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Step 1, on the left of Figure 1-10, begins with Larry being ready to send an IP packet. Larry’s IP process chooses to send the packet to some router—a nearby router on the same LAN—with the expectation that the router will know how to forward the packet. (This logic is much like you or me sending all our letters by putting them in a nearby mailbox.) Larry doesn’t need to know anything more about the topology or the other routers.

At Step 2, Router R1 receives the IP packet, and R1’s IP process makes a decision. R1 looks at the destination address (2.2.2.2), compares that address to its known IP routes, and chooses to forward the packet to Router R2. This process of forwarding the IP packet is called IP routing (or simply routing).

At Step 3, Router R2 repeats the same kind of logic used by Router R1. R2’s IP process will compare the packet’s destination IP address (2.2.2.2) to R2’s known IP routes and make a choice to forward the packet to the right, on to Bob.

You will learn IP to more depth than any other protocol while preparing for CCNA. More than half the chapters in this book discuss some feature that relates to addressing, IP routing, and how routers perform routing.