With Fast Switching, the forward information database (fib) is built gradually on an as needed basis. It starts empty and is built as users need to find destinations.
With the first packet a user sends to destination $x, the ip routing table (rib) is consulted to find the outbound interface toward the ip address of the destination, the arp table is consulted to find the mac addy of the next hop. Being that looking up the destination via the ip routing table/rib is done in software (process switched), it takes more resources to perform this action.
After the lookup, the destination ip and outbound interface is sent to the fib so all subsequent packets to this destination do not have to be looked up (per ip routing table/rib).
With CEF, the full RIB is pushed/mirrored to the CEF FIB after boot so the router/switch does not have to gradually build the CEF FIB. Also MAC addresses for the next hop are contained in the Adjacency table. There is a hash table with pointers from the FIB to the Adjacency Table. This makes it easier for this entire process of packet switching to be programmed into hardware. Subsequently, the first packet sent to a destination does not have to be sent to software unless particular security related features are enabled. In the case of 6500 switches with linecards containing DFC/Distributed Forwarding Cards, each linecard will have a copy of the CEF FIB and Adjacency Table so the packet switching can be done on the linecard.
I've readed ur last post, I would like to know one thing, As far as I know that MPLS is usinf (Fast Switching) Technology, and since the process of it's lookup is so different from CEF, Then Does CEF is better performance wise than using MPLS technology?
Thank you for the explanation between Fast Switching and CEF. I have only one question related to CEF. You mention "paticular security related features" in the case of bumping packets to software. Would having in inbound ACL together with CBAC qualify as situation where packets are process switched?
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.