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
An entire compound condition may be enclosed in parentheses:
(med eq 42 and next-hop in (10.0.2.2))
The parentheses may serve to make the grouping of subconditions more readable, or they may force the
evaluation of a subcondition as a unit.
In the following example, the highest-precedence not operator applies only to the destination test, the and
operator combines the result of the not expression with the community test, and the or operator combines
that result with the MED test.
med eq 10 or not destination in (10.1.3.0/24) and community matches-any ([12..34]:[56..78])
With a set of parentheses to express the precedence, the result is the following:
med eq 10 or ((not destination in (10.1.3.0/24)) and community matches-any
([12..34]:[56..78])
The following is another example of a complex expression:
(origin is igp or origin is incomplete or not med eq 42) and next-hop in (10.0.2.2)
The left conjunction is a compound condition enclosed in parentheses. The first simple condition of the inner
compound condition tests the value of the origin attribute; if it is Interior Gateway Protocol (IGP), then the
inner compound condition is true. Otherwise, the evaluation moves on to test the value of the origin attribute
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
490 OL-30423-03
Implementing Routing Policy
Policy Statements
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