LLC Full Form is Logical Link Control (LLC) is one of the two sub-layers of the Data Link Layer which is in fact one of the seven layers of Open Systems Interconnection (OSI) model of communication. It is a data communication protocol. It is the upper sub-layer of Data Link Protocol.
The LLC is primarily and mainly concerned with multiplexing protocols that are transmitted over Media Access Control (MAC) layer and it also helps to decode them. It also efficiently provides synchronization, acknowledgement, node-to-node flow control and ARQ (Automatic Repeat Query) error management. It manages traffic over the physical medium. he LLC header helps the data link layer to understand what to do with a datagram packet that is received. It provides addressing and control of the data link.
It determines the addressing mechanisms for the addressing stations related to the transmitting medium and control the transmission and flow of the data exchange between the source and the destination. Line protocols like SDLC, NetBIOS, NetWare are also identified by the help of LLC. But, now-a-days better technology is being introduced and hence, LLC is only being considered as a multiplexing feature in the link layer protocols. More emphasis is given upon end-to-end protocols like TCP (Transmission Control Protocol).