πŸ“š What is LLC?

The Logical Link Control (LLC) is the upper sublayer of the Data Link Layer. It manages:

  • Framing
  • Error checking
  • Flow control
  • Interface to the Network Layer

LLC is defined in IEEE 802.2 and is common across many IEEE LAN standards (like Ethernet, Wi-Fi).

🧱 Framing

Framing is the process of encapsulating data with control information so that it can be transmitted over the physical medium. Each frame includes:

  • Header: Contains addressing and control info
  • Payload: Actual data from the Network Layer
  • Trailer: Often includes error-checking bits (e.g., CRC)

🧠 Deep Insight

Framing is how order emerges from chaos on the wire. Without it, streams of bits have no structure or meaning. LLC and framing define the grammar of digital communication.

β€œA frame is more than data β€” it’s context, identity, and integrity in motion.”

🧭 Types of Framing

  • Byte-oriented: Uses special characters (PPP)
  • Bit-oriented: Uses bit patterns with bit stuffing (HDLC)
  • Clock-based: Uses timing info (rare in LLC)

πŸ”— Links