Learn about the Network Simulation.

1. Unit -5 Network
Simulation

2. Nowadays, the advancement in wireless technology has been
increasing rapidly. In computer networks, the unproven protocols
cannot be initiated on a large scale because of the indecision of its
successful result. So, the latest protocols are tested through analytical
modeling otherwise simulation tools. If the latest protocols show
good results after the simulation, then the protocols will be executed
in the real world. Network simulation is the common and most useful
method, used to calculate various network topologies exclusive of
real-world implementation.

3. What is Network Simulation?
Definition: Network simulation is one kind of method in the research of a computer
network where a software program forms the performance of a network by analyzing the
relations between the various network entities such as links, Nswitched, routers, nodes,
access points. The network performance, different applications, services & supports can be
monitored in an analysis lab. Different features of the surroundings can also be changed in a
controlled way to evaluate how the network or protocols would perform beneath different
conditions.

4. Network Simulator
Software that is used to predict the performance of a computer network is known as a
network simulator. These are used when communication networks have turned into too
difficult for fixed analytical techniques to offer a precise understanding of system
performance. In a simulator, the computer network can be molded with the help of links,
devices and applications and the performance of a network can be reported. These are
available by using new networks and technologies which are used today like IOT, 5G, WLANs,
ad hoc networks of mobile, WSNs, LTE, ad hoc networks of vehicles, etc.
Network Emulation
This is one kind of method used to test the act of real applications over a virtual network.
This is dissimilar compare with network simulation wherever only mathematical form of
traffic, channels, protocols and network models are applied. The main function of this is to
assess performance, estimate the impact of change, and otherwise optimize decision-
making in technology.

5. Network Simulator 2 (NS2) : Features & Basic Architecture Of NS2
1. What is NS2
NS2 stands for Network Simulator Version 2. It is an open-source event-driven simulator designed specifically
for research in computer communication networks.
2. Features of NS2
1. It is a discrete event simulator for networking research.
2. It provides substantial support to simulate bunch of protocols like TCP, FTP, UDP, https and DSR.
3. It simulates wired and wireless network.
4. It is primarily Unix based.
5. Uses TCL as its scripting language.
6. Otcl: Object oriented support
7. Tclcl: C++ and otcl linkage
8. Discrete event scheduler
3. Basic Architecture
NS2 consists of two key languages: C++ and Object-oriented Tool Command Language (OTcl). While the C++
defines the internal mechanism (i.e., a backend) of the simulation objects, the OTcl sets up simulation by
assembling and configuring the objects as well as scheduling discrete events. The C++ and the OTcl are linked
together using TclCL

7. NS NETWORK SIMULATOR 3
NS Network Simulator 3 is a open source software, which mainly target system needs to
have a software development environment to build the libraries first, and then build the
user program. Ns Network Simulator 3 tracing system is built on the concepts of
independent tracing sources and tracing sinks, along with a uniform mechanism for
connecting sources to sinks. Another emphasis of Ns Network Simulator 3 is on the
reuse of real application and kernel code.
MERITS OF NS NETWORK SIMULATOR 3:
One of the fastest simulators around .
It’s a clean design.
It’s more flexible and scalable.
Most memory efficient simulation around.
No GUI to build topology.
Real-world integration.

8. Netki
Netki is open-source software that uses User-mode Linux. This simulator
is used whenever there is a need to form a networking environment
with small endeavors. It is a simulation tool based on the command line.
It is also used to create a total network over a single PC through
exploiting VN (virtual network) devices.

9. Marionnet is a virtual network laboratory: it allows users to define, configure and
run complex computer networks without any need for physical setup. Only a single,
possibly even non-networked Linux host machine is required to simulate a whole
Ethernet network complete with computers, routers, hubs, switches, cables, and
more Support is also provided for integrating the virtual network with the physical
host network.
Uses
The main goal of Marionnet is the teaching of computers networks in university
laboratories, although it could be a valuable tool also for high schools. Despite
being teaching-oriented Marionnet may be used to emulate networks for test or
development purposes. It is quite easy to set up, fast even with complicated
configurations and the possibility of reverting file system changes on virtual
machines makes it quite flexible.

16. OPNET Network simulator is a tool to simulate the behavior and performance of any type of network. The main
difference Opnet Network Simulator comparing to other simulators lies in its power and versatility. IT Guru provides pre-
built models of protocols and devices. It allows you to create and simulation different network topologies. The set of
protocols/devices is fixed – you cannot create new protocols nor modify the behavior of existing ones.
Advantages of Opnet Network Simulator:
Opnet Network Simulator is a open free software
Large number of project scenarios that are offered information on Opnet Network Simulator
Can be overlooked using Opnet Network Simulator.
Uses of opnet simulator:
Operational validation.
Application troubleshooting.
Network planning and design.
Validating hardware architecture.
Protocol modeling.
Traffic modeling of telecommunication networks.
Evaluating performance aspects of complex software systems.

17. QualNet
It is used for engineers, scholars to build virtual models for all kinds of data, voice & video networks. In fact, it is a testing,
planning and also a training tool used for signifying the network situation with accuracy.
. QualNet employs state of the art Parallel Discrete Event Simulation (PDES) algorithms designed to leverage multi-core and
parallel processors to dramatically increase the event processing rate and hence simulation execution speeds to run high-
fidelity simulations of large networks at faster than real-time speeds.
Features of QualNet
The major features of QualNet include the following:
QualNet can model a variety of heterogeneous networks (wired, wireless, under-water, satellite, etc.) with thousands of
nodes exchanging different types of traffic. These scenarios can run at faster than real-time speed, making it possible to
quickly perform “what-if” analysis of the network’s performance under different operating conditions.
QualNet supports a large number of high-fidelity models for network devices, protocols from all layers of the protocol stack,
applications, terrains, propagation models, and mobility models. The model library includes models for wireless
technologies (e.g., Wi-Fi and WiMax); cellular networks (e.g.,

18. GSM, UMTS, LTE, and 5G); military waveforms (e.g., Link-11, Link-16); satellite communications; underwater
communications; devices such as routers, switches, and access points; indoor, rural, and urban terrain; and many real-
world applications. Thus, real-world commercial and tactical networks operating in multiple domains can be modeled
and analyzed in QualNet at a high level of fidelity.
QualNet’s Human-in-the-Loop (HITL) interface supports dynamic interactions to modify the operations of a running
scenario. For example, users can activate/deactivate nodes and modify the traffic rate of certain applications via the HITL
interface.
The QualNet VR-Link interface allows QualNet to network with other constructive simulators, virtual reality applications,
and Computer-Generated Force (CGF) tools, such as OTB and OneSAF, using High Level Architecture (HLA) or Distributed
Interaction Simulation (DIS).
The QualNet GUI can be used to visualize different types of packet flows as the scenario is running to provide an
operational view of the network. Dynamic statistics can also be displayed while a scenario is running.
Orientation change extension FFC for Standard SIM