[ns] queue

["Cavallin L." <lcavallin@run.montefiore.ulg.ac.be>]

I would like to monitor queue size, I tried this but it seems doesn't
work:

$ns_ duplex-link $node_(2) $node_(3) 1Mb 2ms DropTail
$ns_ queue-limit $node_(2) $node_(3) 28
set queue_tr(0)  [open "output/queue_2-3.tr" "w"]
set queue_(0) [$ns_ monitor-queue $node_(2) $node_(3) ""]

proc trace_queue { } {
    global queue_ queue_tr ns_
    set interval 0.10
    set now [$ns_ now]
    set s [$queue_(0) set size_]
    set p [$queue_(0) set pkts_]
    puts $queue_tr(0) "$now $s $p"
    $ns_ at [expr $now + $interval] "trace_queue"
}

$ns_ at 0.0 "trace_queue"

but the file queue_2-3.tr contains this:
0 0 0
0.10000000000000001 0 0
0.20000000000000001 0 0
0.30000000000000004 0 0
0.40000000000000002 0 0
0.5 0 0
0.59999999999999998 0 0
0.69999999999999996 0 0
0.79999999999999993 0 0
0.89999999999999991 0 0
0.99999999999999989 0 0
1.0999999999999999 0 0
1.2 0 0
1.3 0 0
1.4000000000000001 0 0
1.5000000000000002 0 0
1.6000000000000003 0 0
1.7000000000000004 0 0
1.8000000000000005 0 0



What is it wrong??