my %lookup = (
  mbps => 10**6,
  kbps => 10**3,
  bps  => 10**0,
  't1 line' => 100000
);

my $extract =
  sub {
        my $x = lc($_[0]);
        if ($x =~ s/^(\d+)\s*//) {
            $x = $1 * $lookup{ $x };
        } else {
            $x = $lookup{ $x };
        }
        die "Bad input $_[0]" unless $x;
        return $x;
      };
# etc.