[ns] Re: your mail

[Haobo Yu <haoboy@isi.edu>]

you should use 'set jitter ...'

On Thu, 15 Jun 2000, tarik wrote:

> Date: Thu, 15 Jun 2000 10:03:55 -0700 (PDT)
> From: tarik <tarik@usc.edu>
> To: ns-users@mash.CS.Berkeley.EDU
> 
> Hi
>  I am trying to measure jitter between the two node but it gives me
> following error
> ns: dump _o15 1: can't read "jitter": no such variable
>     while executing
> "set $jitter [[expr $delay+1]-$delay]"
>     (procedure "dump" line 11)
>     invoked from within
> "dump _o15 1"
> 
> My script is
> 
> #set ns [new Simulator]
> set n0 [$ns node]
> set n1 [$ns node]
> $ns duplex-link $n0 $n1 5Mb 2ms DropTail
> ## Set up BSD Tahoe TCP connection in opposite directions.
> set src1 [$ns create-connection TCP $n0 TCPSink $n1 1]
> set src2 [$ns create-connection TCP $n1 TCPSink $n0 2]
> # Create ftp sources at the each node
> set ftp1 [$src1 attach-app FTP]
> set ftp2 [$src2 attach-app FTP]
> # Start up the first ftp at the time 0 and
> # the second ftp staggered 1 second later
> #$ns at 0.0 "$ftp1 start"
> $ns at 1.0 "$ftp2 start"
> ## Create a trace and arrange for all link
> # events to be dumped to "out.tr"
> #set tf [open out.tr w]
> $ns trace-queue $n0 $n1 $tf
> set qmon [$ns monitor-queue $n0 $n1 ""]
> set integ [$qmon get-bytes-integrator]
> ## Dump the queueing delay on the n0->n1 link
> # to stdout every second of simulation time.
> #proc dump { link interval } {
> 	global ns integ
> 	#global ns temp
> 	$ns at [expr [$ns now] + $interval] "dump $link $interval"
> 	set delay [expr 8*[$integ set sum_] / [[$link link] set
> bandwidth_]]
> 	#set $temp delay
> 	set $jitter [[expr $delay+1]-$delay]
> puts "[$ns now] jitter=$jitter"
> }
> $ns at 0.0 "dump [$ns link $n0 $n1] 1"
> ## run the simulation for 20 simulated seconds
> #$ns at 15.0 "$ns halt; exit 0"
> $ns run
> 
> Would you please what is  wrong here?
> 
> Thank!
> 
> KAt
> 
>