# Server Operation and Virtualization to Save Energy and Cost in Future Sustainable Computing
## 3 Server Operation and Virtualization to Save Energy and Cost
### OpenFlow Based Virtual EPC Test Bed at Lab  
Figure 7 show the overall structure of the OpenFlow-based virtual EPC test bed. First, each EPC component realized with software is operated in 5 virtual machines that form multiple VLAN (gray box) to facilitate communication between components. In addition, it enables making direct communication between components through a separate Management Network (red dot line), and it is set to send and receive the message between OpenFlow data/control areas through the Management Network. The virtual machines in the test bed are created on general x86-based servers. 160 GB hard disk and 2 processors are allocated. 16 GB memory is allocated to the virtual machine on the data area switch (SGW-U and PGW-U), with 8 GB memory allocated to the other virtual machine.  
The constructed virtual EPC function is connected to an actual commercial LTE station. IP.Access's LTE 245F small cell is used as LTE station [26; 27; 38; 39], and Nexus 5 is used as terminal. The Band 7 supported from the Nexus 5 terminal in the test bed is allocated and used. The scope of use is restricted inside the RF shield room that blocks wireless signal considering the collusion with commercial LTE frequency bandwidth that is under service in the country.  
Following the increase in system size, and due to the emergence of various attack routines, the volume of data that needs to be processed has increased astronomically. As such, we have constructed a system that can process data by combining several PCs using the concept of computer clustering technique and virtualization technology (VMware). The improvement in the performance level of the system and the flexibility of the test bed have been tested by using an exclusively designed algorithm whose results were clearly preferable.  
As mentioned earlier, it is quite difficult to construct an analytical model for the complex system. This is because the necessary experiments are often conducted within small-scale internal intranet networks or reduced test beds. To assist the learners in the security curricula, we have devised a clustering system-based test environment by using virtualization technology and open-source Linux.  
Network Function Virtualization (NFV) is to virtualize the telecommunication device and to install it in the compatible service as a form of software for telecommunication service, unlike conventional way of equipping a specific hardware.  
The greatest merit of vEPC is it can be installed within a few hours while existing LTE exchangers requires several months for installation. In addition, it can extend capacity simply by allotting additional servers without construction of new equipment. In doing so, the new communication service time is significantly reduced. Furthermore, it can cope with an unexpected increase of traffic situation flexibly so that it can provide more stable service. Also, since vEPC is commercialized for IoT service initially, it can cope with the data traffic increase due to an extensive introduction of IoT services. This paper discusses vEPC in terms of server operation and virtualization to save energy and cost, and it manufactures an Android application to provide convenience for users (server administrators).  
Figure 7: OpenFlow Based Virtual EPC Test Bed Layout.