The topology displayed in Figure 1 is used as the reference topology for this section. Notice that in the topology:
- R1 is the edge router that connects to the Internet. Therefore, it is propagating a default static route to R2 and R3.
- R1, R2, and R3 contain discontiguous networks separated by another classful network.
- R3 is also introducing a 192.168.0.0/16 supernet route.
Figure 2 displays the IPv4 routing table of R1 with directly connected, static, and dynamic routes.
Note: The routing table hierarchy in Cisco IOS was originally implemented with the classful routing scheme. Although the routing table incorporates both classful and classless addressing, the overall structure is still built around this classful scheme.