What Is Cisco IOS Switching?
Cisco IOS switching defines the packet flow through the router. More specifically, it determines how quickly the packet can be forwarded through the router, and also in which physical buffers the packets are stored. During the history of Cisco IOS, multiple switching methods have been developed. Some methods are supported only on particular platforms. CEF is the latest switching method. When CEF is enabled globally (default behavior), the ip route-cache cef interface specific command is also enabled. This command ensures CEF switching is done for packets that enter this interface. Occasionally, if needed to disable CEF on one interface alone, the no ip route-cache cef command is added. This disables CEF switching for that interface alone. Cisco IOS does not add the no ip route-cache command to the running-config on its own when it is forced to disable CEF. It was introduced on many platforms in Cisco IOS 12.0 mainline, particularly low- and mid-range platforms such as the Cisco 1600, 2
