Networks Simulation PDF

# Networks Simulation ## Third Level ### Introduction To Network Simulations - Lecturer: MSC. Hussein M.Jebur ## What Is a Simulation? - The process of testing something through a model is known as simulation. - To perform simulation we can use software. In simulation software, data is input a...

# Networks Simulation ## Third Level ### Introduction To Network Simulations - Lecturer: MSC. Hussein M.Jebur ## What Is a Simulation? - The process of testing something through a model is known as simulation. - To perform simulation we can use software. In simulation software, data is input and with the help of data input and diagrams, we can get appropriate results. ## What’s Network Simulation - Simulation is one of the most widely used techniques in network design and management to predict the performance of a network system or network application before the network is physically built or the application is rolled out. - A network simulator is a piece of software or hardware that predicts the behavior of a network, without an actual network being present. - In simulators, the computer network is modeled with devices, links, applications etc. and the network performance is reported. - Simulators come with support for the most popular technologies and networks in use today such as 5G, IoT, WLAN, MANET, WSN etc. ## Emulator Versus Simulator | Emulator | Simulator | |---|---| | A hardware or software that enables one computer system (host system) to behave like some other system (guest system) | A computer program or a dedicated device that models some aspects of a real life situation and can be manipulated to observe the outcomes of different assumptions or actions without exposing the experimenter to any danger | | Helps to use a system as some other system | Helps to avoid risks | | Android studio emulator is an example for an emulator | Flight simulator, electronic device simulators are some examples for simulators | ## Why Simulation? - A simulation study can help in understanding how the system operates. - Used to: - Evaluate performance of existing network protocols. - Prototyping and evaluation of new protocols. - Large-scale simulations not possible in real experiments. ## Advantages of Network Simulator - Network simulators serve a variety of needs. - Compared to the cost and time involved in setting up an entire test bed containing multiple networked computers, routers and data links, network simulators are relatively fast and inexpensive. - Allow engineers to test scenarios that might be particularly difficult or expensive to emulate using real hardware. ## Advantages of Network Simulator (Cont.) - Simulating the effects of a sudden burst in traffic. - A DoS attack on a network service - Test new networking protocols or changes to existing protocols in a controlled and reproducible environment. - With the help of simulators one can design hierarchical networks using various types of nodes like computers, hubs, bridges, routers, optical cross-connects, multicast routers, mobile units etc. ## Types of Network Simulators - Various types of Wide Area Network (WAN) technologies like TCP, ATM, IP etc and Local Area Network (LAN) technologies like Ethernet, token rings etc. can all be simulated with a typical simulator. - The user can test, analyze various standard results apart from devising some novel protocol or strategy for routing etc. - A network simulator must enable a user to: - Represent a network topology. - Specifying the nodes on the network. - The links between those nodes. - The traffic between the nodes. ## Examples of Network Simulators - NS2 (Network Simulator Version 2) - NS3 (Network Simulator Version 3) - OPNET (Optimized Network Engineering Tool) - OMNET++ (Optical Micro - Networks Plus) - Netsim (Network Simulator) - J-Sim (JAVA SIM) - GNS3 - GlomoSim (Global Mobile Information System Simulator) - Cisco Packet tracer. ## NS2 (Network Simulator Version 2) - NS2 is a discrete event driven simulator, it is an open source simulator mostly used for academic research in the areas of Computer Networks, MANETs, WSNs. - Since the days of its first release it has energized the minds of students, researchers, network practitioners opened up many possibilities for doing simulation of different protocols before they are actually implemented in real time. ## NS3 (Network Simulator Version 3) - NS-3 is a discrete-event network simulator, targeted mainly for research and learning use. - NS-3 is a C++ library which provides a set of network simulation models implemented as C++ objects and wrapped through python. ## OPNET (Optimized Network Engineering Tool) - OPNET (Optimized Network Engineering Tool) simulator is a tool to simulate the behavior and performance of any type of network. The main variation with other simulators lies in its power and flexibility. - This simulator makes potential working with OSI model, from layer 7 to the alteration of the most essential physical parameters. - OPNET Technologies, was a software business that provided performance management for computer networks and applications. ## OMNET++ (Optical Micro - Networks Plus) - OMNET++ is an expendable, modular, component-based C++ simulation library and framework, mostly for building network simulators. - Components (modules) are programmed in C++, then assembled into larger components and models using a high-level language. ## Graphical Network Simulator-3 (Shortened to GNS3) - Is a network software emulator first released in 2008. It allows the combination of virtual and real devices, used to simulate complex networks. - GNS3 is used by many large companies including Exxon, Walmart, AT&T and NASA, and is also popular for preparation of network professional certification exams. ## Network Representation - Router - LAN Switch - LAN Hub - Server - Desktop Computer - Laptop - Firewall - IP Phone - Wireless Access Point - Wireless Router - WAN Media - LAN Media - Wireless Media ## What’s the Internet: “Nuts and Bolts” View - **Hosts:** PC, server, wireless laptop, smartphone, router - **Links:** wireless links, wired links - **Routers:** - **Protocols:** ## What’s The Internet: A Service View - **Comm Infrastructure**: - Web, VoIP, email, games, e-commerce, social nets, ... - **Comm Service**: - hooks that allow sending and receiving app programs to "connect" to Internet - provides service options, analogous to postal service ## What’s a Protocol? - **Protocol in a general sense**: Rules of interaction - **Network protocol**: protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt ## What’s a Protocol: A Human Protocol and a Computer Network Protocol: - **Hi** - **Got the time?** - **~2:00** - **Hi** - **Got the time?** - **~2:00** - **TCP connection to server** - **TCP connection response** - **Get http://www.cnn.com/business/kurose-ross** - **<file>** ## A Closer Look at Network Structure: - **Network edge**: - hosts: clients and servers - **Access networks**: - PHY links that connects hosts to edge routers - **Network core**: - interconnected routers - network of networks ## Access Networks and Physical Media - Q: How to connect end systems to edge router? - residential access nets - institutional access networks (school, company) - mobile access networks ## Introduction - A network system is a set of network elements, such as routers, switches, links, users, and applications working together to achieve some tasks. - The state of a network system is the set of relevant variables and parameters that describe the system at a certain time that comprise the scope of the study. - Instead of building a physical model of a network, we build a mathematical model representing the behavior and the logical and quantitative relations between network elements. ## Types of Simulation - Simulation models can be classified in many ways. The most common classifications are as follows: - Static and dynamic simulation models: A static model characterizes a system independently of time. A dynamic model represents a system that changes over time. - Stochastic and deterministic models: If a model represents a system that includes random elements, it is called a stochastic model. Otherwise it is deterministic. Queuing systems, the underlying systems in network models, contain random components, such as arrival time of packets in a queue, service time of packet queues, output of a switch port, etc. - Continuous model: A continuous model represents a system with state variables changing continuously over time. - Examples are differential equations that define the relationships for the extent of change of some state variables according to the change of time. - A discrete model characterizes a system where the state variables change instantaneously at discrete points in time. At these discrete points in time some event or events may occur, changing the state of the system. - For instance, the arrival of a packet at a router at a certain time is an event that changes the state of the port buffer in the router. ## Simulation Versus Emulation - The purpose of Emulation is to mimic the original network and reproduce every event that happens in every network element and application. - In Simulation, the goal is to generate statistical results that represent the behavior of certain network elements and their functions. ## Thank You For Listening - Any question