Boolean Conditions - Cisco ASR 9000 Series Routing Configuration Manual

Policy Statements
else
set local-preference 0
endif
The statements within an if statement may themselves be if statements, as shown in the following example:
if community matches-any (12:34,56:78) then
if med eq 150 then
drop
endif
set local-preference 100
endif
This policy example sets the value of the local preference attribute to 100 on any route that has a community
value of 12:34 or 56:78 associated with it. However, if any of these routes has a MED value of 150, then these
routes with either the community value of 12:34 or 56:78 and a MED of 150 are dropped.

Boolean Conditions

In the previous section describing the if statement, all of the examples use simple Boolean conditions that
evaluate to either true or false. RPL also provides a way to build compound conditions from simple conditions
by means of Boolean operators.
Three Boolean operators exist: negation (not), conjunction (and), and disjunction (or). In the policy language,
negation has the highest precedence, followed by conjunction, and then by disjunction. Parentheses may be
used to group compound conditions to override precedence or to improve readability.
The following simple condition:
med eq 42
is true only if the value of the MED in the route is 42, otherwise it is false.
A simple condition may also be negated using the not operator:
not next-hop in (10.0.2.2)
Any Boolean condition enclosed in parentheses is itself a Boolean condition:
(destination in prefix-list-1)
A compound condition takes either of two forms. It can be a simple expression followed by the and operator,
itself followed by a simple condition:
med eq 42 and next-hop in (10.0.2.2)
A compound condition may also be a simpler expression followed by the or operator and then another simple
condition:
origin is igp or origin is incomplete
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
566
Implementing Routing Policy