Solution Lab6 Exercise 1

#Create a simulator object
set ns [new Simulator]

#Define different colors
$ns color 1 Blue
$ns color 2 Red
$ns color 3 Yellow


#Open the nam trace file
set namf [open out.nam w]
$ns namtrace-all $namf

set f1 [open tcp1.tr w]
set f2 [open tcp2.tr w]

#Define a 'finish' procedure
proc finish {} {
    global ns namf f1 f2
    $ns flush-trace
	#Close the trace amd nam files
    close $namf
	close $f1
	close $f2
	#Execute nam on the trace file
    exec nam out.nam &
    # Execute gnuplot to plot the two tracefiles $tcp1.tr and $tcp2.tr

    exec gnuplot throughput.plot &
    exit 0
}

#Create eight 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]
set n6 [$ns node]
set n7 [$ns node]



#Create links between the nodes
$ns duplex-link $n0 $n1 10Mb 10ms DropTail
$ns duplex-link $n1 $n2 2.5Mb 40ms DropTail
$ns duplex-link $n2 $n3 10Mb 10ms DropTail
$ns duplex-link $n2 $n4 2.5Mb 40ms DropTail
$ns duplex-link $n4 $n5 10Mb 10ms DropTail
$ns duplex-link $n4 $n6 2.5Mb 40ms DropTail
$ns duplex-link $n6 $n7 10Mb 10ms DropTail
$ns duplex-link $n6 $n1 2.5Mb 40ms DropTail

$ns duplex-link-op $n0 $n1 orient right
$ns duplex-link-op $n1 $n2 orient up
$ns duplex-link-op $n2 $n3 orient left
$ns duplex-link-op $n2 $n4 orient right
$ns duplex-link-op $n4 $n5 orient right
$ns duplex-link-op $n4 $n6 orient down
$ns duplex-link-op $n6 $n7 orient right
$ns duplex-link-op $n6 $n1 orient left


#Monitor the queue for the link between node 2 and node 4
$ns queue-limit $n2 $n4 10
$ns duplex-link-op $n2 $n4 queuePos 0.5

#Create a TCP agent and attach it to node n0
set tcp1 [new Agent/TCP]
$ns attach-agent $n0 $tcp1

#Sink for traffic at Node n5
set sink1 [new Agent/TCPSink]
$ns attach-agent $n5 $sink1

$ns connect $tcp1 $sink1
$tcp1 set fid_ 1

#Setup a FTP over TCP connection
set ftp1 [new Application/FTP]
$ftp1 attach-agent $tcp1

#Create a TCP agent and attach it to node n3
set tcp2 [new Agent/TCP]
$ns attach-agent $n3 $tcp2

#Sink for traffic at Node n5
set sink2 [new Agent/TCPSink]
$ns attach-agent $n5 $sink2
$ns connect $tcp2 $sink2
$tcp2 set fid_ 2

#Setup a FTP over TCP connection
set ftp2 [new Application/FTP]
$ftp2 attach-agent $tcp2

#Create a TCP agent and attach it to node n7
set tcp3 [new Agent/TCP]
$ns attach-agent $n7 $tcp3

#Sink for traffic at Node n0
set sink3 [new Agent/TCPSink]
$ns attach-agent $n0 $sink3

$ns connect $tcp3 $sink3
$tcp3 set fid_ 3

#Setup a FTP over TCP connection
set ftp3 [new Application/FTP]
$ftp3 attach-agent $tcp3

#Create a TCP agent and attach it to node n7
set tcp4 [new Agent/TCP]
$ns attach-agent $n7 $tcp4

#Sink for traffic at Node n3
set sink4 [new Agent/TCPSink]
$ns attach-agent $n3 $sink4

$ns connect $tcp4 $sink4
$tcp3 set fid_ 4

#Setup a FTP over TCP connection
set ftp4 [new Application/FTP]
$ftp4 attach-agent $tcp4

proc record {} {
        global sink1 sink2 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 0.1
        #How many bytes have been received by the traffic sinks at n5?
        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 $f1 "$now [expr $bw1/$time*8/1000000]"
        puts $f2 "$now [expr $bw2/$time*8/1000000]"
        #Reset the bytes_ values on the traffic sinks
        $sink1 set bytes_ 0
        $sink2 set bytes_ 0
        #Re-schedule the procedure
        $ns at [expr $now+$time] "record"
}


#Schedule events for the CBR agents
$ns at 0.0 "record"
$ns at 0.5 "$ftp1 start"
$ns at 2.0 "$ftp2 start"
$ns at 3.0 "$ftp3 start"
$ns at 4.0 "$ftp4 start"

$ns at 7.0 "$ftp4 stop"
$ns at 8.5 "$ftp1 stop"
$ns at 9.5 "$ftp2 stop"
$ns at 9.5 "$ftp3 stop"


#Call the finish procedure after 10 seconds of simulation time
$ns at 10.0 "finish"

#Run the simulation
$ns run