set opt(tr) outset opt(namtr)	"test-lan-1.nam"set opt(seed)	0set opt(stop)	3set opt(node)	8set opt(qsize)	10set opt(bw)	    1Mbset opt(delay)	100msset opt(ll)	    LLset opt(ifq)	  Queue/DropTailset opt(mac)	  Mac/802_3set opt(chan)	  Channelset opt(tcp)	  TCP/Renoset opt(sink)	  TCPSinkset opt(app)	  FTPproc finish {} {	global env nshome pwd	global ns opt	$ns flush-trace	exit 0}proc create-trace {} {	global ns opt  if [file exists $opt(tr)] {    catch "exec rm -f $opt(tr) $opt(tr)-bw [glob $opt(tr).*]"  }  set trfd [open $opt(tr) w]  $ns trace-all $trfd	if {$opt(namtr) != ""} {		$ns namtrace-all [open $opt(namtr) w]	}  return $trfd}proc create-topology {} {	global ns opt	global lan node source node0	set num $opt(node)	for {set i 0} {$i < $num} {incr i} {		set node($i) [$ns node]		lappend nodelist $node($i)	}	set lan [$ns newLan $nodelist $opt(bw) $opt(delay) \			-llType $opt(ll) -ifqType $opt(ifq) \			-macType $opt(mac) -chanType $opt(chan)]	set node0 [$ns node]	$ns duplex-link $node0 $node(0) 1Mb 100ms DropTail	$ns duplex-link-op $node0 $node(0) orient right}## MAIN ##set ns [new Simulator]set trfd [create-trace]create-topologyset tcp0 [$ns create-connection TCP/Reno $node0 TCPSink $node(7) 0]$tcp0 set window_ 15set ftp0 [$tcp0 attach-app FTP]### set operations$ns at 0.0 "$ftp0 start"$ns at $opt(stop) "finish"### take snapshotsforeach i "0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 \1.2 1.5 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8" {		$ns at $i "$ns snapshot"}### take snapshot operations$ns at 2.9 "$ns terminate-nam"$ns run