied, it can use the system only up to 80% by operating multiple operating systems in one system. Virtualization technologies can be classified into application virtualization, desktop virtualization, server virtualization, storage virtualization, and network virtualization. The biggest advantage of virtualization is the reduction of cost and efficiency of operation. Since the amount of necessary hardware is reduced while operating the system efficiently, the purchase cost, power consumption, and phase area were reduced, thus resulting in the reduction of operating cost. In addition, it can realize the integrated management of dispersed resources. As a result, the demand for virtualization is increasing. The pattern and quantity of network traffic increased alongside the diversity of demand and type of personal devices. Since mutual connection is required, the cloud service is increasing sharply. To cope with such demand, telecommunication service providers are required to provide different systems. Since there is a possibility of expanding the network capacity to unimaginable levels, many enterprises consider virtualization as a solution. With its merits such as effective operation and cost reduction, many enterprises have conducted sustainable reviews to introduce virtualization. In many regions, telecommunication service providers encounter a serious task. To cope with rapidly increasing 4G LTE (4 th Generation Mobile Communications Long Term Evolution) traffic speed from mobile devices and IoT sensors, they have to expand core network elements including the Evolved Packet Core (EPC, 3 GPP Mobile Competence Centre, Sophia Antipolis Cedex, France) and control cost. All converged sounds and data traffic of mobile devices with 4G LTE function are transferred to the fixed core of a network of telecommunication service providers through EPC.