How to model and simulate a computer network
OPNET stands for Optimized Network Engineering Tool. It is used to simulate computer networks. The design and configuration of
new communication networks is becoming more and more complicated due to the increasing offer of new products to renew and
increase networks. Hence for these reasons, it is necessary to use such a simulation tool with the characteristics of opnet. By
simulating changes such as technology migration, traffic growth and failures, opnet can help fix existing performance problems
before they occur. OPNET provides a virtual network environment where it is possible to analyze and optimize network
applications, configurations and traffic flow in nearly limitless range of “what if ” scenarios.
Simulation is the process of mimicking or imitating a real world process over time.
OPNET is a network simulator which contains a comprehensive development environment supporting the modeling and
performance evaluation of communication networks and distributed systems. OPNET has advantages over other major network
simulation software packages because of its ability to stay in touch with new communication network technologies, quality of
documentation, simulation platforms and whether the software meets all the needs for use in a data communications.
OPNET uses models that are specified in terms of objects, each with configurable sets of attributes. Models are hierarchical to
naturally parallel the structure of actual communication networks. The hierarchical approach allows for deep nesting of
subnetworks and nodes and large networks can be efficiently modeled.
OPNET has a wide variety of possibilities. Enables the possibility to simulate entire heterogeneous networks with various
protocols Development work was started in 1986 by MIL3 Inc. Originally, it was developed for the needs of millitary, but it has
grown to be a world leading commercial network simulation tool. OPNET is quite expensive for commercial usage but there are
also free licenses for educational purposes.
OPNET is a high level event based network level simulation tool. Originally built for the simulation of fixed networks. OPNET
contains a huge library of accurate models of commercially available fixed network hardware and protocols. Nowadays, the
possibilities for wireless network simulations are also very wide. Accurate radio transmission pipeline stage for the modeling of
the physical layer (radio interface).
The simulator has a lot of potentiality, but there exists typically a lack of the recent wireless systems. OPNET can be used as a
research tool or as a network design/analysis tool. With OPNET’s simulation tool it is possible to combine several low level
attributes and make series of simulations. The basic simulations with OPNET are done as a function of simulation timeto ensure
accurate network behavior. The level of event accuracy can be extended to be as detailed as needed. Simulation results as a
function of time are typically as such not suitable as scientific results, since statistical accuracy is needed. A certain situation can
be first verified with a simple simulation. OPNET is an event based network simulation tool. Using only simulations is quite
straightforward. Hierarchical structure, modeling is divided to three main domains: Network domain, Node domain and process
domain.
The Network DomainNetwork domain specifies the overall scope of the system to be simulated.
It is a high-level description of the objects contained in the system. Network model specifies the objects in the system as well as
their physical locations, interconnections and configurations.The Network Domain (sub-networks): An example of a sub-network
(WLAN) Fixed links sub-netnetwork nodes.The Network Domain (Mobility): Mobility trajectory whereby a node follows a
predetermined trajectory during simulation Mobility vector where a node moves according to a mobility vector defined with node
attributes, which can be modified during simulation and it also allows manipulation of node’s coordinates.
Node DomainThe node model specifies the internal structure of a network node. Typical nodes include workstations, packet
switches, satellite terminals, remote sensors. Nodes can be fixed, mobile or satellite type. A node can also be a special kind of
node representing e.g., an entire Ethernet or Token Ring network and its aggregate traffic as one entity
Process DomainƒA process is an instance of a process model. ƒProcesses can dynamically create child processes. With OPNET’s
simulation tool it is possible to combine several low level attributes and make series of simulation iterations.
The basic simulations with OPNET are done as a function of simulation time to ensure accurate network behavior. The level of
event accuracy can be extended to be as detailed as needed. On the Physical Layer Modeling, the physical layer is modeled with
pipeline stages, which are used to calculate step by step the total effect of the physical transmission medium including all the
interference caused by other users. OPNET is event based network simulation tool which is powerful but also demanding. Using
only simulations is quite straightforward • Modeling is done mainly in three levels Network Domain (top level), Upper levels hide
the complex structure of the lower level components, which can be totally invisible to the end user, Node Domain and Process
Domain. Different layers and functionalities can practically be modeled as accurately as needed with external model access.
WHAT ARE THE FEATURES OF OPNET?
OPNET simulator has the following features.
*Network Editor that specifies network topology and configure nodes and links.
*Node Editor with which you can create models of nodes by specifying internal structure and capabilities and create your own
devices
*Process Editor that develops models of decision-making processes representing protocols, algorithms, resource management,
operating systems, etc.
*Link Model Editor
Three domains: Network, node, and process ƒNode model specifies object in network while domain ƒProcess model specifies object
in node domain.
