Microsoft Windows NT
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With the same graphical interface as other versions of Windows and simple administration possible from the server console, Windows NT is a force to be reckoned with. Microsoft introduced Windows NT in 1993 with version 3.1 (about the same time Windows 3.1 was taking off as a desktop graphical interface for DOS). No one paid it much heed because it was fairly buggy, and a mountain of hardware was required to run it. This NOS went pretty much unnoticed until version 3.51 was introduced about a year later. Windows NT 3.51 was quite stable and, by this time, hardware vendors had met the challenge with the 486 and Pentium processors. Because of its similarity to Windows 3.1 and its powerful networking features, Windows NT gained popularity. Microsoft began to put its significant marketing muscle behind it, and Windows NT started to become a viable alternative in the network operating system market previously dominated by Novell NetWare and the various flavors of Unix.
| Note | For more information on Windows NT, check out Microsoft’s website at www.microsoft.com. |
Windows NT Features
Windows NT is the first choice of developers because of the similarity in programming for Windows 95/98 and Windows NT. Additionally, the installation CD includes a complete Internet server suite (including WWW, FTP, and DNS [Domain Name Service] server programs). Finally, because the look and feel of Windows NT is almost identical to that of Microsoft’s Desktop operating systems, Windows 3.x and Windows 95/98, training administrators requires much less time. These features along with many others have skyrocketed Windows NT use in the corporate network infrastructure. It is important to note that “Windows NT” actually refers to two separate products: Window NT Server (the NOS) and Windows NT Workstation (the client OS, designed to be a high-security desktop OS). Let’s take a look at a few of the more popular features of Windows NT.
The Windows NT User Interface
The Windows NT interface is the same as the Windows interface we’ve come to love (or hate, depending on your view). Windows NT 3.1 and 3.5x use the same basic look and feel as Windows 3.1. Windows NT 4 uses the interface from Windows 95 and Windows 98.
Although there might be subtle differences between the desktop operating systems and their Windows NT counterparts, the basic look and feel is the same. Because of this, a novice administrator can easily learn to use Windows NT. Analysts refer to this as a shallow learning curve.
Third-Party Support
Because of its ease of use and relatively inexpensive cost, Windows NT is selling well. Third-party vendors are writing thousands of software titles for Windows NT. Currently the number of third-party network programs for Windows NT surpasses the number for NetWare.
One reason for the range of software available for Windows NT is that developers can create these programs using many of the development tools they use to write Windows programs. Additionally, Microsoft makes much of the code available to developers for little or no charge. Other vendors often charge to download their development tools, although that trend is rapidly changing. Finally, a program that is certified as Windows Compatible must work on both Windows 95/98 and Windows NT. Because it’s so easy to develop programs for both versions and because Microsoft requires it for Windows certification, the number of programs available for NT is constantly growing. That isn’t to say that all NT programs are network enabled, but when given the choice, developers usually choose to create programs for NT rather than for other network operating system platforms.
Windows NT Interoperability
With the vast diversity of client operating systems out there, any network operating system must be able to provide services to multiple clients. For this reason, Windows NT Server includes file and print services for Apple Macintosh. The Windows NT server appears as if it were a Macintosh server.
Additionally, Windows NT can run text-mode native OS/2 programs without modification. For example, administrators with multiple OS/2 computers running OS/2 text mode e-mail gateways can consolidate them into a single Windows NT server and run each gateway in a separate window.
NetWare Integration
When Windows NT Server was released in 1993, NetWare was the primary network operating system available. As a matter of fact, it had more than 75 percent of the installed network operating system base. For this reason, Microsoft has software for Windows NT that allows it to coexist in a Net-Ware environment. Three main programs facilitate the integration of Windows NT and NetWare:
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Gateway Services for NetWare (GSNW)
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Client Services for NetWare (CSNW)
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File and Print Services for NetWare (FPNW)
Gateway Services for NetWare installs as a service on a Windows NT server and translates requests for Windows NT resources into NetWare requests. At a lower level, GSNW is translating SMB (Server Message Block) protocol requests into NCP (NetWare Core Protocol) requests. GSNW allows multiple Windows NT clients to connect through a Windows NT server to NetWare servers using only Windows NT client software and protocols. Figure 5.7 illustrates this arrangement.
