THE TERMINAL SERVICES FAMILY

Microsoft Windows 2003 Terminal Services allows multiple users to log on to a Windows 2003 server, have their own desktop environment, and execute programs that stay resident. User logons effectively get their own protected memory space for applications and data. Users can have a Windows desktop and run Windows-based applications without the need to load the applications on their local PC. A server running Terminal Services can host hundreds of concurrent users (the specifics of server sizing will be covered in later chapters). In this chapter, we will use the generic term terminal server to refer to a server running Windows Server 2003 with Terminal Services enabled.

The client computing device used to communicate with the terminal server can be a PC or a specially designed terminal made to work with the Terminal Server display protocol. The PC or terminal runs a relatively small program that enables a logon and accepts redirected screen output from the terminal server. The Microsoft Terminal Services client program relies on a protocol originally developed for Microsoft's NetMeeting, called Remote Desktop Protocol (RDP). RDP is based on the International Telecommunications Union's (ITU) T.120 protocol. The T.120 protocol is a standard multichannel conferencing protocol that is tuned for enterprise environments and supports session encryption.

Terminal Services HistoryIt Started with

Windows NT 4.0 Server, Terminal Server Edition

Microsoft's Windows NT 4.0 Server, TSE, was the implementation of Citrix MultiWin (which will be discussed in Chapter 3) on the Windows NT 4.0 Server platform. Although Windows NT 4.0 is no longer officially supported by Microsoft or Citrix, it is worth discussing the beginnings of Terminal Services technology to further understand where it is today. For those still running Windows NT 4.0 TSE, we strongly recommend upgrading to Windows 2003 (see the following section, "Windows 2003 Server," for justification). If support for 16-bit applications is required, NT 4.0 Terminal Services Edition (TSE) is still necessary, as Windows 2000 and 2003 do not effectively support 16-bit applications.

Because of the MultiWin-inspired kernel of TSE, users could log on to virtual Windows NT 4.0 sessions with the same desktop and application look and feel of Windows NT 4.0 Workstation. With TSE, Microsoft created a separate code base for the operating system in order to overcome some of the memory management limitations of Windows NT 4.0 Server and to generally tune it for multiuser access.

Microsoft included their Terminal Server client, which is the client portion of the Remote Desktop Protocol, with TSE. This RDP client supported a variety of Windows desktops over TCP/IP networking, including Windows 95 and 98, Windows CE, Windows NT Workstation, Windows 2000, and Windows XP.

Windows 2003 Server

Windows Server 2003 is now the flagship product for Terminal Services. Packaged with the release of Windows Server 2003 is a new client connection program. The new Terminal Services client, first released with Windows XP, is called Remote Desktop Connection (RDC) and provides substantial improvements over previous releases, including greater functionality through a simplified user interface. RDC can also be used to connect to a Windows XP Professionalbased computer running Remote Desktop, and it can be used to connect to previous versions of Terminal Services (Windows NT 4Terminal Server Edition and Windows 2000 Server). RDC utilizes a new version of RDP and a new licensing model that provides for user and device licensing of Terminal Services and NT Client Access Licenses (CALs) rather than just device licensing that had been required (see the section "Licensing" later in this chapter). This licensing change represents a tremendous win for all Windows Terminal Services environments, as it dramatically reduces the costs for environments where users have more than one device they connect from. For example, under the Windows 2000 licensing model, if a user connected to a Terminal Services server or farm from a laptop, desktop, and home computer, Microsoft required the user's organization to purchase three Windows Terminal Services client access licenses and three Windows 2000 Server client access licenses for this one user. Under the new peruser licensing, the organization will need to purchase only one license for that user.

Windows 2003 Editions Comparison

Windows Server 2003 comes in six releases and four named editions: Standard, Enterprise, Datacenter, and Web. The Web edition will run on small-footprint servers. As the name implies, this edition is for Web servers onlysystems running IIS 6.0 and Web applications. This edition, for example, will make an excellent and cost-effective platform for Web services such as the Web Interface component of Citrix Presentation Server, as discussed in Chapter 16.

