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Event ID 50 — Network Adapter Functionality

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Applies To: Windows Server 2008

The network adapter to which Network Load Balancing (NLB) is bound must be properly configured and capable of performing NLB operations. If the adapter is not properly configured, the NLB driver may fail to bind to the adapter.

Event Details

Product: Windows Operating System
ID: 50
Source: Microsoft-Windows-NLB
Version: 6.0
Symbolic Name: MSG_ERROR_MCAST_LIST_SIZE
Message: NLB cluster [%2]: NLB failed to add a multicast MAC address to the network adapter it is bound to. This happened because the maximum number of multicast MAC addresses that can be assigned to this network adapter has been exhausted. Use a network adapter that supports more multicast MAC addresses or operate NLB in unicast mode.

Resolve

Change network adapter or operate NLB in unicast mode

Since the network adapter has reached the maximum number of multicast MAC addresses that can be assigned to it, you can either change the network adapter to one that supports more multicast MAC addresses, or use Network Load Balancing (NLB) Manager to change the NLB operation mode to unicast mode.

When you are using NLB Manager, 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 Manager 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 change the cluster operation mode to unicast:

  1. Click Start, click Administrative Tools, and then click Network Load Balancing Manager. You can also open NLB Manager by typing Nlbmgr at a command prompt..
  2. If NLB Manager does not already list the cluster, connect to the cluster.
  3. Right-click the cluster, and then click Cluster Properties.
  4. Click the Cluster Parameters tab, and specify Unicast in Cluster Operation Mode.

 

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 the network adapters are properly configured:

  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 members of the cluster.
  3. Type nlb.exe display, which displays details on the current cluster configuration and the IP configuration on the host operating system and the network adapter. Verify the configuration of the network adapter.

 

Network Adapter Functionality

NLB Cluster