HDLC – High-Level Data Link Control

• Formal standard developed by ISO

• Same as SDLC, except

  • Longer address and control fields
  • Larger sliding window size
  • And more

• Basis for many other Data Link Layer protocols

  • LAP-B (Link Accedes Protocol – Balanced)
    • Used by X.25 technology
  • LAP-D (Link Accedes Protocol – Balanced)
    • Used by ISDN technology
  • LAP- F (Used by Frame Relay technology)

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