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

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