Virtual clusters

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Virtual clusters

You create a virtual cluster by configuring multiple virtual IP addresses (where each IP address typically corresponds to different Web sites or applications hosted on the cluster) on a single network adapter and then configuring different port rules for each virtual IP address. In this way, on each host you are able to have IP address-specific:

• Port Range

• Protocols

• Affinity

• Load weight

• Filtering mode

By using a load weight of zero for specific virtual IP addresses, you can also define a virtual cluster that limits applications, Web sites, or virtual IP addresses to a specific subset of hosts within your Network Load Balancing (NLB) cluster. See the diagram below for an example of this use of virtual clusters.

This diagram depicts a four host Network Load Balancing cluster. Through the use of virtual clusters defined by IP address-specific load weights, Network Load Balancing directs network traffic as follows:

• Users accessing Web Site A (IP address nnn.nnn.nnn.1) are directed to any of the four hosts

• Users accessing Web site B (IP address nnn.nnn.nnn.2), which is a virtual cluster, are directed to hosts 1 and 2

• Users accessing Web site C (IP address nnn.nnn.nnn.3), which is a virtual cluster, are directed to hosts 3 and 4

This is accomplished by setting the load weights as follows:

• Load weight = 0 on hosts 3 and 4 for IP address xxx.xxx.xxx.2

• Load weight = 0 on hosts 1 and 2 for IP address xxx.xxx.xxx.3.

Be aware that to use virtual clusters, all hosts in the cluster must be running one of the Windows Server 2003 family of products.

For more information on creating port rules, see Create a new port rule.