run layer specific checks

def _check(self):
        """
        run layer specific checks
        """
        if conf.contribs['LLDP'].strict_mode():
            management_address_len = len(self.management_address)
            if management_address_len == 0 or management_address_len > 31:
                raise LLDPInvalidLengthField(
                    'management address must be  1..31 characters long - '
                    'got string of size {}'.format(management_address_len))