Figure 5.7: Gateway Services for NetWare (GSNW) operation
| Note | GSNW has a relatively undocumented feature: Any number of Windows NT clients can connect to NetWare resources through GSNW and use only one license on the NetWare server being accessed. With this capability, it is theoretically possible to build a network of mostly NetWare servers, but license all of them for five users or fewer. Novell is understandably peeved. However, GSNW performance is very poor in this application. Microsoft doesn’t recommend GSNW for high NetWare traffic environments. |
Client Services for NetWare (CSNW) is probably the simplest of all the software, but it requires the most overhead to implement. You must install CSNW on every Windows NT Workstation computer that needs access to NetWare resources.
Additionally, all users who want to access NetWare resources need user accounts and rights on the NetWare servers they access.
File and Print Services for NetWare (FPNW) is really a method for providing files and printers hosted by Windows NT Server to Novell clients. When installed and configured on a Windows NT server, this service makes a Windows NT server look like a NetWare server to Novell clients. This service is good when you have a small number of NT servers and a large number of NetWare servers.
Windows NT Architecture
Windows NT sports a fairly complex architecture that’s hidden behind a nice graphical front end. This powerful operating system is available in two packages:
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Windows NT Server
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Windows NT Workstation
The two share the same basic underlying architecture, but there are several key differences. Table 5.4 details these differences.
| Feature | Windows NT Server | Windows NT Workstation |
|---|---|---|
| Maximum number of processors supported | 4 (a maximum of 32 with additional software components) | 2 |
| Maximum number of connections | Unlimited | 10 inbound, unlimited outbound |
| Support for Macintosh services? | Yes | No |
| Remote Access Service | A maximum of 256 sessions | 1 session |
| RAID (Redundant Array of Inexpensive Disks) support? | Yes | No |
| Can it perform NT domain authentication? | Yes (if the server is a domain controller) | No |
Application Support Subsystems
Windows NT is designed as a modular system. With this in mind, examine Figure 5.8. Components fall into either the user mode or the kernel mode. This simply indicates which entity uses those components.
Figure 5.8: Windows NT architecture
The two components to note in this diagram are the Hardware Abstraction Layer (HAL) and the many subsystems that can run applications. These two components enable NT to run many types of applications on many hardware types.
Win16 Applications (Win16 Subsystem)
Windows NT can run just about any 16-bit Windows application, providing that it conforms to the Microsoft standards for writing Windows 3.x applications. Each application can run in a separate Virtual DOS Machine (VDM) with its own memory protection.
Win32 Applications (Win32 Subsystem)
Windows NT can run applications designed for both Windows 95/98 and Windows NT.
OS/2 Applications (OS/2 Subsystem)
Windows NT can run OS/2 applications in character mode if these applications use only the pure OS/2 development tools. Windows NT cannot run OS/2 graphical applications.
Unix Applications (POSIX Subsystem)
One of the most talked-about features when Windows NT was introduced was its support for a standard Unix programming environment known as POSIX (Portable Operating System Interface for Computer Environments). Programs written to the POSIX standard can run on any POSIX implementation (including that of Windows NT). Windows NT can run any application that adheres strictly to the Institute of Electrical and Electronics Engineers (IEEE) POSIX standards.
Processor Options for Windows NT
In addition to the application support subsystems, Windows NT can run on many processor types. Before NT, most network operating systems ran only on the Intel platform. But the Hardware Abstraction Layer of the Windows NT architecture allows NT to run on different hardware platforms by simply using a different HAL. Currently, Windows NT supports the following CPU types:
Intel 386 (I386) Architecture Arguably the most popular platform for NT. This type includes the 80386, 80486, Pentium, Pentium Pro, Pentium II, and Pentium III as well as any newer processors in that line. A rule of thumb: If an I386 architecture runs DOS, it will run NT.
