sub recursive_print_traversal {
        $parent = shift;                # the parent

        $addr = "select * from address_tbl where Subnet='$parent'";
        $subs = "select * from subnet_tbl where VLAN='$parent'";

        $addr_str = $dbh->prepare($addr);       # prepare address select
        $subs_str = $dbh->prepare($subs);       # prepare subnet select


        $addr_rst = $addr_str->execute();       # execute address select
        $subs_rst = $subs_str->execute();       # execute subnet select