#
# test_a.tcl
# $xIdx: test_b.tcl,v 1.2 2002/04/20 04:26:06 johnh Exp $
#

proc usage {} {
	puts "Identify the PRIMARY reason limiting the bandwidth of"
	puts "the tcp connection between nodes Left and Right."
}



#
# create the topology
#
proc make_topology {} {
	global ns
	global node_left node_right

	# nodes
	set node_left [$ns node]
	set node_b1 [$ns node]
	set node_b2 [$ns node]
	set node_right [$ns node]

	# links
	$ns duplex-link $node_left $node_b1 2Mbps 10ms DropTail
	$ns duplex-link $node_b1 $node_b2 1Mbps 40ms DropTail
	$ns duplex-link $node_b2 $node_right 2Mbps 10ms DropTail

	# nam hacking
	$node_left shape hexagon
	$node_left label Left
	$node_right shape hexagon
	$node_right label Right
	# orient the nodes relative to each other
	#
	# 19-Apr-02: don't do this currently because of a bug in nam
	# that breaks with absolute positioning :-(
	#
	# $ns duplex-link-op $node_left $node_b1 orient right
	# $ns duplex-link-op $node_b1 $node_b2 orient right
	# $ns duplex-link-op $node_b2 $node_right orient right
}

#
# create the traffic
#
proc make_traffic {} {
	global ns
	global node_left node_right

	# make the source
	set tcp_left [new Agent/TCP/Reno]
	$ns attach-agent $node_left $tcp_left
	# set its flow id
	$tcp_left set fid_ 1

	# sink
	set tcp_sink_right [new Agent/TCPSink]
	$ns attach-agent $node_right $tcp_sink_right

	# hook the source and sink
	$ns connect $tcp_left $tcp_sink_right

	# app over the source
	set ftp_left [new Application/FTP]
	$ftp_left attach-agent $tcp_left
	# start the traffic (send 200 pkts)
	$ns at 1 "$ftp_left produce 200"
	$ns at 10 "$ftp_left stop"
}


#
# set up tracing
#
proc make_tracing {prefix} {
	global ns
	global tr_file nam_file

	set tr_file [open $prefix.tr w]
	$ns trace-all $tr_file

	set nam_file [open $prefix.nam w]
	$ns namtrace-all $nam_file
}

#
# called to end the simulation
#
proc finish {progname} {
	global ns
	global tr_file nam_file

	$ns flush-trace
	close  $tr_file
	close  $nam_file

	puts "Done with simulation."
	puts "You may now look at the output trace files $progname.tr and $progname.nam"
	exit 0
}

proc main {} {
	# get the current script name without .tcl
	global argv0 
	regexp -expanded -nocase {^(.*)\.tcl$} $argv0 dummy progname

	usage

	global ns
	set ns [new Simulator]

	make_tracing $progname
	make_topology
	make_traffic

	$ns at 11 "finish $progname"
	$ns run
}

main
exit 0