Easy way to learn ns2

1. Introduction To NS-2Introduction To NS-2
By
Arshad Ahmad Khan Mohammad
Part Time Research Scholar (CNIS)
KL University, Andhra Pradesh
India,
.

2. Outline Of PresentationOutline Of Presentation
 IntroductionIntroduction
 InstallationInstallation
 ArchitectureArchitecture
 Tcl & Otcl ExamplesTcl & Otcl Examples
 Simulation StepsSimulation Steps
 Examples (Wired)Examples (Wired)
 Examples (Wireless)Examples (Wireless)

3. IntroductionIntroduction
 About NS2About NS2
 Advantages of NS2Advantages of NS2
 NS2 Supported Protocols(Wired &NS2 Supported Protocols(Wired &
Wireless)Wireless)

4. Arshad KhanArshad Khan 44
Network Simulation *Network Simulation *
Motivation:Motivation:
 Learn fundamentalsLearn fundamentals
of evaluatingof evaluating
networknetwork
performance viaperformance via
simulationsimulation
•
Overview:Overview:
 fundamentals offundamentals of
discrete eventdiscrete event
simulationsimulation
 ns-2 simulationns-2 simulation

5. Arshad KhanArshad Khan 55
Why Simulation? *Why Simulation? *
 real-system notreal-system not available, is complex/costly oravailable, is complex/costly or
dangerousdangerous ((eg: space simulations, flighteg: space simulations, flight
simulations)simulations)
 quickly evaluate designquickly evaluate design alternativesalternatives (eg:(eg:
different system configurations)different system configurations)
 evaluateevaluate complex functionscomplex functions for which closedfor which closed
form formulas or numerical techniques notform formulas or numerical techniques not
availableavailable

6. Arshad KhanArshad Khan 66
Simulation: advantages/drawbacks*Simulation: advantages/drawbacks*
 advantages:advantages:
• sometimes cheapersometimes cheaper
• find bugs (in design) in advancefind bugs (in design) in advance
• generality:generality: over analytic/numerical techniquesover analytic/numerical techniques
• detail:detail: can simulate system details at arbitrarycan simulate system details at arbitrary
levellevel
 drawbacks:drawbacks:
• caution: does model reflect realitycaution: does model reflect reality
• large scale systems: lots of resources tolarge scale systems: lots of resources to
simulate (especially accurately simulate)simulate (especially accurately simulate)
• may be slow (computationally expensive – 1may be slow (computationally expensive – 1
min real time could be hours of simulated time)min real time could be hours of simulated time)
• art: determining right level of model complexityart: determining right level of model complexity
• statistical uncertainty in resultsstatistical uncertainty in results

7. OverviewOverview
 Ns2 is event simulator where the advanceNs2 is event simulator where the advance
of time depends on the timing of eventsof time depends on the timing of events
which are maintained by a scheduler.which are maintained by a scheduler.
 Event – an object in C++ hierarchy.Event – an object in C++ hierarchy.
unique ID, Scheduled time,unique ID, Scheduled time,
pointer to an objectpointer to an object
 Scheduler – maintains ordered dataScheduler – maintains ordered data
structure with the events to be executedstructure with the events to be executed
and fires them one by one, invoking theand fires them one by one, invoking the
handler of the event.handler of the event.

8. Arshad KhanArshad Khan
Discrete event simulatorDiscrete event simulator
 ns-2 is an discrete event driven simulationns-2 is an discrete event driven simulation
• Physical activities are translated to eventsPhysical activities are translated to events
• Events are queued and processed in the order of theirEvents are queued and processed in the order of their
scheduled occurrencesscheduled occurrences
• Time progresses as the events are processedTime progresses as the events are processed
1 2
Time: 1.5 sec Time: 1.7 sec
Time: 1.8 secTime: 2.0 sec

9. 99
Event Driven SimulationEvent Driven Simulation
TX Pkt Event
@ 1.5sec
Node 1
Module
Node 2
Module
TX Pkt Event
@ 1.5sec
RX Pkt Event
@ 1.7sec
RX Pkt Event
@ 1.7sec
TX Ack Event
@ 1.8sec
TX Ack Event
@ 1.8sec
RX Ack Event
@ 2.0sec
RX Ack Event
@ 2.0sec
Event Queue
Simulation Finished!

