Fifteen years ago or more I was listening to a presentation by Vint Cerf where he was advocating for the adoption of CIDR as a solution to many of the routing issues the core Internet providers were facing at the time. In responding to his critics, he made an off-handed comment to the effect that, “People say to me, ‘Vint, you can have my IP prefix when you pry it out of my cold, dead fingers.’ To which I respond, ‘Remember you said dead.'”
Needless to say, this got a huge laugh out of the audience. But the kernel of this little comment is a nugget of IT wisdom that applies in so many different situations. To state it more plainly, there are times of compelling change when the most sensible course is to simply ignore the current installed base issues and just move forward. By the time you’ve finished your new roll-out, today’s installed base will be completely subsumed into the new technology.
In Vint’s case, his position was spectacularly vindicated of course, because the number of Internet-connected hosts grew by an order of magnitude during the period when CIDR was being rolled-out. But this kind of thinking also applies equally well on a smaller scale to operational issues faced by many IT operations. Have new baseline images you want to roll out to your organization but are meeting resistance from your user community? Roll the images out on newly deployed systems only and wait for attrition to take care of the existing installed base. Given the cycle rate of technology in most organizations, that gives you a half-life of change in about 18 months.