Recently I had the please of performing a migration from a 2003 AD environment which had pretty much no 2008 based DC's to an Exchange 2010 environment.

Exchange 2010 can only be installed on 2008 64bit based servers. With this in mind it obviuosly takes out the possibility of doing an in place upgrade from 2003. This article is aimed at providing a simple to follow process that you can implement to perform a migration. I stress that it is simple to give just a brief idea and you will need to do your own research to properly perform a migration in a production environment.

The first part will be about preparing the AD environment for Exchange and the second part will be about the process to install Exchange.

AD Preperation

Active Directory (2003) will need to be extended and prepared to be able to support Exchange 2010 based attributes. The process is as follows :

1. Ensure that you have added the feature "Remote administration tools for AD DS" if you are performing this on a non-DC server.
2. Run the following powershell command (as Administrator): "Import-Module ServerManager"
3. Insert Exchange 2010 CD and open command prompt (as administrator) from the setup directory.
4. Run command "Setup.com /PrepareLegacyExchangePermissions"
5. Run command "Setup.com /PrepareSchema"
6. Run command "Setup.com /PrepareAD"
7. Run command "Setup.com /PrepareDomain"

Replicate AD and once finished your environment is now ready for Exchange 2010 preperation.

Exchange 2010 Installation

Exchange 2010 installation process basically runs the setup wizard and installs the relevant Exchange 2010 roles. The most basic install will require the Client Access/Hub Transport/Mailbox Roles.

Before installation make sure that your 2003 based servers do not replicate link state information by performing the following registry change:

1) Open Registry Editor.

2) Locate 
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RESvc\Parameters.

3) Right-click Parameters and select New | DWORD value. Name the new
DWORD value SuppressStateChanges.

4) Double-click SuppressStateChanges.
 In the Value data field, enter 1.

5) Close Registry Editor, and then restart the SMTP service, the Microsoft Exchange Routing Engine service, and the Microsoft Exchange MTA Stacks services for the change to take effect.

Before performing the actual Exchaneg installation, ensure that you have performed a windows update to the latest patches (I really stress this point) and you have installed the Microsoft filter Packs http://go.microsoft.com/fwlink/?LinkID=191548.

Execute Setup.exe from the Exchange 2010 media. Choose the language packs on the DVD and run install.

Setup will ask a few questions (which roles, location, e.t.c), ensure you specify the correct external URL for CAS and choose a server for the routing between 2003 and 2010 Exchange. GO grab a cup of coffee as it will do its own thing for the next 20 minutes or so.

Post Installation

Once Exchange ha sbeen installed there are a few things you will need to take care of:

1. Configure a send connector to route outbound email
2. Configure a recieve connector to recieve email on port 25 from all IP addresses (and for anonymous authentication if it is to recieve internet email).
3. Configure external/internal URL for OWA
4. Enable Outlook Anywhere (will need to forward ports 443,6001-6004 to the CAS server)
5. And whatever your organisation needs....