Policy Framework Configuration Guide - Juniper Networks

Chapter 4: Routing Policy Configuration
To modify the preceding routing policy so that an IGP does not export unwanted routes,
you can specify the following additional terms:
[edit]
routing-options {
autonomous-system 56;
}
protocols {
isis {
export statics-policy;
}
}
policy-options {
policy-statement statics-policy {
term term1 {
from {
route-filter 192.168.0.0/16 orlonger;
route-filter 172.16.1.1/3 orlonger;
}
then reject; # reject the prefixes in the route list
}
term term2 { # reject direct routes
from protocol direct;
then reject;
}
term term3 { # reject static routes
from protocol static;
then reject;
}
term term4 { # reject local routes
from protocol local;
then reject;
}
term term5 { # reject aggregate routes
from protocol aggregate;
then reject;
}
term term6 {
then accept; # accept all other routes
}
}
}
Applying Policy Expressions to Routes Exported from Routing Tables
Policy expressions give the policy framework software a different way to evaluate routing
policies. A policy expression uses Boolean logical operators with policies. The logical
operators establish rules by which the policies are evaluated.
During evaluation of a routing policy in a policy expression, the policy action of accept,
reject, or next policy is converted to the value of TRUE or FALSE. This value is then
evaluated against the specified logical operator to produce output of either TRUE or
FALSE. The output is then converted back to a flow control action of accept, reject, or
next policy. The result of the policy expression is applied as it would be applied to a single
Copyright © 2010, Juniper Networks, Inc.
59