Section 8.2: CEF Operation Modes
CEF can be enabled in one of two modes: Central CEF Mode; and Distributed CEF Mode (dCEF)
• When in Central CEF Mode is enabled, the CEF FIB and adjacency tables reside on the route processor, and the route processor performs the express forwarding. This mode can be used when line cards, such as VIP line cards or GSR line cards, are not available for CEF switching or when you need to use features not compatible with distributed CEF switching.
• When Distributed CEF Mode (dCEF) is enabled, line cards maintain an identical copy of the FIB and adjacency tables. The line cards perform the express forwarding between port adapters, relieving the RSP of involvement in the switching operation. dCEF uses an Inter Process Communication (IPC) mechanism to ensure synchronization of FIBs and adjacency tables on the route processor and line cards.
Note: The Cisco 12000 series Routers operate only in dCEF mode; dCEF switching cannot be configured on the same VIP card as distributed fast switching, and dCEF is not supported on Cisco 7200 series routers.