Network Domain: Network Objects
ƒNetwork models consist of nodes, links and subnets ƒNodes represent network devices and groups of devices, servers,
workstations, routers, LAN nodes, IP clouds, etc. ƒLinks represent point-to-point and bus links ƒIcons assist the user in quickly
locating the correct nodes and links ƒVendor models are distinguished by a specific color and logo for each company Generic
DevicesVendor Devices.
*Path Editor
*Packet Format Editor
*Scenario: is a single instance of the network. It represents a unique configuration of the network.
*An object palette is a graphical dialog box that displays a group of nodes and link models. Object palettes can be customized to
contain only the nodes and links that we need.ƒ
*Annotation Palette: ƒOpen by selecting Topology / Open Annotation Palette ƒAdd rectangles, circles, lines and text to models to
enhance their appearance ƒThis method is an effective way to graphically illustrate and document the changes made to a model ƒ
Does not affect analysis ƒAnnotations can be temporarily hidden
*Event-Driven Simulation
ƒEvents are specific activities that occur at a certain time. ƒOPNET simulations are event-driven . Simulation time advances when an
event occurs. ƒA different method might be to sample at regular intervals. ƒSimulation time advances only when an event with a
later time is processed from the event list ƒNo simulation time occurs during the execution of a process ƒNo time elapses during
transitions between states ƒA process model must always have an unforced (red) state so timecan advance zAvoid endless looping
between forced (green) states.
A radio link, established during a simulation, can be created between any radio transmitter-receiver channel pair. Satellite and
mobile nodes must use radio links. Fixed nodes may use radio links. A radio link is not drawn but is established if nodes contain
radio transceiver. Using OPNET it is possible to generate scenarios and create new models. It can simulate, design and test the
entire network including hardware devices
Such as server, switches, protocols, routers and individual applications, etc.
Network planner, IT manager and network administrator are now able to solve
All the difficult problem more effectively and validate changes before starting a
Real implementation. If we start implementing a network before simulate, it
Costs a lot to change any part of the network and waste time. All data are
Available to access network performance.
OPNET Modeler – Opnet modeler is the main tool for capacity planning and design.
WHAT IS OPNET USED FOR?
OPNET inherently has three main uses: modeling, simulating, and analysis. For modeling, it provides intuitive graphical
environment to create all kinds of models of protocols. For simulating, it uses 3 different advanced simulations technologies and
can be used to address a wide range of studies. For analysis, the simulation results and data can be analyzed and displayed very
easily through graphs or charts
For network simulation, more specifically, it means that the computer assisted simulation technologies are being applied in the
simulation of networking algorithms or systems by using software engineering. The application field is narrower than general
simulation and it is natural that more specific requirements will be placed on network simulations. For example, the network
simulations may put more emphasis on the performance or validity of a distributed protocol or algorithm rather than the visual
or real-time visibility features of the simulations. Moreover, since network technologies is keeping developing very fast and so
many different organizations participate in the whole process and they have different technologies or products running on
different software on the Internet. That is why the network simulations always require open platforms which should be scalable
enough to include different efforts and different packages in the simulations of the whole network. Internet has also a
characteristic that it is structured with a uniformed network stack (TCP/IP) that all the different layers technologies can be
implemented differently but with a uniformed interface with their neighbored layers. Thus the network simulation tools have to
be able to incorporate this feature and allow different future new packages to be included and run transparently without harming
existing components or packages. Thus the negative impact of some packages will have no or little impact to the other modules
or packages.
Network simulators are used by people from different areas such as academic researchers, industrial developers, and Quality
Assurance (QA) to design, simulate, verify, and analyze the performance of different networks protocols. They can also be used to
evaluate the effect of the different parameters on the protocols being studied. Generally a network simulator will comprise of a
wide range of networking technologies and protocols and help users to build complex networks from basic building blocks like
clusters of nodes and links. With their help, one can design different network topologies using various types of nodes such as
end-hosts, hubs, network bridges, routers, optical link-layer devices, and mobile units. Generally speaking, network simulators try
to model the real world networks. The principal idea is that if a system can be modeled, then features of the model can be
changed and the corresponding results can be analyzed. As the process of model modification is relatively cheap than the
complete real implementation, a wide variety of scenarios can be analyzed at low cost (relative to making changes to a real
network). However, network simulators are not perfect.
They can not perfectly model all the details of the networks. However, if well modeled, they will be close enough so as to give a
meaningful insight into the network under test, and how changes will affect its operation.
In the research area of computer and communications networks, simulation is a useful technique since the behavior of a network
can be modeled by calculating the interaction between the different network components. They can also be modeled by actually
or virtually capturing and playing back experimental observations from a real production networks. All kinds of environmental
attributes can also be modified in a controlled manner to assess how the network can behave under different parameters
combinations or different configuration conditions. Another characteristic of network simulation that worth noticing is that the
simulation program can be used together with different applications and services in order to observe end-to-end or other point-
to-point performance in the networks. In the network research area, it is very costly to deploy a complete test bed containing
multiple networked computers, routers and data links to validate and verify a certain network protocol or a specific network
algorithm. The network simulators in these circumstances save a lot of money and time in accomplishing this task. Network
simulators are also particularly useful in allowing the network designers to test new networking protocols or to change the
existing protocols in a controlled and reproducible manner.