10. 1010
Discrete Event ExamplesDiscrete Event Examples
Consider two nodes
on an Ethernet:
A B
simple
queuing
model:
t=1, A enqueues pkt on LAN
t=1.01, LAN dequeues pkt
and triggers B
detailed
CSMA/CD
model:
t=1.0: A sends pkt to NIC
A’s NIC starts carrier sense
t=1.005: A’s NIC concludes cs,
starts tx
t=1.006: B’s NIC begins reciving pkt
t=1.01: B’s NIC concludes pkt
B’s NIC passes pkt to app

11. 1111
ns-2 Environmentns-2 Environment
Simulation
Scenario
Tcl Script
C++
Implementation
1 2
set ns_ [new Simulator]
set node_(0) [$ns_ node]
set node_(1) [$ns_ node]
class MobileNode : public Node
{
friend class PositionHandler;
public:
MobileNode();
•
•
}

12. 1212
LanguagesLanguages
 C++ forC++ for datadata
• Per-packet processing, the core ofPer-packet processing, the core of nsns
• Fast to run, detailed, complete controlFast to run, detailed, complete control
 OTcl forOTcl for controlcontrol
• Simulation descriptionSimulation description
• Periodic or triggered actionsPeriodic or triggered actions
• Manipulating existing C++ objectsManipulating existing C++ objects
• Faster to write and changeFaster to write and change
 (a matter of opinion)(a matter of opinion)

13. Working with NSWorking with NS
 NSNS
an OTcl interpreter with network librariesan OTcl interpreter with network libraries
InvocationInvocation
 Interactive modeInteractive mode
nsns
% (This is the ns prom)% (This is the ns prom)
 Batch modeBatch mode
ns tclfile.tclns tclfile.tcl

14. ““Hello World” Example (Interactive)Hello World” Example (Interactive)
 nsns
 % puts "Hello World!!!"% puts "Hello World!!!"
 Hello World!!!Hello World!!!
 % puts "Hello NS newbie"% puts "Hello NS newbie"
 Hello NS newbieHello NS newbie
 %exit%exit

15. ““Hello World” Example (Batch)Hello World” Example (Batch)
 Hello.tclHello.tcl
puts "Hello World!!!"puts "Hello World!!!"
puts "Hello NS newbie"puts "Hello NS newbie"
 InvocationInvocation
ns hello.tclns hello.tcl
"Hello World!!!“"Hello World!!!“
"Hello NS newbie""Hello NS newbie"

16. OTclOTcl
 NS is an interpreter of OtclNS is an interpreter of Otcl
 We communicate with NS by OtclWe communicate with NS by Otcl
 We need to know how to use OTclWe need to know how to use OTcl
Its syntaxIts syntax
Basic commandsBasic commands

17. OTcl BasicsOTcl Basics
 set: Assign a value to a variableset: Assign a value to a variable
 $x: The value of variable x$x: The value of variable x
 [ … ]: Run command and return result[ … ]: Run command and return result
 [expr …]: Calculate the value of expression[expr …]: Calculate the value of expression
 set x $a: Assign value of a to variable xset x $a: Assign value of a to variable x
 puts … : print outputs … : print out
 proc: Define a procedureproc: Define a procedure
 gets stdin x: Read variable x from stdingets stdin x: Read variable x from stdin
Be careful about spacesBe careful about spaces

18. OTcl: Example 1OTcl: Example 1
puts "Enter 1th operand"puts "Enter 1th operand"
gets stdin agets stdin a
puts "Enter 2th operand"puts "Enter 2th operand"
gets stdin bgets stdin b
set sum [expr $a + $b]set sum [expr $a + $b]
set diff [expr $a - $b]set diff [expr $a - $b]
puts "$a + $b = $sum"puts "$a + $b = $sum"
puts "$a - $b = $diff"puts "$a - $b = $diff"

