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Hdlc ppt..


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This presentation contains the brief description about the HDLC.

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Hdlc ppt..

  1. 1. PRESENTATION ON HIGH-LEVEL DATA LINK CONTROL Under The Guidance Of:- Submitted By:- Mr. Ashok Kr. Chauhan Prince Pal Singh Senior Lecturer B.Tech (4th Year) E.C.E Departmant E.C.E Dept.
  2. 2. CONTENTS 1. WHAT IS HDLC….? 2. HDLC TRANSFER MODES 3. HDLC FRAMES 4. FRAME FORMAT (a) Flag Field (b) Address Field (c) Control Field (d) Information Field (e) FCS Field
  3. 3. WHAT IS HDLC…???  High-level Data Link Control (HDLC) is a bit- oriented protocol i.e use bits to stuff flags occurring in data.  HDLC was defined by ISO for use on both point-to-point and multipoint data links.  It supports full-duplex communication i.e receive and transmit at the same time.
  4. 4. HDLC TRANSFER MODES  Unbalanced Configuration:-  Balanced Configuration:- Primary Secondary Secondary Commands Responses Combined Combined commands/Responses
  5. 5. CONTINUE….. 1. Normal Response Mode:-  In NRM, the station configuration is unbalanced i.e a primary station can only send commands; a secondary station can only respond.  The NRM is used for both point-to-point and multipoint links.  Here, the secondary station will send only when primary station instruct it to do so.
  6. 6. CONTINUE….. 1. NRM:- Fig:- Point-to-Point Links Fig:- Multipoint Links
  7. 7. 2. Asynchronous Response Mode:-  In ARM, the configuration is unbalanced like NRM only the difference is that here the secondary station is independent of the primary station. CONTINUE…..
  8. 8. CONTINUE….. 1. Asynchronous Balanced Mode  In ABM, the configuration is balanced.  Here, the link is point-to-point and each station can function as a primary and a secondary.
  9. 9. HDLC FRAMES HDLC FRAMES U-frame I-frame S-frame
  10. 10. CONTINUE…..  Unnumbered frames (U-frames) :- These frames are used in link set-up and disconnection.  Information frames (I-frames) :- These frames carry the actual information.  Supervisory frames (S-frames) :- S-frames are used only to transport control information.