# a simple script with 2 node topology to test working of ARQ/HDLC # (goBackN and selrepeat) over a satellite link# using a single TCP flow# loss model for urban and rural(open) from Lincoln labs paper added  #set val(chan)           Channel/Sat     ;#Channel Typeset val(netif)          Phy/Sat         ;# network interface typeset val(mac)            Mac/Sat         ;# MAC typeset val(ifq)            Queue/DropTail  ;# interface queue typeset val(ll)             LL/Sat/HDLC     ;# link layer type#set val(ll)              LL/Sat        ;# use this if want to simulate LL                                         # with no HDLC# two types of eror models usedset val(err)            UrbanComplexMarkovErrorModel#set val(err)            RuralComplexMarkovErrorModelset val(bw_up)          10Mbset val(bw_down)        10Mbset val(x)		250set val(y)		250set durlistA        "22.0 26.0 2.9 2.7" ; # avg ON/OFF for urban modelset durlistB        "27.0 12.0 0.4 0.4"  ;# for rural modelset BW 10; # in Mb/sset delay 254; # in ms# Set the queue length (in packets)#set qlen [expr round([expr ($BW / 8.0) * $delay * 2])]; # set buffer to pipe size# set sat link bandwidth and delayMac set bandwidth_ 10MbLL set delay_ 125msset val(bdp) [expr 10000/8.0 * 125/100]LL/Sat/HDLC set window_size_ $val(bdp) LL/Sat/HDLC set queue_size_ $val(bdp)LL/Sat/HDLC set timeout_ 0.26# this is set later#LL/Sat/HDLC set max_timeouts_ 5# set selective repeat on; its GoBackN by default#LL/Sat/HDLC set selRepeat_ 1set qlen $val(bdp)puts "queue len = $qlen"set val(ifqlen) $qlenproc start_time {} {return 0; }# proc start_time {} {return [expr ([eval ns-random] / 2147483647.0) * 0.1]}proc UrbanComplexMarkovErrorModel {} {	global durlistA	set errmodel [new ErrorModel/ComplexTwoStateMarkov $durlistA time]		$errmodel drop-target [new Agent/Null] 	return $errmodel}proc RuralComplexMarkovErrorModel {} {	global durlistB	set errmodel [new ErrorModel/ComplexTwoStateMarkov $durlistB time]		$errmodel drop-target [new Agent/Null] 	return $errmodel}proc stop {} {    global ns_ tracefd    $ns_ flush-trace    close $tracefd}proc setup {tcptype queuetype sources qlen duration file seed c_sources delay rate ecn run retries} {	global val traces ns_ tracefd	if {$retries == "NULL"} {		set val(ll) LL/Sat	} else {		set val(ll) LL/Sat/HDLC		LL/Sat/HDLC set max_timeouts_ $retries	}	# Initialize Global Variables	ns-random $seed	set ns_		[new Simulator]	set tracefd     [open simple-hdlc.tr w]	$ns_ trace-all $tracefd	$ns_ eventtrace-all	$ns_ rtproto Static		# Create sat n(0)		# configure node, please note the change below.	$ns_ node-config -satNodeType geo \	    -llType $val(ll) \	    -ifqType $val(ifq) \	    -ifqLen $val(ifqlen) \	    -macType $val(mac) \	    -phyType $val(netif) \	    -channelType $val(chan) \	    -downlinkBW $val(bw_down) \	    -wiredRouting ON	set n(0) [$ns_ node]	$n(0) set-position -95	$ns_ node-config -satNodeType terminal	set n(101) [$ns_ node]	$n(101) set-position 42.3 -71.1; # Boston	$n(101) add-gsl geo $val(ll) $val(ifq) $val(ifqlen) $val(mac) $val(bw_up) \	    $val(netif) [$n(0) set downlink_] [$n(0) set uplink_]		$n(101) interface-errormodel [$val(err)]			# determine the actual queutype and save the one asked for 	# assign queueing parameters -- simulate random drop with RED	if { [string match RandomDrop* $queuetype ] } then {		set queuetype [join \				   [concat "RED" \					[string range $queuetype [string