#Exemplo dado em aula pelo professor.
#A documentação do ns2 possui uma boa explicação sobre cada uma das funções utiliza
#das aqui. Comando:
#   $ man ns

# Inicializa Flags
set run_nam 0

#Create a simulator object
set ns [new Simulator]

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

# ALTERADO #1
#Open the nam trace file
#set nf [open out-ex2.nam w]
#$ns namtrace-all $nf
# PARA #1
#Cria arquivos de saida
set f [open out.tr w]
$ns trace-all $f
set nf [open out.nam w]
$ns namtrace-all $nf
# END #1

# ALTERADO #2
#Define a ’finish’ procedure
#proc finish {} {
#   global ns nf
#   $ns flush-trace
#   #Close the trace file
#   close $nf
#   #Execute nam on the trace file
#   exit 0
#}
# PARA #2
#Procedimento de finalizacao
proc finish {} {
    global ns nf f run_nam
    $ns flush-trace
    close $nf
    close $f

    if {$run_nam} {
      puts "running nam..."
      exec nam out.nam
    }
    exit 0
}
# END #2

#Create four nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$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
#'op' define uma operacao para o link, que no caso é uma definição de
#posicionamento dele.
$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

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

#Create a CBR agent and attach it to node n0
set cbr0 [new Agent/CBR]
$ns attach-agent $n0 $cbr0
$cbr0 set packetSize_ 500
$cbr0 set interval_ 0.005
$cbr0 set fid_ 1

#Create a CBR agent and attach it to node n1
set cbr1 [new Agent/CBR]
$ns attach-agent $n1 $cbr1
$cbr1 set packetSize_ 500
$cbr1 set interval_ 0.005
$cbr1 set fid_ 2

#Create a Null agent (a traffic sink) and attach it to node n3
set null0 [new Agent/Null]
$ns attach-agent $n3 $null0

#Connect the traffic sources with the traffic sink
$ns connect $cbr0 $null0
$ns connect $cbr1 $null0

#Schedule events for the CBR agents
$ns at 0.5 "$cbr0 start"
$ns at 1.0 "$cbr1 start"
$ns at 4.0 "$cbr1 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