How can router decide so fast?
January 16, 2015
Routing
Cisco created all sorts of different magic inside their boxes that optimize forwarding processing of packets.
Main router function is fairly self-explanatory. Router performs IP forwarding more often called IP routing. IP routing is process of deciding where to send the packet after it was received.
IP Routing explained in detail
Logic behind IP forwarding is listed in steps here with the assumption it will be an IPv4 packet that was received. This is process switching explained in 11 steps: