Understanding the network.pdf - Back to Home

classful-based address space model. Although classful routing would continue to be
used at the local network end, the Internet backbones would use CIDR. Instead of
building large tables of classful routes, CIDR builds single routes based on
summaries of contiguous addresses.
Figure 2.6 shows an example where, under classful addressing, each of these Class
C addresses would require a route for each address space.
Figure 2.6. A comparison of classful and classless
network address expressions.
In classless mode, the address group is expressed as a single network. The network
loopback address is 192.160.0.0, and the network broadcast address is
192.160.7.255. The goal with CIDR is to provide a single route to the gateway that
leads to the network(s), as shown in Figure 2.7. How the actual address space is
subnetted is of no concern to CIDR, which only provides the summarized route.