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There are three major switching mode in Cisco devices. Here is the three switching methods with commands to enable it.

1. Process Switching

– Everytime when router pass packets, check routing table before forward packets
– Load-balanced by packet
– CPU intensive
– Slow siwtching speed
– If more than one paths are avaiable, packets will be distributed into availabe paths by packet

Router(config-if)# no ip route-cache

 

2. Fast Switching

– It is a default switching method on cisco products
– When router pass packets, check routing table for very first packet. And router will check caching table from the second packets and later
– It caches destination addresses and paths for the destiantions
– Load-balanced by destination

Router(config-if)# ip route-cache

 

3. CEF(Cisco Express Forwarding) Switching

– Improved from Fast Switching
– Fast Switching need to process Process Switching to get update caching table. However, CEF switching copys entire routing table into cashing table.
– CEF provide fast caching machnisim
– It caches destination addresses, source addresses and paths for the destiantions
– Load-balanced by source, destination and packet

ip load-sharing per-packet
Router(config)# ip cef