IEEE 802.2 refers to the Logical Link Control (LLC) standard for local area networks, specifically focusing on the Data Link Layer (Layer 2) of the OSI model. The Data Link Layer in the OSI model is divided into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC). While MAC addresses issues of frame synchronization, media access, and frame addressing, the LLC layer provides the interface for higher-level protocols and manages error and flow control.

Here are the key points regarding IEEE 802.2 – Logical Link Control (LLC):

Role: The primary purpose of LLC is to act as an interface between the upper layer protocols (like IP) and the MAC sublayer, which is responsible for actual frame delivery through the medium.

Service Access Points (SAPs): IEEE 802.2 defines SAPs that are used by the LLC to interface with higher-layer protocols.

Types of Services:

  • Unacknowledged connectionless mode: This is for simple datagram services without acknowledgment.
  • Connection mode: This mode sets up a connection before any data transfer begins and guarantees the delivery of packets.
  • Acknowledged connectionless mode: Data packets are sent with an acknowledgment, but no connection setup is required.

Frame Formats: IEEE 802.2 defines several frame formats, including Information frames (I-frames) for data and control information, Supervisory frames (S-frames) for control information, and Unnumbered frames (U-frames) for control and miscellaneous functions.

Compatibility: The LLC layer allows multiple higher-layer protocols (like IP or IPX) to operate over a common MAC layer. This means that a single physical network can carry traffic for multiple network layer protocols.

Extension: LLC can provide flow control and retransmission capabilities, extending the reliability of the Data Link Layer.

IEEE 802.2 is essentially a standard to ensure that various network protocols and technologies can operate seamlessly over common network architectures, like Ethernet. Its standardized approach helps in ensuring interoperability and consistency in data communications.