Hello! First of all I want to thank all the people who help me in my first
post. But now I have another problem with TCP connection. I have two
questions:
1) How can I measure the throughput in a tcp connection?
2) How can I see the evolution of the congestion window when I have 2 TCP
sources connected to the same Sink?
For the second question I made the next simple script:
set ns [new Simulator]
set nf [open out.nam w]
$ns namtrace-all $nf
set f0 [open CWND.tr w]
set f1 [open ssthresh.tr w]
$ns trace-all $f0
$ns trace-all $f1
proc finish {} {
global ns nf f0 f1
$ns flush-trace
close $nf
close $f0
close $f1
exec nam out.nam &
exec xgraph CWND.tr &
exit 0
}
proc record {} {
global ns tcp tcp2 f0 f1
set ns [Simulator instance]
set time 0.05
set cwnd0 [$tcp set cwnd_]
set cwnd1 [$tcp2 set cwnd_]
set now [$ns now]
puts $f0 "$now $cwnd0"
puts $f1 "$now $cwnd1"
$ns at [expr $now+$time] "record"
}
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
$ns duplex-link $n1 $n3 1Mb 10ms DropTail
$ns duplex-link $n2 $n3 1Mb 10ms DropTail
$ns duplex-link $n3 $n4 1Mb 10ms DropTail
$ns duplex-link-op $n3 $n4 queuePos 0.5
set tcp1 [new Agent/TCP]
$ns attach-agent $n1 $tcp1
set sink1 [new Agent/TCPSink]
$ns attach-agent $n4 $sink1
$ns connect $tcp1 $sink1
set ftp1 [new Application/FTP]
$ftp1 attach-agent $tcp1
set tcp2 [$ns create-connection TCP $n2 TCPSink $n4 2]
set ftp2 [new Application/FTP]
$ftp2 attach-agent $tcp2
$ns at 0.5 "$ftp1 start"
$ns at 0.8 "$ftp2 start"
$ns at 10 "$ftp1 stop"
$ns at 11 "$ftp2 stop"
$ns at 15.0 "finish"
$ns run
But when I simulate it, appears a message about a problem with the input
data, and I dont know what is wrong
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