Policy Framework Configuration Guide - Juniper Networks

Chapter 4: Routing Policy Configuration
Table 14: Policy Expression Logical Operators (continued)
Logical Operator
Policy Expression Logic
How Logical Operator Affects Policy Expression
Evaluation
! (Logical NOT)
Logical NOT reverses value of TRUE to
FALSE and of FALSE to TRUE. It also
reverses the actions of accept and next
policy to reject, and reject to accept.
If used with the logical AND operator and the first routing
policy value of FALSE is reversed to TRUE, the next policy is
evaluated. If the value of TRUE is reversed to FALSE, the
evaluation of the expression ends and subsequent policies in
the expression are not evaluated.
If used with the logical OR operator and the first routing policy
value of FALSE is reversed to TRUE, the evaluation of the
expression ends and subsequent policies in the expression
are not evaluated. If the value of TRUE is reversed to FALSE,
the next policy is evaluated.
If used with a policy and the flow control action is accept or
next policy, these actions are reversed to reject. If the flow
control action is reject, this action is reversed to accept.
For more information, see the following sections:
• Policy Expression Examples on page 61
• How a Policy Expression Is Evaluated on page 62
• Example: Evaluating Policy Expressions on page 63
Policy Expression Examples
The following examples show how to use the logical operators to create policy
expressions:
• Logical AND—In the following example, policy1 is evaluated first. If after policy1 is
evaluated, a value of TRUE is returned, policy2 is evaluated. If a value of FALSE is
returned, policy2 is not evaluated.
export (policy1 && policy2)
• Logical OR—In the following example, policy1 is evaluated first. If after policy1 is
evaluated, a value of TRUE is returned, policy2 is not evaluated. If a value of FALSE is
returned, policy2 is evaluated.
export (policy1 || policy2)
• Logical OR and logical AND—In the following example, policy1 is evaluated first. If after
policy1 is evaluated, a value of TRUE is returned, policy2 is skipped and policy3 is
evaluated. If after policy1 is evaluated, a value of FALSE is returned, policy2 is evaluated.
If policy2 returns a value of TRUE, policy3 is evaluated. If policy2 returns a value of
FALSE, policy3 is not evaluated.
export [(policy1 || policy2) && policy3]
• Logical NOT—In the following example, policy1 is evaluated first. If after policy1 is
evaluated, a value of TRUE is returned, the value is reversed to FALSE and policy2 is
not evaluated. If a value of FALSE is returned, the value is reversed to TRUE and policy2
is evaluated.
Copyright © 2010, Juniper Networks, Inc.
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