Assessing Current Resources

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Once you have determined the needs of your users, the next step in planning your organization is to assess your current resources. To make this assessment, you must put together three diagrams: a diagram of your company's geographic profile, a diagram of your network topology, and a diagram of your Microsoft Windows 2000 networking model.

Defining Your Geographic Profile

The easiest place to start your assessment is with a geographic profile of your company. Get out a pen and paper, and start drawing maps. If your network is global, start with all of the countries in which your company has offices. Work your way down through states, cities, buildings, and even in-building locations.

Defining Your Software Environment

After you have a firm idea of how your company is laid out geographically, gather information on where users and resources are located within those geographical regions. This information helps you determine where the users are, where the computers are, whether the computers are ready for Exchange 2000 Server or your chosen messaging client, and how many licenses you are going to need. The following are a few considerations to think about along the way:

• Where are existing servers located?
• What are the servers' names and functions?
• What versions of which software are installed on the servers?
• How many workstations are in each location?
• What operating systems and software are used on those workstations?
• How many users are in each location?
• What are the users' needs?

Defining Your Network Topology

After you've created diagrams of your company's geographic profile, you need to diagram your company's network. Unlike the geographic profile, a network topology tells you exactly how your network is physically put together. When reviewing the geographic topology of the network, be sure to mark out the wide area network (WAN) links between the various locations and their bandwidths. This step will help you assess the site boundaries, the connectors required between sites, and the replication schedules. Figure 5-1 shows an example of a network diagram for a companywide WAN.

REAL WORLD   Systems Management Server

Ideally, you will already have a detailed inventory of your existing network assets. A comprehensive inventory includes a list of all of the hardware and software on all of the computers on your network. The inventory should also take into account how your network is constructed and maybe even some of the network's use statistics.

If you don't already have a network inventory, you could actually go to all of the computers on your network with notebook in hand. A better method, however, is to use an automatic inventory system such as that built into Windows 2000 Server or, for larger networks, Microsoft Systems Management Server (SMS). You can use Windows 2000 Server and SMS to gather hardware and software information from computers on your network automatically. You can also use SMS to push installations of software (such as messaging clients) to workstations throughout the network from a central location, to control and support client software remotely, and even to keep track of licensing information on your network. SMS really is must-have software for any up-and-coming Exchange administrator.

Note, however, that SMS is not a simple install-and-run application. Instead, it is a comprehensive, enterprise-capable network management software package. SMS requires SQL Server to provide the underlying database that captures and manages the network's data. To implement SMS and Microsoft SQL Server, you should have defined and executed a project plan and systems design.

For more details on the systems management capabilities built into Windows 2000 Server, see your product documentation. For more information on using Systems Management Server, check out the Microsoft Systems Management Server 2.0 Administrator's Companion by Steven D. Kaczmarek (Microsoft Press, 2000).

A clear definition of your network's topology allows you to plan site boundaries, site connections, and server placement and to understand replication issues. Whether your network is a single local area network (LAN) within one office building or a WAN connecting thousands of users around the world, you should design the Exchange organization to optimize its messaging functions over the network topology.

Areas that can be optimized include the following:

• Routing group definition
• Server placement
• Message routing
• Public folder replication

Figure 5-1. Diagramming your network topology.

The first step in defining a network topology is to determine the size of your network. The size of your network dictates how you will make many planning decisions and even whether you need to make them at all. On a large WAN, for example, especially one that is geographically dispersed, you might want to consider setting up multiple routing groups. Using multiple routing groups means that you have to consider such things as messaging connectors, directory replication, and public folder replication among sites. If you are setting up a relatively small LAN, you may decide to configure only one routing group in your organization, which makes many of these decisions much easier.

In a small company, all of your computers are likely to be connected on one high-speed LAN. In larger companies, networks usually consist of many small LANs connected in various ways to form larger, interconnected LANs or WANs. In your network topology diagram, you need to include all of the segments that make up your network. Figure 5-2 shows an example of a simple network diagram for a LAN.

Figure 5-2. Diagramming a LAN.

For each segment, ask yourself the following questions:

• How big is the segment? How many computers are there? How large a geographic area does the segment cover?
• How is the segment wired? Does it use thin or thick Ethernet, shared or switched Ethernet, 10 Mbps or 100 Mbps, Fiber Distributed Data Interface (FDDI), token ring, or something else?
• What is the bandwidth of the segment? Determine the optimal bandwidth according to the type of network being used. (See the Real World sidebar "Determining Bandwidth.")
• How is the segment connected to other segments? Is the network segment connected to the rest of the network directly; is it connected through a router, switch, or bridge; or is it connected through a WAN link? Is the connection permanent or switched? What is the bandwidth of the connection?
• What protocols are used on the network?
• What are the traffic patterns on the network segment? At what times of day is network traffic within the segment heaviest? What application and operating system functions account for this traffic?
• What are the traffic patterns between this segment and other segments? At what times of day is network traffic heaviest between segments? What application and operating system functions account for this traffic?

REAL WORLD   Determining Bandwidth

Although doing so can be somewhat tricky, you need to determine the available bandwidth of each segment of your network. The available bandwidth is the amount of bandwidth not consumed by average network activity. For example, if the throughput of a WAN link is 1.544 Mbps and the bandwidth consumed on that link can peak at 1.544 Mbps but averages around 512 Kbps (equivalent to 0.5 Mbps), the available bandwidth will be 1.544 Mbps – 0.5 Mbps, or 1.044 Mbps. You subtract the average value, not the peak value, because all network links experience peaks that don't represent the usual network bandwidth consumption.

Defining Your Windows 2000 Networking Model

The final step in assessing your current resources is to document your Windows 2000 networking model. Again, constructing a diagram is helpful. Whereas the topology diagram illustrates the physical layout of your network (cables, routers, etc.), the diagram of the networking model will illustrate the logical layout of your network. This logical layout includes how many domains your network has, how those domains are configured to interact, and the functions of those domains and the servers in them. Figure 5-3 shows a basic example of a Windows 2000 networking model.

Figure 5-3. Diagramming a networking model.

Although Exchange 2000 Server routing and administrative groups differ from sites and domains in Windows 2000, Exchange Server resources rely on domains to perform essential security operations. For example, to access an Exchange 2000 Server mailbox, a user must log on to a domain using a valid user account. Because Exchange 2000 Server services are Windows 2000 services, they too need to be authenticated by a domain controller before they can perform their functions. Each server in an Exchange organization is configured with a special user account called the Site Services account, which is used to validate Exchange services. For a detailed look at the integration of Exchange 2000 Server and Windows 2000 Server, see Chapter 4.

If your network contains only a single domain, the task of diagramming the networking model is easy. If your network consists of multiple domains, for each domain on your network, ask the following questions:

• What is the name of the domain?
• What is the function of the domain?
• What domains does this domain trust?
• What domains trust this domain?
• How many user accounts are configured in this domain?
• What resources are configured in this domain?
• Who are the administrators of this domain?
• In what domain are the user accounts of the administrators configured?

Putting the Diagrams Together

After you've diagrammed your networking model, it's helpful to see how the networking model diagram, the geographic diagram, and the network topology diagram fit together. No real rule defines how Exchange routing or administrative groups should correspond to Windows 2000 domains. It is tempting, and sometimes appropriate, simply to create a routing and administrative group for each domain. However, this approach does not always work. A single domain might cover several geographic regions that a routing group might not be able to span, due to the topology of your network. You may end up with one group spanning several domains, or you may end up with one domain spanning several groups. These decisions are more an art than a science—an art that is the topic of the next chapter.