#Create a simulator object
set ns [new Simulator]

# tcp   0
#	 \
#	  \
#	   2------------3
#	  /
#	 /
#  cbr  1

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

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

#Open the Trace file
set tf [open out.tr w]
set windowVsTime2 [open WindowVsTimeNReno w]
$ns trace-all $tf

#Define a 'finish' procedure
proc finish {} {
        global ns nf tf
        $ns flush-trace
        close $nf
        close $tf
        exec nam out.nam &
        exit 0
}

#Create four nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

$ns at 0.1 "$n1 label \"CBR\""
$ns at 1.0 "$n0 label \"FTP\""

#Create links between the nodes
$ns duplex-link $n0 $n2 2Mb 10ms DropTail
$ns duplex-link $n1 $n2 2Mb 10ms DropTail
$ns simplex-link $n2 $n3 0.07Mb 20ms DropTail
$ns simplex-link $n3 $n2 0.07Mb 20ms DropTail

#Set Queue Size of link (n2-n3) to 10
$ns queue-limit $n2 $n3 10

#Monitor the queue for link (n2-n3). (for NAM)
$ns simplex-link-op $n2 $n3 queuePos 0.5

#Set error model on link n2 to n3.
set loss_module [new ErrorModel]
$loss_module set rate_ 0.2
$loss_module ranvar [new RandomVariable/Uniform]
$loss_module drop-target [new Agent/Null]
$ns lossmodel $loss_module $n2 $n3

#Setup a TCP connection
set tcp [new Agent/TCP/Newreno]
$ns attach-agent $n0 $tcp
set sink [new Agent/TCPSink/DelAck]
$ns attach-agent $n3 $sink
$ns connect $tcp $sink
$tcp set fid_ 1

#Setup a FTP over TCP connection
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ftp set type_ FTP

#Setup a UDP connection
set udp [new Agent/UDP]
$ns attach-agent $n1 $udp
set null [new Agent/Null]
$ns attach-agent $n3 $null
$ns connect $udp $null
$udp set fid_ 2

#Setup a CBR over UDP connection
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set type_ CBR
$cbr set packet_size_ 1000
$cbr set rate_ 0.01mb
$cbr set random_ false

#Schedule events for the CBR and FTP agents
$ns at 0.1 "$cbr start"
$ns at 1.0 "$ftp start"
$ns at 624.0 "$ftp stop"
$ns at 624.5 "$cbr stop"

# Printing the window size
proc plotWindow {tcpSource file} {
global ns
set time 0.01
set now [$ns now]
set cwnd [$tcpSource set cwnd_]
puts $file "$now $cwnd"
$ns at [expr $now+$time] "plotWindow $tcpSource $file" }
$ns at 1.1 "plotWindow $tcp $windowVsTime2"    

# sample the bottleneck queue every 0.1 sec. store the trace in qm.out
set qmon [$ns monitor-queue $n2 $n3 [open qm.out w] 0.1];
[$ns link $n2 $n3] queue-sample-timeout; # [$ns link $n2 $n3] start-tracing

#Detach tcp and sink agents (not really necessary)
$ns at 624.5 "$ns detach-agent $n0 $tcp ; $ns detach-agent $n3 $sink"

$ns at 625.0 "finish"
$ns run