Rpl Variables; Routing Policy Configuration Basics; Policy Definitions - Cisco ASR 9000 Series Configuration Manual

Implementing Routing Policy
set community (no-export) additive
endif
end-policy

RPL Variables

RPL Variables helps user to mark policy execution flow by setting value to the variables and the value stored
in the variables can be used in conditional statements to perform actions based on the execution flow. The
values are set using the var globarVarN command in route-policy configuration mode.

Routing Policy Configuration Basics

Route policies comprise series of statements and expressions that are bracketed with the route-policy and
end-policy keywords. Rather than a collection of individual commands (one for each line), the statements
within a route policy have context relative to each other. Thus, instead of each line being an individual
command, each policy or set is an independent configuration object that can be used, entered, and manipulated
as a unit.
Each line of a policy configuration is a logical subunit. At least one new line must follow the then , else ,
and end-policy keywords. A new line must also follow the closing parenthesis of a parameter list and the
name string in a reference to an AS path set, community set, extended community set, or prefix set. At least
one new line must precede the definition of a route policy, AS path set, community set, extended community
set, or prefix set. One or more new lines can follow an action statement. One or more new lines can follow a
comma separator in a named AS path set, community set, extended community set, or prefix set. A new line
must appear at the end of a logical unit of policy expression and may not appear anywhere else.

Policy Definitions

Policy definitions create named sequences of policy statements. A policy definition consists of the CLI
route-policy keyword followed by a name, a sequence of policy statements, and the end-policy keyword.
For example, the following policy drops any route it encounters:
route-policy drop-everything
drop
end-policy
The name serves as a handle for binding the policy to protocols. To remove a policy definition, issue the no
route-policy name command.
Policies may also refer to other policies such that common blocks of policy can be reused. This reference to
other policies is accomplished by using the apply statement, as shown in the following example:
route-policy check-as-1234
if as-path passes-through '1234.5' then
apply drop-everything
else
pass
endif
end-policy
OL-30423-03
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
Routing Policy Configuration Basics
479