hi every body!
do all the switches\routers which provide hard-based cef, use switch engine not the main processor for layer3 switching?
Which are the switches and routers which provide software -based cef? is main processor used for software-based cef?
thanks a lot and have a nice day!
yes it is the main cpu that builds FIB and adjacency tables and this actually happens on all platforms because all messages like CDP, ARP, routing protocol messages are sent to the main CPU for process switching.
Hardware based CEF platforms can have additional resources like DFC in C6500 linecards that can store a complete copy of the CEF tables and are used by ASIC chips for forwarding. The same happens in the GSR linecards and on CRS.
In these distributed platforms the main cpu has the duty to build the CEF tables, to update them and to send a copy to all linecards or modules that use them.
In a ISR or other routers like c2600 the CEF tables are built by the main cpu and used by other sw processes running over it like IP input and so on.
Hope to help