19. 1919
Basic TclBasic Tcl
# Variables:# Variables:
setset x 10x 10
setset xx
putsputs “x is $x”“x is $x”
# Functions and expressions:# Functions and expressions:
setset y [pow x 2]y [pow x 2]
setset y [expr x*x]y [expr x*x]
# Control flow:# Control flow:
ifif {$x > 0} {{$x > 0} { returnreturn $x }$x } elseelse {{
returnreturn [expr -$x] }[expr -$x] }
whilewhile { $x > 0 } {{ $x > 0 } {
putsputs $x$x
incrincr x –1x –1
}}
forfor {{setset i 0} {$i<10} {i 0} {$i<10} {incrincr i} {i} {
putsputs “$i == $i”“$i == $i”
}}
# Procedures:# Procedures:
procproc pow {x n} {pow {x n} {
ifif {$n == 1} {{$n == 1} { returnreturn $x }$x }
setset part [part [powpow x [x [exprexpr $n-1]]$n-1]]
returnreturn [[exprexpr $x*$part]$x*$part]
}}
# Files:# Files:
setset file [file [open “open “nstrace.txt” w]nstrace.txt” w]
setset line [line [getsgets $file]$file]
puts –nonewlineputs –nonewline $file “hello!”$file “hello!”
closeclose $file$file

20. 2020
Basic OTclBasic OTcl
Class Person
# constructor:
Person instproc init {age} {
$self instvar age_
set age_ $age
}
# method:
Person instproc greet {} {
$self instvar age_
puts “age $age_: Hello!”
}
# subclass:# subclass:
ClassClass Child -Child -superclasssuperclass
PersonPerson
ChildChild instprocinstproc greet {} {greet {} {
$$selfself instvarinstvar age_age_
putsputs “age $age_ kid:“age $age_ kid:
Wassup!”Wassup!”
}}
setset a [a [newnew Person 45]Person 45]
setset b [b [newnew Child 15]Child 15]
$a greet$a greet
$b greet$b greet

21. What NS2 Can SimulateWhat NS2 Can Simulate
 •• Wired networkWired network
 Traffic model and applicationsTraffic model and applications
 Transport protocolTransport protocol
 Routing and QueuingRouting and Queuing
 QoSQoS
 LANsLANs
 •• Wireless networkWireless network
 Ad hoc routing and mobile IPAd hoc routing and mobile IP
 Sensor networkSensor network
 Propagation model/Energy modelPropagation model/Energy model
 WLAN (802.11)WLAN (802.11)
 •• SatelliteSatellite
 •• Error modulesError modules
 •• Tracing, visualization, emulation, variousTracing, visualization, emulation, various

22. NS2 Supported Protocols(Wired)NS2 Supported Protocols(Wired)
•• ApplicationApplication
HTTP, web cachingHTTP, web caching
telnet, FTP, RealAudiotelnet, FTP, RealAudio
CBR, on-off sourceCBR, on-off source
•• TransportTransport
UDP, TCP (almost all variants of TCP), RTPUDP, TCP (almost all variants of TCP), RTP
SRM, PLM, LMS, PGMSRM, PLM, LMS, PGM
•• RoutingRouting
Unicast (DV, LM, etc) and multicast routing (PIM etc)Unicast (DV, LM, etc) and multicast routing (PIM etc)
Hierarchical routingHierarchical routing
Manual routingManual routing
BroadcastingBroadcasting
MPLSMPLS
•• QueuingQueuing
RED, FIFO, FQ, SFQ, DRR, CBQRED, FIFO, FQ, SFQ, DRR, CBQ
Diffserv and IntServDiffserv and IntServ
ECNECN

23. NS2 Supported Protocols(Wireless)NS2 Supported Protocols(Wireless)
 Ad-hoc network routingAd-hoc network routing
AODV, DSR, TORA, DSDVAODV, DSR, TORA, DSDV
•• Mobile IPMobile IP
•• ARPARP
•• Radio propagation modelRadio propagation model
Friss-space attenuationFriss-space attenuation
Two-ray ground reflection modelTwo-ray ground reflection model
Shadowing modelShadowing model
•• Sensor networkSensor network
Direct diffusionDirect diffusion
SMACSMAC
•• WLANWLAN
Ad-hoc modeAd-hoc mode
Infrastructure modeInfrastructure mode
•• SatelliteSatellite
GeostationaryGeostationary
LEOLEO
• Energy model