Simulation is a very important modern technology. It can be applied to different science, engineering, or other application fields
for different purposes. Computer assisted simulation can model hypothetical and real-life objects or activities on a computer so
that it can be studied to see how the system function. Different variables can be used to predict the behavior of the system.
Computer simulation can be used to assist the modeling and analysis in many natural systems. Typical application areas include
physics, chemistry, biology, and human-involved systems in economics, finance or even social science. Other important
applications are in the engineering such as civil engineering, structural engineering, mechanical engineering, and computer
engineering. Application of simulation technology into networking area such as network traffic simulation, however, is relatively
new. For network simulation, more specifically, it means that the computer assisted simulation technologies are being applied in
the simulation of networking algorithms or systems by using software engineering. The application field is narrower than general
simulation and it is natural that more specific requirements will be placed on network simulations. For example, the network
simulations may put more emphasis on the performance or validity of a distributed protocol or algorithm rather than the visual
or real-time visibility features of the simulations. Moreover, since network technologies is keeping developing very fast and so
many different organizations participate in the whole process and they have different technologies or products running on
different software on the Internet. That is why the network simulations always require open platforms which should be scalable
enough to include different efforts and different packages in the simulations of the whole network. Thus the negative impact of
some packages will have no or little impact to the other modules or packages. However, network simulators are not perfect.
In the research area of computer and communications networks, simulation is a useful technique since the behavior of a network
can be modeled by calculating the interaction between the different network components (they can be end-host or network
entities such as routers, physical links or packets). After we get the observation data from simulation experiments, the behavior
of the network and protocols supported can then be observed and analyzed in a series of offline test experiments.
Another characteristic of network simulation that is worth noticing is that the simulation can be used together with different
applications and services in order to observe end-to-end or other point-to-point performance in the networks. Users can easily
visualize the workings of their simulated environment. Some of them may be text-based and can provide a less visual or intuitive
interface, but may allow more advanced forms of customization. Others may
OPNET is the registered commercial trademark and the name of product presented by OPNET Technologies incorporation. It
became one of the most famous and popular commercial network simulators by the end of 2008. Because of has been used for a
long time in the industry, it became mature and has occupied a big market share.
It can be flexibly used to study communication networks, devices, protocols, and applications. Because of the fact of being a
commercial software provider, OPNET offers relatively much powerful visual or graphical support for the users.
OPNET is based on a mechanism called discrete event system which means that the system behavior can simulate by modeling
the events in the system in the order of the scenarios the user has set up. Hierarchical structure is used to organize the networks.
As other network simulators, OPNET also provides for users to define the packet format of the protocol. As of all, OPNET is a
popular simulator used in industry for network research and development. Because of the consistent endeavor and operation of
OPNET Inc., OPNET is becoming mature and its product maintain a high acknowledge in the industry. Moreover, OPNET always
keeps an eye on the most recent users's requirements and keeps improving their product which make it very competitive
compared with other commercial network simulators in the near expectable future.
What is the history of OPNET Technologies, Inc?
OPNET Technologies, Inc. is a Delaware corporation that was incorporated in November 1988. The Company is a provider of
software products and related services for managing applications and networks. Its software products address application
performance management, network planning, engineering and operations, and network research and development. The
Company's customers include corporate enterprises, government and defense agencies, network service providers, and network
equipment manufacturers. The Company's software products and related services are designed to help its customers make better
use of resources, reduce operational problems, and improve competitiveness. It focuses on analytics and producing actionable
results. It is engaged in the development and sale of computer software programs and related services. The Company's
operations are principally in the United States, and it has subsidiaries in Belgium, France, Germany, the United Kingdom and
Singapore. The Company markets software products and related services in North America primarily through a direct sales force
and, to a lesser extent, several resellers and original equipment manufacturers. Internationally, the Company conducts research
and development through a wholly-controlled subsidiary in Ghent, Belgium and markets software products and related services
through wholly-owned subsidiaries in Paris, France; Mainz, Germany; Slough, United Kingdom; and Singapore; a sales office in
Beijing, China; third-party distributors; and value-added resellers. Its software products use a variety of advanced technologies to
support the analysis of application, network, and server performance under a range of current and future operating conditions.
Many OPNET software products share a significant amount of core software based on an open architecture.
Riverbed delivers the most complete platform for Location-Independent Computing, turning location and distance into a
competitive advantage. The Riverbed Application Performance Platform™ allows IT to have the flexibility to host applications and
data in the most optimal locations while ensuring applications perform as expected, data is always available when needed, and
performance issues are detected and fixed before end users notice.
