A LAN driver is a software module designed as an interface between a Network Interface Card (NIC) and the upper layer software such as TCP/IP, IPX, NetBIOS, etc. LAN Drivers are functioning at the Medium Control Layer (MAC) sub-layer of the data link layer (layer 2). The Logic Link Control(LLC) layer, a sub-layer of layer 2 above the MAC layer, acts as a software bus providing connection between the driver and upper layers.

Drivers are normally installed in a PC, workstation or other network device during initial set up. Every network device manufacture may develop its own driver for their products being integrated into the network smoothly. Microsoft and Novell have developed interface support standards that enable more interface cards work with multiple network protocols. Microsoft’s standard is called Network Driver Interface Specification (NDIS), which defines a standard API for "Network Interface Cards" (NIC's). The details of a NIC's hardware implementation is wrapped by a "Media Access Controller" (MAC) device driver in such a way that all NIC's for the same media (e.g., Ethernet) can be accessed using a common programming interface. NDIS also provides a library of functions (sometimes called a "wrapper") that can be used by MAC drivers as well as higher level protocol drivers (such as TCP/IP). The wrapper functions serve to make development of both MAC and protocol drivers easier as well as to hide (to some extent) platform dependencies. Novell’s standard is called Open Data Link Interface (ODI). ODI maybe used on servers or workstations and allows computers to be connected to network with different communication protocols such as TCP/IP, IPX, AppleTalk, etc.

Related Terms: NIC, NetBIOS, MAC, LLC, NDIS, ODI, IPX, TCP/IP