130 likes | 552 Views
process switching fast switching cef. Amy Ramirez Na Li Steffi Zinto. Process Switching. An operation that provides full route evaluation and per-packet load balancing across parallel WAN links
E N D
process switchingfast switching cef Amy Ramirez Na Li Steffi Zinto
Process Switching • An operation that provides full route evaluation and per-packet load balancing across parallel WAN links • Involves the transmission of entire frames to the router CPU, where they are repackaged for delivery to or from a WAN interface • The most resource –intensive switching operation that the CPU can perform
Differences • Process switching • Requires the CPU to be personally involved with every forwarding decision.
Fast switching • Still uses the CPU, after a packet has been forwarded-- information stored in a fast-switching cache. • If the information is not cached--the CPU will have a similar workload, for that packet • Drawbacks: • --1st packet • --timed out quickly
Cisco Express Forwarding (CEF) • Building a Forwarding Information Base (FIB), and an adjacency table. • Contains pre-computed reverse lookups, next hop information (All the stuff a router would have to consider when forwarding a packet).
How a Cisco router can be configured to implement • Process Switching • --By Default