On October, 29, 2012, Riverbed acquired OPNET to build on Riverbed's strong heritage and experience in delivering solutions that
improve the performance of technology for business. OPNET has built its success on application performance management (APM)
and is recognized by a leading analyst firm as a leader in the magic quadrant for APM. Simulation is a very important modern
technology. It can be applied to different science, engineering, or other application fields for different purposes. Computer
assisted simulation can model hypothetical and real-life objects or activities on a computer so that it can be studied to see how
the system function. Different variables can be used to predict the behavior of the system. Computer simulation can be used to
assist the modeling and analysis in many natural systems. Typical application areas include physics, chemistry, biology, and
human-involved systems in economics, finance or even social science. Other important applications are in the engineering such
as civil engineering, structural engineering, mechanical engineering, and computer engineering. Application of simulation
technology into networking area such as network traffic simulation, however, is relatively new. After we get the observation data
from simulation experiments, the behavior of the network and protocols supported can then be observed and analyzed in a series
of offline test experiments.
WHY YOU SHOULD USE OPNET
Opnet is important for the following reasons.
1. Better Application Performance: Application Performance Management solutions and the visibility and actionable insight to
help deliver the application performance for better results.
2. End-user Experience Monitoring: Monitor and troubleshoot the ultimate measure of application performance.
3. Network Modeling Simulation: Analyzes and designs communication networks, model all network types and technologies.
Simulate networks compare impact of different technology on end-to-end behavior.
4. Network Performance Management: Whether day-to-day network issues, consolidating, building out, or experimenting for the
future, you need network modeling and simulation tools that deliver a complete picture of your network.
5. Packet Capture & Analysis: Helps understand the dependencies between your applications and network, be alerted to issues
before business is impacted, and accelerate troubleshooting.
6. Traffic Monitoring and Analytics: Easily troubleshoot and find the root cause of network and application issues before your end
users ever know there’s a problem.
7. Transaction Tracing: Monitor transactions to deliver high-performance applications.
8. Unified Communications: A proactive approach to monitoring unified communication service availability.
9. Business Productivity Increase: It improves application response times by solving applications network congestion and
supporting smooth application deployments since worker Are dependent on application to perform their work. It also cuts cost of
having to create a physical network at the first instance whereby errors could be made.
10. Operational efficiency Improvement: It provides structured, repeatable, diagnostic and validation functions which IT
organizations are dependent to solve technical problem.
11. Risk Reduction: It performs security checks, simulate failure and overload condition which organizations need to increase
their visibility required that minimize the risks.
12. Capital Cost Reduction: It provides an understanding and the performance of network to IT developers. This performance of
the network impact can cause achievement in investment with less expense.
13. Troubleshoot application problems in production, or validate readiness prior to deployment.
14. A comprehensive network engineering, operations, and planning suite that gives you full life-cycle coverage and best-in-class
network analysis.
With all these reasons which make OPNET important, network developers now have a tool that can make their work easier and
much more efficient, therefore they cannot afford to miss its great potentials which can change the way they work and give them
a better experience.
Riverbed provides its Network Simulation software for free to qualifying universities worldwide for academic research and
teaching. Riverbed delivers the most complete platform for Location-Independent Computing, turning location and distance into
a competitive advantage. The Riverbed Application Performance Platform™ allows IT to have the flexibility to host applications
and data in the most optimal locations while ensuring applications perform as expected, data is always available when needed,
and performance issues are detected and fixed before end users notice. Research in student learning indicates that skills are
more easily developed in context (Ramsden, 1988). However, the cost of providing dedicated networks makes this approach
financially unworkable therefore a OPNET could be helpful to analyse the behaviour and performance of communication
networks.
QUESTION AND ANSWER.
Below are some questions and answers.
1. Name the three main uses of OPNET?
2.What is a scenario?
3. What are events?
4. What is OPNET IT Guru?
5. List and explain three things that make Opnet important.
ANSWERS
1. The three main uses of opnet are simulating, modelling and analysis.
2. A scenario is a single instance of the network that represents a unique configuration of the network.
3. ƒEvents can be defined as specific activities that can occur at a particular time.
4. OPNET IT Guru is a network simulation application that provides a virtual network environment that can immitate, design and
test the network and its components.