length "RandomDrop"] end ]]\				   "" ]		Queue/$queuetype set thresh_ [expr 2* $qlen]		Queue/$queuetype set maxthresh_ [expr 2* $qlen]		# added for ECN comparison		Queue/$queuetype set setbit_ $ecn	} elseif { [string match RED* $queuetype ] } then {		#added by nirav		Queue/$queuetype set bytes_ false		Queue/$queuetype set queue_in_bytes_ false		# Queue/$queuetype set q_weight_ = -1		# Queue/$queuetype set max_p = 1		Queue/$queuetype set gentle_ true		#added by nirav		#Queue/$queuetype set thresh_ [expr $qlen * 0.5]		#Queue/$queuetype set maxthresh_ [expr $qlen * 0.75]		Queue/$queuetype set thresh_ 0		Queue/$queuetype set maxthresh_ 0		# added for ECN comparison		Queue/$queuetype set setbit_ $ecn	}		# TCP flow	Agent/$tcptype set window_ $val(bdp) 	set tcp [$ns_ create-connection $tcptype $n(0) TCPSink/Sack1 $n(101) 0] 	set ftp [new Application/FTP] 	$ftp attach-agent $tcp 	$ns_ at 0.0 "$ftp start"	# tracing for sat links	$ns_ trace-all-satlinks $tracefd		# setup routing	set satrouteobject_ [new SatRouteObject]	$satrouteobject_ compute_routes	# trace for tcp parameters	$tcp trace cwnd_	$tcp trace t_seqno_	$tcp trace ndatapack_	$tcp trace nrexmitpack_	set tracef [open "$file.tcp_trace.$run" "w"]	$tcp attach $tracef 	# trace queue	#$ns_ trace-queue $n(0) $n(101) [open "$file.queue1" w]	# Stop the sim at $duration	puts "duration = $duration\n"	$ns_ at $duration "stop"	$ns_ at $duration "puts \"NS EXITING...\" ; $ns_ halt"		# start up.	puts "Starting Simulation..."	$ns_ run}	proc plot-ontime {} {	exec rm -f ontime	exec touch ontime	global file tracef	if [info exists tracef] { flush [set tracef] }	exec awk -v field=STATE -v off=1 {		{			if (($5 == $field) && ($6 == $off)) {				{ot += $8};			} 			{ print ot >> ontime; } 		}	} case0.tr}		         		  # traces are the set of info to be put outset traces [ list "TCP" "queue" ]# this boring code sets the given parameters from teh command line in order or# assigns defaults if they're not given.if { [llength $argv]>0} then { set run [lindex $argv 0]}\else {set run 1 }if { [llength $argv]>1} then { set retries [lindex $argv 1]}\else {set retries 3 }if { [llength $argv]>2} then { set model [lindex $argv 2]}\else {set model "urban" }if { [llength $argv]>3} then { set sources [lindex $argv 3]}\else {set sources 1}if { [llength $argv]>4} then { set duration [lindex $argv 4]}\else {set duration 300}if { [llength $argv]>5} then { set file [lindex $argv 5]}\else {set file "case0"}if { [llength $argv]>6} then { set qlen [lindex $argv 6]}\else {set qlen 50 }if { [llength $argv]>7} then { set tcptype [lindex $argv 7]}\else {set tcptype "TCP/Newreno"}if { [llength $argv]>8} then { set queuetype [lindex $argv 8]}\else {set queuetype "RED"}if { [llength $argv]>9} then { set seed [lindex $argv 9]}\else {set seed 12345}if { [llength $argv]>10} then { set c_sources [lindex $argv 10]}\else {set  c_sources 0}if { [llength $argv]>11} then { set delay [lindex $argv 11]}\else {set delay "10ms"}if { [llength $argv]>12} then { set rate [lindex $argv 12]}\else {set rate "100k"}if { [llength $argv]>13} then { set ecn [lindex $argv 13]}\else {set ecn 1 }# Start the simputs "run=$run, retries=$retries, model=$model, sources=$sources, duration=$duration, file=$file, qlen=$qlen, tcptype=$tcptype, queuetype=$queuetype, seed=$seed, c_sources=$c_sources"setup $tcptype $queuetype $sources $qlen $duration $file $seed $c_sources $delay $rate $ecn $run $retries