I'm currently trying to understand the concept of dCEF and how it works. I have a pretty straightforward question. I would like to know if when using dCEF the FIB is distributed equally among all Layer 3 forwarding engines so that each of them has the same FIB or the FIB is spread amongst all of them as each of them contains just a part of the whole FIB. I hope someone can give me an explantion about it since it's a bit unclear in the Cisco Press book I am currently reading. Thank you
I think glen is right.. When dCEF is enabled, line cards maintain identical copies of the FIB and adjacency tables. The line cards can perform the express forwarding by themselves, relieving the main processor - Route Processor (RP) - of involvement in the switching operation.
dCef is distributed Cisco Express forwarding.dCEF is used in high-end switches and Cisco routers. On 6500/7600 for dCEF to work you need the DFC's (distributed feature card) which is actually a PFC which used on Supervisor engine. This DFC is a Layer2/3 packet rewrite engine and downloads the CEF FIB and Adjacenecy tables on itself. Once the line-card has CEF FIB and adjacency table downloaded from the RP it locally writes the packet and hence doesn local switching.
With dCEF enable cards even the first packet doesnot go to the CPU for processing unless the traditional MLS where the first packet goes to the CPU and then the subsequent packets are written locally.There are certain conditions if they donot meet then the packet goes to the CPU for processing like TTL expire,MTU exceded etc...
With DFC enabled on the 6500/7600 switches, the performance of the switch increases to 400+ MPPS.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.