CCNP Routing and Switching ROUTE 300-101 Official Cert Guide

Filtering by Referencing IP Prefix Lists

The Cisco IOS IP prefix-list feature gives the network engineer another tool for matching routes when performing route filtering. IP prefix lists can examine both the prefix and the prefix length, and a range of prefixes or a range of prefix lengths. The command then sets either a deny or permit action for each matched prefix/length. To use the prefix list, the configuration simply refers to the prefix-list with the same distribute-list command seen earlier.

Using IP prefix lists for route filtering has several advantages. First, IP prefix lists allow matching of the prefix length, whereas the ACLs used by the EIGRP distribute-list command cannot. (Some other route filtering configurations can match both ...