The following figure shows the three distinct filter stages that are applied to IP traffic.
These stages are:
Filter stage 1 is the accept policy or in filter that applies to incoming traffic to detect changes in the dynamic (protocol-learned) routing information, which are then submitted to the routing table.
Filter stage 2 is the redistribution filter that applies to the entries in the routing table to the protocol during the leaking process.
Filter stage 3 is the announce policy or out filter that applies to outgoing traffic within a protocol domain.
The following figure shows the logical process for route filtering on the switch.
