IP Addressing Fundamentals

Predefining with Symmetrical Gaps

The next logical step is to take an address space, presubnet it, and add symmetrical gaps between the preassigned blocks. This is one of the more elegant and sophisticated approaches to managing an address space, but it is difficult to describe. The goal of such an approach is to maintain some semblance of symmetry and order. Scanning back through the tables presented in previous sections, you can see that there's a bit of a “rat's nest” look to the address assignments. In other words, blocks were created as they were needed, and there is no rhyme or reason to the juxtaposition of different block sizes.

One tactic you can use to maintain a more orderly appearance is to preallocate blocks based on prefix size. ...