24. InstallationInstallation
This Work is available at explanationThis Work is available at explanation
timetime

25. ©Arshad Khan©Arshad Khan 2525
NS-2 Directory Structure
sim
tk8.0 otcl Tcltcl8.0 ns-2 nam-1
tcl
ex test lib
...
...
tcl code
example
validation test
C++ code
tcl code core

26. ArchitectureArchitecture
 LanguagesLanguages
 Internal StructureInternal Structure
 Architecture (User view)Architecture (User view)

27. 2727
App1
Agent1
App2
Agent2
Node
From Network to SimulationFrom Network to Simulation
Application,
Agent &
Node
Lin
k
Node
App1
Agent1
App2
Agent2
Node
App1
Agent1
App2
Agent2
Node
App1
Agent1
App2
Agent2
Node
Node Node Node
Link
Link
Link Link
Link
Link
Link
Link
App1
Agent1
App2
Agent2
Node
App1
Agent1
App2
Agent2
Node
puts "$a + $b = $sum"

28. 2828
Class Hierarchy (partial)Class Hierarchy (partial)
TclObject
NsObject
Connector Classifier
Queue Delay Agent Trace
Enq Deq Drop
AddressClassifier
TCP
SACKReno
DropTail REDTable of n slots each pointing to a TclObject
classify() identifies destination slot for packet
AddressClassifier, PortClassifier found within Nodes
Receive packets and transmit to target_
Basis for Agents and Links (~Queue + Delay)

29. Arshad KhanArshad Khan 2929
What is NS2?What is NS2?
 Network SimulatorNetwork Simulator
 A package of tools that simulatesA package of tools that simulates
behavior of networksbehavior of networks
• Create Network TopologiesCreate Network Topologies
• Log events that happen under any loadLog events that happen under any load
• Analyze events to understand theAnalyze events to understand the
network behaviornetwork behavior

30. Arshad KhanArshad Khan 3030
Creating TopologiesCreating Topologies
n1
n4
n2
n5
n6
n3
5Mbps,
10ms
2Mbps,
20ms
300Kbps,
100ms
300Kbps,
100ms
500Kbps,
50ms

31. Arshad KhanArshad Khan 3131
Creating TopologiesCreating Topologies
 NodesNodes
• Set properties like queue length,Set properties like queue length,
locationlocation
• Protocols, routing algorithmsProtocols, routing algorithms
 LinksLinks
• Set types of link – Simplex, duplex,Set types of link – Simplex, duplex,
wireless, satellitewireless, satellite
• Set bandwidth, latency etc.Set bandwidth, latency etc.
 Done through tcl ScriptsDone through tcl Scripts

32. Arshad KhanArshad Khan 3232
Observing Network BehaviorObserving Network Behavior
 Observe behavior by tracing “events”Observe behavior by tracing “events”
• Eg. packet received, packet drop etc.Eg. packet received, packet drop etc.
time
Src Dst IP
Address, Port

33. Step2: TracingStep2: Tracing

34. Basic Simulation StepsBasic Simulation Steps
1.1. Creating Simulation ObjectCreating Simulation Object
2.2. Opening a file for network animatorOpening a file for network animator
3.3. Finish ProcedureFinish Procedure
4.4. Execution Time for SimulationExecution Time for Simulation
Procedure (Calling finish Procedure)Procedure (Calling finish Procedure)
5.5. Start The SimulationStart The Simulation

35. Basic Simulation StepsBasic Simulation Steps
Creating Simulation ObjectCreating Simulation Object
CommandCommand
*set ns [new Simulator]**set ns [new Simulator]*
1.1. Set ns -Set ns -Declare The New Variable NameDeclare The New Variable Name nsns UsingUsing
TheThe setset Command.Command.
2.2. [new Simulator]-[new Simulator]-is indeed The Instantiation ofis indeed The Instantiation of
The ClassThe Class SimulatorSimulator Using The KeywordUsing The Keyword newnew
3.3. SoSo nsns is Theis The SimulatorSimulator ObjectObject
4.4. Now UsingNow Using nsns Variable We Can Access All TheVariable We Can Access All The
Methods of ClassMethods of Class SimulatorSimulator

