Policy Framework Configuration Guide - Juniper Networks

Junos 10.4 Policy Framework Configuration Guide
The following sections discuss the following tasks for configuring AS path regular
expressions and provides the following examples:
• Configuring AS Path Regular Expressions on page 96
• How AS Path Regular Expressions Are Evaluated on page 101
• Examples: Configuring AS Path Regular Expressions on page 101
Configuring AS Path Regular Expressions
You can create a named AS path regular expression and then include it in a routing policy
with the as-path match condition (described in “Configuring Match Conditions in Routing
Policy Terms” on page 41). To create a named AS path regular expression, include the
as-path statement:
as-path name regular-expression;
You can include this statement at the following hierarchy levels:
• [edit policy-options]
• [edit logical-systems logical-system-name policy-options]
To include the AS path regular expression in a routing policy, include the as-path match
condition in the from statement:
as-path name regular-expression;
policy-statement policy-name {
term term-name {
from {
names;
}
}
}
Additionally, you can create a named AS path group made up of AS path regular
expressions and then include it in a routing policy with the as-path-group match condition.
To create a named AS path group, include the as-path-group statement:
as-path-group group-name {
name [ regular-expressions ];
}
You can include this statement at the following hierarchy levels:
• [edit policy-options]
• [edit logical-systems logical-system-name policy-options]
To include the AS path regular expressions within the AS path group in a routing policy,
include the as-path-group match condition in the from statement:
as-path-group group-name {
name [ regular-expressions ];
}
policy-statement policy-name {
term term-name {
96
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