[ns] Help : Tcp Throughput.

[Don Lee <leehn@eee-fs7.bham.ac.uk>]

Hi,

I'm trying to obtain the throughput of a tcp connection.
I try to use the TraceApp class method to obtain the total bytes received by
the TCPSink.  But everytime I get a value = 0. Could someone point to me what
wrong with my code. I will aslo like to plot a throughput graph, anyone have
sample code???  


Thanks,

Don



   The following is my code :


Class TraceApp -superclass Application

TraceApp instproc init {args} {
	$self set bytes_ 0
	eval $self next $args
}


TraceApp instproc recv {byte} {
	$self instvar bytes_
	set bytes_ [expr $bytes_+$byte]
	return $bytes_
}

set ns [new Simulator]				


set host1 [$ns node]
set host2 [$ns node]

$ns duplex-link $host1 $host2 10Mb 5ms DropTail


set tcp1 [new Agent/TCP]
$tcp1 set packetSize_ 1000

set sink1 [new Agent/TCPSink]
set traceapp [new TraceApp]
$traceapp attach-agent $sink1

$ns attach-agent $host1 $tcp1
$ns attach-agent $host2 $sink1
$ns connect $tcp1 $sink1

set ftp1 [new Application/FTP]
$ftp1 attach-agent $tcp1


$ns at 0.0 "$traceapp start"
$ns at 10.0 "$ftp1 start"
$ns at 60.0 "$ftp1 stop"
$ns at 65.0 "$traceapp stop ; puts \"total = [$traceapp set bytes_]\""
$ns at 70.0 "puts \"NS Existing ... ...\"; $ns halt"


# start ns

puts "starting simulation ... ..."
puts "\creating topology ... ..."
$ns run