36. Basic Simulation StepsBasic Simulation Steps
Opening a File for Network AnimatorOpening a File for Network Animator
or (Opening a NAM Trace File)or (Opening a NAM Trace File)
CommandCommand
** set tracefile1 [open out.nam w]set tracefile1 [open out.nam w]
$ns namtrace-all $tracefile1 *$ns namtrace-all $tracefile1 *
1.1. Open a Trace fileOpen a Trace file out.namout.nam for writng and give itfor writng and give it
to file handlerto file handler tracefile1tracefile1..
2.2. We Are Telling Simulator ObjectWe Are Telling Simulator Object nsns To We HaveTo We Have
Created a file To Write all The Data Related toCreated a file To Write all The Data Related to
Network animator on That FileNetwork animator on That File
3.3. With in a TCL Script file is not called by itsWith in a TCL Script file is not called by its
name(name(out.namout.nam) but Using Pointer () but Using Pointer ( tracefile1tracefile1 ) .) .

37. Cont….Cont….
 namtrace-all-namtrace-all-It is aIt is a SimulatorSimulator
method which takes the parametermethod which takes the parameter
as file name (as file name (tracefile1tracefile1)where trace)where trace
will go.will go.

38. Basic Simulation StepsBasic Simulation Steps
Finish ProcedureFinish Procedure
CODECODE
proc finish {} {proc finish {} {
global ns tracefile1global ns tracefile1
$ns flush-trace$ns flush-trace
close $tracefile1close $tracefile1
exec nam out.nam &exec nam out.nam &
exit 0exit 0
}}

39. CONT…CONT…
 proc finish {}-proc finish {}- The wordThe word procproc declares adeclares a
procedure nameprocedure name finishfinish without anywithout any
argumentsarguments
 global ns tracefile1-global ns tracefile1- The word global isThe word global is
used to tell we are using the variableused to tell we are using the variable
which has declared outside the procedurewhich has declared outside the procedure
((finishfinish) i.e.,) i.e.,ns, tracefile1ns, tracefile1
 $ns flush-trace-$ns flush-trace- flush-traceflush-trace is ais a SimulatorSimulator
method which is used to dump the tracesmethod which is used to dump the traces
on the respective files.on the respective files.

40. Cont..Cont..
 close $tracefile1-close $tracefile1- which close thewhich close the
tracefile1tracefile1
 exec nam out.nam &-exec nam out.nam &- exeexe exicuteexicute
thethe namnam for visualationfor visualation
 exit 0-exit 0- normal termination ofnormal termination of
procedureprocedure

41. Basic Simulation StepsBasic Simulation Steps
Execution Time for Simulation ProcedureExecution Time for Simulation Procedure
(Calling finish Procedure)(Calling finish Procedure)
CommandCommand
*$ns at 5.0 "finish“**$ns at 5.0 "finish“*
 We are telling the simulator object (We are telling the simulator object (nsns) to) to
execute theexecute the finishfinish procedure after 5procedure after 5
second ofsecond of simulationsimulation timetime

42. Basic Simulation StepsBasic Simulation Steps
Start the simulationStart the simulation
CommandCommand
*$ns run**$ns run*
Which is start the simulationWhich is start the simulation

43. Simplified SceniroSimplified Sceniro

44. Creating Nodes & LinksCreating Nodes & Links
1.1. Creating NodesCreating Nodes
2.2. Creating LinksCreating Links

45. Creating NodesCreating Nodes
CommandCommand
*set n0 [$ns node]*set n0 [$ns node]
set n1 [$ns node]*set n1 [$ns node]*
 A new node object is created withA new node object is created with
the commandthe command '$ns node''$ns node'..
 The above code creates two nodesThe above code creates two nodes
and assigns them to the handlesand assigns them to the handles 'n0''n0'
andand 'n1''n1'..

