Gathering and Analyzing Technical Requirements

When you're gathering and analyzing information about a business, you must consider the business requirements as well as the technical, security, and performance requirements. These three requirements have a major impact on the design of the Active Directory structure and must be carefully considered .

These factors are covered in the next three sections: "Determining the Technical Environment," "Assessing Security Requirements," and "Determining Performance Requirements." Keep in mind that these topics are equally as important as the previous ones discussed and are crucial in designing an effective Active Directory structure.

Determining the Technical Environment

To get a good overall picture of the technical environment in an organization, you need to look at the following aspects:

• LAN/WAN connectivity

• Available bandwidth

• Server and workstation distribution

LAN/WAN Connectivity

Begin the assessment of LAN/WAN connectivity by determining the topology of the network; document the network topology and the size of the network. After the layout of the network has been established, you can assess the connectivity between the physical networks. Documenting the connectivity in a business helps you in designing an Active Directory structure that complements the physical layout. Not doing a thorough assessment of the connectivity between and in the various locations can result in such things as regular replication occurring over a slow network connection.

The easiest thing to do to get an overall picture of the network structure is to draw a diagram representing the physical structure of the network. An example of this type of diagram is shown in Figure 3.4 (this will help give you an overall picture of the physical layout). After you've documented the physical layout, you can determine the type and speed of connections in the locations as well as the speed of the links between them.

Figure 3.4. An example of how the physical WAN structure of the XYZ Corporation might look. The design team can choose to document the physical structure in a similar way to get a better overall idea of the structure. In your diagram, be sure to also include the LAN structure.

Determining the appropriate speeds of the links in an organization depends on the amount of network traffic generated. Further analysis of the amount of network traffic generated throughout the business must be done to determine available bandwidth.

Completing these assessments helps the design team determine the best replication routes in the business and the optimum location for its servers.

Available Bandwidth

Assessing the amount of bandwidth available is necessary in determining the location of Active Directory sites. A connection between two locations might be high-speed and reliable, but if it is already heavily utilized, it might not have enough bandwidth available to support regular replication. This information can lead the design team to create sites on either side of the connection. Only a thorough analysis of the network traffic generated in an organization will give you a good picture of the available bandwidth, and using a network analyzer such as Network Monitor will help you determine the amount of traffic currently being generated.

The physical LAN and WAN infrastructure influences not only site design, but also domain design and server placement in a domain.

Figure 3.5 shows the speed of the WAN connections between the various locations in the XYZ Corporation (when doing an actual assessment of connectivity, be sure to include LAN connectivity as well as WAN). Creating a diagram similar to this one will help the design team establish an overall picture of the links available. After the type of connectivity has been established, the next step is to determine how much bandwidth is available over each link.

Figure 3.5. This figure shows the design team the exact speeds of the connections between the locations. The team would then have to assess the usage of each link to determine whether it would be capable of handling traffic generated by Active Directory replication.

When determining the amount of traffic generated on the network and the available bandwidth, consider some of the following traffic-generating events and how often they occur:

• How often are users required to change their passwords?

• How many users log on to the network?

• When do the bulk of the logons occur?

• How many DNS queries are performed throughout the day?

Server and Workstation Distribution

The design team is responsible for assessing how the servers and workstations are currently distributed throughout the organization. After the physical setup of the network has been documented, the design team needs to determine how many workstations are in each location, the number of servers in the business, and their current placements. The design of Active Directory sites is dependent on the number of workstations in each location. Therefore, the decision as to where domain controllers should be placed is partially dependent on the number of workstations in the various business locations.

For example, the design team working for the XYZ Corporation might determine during its assessment that one of the locations has a small number of workstations. Information such as this can help the design team later in determining whether a domain controller should be placed in this location.

It can be beneficial to add this information into your diagram of the physical network so you can get an overall picture of how the servers and workstations are distributed throughout the network.

Assessing Security Requirements

The security requirementsof a business have a major impact on the design of the Active Directory structure. The security plan developed by the design team should be based on the security requirements of the business. Security has become a hot issue when designing a network infrastructure. As the need for enterprise networks increases and the distribution of internal data among employees becomes a necessity, businesses are implementing strict security policies to secure their network resources. When assessing the security requirements of a business, you must consider user security needs and local (geographical) security requirements.

User Security Needs

Most businesses implement some form of security for their users to protect network resources and reduce the total cost of ownership (TCO). The security requirements a business implements for its users, such as data encryption for mobile users, application restrictions, and account restrictions, need to be considered when designing the Active Directory structure.

For example, the XYZ Corporation might have some of the following security requirements for its users:

• Preconfigured desktop for all users

• Limited capability for users to modify the configurations assigned to them

• Secure logon

• Application restrictions

• Sensitive data available to select groups

• Encrypted data for mobile users

The design team needs to be aware of these security requirements so the Active Directory structure can support them.

Local (Geographical) Security Requirements

The security of the users needs to be assessed, but consideration also must be given to the security needs of the various locations. Instances often occur in which one location in an organization has different security needs from another location. If this is the case, the design of the Active Directory infrastructure must reflect this.

For example, the XYZ Corporation has several locations throughout the world. After completing an assessment of the local security needs, the design team might determine that the offices in L.A. and the offices in Paris have different security requirements. Figure 3.6 shows a few of the security requirements for each of the geographical locations.

Figure 3.6. A list of some of the different security requirements that two of the locations in the XYZ Corporation might have.

The design of the Active Directory infrastructure for the XYZ Corporation needs to reflect the individual security needs of the locations in the business. To meet the different security needs of Paris and L.A., the design team might decide to create separate domains for each location. This would allow each of them to implement its own security. The point is that a company's security requirements have a major impact on the creation of forests, trees, domains, and OUs. Therefore, it's an aspect that deserves attention.

In particular, a critical aspect of domain design is understanding all the security requirements of an organization. Almost all security policy decisions are made at the domain level, so if part of an organization requires specialized security, the creation of multiple domains might be required.

Determining Performance Requirements

The performance requirements define the business and employee expectations for the network. The information gathered during this assessment assists you in creating a design that meets the expectations that have been expressed . Your goal should be to understand the performance requirements a business has and ensure that they are incorporated into the Active Directory design plans. Assess the performance requirements of both those in management positions as well as the end users.

For example, one of the expectations that the XYZ Corporation has expressed is that it does not want the WAN link between Paris and N.Y. to become saturated with replication traffic (refer to Figure 3.5). Being aware of this performance expectation, the design team could create two separate Active Directory sites between the two locations to enable the XYZ Corporation to schedule when replication traffic can occur over the WAN connection.