IP Addressing Fundamentals

Summary

Despite its beginning as an illegitimate child of an IETF ratified technology, “flexible subnetting” proved itself vastly superior to the original form of subnetting with fixed-length masks. In and of itself, VLSM (as it later became known) represented a tremendous advance in the sophistication of the IP address space. Yet it would have an even greater contribution in the future—a contribution that no one could have foreseen. You see, in the mid-1990s, the Internet was experiencing unprecedented, phenomenal growth. This growth rate sorely tested the scalability of the Internet's mechanisms, including its address space.

Sadly, the IP address space demonstrated that its original architecture was not up to the task. The IETF sprang into ...