CCENT Cisco Certified Entry Networking Technician Study Guide: (ICND1 Exam 640-822), 2nd Edition

The IP Routing Process

The IP routing process is fairly simple and doesn't change, regardless of the size of your network. For an example, I'll use Figure 6.2 to describe step-by-step what happens when Host_A wants to communicate with Host_B on a different network.

FIGURE 6.2 IP routing example using two hosts and one router

In this example, a user on Host_A pings Host_B's IP address. Routing doesn't get simpler than this, but it still involves a lot of steps. Let's work through them.

1. Internet Control Message Protocol (ICMP) creates an echo request payload (which is just the alphabet in the data field).
2. ICMP hands that payload to Internet Protocol ...