Citrix Systems 9.2 Evaluation Order Within a Policy Bank

20 Citrix NetScaler Policy Configuration and Reference Guide
The following table summarizes each entry in a policy bank.
If the policy evaluates to TRUE, the NetScaler stores the action that is associated
with the policy. If the policy evaluates to FALSE, the NetScaler eva luates the next
policy. If the policy is neither TRUE nor FALSE, the NetScaler uses the
associated Undef (undefined) action.
Evaluation Order Within a Policy Bank
Within a policy bank, the evaluation order depends on the following items:
•A priority. The most minimal amount of information about evaluation
order is a numeric priority level. The lower the number, the higher the
priority.
•A Goto expression. If supplied, the Goto expression indicates the next
policy to be evaluated, typically within the same policy bank.. Goto
expressions can only proceed forward in a bank. To prevent looping, a
policy bank configuration is not valid if a Goto statement points backwards
in the bank.
•Invocation of other policy banks. Any entry can invoke an external policy
bank. The NetScaler provides a built-in entity named NOPOLICY that does
not have a rule. You can add a NOPOLICY entry in a policy bank when you
want to invoke another policy bank, but do not want to process any other
rules prior to the invocation. You can have multiple NOPOLICY entries in
multiple policy banks.
Values for a Goto expression are as follows:
Format of Each Entry in a Policy Bank
Policy Name Priority Goto
Expression Invocation Type Policy Bank to be Invoked
The policy name, or a
“dummy” policy
named NOPOLICY.
The NOPOLICY
entry controls
evaluation flow
without processing a
rule. For more
information, see
“Evaluation Order
Within a Policy
Bank,” on page 20.
An integer. Optional.
Identifies the
next policy in
the bank to
evaluate, or
ends any
further
evaluation.
Optional.
Indicates that
an external
policy bank
will be
invoked.
This field
restricts the
choices to a
global policy
label or a
virtual server.
Optional.
Used with
Invocation
Type. This is
the label for a
policy bank or
a virtual server
name.
The NetScaler
returns to the
current bank
after
processing the
external bank.