Encode a BFD Control packet without authentication section.

def pack(self):
        """
        Encode a BFD Control packet without authentication section.
        """
        diag = (self.ver << 5) + self.diag
        flags = (self.state << 6) + self.flags
        length = len(self)

        return struct.pack(self._PACK_STR, diag, flags, self.detect_mult,
                           length, self.my_discr, self.your_discr,
                           self.desired_min_tx_interval,
                           self.required_min_rx_interval,
                           self.required_min_echo_rx_interval)