Digital Equipment Corporation (DEC) Alpha AXP Architecture Second only to the Intel architecture, this architecture has become popular because of the sheer speed of the DEC Alpha processor (now called Compaq Alpha). This is due, in part, to its Reduced Instruction Set Computing, or RISC, design.
MIPS R4x00 Architecture Another RISC processor that is gaining popularity. Windows NT and Unix are among the operating systems that run on the MIPS architecture.
Motorola PowerPC Architecture A RISC processor developed jointly by IBM, Motorola, and Apple. The Apple Power Mac and a version of the IBM PC use this processor. The Power Mac is now so popular among Macintosh users that all of Apple’s current line of Macintosh computers contains PowerPC-based units. The only operating system that the IBM PC implementation runs is Windows NT. And, unfortunately, Microsoft has announced plans to discontinue support for this architecture.
NT loads network applications as services. A service is a Windows program (a file with either an .EXE or a .DLL extension) that is loaded automatically by the server or manually by the administrator. Network applications that are written specifically for Windows NT are written as Windows NT services.
The Major Versions of Windows NT
In 1993, amid the increased popularity of networking PCs, Microsoft released Windows NT 3.1 as a high-end server platform for Windows networks. It was a powerful operating system that could take advantage of the 32-bit features of the Intel 386 processor, including support for as much as 4GB of memory and preemptive multitasking. However, its greater memory requirements and lack of stability with some programs made people nervous about adopting it as their only network operating system, and it was not widely adopted.
The release of Windows NT 3.51 in 1994 didn’t elicit an enthusiastic response. People quickly realized, however, that it was a stable, robust server platform that could be easily implemented in small- to medium-sized networks. Popularity and support for Windows NT grew in the computing community.
Windows NT 4, which was released in 1996, has the look and feel of Windows 95/98 and includes Internet Information Server (IIS), a web server, and the Internet Explorer web browser. This, in addition to simple server administration and RAID support, made Windows NT 4 the choice for many small- to medium-sized networks. It is becoming more widely used as an enterprise network, but has not been accepted as the backbone NOS for many large networks.
Microsoft changed that with Windows 2000 (formerly known as Windows NT 5), which was released in early 2000. The major difference between Windows 2000 and NT 4 is the replacement of the NT Directory Service (NTDS) with Microsoft Active Directory ( AD). AD is supposedly a true X.500-based Directory, similar to Novell’s NDS. In reality, it is a hierarchy of DNS names for domains (discussed in the next section).
Directory Services
As you already know, a directory service provides access to a central database of information that contains details about the resources available on a network. In Windows NT, the Security Accounts Manager (SAM) database (also called the domain database) contains information about all the users and groups within a domain. A domain is a group of computers that share a single SAM database. There can be more than one domain on a network. For the users in one domain to use resources that reside in a different domain, a relationship known as a trust must exist. This system of domains and trusts for a Windows NT Server network is known as Windows NT Directory Service (NTDS). Figure 5.9 illustrates a simple NTDS network.
Figure 5.9: An NTDS network
In an NTDS network, any computer that has Windows NT Server installed can have a copy of the domain database on it. However, only one copy of the database can be considered the master copy. This master copy is the only database responsible for initiating changes on the network. The computer that contains this master copy of the SAM is called the Primary Domain Controller, or PDC. Any other Windows NT server can have a copy of the SAM for backup purposes, in case something happens to the PDC. These computers are called Backup Domain Controllers (BDCs). Further, any computer that has NT Server installed, but doesn’t have a copy of the SAM, is called a Member Server. All of these server types are shown in Figure 5.9.