The Standard edition is the general-purpose version intended for traditional Windows Server tasks such as file and print serving, security, and Terminal Services.

The Enterprise edition is a " hardened " version of the operating system. Microsoft has added a number of features to this edition to increase its value as an application server platform. We envision that this server will be used for three potential purposes: large Terminal Services farms, clustering, transaction processing, or server consolidation. Note that the Standard and Enterprise editions are most likely to be used when Citrix Presentation Server is added on.

Finally, the Datacenter edition is the "big iron" version of the operating system. It is designed for the most demanding application and availability requirements where hardware cost is not a concern. This version requires a minimum of eight CPUs in a system and can run on systems containing up to 32 CPUs. System administrators who covet the chance to work on a Windows "mainframe" will be running this.

As mentioned, there are actually six releases. The additional two are the 64-bit versions of the Enterprise and Datacenter editions designed for the Intel Itanium processor. Because of the emphasis by the Microsoft SQL Server team on 64-bit computing, these releases will be targeted at high-volume database or transaction processing applications. Citrix has also released a 64-bit version of Citrix Presentation Server, and hence is also promoting the use of the 64-bit version of Enterprise edition for higher user density advantages.

Table 2-1 compares the features of the four named editions.

Table 2-1: Windows 2003 Editions Comparison

Feature	Standard Edition	Enterprise Edition	Datacenter Edition	Web Edition
Scalability
64-bit support for Intel
Itanium-based computers		+	+
Hot add memory [1] [2]		+	+
Non-Uniform Memory	Access (NUMA) [2]	+	+
Datacenter program			+
Maximum RAM Support
2GB	+	+	+	+
4GB	+	+	+
32GB		+	+
64GB [3]			+
512GB [4]
Maximum Symmetric Multiprocessing Support (SMP)
2-way	+	+	+	+
4-way	+	+	+
8-way		+	+
32-way			+
64-way			+
Directory Services
Active Directory	+	+	+
Metadirectory Services (MMS) support		+	+
Security Services
Internet connection firewall	+	+		+
Public Key Infrastructure, certificate services, and smart cards		+	+
Terminal Services
Remote Desktop for Administration	+	+	+	+
Terminal Server	+	+	+
Terminal Server Session Directory		+	+
Clustering Technologies
Network Load Balancing	+	+	+	+
Cluster service		+	+
Communications and Networking Services
Virtual private network (VPN) support	+	+	+
Internet Authentication Service (IAS)	+	+	+
Network bridge	+	+	+
Internet Connection Sharing (ICS)	+	+
IPv6	+	+	+	+
File and Print Services
Distributed File System (DFS)	+	+	+	+
Encrypting File System (EFS)	+	+	+	+
Shadow Copy Restore	+	+	+	+
Removable and remote storage	+	+	+
Fax service	+	+	+
Services for Macintosh	+	+	+
Management Services
IntelliMirror	+	+	+
Group policy results	+	+	+
Windows Management Instrumentation (WMI) command line	+	+	+	+
Remote OS installation	+	+	+	+
Remote Installation Services (RIS)	+	+	+
Windows System Resource Manager (WSRM)		+	+
.NET Application Services
.NET Framework [1]	+	+	+	+
Internet Information Services (IIS) 6.0	+	+	+	+
ASP.NET [1]	+	+	+	+
Enterprise UDDI services	+	+	+
Multimedia Services
Windows Media Services	+	+	+
[1] Not supported in 64-bit versions of Windows Server 2003. [2] May be limited by lack of support by OEM hardware. [3] Datacenter Edition's 32-bit version and Enterprise Edition's 64-bit version both support up to 64GB RAM. [4] The 64-bit version of Datacenter Edition supports up to 512GB RAM.