This is more of a stats problem than it is a Perl problem, so I'm ready to take my lumps if the monks deem it necessary.

This script needs to compute average bandwidth utilization over a period of N years, and at X growth, as specified on the command line.

What we know:

1. 95th. percentile = 1.6 * average traffic.
2. When 95th. percentile reaches %80, we quadruple capacity.
In simple mathematical terms, when 1.6 * avg. traffic = .8/capacity, we quadruple capacity.

So, here's some code:

#!/usr/local/bin/perl -w

use strict;
use POSIX;


my $pct = $ARGV[0];
my $number_of_years = $ARGV[1];
my $beg_cap = 155;
my $beg_traffic = (.5 * $beg_cap);
my $m = (1 + $pct/100);

die "Usage: $0 <yearly growth percentage> <number of years>\n" unless 
+@ARGV ==2;
die "Not a valid percentage\n" unless($pct =~ m/\d+$/);
die "Not a valid year\n" unless ($year =~ m/\d+$/);

my $future_traffic = (($m**($number_of_years)) * ($beg_traffic));
print "future traffic: $future_traffic\n";

my $time_until_next_quadruple_cap = ((log(4)) / (log($m)));
print "time in years until next 4x increase: $time_until_next_quadrupl
+e_cap\n";

my $number_of_times_quadrupled = ceil($time_until_next_quadruple_cap);
print "number of times: $number_of_times_quadrupled\n";

my $new_cap = (4**($number_of_times_quadrupled));
print "new capacity = $new_cap\n";

my $abs_cap = (($new_cap * $beg_cap));
print "absolute capacity = $abs_cap MBpS\n";

my $util = (($future_traffic) / ($abs_cap) *.2705);
my $utilpct = ($util * 100);
print "avg. utilization = %$utilpct \n";
[download]

Anyone?