Smoothly transition from Exchange Server 2003 to Exchange 2010

Preparing your Active Directory and disabling link state updates will smooth the transition from Exchange Server 2003 to Exchange 2010.

When migrating from Exchange Server 2003 to Exchange Server 2010, you can't perform an in-place upgrade to Exchange Server 2010. Microsoft requires that organizations perform a clean Exchange Server 2010 installation onto a separate server and then to migrate mailboxes and public folder content to the new Exchange 2010 server.

This means that you'll need Exchange Server 2003 and Exchange 2010 to coexist either short-term -- a couple of hours -- or long-term. In either case, coexistence can be difficult because Exchange Server 2003 and Exchange 2010 are very different. This tip explains some of the key differences between the two versions and some of the tasks you'll have to perform as part of the transition.

Active Directory issues

Before deploying Exchange Server 2010 in an Exchange 2003 organization, you must prepare Active Directory and existing Exchange servers. This process isn't too labor-intensive; however, it does involve making a few irreversible changes to both Exchange and Active Directory. It's good practice to backup of all your Exchange servers and at least a couple of your domain controllers before starting.

You'll have to perform some the following configuration tasks:

  • Verify that any domain containing users with Exchange server mailboxes are set to Windows Server 2003 domain native mode.
  • Make sure that all of your global catalog servers are running Windows Server 2003 SP1 or higher. It's also acceptable to run Windows Server 2003 R2 or Windows Server 2008.
  • Ensure that your Active Directory schema master is running Windows Server 2003 SP1 or higher. Again, Windows Server 2003 R2 or Windows Server 2008 is acceptable.

    Check that any domain controller that's hosting a flexible single master operations role is running at least Windows Server 2003 SP1.

  • Set the Active Directory forest to Windows Server 2003 forest functional level.
  • Remove any Exchange 2000 or Exchange 5.5 servers from your organization and set the existing Exchange server to native mode.

Disable link state updates

More on Exchange Server 2010:
Leapfrogging from Exchange 2003 to Exchange 2010

What's new in Microsoft Outlook 2010?

Advice for virtualizing Exchange 2010 server roles

Exchange Server 2003 uses link state updates to keep track of which routes are used for to communicate between routing groups; however, Exchange Server 2010 doesn't use link-state updates. In smaller organizations, this architectural difference doesn't pose a problem; Exchange 2003 will continue to use link-state information. Exchange 2010 servers will ignore link-state updates.

In larger organizations, there are often multiple Exchange Server 2003 routing groups. You may have to create multiple routing group connectors between Exchange Server 2003 and Exchange 2010. In these situations, you must suppress minor link-state updates or routing loops may occur.

To disable minor link-state updates, modify the registry on each Exchange 2003 server. But this can be dangerous; making a mistake can often destroy Windows and Exchange Server.

To suppress link-state updates, open the Registry Editor and navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RESvc\Parameters

Right-click on the Parameters container and select the New | DWORD Value command. Name the new parameter SuppressStateChanges and assign it a value of 1. To finish, close the Registry Editor and restart the SMTP service, the Microsoft Exchange MTA stacks service and the Microsoft Exchange routing engine service.

About the author: Brien M. Posey, MCSE, is a five-time recipient of Microsoft's Most Valuable Professional (MVP) award for his work with Exchange Server, Windows Server, Internet Information Services (IIS), and File Systems and Storage. Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal website at

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