46. 4646
Ns Node
n0 n1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
0
1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
1
0
set n0 [$ns node]
set n1 [$ns node]

47. Creating LinksCreating Links
CommandCommand
*$ns duplex-link $n0 $n1 1Mb 10ms*$ns duplex-link $n0 $n1 1Mb 10ms
Drop Tail*Drop Tail*
 Code tells the simulator object toCode tells the simulator object to
connect the nodesconnect the nodes n0n0 andand n1n1 with awith a
duplex linkduplex link with thewith the bandwidthbandwidth
1Megabit1Megabit, a, a delay of 10msdelay of 10ms and aand a
Drop Tail queue.Drop Tail queue.

48. 4848
Network Topology - Link
n0 n1
enqT_ queue_ deqT_
drophead_ drpT_
link_ ttl_
n1
entry_head_
$ns duplex-link $n0 $n1 1Mb 10ms DropTail

49. 4949
Routing
n0 n1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
0
1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
1
0
Link n0-
n1
Link n1-
n0

50. Creating AgentsCreating Agents
In ns, data is always being sent fromIn ns, data is always being sent from
one 'agent' to anotherone 'agent' to another
1.1. UDPUDP
2.2. CBRCBR
3.3. TCPTCP
4.4. NULLNULL
5.5. Connecting AgentsConnecting Agents
6.6. Schedule The CBRSchedule The CBR

51. UDP AgentUDP Agent
CommandCommand
*set udp0 [new Agent/UDP]*set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0*$ns attach-agent $n0 $udp0*
 These lines create aThese lines create a UDP agentUDP agent
(udp0)(udp0)
 Attach Agent (Attach Agent (udp0udp0)to the node)to the node n0n0

52. TCP AgentTCP Agent
CommandCommand
*set tcp0 [new Agent/UDP]*set tcp0 [new Agent/UDP]
$ns attach-agent $n0 $tcp0*$ns attach-agent $n0 $tcp0*
 These lines create aThese lines create a TCP agentTCP agent
(tcp0)(tcp0)
 Attach Agent (Attach Agent (tcp0tcp0)to the node)to the node n0n0

53. 5353
0
1
Transport
n0 n1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
0 Agent/TCP
agents_
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
1
0
Link n0-
n1
Link n1-
n0
0 Agent/TCPSink
agents_
dst_=1.0 dst_=0.0
set tcp [new Agent/TCP]
$ns attach-agent $n0 $tcp

54. CBR AgentCBR Agent
CommandCommand
*set cbr0 [new Application/Traffic/CBR]*set cbr0 [new Application/Traffic/CBR]
$cbr0 set packet Size_ 500$cbr0 set packet Size_ 500
$cbr0 set interval_ 0.005*$cbr0 set interval_ 0.005*
 CBRCBR stands for 'constant bit ratestands for 'constant bit rate
 First line create theFirst line create the CBRCBR Agent (Agent (cbr0cbr0))
 The packet Size is being set to 500 bytesThe packet Size is being set to 500 bytes
 packet will be sent every 0.005 secondspacket will be sent every 0.005 seconds

55. NULL AgentNULL Agent
CommandCommand
*set null0 [new Agent/Null]*set null0 [new Agent/Null]
$ns attach-agent $n1 $null0*$ns attach-agent $n1 $null0*
 These line Creates a Null AgentThese line Creates a Null Agent
(null0)(null0) Which act as a traffic sink.Which act as a traffic sink.
 Attach AgentAttach Agent (null0)(null0) to the nodeto the node n1n1

56. TCP Sink AgentTCP Sink Agent
CommandCommand
set sink0 [new Agent/TCPSink]set sink0 [new Agent/TCPSink]
$ns attach-agent $n0 $sink0$ns attach-agent $n0 $sink0
 These lines creates aThese lines creates a TCPSinkTCPSink
Agent(sink0)Agent(sink0)
 Attach agentAttach agent (sink0)(sink0) to the nodeto the node n0n0

57. Connect The AgentsConnect The Agents
Connect The Two Agents UDP & NULLConnect The Two Agents UDP & NULL
CommandCommand
*$ns connect $udp0 $null0**$ns connect $udp0 $null0*
 Which is used to connect the twoWhich is used to connect the two
agentsagents udp0udp0 andand null0null0..

