Suppress Link State Updates

Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

Topic Last Modified: 2011-04-28

This topic explains how to use Registry Editor to suppress propagation of minor link state updates between routing groups in Microsoft Exchange Server 2010 and Exchange Server 2003.

We recommend that you perform this procedure if the following conditions are true:

You have installed the Exchange 2010 Hub Transport server role in an existing Exchange 2003 organization. For more information about this step, see Install Exchange 2010 in an Existing Exchange 2003 Organization.
The existing Exchange organization includes more than one Exchange 2003 routing group.
You will configure more than one routing group connector between Exchange 2003 routing groups and Exchange 2010.

The first routing group connector is created when the first Hub Transport server role is installed on a computer in the Exchange organization. Before you create additional routing group connectors, perform this procedure on every Exchange 2003 server in the organization. When you suppress minor link state updates, the servers running Exchange 2003 don't mark connectors as unavailable. This procedure makes sure that earlier versions of Exchange only use least cost routing and don't try to calculate an alternative route.

The purpose of this procedure is to make sure that routing loops can't occur. Exchange 2010 doesn't use a link state routing table and doesn't support relay of link state information. If you don't suppress minor link state updates, routing loops may occur. For more information about how routing occurs in an Exchange organization that includes Exchange 2010 servers and Exchange 2003 servers, see Upgrade from Exchange 2003 Transport.

Caution:
Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

Suppress Link State Updates on Exchange 2003

To perform this procedure, you must log on to the Exchange 2003 server by using an account that is delegated membership in the local Administrators group.

Open Registry Editor.
Locate HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RESvc\Parameters.
Right-click Parameters and select New | DWORD value. Name the new DWORD value SuppressStateChanges.
Double-click SuppressStateChanges.
In the Value data field, enter 1.
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.