my @sum_values;
my $x = 0;

foreach my $key ( keys %ifSpeeds )
{
	if ($counter <= 8) {
		$sum_values[$x] += $ifSpeeds{ $key };
		$counter++;
	} else { 
		$x++;
		$sum_values[$x] = $ifSpeeds{ $key };
		$counter = 1;
	}
}

for (my $x = 0; $x <= $#sum_values; $x++)
{
	print "$x) $sum_values\n";
}

##</code><code>##

   [0] --> (sum of Gi3/1 to Gi3/8)
   [1] --> (sum of Gi3/9 to Gi3/16)
   [2] --> (sum of Gi3/17 to Gi3/24)
   [3] --> (sum of Gi3/25 to Gi3/32)