use strict
use warnings
use diagnostics

my ($key, $system, $value, $vl1, $vl2, $vl3);
my %vlan = (
   "VLAN1" => $vl1,
   "VLAN2" => $vl2,
   "VLAN3" => $vl3,
)

-- LINES OMITTED --

print "VLAN1: ";
chomp ($vl1 = <STDIN>);
print "VLAN2: ";
chomp ($vl2 = <STDIN>);
print "VLAN3: ";
chomp ($vl3 = <STDIN>);

-- LINES OMITTED --

while (($key, $value) = each %vlan) {
   print "Now checking: $system\_$key $value";
   -- LINES OMITTED --
}

##</code><code>##

systemName_VLAN1 

##</code><code>##

systemName_VLAN1 1.1.1.1