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When you use Network Load Balancing (NLB) with a Layer 2 switch, load balancing clients may experience a brief, temporary disruption of service when a new NLB server is added to, or an "old" server is removed from the cluster.
During the protocol binding operation, the switch learns the cluster media access control address and binds it with the switch port associated with the new NLB server. Now load balancing traffic is sent only to that server rather than balancing the client traffic across all of the NLB servers. After a short period of time (approximately 5 minutes), the switch releases the cluster media access control address from the specific switch port in question.
To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
In order for NLB to work correctly with a Layer 2 switch, the cluster media access control address cannot be bound or associated with only one switch port.
Microsoft has confirmed that this is a problem in Microsoft Windows 2000.
This problem was first corrected in Windows 2000 Service Pack 1.
For additional information about NLB, click the article number below to view the article in the Microsoft Knowledge Base:
193602 Configuration Options for WLBS Hosts Connected to a Layer 2 Switches