#Create a simulator object
set ns [new Simulator]

#Define different colors for data flows
$ns color 1 Blue
$ns color 2 Red

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

#Define a ‘finish’ procedure
proc finish {} {
global ns nf
$ns flush-trace
#Close the trace file
close $nf
#Execute nam on the trace file
exec nam out.nam &
exit 0
}

#Create four nodes
#for {set i 1}{i<= 4}{incr i}{
#set n($i) [$ns node]
#}
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 links between the nodes
$ns duplex-link $n0 $n2 1Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 10ms DropTail
$ns duplex-link $n3 $n2 1Mb 10ms SFQ
$ns duplex-link $n3 $n4 1Mb 10ms DropTail
$ns duplex-link $n3 $n5 1Mb 10ms DropTail

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

#Monitor the queue for the link between node 2 and node 3
$ns duplex-link-op $n2 $n3 queuePos 0.5

#Create a UDP agent and attach it to node n0
set udp0 [new Agent/UDP]
$udp0 set class_ 1
$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 n3
set null0 [new Agent/Null]
$ns attach-agent $n5 $null0

#Connect the traffic sources with the traffic sink
$ns connect $udp0 $null0

#Create a TCP agent and attach it to node n1
set tcp0 [new Agent/TCP]
$tcp0 set class_ 2
$ns attach-agent $n1 $tcp0

# Create a FTP traffic source and attach it to tcp0
set ftp0 [new Application/FTP]
$ftp0 set type_ FTP
$ftp0 attach-agent $tcp0

#Create a TCPSink (a traffic sink) and attach it to node n3
set null1 [new Agent/TCPSink]
$ns attach-agent $n4 $null1

#Connect the traffic sources with the traffic sink
$ns connect $tcp0 $null1

#Schedule events for the CBR agents
$ns at 0.5 “$cbr0 start”
$ns at 1.0 “$ftp0 start”
$ns at 4.0 “$ftp0 stop”
$ns at 4.5 “$cbr0 stop”
#Call the finish procedure after 5 seconds of simulation time
$ns at 5.0 “finish”

#Run the simulation
$ns run