Logical Link Control

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What Does Logical Link Control Mean?

Logical Link Control (LLC) is one of two Data Link Layer (DLL) network protocol sublayers within the Open System Interconnection (OSI) data communication model. LLC is located in the upper DLL area of OSI Layer 2 above the Physical Layer (PHY) of OSI Layer 1.

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LLC is standardized as IEEE 802.2 by the Institute of Electrical and Electronics Engineers (IEEE) .

Techopedia Explains Logical Link Control

The LLC multiplexing interface includes the following network protocol features:

  • Multipoint network operation
  • Unified network media exchange
  • Flow control
  • Line protocol identification, like Synchronous Data Link Control (SDLC)
  • Frame sequence number assignment
  • Acknowledgement tracking

Today, LLC is only used for its multiplexing feature. Modern Transport Layer protocols, like TCP or other application layer protocols, are used for source and destination network flow management.

A non-IEEE 802 protocol may be distributed between the LLC and Media Access Control (MAC) layers, like Cisco’s High-Level Data Link Control (HDLC).

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.