Discussion of Conceptual Difference Between Cisco IOS Classic and Zone-Based Firewalls

Cisco IOS has supported stateful inspection firewall capability since before Cisco IOS Software Version 12.0. Stateful Inspection Firewall features are supported through the Classic Firewall (formerly known as Context-Based Access Control, or CBAC). Cisco IOS Software introduced an additional configuration model for stateful inspection with the Zone-Based Policy Firewall (ZFW) in Cisco IOS Software version 12.4(6)T. Cisco IOS Software Classic Firewall will continue to be maintained for the foreseeable future, but will not be significantly enhanced with new features. Instead, the strategic development direction for Cisco IOS Software's stateful inspection firewall is carried by Zone-Based Policy firewall.