1 NS-2 Tutorial COMP R2 University of Manitoba March 4, 2009

2 Goal and Outline Goal of this tutorial  Lead you to get started using NS-2 Outline  Introduction - What’s NS?  Steps in Using NS-2 (through examples)  Development and Your Project

3 What’s NS? NS is a packet-level simulator  Started with Keshav’s REAL in 1989  Been revised in Berkeley, then others Overview  Major engine (network components) written in C++  User-interface is tcl script

4 My First Tcl Script

5 Test it out! Go to 2/TUTORIAL

6 My First OTcl Script

7 NS-2 Simulated Components Protocols  TCP, UDP, DCCP, SCTP, TFRC, Wi-Fi, etc. Network model  Nodes, links, topology, channel schedulers, buffer management, etc. Traffic model  Applications: FTP, CBR, MPEG, etc.  Traffic traces

8 NS-2 Simulated Components (II) All implemented by students/researchers like you and me Each release has a few more contributed components added Many are still being developed Well documented steps to use and to add to NS-2

9 General Steps In Using NS-2 Obtaining NS-2 (made available for you) Writing an OTcl script. E.g., “a.tcl” Run the simulation. Just type “ns a.tcl” Post-process the trace generated Plot graphs and include in your papers

10 Obtaining NS-2 Available to you here in CS Linux version 2.33 installed on neram-02 (a networks lab Linux machine) Each student is given a separate complete copy of NS-2  me if you don’t know how to access yours

11 Obtaining NS-2 (for your home PC) Available for both Linux and Windows For Windows, you need VMware or cygwin For Linux, install all-in-one package requires only four commands  tar xzvf ns-allinone-2.33.tar.gz  cd ns-allinone-2.33 ./install  source setup.csh (Note this script was written by our system admin Gilbert, you may need to copy it over and “customize” it a little bit) You are ready to go

12 Writing An OTcl Script Use NS-2, take a look at “ns-simple.tcl”

13 Writing An OTcl Script (II) Add to NS-2  Write a new network layer component  Write a new transport layer protocol  Write a new application Steps  Writing new components in.cc and.h (often free implementations are available)  Add to existing header files in package  Add to Makefile and re-compile

14 Add To NS-2 Step-by-step instructions for a few examples available in “NS by Example” from WPI  On Transport, Application, and Network Layers respectively Web site 

15 Run The Simulation Plug in the trace file names

16 Run the Simulation to Collect Traces Entire packet level event trace dump to file

17 Post-Process the Trace Generated Through scripting languages such as Perl, awk, (ba)sh (shell scripts) Or spread sheet such as Excel See example “ns-simple-trace.tcl” to generate trace “out.tr” Perl and awk combined to produce “jitter.txt”

18 Plot the Graphs Gnuplot, very handy tool to give nice graphs See example “gp”, a Gnuplot script that I wrote The generated.ps file can be easily added to LaTeX for paper / report writing

19 Development Editor (you need a comfortable way to edit files under Linux)  Vi, Emacs, pico, … what else do people use? Make  A very simple utility to automate compilation

20 Your Course Project Some tools to play with  OTcl, editor, make, perl, gnuplot  nam to avoid (an animator not essential to simulation) Need to add to NS-2?  Search for existing implementations on the net first Have fun!