1. INTRODUCTION

   Growth in use of Internet technology and in attachments to the
   Internet have taken us to the point that we now are in danger of
   running out of unassigned IP network numbers.  Initially, numbers
   were formally assigned only when a network was about to be attached
   to the Internet.  This caused difficulties when initial use of IP
   substantially preceded the decision and permission to attach to the
   Internet.  In particular, re-numbering was painful.  The lesson that
   we learned was that every IP address ought to be globally unique,
   independent of its attachment to the Internet.  This makes it
   possible for any two network entities to communicate, no matter where
   either might be located.  This model is the result of a decades-long
   evolution, through which the community realized how painful it can be
   to convert a network of computers to use an assigned number after
   using random or default addresses found on computers just out of the
   box.  RFC 1597(-> 1918) abrogates this model without benefit of general IETF
   community discussion and consensus, leaving policy and operational
   questions unasked and unanswered.