Advanced ColdFusion Administration
Optimizing ClusterCATS

ClusterCATS Dynamic IP Addressing (Windows only)

This section describes how to enable ClusterCATS dynamic IP addressing on your site. You do not have to configure your system on UNIX for dynamic IP addressing because it is set up by default.

If your site is already configured so that the IP address for the computer name is different from the IP address(es) for the Web sites configured on this server, you can skip "Setting up maintenance IP addresses" and continue with "Enabling ClusterCATS dynamic IP addressing".

Understanding static and dynamic IP address configurations

Each server that you add to a cluster must have an IP address defined for it. Because the Internet operates on a TCP/IP network protocol for sending and receiving packets of data to and from networked computers, you must correctly define your servers' IP addresses so that they can send and receive network data as intended.

The static address must be assigned to the server itself-the physical box. You do so by making an entry in the server's IP stack. On Windows servers, you add this IP address using the Network icon in the Control Panel.

In addition to assigning the server's static address, you must make sure that the Web sites' static IP addresses that reside on the Web server on this machine get removed from the IP stack (also via the Network icon in the Control Panel). Typically, you or someone else added the Web site IP addresses to the server's IP stack before installing ClusterCATS and creating clusters. You must now manually remove those IP addresses so that ClusterCATS can dynamically create them in the IP stack according to server load and availability in the cluster.

There are generally two ways to move from static to dynamic addressing; one way is to change the IP address and FQHN of the Web site, and the other method is to change the address and FQHN of the Web server's machine. Since most Webmasters cannot change the web site address, the instructions in this section explain how to change the computer or machine name.

The general process for configuring ClusterCATS with dynamic IP addressing is as follows:

1. Set up your servers with maintenance addresses. Refer to "Setting up maintenance IP addresses".
2. Install ClusterCATS.
3. Enable ClusterCATS dynamic IP addressing. Refer to "Enabling ClusterCATS dynamic IP addressing".
4. Create your clusters. "Creating clusters in Windows".

Benefits of ClusterCATS dynamic IP addressing

There are several benefits to using ClusterCATS dynamic IP addressing:

• Using Maintenance mode. With dynamic IP addressing, cluster members put into Maintenance mode on Windows clusters will fail over to another server and then gracefully return when brought out of Maintenance mode. For more information on Maintenance mode, refer to "Using Maintenance Mode (Windows only)".
• Using maintenance IP addresses. If you use ClusterCATS dynamic IP addressing, you can remotely access servers in your cluster if they fail or become unavailable through the maintenance address. Maintenance addresses are statically bound to the server during the setup for ClusterCATS dynamic IP addressing. For more information on using maintenance addresses, refer to "Setting up maintenance IP addresses".
• Optimizing Server failover. On Windows systems, when ClusterCATS is configured using static IP addresses, IP address conflicts will occur when the failed server recovers from a failover and tries to re-claim its IP address. This IP conflict is cleared when the failed server automatically reboots. ClusterCATS Dynamic IP Addressing prevents this double-reboot.

Setting up maintenance IP addresses

Setting up a maintenance IP address ensures that you have one static IP address on the system that is not assigned to any Web server, virtual server, or Web site. This static address, often referred to as the system's "maintenance address," provides administrators with a consistent way to access the system remotely at all times. It also allows ClusterCATS to be able to communicate with the server in the event of a Web server failure.

This section shows you how to add a maintenance address that will support ClusterCATS dynamic IP addressing. If your server has only one static address that corresponds to both the computer name and the Web site, you must reconfigure it to allow for a maintenance address.

To set up a maintenance address prior to installing ClusterCATS:

1. Back up your system files.
2. Obtain a new IP address and new computer name. Be sure to configure your DNS so that your new address has both forward and reverse DNS entries.
3. For IIS 4.0 and 5.0: Uninstall any products which are configured as part of IIS, including Allaire ColdFusion.
4. For IIS 4.0: Uninstall the Windows NT 4.0 Option Pack (which includes IIS) by selecting Start > Settings > Control Panel > Add/Remove Programs and reboot the server.

   For IIS 5.0 or NES: Skip this step.

