Taking Action When a Match Occurs
When using IP ACLs to filter packets, only one of two actions can be chosen. The configuration commands use keywords deny and permit, and they mean (respectively) to discard the packet or to allow it to keep going as if the ACL did not exist.
This book focuses on using ACLs to filter packets, but IOS uses ACLs for many more features. Those features typically use the same matching logic. However, in other cases, the deny or permit keywords imply some other action. For example, Chapter 24, “Network Address Translation,” uses ACLs to match packets, but matching with a permit keyword tells the router to apply NAT functions that translate the IP addresses.
Get CCENT/CCNA ICND1 100-101 Official Cert Guide now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
