"Data Link protocol for 'datalink name' ('device')?"

    Specify either HDLC, DDCMP, or NONE for the point-to-point data
    link protocol. The default is DDCMP.

    o  DDCMP (Digital Data Communications Message Protocol) provides
       synchronous point-to-point connections and asynchronous static
       or dynamic point-to-point connections.

    o  HDLC (High-Level Data Link Control protocol) conforms to the
       ISO standards. HDLC provides synchronous point-to-point links
       that function like DDCMP synchronous links.

    o  Enter NONE if either of the following statements is true.

       -  You do not want to run DECnet over this device

       -  You are using X.25 over this device