5. Open the Advanced IP Addressing dialog box by right-clicking Network Neighborhood and select Properties. On the Protocols tab, select TCP/IP Protocol and click Properties and then click Advanced.

   

6. Select the machine's primary NIC in the Adapter field. Add the new IP address in the IP Addresses region. You will use this address as the maintenance address and machine address. Make a note of all IP addresses on the NIC.
7. Click OK and OK again and select the Identification tab. Click Change.
8. Enter a new name for the computer in the Computer Name field. This name corresponds to the new IP address that you just added. Do not change the Domain field on this tab.
   

   Note The Computer Name on the Identification tab should only be a NetBIOS name, not a fully-qualified host name (FQHN). For example, support1.allaire.com is a possible FQHN. The first portion of this FQHN (support1) can be a NetBIOS name. support1 would also appear as the host name under the DNS tab in Protocols. The domain under the DNS tab in this case would be allaire.com. The Domain field on the Identification tab is different; it has nothing to do with DNS but only corresponds to your NT domain.

   
   
9. Close all open dialog boxes and restart the server.
10. For IIS 4.0: Reinstall the NT 4.0 Option Pack and then reboot your server.

    For IIS 5.0 or NES: Skip this step.

11. For IIS 4.0: You may need to reconfigure your web sites using the Internet Service Manager.

    For IIS 5.0 or NES: Skip this step.

12. Reinstall any products which are configured as part of IIS, including ColdFusion and ClusterCATS. This should include any products you uninstalled in step 3.

    When you install ClusterCATS, you must select the "Server Failover" option during the installation procedure.

    
    

    Note Do not create any clusters at this time.

    
    
13. Enable the ClusterCATS dynamic IP addressing scheme using the procedure described in "Enabling ClusterCATS dynamic IP addressing".

Enabling ClusterCATS dynamic IP addressing

Before enabling the ClusterCATS dynamic IP addressing, you must have already set up a maintenance IP address for each Web server in the cluster as described in "Setting up maintenance IP addresses" and bound any Web sites to the appropriate IP addresses. The maintenance IP address must be different from the IP address associated with the Web site.

This section instructs you to create the cluster while the Web site is still bound to the IP address. When creating a cluster, you should not specify the maintenance address. Once you test the cluster, you can then remove the IP addresses from the Web sites and reboot. ClusterCATS then creates the address dynamically when the server boots up.

To enable dynamic addressing:

1. Verify that you can access your server via its maintenance address. If not, assign one to the server using the procedure described in "Setting up maintenance IP addresses".
2. Configure your Web server to support ClusterCATS dynamic IP addressing.

   For Netscape Enterprise Server: Verify that the IP addresses associated with the primary Web Server and Hardware Virtual Servers are configured on your system via the Network Control Panel. If these addresses are not configured on the system, the Netscape Enterprise Server will fail to start. In order for failover to work properly, the primary Web server can not be bound to a specific IP address. If it is, remove the binding using the Netscape Administrative Server.

   For IIS: Verify that you have a unique IP address (or addresses) assigned to each Web site on the Web server in the MMC. If IP addresses are not assigned to your Web server yet, assign them now. Note that with IIS 4.0, you may have to manually enter the IP address if it does not appear in the drop down list on the Web Site properties tab.

3. Reboot your server to apply these changes.
4. Create a cluster using the Cluster Setup Wizard.
   

   Note Do not specify a maintenance address when adding cluster members. Since the IP addresses for the cluster members are still bound to their NICs, there is no need to do this. For more information about creating clusters, refer to "Creating clusters with the Cluster Setup Wizard".

   
   
5. Verify that your cluster is functioning properly.
6. Open the Advanced IP Addressing dialog box by right-clicking Network Neighborhood and select Properties. On the Protocols tab, select TCP/IP Protocol and click Properties and then click Advanced.

   

7. Unbind the IP addresses from the Web server's NIC by selecting each IP address in the IP Addresses region and clicking Remove. This removes the IP addresses corresponding to the Web Site.
8. Click OK three times.
9. Simultaneously reboot all the systems in the cluster. Note that you do not want to eboot them one at a time or they will failover.

   ClusterCATS assigns the IP addresses dynamically to your Web servers.

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