System Administration Guide: IP Services

IPv4 Autonomous System Topology

Sites with multiple routers and networks typically administer their network topology as a single routing domain, or autonomous system (AS) . The following figure shows a typical network topology that would be considered a small AS. This topology is referenced in the examples throughout this section.

Figure 5–3 Autonomous System With Multiple IPv4 Routers

This topology diagram of an autonomous system is explained
in the following context.

The figure shows an AS that is divided into three local networks,,, and 192.168.5. Four routers share packet-forwarding and routing responsibilities. The AS includes the following types of systems: