IP Address Conflict Switching Between Unicast and Multicast NLB Cluster Mode (264645)


The information in this article applies to:

  • Microsoft Windows 2000 Advanced Server
This article was previously published under Q264645

SYMPTOMS

After you change the Network Load Balancing cluster mode from or to Unicast or Multicast in a cluster with two or more members, the following error message may appear:
The system has detected an IP address conflict with another system on the network. The local interface has been disabled. More details are available in the system event log. Consult your network administrator to resolve the conflict.

CAUSE

The cluster Unicast and Multicast media access control (MAC) addresses are different. The cluster MAC address changes on the host if you change the cluster mode to be different from the cluster MAC address on the other cluster host(s).

RESOLUTION

Remove the cluster IP address from TCP/IP properties before you change the cluster host. Before you add the IP address again after making the change, make sure that all cluster hosts are configured to use the same mode (Unicast or Multicast).

STATUS

This behavior is by design.

MORE INFORMATION

The IP address conflict error message is reported because two MAC addresses claim the same IP address.
Modification Type:MajorLast Reviewed:10/8/2002
Keywords:kbnetwork kbNLB kbprb w2000nlb KB264645
©2002 Microsoft Corporation. All rights reserved.