Nonattached Policy Modification - Cisco NCS 6000 Series Configuration Manual

Implementing Routing Policy
Note A route policy or set that is in use at an attach point cannot be removed because this removal would result in
an undefined reference. An attempt to remove a route policy or set that is in use at an attach point results in
an error message to the user.

Nonattached Policy Modification

As long as a given policy is not attached at an attach point, the policy is allowed to refer to nonexistent sets
and policies. Configurations can be built that reference sets or policy blocks that are not yet defined, and then
later those undefined policies and sets can be filled in. This method of building configurations gives much
greater flexibility in policy definition. Every piece of policy you want to reference while defining a policy
need not exist in the configuration. Thus, you can define a policy sample1 that references a policy sample2
using an apply statement even if the policy sample2 does not exist. Similarly, you can enter a policy statement
that refers to a nonexistent set.
However, the existence of all referenced policies and sets is enforced when a policy is attached. Thus, if a
user attempts to attach the policy sample1 with the reference to an undefined policy sample2 at an inbound
BGP policy using the statement neighbor 1.2.3.4 address-family ipv4 unicast policy sample1 in, the
configuration attempt is rejected because the policy sample2 does not exist.
Editing Routing Policy Configuration Elements
RPL is based on statements rather than on lines. That is, within the begin-end pair that brackets policy statements
from the CLI, a new line is merely a separator, the same as a space character.
The CLI provides the means to enter and delete route policy statements. RPL provides a means to edit the
contents of the policy between the begin-end brackets, using a text editor. The following text editors are
available on Cisco IOS XR software for editing RPL policies:
• Nano (default)
• Emacs
• Vim
Editing Routing Policy Configuration Elements Using the Nano Editor
To edit the contents of a routing policy using the Nano editor, use the following CLI command in XR EXEC
mode:
edit route-policy
name
nano
Routing Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
Nonattached Policy Modification
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