Suggest an editImprove this articleRefine the answer for “What is the LLC sublayer?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**The LLC sublayer (Logical Link Control)** is the **upper sublayer of the data link layer**, responsible for logical connection management and interaction with the network layer. **Key point:** in practice, on Ethernet most LLC functions are almost never used, since higher layers (TCP) take them over.Shown above the full answer for quick recall.Answer (EN)Image**The LLC sublayer (Logical Link Control)** is the **upper sublayer of the data link layer**, responsible for **logical connection management and interaction with the network layer**. Put simply: **LLC is the "intermediary" between the data link layer and the network layer**, which makes the data link layer's work more universal and independent of the specific technology (Ethernet, Wi-Fi, etc.). --- ## Where the LLC sublayer sits The data link layer is split into two sublayers: - **LLC (Logical Link Control)** - the upper one, this one - **MAC (Medium Access Control)** - the lower one LLC: - is closer to the **network layer** - does not depend on the type of physical medium --- ## Main tasks of the LLC sublayer ### 1. **Connection to the network layer** LLC: - receives data from the network layer (for example, IP) - passes it to the MAC sublayer - in the reverse direction, passes data upward Thanks to LLC, the network layer **does not need to know** which technology is used for transmission. --- ### 2. **Identifying the upper-layer protocol** LLC indicates: - which protocol is inside the frame (IP, ARP, etc.) This is needed so that: > data is correctly delivered to the right protocol above --- ### 3. **Logical transmission control** In its classic form, LLC can: - manage the logical connection - ensure ordering - (optionally) participate in error control In practice, on Ethernet most of these functions are **almost never used**, since higher layers (TCP) take them over. --- ### 4. **Independence from the data link layer technology** LLC makes it so that: - IP can work over Ethernet - IP can work over Wi-Fi - IP can work over other L2 technologies Without any changes at the network layer. --- ## What LLC does NOT do Important for an interview: LLC: - does not manage access to the medium - does not work with MAC addresses - does not interact directly with the physical layer That is handled by the **MAC sublayer**. --- ## Simple analogy An office secretary: - receives documents - understands which department to send them to - does not care exactly how they get delivered --- ## MAC + LLC together (very briefly) - **MAC** - *how and over what to transmit* - **LLC** - *what is transmitted and who to hand it to above* --- ## Short version for an interview > **The LLC sublayer** is the upper part of the data link layer that provides a logical link to the network layer, identifies upper-layer protocols, and makes data transmission independent of the specific L2 technology.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.