The importance of these distinctions is that all network administration for a domain happens at a PDC. BDCs can authenticate users, but if the PDC is down, you can’t make administrative changes (such as adding users) until the PDC comes back up. Member servers typically offer services to the network, but don’t take part in authentication (other than to indicate on which server the SAM database resides).
| Note | You can promote a BDC to a PDC without reinstalling, but, unfortunately, you can’t promote a Member Server to either a BDC or a PDC without completely reinstalling NT Server. |
In contrast to Novell NetWare, Windows NT has no one utility that you can use to manage all network entities and resources. Instead, user and group information is managed with User Manager for Domains. Figure 5.10 shows a sample screen from this utility, which you use to manage all users, groups, and policies for the domain. All users for this domain are shown in the top half, and all groups are shown in the bottom half. To select another domain, you must have previously established a trust with that domain. To select another domain and view its users and groups, choose User Select Domain.
Figure 5.10: User Manager for Domains
Even though Windows NT has its own directory service, Novell has been hard at work to implement its NDS on the Windows NT platform. NDS for NT completely replaces the Windows NT directory service while maintaining compatibility with Windows NT programs that rely on the NTDS.
Many people have tried to compare User Manager for Domains to Net-Ware Administrator, but their functionality is not the same. User Manager can deal with only one domain at a time, and then only with the users, groups, and policies of that domain. NetWare Administrator can manage the entire NDS tree and all network entities.
Minimum Requirements for Windows NT
Because of its graphical nature and complexity, Windows NT has greater hardware requirements than any of the other network operating systems. With each successive version, the hardware requirements seem to at least double, if not triple. The minimum hardware requirements and recommended hardware configuration for Windows NT 4 are listed in Table 5.5.
| Hardware | Minimum | Recommended |
|---|---|---|
| Processor | Intel 80486 or higher (I386 Architecture) or a supported RISC processor (MIPS R4x00, Alpha AXP, or PowerPC) | Pentium 90Mhz or higher (the faster the better) |
| Display | VGA | SVGA |
| Hard-disk space | 125MB free | 300MB free |
| Memory | 16MB | 32MB or greater |
| Network card | At least one that matches the topology of your network | At least one that matches the topology of your network |
| CD-ROM | Required | 4x or greater |
| Mouse | Required | Required |
In addition to the hardware listed in Table 5.5, Microsoft recommends running NT 4 Server on only the hardware in its Hardware Compatibility List (HCL). You’ll find the HCL at www.microsoft.com/hwtest/hcl/. If the hardware you are trying to use with Windows NT Server or Workstation isn’t on the HCL and you call Microsoft with a problem, you may have support difficulties.
Available Client Software
The nicest feature of Windows NT is less a feature than a fact of the state of networking today. If you implement Windows NT Server on your network, chances are you have Windows 95/98 as your client. All Windows 95/98 and Windows NT workstations install the Microsoft Client for Microsoft Networks by default whenever a network card is installed in a client workstation. This client enables the workstation to access any machine running a Microsoft operating system with networking components (for example, Windows NT Server or Workstation or Windows 95/98). This client must be installed to access the resources of a Windows NT network. Really the only client operating systems that can access a Windows NT network without additional gateway software on the server (such as the products for NetWare that were mentioned earlier) are Windows 95/98 and Windows NT versions of the Microsoft Client for Microsoft Networks.
Macintoshes can also access a Windows NT server, but Services for Macintosh (SFM) must be installed and configured. There is no Microsoft client for a Macintosh, per se. But there is an authentication module for the Macintosh that makes logons easier and provides a secure logon session for the Mac user.
In addition to the Microsoft Client for Microsoft Networks, Windows 95/ 98 and Windows NT include the Microsoft Client for NetWare Networks, which allows users to log in to NetWare servers. This client supports an NDS login, but doesn’t allow administration of an NDS tree using NetWare Administrator. When used in conjunction with the Microsoft Client for Microsoft Networks, this solution provides the most interoperability for clients in a network that has mostly NT servers and only a few NetWare servers, since they can log in to both Microsoft and Novell networks. The only caveat is that a user may not be able to access all the features on a NetWare server (including NDS, since this client performs bindery logins only).
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