Re: [ns] i'm very new with ns

[Raymond Wang <rayw_94305@yahoo.com>]

# TCP connections between node_(0) and node_(2)
set tcp [new Agent/TCP]
$tcp set class_ 2
set sink0 [new Agent/TCPSink]
$ns attach-agent $n0 $tcp
$ns attach-agent $n2 $sink0
$ns connect $tcp $sink0
set ftp [new Application/FTP]
$ftp attach-agent $tcp

Thanks for the reply- as seen above, I did define it
above and I think it's correct.  So if it's not the
problem, what are some other possibilities?  Thanks so
much in advance!

--- "Marcos \"Locksmith\" Portnoi" <mportnoi@ieee.org>
wrote:
> Hey, it looks like my code!! :))
> 
> Check whether sink0 was defined properly outside the
> record procedure, and
> before it.  In my code, it is defined as
> set sink0 [new Agent/LossMonitor]
> $ns attach-agent $node $sink0
> 
> Portnoi
> ----- Original Message -----
> From: "Raymond Wang" <rayw@stanford.edu>
> To: <ns-users@ISI.EDU>
> Sent: Saturday, 29 de September de 2001 02:26
> Subject: [ns] i'm very new with ns
> 
> 
> > hi,
> >
> > i'm very new with ns.  here is a snippet of my
> code (actually borrowed
> from
> > someone with permission and i'm trying to
> understand it), why does it
> > result in the errors below?
> >
> > thanks a lot!
> > ray
> >
> > proc record {} {
> >          global sink0 f0
> >          #Get an instance of the simulator
> >          set ns [Simulator instance]
> >          #Set the time after which the procedure
> should be called again
> >          set time 0.5
> >          #How many bytes have been received by the
> traffic sinks?
> >          set bw0 [$sink0 set bytes_]
> >          #Get the current time
> >          set now [$ns now]
> >          #Calculate the bandwidth (in MBit/s) and
> write it to the files
> >          puts $f0 "$now [expr
> $bw0/$time*8/1000000]"
> >          #Reset the bytes_ values on the traffic
> sinks
> >          $sink0 set bytes_ 0
> >          #Re-schedule the procedure
> >          $ns at [expr $now+$time] "record"
> > }
> >
> > Errors:
> > ns: record: can't read "bytes_": no such variable
> >      while executing
> > "subst $[subst $var"
> >      (procedure "_o44" line 5)
> >      (Object next line 5)
> >      invoked from within
> > "_o44 next bytes_"
> >      ("eval" body line 1)
> >      invoked from within
> > "eval $self next $args"
> >      (procedure "_o44" line 18)
> >      (Agent set line 18)
> >      invoked from within
> > "$sink0 set bytes_"
> >      (procedure "record" line 8)
> >      invoked from within
> > "record"
> >
> >
> >
> 


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