Routing Policy Application to Routing Protocols

You can apply the following routing policy elements to a routing protocol:

Routing policy—You can apply a single routing policy to a routing protocol.
Chain of routing policies—You can apply multiple routing policies (chains) to a routing protocol.
Policy expression—You can apply a policy expression to a routing protocol. A policy expression uses Boolean logical operators with a routing policy and routing policy chains. The logical operators establish rules by which the policy or chains are evaluated.