CCIE Practical Studies: Security (CCIE Self-Study)

Overview of Access Control Lists

ACLs are used to filter network traffic, often referred to as packet filtering, by deciding whether routed packets are forwarded or blocked at your router's interfaces. An ACL contains an ordered list of access control entries (ACEs). Each ACE specifies whether to permit or deny a packet based on a set of conditions that the packet must satisfy to match the ACE. The meaning of permit or deny depends on the context in which the ACL is used. The router examines each packet as it enters or before it exits an interface to determine whether to forward or drop the packet.

Use crypto access lists to define which IP traffic you want to be protected by crypto and which traffic you do not want to be protected by crypto. ...