17.1 Setting Up a Group of Web Servers

You can configure a proxy service to service a “virtual” group of Web servers, which adds load balancing and redundancy. Each Web server in the group must contain the same material. When you create the proxy service, you set up the first server by specifying the URLs you want users to access and the rights the users need for each URL. When you add additional Web servers to the proxy service, these servers automatically inherit everything you have configured for the first Web server.

Figure 17-2 Adding Redundant Web servers

For this configuration, you use a single reverse proxy and proxy service. To add multiple Web servers to a host:

  1. In the Administration Console, click Access Manager > Access Gateways > Edit > [Name of Reverse Proxy] > [Name of Proxy Service] > Web Servers.

  2. In the Web Server List section, click New.

  3. Specify the IP address or the fully qualified DNS name of another Web server for the “virtual” group, then click OK.

  4. Repeat Steps 2 and 3 to add additional Web servers to the group.

  5. To save your changes to browser cache, click OK.

  6. To apply the changes, click the Access Gateways link, then click Update > OK.

The NetWare Access Gateway performs a round robin among the Web servers, dividing the load among them. The Linux Access Gateway can perform a round robin, or it can be configured to perform a simple failover, sending all the traffic to the first Web server as long as it is available. Traffic is sent to another Web server in the list only when the first Web server is no longer available. To configure this option, see Section 13.6.2, Configuring TCP Connect Options for Web Servers.

Connection persistence is enabled by default. This allows the Access Gateway to send multiple HTTP requests to the Web server to be serviced before the connection is closed. To configure this option, see Section 13.6.2, Configuring TCP Connect Options for Web Servers.

Session persistence is enabled whenever a second Web server is added to the list. This allows a browser to persistently use the same Web server after an initial connection has been established. This type of persistence is not configurable. For more information on persistent connections, see Section 13.6.3, Configuring Connection and Session Persistence.