Preparing to upgrade the Network Load Balancing cluster
Applies To: Windows Server 2008
Network Load Balancing (NLB) runs independently of other networking services provided by Windows Server 2008. On the other hand, the applications and roles/features running on the cluster can be dependent upon the network infrastructure and other network services in your existing environment. Prior to upgrading the existing cluster, deploy any network infrastructure components or networking services that are required by the applications and roles/features running on the cluster.
Before upgrading your NLB cluster, you should:
Verify that applications and roles/features running on the cluster are compatible with Windows Server 2008.
Upgrade the network infrastructure as required by the applications and roles/features running on the cluster.
Upgrade any networking services as required by the applications and roles/features running on the cluster.
Verifying Applications, Roles, and Features Are Compatible with Windows Server 2008
Before you upgrade the existing cluster, ensure that the applications and roles/features running on the cluster are compatible with Windows Server 2008. For help in determining if your application is compatible, use the Windows Application Compatibility Toolkit.
Upgrade necessary network infrastructure
Before you upgrade the existing cluster, ensure that the final configuration of the cluster can be supported by the network infrastructure that connects the cluster to client computers, to other servers within your organization, and to management consoles. Perform only the network infrastructure upgrades required by the applications and roles/features running on the cluster. Avoid performing upgrades to the network infrastructure for other reasons at the same time that you are upgrading the cluster. This minimizes the number of changes to the environment and reduces the likelihood of problems occurring during the upgrade process.
When performing this step, make sure to have specifications about your current network environment available for use. Specifically, your hardware and software inventory, and a map of network topology can be helpful.
The network infrastructure to upgrade includes the following components:
Upgrade any required networking services
NLB is independent of the other network services. As a result, no networking services upgrades are required for NLB. However, the applications and roles/features running on the cluster can be dependent on other networking services. For more information about requirements that the applications and roles/features running on the cluster might have for upgrading networking services, see Networking.
Considerations when planning an upgrade
During an upgrade, an NLB cluster will simultaneously have Windows Server 2003 and Windows Server 2008 cluster nodes in the same cluster. This mixed mode setup is supported only when the upgrade installation is in progress and should not be used for an extended period of time in deployment. After the entire NLB cluster has been upgraded to Windows Server 2008, you can use new NLB features, such as IPv6 and support for multiple dedicated IP addresses. If you have both Windows Server 2003 and Windows Server 2008 cluster nodes, you cannot use the new NLB Windows Server 2008 features.
In Windows Server 2003, NLB does not have IPv6 support. You should only add IPv6 dedicated IP addresses to the NLB cluster after all nodes have been upgraded to Windows Server 2008. You should use a separate cluster when testing IPv6.
Make sure you run the drainstop command on each node you plan to upgrade before you start the upgrade process, and then set the node's initial host state to Stopped. After the upgrade process is complete, you should verify that the application that is load balanced is working properly with the dedicated IP address. You can then change the initial host state back and start NLB on that node.
If the NLB cluster you plan to upgrade is in the unicast mode of operation, inter-host communication is enabled by default in Windows Server 2008. Inter-host communication allows NLB cluster hosts to communicate with each other when the cluster is in the unicast mode. In Windows Server 2003, inter-host communication is disabled by default. Before starting a rolling upgrade from Windows Server 2003 to Windows Server 2008, you should enable inter-host communication on all cluster hosts. For more information, see the Microsoft Support article on this subject.
After the upgrade is complete on a cluster host, you should verify that the applications work properly before adding the upgraded host to the NLB cluster. Test the load balanced application on each host upgraded to Windows Server 2008 before adding it to the NLB cluster. The test can be performed against one of the computer's automatically configured IP addresses.
After a Windows Server 2003 node is upgraded and added back to the NLB cluster or a new Windows Server 2008 node is added to a cluster, use Network Load Balancing (NLB) Manager on the Windows Server 2008 node to manage the cluster. You should not attempt to manage the cluster using NLB Manager from a Windows Server 2003 node since it will not be able to manage Windows Server 2008 nodes. A cluster that has at least one Windows Server 2008 node should only be managed from a computer running either Windows Server 2008 or Windows Vista® using Remote Server Management Tools (RSAT).