The Network Load Balancing (NLB) driver on the host tracks connections to maintain client/network affinity configured on the NLB cluster. If the driver is not functioning properly, NLB may not be able to track TCP connections or may experience load distribution errors.
Resolutions
Address NLB connection tracking limits
The maximum number of active connections that Network Load Balancing (NLB) can track is reached. Although NLB will continue to accept new connections, it will not track the connection state until other connections are closed. This might result in breaking the affinity maintained by the driver during the connection.
To address the connection tracking limits, you can either add more hosts to the NLB cluster, which distributes the number of incoming connections across more cluster hosts, or increase the connection tracking limit.
Add a host to the NLB cluster
To add a host to the NLB cluster:
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.
Right-click the cluster where you want to add the host and choose Add Host To Cluster. If NLB Manager does not list the cluster, connect to the cluster.
Type the host's name and click Connect. The network adapters that are available on the host will be listed at the bottom of the dialog box.
Click the network adapter that you want to use for NLB, and then click Next. The IP address configured on this network adapter will be the dedicated IP address for this host.
Configure the remaining host parameters as appropriate, and then click Finish.
Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on your computer.
Increase the connection tracking limit by editing the registry key
To increase the connection tracking limit by editing the registry key:
Open Registry Editor.
Edit the value in the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\WLBS\Parameters\Interface\{GUID}\MaxDescriptorAllocs.
The GUID is the globally unique identifier of the network adapter that is experiencing the problem. This is the network adapter that is bound to NLB. If NLB is, or has been, bound to multiple network adapters, you can find the correct adapter by looking at the value for the ClusterIPAddress key for each GUID entry in the registry.
You should double the existing value of the registry key. After increasing the value, you must disable and re-enable the appropriate network adapter.
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