Re: RED

[Bodog Gyula <s6356bod@hszk.bme.hu>]

Hi,

I have enough traffic. I used 8 and 32 FTP flow.
 In my simulation, I used the ECN bit to notify
congestion. As I looked the result (queue length, avg queue length), there's
congestion.
My problem is:

When I change the Linterm_ parameter from 4 to 100, result doesn't change.
I think, in this case, t should see the change in the result, but it doesn't
change.

Here my simulation script:



set ns [new Simulator]

set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

Queue/RED set thresh_ 20
Queue/RED set maxthresh_ 80
Queue/RED set q_weight_ 0.002
Queue/RED set setbit_ true

$ns simplex-link $n0 $n1 10M 0ms RED
$ns simplex-link $n1 $n2 45M 0ms DropTail
$ns duplex-link $n1 $n3 20M 0ms DropTail
$ns simplex-link $n2 $n3 20M 10ms DropTail
$ns simplex-link $n3 $n0 20M 10ms DropTail

$ns queue-limit $n0 $n1 240

Simulator instproc get-link {node1 node2} {
 $self instvar link_
 set id1 [$node1 id]
 set id2 [$node2 id]
 return $link_($id1:$id2)
 }

 set l [$ns get-link $n0 $n1]
 set q [$l queue]
 
$q set Linterm_ 4 

set qred [$l queue]
set avg [open avg w]

proc avgqueue {qred isti} {
global ns avg status

set maxpr [$qred set Linterm_]
set egz [$qred set ave_]
set cur [$qred set curq_]
set prob [$qred set prob1_]
set curt [$ns now]

puts $avg [format "%9.3f %9.3f %9.3f %9.3f %9.3f" $curt $egz $cur $prob
$maxpr]

$ns at [expr $curt + $isti] "avgqueue $qred $isti"
}

for {set i  0} {$i <12 } { set i [expr $i+0.001]}  {
$ns at $i "avgqueue $qred 12"
}


Agent/TCP set packetSize_ 1000
Agent/TCP set bugFix_ false
Agent/TCP set window_ 32K
Agent/TCP set ecn_ true

for {set i 0} {$i <8} {set i [expr $i+1]} {

set tcp(i) [new Agent/TCP/Reno]
set snk(i) [new Agent/TCPSink]
$ns attach-agent $n0 $tcp(i)
$ns attach-agent $n2 $snk(i)
$ns connect $tcp(i) $snk(i)
set ftp(i) [$tcp(i) attach-source FTP]
$ns at 0.0 "$ftp(i) start"
$ns at 12.0 "$ftp(i) stop"
}


for {set i 0} {$i <24} {set i [expr $i+1]} {

set tcp(i) [new Agent/TCP/Reno]
set snk(i) [new Agent/TCPSink]
$ns attach-agent $n0 $tcp(i)
$ns attach-agent $n2 $snk(i)
$ns connect $tcp(i) $snk(i)
set ftp(i) [$tcp(i) attach-source FTP]
$ns at 4.0 "$ftp(i) start"
$ns at 8.0 "$ftp(i) stop"
}

$ns at 12 "finish"


proc finish {} {

  
        global ns
        exit 0

}

                          

$ns run


Thanks in advance



 * * * * * * * * * * * * * * * * * * * * * * * * * * * *  
 *    Gyula Bodog                                      *
 *     e-mail: s6356bod@ural2.hszk.bme.hu              *
 *     tel.: (06 1) 3-691-839                          *
 *     Student at Technical University of Budapest     *
 *                                                     *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * *