Generating ns traffic from a trace file

["Dr. Miroslav I. Klun" <mklun@gte.com>]

Gentlemen:


The section "The class TrafficGenerator" in "ns Notes and Documentation"
(May 11, 1999) states:

   "TrafficTrace--generates traffic according to a trace file.  Each
    record in the trace file consists of two 32-bit fields. The first
    contains the time in microseconds until the next packet is generated.
    The second contains the length in bytes of the next packet."


The ns distribution includes a canned example ns-2/tcl/ex/tg.tcl that
works with a trace-file-generated traffic. It uses its own trace file,
ns-2/tcl/ex/example-trace, which turns out to be a BINARY file, not ASCII.
(Note that the above description does NOT say anything about that!!!...)



But HOW can one create such a binary file?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


To be specific, we shall first describe here what we tried:


We started with a file "VIDEO" containing a video streaming dump:

13:30:19.620586 zeno.gte.com.1031 > 132.197.109.42.6970: udp 300
13:30:19.653737 zeno.gte.com.1031 > 132.197.109.42.6970: udp 541
13:30:19.723736 zeno.gte.com.1031 > 132.197.109.42.6970: udp 596
13:30:19.803739 zeno.gte.com.1031 > 132.197.109.42.6970: udp 604
13:30:19.894091 zeno.gte.com.1031 > 132.197.109.42.6970: udp 571
13:30:19.973717 zeno.gte.com.1031 > 132.197.109.42.6970: udp 610
13:30:20.053712 zeno.gte.com.1031 > 132.197.109.42.6970: udp 349
13:30:20.103723 zeno.gte.com.1031 > 132.197.109.42.6970: udp 617
13:30:20.183714 zeno.gte.com.1031 > 132.197.109.42.6970: udp 368
13:30:20.233723 zeno.gte.com.1031 > 132.197.109.42.6970: udp 611
.
.
.

The first column is the time stamp, the last is the packet size.
Extracting these only and expressing the time stamp in microseconds
(using a short Perl 5 program) one obtains a decimal ASCII file "DEC":

48619620586 300
48619653737 541
48619723736 596
48619803739 604
48619894091 571
48619973717 610
48620053712 349
48620103723 617
48620183714 368
48620233723 611
.
.
.

Expressing that in binary notation, using 32-bit fields, results
in the following file called "ZERO_ONE":

01010001111101001000100011101010 00000000000000000000000100101100
01010001111101010000101001101001 00000000000000000000001000011101
01010001111101100001101111011000 00000000000000000000001001010100
01010001111101110101010001011011 00000000000000000000001001011100
01010001111110001011010101001011 00000000000000000000001000111011
01010001111110011110110001010101 00000000000000000000001001100010
01010001111110110010010011010000 00000000000000000000000101011101
01010001111110111110100000101011 00000000000000000000001001101001
01010001111111010010000010100010 00000000000000000000000101110000
01010001111111011110001111111011 00000000000000000000001001100011
.
.
.

Now, this "ZERO_ONE" is again an ASCII file.  Replacing the aforementioned
file example-trace by this "ZERO_ONE" did not make tg.tcl work.

Then, we attempted to convert "ZERO_ONE" to a _binary_ file called "BINARY",
using the following Perl 5 program:


       #! /usr/bin/perl
       $z = "ZERO_ONE";
       $b = "BINARY";
       open(IN,"$z") || die "cannot open $z for reading";
       open(OUT,">$b") || die "cannot create $b";
       while (<IN>){
	   $line = $_;
	   $bline = pack("B*", $line);
	   print OUT $bline;
       }
       close(IN);
       close(OUT);


To our dismay, replacing the file "example-trace" by this "BINARY" did not
make tg.tcl work either.

(Incidentally, eliminating the blank space between the two 32-bit fields
in the file "ZERO_ONE" and then converting the result to a binary file
did not help!)

What was wrong?

In summary:

Could you please describe how to create a trace file from above VIDEO record?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thank you.


Regards,

Miroslav I. Klun

Network Infrastructure Laboratory
GTE Laboratories
Waltham, MA 02451
mklun@gte.com
(781)466-3830