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Friday, October 29, 2010

STUDY OF ALOHA PROTOCOL USING NS2 NETWORK JAVA PRORAM

Program:

#Create a simulator object

set ns [new Simulator]



#Tell the simulator to use dynamic routing

$ns rtproto DV

$ns macType Mac/Sat/UnslottedAloha



#Open the nam trace file

set nf [open aloha.nam w]

$ns namtrace-all $nf



#Open the output files

set f0 [open aloha.tr w]

$ns trace-all $f0



#Define a 'finish' procedure

proc finish {} {

global ns f0 nf

$ns flush-trace

#Close the trace file

close $f0

close $nf

#Call xgraph to display the results

exec nam aloha.nam &

exit 0 }


# Create six nodes

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]

set n5 [$ns node]



# Create duplex links between nodes with bandwidth and distance

$ns duplex-link $n0 $n4 1Mb 50ms DropTail

$ns duplex-link $n1 $n4 1Mb 50ms DropTail

$ns duplex-link $n2 $n5 1Mb 1ms DropTail

$ns duplex-link $n3 $n5 1Mb 1ms DropTail

$ns duplex-link $n4 $n5 1Mb 50ms DropTail

$ns duplex-link $n2 $n3 1Mb 50ms DropTail



# Create a duplex link between nodes 4 and 5 as queue position

$ns duplex-link-op $n4 $n5 queuePos 0.5



#Create a UDP agent and attach it to node n(0)

set udp0 [new Agent/UDP]

$ns attach-agent $n0 $udp0



# Create a CBR traffic source and attach it to udp0

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 500

$cbr0 set interval_ 0.005

$cbr0 attach-agent $udp0



#Create a Null agent (a traffic sink) and attach it to node n(3)

set null0 [new Agent/Null]

$ns attach-agent $n2 $null0



#Connect the traffic source with the traffic sink

$ns connect $udp0 $null0



#Schedule events for the CBR agent and the network dynamics

$ns at 0.5 "$cbr0 start"

$ns rtmodel-at 1.0 down $n5 $n2

$ns rtmodel-at 2.0 up $n5 $n2

$ns at 4.5 "$cbr0 stop"



#Call the finish procedure after 5 seconds of simulation time

$ns at 5.0 "finish"



#Run the simulation

$ns run

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