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Cisco CEF

Hi This a general query I want to know about CEF. As I understood CEF is kind of switching technology used in router for faster processing as it is ASIC hardware ... it's works on wire speed. have two tables..... FIBand adjancency table which farwards packet. Now my query is is it always a hardware dependent feature. If I have a router of old version is CEF is possible to enable. I also heard that there are two types of CEF... centrallized and distributed. .... so CCEF----- is IOS dependent and DCEF is hardware dependent. I right ????? Ragards Gan

Everyone's tags (1)

Hi i am just reposting my

Hi i am just reposting my query as i didn't got any response.


i want to understand the difference between CCEF and DCEF... is CCEF can be any enabled in any device if the IOS is supported?

Also DCEF ... will be a part of Line card where you need the special hardware to support and not all liine card have this capability. So i am assuming that it is hardware dependent?


So CCEF --- it's like IOS related feature whereas DCEF is hardware related one.




Cisco Employee

Hi Gan,There is nothing is

Hi Gan,

There is nothing is CCEF which I am aware of.


CEF :- When Cisco Express Forwarding is enabled on a router, the Route Processor (RP) performs the express forwarding.(


isco Express Forwarding (CEF) is advanced, Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

CEF was introduced on many platforms in Cisco IOS 12.0 mainline, particularly low- and mid-range platforms such as the Cisco 1600, 2500, and 3600 Series

(You can also check by using the command : show ip cef-- this would give you the info).

Dcef:-DCEF is distributed Cisco Express Forwarding. Normal CEF is where the supervisor engine holds the forwarding table and the adjacency/neighbour table and makes forwarding decisions for every line card. The main difference with dCEF is that each line card holds a copy of the neighbour table and forwarding table and can make forwarding decisions for itself. This takes burden of the Supervisor engine and speeds up packet forwarding





*Plz rate if this info is usefull/helpfull.


Cisco Employee

Hi,Very true cef is a


Very true cef is a advancement of fast switching and is platform/hardware dependent. Below are few links to understand CEF in details:

Thanks & Regards


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