Chapter Summary

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The following points summarize the key concepts of this chapter:

OSI Reference Model

• The OSI reference model architecture divides network protocols into seven layers: the application, presentation, session, transport, network, data-link, and physical layers.
• Microsoft Windows NT groups the OSI reference model into three layers: file system drivers, transport protocols, and NIC drivers.
• The Windows NT network model requires three interfaces to provide communication between groups: APIs, TDIs, and NDISs.

IEEE 802.x

• IEEE 802 standards define the specifications for NICs, WAN components, and media for the data-link and physical layers of the OSI reference model.
• 802.3 defines Ethernet specifications.
• 802.5 defines Token Ring LAN specifications.
• The IEEE 802 standards divide the data-link layer into two subgroups: Logical Link Control (LLC) and Media Access Control (MAC).

Device Drivers and OSI

• A driver is a program that gives directions to the computer for how to operate a device.
• In networking, drivers are needed to provide the software connection between the computer and the NIC.
• NIC drivers reside in the MAC sublayer of the data-link layer of the OSI reference model.
• NDIS is a standard that defines the interface for Windows NT Server and Warp Server.
• ODI is a standard that defines the interface for Apple and Novell systems.