IP Addressing Fundamentals

Implementation Topologies

Although NAT was originally conceived for a single purpose (staving off address-space depletion), it has proven itself remarkably versatile. Today, NAT can be used to support numerous, vastly different network topologies. In addition to the simple stub network connected to the Internet (as you saw in Figure 7-1), some of the more common implementation varieties include the following:

• Private network with multiple egress points

• Partitioned-backbone stub network

• Using NAT for a subset of IP addresses in a network

We'll look at each in a bit more detail throughout this section.

NOTE

Since its inception, NAT has become almost synonymous with the nonunique private IP addresses reserved in RFCs 1597 and 1918. However, nothing ...