58. Connect The AgentsConnect The Agents
Connect The Two Agents TCP &TCP SINKConnect The Two Agents TCP &TCP SINK
CommandCommand
*$ns connect $tcp0 $sink0**$ns connect $tcp0 $sink0*
 Which is used to connect the twoWhich is used to connect the two
agentsagents tcp0tcp0 andand sink0sink0..

59. 5959
Application
0
1
n0 n1
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
0 Agent/TCP
agents_
Addr
Classifier
Port
Classifier
classifier_
dmux_
entry_
1
0
Link n0-
n1
Link n1-
n0
0 Agent/TCPSink
agents_
dst_=1.0 dst_=0.0
Application/FTP
set ftp [new Application/FTP]
$tcp attach-agent $ftp

60. Schedule The CBRSchedule The CBR
To tell CBR to When to start & stopTo tell CBR to When to start & stop
the data sendingthe data sending
CommandCommand
$ns at 0.5 "$cbr0 start“$ns at 0.5 "$cbr0 start“
$ns at 4.5 "$cbr0 stop“$ns at 4.5 "$cbr0 stop“
 AfterAfter 55 simulation secondssimulation seconds cbr0cbr0 startstart
the sending packet and afterthe sending packet and after 4.54.5m itm it
stopstop

61. 6161
Packet Flow
0
1
n0 n1
Addr
Classifier
Port
Classifier
entry_
0 Agent/TCP Addr
Classifier
Port
Classifier
entry_
1
0
Link n0-
n1
Link n1-
n0
0 Agent/TCPSink
dst_=1.0 dst_=0.0
Application/FTP

62. Wired Example ProgramWired Example Program
(UDP Communication)(UDP Communication)
 Two NodesTwo Nodes
 One LinkOne Link
 UDP CommunicationUDP Communication
 BandwidthBandwidth
 DelayDelay
 Drop tail QueueDrop tail Queue

63. Arshad KhanArshad Khan 6363
A simple Example – Creating the topologyA simple Example – Creating the topology
n1 n2
Bandwidth:1Mbps
Latency: 10ms

64. Arshad KhanArshad Khan 6464
Adding trafficAdding traffic
n1 n2
1Mbps,10ms
udp
null
cbr
Packet Size: 500
bytes
rate: 800Kbps
cbr traffic
0.0
0.5
5.0
4.5 time
node
agent
source
link

65. All at One GlanceAll at One Glance
1.1. Create Simulator ObjectCreate Simulator Object
2.2. Open a Network Animator FileOpen a Network Animator File
3.3. Finish ProcedureFinish Procedure
4.4. Create a NodesCreate a Nodes
5.5. Create a LinkCreate a Link
6.6. Create & Attach UDP agent at One NodeCreate & Attach UDP agent at One Node
7.7. Create & Attach CBR agent to UDP AgentCreate & Attach CBR agent to UDP Agent
8.8. Attach NULL agent To another NodeAttach NULL agent To another Node
9.9. Connect The Agents ( UDP & NULL)Connect The Agents ( UDP & NULL)
10.10. Schedule The Start and Stop Time To CBR AgentSchedule The Start and Stop Time To CBR Agent
11.11. Call the Finish procedure (Schedule the Simulation)Call the Finish procedure (Schedule the Simulation)
12.12. Run The SimulationRun The Simulation

66. Wired Example ProgramWired Example Program
(TCP Communication)(TCP Communication)
 Two nodesTwo nodes
 One linkOne link
 TCP CommunicationTCP Communication
 BandwidthBandwidth
 DelayDelay
 Drop tail QueueDrop tail Queue

