pass
drop
pass
end-policy
When one policy applies another, it is as if the applied policy were copied into the right place in the applying
policy, and then the same drop-and-pass semantics are put into effect. For example, policies ONE and TWO
are equivalent to policy ONE-PRIME:
route-policy ONE
apply two
if as-path neighbor-is '123' then
pass
endif
end-policy
route-policy TWO
if destination in (10.0.0.0/16 le 32) then
drop
endif
end-policy
route-policy ONE-PRIME
if destination in (10.0.0.0/16 le 32) then
drop
endif
if as-path neighbor-is '123' then
pass
endif
end-policy
Because the effect of an explicit drop statement is immediate, routes in 10.0.0.0/16 le 32 are dropped without
any further policy processing. Other routes are then considered to see if they were advertised by autonomous
system 123. If they were advertised, they are passed; otherwise, they are implicitly dropped at the end of all
policy processing.
The done statement indicates that the action to take is to stop executing the policy and accept the route. When
encountering a done statement, the route is passed and no further policy statements are executed. All
modifications made to the route prior to the done statement are still valid.
Action
An action is a sequence of primitive operations that modify a route. Most actions, but not all, are distinguished
by the set keyword. In a route policy, actions can be grouped together. For example, the following is a route
policy comprising three actions:
route-policy actions
set med 217
set community (12:34) additive
delete community in (12:56)
end-policy
If
In its simplest form, an if statement uses a conditional expression to decide which actions or dispositions
should be taken for the given route. For example:
if as-path in as-path-set-1 then
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
488 OL-30423-03
Implementing Routing Policy
Policy Statements
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