Cisco Express Forwarding (CEF)

A Cisco proprietary switching mechanism, Cisco Express Forwarding has been the default switching mechanism on most Cisco platforms that do all their packet switching and forwarding using the general purpose CPU since the 1990s, and is the default switching mechanism used by all Cisco platforms that use specialised ASICs and Network Processing Units (NPUs) for high packet throughput.

The general purpose CPU on both software and hardware based platforms are similar and perform all the same functions. There is a difference on software based platforms that the general purpose CPU is in charge of all operations including CEF (based in software) and hardware based platforms do CEF switching in specialised ASICs, tenary content addressable memory (TCAM) and NPUs (Hardware CEF).




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