Logical Link Control (LLC) is the upper part of the data link layer in a local area network. The LLC protocol is defined in IEEE 802.2. The data link services of users provide a unified interface for the network layer through the LLC sub-layer. Below the LLC sub-layer is the MAC (Media Access Control sub-layer). In the IEEE standard, this sub-layer was added. This sub-layer ensures transmission across different network types by adding an 8-bit destination address and an 8-bit source address to the IP packet to serve as access points for the destination and source. Additionally, there is an 8-bit or 16-bit control field used for auxiliary functions such as flow control.