Filtering routes and traffic packets

You can use the following components for route filtering when working with the BGP and OSPF protocols, and for filtering traffic packets when working with the PIM protocol:

• Access control lists (ACL) allow or deny the specified IPv4 prefixes.
• Prefix lists are an extended version of access control lists. Prefix lists additionally allow or deny subnet mask ranges. You can use prefix lists in route maps.
• Route maps are an extended version of prefix lists. Route maps additionally modify attribute values.

You can create rules in access control lists, prefix lists, and route maps. Each rule is numbered. The rule with the lowest sequence number is the first to be applied to an IPv4 prefix. If none of the rules can be applied, the IPv4 prefix is denied.