5. i. Capital cost reduction.
ii. Network Performance Management.
iii. Better Application Performance
i. Capital Cost Reduction: It provides an understanding and the performance of a network to IT developers. This performance of
the network impact can cause achievement in investment with less expense.
ii. Network Performance Management: it helps in managing day-to-day network issues, consolidating, building out, or
experimenting for the future, you need network modeling and simulation tools that deliver a complete picture of your network.
iii. Better Application Performance: Application Performance Management solutions the visibility and actionable insight to help
deliver the application performance that users and business demand.
new communication networks is becoming more and more complicated due to the increasing offer of new products to renew and
increase networks. Hence for these reasons, it is necessary to use such a simulation tool with the characteristics of opnet. By
simulating changes such as technology migration, traffic growth and failures, opnet can help fix existing performance problems
before they occur. OPNET provides a virtual network environment where it is possible to analyze and optimize network
applications, configurations and traffic flow in nearly limitless range of “what if ” scenarios.
Simulation is the process of mimicking or imitating a real world process over time.
OPNET is a network simulator which contains a comprehensive development environment supporting the modeling and
performance evaluation of communication networks and distributed systems. OPNET has advantages over other major network
simulation software packages because of its ability to stay in touch with new communication network technologies, quality of
documentation, simulation platforms and whether the software meets all the needs for use in a data communications.
OPNET uses models that are specified in terms of objects, each with configurable sets of attributes. Models are hierarchical to
naturally parallel the structure of actual communication networks. The hierarchical approach allows for deep nesting of
subnetworks and nodes and large networks can be efficiently modeled.
OPNET has a wide variety of possibilities. Enables the possibility to simulate entire heterogeneous networks with various
protocols Development work was started in 1986 by MIL3 Inc. Originally, it was developed for the needs of millitary, but it has
grown to be a world leading commercial network simulation tool. OPNET is quite expensive for commercial usage but there are
also free licenses for educational purposes.
OPNET is a high level event based network level simulation tool. Originally built for the simulation of fixed networks. OPNET
contains a huge library of accurate models of commercially available fixed network hardware and protocols. Nowadays, the
possibilities for wireless network simulations are also very wide. Accurate radio transmission pipeline stage for the modeling of
the physical layer (radio interface).
The simulator has a lot of potentiality, but there exists typically a lack of the recent wireless systems. OPNET can be used as a
research tool or as a network design/analysis tool. With OPNET’s simulation tool it is possible to combine several low level
attributes and make series of simulations. The basic simulations with OPNET are done as a function of simulation timeto ensure
accurate network behavior. The level of event accuracy can be extended to be as detailed as needed. Simulation results as a
function of time are typically as such not suitable as scientific results, since statistical accuracy is needed. A certain situation can
be first verified with a simple simulation. OPNET is an event based network simulation tool. Using only simulations is quite
straightforward. Hierarchical structure, modeling is divided to three main domains: Network domain, Node domain and process
domain.
The Network DomainNetwork domain specifies the overall scope of the system to be simulated.
It is a high-level description of the objects contained in the system. Network model specifies the objects in the system as well as
their physical locations, interconnections and configurations.The Network Domain (sub-networks): An example of a sub-network
(WLAN) Fixed links sub-netnetwork nodes.The Network Domain (Mobility): Mobility trajectory whereby a node follows a
predetermined trajectory during simulation Mobility vector where a node moves according to a mobility vector defined with node
attributes, which can be modified during simulation and it also allows manipulation of node’s coordinates.
Node DomainThe node model specifies the internal structure of a network node. Typical nodes include workstations, packet
switches, satellite terminals, remote sensors. Nodes can be fixed, mobile or satellite type. A node can also be a special kind of
node representing e.g., an entire Ethernet or Token Ring network and its aggregate traffic as one entity
Process DomainƒA process is an instance of a process model. ƒProcesses can dynamically create child processes. With OPNET’s
simulation tool it is possible to combine several low level attributes and make series of simulation iterations.
The basic simulations with OPNET are done as a function of simulation time to ensure accurate network behavior. The level of
event accuracy can be extended to be as detailed as needed. On the Physical Layer Modeling, the physical layer is modeled with
pipeline stages, which are used to calculate step by step the total effect of the physical transmission medium including all the
interference caused by other users. OPNET is event based network simulation tool which is powerful but also demanding. Using
only simulations is quite straightforward • Modeling is done mainly in three levels Network Domain (top level), Upper levels hide
the complex structure of the lower level components, which can be totally invisible to the end user, Node Domain and Process
Domain. Different layers and functionalities can practically be modeled as accurately as needed with external model access.
WHAT ARE THE FEATURES OF OPNET?
OPNET simulator has the following features.
*Network Editor that specifies network topology and configure nodes and links.
*Node Editor with which you can create models of nodes by specifying internal structure and capabilities and create your own
devices
*Process Editor that develops models of decision-making processes representing protocols, algorithms, resource management,
operating systems, etc.
*Link Model Editor
Three domains: Network, node, and process ƒNode model specifies object in network while domain ƒProcess model specifies object
in node domain.
