An enterprise SBC architecture has three major components: one or more data centers,
The data center is the heart of enterprise SBC architecture. Not only are all SBC applications and corresponding data hosted in the data center, but 100 percent of the hosted application processing occurs within the data center as well. The major data center components include the MetaFrame XP Presentation Server server farm, file servers and/or network attached storage (NAS) or storage area network (SAN) systems, other application servers, host systems, a fast server backbone, and a backup system. Figure 1-4 shows a sample on-demand enterprise data center.
Figure 1-4: A typical on-demand enterprise data center
Application execution occurs on the servers running Microsoft 2003 Terminal Services and Citrix MetaFrame XP Presentation Server. Because of the high resource demands made on these servers as well as the challenges involved in configuring them to run multiple applications without DLL conflicts or other problems, it is prudent to utilize at least two
Data is never stored on the MetaFrame XP Presentation Servers. Data is always stored on back-end file servers, application servers, NAS, or SAN systems.
Typical file servers in an SBC environment run a network operating system such as Windows Server 2003 or Novell. The servers feed files to the MetaFrame XP Presentation Server farm, maintain directory services, store user profiles, and sometimes handle printing functions. For larger SBC
In some SBC architectures, a storage area network (SAN) or network attached storage (NAS) will supplement the file servers, allowing organizations to store and access large amounts of data more
The rule of thumb is to have your MetaFrame XP Presentation Server server farm located wherever your data is stored. E-mail servers, SQL database servers, and all other application servers
Mainframe and minicomputer systems should be housed in the data center where they can be managed along with the Terminal Services hosting infrastructure. This enables organizations to leverage both their data center environmental resources and their support staffs. MetaFrame Presentation Server for UNIX is covered in Chapter 12.
A fast backbone should connect the MetaFrame XP Presentation Server server farm, the back-end file servers, and all other servers in the data center. This backbone should be either switched 100MB Ethernet, FDDI, ATM, or switched gigabit Ethernet. As with all data-center components, a redundant server backbone is desirable. This topic is discussed more thoroughly in Chapter 6.
A backup system should enable automatic backups of all servers. Tapes should be
SBC enables enhanced security by
The number of data centers utilized depends upon many
A single data center, despite internal redundancy,
SBC users often work at headquarters, at remote offices, and at home. At times, they are in hotels or at customer sites. They utilize PCs, laptops, Windows terminals, tablets, and handheld devices. Increasingly, they use specialty display devices that
PC users can access applications hosted at the data center in multiple ways. When PCs have a
Laptops typically run local applications when disconnected from the network. When connected to the network by a dial-up or wireless WAN connection, laptop users commonly launch a MetaFrame XP session. Extra training helps ensure laptop users do not confuse local applications with hosted applications. We have found that many employees of companies with SBC environments end up abandoning laptops except when on planes or in motels since they find it less cumbersome to use a PC or Windows terminal at both the office and home.
Nearly every major PC manufacturer, including IBM, Hewlett-Packard, and Dell, now makes Windows terminals. Many specialty companies, including Maxspeed, Neoware, and market leader, Wyse Technology, focus on building Windows terminals. Figure 1-5 shows one of the many models of Wyse Windows terminals. Windows terminals are typically display devices with no moving
Figure 1-5: A Wyse WinTerm Windows terminal
Because Windows terminals often have mean times between failure measured in decades, their maintenance expense is extremely low. If a Windows terminal does fail, IT simply delivers a replacement unit to the user. The user plugs in the Windows terminal, turns it on, and sees his or her desktop. Unlike PCs, Windows terminals do not allow users to destroy their unit configuration by loading
As the Internet's pervasiveness continues to grow, more organizations prefer to utilize browser interfaces. With the web interface component of MetaFrame XP Presentation Server, organizations can use their browser to launch published applications from the server farm. The web interface component also enables an organization's customers and suppliers to launch authorized applications through a browser. Different users with different logins will see different applications. This topic is discussed more thoroughly in Chapter 16.
MetaFrame XP Presentation Server requires between 10KB and 20KB of bandwidth per user session. This does not include additional bandwidth for large print jobs or for downloading or uploading files to and from a fat-client PC. When remote office applications are hosted at a corporate data center, they are completely dependent upon access to the MetaFrame XP Presentation Servers for all of their processing. An SBC architecture must include both adequate and reliable bandwidth connections along with redundant contingencies.
A frame relay circuit is the most popular connectivity method to multiple remote offices, though organizations increasingly utilize virtual private networks or straight Internet connectivity. Telecommuters, in particular, are using inexpensive fixed-fee Internet accounts to connect to corporate data centers. Bandwidth management is often desirable in order to prioritize ICA traffic. Bandwidth management devices from manufacturers such as Packeteer will prevent a user's large print job or file download, for example, from killing performance for the remaining users at a remote office. This topic is discussed more thoroughly in Chapters 6 and 17.
It sometimes makes more economic sense for regional headquarters and large remote offices to utilize their own MetaFrame XP Presentation Server server farms. This may also be true if the office uses software applications largely independent of, and different from, those employed at headquarters. Even in these scenarios, though, a common corporate database application, such as an ERP package, can still run off the MetaFrame XP Presentation Servers at the corporate data center. The regional offices can access this application by running the corporate ICA session within their own ICA session. This topic is discussed more thoroughly in Chapter 12.