67. All at One GlanceAll at One Glance
1.1. Create Simulator ObjectCreate Simulator Object
2.2. Open a Network Animator FileOpen a Network Animator File
3.3. Finish ProcedureFinish Procedure
4.4. Create a NodesCreate a Nodes
5.5. Create a LinkCreate a Link
6.6. Create & Attach TCP agent at One NodeCreate & Attach TCP agent at One Node
7.7. Create & Attach CBR agent to TCP AgentCreate & Attach CBR agent to TCP Agent
8.8. Attach TCPSINK agent To another NodeAttach TCPSINK agent To another Node
9.9. Connect The Agents ( TCP & TCPSINK)Connect The Agents ( TCP & TCPSINK)
10.10. Schedule The Start and Stop Time To CBR AgentSchedule The Start and Stop Time To CBR Agent
11.11. Call the Finish procedure (Schedule the Simulation)Call the Finish procedure (Schedule the Simulation)
12.12. Run The SimulationRun The Simulation

68. Wired Example ProgramWired Example Program
(TCP Communication)(TCP Communication)
 Two nodesTwo nodes
 One linkOne link
 TCP CommunicationTCP Communication
 BandwidthBandwidth
 DelayDelay
 Drop tail QueueDrop tail Queue

69. Example : TCPExample : TCP
set ns [new Simulator]
set n0 [$ns node]
set n1 [$ns node]
n0 n1
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ns at 0.2 "$ftp start"
$ns at 1.2 ”exit"
$ns run
$ns duplex-link $n0 $n1 1.5Mb
10ms DropTail
set tcp [new Agent/TCP]
set tcpsink [new
Agent/TCPSink]
$ns attach-agent $n0 $tcp
$ns attach-agent $n1 $tcpsink
$ns connect $tcp $tcpsink

70. Script to startScript to start namnam
set nf [open out.nam w]set nf [open out.nam w]
$ns namtrace-all $nf$ns namtrace-all $nf
proc finish {} {proc finish {} {
global ns nfglobal ns nf
$ns flush-trace$ns flush-trace
close $nfclose $nf
exec nam out.nam &exec nam out.nam &
exit 0exit 0
}}
# your code goes in here# your code goes in here
$ns at 12.0 "finish" # 12.0 is the simulation time in secs$ns at 12.0 "finish" # 12.0 is the simulation time in secs

71. 7171
Script CodeScript Code
# Create a topology# Create a topology
Set ns [new Simulator]Set ns [new Simulator]
set n0 [$ns node]set n0 [$ns node]
set n1 [$ns node]set n1 [$ns node]
$ns duplex-link $n0 $n1 1Mb 10ms DropTail$ns duplex-link $n0 $n1 1Mb 10ms DropTail
# Add Transport agents# Add Transport agents
set tcp [new Agent/TCP]set tcp [new Agent/TCP]
$ns attach-agent $n0 $tcp$ns attach-agent $n0 $tcp
set tcpsink [new Agent/TCPSink]set tcpsink [new Agent/TCPSink]
$ns attach-agent $n1 $tcpsink$ns attach-agent $n1 $tcpsink
$tcp connect $tcpsink$tcp connect $tcpsink
# Add application# Add application
set ftp [new Application/FTP]set ftp [new Application/FTP]
$ftp attach-agent $tcp$ftp attach-agent $tcp
# Create a schedule
$ns at 0.5 "$ftp start"
$ns at 4.5 "$ftp stop"
#Run the simulation
$ns run
n0 n1
1Mb
10ms
FTP
TCP
FTP
TCP

72. 7272
Discrete Event-Driven
Simulator
time_, uid_, next_, handler_
head_ ->
handler_ -> handle()
time_, uid_, next_, handler_insert
$ns at 0.5 “$ftp start”
$ns at 4.5 “$ftp stop”
$ns run

73. Packets Dropping from linkPackets Dropping from link

74. Cont…Cont…
 Create 4 nodes with 3 links.Create 4 nodes with 3 links.
 Bandwidth 1mbps & Delay 10ms.Bandwidth 1mbps & Delay 10ms.
 UDP Agent at node n0,n1.UDP Agent at node n0,n1.
 NULL Agent at node n3.NULL Agent at node n3.

75. Thank you for your patientThank you for your patient