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Duties of IEEE 802.2 Logical Link Control (LLC)

In IEEE's version of Ethernet, the top sublayer of the Data link layer is Logical Link Control(LLC).

LLC' performs its functions in the software part of the Data Link Layer. LLC defines how to multiplex multiple network layer protocols in the data link layer frames. So, any logical operation in the Data Link Layer is happening in LLC.


Logical Link Control sublayer performs its multiplexing using Service Access Point (SAP) identifiers.


Let us check the IEEE definition of Logical Link Control(LLC). Logical Link Control sublayer comes under IEEE 802.2. There are two types of IEEE 802.2 frames. They are:


  1. Service Access Point(SAP)

  2. Subnetwork Access Protocol(SNAP)

Logic Link Control (LLC) has a few duties in the OSI reference model. Let us check them.


Duties of Logical Link Control(LLC)

  1. Multiplex multiple network layer protocols into frames.

  2. The second duty is Sequencing and flow control.


IEEE 802.2 uses the SAP(Service Access Point) or SNAP(Subnetwork Access Protocol) field to differentiate between encapsulated layer three payloads.


LLC is the top part of the Data Link Layer. So, it interacts with the Network layer.


  1. Local Area Network (LAN) - CCNA Study Material
  2. What is a Metropolitan Area Network (MAN)
  3. IEEE 802.11 WiFi Standards Backward Compatibility checker
  4. What Does ARP Do and How Does It Work?

IEEE 802.2 (LLC) concerns Ethernet, Token Ring, and FDDI. To read more about the MAC sublayer, visit the link below.

MAC Sublayer IEEE 802.3

Though LLC can do the sequencing and flow control, the Transport layer does it better. Let me explain how different the LLC and Transport Layer are in sequencing and flow control. LLC is limited to the same LAN. It does not work outside the LAN. To read more about different layers in the OSI Reference Model, click the link below.

OSI Reference Model
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