High Level Data Link Control (HDLC)
HDLC was developed by ISO and has become the most widely accepted data link protocol. It offers a high level of flexibility, adaptability, reliability and efficiency of operation for today as well as tomorrow's synchronous data communication needs. ADCCP developed by ANSI is almost similar to HDLC, IBM'S SDLC is a proper subset of HDLC and level 2 of X-25 is a permissible option of HDLC. In this chapter, we shall study the basic features and operation of HDLC protocol. Certain liberties have been taken in the level of completeness of description so as not to cloud the overall picture with the details. GENERAL FEATURES of hdlc HDLC is a bit oriented data link control protocol which satisfies wide variety of data link control requirements including: · Point-to-point and point-to-multipoint links. · Two way simultaneous communication over full duplex circuits. · Two way alternate operation over half duplex or full duplex circuits. ·