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# It will show how TCP adjusts its window size by multiplicative decrease
# features : labeling, annotation, nam-graph, and window size monitoring
#
# n0 --- n1 -------------- n2 --- n3
#
set ns [new Simulator]
$ns trace-all [open D1-m-decrease.tr w]
$ns namtrace-all [open D1-m-decrease.nam w]
### build topology with 4 nodes
foreach i " 0 1 2 3 " {
set n$i [$ns node]
}
$ns at 0.0 "$n0 label TCP"
$ns at 0.0 "$n3 label TCP"
$ns duplex-link $n0 $n1 5Mb 20ms DropTail
$ns duplex-link $n1 $n2 0.5Mb 100ms DropTail
$ns duplex-link $n2 $n3 5Mb 20ms DropTail
$ns queue-limit $n1 $n2 5
$ns duplex-link-op $n0 $n1 orient right
$ns duplex-link-op $n1 $n2 orient right
$ns duplex-link-op $n2 $n3 orient right
$ns duplex-link-op $n1 $n2 queuePos 0.5
### set TCP variables
Agent/TCP set nam_tracevar_ true
Agent/TCP set window_ 20
Agent/TCP set ssthresh_ 20
### TCP between n0 and n3 (Black)
set tcp [new Agent/TCP]
$ns attach-agent $n0 $tcp
set sink [new Agent/TCPSink]
$ns attach-agent $n3 $sink
$ns connect $tcp $sink
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ns add-agent-trace $tcp tcp
$ns monitor-agent-trace $tcp
$tcp tracevar cwnd_
$tcp tracevar ssthresh_
proc finish {} {
global ns
$ns flush-trace
puts "filtering..."
exec tclsh ../bin/namfilter.tcl D1-m-decrease.nam
puts "running nam..."
exec nam D1-m-decrease.nam &
exit 0
}
### set operations
$ns at 0.1 "$ftp start"
$ns at 5.0 "$ftp stop"
$ns at 5.1 "finish"
### add annotations
$ns at 0.0 "$ns trace-annotate \"TCP with multiplicative decrease\""
$ns run
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