sub mySort {
    
    $a =~ /(\d+)/;
    my $firstVal = $1;
    $b =~ /(\d+)/;
    my $secVal = $1;
    $firstVal <=> $secVal;
}

my %IP_Store = (
                "11.0.0.1" => "UEH1_system_ip",
                "11.0.0.11" => "UEH11_system_ip",
                "11.0.0.3" => "UEH25_system_ip",
                "11.0.0.25" => "UEH111_system_ip"
                );

%new_hash = reverse(%IP_Store);

foreach my $key (sort mySort (keys(%new_hash))) {
        chomp($key);
        print "$key\n";
        print "System_ip = $new_hash{$key}\n";
       #print "PDN-IP = '$Values' \n";
}