Re: [ns] Why 1 TCP source get more bandwidth than others in my script?

[John Mehringer <mehringe@ISI.EDU>]

Could you give us some more information?  I'm not entirely clear on what
your problem is.  It looks like you are getting valid output from your code.

Thanks,

- John Mehringer


"Young S. Choi" wrote:

> Hi.
>
> My simulation topology is...
>
> S1----|                                      |-----R1
>           |                                      |
> S2----|------G0-------G1------|-----R2
> .         |                                      |        .
> .         |                                      |        .
> .         |                                      |        .
> S20---|                                      |-----R20
>
> All links are 10Mbps and 10msec delay and Drop tail
>
> Here are the results
> ---------------------------------------------------------------
> ns app.tcl
> processing output ...
> Goodput per source:
> Goodput for source 0 : 330.20689655172413 kb/s
> Goodput for source 1 : 2337.1034482758619 kb/s
> Goodput for source 2 : 414.89655172413791 kb/s
> Goodput for source 3 : 485.51724137931035 kb/s
> Goodput for source 4 : 336.0 kb/s
> Goodput for source 5 : 392.27586206896552 kb/s
> Goodput for source 6 : 311.17241379310343 kb/s
> Goodput for source 7 : 426.48275862068965 kb/s
> Goodput for source 8 : 404.13793103448273 kb/s
> Goodput for source 9 : 395.58620689655174 kb/s
> Goodput for source 10 : 458.20689655172413 kb/s
> Goodput for source 11 : 373.51724137931035 kb/s
> Goodput for source 12 : 536.55172413793105 kb/s
> Goodput for source 13 : 398.34482758620692 kb/s
> Goodput for source 14 : 399.44827586206895 kb/s
> Goodput for source 15 : 359.17241379310343 kb/s
> Goodput for source 16 : 402.75862068965517 kb/s
> Goodput for source 17 : 416.27586206896552 kb/s
> Goodput for source 18 : 406.34482758620692 kb/s
> Goodput for source 19 : 327.17241379310343 kb/s
> ---------------------------------------------------------------
>
> Following are my code
> ----myapp.tcl----
> Class TraceApp -superclass Application
>
> TraceApp instproc init {args} {
>    $self instvar bytes_
>    $self instvar tempbytes
>    $self set bytes_ 0
>    $self set tempbytes 0
>    eval $self next $args
> }
>
> TraceApp instproc recv {byte} {
>    global ns
>    $self instvar tempbytes
>    set now [$ns now]
>
>    $self instvar bytes_
>    set bytes_ [expr $bytes_ + $byte]
>
>    return $bytes_
> }
>
> TraceApp instproc get_bytes {} {
>    $self instvar bytes_
>    return $bytes_
> }
>
> TraceApp instproc reset {} {
>    $self instvar bytes_
>    set bytes_ 0
> }
>
> set NUM  20
>
> set START 0
> set END  30.0
> set END_FILE 30.1
> set WINDOWSIZE 20
> set PACKETSIZE 1000
> set WARMUP 1.0
>
> set f [open out.tr w]
> for {set i 0} {$i < $NUM} {incr i} {
>  set fd($i) [open out-tcp$i.tr w]
>  set cfd($i) [open out-ctcp$i.tr w]
> }
>
> set ns [new Simulator]
> for {set i 0} {$i < $NUM} {incr i} {
>  set s($i) [$ns node]
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  set r($i) [$ns node]
> }
> set g0 [$ns node]
> set g1 [$ns node]
>
> $ns duplex-link $g0 $g1 10.0Mb 0.01ms DropTail
> for {set i 0} {$i < $NUM} {incr i} {
>  $ns duplex-link $s($i) $g0 10.0Mb 10.0ms DropTail
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  $ns duplex-link $r($i) $g1 10.0Mb 10.0ms DropTail
> }
>
> # trace the bottleneck queue
> $ns trace-queue $g0 $g1 $f
>
> Agent/TCP set window_ $WINDOWSIZE
> Agent/TCP set packetSize_ $PACKETSIZE
> for {set i 0} {$i < $NUM} {incr i} {
>  set tcp($i) [new Agent/TCP]
>  $ns attach-agent $s($i) $tcp($i)
>  set ftp($i) [new Application/FTP]
>  $ftp($i) attach-agent $tcp($i)
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  $tcp($i) set class_ $i
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  set sink($i) [new Agent/TCPSink]
>  $ns attach-agent $r($i) $sink($i)
>  set counter($i) [new TraceApp]
>  $counter($i) attach-agent  $sink($i)
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  $ns connect $tcp($i) $sink($i)
> }
> for {set i 0} {$i < $NUM} {incr i} {
>  $ns at $WARMUP "$counter($i) start"
> }
>
> #start
> for {set i 0} {$i < $NUM} {incr i} {
>  $ns at 0.0 "$ftp($i) start"
> }
>
> $ns at $END_FILE "finish"
>
> #Record for drawing Xgraph
> $ns at 0.0 "record"
> proc record {} {
>  global tcp sink fd cfd NUM
>  set ns [Simulator instance]
>  for {set i 0} {$i < $NUM} {incr i} {
>   set seqno [$tcp($i) set t_seqno_]
>   set cwnd [$tcp($i) set cwnd_]
>   set now [$ns now]
>   puts $fd($i) "$now $seqno"
>   puts $cfd($i) "$now $cwnd"
>  }
>  $ns at [expr $now+0.01] "record"
> }
>
> proc finish {} {
>  global ns f NUM counter END WARMUP
>  $ns flush-trace
>  close $f
>  puts "processing output ..."
>  exec cat out.tr | awk -f finish.awk > out
>
>  puts "Goodput per source:"
>  for {set i 0} {$i < $NUM} {incr i} {
>   set bytes [$counter($i) get_bytes]
>   set rate [expr $bytes*8/(1000*($END-$WARMUP))]
>   puts "Goodput for source $i : $rate kb/s"
>  }
>      exit 0
> }
>
> $ns run
>
> ---------------------------------------------------------------
>
> I don't know what this situlation is happen.
>
> Thanks a lot in advance,
> And with best regards...
>
> --
> Young S.Choi
> mailto:guru0109@palgong.knu.ac.kr
> ICQ : 93158371
> http://tenet2.knu.ac.kr/~guru0109
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