Event ID 18 — NLB Host Configuration

Updated: November 25, 2009

Applies To: Windows Server 2008 R2

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Hosts in a Network Load Balancing (NLB) cluster are configured to load balance network traffic. Host configuration is set by using NLB Manager, and if it is not configured properly, the NLB cluster may not function correctly.

 

Event Details

Product: Windows Operating System
ID: 18
Source: Microsoft-Windows-NLB
Version: 6.1
Symbolic Name: MSG_WARN_OVERLAP
Message: NLB cluster [%2]: NLB detected duplicate cluster subnets. This may be due to network partitioning, which prevents NLB heartbeats of one or more hosts from reaching the other cluster hosts. Although NLB operations have resumed properly, please investigate the cause of the network partitioning.

Resolve

Restart the NLB cluster

If Network Load Balancing (NLB) detects that there are duplicate subnets in the cluster, it may be due to network partitioning, which prevents NLB heartbeats of one or more hosts from reaching the other cluster hosts. You  may need to restart the NLB clustser to resolve this issue.

When you are using nlb.exe, you must be a member of the Administrators group on the host that you are configuring, or you must have been delegated the appropriate authority. If you are configuring a cluster or host by running nlb.exe from a computer that is not part of the cluster, you do not have to be a member of the Administrators group on that computer.

To restart the NLB cluster:

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type nlb.exe reload, which reloads the NLB driver's current parameters from the registry.
  3. Type nlb.exe start, which starts cluster operations on the specified hosts.

Verify

When you are using nlb.exe, you must be a member of the Administrators group on the host that you are configuring, or you must have been delegated the appropriate authority. If you are configuring a cluster or host by running nlb.exe from a computer that is not part of the cluster, you do not have to be a member of the Administrators group on that computer.

To verify that all Network Load Balancing (NLB) hosts are in the converged state:

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type nlb.exe query, which displays the current cluster state and the list of host priorities for the current hosts of the cluster.
  3. Confirm that all hosts display converged as their current state.

Related Management Information

NLB Host Configuration

NLB Cluster

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