Explain High Level Data Link Control.

HDLC - it is High Level Data Link Control:

Protocol Overall explanation:

Layer 2 of the OSI model is the data link layer. One of the most common layers 2 protocols is the HDLC protocol. The fundamental framing structure of the HDLC protocol is demonstrated below:

HDLC uses zero deletion/insertion process (commonly termed as bit stuffing) to make sure that the bit pattern of the delimiter flag does not arise in the fields among flags. The HDLC frame is synchronous and hence relies on the physical layer to give method of clocking and synchronizing the reception and transmission of frames. The HDLC protocol is defined through ISO for utilization on both point-to-point and multipoint (multidrop) data links. This supports full duplex transparent-mode operation and is at this time extensively used in multipoint and computer both networks.

High Level Data Link Control has three operational modes as:

a) Normal Response Mode (NRM)

b) Asynchronous Response Mode (ARM)

c) Asynchronous Balanced Mode (ABM)