(I) HDLC frame format

(II) Data transfer modes

(III) Different HDLC frames

(IV) Importance of p/f bit

(V) Balanced and unbalanced configurations

(i) High-level Data Link Control (HDLC) is a bit-oriented protocol for communication over point-to-point and multipoint links. To provide the flexibility necessary to support all the options possible in the modes and configurations just described, HDLC defines three types of frames: information frames (I-frames), supervisory frames (S-frames), and unnumbered frames …