Perfect numbers like perfect men are very rare.
This chapter focuses on common tasks everyone will have to perform while preparing for their IPv6 transitions, no matter the nature of their enterprise or the market segment it occupies. If not performed during the preparation phase, these tasks must be performed very early in the execution phase. If you're to have a successful transition, you'll need to acquire IPv6 addresses and external connectivity, and you'll need to document properly what you get and how you use it. The preceding sentence summarizes what 80 percent of the chapter covers and, in doing so, trivializes it to the point where many organizations don't put enough forethought into the work involved and wind up numbering themselves into a corner. With such organizations, the moment they open a new facility or launch a new program or product line, they find their numbering "plan" coming up short and have to renumber a whole site or more. Your aim (as well as that of any other MIS/IT professional) is to do the legwork up front so you won't have to renumber for the next five years after your upgrade is done.
No matter which IPv6 transition project you're currently undertaking, be this the first one that establishes an IPv6 backbone and perhaps a few outposts in the network's outer rim, or a subsequent one that adds new capabilities or brings new facilities or subnets into the IPv6 ...