The following are examples of circumstances of when to configure and apply unique route policies.
When you want to control the protocol to allow all routes to be imported into the routing table. This enables the routing table to learn about particular routes to enable packet forwarding and redistributing packets into other routing protocols.
When you want to control the exporting of a protocol’s learned active routes.
When you want a routing protocol to announce active routes learned from another routing protocol, which is sometimes called route redistribution.
When you want unique behaviors to control route characteristics. For example, change the route preference.
When you want unique behaviors to control route characteristics. For example, change the route preference, AS path, or community values to manipulate the control the route selection.
When you want to control BGP route flapping (damping).