# инициализация NS2
set ns [new Simulator]
set nf [open out.nam w]
$ns namtrace-all $nf
set f [open out.tr w]
$ns trace-all $f

proc finish {} {
  global ns f nf
  $ns flush-trace
  close $f
  close $nf

  exec nam out.nam &
  exit 0
}
#=======================
set N 4
set red_node [$ns node]
set target_node [$ns node]
for {set i 0} {$i < $N } {incr i} {
    set n($i) [$ns node]
}
#=======================
$ns duplex-link $red_node $target_node $N\\Mb 20ms RED
$ns queue-limit $red_node $target_node [expr $N * 10 ]
#=======================
for {set i 0} {$i < $N } {incr i} {
    $ns duplex-link $n($i) $red_node 1Mb 10ms DropTail
}
#=======================
set sink [new Agent/TCPSink]
$ns attach-agent $target_node $sink
set null [new Agent/Null]
$ns attach-agent $target_node $null
#=======================
set udp [$ns create-connection UDP $n(0) Null $target_node 0]
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set packetSize_ 1024
$cbr set rate_ 1Mbps
#=======================
for {set i 1} {$i < $N} {incr i} {
    set tcp($i) [$ns create-connection TCP/Reno $n($i) TCPSink $target_node 0]
    set ftp($i) [$tcp($i) attach-source FTP]
}
#=======================
for {set i 1} {$i < $N} {incr i} {
    $ns at 0.0 "$ftp($i) start"
}
$ns at 0.0 "$cbr start"
$ns at 5.0 "finish"
$ns run