IEEE 802.2

IEEE 802.2 is the original name of the ISO/IEC 8802-2 standard which defines Logical Link Control (LLC) as the upper portion of the data link layer of the OSI Model. The original standard developed by the Institute of Electrical and Electronics Engineers (IEEE) in collaboration with the American National Standards Institute (ANSI) was adopted by the International Organization for Standardization (ISO) in 1998, but it still remains an integral part of the family of IEEE 802 standards for local and metropolitan networks.

LLC is a software component that provides a uniform interface to the user of the data link service, usually the network layer. LLC may offer three types of services:

Conversely, the LLC uses the services of the Media Access Control (MAC), which is dependent on the specific transmission medium (Ethernet, Token Ring, FDDI, 802.11, etc.). Using LLC is compulsory for all IEEE 802 networks with the exception of Ethernet. It is also used in Fiber Distributed Data Interface (FDDI) which is not part of the IEEE 802 family.

The IEEE 802.2 sublayer adds some control information to the message created by the upper layer and passed to the LLC for transmission to another node on the same data link. The resulting packet is generally referred to as LLC (PDU) and the additional information added by the LLC sublayer is the LLC HEADER. The LLC Header consist of DSAP (Destination Service Access Point), SSAP (Source Service Access Point) and the Control field.

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