Network Domain: Network Objects
ƒNetwork models consist of nodes, links and subnets ƒNodes represent network devices and groups of devices, servers,
workstations, routers, LAN nodes, IP clouds, etc. ƒLinks represent point-to-point and bus links ƒIcons assist the user in quickly
locating the correct nodes and links ƒVendor models are distinguished by a specific color and logo for each company Generic
DevicesVendor Devices.
*Path Editor
*Packet Format Editor
*Scenario: is a single instance of the network. It represents a unique configuration of the network.
*An object palette is a graphical dialog box that displays a group of nodes and link models. Object palettes can be customized to
contain only the nodes and links that we need.ƒ
*Annotation Palette: ƒOpen by selecting Topology / Open Annotation Palette ƒAdd rectangles, circles, lines and text to models to
enhance their appearance ƒThis method is an effective way to graphically illustrate and document the changes made to a model ƒ
Does not affect analysis ƒAnnotations can be temporarily hidden
*Event-Driven Simulation
ƒEvents are specific activities that occur at a certain time. ƒOPNET simulations are event-driven . Simulation time advances when an
event occurs. ƒA different method might be to sample at regular intervals. ƒSimulation time advances only when an event with a
later time is processed from the event list ƒNo simulation time occurs during the execution of a process ƒNo time elapses during
transitions between states ƒA process model must always have an unforced (red) state so timecan advance zAvoid endless looping
between forced (green) states.
A radio link, established during a simulation, can be created between any radio transmitter-receiver channel pair. Satellite and
mobile nodes must use radio links. Fixed nodes may use radio links. A radio link is not drawn but is established if nodes contain
radio transceiver. Using OPNET it is possible to generate scenarios and create new models. It can simulate, design and test the
entire network including hardware devices
Such as server, switches, protocols, routers and individual applications, etc.
Network planner, IT manager and network administrator are now able to solve
All the difficult problem more effectively and validate changes before starting a
Real implementation. If we start implementing a network before simulate, it
Costs a lot to change any part of the network and waste time. All data are
Available to access network performance.
OPNET Modeler – Opnet modeler is the main tool for capacity planning and design.
WHAT IS OPNET USED FOR?
OPNET inherently has three main uses: modeling, simulating, and analysis. For modeling, it provides intuitive graphical
environment to create all kinds of models of protocols. For simulating, it uses 3 different advanced simulations technologies and
can be used to address a wide range of studies. For analysis, the simulation results and data can be analyzed and displayed very
easily through graphs or charts
For network simulation, more specifically, it means that the computer assisted simulation technologies are being applied in the
simulation of networking algorithms or systems by using software engineering. The application field is narrower than general
simulation and it is natural that more specific requirements will be placed on network simulations. For example, the network
simulations may put more emphasis on the performance or validity of a distributed protocol or algorithm rather than the visual
or real-time visibility features of the simulations. Moreover, since network technologies is keeping developing very fast and so
many different organizations participate in the whole process and they have different technologies or products running on
different software on the Internet. That is why the network simulations always require open platforms which should be scalable
enough to include different efforts and different packages in the simulations of the whole network. Internet has also a
characteristic that it is structured with a uniformed network stack (TCP/IP) that all the different layers technologies can be
implemented differently but with a uniformed interface with their neighbored layers. Thus the network simulation tools have to
be able to incorporate this feature and allow different future new packages to be included and run transparently without harming
existing components or packages. Thus the negative impact of some packages will have no or little impact to the other modules
or packages.
Network simulators are used by people from different areas such as academic researchers, industrial developers, and Quality
Assurance (QA) to design, simulate, verify, and analyze the performance of different networks protocols. They can also be used to
evaluate the effect of the different parameters on the protocols being studied. Generally a network simulator will comprise of a
wide range of networking technologies and protocols and help users to build complex networks from basic building blocks like
clusters of nodes and links. With their help, one can design different network topologies using various types of nodes such as
end-hosts, hubs, network bridges, routers, optical link-layer devices, and mobile units. Generally speaking, network simulators try
to model the real world networks. The principal idea is that if a system can be modeled, then features of the model can be
changed and the corresponding results can be analyzed. As the process of model modification is relatively cheap than the
complete real implementation, a wide variety of scenarios can be analyzed at low cost (relative to making changes to a real
network). However, network simulators are not perfect.
They can not perfectly model all the details of the networks. However, if well modeled, they will be close enough so as to give a
meaningful insight into the network under test, and how changes will affect its operation.
In the research area of computer and communications networks, simulation is a useful technique since the behavior of a network
can be modeled by calculating the interaction between the different network components. They can also be modeled by actually
or virtually capturing and playing back experimental observations from a real production networks. All kinds of environmental
attributes can also be modified in a controlled manner to assess how the network can behave under different parameters
combinations or different configuration conditions. Another characteristic of network simulation that worth noticing is that the
simulation program can be used together with different applications and services in order to observe end-to-end or other point-
to-point performance in the networks. In the network research area, it is very costly to deploy a complete test bed containing
multiple networked computers, routers and data links to validate and verify a certain network protocol or a specific network
algorithm. The network simulators in these circumstances save a lot of money and time in accomplishing this task. Network
simulators are also particularly useful in allowing the network designers to test new networking protocols or to change the
existing protocols in a controlled and reproducible manner.
