IntroNS2

Introduction to NS2-Network Simulator-

-Prepared by Changyong Jung

ContentsOverviewHow to InstallOTCL The User LanguageEvent SchedulerPacketSimulation Example

OverviewWhat 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

OverviewBackground 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.

OverviewNs2 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 objectScheduler maintains ordered data structure with the events to be executed and fires them one by one, invoking the handler of the event.

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_CygwinRead Requirements and Installation Tips Carefully.Download cygwin.exe from http://www.cygwin.com/Click the cygwin.exe

How to InstallCygwin Installation

How to Install

How to InstallSelect browse for cygwin file( I selected as default)

How to InstallLocal package directory (I recommend c:\cygwin).

How to InstallSelect 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.

How to InstallSelect download site

How to InstallInstalling

How to InstallFinishing Installing

How to InstallNS2 InstallationDownload ns-allinone-2.29.2.tar.gz from Website and Save it to the c:/cygwin /usr/localUnpack it: tar xvfz ns-allinone-2.29.2.tar.gzClick on desktop icon cygwin

How to Install

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

How to Installcd usr, go to folder usrcd local, go to folder local

How to InstallFind install.exe

How to InstallStart to run the installation ./install

How to InstallInstalling

How to InstallConfigure system variables and library pathsAfter finishing installing, following window appears

How to InstallConfigure system variablesGo to My computer and click view system information

How to InstallGo to advanced Tab and Click Environmental variables

How to Install

How to InstallHighlight path which is system variable box and press the Edit button.

How to Install

How to InstallAdd 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

How to InstallGo to cygwin and type the following contentExport LD_LIBRARY_PATH=/usr/local/ns-allinone-2.29/otcl-1.11Export LD_LIBRARY_PATH=/usr/local/ns-allinone-2.29/libExport TCL_LIBRARY_PATH=/usr/local/ns-allinone-2.29/tcl8.4.11/library

How to Install

OTcl The User LanguageNS2 is basically an OTcl interpreter with network simulation object librariesVery 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

OTcl The User LanguageExample

OTcl The User LanguageProc: 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 bracketTo assign to variable x the value that variable a has, then write set x $a.Put: prints out

OTcl The User Language

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

Event SchedulerTwo 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

Event SchedulerExample . . . set ns [new Simulator] $ns use-scheduler Heap . . .

. . . set ns [new Simulator] $ns use-scheduler Heap $ns at 300.5 "complete_sim" . . . proc complete_sim {} { . . . }

PacketNS2 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.

Packet

Simple Simulation Implement

Simple Simulation ImplementClick on desktop icon cygwinMake sure to put the exe files under C:\cygwin\usr\localDo the following steps to execute example.

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

Simple Simulation ImplementOpen Xwin from C:\cygwin\usr\X11R6\bin. If everything is fine, you will then get the following figures.

Simple Simulation ImplementYet you may get the following warning messages:

Simple Simulation ImplementThat means some components missed. You can then copy these files from C:\cygwin\bin to C:\cygwin\usr\X11R6\binAfter you open X11, you may still can not run ns-simple.tcl

Simple Simulation ImplementThe following command can solve this issue export DISPLAY=:0.0

Simple Simulation ImplementRun ns-simple.tcl

Simple Simulation ImplementDONE !!!

Thank You.

IntroNS2

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