Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

A LAN driver is a workstation or server software module that provides an interface between a NIC (network interface card) and the upper-layer protocol software running in the computer. The driver is designed for a specific NIC. Drivers are usually installed during the initial installation of a network-compatible client or server operating system. The setup program asks which type of NIC is installed in the system and installs the appropriate driver. If the setup program does not have a driver, you are usually asked to insert a disk from the NIC manufacturer that contains a driver. The driver is then integrated into the protocol stack (or stacks) of the computer.

Figure L-2 illustrates where in the protocol stack the IEEE LAN drivers are located. The actual drivers are in the MAC (Medium Access Control) sublayer to the data link layer. The upper portion, called the LLC (Logical Link Control), provides a connection point for those drivers into the upper layers and acts as a software bus, delivering packets from upper layers to the appropriate LAN.