Simulation is a very important modern technology. It can be applied to different science, engineering, or other application fields
for different purposes. Computer assisted simulation can model hypothetical and real-life objects or activities on a computer so
that it can be studied to see how the system function. Different variables can be used to predict the behavior of the system.
Computer simulation can be used to assist the modeling and analysis in many natural systems. Typical application areas include
physics, chemistry, biology, and human-involved systems in economics, finance or even social science. Other important
applications are in the engineering such as civil engineering, structural engineering, mechanical engineering, and computer
engineering. Application of simulation technology into networking area such as network traffic simulation, however, is relatively
new. For network simulation, more specifically, it means that the computer assisted simulation technologies are being applied in
the simulation of networking algorithms or systems by using software engineering. The application field is narrower than general
simulation and it is natural that more specific requirements will be placed on network simulations. For example, the network
simulations may put more emphasis on the performance or validity of a distributed protocol or algorithm rather than the visual
or real-time visibility features of the simulations. Moreover, since network technologies is keeping developing very fast and so
many different organizations participate in the whole process and they have different technologies or products running on
different software on the Internet. That is why the network simulations always require open platforms which should be scalable
enough to include different efforts and different packages in the simulations of the whole network. Thus the negative impact of
some packages will have no or little impact to the other modules or packages. However, network simulators are not perfect.
In the research area of computer and communications networks, simulation is a useful technique since the behavior of a network
can be modeled by calculating the interaction between the different network components (they can be end-host or network
entities such as routers, physical links or packets). After we get the observation data from simulation experiments, the behavior
of the network and protocols supported can then be observed and analyzed in a series of offline test experiments.
Another characteristic of network simulation that is worth noticing is that the simulation can be used together with different
applications and services in order to observe end-to-end or other point-to-point performance in the networks. Users can easily
visualize the workings of their simulated environment. Some of them may be text-based and can provide a less visual or intuitive
interface, but may allow more advanced forms of customization. Others may
OPNET is the registered commercial trademark and the name of product presented by OPNET Technologies incorporation. It
became one of the most famous and popular commercial network simulators by the end of 2008. Because of has been used for a
long time in the industry, it became mature and has occupied a big market share.
It can be flexibly used to study communication networks, devices, protocols, and applications. Because of the fact of being a
commercial software provider, OPNET offers relatively much powerful visual or graphical support for the users.
OPNET is based on a mechanism called discrete event system which means that the system behavior can simulate by modeling
the events in the system in the order of the scenarios the user has set up. Hierarchical structure is used to organize the networks.
As other network simulators, OPNET also provides for users to define the packet format of the protocol. As of all, OPNET is a
popular simulator used in industry for network research and development. Because of the consistent endeavor and operation of
OPNET Inc., OPNET is becoming mature and its product maintain a high acknowledge in the industry. Moreover, OPNET always
keeps an eye on the most recent users's requirements and keeps improving their product which make it very competitive
compared with other commercial network simulators in the near expectable future.
What is the history of OPNET Technologies, Inc?
OPNET Technologies, Inc. is a Delaware corporation that was incorporated in November 1988. The Company is a provider of
software products and related services for managing applications and networks. Its software products address application
performance management, network planning, engineering and operations, and network research and development. The
Company's customers include corporate enterprises, government and defense agencies, network service providers, and network
equipment manufacturers. The Company's software products and related services are designed to help its customers make better
use of resources, reduce operational problems, and improve competitiveness. It focuses on analytics and producing actionable
results. It is engaged in the development and sale of computer software programs and related services. The Company's
operations are principally in the United States, and it has subsidiaries in Belgium, France, Germany, the United Kingdom and
Singapore. The Company markets software products and related services in North America primarily through a direct sales force
and, to a lesser extent, several resellers and original equipment manufacturers. Internationally, the Company conducts research
and development through a wholly-controlled subsidiary in Ghent, Belgium and markets software products and related services
through wholly-owned subsidiaries in Paris, France; Mainz, Germany; Slough, United Kingdom; and Singapore; a sales office in
Beijing, China; third-party distributors; and value-added resellers. Its software products use a variety of advanced technologies to
support the analysis of application, network, and server performance under a range of current and future operating conditions.
Many OPNET software products share a significant amount of core software based on an open architecture.
Riverbed delivers the most complete platform for Location-Independent Computing, turning location and distance into a
competitive advantage. The Riverbed Application Performance Platform™ allows IT to have the flexibility to host applications and
data in the most optimal locations while ensuring applications perform as expected, data is always available when needed, and
performance issues are detected and fixed before end users notice.
