Configuring a loopback adapter for load balancing in a Gateway cluster

When you deploy IBM® Load Balancer in front of two or more IBM WebSphere® proxy servers, client requests are directed to Load Balancer using its cluster IP address. Each of the proxy servers must have a loopback address using the same IP address, so they can accept unmodified packets from the Load Balancer server.

The following instructions explain how to configure a loopback adapter in Microsoft Windows 2003 (the user interface may vary depending on your operating system).

1. Click Start, then click Control Panel.
2. If you have not done so already, add the MS Loopback Adapter Driver.
3. Click Add Hardware. This launches the Add Hardware Wizard.
4. Click Next.
5. Select Yes, I have already connected the hardware, then click Next.
6. If the MS Loopback Adapter is in the list, it is already installed. Click Cancel to exit.
7. If the MS Loopback Adapter is not in the list, select Add a New Device and click Next.
8. To select the hardware from a list, for the Find New Hardware panel, click No and then click Next.
9. Select Network Adapters and clickNext.
10. On the Select Network Adapter panel, select Microsoft in the Manufacturers list, then select Microsoft Loopback Adapter.
11. Click Next, then click Next again to install the default settings.
12. Click Finish to complete installation.
13. From the Control Panel, double-click Network and Dial-up Connections.
14. Select device name: Microsoft Loopback Adapter.
15. Select Properties from the drop-down menu.
16. Select Internet Protocol (TCP/IP), then click Properties.
17. Select Use the following IP address.
18. In the IP address field, enter the IP address of the cluster address.
19. In the Subnet mask field, enter the subnet mask of the back-end server.
20. For the default DNS server, do not enter a router address. Use the local host as the default DNS server.
21. Save your changes.
22. Ensure that the Loopback Adapter is listed in the correct order in the list of network adapters. From the Control Panel, double-click Network and Dial-up Connections.
23. In the Connections box on the Adapters and Bindings tab, make sure Loopback Adapter is listed after the Local Area Connection. Move Loopback adapter if the order is not correct. It is essential that the physical IP address appears as the first entry in the list, instead of the virtual, Loopback Adapter IP address. Change the order if required.
24. Restart the WebSphere proxy server.
25. Repeat this task for every WebSphere proxy server used by the cluster.