Simulation Analysis of Characteristics and Application of Software-Defined Networks Ivan Grgurevi, Zvonko Kavran, Anthony Pušelji (student) Faculty of Transport and Traffic Sciences, University of Zagreb Department of Information and Communication Traffic Zagreb, Croatia ivan.grgurevic@fpz.hr Abstract - Software-defined network (SDN) is an approach to computer networking that allows network administrators to manage network services through abstraction of higher-level functionality. This research includes comparison of multiple scenarios of the software-defined network, which are based on different types of coverage and local area networks (LAN), i.e. a traditional LAN. Differences are evident in the scenario of network performance and can be perceived as advantages and disadvantages of SDN in relation to the traditional network. The parameters used in the analysis are data rate, packet delay (i.e. latency), packet loss, throughput, the cost of network performance and others. The application and the simulation demonstration of a software-defined network is shown in the graphical network simulator GNS and emulator Mininet. This research has analysed the advantages and disadvantages of a software-defined network over a conventional network, taking into account various parameters and stakeholders. Keywords - Software-defined network/networking, simulation analysis, controller, Application programming interface (API) I. INTRODUCTION Nowadays, we are witnessing a very high degree of application of virtualization technologies with the growing customer demand for a fast establishment and delivery of services and placement services within the Cloud Computing concept. In addition, users require flexible and automated network environment that is adaptable to current applicative requirements. Such new challenges require responses by the application of a different approach in relation to the classical network infrastructure management. Cloud computing allows users to store data and install software on the servers that are connected through the Internet. With the help of a web browser and special customers, these services are flexible and the users pay only for what they use. Software-defined network (SDN) is a network architecture in which the networks control is separated from the packet forwarding and it contains the possibility of direct programming. Such migration of control, which is sometimes strongly related to an individual network device, in the external computing devices allows basic infrastructure separation of applications and network services, which are therefore able to treat the network as a logical or virtual entity. SDN enables dynamic adjustment of the network environment to the current application requirements or the user’s needs, and simplifies management and increases the scalability of the network, which is particularly manifested through a simple implementation of additional network services and components. An additional benefit of SDN is the possibility of using the network components from different manufacturers, basically without having to know how to operate the devices since the complete network environment is managed from a single point, or through the SDN controller. The SDN network architecture consists of a controller SDN, OpenFlow network devices and a communication channel that connects them. Today, the largest application of SDN is present in data centers which are also known as software-defined data centers (SDDC). Such data centers contain all the elements of the infrastructure needed for networking, storage, processing (Central processing unit - CPU), the realization of security and virtualization, and are being delivered as a service. Development, provisioning, configuring, and other operations of the whole infrastructure are separated from the hardware and executed by the software. The aim of this research was to conduct an analysis of the characteristics and the application of software-defined networks. The analysis is based on a comparison of conventional networks and software-defined networks with the display of significant differences. The research includes a simulation of different network topologies using the graphical network simulator GNS3 on Linux. For the purposes of the simulation, it was necessary to specify the differences between network architecture of traditional networks and software- defined networks, and to conduct the process of designing software-defined network via a graphical network simulator GNS3 and emulator Mininet. The research is in fact an analysis of different scenarios and parameters (data rate, packet delay, packet loss, throughput, the cost of network performance, etc.). II. BACKGROUND AND RELATED WORK Numerous available articles and research are dealing with the analysis of the characteristics and architecture of software- defined networks / networking, and the analysis is mainly based on the impact due to changes in certain performance of the network and the application of SDN controller [1], [2], [3]. Within the development of the Internet of Things (IoT) concept, many authors reveal the application of software- defined networks / networking and access in the IoT environment, and thus achieve the differentiation level of service due to the different needs of IoT in different (heterogeneous) scenarios, especially related to the wireless networks [4], [5], [6]. The development of software for the simulation of the operation of information and communications