1. Introduction

   Organizations can decide to renumber part or all of their IP address
   space for a variety of reasons.  Overall motivations for renumbering
   are discussed in [RFC2071].  This document deals with the router-
   related aspects of a renumbering effort, once the decision to
   renumber has been made.

   A renumbering effort must be well-planned if it is to be successful.
   This document deals with planning and implementation guidelines for
   the interconnection devices of an enterprise. Of these devices,
   routers have the clearest association with the IP numbering plan.

   Planning begins with understanding the problem to be solved.  Such
   understanding includes both the motivation for renumbering and the
   technical issues involved in renumbering.

      1.  Begin with a short and clear statement of the reason to
          renumber.  Section 3  of this document discusses common
          reasons.

      2.  Understand the principles of numbering in the present and
          planned environments.  Section 4 reviews numbering and
          suggests a method for describing the scope of renumbering.

      3.  Before the actual renumbering, it can be useful to evolve
          the current environment and current numbering to a more
          "renumbering-friendly" system.  Section 5 discusses ways to
          introduce renumbering friendliness into current systems.

      4.  Be aware of potential pitfalls.  These are discussed in
          Section 6.

      5.  Identify potential requirements for tools, discussed in
          Section 7.

      6.  Evaluate the specific router mechanisms that will be affected
          by renumbering.  See Sections 8 through 13.

      7.  Set up a specific transition plan framework.  Guidelines
          for such planning are in Section 15.

   When trying to understand the interactions of renumbering on routers,
   remember there different aspects to the problem, depending on the
   scope of the renumbering involved.  Remember that even an
   enterprise-wide renumbering probably will not affect all IP addresses
   visible within the enterprise, since some addresses (e.g., Internet
   service providers, external business partners) are outside the
   address space under the control of the enterprise.