Exchange Server 2010 : Installing OCS 2007 R2 (part 1) - Extending the Active Directory (AD) Schema & Preparing the AD Forest

OCS 2007 has a surprisingly complex installation process at first glance. What Microsoft has done, however, has been to divide up the installation process into multiple sections, providing for checks along the way so that there is less room for error. Because the installation requires an Active Directory schema upgrade, it is important that the process run smoothly, so it is good that this process is designed the way it is. It is important to note that OCS 2007 R2 is a 64-bit-only application and requires a 64-bit version of Windows Server to be installed.

Extending the Active Directory (AD) Schema

OCS 2007 integrates deep into an existing AD environment. It integrates so deeply, in fact, that an extension of the underlying AD schema is required before the product can be installed. AD schema upgrades are no small thing, of course, so it is wise to become familiar with the consequences of extending the schema and to make sure that a backup of the domain takes place first. To start the installation process, perform the following steps:

1.	When you insert the OCS media, the AutoRun brings you to a menu with a choice to install Standard Edition or Enterprise Edition.
2.	From this menu, click the Deploy Standard Edition Server link.
3.	You will be asked to install Microsoft Visual C++ and then the .Net Framework 3.5 from the media. Click Yes on both to continue. A reboot might be required when the installation finishes.
4.	Review the steps on the subsequent dialog box for the Deployment Wizard, shown in Figure 1. Click Prepare Active Directory. Figure 1. Deploying OCS 2007. Caution Installation of Office Communications Server 2007 R2 requires an AD schema upgrade to the AD forest. It is important to fully understand the consequences of a schema upgrade in advance, as an upgrade will replicate to all domain controllers in a forest. If there is already Office Communications Server 2007 in the forest, the schema update is still required for OCS 2007 R2.
5.	In the subsequent dialog box, shown in Figure 2, click Run to start the schema upgrade process. Figure 2. Starting the schema upgrade process.
6.	At the Schema Preparation Wizard welcome screen, click Next to begin the process.
7.	In the Schema File Location dialog box, leave the default location selected, and click Next.
8.	At the review screen, review the settings and, keeping in mind the caution previously given about schema upgrades, click Next to continue.
9.	The schema upgrade process will begin. When it is complete, click Finish.

After the schema update has run, be sure you wait until the new schema extensions have replicated to all domain controllers in the forest. After this has been verified, return to the Deployment Wizard to continue.

Preparing the AD Forest

After the schema extension is complete, perform the following steps:

1.	Return to the Deployment Wizard and click Run under Step 3: Prep Forest, as shown in Figure 3. Figure 3. Prepping the forest.
2.	Click Next at the welcome screen of the Forest Preparation Wizard.
3.	The subsequent dialog box, shown in Figure 4, gives you the option to choose between storing the global settings in the root domain, or in the configuration partition. In a single domain forest, choose the system container. In a multiple domain forest, choosing the configuration partition has some advantages. Figure 4. Choosing where to store global settings.
4.	Under Domain, choose the domain where OCS will create the groups used by the server. This is typically the main resource domain where the servers are installed into. Click Next to continue.
5.	Accept the default selection for the SIP Domain used for Default routing.
6.	At the review screen, click Next to continue.
7.	Click Finish.

After this step is complete, ensure that replication of the newly created objects has occurred on all domain controllers in the forest and proceed to the next step.