Deciding Where to Go Next

Deciding Where to Go Next

Routers perform routing by looking at the destination IP address of the IP packet. The term routing refers to the process by which a router examines a recently received packet, looks at the destination IP address, and makes a decision about where to forward the packet next.

The key to understanding the process of routing revolves around the IP routing table. The IP routing table includes a list of IP network or subnet numbers, along with instructions on how this router should forward packets in order to deliver the packets to that network or subnet. Whew, that's a long definition, but the concept is simple, particularly with an example. Figure 11-10 shows R1's routing table.