In continuing my discussion about the preparatory steps for moving down the path to Exchange Server 2000, I want to spend some time this week looking specifically at Windows 2000 (Win2K) and Active Directory (AD).
You'll recall from last week’s column that I wanted to get discussions of network design and TCP/IP issues out of the way before venturing into Win2K and AD territory. Win2K design and deployment will be a mess if your network is in trouble. For example, Win2K domain controllers and Global Catalog (GC) servers won’t be able to find each other or replicate if your DNS services aren’t working properly or supporting the necessary extensions (dynamic updates and service records). You need to look at your current Windows NT design, and make the changes required for Win2K. For many organizations, this is an ideal opportunity to fix what has been broken for a long time. My company had architectural issues (such as too many resource and master account domains) and used the move to Win2K as an opportunity for a fresh start. We redesigned the network and consolidated or eliminated resource and account domains. Don’t be lazy and roll out Win2K on top of your current NT design. Look at where your organization has come from and where it's going and design accordingly.
Closely related to Win2K network design is your AD design. You need to assess and plan how you'll deploy AD. First, you must understand AD replication (remember the importance of LDAP from last week. For a review, click here). Design a plan for upgrading your current NT environment. Will you roll-out a parallel design or will you upgrade your NT 4.0 domain controllers one by one to the AD? How will you populate the AD? Existing account information in the Exchange 5.5 directory is a great source. With the help of the Active Directory Connector (ADC), you can link the Exchange 5.5 directory to the AD and use the ADC to keep things synchronized during a phased deployment. As you plan for eventual Exchange 2000 rollout, coexistence between Exchange 5.5 and the AD will create challenges for things such as the Global Address List (GAL). Via connection agreements, the ADC can keep the GAL synchronized so that users on both sides (Exchange 2000 and Exchange 5.5) can view each other. Again, familiarity with LDAP and Microsoft’s DirSynch standard is invaluable here. GCs are another important element for successful Exchange 2000 deployment. The GC server is a special domain controller that sees beyond the local domain and has information about the entire forest. Exchange 2000 clients will need access to GCs to see the GAL, so GC placement in an Exchange organization is key. Successful AD replication and design and a good understanding of AD components such as the global catalog server will be important for Exchange 2000 deployment later. Ensure that you have a firm grasp on these subjects before proceeding.
Next week, I'll continue the discussion about planning and preparing for Exchange 2000 by covering topics such as software, hardware, and client assessment, and we'll finally look at Exchange 2000 deployment.