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 the IP address for the computer name is different from the IP address(es) for the websites 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 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 the IP address using the Network icon in the Control Panel. The Network icon is also commonly referred to as your network interface card (NIC).

You must also ensure that the websites' static IP addresses that reside on the web server on this computer are removed from the IP stack (also with the Network icon in the Control Panel). Typically, someone added the website IP addresses to the server's IP stack before installing ClusterCATS and creating clusters. You must manually remove those IP addresses so 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:

Change the IP address and FQHN of the website
Change the address and FQHN of the web server's computer

Because most webmasters cannot change the website address, the instructions in this section explain how to change the computer or machine name.

Note: Computer names associated with the ClusterCATS dynamic IP addresses must have fully qualified host names (FQHNs) in DNS and DNS forward and reverse entries.

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

Set up your servers with maintenance addresses. See "Setting up maintenance IP addresses".
Install ClusterCATS. See "Installing ClusterCATS on Windows".
Enable ClusterCATS dynamic IP addressing. See "Enabling ClusterCATS dynamic IP addressing".
Create your clusters. See "Creating clusters in Windows".

Benefits of ClusterCATS dynamic IP addressing

There are several benefits to your 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, see "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, see "Setting up maintenance IP addresses".
Optimizing Server failover - on Windows systems, when ClusterCATS is configured using static IP addresses, IP address conflicts 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 restarts. ClusterCATS dynamic IP addressing prevents this double-restart.

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 a web server, virtual server, or website. This 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 lets ClusterCATS communicate with the server in case of a web server failure.

Note: You must have at least two IP addresses available for a computer in order to use one for a maintenance IP address.

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

Note: This procedure must be performed on each system in the cluster and must be done before installing ClusterCATS.

To set up a maintenance address before installing ClusterCATS:

Back up your system files.
Obtain a new IP address and new computer name. Be sure to configure your DNS so your new address has both forward and reverse DNS entries.
For IIS 4.0 and 5.0: Uninstall products that are configured as part of IIS, including JRun.
For IIS 4.0: Uninstall the Windows NT 4.0 Option Pack (which includes IIS) by selecting Start > Settings > Control Panel > Add/Remove Programs. Restart the server.
For IIS 5.0 or NES: Skip this step.
Open the Advanced IP Addressing dialog box by right-clicking Network Neighborhood. Select Properties. On the Protocols tab, select TCP/IP Protocol and click Properties and then click Advanced.
Select the computer'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.
Click OK, and OK again and click the Identification tab. Click Change.
Enter a new name for the computer in the Computer Name field. The 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.macromedia.com is a possible FQHN. The first portion of this FQHN (support1) can be a NetBIOS name. Note that 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 macromedia.com. The Domain field on the Identification tab is different; it has nothing to do with DNS but only corresponds to your NT domain.
Close all open dialog boxes and restart the server.
For IIS 4.0: Reinstall the NT 4.0 Option Pack and then restart the server.
For IIS 5.0 or NES: Skip this step.
For IIS 4.0: You may need to reconfigure your websites using the Internet Service Manager.
For IIS 5.0 or NES: Skip this step.
Reinstall products that are configured as part of IIS, including JRun/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.
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 set up a maintenance IP address for each web server in the cluster, as described in "Setting up maintenance IP addresses", and bound any websites to the appropriate IP addresses. The maintenance IP address must be different from the IP address associated with the website.

This section instructs you to create the cluster while the website is still bound to the IP address. When creating a cluster, you should not specify the maintenance address. When you test the cluster, you can remove the websites from the IP addresses and restart. ClusterCATS creates the address dynamically when the server restarts.

To enable dynamic addressing:

Verify that you can access your server by its maintenance address. If not, assign one to the server using the procedure described in "Setting up maintenance IP addresses".
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 by the Network Control Panel. If the addresses are not configured, the Netscape Enterprise Server will fail to start. In order for failover to work properly, the primary web server cannot 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 website on the web server in the MMC. If IP addresses are not assigned to your web server yet, assign them now. 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.
Restart your server to apply these changes.
Create a cluster using the Cluster Setup Wizard.
Note: Do not specify a maintenance address when adding cluster members. Because the IP addresses for the cluster members are still bound to their NICs, there is no need to do this. For more information, see "Creating clusters with the Cluster Setup Wizard".
Verify that your cluster is functioning properly.
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. Click Advanced.
Unbind the IP addresses from the web server's NIC by selecting each IP address in the IP Addresses region and clicking Remove. This step removes the IP addresses corresponding to the website.
Click OK, three times.
Restart all the systems in the cluster.
ClusterCATS assigns the IP addresses dynamically to your web servers.

Using ClusterCATS
Optimizing ClusterCATS