Clustering the Web Servers

  • Article

To increase availability and scalability for your Commerce Server applications, you can cluster the Web servers using a variety of load balancing solutions including hardware load balancing devices or Microsoft Windows 2000 Network Load Balancing (NLB). This section focuses on using NLB to cluster the Web servers. For more information about clustering, see Clustering Concepts.

In a Web cluster using NLB, each member typically has two network adapters: a front-end adapter to handle client requests and a back-end adapter for internal communications (such as cluster operations and access to databases). All members share a cluster IP address, or virtual IP (VIP) address. Optionally, each member has a dedicated IP (DIP) address.

The following figure illustrates the IP addresses for a sample NLB configuration.

IP addresses for sample NLB configuration

All members on a single subnet concurrently detect all incoming requests for the cluster's VIP. NLB uses a fully distributed algorithm to determine which member should handle the request. All other members will discard the request.

NLB automatically detects changes in a cluster's state (members being set offline, online, added, or removed) by transmitting an NLB exchange message over the front-end adapters. Changes in a cluster's state cause inconsistencies with these message exchanges. If these inconsistencies endure beyond a configurable amount of time (one second by default), NLB initiates a process to determine the current state of the cluster so that it can load balance the cluster properly. NLB automatically redistributes requests among the active, remaining members. This process ensures that only active members receive requests.

You can install NLB by using any of the following programs:

  • Microsoft Application Center 2000
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Datacenter Server

To install NLB

  1. Click Start, point to Settings, and then click Network and Dial-up Connections.
  2. Right-click the Local Area Connection on which NLB is to be installed, and then click Properties.
  3. In the Local Area Connection Properties dialog box, under Components checked are used by this connection, check the Network Load Balancing check box, and then click the Properties button.
  4. In the Network Load Balancing Properties dialog box, for Primary IP address, enter the cluster IP address, or virtual IP (VIP) address. This is the IP address that is shared by all members of the cluster.
  5. Enter the corresponding Subnet mask, and then click OK.
  6. To complete NLB installation, click OK.
  7. Repeat this procedure on each member of the NLB cluster.

Configuring NLB

The following procedure describes how to configure NLB on the Web tier for a typical deployment.

To configure NLB on the Web tier

  1. Open properties for the front-end adapter (for communicating with clients on the Internet).
  2. In Network Load Balancing Properties dialog box, on the Cluster Parameters tab, type the Primary IP address (the virtual IP address shared across all cluster members), Subnet Mask, and Full Internet name.
  3. In Network Load Balancing Properties dialog box, on the Host Parameters tab, type the Priority (Unique host ID), Dedicated IP address, and Subnet Mask.
  4. In Network Load Balancing Properties dialog box, on the Port Rules tab, remove the default port rule covering ports 0 to 65535 by selecting the port rule, then clicking Remove.
  5. Create a port rule for HTTP using the information in the following table, and then click Add.
    Field Enter
    Port range 80 to 80
    Protocols Both
    Affinity None
  6. Create a port rule for HTTPS using the information in the following table, and then click Add.
    Field Enter
    Port range 443 to 443
    Protocols Both
    Affinity Single
  7. In Internet Protocol (TCP/IP) Properties dialog box, click Advanced.
  8. In the Advanced TCP/IP Settings dialog box, on the IP Settings tab, in the IP addresses section, click Add, and then type the IP address (the virtual IP address shared across all members) and Subnet mask of the cluster.
  9. Restart the server.
  10. Repeat steps 1-9 for each Web server using a different dedicated IP address. For each subsequent Web server that you add to the cluster, increment the Priority (Unique host ID) value by one.

See Also

Connecting the Web Servers

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