Re: [ns] create-trace

[Haobo Yu <haoboy@isi.edu>]

> Could someone give me a simple tcl code that traces the packets that are
> dropped at q queue between 2 routers?
> The documentation says that on should use
> 
> $ns create-trace Drop $d $r0 $r1
> 
> where d is the file handle and r0 and r1 are the routers
> 
> what does this return and how shud it be used? doing just this gives and
> empty file with no data

This is the internal implementation of adding a drop trace object to a
link. In your simulation you probably want to simply turn on tracing on
that link using:

$ns trace-queue $n1 $n2 $file

this will write all packet traces on simplex link ($n1, $n2) into the file
handle $file.