Basic guidelines

IPv6 addressing plans are very different from IPv4 addressing plans, and this is a good thing. IPv4 plans are constrained by the limited available address space, making it necessary to make some suboptimal choices. IPv6 provides such an immense address space that the addressing plan can be structured in a much more convenient and optimal way.

While this sounds simple, this enhanced freedom requires a different way of looking at addresses. This mental shift is often the hard to make, especially for those that have been operating IPv4 networks for a long time.

Further reading