# Creating event scheduler
set ns [new Simulator]

# make it easy to put output in different files
set outprefix out

# setup traces
$ns trace-all [open $outprefix.tr w]
set nf [open $outprefix.nam w]
$ns namtrace-all $nf
# turn on extra tcp tracing for nam
Agent/TCP set nam_tracevar_ true

# Create the topology
#
# n0 --- n1  --- n2 --- n3
#
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

# Creating the links
# All with bandwidth 10Mb, delay 10ms, and DropTail queue
# Except the bottleneck link with bw 1Mb, delay 30ms, and DropTail queue
$ns duplex-link $n0 $n1 10Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 30ms DropTail
$ns duplex-link $n2 $n3 10Mb 10ms DropTail

#
# tell nam how to arrange the nodes
#
$ns duplex-link-op $n0 $n1 orient left-up
$ns duplex-link-op $n1 $n2 orient left
$ns duplex-link-op $n2 $n3 orient left-down

# Create a TCP Reno connection from node 0 to node 3
# with a sink that will ack every packet
set tcpsrc [new Agent/TCP/Reno]
set tcpsnk [new Agent/TCPSink]
$ns attach-agent $n0 $tcpsrc
$ns attach-agent $n3 $tcpsnk
$ns connect $tcpsrc $tcpsnk

# Create an FTP source, attach it to the TCP agent
set ftp [new Application/FTP]
$ftp attach-agent $tcpsrc

#
# create and add an error model
#
set em [new ErrorModel/List]
# drop a particular packet (packets are numbered from 0)
$em droplist {100}
$ns lossmodel $em $n1 $n2

# schedule the ftp source to send some data starting at a specific time.
$ns at 1.0 "$ftp produce 8"

$ns at 15.0 "finish"

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

	puts "Filtering ..."
	exec tclsh ~csci551/ns-allinone-2.1b8a/nam/bin/namfilter.tcl $outprefix.nam
	puts "running nam..."
	exec ~csci551/ns-allinone-2.1b8a/nam/nam $outprefix.nam &
	exit 0
}
$ns run