Cluster network role changes automatically (254651)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

If you lose network connectivity on both network adapters on a cluster network when the Media Sense feature is enabled, the network role in the server cluster for that network changes to All Communications (Mixed Network).

This may cause cluster resources to be bound to the network adapter that was to be used only for private cluster communications (typically, a isolated network). When this occurs, connectivity with domain controllers may be lost, which may cause the Cluster service on the surviving node not to work when you power off one of the nodes.

CAUSE

The default behavior for network Plug and Play Media Sense functionality is to destroy a network adapters's TCP/IP stack information when a media disconnect event occurs. The Cluster service receives notification of the network change and uses network failure detection code to make the network interface unavailable. The interface disappears from the cluster's list of enumerated networks because of the changes to the TCP/IP stack and the loss of information about the network.

If other nodes in the cluster are down during this event, the cluster network stops working and disappears from the Cluster Administrator tool entirely. When network connectivity resumes, the cluster detects the network as a new network interface and assigns it the default network role, which is All Communications (Mixed Network).

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

Set the DisableDHCPMediaSense registry value to 1 under the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

239924 How to disable Media Sense for TCP/IP in Windows 2000

If you set this registry value, it disables the Media Sense TCP/IP network information destruction procedure on all network interfaces in the system, regardless of whether they use DHCP-assigned or statically defined IP addresses. However, this setting still provides the Media Sense functionality for network adapters that support this feature.

MORE INFORMATION

For more information about network failure detection and recovery in a Windows 2000-based server cluster, see the following article in the Microsoft Knowledge Base:

242600 Network failure detection and recovery in a two-node Windows Server 2000 cluster