Logical Link Control

Logical Link Control

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Logical Link Control (LLC) is a sublayer of the Data Link Layer in the OSI (Open Systems Interconnection) reference model for computer networking. It provides services for establishing and maintaining reliable data transmission between network nodes. Here are some key points about Logical Link Control:

  1. Definition: LLC is responsible for managing the logical link between network nodes and providing error-free and reliable data transmission.
  2. Data Link Layer: LLC is a component of the Data Link Layer, which is responsible for transferring data between adjacent network nodes.
  3. Reliable Data Transmission: LLC ensures the reliable delivery of data by implementing error detection and correction techniques. It uses protocols such as ACK (acknowledgment) and NAK (negative acknowledgment) to confirm successful data transmission or request retransmission.
  4. Flow Control: LLC regulates the flow of data between network nodes to prevent congestion or data loss. It employs techniques like windowing and buffer management to control the rate at which data is sent and received.
  5. Frame Formatting: LLC encapsulates higher-layer data into frames with specific formatting, including header and trailer information. This formatting allows for proper identification and synchronization of frames during transmission.
  6. Addressing: LLC uses unique addresses, such as MAC (Media Access Control) addresses, to identify network nodes and facilitate communication between them.
  7. Multiplexing and Demultiplexing: LLC supports multiplexing and demultiplexing of data streams from different network protocols. It enables multiple network protocols to share the same physical network medium.
  8. Network Layer Independence: LLC provides an interface between the Data Link Layer and higher-layer protocols, allowing network protocols above it to operate independently of the specific network technology or physical medium being used.
  9. Compatibility: LLC is designed to be compatible with various network technologies and protocols, making it adaptable to different network environments.
  10. Standards: The LLC sublayer is standardized by organizations such as the Institute of Electrical and Electronics Engineers (IEEE), with IEEE 802.2 being a common standard for LLC.

LLC plays a critical role in ensuring reliable and error-free data transmission within a network. By providing services for flow control, error detection and correction, and addressing, LLC contributes to the overall efficiency and effectiveness of data communication between network nodes.

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