The Windows NT operating system ships with four network protocols:
Figure 1.12 Windows NT network protocols
Unlike the other protocols, the Data Link Control (DLC) protocol is not designed to be a primary protocol for network use between personal computers. DLC provides applications with direct access to the data-link layer but is not used by the Windows NT operating system redirector. Since the redirector cannot use DLC, this protocol is not used for normal-session communication between computers running Windows NT Server or Windows NT Workstation.
The DLC protocol is primarily used for two tasks.
Network-attached printers, such as the HP III, use the DLC protocol because the received frames are easy to take apart and because DLC functionality can easily be coded into read-only memory (ROM).
DLC needs to be installed only on those network machines that perform these two tasks, such as a print server sending data to a network HP printer. Client computers sending print jobs to the network printer do not need the DLC protocol; only the print server communicating directly with the printer needs the DLC protocol installed.
The registry location for the DLC parameters is:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DLC
The registry entry for the DLC driver indicates that it is loaded after the kernel has been started (Start 0x1), and it is dependent on having an NDIS group service available. Its linkage shows that it is bound to the network adapter by the appropriate NDIS device driver.
IBM introduced NetBIOS Extended User Interface (NetBEUI) in 1985. NetBEUI was developed for small departmental LANs of 20 to 200 computers. It was assumed that these LANs would be connected by gateways to other LAN segments and mainframes.
NetBEUI version 3.0 is included with Windows NT Server and Windows NT Workstation. It features the following advantages.
NetBEUI has two disadvantages.
The registry location for the NetBEUI parameters is:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NBF
The NetBEUI registry entry looks like the DLC entry. Like the DLC driver, NetBEUI is dependent on having an available NDIS group service. Also, under the linkage key, NetBEUI is bound to the network adapter entry by way of the NDIS device driver entry.
Strictly speaking, NetBEUI 3.0 is not truly NetBEUI because it is not inherently extending the NetBIOS interface. Instead, its upper-level interface conforms to the TDI. However, NetBEUI 3.0 still uses the NetBIOS Frame Format (NBF) protocol and is completely compatible and interoperable with previous versions of NetBEUI.
Network applications speaking directly to the NetBEUI 3.0 protocol driver now must use TDI commands instead of NetBIOS commands. This is a departure from earlier implementations of NetBEUI on MS-DOS and OS/2, which provided the programming interface as part of the transport's device driver. There is nothing wrong with this, but in the Windows NT operating system implementation, the programming interface (NetBIOS) has been separated from the protocol (NetBEUI) to increase flexibility in the layered architecture. Two points summarize the difference between these two.
TCP/IP is an industry-standard suite of protocols designed for WANs. It was developed in 1969, resulting from a Defense Advanced Research Projects Agency (DARPA) research project on network interconnection.
DARPA developed TCP/IP to connect its research networks. This combination of networks continued to grow and now includes many government agencies, universities, and corporations. This global WAN is called the Internet.
The Windows NT TCP/IP allows users to connect to the Internet and to any machine running TCP/IP and providing TCP/IP services.
Some of the advantages of TCP/IP protocol are that it provides the following functions.
The registry location for TCP/IP parameters is:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip
NWLink is an IPX/SPX-compatible protocol for the Windows NT network architecture. It can be used to establish connections between computers running Windows NT Server or Windows NT Workstation and MS-DOS, OS/2, and Microsoft Windows through a variety of communication mechanisms.
NWLink is simply a protocol. By itself, it does not allow a computer running Windows NT Server or Windows NT Workstation to access files or printers shared on a NetWare server, or to act as a file or print server to a NetWare client. To access files or printers on a NetWare server, a redirector must be used, such as the Client Service for NetWare (CSNW) on Windows NT Workstation or the Gateway Service for NetWare (GSNW) on Windows NT Server.
NWLink is useful if there are NetWare client/server applications running that use Sockets or NetBIOS over the IPX/SPX protocol. The client portion can be run on a Windows NT Server or Windows NT Workstation system to access the server portion on a NetWare server, and vice versa.
NWNBLink contains Microsoft enhancements to Novell NetBIOS. The NWNBLink component is used to format NetBIOS-level requests and pass them to the NWLink component for transmission on the network.
The registry location for NWLink parameters is:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NWLINK