1. Introduction to NS2 -Network Simulator- -Prepared by Changyong Jung

2. Contents Overview How to Install OTCL – The User Language Event Scheduler Packet Simulation Example

3. 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

4. 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.

5. 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.

6. 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/ http://www.cygwin.com/ Click the “cygwin.exe”

7. How to Install Cygwin Installation

8. How to Install

9. Select browse for “cygwin” file( I selected as “default”)

10. How to Install Local package directory (I recommend c:\cygwin).

11. 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.

12. How to Install Select download site

13. How to Install Installing

14. How to Install Finishing Installing

15. 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”

16. How to Install

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

18. How to Install “cd usr”, go to folder “usr” “cd local”, go to folder “local”

19. How to Install Find “install.exe”

20. How to Install Start to run the installation “./install”

21. How to Install Installing

22. How to Install Installing

23. How to Install Configure system variables and library paths After finishing installing, following window appears

24. How to Install Configure system variables Go to “My computer” and click “view system information”

25. How to Install Go to “advanced” Tab and Click “Environmental variables”

26. How to Install

27. Highlight “path” which is “system variable” box and press the “Edit” button.

28. How to Install

29. 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

30. How to Install Go to cygwin and type the following content Export LD_LIBRARY_PATH=/usr/local/ns- allinone-2.29/otcl-1.11 Export LD_LIBRARY_PATH=/usr/local/ns- allinone-2.29/lib Export TCL_LIBRARY_PATH=/usr/local/ns- allinone-2.29/tcl8.4.11/library

31. How to Install

32. 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

33. OTcl – The User Language Example

34. 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

35. OTcl – The User Language

36. Event Scheduler Main users of an event scheduler are network components that simulate packet-handling delay or that need time

37. 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

38. Event Scheduler Example... 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 {} {... }

39. 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.

40. Packet

41. Simple Simulation Implement

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

44. Simple Simulation Implement

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

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

47. Simple Simulation Implement Yet you may get the following warning messages:

48. 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”

49. Simple Simulation Implement The following command can solve this issue export DISPLAY=:0.0

50. Simple Simulation Implement

51. Run “ns-simple.tcl”

52. Simple Simulation Implement DONE !!!

53. Simple Simulation Implement

54. Thank You….