ns2 program for calculating bandwidth using xgraph

#Create a simulator object

set ns [new Simulator]



#Open the output files

set f0 [open out0.tr w]

set f1 [open out1.tr w]

set f2 [open out2.tr w]



#Create 5 nodes

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]



#Connect the nodes

$ns duplex-link $n0 $n3 1Mb 100ms DropTail

$ns duplex-link $n1 $n3 1Mb 100ms DropTail

$ns duplex-link $n2 $n3 1Mb 100ms DropTail

$ns duplex-link $n3 $n4 1Mb 100ms DropTail



#Define a 'finish' procedure

proc finish {} {

    global f0 f1 f2

    #Close the output files

    close $f0

    close $f1

    close $f2

    #Call xgraph to display the results

    exec xgraph out0.tr out1.tr out2.tr -geometry 800x400 &

        exit 0

}





#Define a procedure that attaches a UDP agent to a previously created node

#'node' and attaches an Expoo traffic generator to the agent with the

#characteristic values 'size' for packet size 'burst' for burst time,

#'idle' for idle time and 'rate' for burst peak rate. The procedure connects

#the source with the previously defined traffic sink 'sink' and returns the

#source object.

proc attach-expoo-traffic { node sink size burst idle rate } {

    #Get an instance of the simulator

    set ns [Simulator instance]



    #Create a UDP agent and attach it to the node

    set source [new Agent/UDP]

    $ns attach-agent $node $source



    #Create an Expoo traffic agent and set its configuration parameters

    set traffic [new Application/Traffic/Exponential]

    $traffic set packetSize_ $size

    $traffic set burst_time_ $burst

    $traffic set idle_time_ $idle

    $traffic set rate_ $rate

        

        # Attach traffic source to the traffic generator

        $traffic attach-agent $source

    #Connect the source and the sink

    $ns connect $source $sink

    return $traffic

}





#Define a procedure which periodically records the bandwidth received by the

#three traffic sinks sink0/1/2 and writes it to the three files f0/1/2.

proc record {} {

        global sink0 sink1 sink2 f0 f1 f2

    #Get an instance of the simulator

    set ns [Simulator instance]

    #Set the time after which the procedure should be called again

        set time 0.5

    #How many bytes have been received by the traffic sinks?

        set bw0 [$sink0 set bytes_]

        set bw1 [$sink1 set bytes_]

        set bw2 [$sink2 set bytes_]

    #Get the current time

        set now [$ns now]

    #Calculate the bandwidth (in MBit/s) and write it to the files

        puts $f0 "$now [expr $bw0/$time*8/1000000]"

        puts $f1 "$now [expr $bw1/$time*8/1000000]"

        puts $f2 "$now [expr $bw2/$time*8/1000000]"

    #Reset the bytes_ values on the traffic sinks

        $sink0 set bytes_ 0

        $sink1 set bytes_ 0

        $sink2 set bytes_ 0

    #Re-schedule the procedure

        $ns at [expr $now+$time] "record"

}





#Create three traffic sinks and attach them to the node n4

set sink0 [new Agent/LossMonitor]

set sink1 [new Agent/LossMonitor]

set sink2 [new Agent/LossMonitor]

$ns attach-agent $n4 $sink0

$ns attach-agent $n4 $sink1

$ns attach-agent $n4 $sink2



#Create three traffic sources

set source0 [attach-expoo-traffic $n0 $sink0 200 2s 1s 100k]

set source1 [attach-expoo-traffic $n1 $sink1 200 2s 1s 200k]

set source2 [attach-expoo-traffic $n2 $sink2 200 2s 1s 300k]



#Start logging the received bandwidth

$ns at 0.0 "record"

#Start the traffic sources

$ns at 10.0 "$source0 start"

$ns at 10.0 "$source1 start"

$ns at 10.0 "$source2 start"

#Stop the traffic sources

$ns at 50.0 "$source0 stop"

$ns at 50.0 "$source1 stop"

$ns at 50.0 "$source2 stop"

#Call the finish procedure after 60 seconds simulation time

$ns at 60.0 "finish"



#Run the simulation

$ns run