Citrix Systems 9.2 manual Advanced Policy Evaluation Across Features, Entries in a Policy Bank

Chapter 2 Configuring Advanced Policies 19

balancing virtual servers, the NetScaler process the response-time policies for content switching virtual servers.

8.Response-time default. If policy evaluation cannot be completed after all response-time, virtual-server-specific policies have been evaluated, the NetScaler processes response-time default policies.

Advanced Policy Evaluation Across Features

In addition to attending to evaluation of policies within a feature, if you have bound policies to a content switching virtual server, note that these policies are evaluated before other policies. Binding a policy to a content switching vserver produces a different result in NetScaler versions 9.0.x and later than in 8.x versions. In NetScaler 9.0 and later versions, evaluation occurs as follows:

•Content switching policies are evaluated before other policies. If a content switching policy evaluates to TRUE, the target load balancing vserver is selected.

•If all content switching policies evaluate to FALSE, the default load balancing vserver under the content switching VIP is selected.

After a target load balancing vserver is selected by the content switching process, policies are evaluated in the following order:

1.Policies that are bound to the global override bind point.

2.Policies that are bound to the default load balancing vserver.

3.Policies that are bound to the target content switching vserver.

4.Policies that are bound to the global default bind point.

To be sure that the policies are evaluated in the intended order, follow these guidelines:

•Make sure that the default load balancing vserver is not directly reachable from the outside; for example, the vserver IP address can be 0.0.0.0.

•To prevent exposing internal data on the load balancing default vserver, configure a policy to respond with a “503 Service Unavailable” status and bind it to the default load balancing vserver.

Entries in a Policy Bank

Each entry in a policy bank has, at minimum, a policy and a priority level. You can also configure entries that change the priority-based evaluation order, and you can configure entries that invoke external policy banks.