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Windows Server 2008 - NLB Enhancements

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Over the past few weeks, a number of customers have asked me about where we are going with NLB in Windows Server 2008 (aka Longhorn). Below is a summary of the key changes you'll see when the new server OS is released:

  • Support for IPv6. NLB fully supports IPv6 for all communication. All NLB components support IPv6 addresses, and the addresses can be configured as the primary cluster IP address, the dedicated IP addresses, and the virtual IP addresses. In addition, IPv6 can be load balanced as native IPv6 and in the IPv6 over IPv4 modes. 
  • Support for NDIS 6.0. The NLB driver uses the NDIS 6.0 lightweight filter model. NDIS 6.0 retains backward compatibility with earlier NDIS versions. The design of NDIS 6.0 includes enhanced driver performance and scalability and a simplified NDIS driver model. 
  • WMI enhancements. The MicrosoftNLB namespace adds multiple dedicated IP address support for IPv6, which include: 
    • Classes in the MicrosoftNLB namespace support IPv6 addresses (in addition to IPv4 addresses). 
    • The MicrosoftNLB_NodeSetting class supports multiple dedicated IP addresses by specifying them in DedicatedIPAddresses and DedicatedNetMasks. 
  • Improved denial of service (DoS) attack and timer starvation protection. Using a callback interface, NLB can detect and notify applications during an attack or when a node is under excessive load. ISA Server uses this functionality in scenarios where the cluster node is overloaded or is being attacked.
  • Support for multiple dedicated IP addresses per node. NLB fully supports defining more than one dedicated IP address per node. Previously only one dedicated IP address per node was supported. This functionality is used by ISA Server to manage each NLB node for scenarios where clients consist of both IPv4 and IPv6 traffic. 
  • Support for rolling upgrades. NLB supports rolling upgrades from Windows Server 2003 to Windows Server "Longhorn". For deployment information for NLB, including information on rolling upgrades, see https://go.microsoft.com/fwlink/?LinkId=87253. 
  • Consolidated management through Network Load Balancing Manager. Using the Network Connections tool is no longer required to configure NLB clusters—NLB cluster configuration is performed solely through NLB Manager in Windows Server "Longhorn". This minimizes possible NLB configuration issues that are caused by inconsistencies in settings across cluster hosts.
  • Addressing of potential unicast interhost communication issues (described in https://support.microsoft.com/kb/898867).