A software interface between the transport protocol (layers 3 and 4) and the data link protocol (layers 1 and 2) in the protocol stack. The interface provides a protocol manager that accepts requests from the transport layer and activates the network adapter. Network adapters with compliant network drivers can be freely interchanged.
Multiple Protocols or Multiple Networks
The interface allows multiple transport protocols to be used with one network adapter. For example, a PC can send TCP/IP packets and SPX/IPX packets on the same network. It also allows one transport protocol to run over different physical networks, such as Ethernet and Token Ring. See TCP/IP
ODI and NDIS
In PC LANs, the two primary network driver interfaces are Microsoft's NDIS and Novell's ODI. Novell provides an ODI interface utility that allows NDIS and ODI protocols to work in the same computer. See NDIS