Mosc2011 Ns2 Final

8/3/2019 Mosc2011 Ns2 Final

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Innovative As ect of O en SourceNetwork Simulator v2 (NS2)

Presented by:

Adib M.Monzer Habbal MIEEE

InterNetWorks Research GroupUniversiti Utara Malaysia

http://stafweb.uum.edu.my/adib/[email protected]


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Objectives of this presentation

Learn fundamentals of network simulation

Introduce one of the most useful tools in

networking research called NS2.

Discuss practical innovations of NS2

5 July 2011 MOSC2011 Innovative Aspect of Open SourceNetwork Simulator v2 (NS2)

Slide 2


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What is simulation?

system under study

(has deterministic rules

governing its behavior)

exogenous inputs

to system

(the environment)

system boundary

real life


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computer program

simulates deterministic

rules governing behavior

psuedo random inputs

to system

(models environment)

program boundary

observer

simulated life


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Why Simulation?

real-system not available, is complex/costly ordangerous(eg: space simulations, flightsimulations)

quickly evaluate design alternatives(eg:

different system configurations)

evaluate complex functionsfor which closedform formulas or numerical techniques notavailable


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Network Simulation

has been the main research methodology used byresearchers working on the core of Internet

development

number of credible published research works has

been done usin network simulation

e.g. those that appear in IEEE/ACM journals and

proceedings

used to ensure that functional requirements ofnew network elements (e.g.. new protocols) can

be achieved and are feasible


Slide 5


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Classes of Network Simulation

Law and Kelton classify network simulations into thefollowing classes:

Static simulation - simulation using representation of asystem at a particular time

Dynamic simulation - simulation using representation of a

system as it evolves over time Deterministic simulation - simulation usin a model that does

not contain any probabilistic (i.e. random) components

Stochastic simulation - simulation using a model that containprobabilistic (i.e., random) components

Continuous simulation - simulation involving an infinite

number of events Discrete (event) simulation - simulation using finite number of

events that take place during simulation at discrete times


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Network Simulation Packages/Tools

Open source tools: Network Simulator v2 (NS2),

Global Mobile Simulator (GloMoSim),

OMNeT++

OPNET

PacketStorm (emulator)

More tools at:

http://www.icir.org/models/simulators.html


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The NS2 Simulator

NS2 stands for Network Simulator version 2.

NS2:

Is a dynamic, stochastic, and discrete event

network simulator.arge e a ne wor ng researc

works at packet level.

is primarily Unix based.


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The NS2 Simulator

It is an open source

available at source forge

http://www.isi.edu/nsnam/ns/


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The NS2 Simulator


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The NS2 Simulator


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The NS2 Simulator


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The NS2 Simulator


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NS2 Utilities

MAC layer

Wireless network

Wired Network

TDMA

CDMA

IEEE 802.x


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Ad Hoc Network


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Practical Innovations of NS2

Abstraction

Challenges

All simulators adopt some level ofabstraction when choosing what to simulate.

Solution

NS2 supports several levels of abstraction.

NS2 employs a split-programming model


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Abstraction


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Scenario generation

Challenges,

Traffic models that specify sender and receiver locations and demands,and

Network dynamics that include node and link failures.

Solution

NS2 meets these needs by providing

a library of predefined topologies and

using packages such as the Georgia Tech models (GT-ITM) togenerate random topologies.


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Scenario generation


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Emulation

Challenges Most simulators are confined to a single

simulated world that employs only theprotocols and algorithms in the simulator.

Solution

NS2 includes an emulation interface thatpermits network traffic to pass between real-world network nodes and the simulator.


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Emulation


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Visualization

Challenges esearc ers nee oo s a e p em un ers an e comp ex

behavior in network simulation.

Merely providing tables of summary performance numbers doesnot adequately describe a networks behavior

Solution

nam

Xgraph

Gnuplot

JDNA


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Visualization using XGraph


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Visualization using JDNA


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Extensibility

Challenges The simulator must be easy to extend if its

users are to add new functionality, explore arange of scenarios, and study new protocols.

Solution

Nss object-oriented structure makes it fairlyeasy to implement new or existing protocols.


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Education

Challenges The traditional education methods have the ubiquitous

disadvantage of that teachers are very toilsome toexplain the protocols and student are also very hard tounderstand them.

Solution

NS2 has achieved some beneficial effect in the educationpractice


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Validation

Challenges The need to compare new network variants

demands validated protocols.

Solution

NS2 validates protocols to the degree theirmaturity warrants.

NS2 includes many automated test suites


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NS2 Documentations

NS2 Manual http://www.isi.edu/nsnam/ns/doc/index.html

Very detailed, useful when looking for somethingspecific, like:

How do I make my routing strategy to be Distance

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What are the shadowing models available for wireless?How do I select them?



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NS2 Documentations

NS2 Tutorial by Marc Greis http://www.isi.edu/nsnam/ns/tutorial/index.html

Good starting point for understanding the overall

structure of NS2

Examples:

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What is the relation between c++ classes and Otcl

classes?

basic info on instantiating NS2 instance, tcl scripting



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NS2 Documentations

NS2 for beginners http://www-sop.inria.fr/maestro/personnel/Eitan.Altman/COURS-NS/n3.pdf

More detailed than Marc Greis Tutorial

Examples:

What does each line of a tcl script do?

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Most common examples of trace formats that are

useful



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Tcl Documentations

Tcl Tutorial http://www.tcl.tk/man/tcl8.5/tutorial/tcltutorial.html

Tcl Manual

All commands and their explanation

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. . . .



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Bug-Fixing When things go wrong..

Googling for the problem! Extensive NS2 mailing lists

Chances are that other people have had the same

problem are very high

Responsive forums

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Bug-Fixing When things go wrong..

NS2 in-built examples Extensive inbuilt examples

diffing with the examples helps a lot

Sometimes a good idea to start from a script that does

something similar

Slide 375 July 2011 MOSC2011 Innovative Aspect of Open SourceNetwork Simulator v2 (NS2)


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Conclusion

In this presentation, we have: Explainedthe fundamental of network simulation

DemonstratedNS2 for simulation-based network

performance research


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Discussedpractical innovations of NS2


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Documents

Mosc2011 Ns2 Final