On October, 29, 2012, Riverbed acquired OPNET to build on Riverbed's strong heritage and experience in delivering solutions that
improve the performance of technology for business. OPNET has built its success on application performance management (APM)
and is recognized by a leading analyst firm as a leader in the magic quadrant for APM. Simulation is a very important modern
technology. It can be applied to different science, engineering, or other application fields for different purposes. Computer
assisted simulation can model hypothetical and real-life objects or activities on a computer so that it can be studied to see how
the system function. Different variables can be used to predict the behavior of the system. Computer simulation can be used to
assist the modeling and analysis in many natural systems. Typical application areas include physics, chemistry, biology, and
human-involved systems in economics, finance or even social science. Other important applications are in the engineering such
as civil engineering, structural engineering, mechanical engineering, and computer engineering. Application of simulation
technology into networking area such as network traffic simulation, however, is relatively new. After we get the observation data
from simulation experiments, the behavior of the network and protocols supported can then be observed and analyzed in a series
of offline test experiments.
WHY YOU SHOULD USE OPNET
Opnet is important for the following reasons.
1. Better Application Performance: Application Performance Management solutions and the visibility and actionable insight to
help deliver the application performance for better results.
2. End-user Experience Monitoring: Monitor and troubleshoot the ultimate measure of application performance.
3. Network Modeling Simulation: Analyzes and designs communication networks, model all network types and technologies.
Simulate networks compare impact of different technology on end-to-end behavior.
4. Network Performance Management: Whether day-to-day network issues, consolidating, building out, or experimenting for the
future, you need network modeling and simulation tools that deliver a complete picture of your network.
5. Packet Capture & Analysis: Helps understand the dependencies between your applications and network, be alerted to issues
before business is impacted, and accelerate troubleshooting.
6. Traffic Monitoring and Analytics: Easily troubleshoot and find the root cause of network and application issues before your end
users ever know there’s a problem.
7. Transaction Tracing: Monitor transactions to deliver high-performance applications.
8. Unified Communications: A proactive approach to monitoring unified communication service availability.
9. Business Productivity Increase: It improves application response times by solving applications network congestion and
supporting smooth application deployments since worker Are dependent on application to perform their work. It also cuts cost of
having to create a physical network at the first instance whereby errors could be made.
10. Operational efficiency Improvement: It provides structured, repeatable, diagnostic and validation functions which IT
organizations are dependent to solve technical problem.
11. Risk Reduction: It performs security checks, simulate failure and overload condition which organizations need to increase
their visibility required that minimize the risks.
12. Capital Cost Reduction: It provides an understanding and the performance of network to IT developers. This performance of
the network impact can cause achievement in investment with less expense.
13. Troubleshoot application problems in production, or validate readiness prior to deployment.
14. A comprehensive network engineering, operations, and planning suite that gives you full life-cycle coverage and best-in-class
network analysis.
With all these reasons which make OPNET important, network developers now have a tool that can make their work easier and
much more efficient, therefore they cannot afford to miss its great potentials which can change the way they work and give them
a better experience.
Riverbed provides its Network Simulation software for free to qualifying universities worldwide for academic research and
teaching. Riverbed delivers the most complete platform for Location-Independent Computing, turning location and distance into
a competitive advantage. The Riverbed Application Performance Platform™ allows IT to have the flexibility to host applications
and data in the most optimal locations while ensuring applications perform as expected, data is always available when needed,
and performance issues are detected and fixed before end users notice. Research in student learning indicates that skills are
more easily developed in context (Ramsden, 1988). However, the cost of providing dedicated networks makes this approach
financially unworkable therefore a OPNET could be helpful to analyse the behaviour and performance of communication
networks.
QUESTION AND ANSWER.
Below are some questions and answers.
1. Name the three main uses of OPNET?
2.What is a scenario?
3. What are events?
4. What is OPNET IT Guru?
5. List and explain three things that make Opnet important.
ANSWERS
1. The three main uses of opnet are simulating, modelling and analysis.
2. A scenario is a single instance of the network that represents a unique configuration of the network.
3. ƒEvents can be defined as specific activities that can occur at a particular time.
4. OPNET IT Guru is a network simulation application that provides a virtual network environment that can immitate, design and
test the network and its components.
5. i. Capital cost reduction.
ii. Network Performance Management.
iii. Better Application Performance
i. Capital Cost Reduction: It provides an understanding and the performance of a network to IT developers. This performance of
the network impact can cause achievement in investment with less expense.
ii. Network Performance Management: it helps in managing day-to-day network issues, consolidating, building out, or
experimenting for the future, you need network modeling and simulation tools that deliver a complete picture of your network.
iii. Better Application Performance: Application Performance Management solutions the visibility and actionable insight to help
deliver the application performance that users and business demand.
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