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.
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.
To change the cluster operation mode to unicast:
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..
If NLB Manager does not already list the cluster, connect to the cluster.
Right-click the cluster, and then click Cluster Properties.
Click the Cluster Parameters tab, and specify Unicast in Cluster Operation Mode.