Introduction to NS2 -Network Simulator-

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Introduction to NS2-Network Simulator-

• -Prepared by Changyong Jung

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Contents

• Overview
• How to Install
• OTCL The User Language
• Event Scheduler
• Packet
• Simulation Example

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Overview

• What is NS2?
• - Event driven network simulator
• - Developed at UC Berkely
• - Implements network protocols
• 1) TCP, UPD
• 2) Traffic source mechanism FTP, TELNET,
  Web, CBR and VBR
• 3) Router Queue management mechanism Drop
  Tail, RED, CBQ
• 4) Routing Algorithm Dijkstra, and etc
• 5) Multicasting, Mac layer protocols for
  LAN

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Overview

• Background on the ns Simulator
• - based on two languages( an object-oriented
  simulator (C), and OTcl (object-oriented Tcl)
  interpreter.
• - has rich library of network and protocol
  object
• - Compiled C hierarchy gives efficiency in
  simulation and faster execution times.
• - With OTcl script provided by user, a network
  topology is simulated.

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Overview

• Ns2 is event simulator where the advance of time
  depends on the timing of events which are
  maintained by a scheduler.
• Event an object in C hierarchy.
• unique ID, Scheduled time,
• pointer to an object
• Scheduler maintains ordered data structure with
  the events to be executed and fires them one by
  one, invoking the handler of the event.

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How to Install-Window XP-

• Go to Website
• http//nsnam.isi.edu/nsnam/index.php/Running_Ns_
  and_Nam_Under_Windows_9x/2000/XP_Using_Cygwin
• Read Requirements and Installation Tips
  Carefully.
• Download cygwin.exe from http//www.cygwin.com/
• Click the cygwin.exe

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How to Install

• Cygwin Installation

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How to Install
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How to Install

• Select browse for cygwin file( I selected as
  default)

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How to Install

• Local package directory (I recommend c\cygwin).

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How to Install

• Select to Install all ( I recommend it)
• You can select install, default, uninstall,
  install, and reinstall behind the first line
  all. If you select install, then all sub
  items will be automatically selected. Otherwise
  you may lose some items.

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How to Install

• Select download site

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How to Install

• Installing

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How to Install

• Finishing Installing

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How to Install

• NS2 Installation
• Download ns-allinone-2.29.2.tar.gz from Website
  and Save it to the c/cygwin /usr/local
• Unpack it tar xvfz ns-allinone-2.29.2.tar.gz
• Click on desktop icon cygwin

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How to Install
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How to Install

• Type cd .. to go to the upper folder(cd must
  be low case. And there is one space between d
  and .)
• Type cd .. again.

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How to Install

• cd usr, go to folder usr
• cd local, go to folder local

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How to Install

• Find install.exe

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How to Install

• Start to run the installation ./install

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How to Install

• Installing

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How to Install

• Installing

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How to Install

• Configure system variables and library paths
• After finishing installing, following window
  appears

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How to Install

• Configure system variables
• Go to My computer and click view system
  information

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How to Install

• Go to advanced Tab and Click Environmental
  variables

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How to Install
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How to Install

• Highlight path which is system variable box
  and press the Edit button.

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How to Install
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How to Install

• Add the following path separated with make
  sure to not change the existing path.
• /usr/local/ns-allinone-2.29.2/bin
• /usr/local/ns-allinone-2.29.2/tcl8.4.11/unix
• /usr/local/ns-allinone-2.29.2/tk8.4.11/unix

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How to Install

• Go to cygwin and type the following content
• Export LD_LIBRARY_PATH/usr/local/ns-allinone-2.2
  9/otcl-1.11
• Export LD_LIBRARY_PATH/usr/local/ns-allinone-2.2
  9/lib
• Export TCL_LIBRARY_PATH/usr/local/ns-allinone-2.2
  9/tcl8.4.11/library

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How to Install
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OTcl The User Language

• NS2 is basically an OTcl interpreter with network
  simulation object libraries
• Very simple syntax and easy integration with
  other languages.
• Characteristics
• - fast development
• - provide graphic interface
• - compatible with many platforms
• - flexible for integration
• - easy to use
• - free

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OTcl The User Language

• Example

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OTcl The User Language

• Proc define a procedure, followed by an
  procedure name and arguments
• Set assign a value to a variable
• expr to make the interpreter calculate the
  value of expression within the bracket
• To assign to variable x the value that variable a
  has, then write set x a.
• Put prints out

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OTcl The User Language
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Event Scheduler

• Main users of an event scheduler are network
  components that simulate packet-handling delay or
  that need time

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Event Scheduler

• Two different types of event schedulers
• - real time for emulation which allow the
  simulator to interact with a real network
• - non-real time three implementations are
  available (Heap, List, Calendar). The default is
  set as Calendar

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Event Scheduler

• Example
• . . .set ns new Simulatorns use-scheduler
  Heap. . .
• . . .set ns new Simulatorns use-scheduler
  Heapns at 300.5 "complete_sim". . .proc
  complete_sim . . .

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Packet

• NS2 packet is composed of a stack of headers and
  optional dataspace.
• Packet format is initialized when a Simulator
  object is created. So, a network object can
  access any header in the stack of a packet it
  processes using corresponding offset value.

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Packet
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Simple Simulation Implement
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Simple Simulation Implement
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Simple Simulation Implement

• Click on desktop icon cygwin
• Make sure to put the exe files under
  C\cygwin\usr\local
• Do the following steps to execute example.

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Simple Simulation Implement
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Simple Simulation Implement

• However you will fail to run the ns-simple.tcl
  with the displayed notice. This is because you
  did not open XWin yet

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Simple Simulation Implement

• Open Xwin from C\cygwin\usr\X11R6\bin. If
  everything is fine, you will then get the
  following figures.

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Simple Simulation Implement

• Yet you may get the following warning messages

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Simple Simulation Implement

• That means some components missed. You can then
  copy these files from C\cygwin\bin to
  C\cygwin\usr\X11R6\bin
• After you open X11, you may still can not run
  ns-simple.tcl

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Simple Simulation Implement

• The following command can solve this issue
• export DISPLAY0.0

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Simple Simulation Implement
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Simple Simulation Implement

• Run ns-simple.tcl

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Simple Simulation Implement

• DONE !!!

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Simple Simulation Implement
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• Thank You.