How to Set the SuppressStateChanges Registry Value


Exchange Server 2003 includes functionality to detect automatically changes in the state of a link. This information can be used to inform other servers running Exchange Server 2003 that an alternative route should be used instead of the lowest cost primary route. Link state information is divided into major and minor changes. A major change occurs when the administrator changes the routing topology, such as the addition of a new connector or a cost change. Minor updates occur when the system automatically detects the failure or restoration of a link.

This feature works well in small to medium-sized organizations. However, in large multi-site environments, mass network fluctuation can cause link update floods for the minor version. To be truly effective, link state data must be broadcast to all the servers in the organization. Additionally, when state changes, the whole link state table is rebroadcast, which can cause a significant amount of data to be transmitted over the network. In these scenarios, it may be useful to suppress minor link state changes. The SuppressStateChanges registry value is a custom configuration setting used to suppress minor link state changes. When SuppressStateChanges is set to a value of 1 (or any value greater than 0), all link state traffic generated by a connector state change on this Exchange Server computer are suppressed.

Before You Begin

Before you perform the procedure in this topic, be aware that the procedure contains information about editing the registry.


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.


To set the SuppressStateChanges registry value

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to HKLM\System\CurrentControlSet\Services\RESvc\Parameters.

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

  4. Double-click SuppressStateChanges.

  5. Set Base to Decimal.

  6. In the Value data field, enter 1.

  7. Close the registry editor and then restart the Simple Mail Transfer Protocol (SMTP), the Microsoft Exchange Routing Engine, and the Microsoft Exchange MTA Stacks services for the change to take effect.

For More Information

For information about how to edit the registry, see Microsoft Knowledge Base article 256986, Description of the Microsoft Windows Registry.