Network Working Group                                       H. Berkowitz
Request for Comments: 1916                             PSC International
Category: Informational                                      P. Ferguson
                                                     cisco Systems, Inc.
                                                               W. Leland
                                                               P. Nesser
                                              Nesser & Nesser Consulting
                                                           February 1996

    Enterprise Renumbering: Experience and Information Solicitation

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.


   Because of the urgent need for, and substantial difficulty in,
   renumbering IP networks, the PIER working group is compiling a series
   of documents to assist sites in their renumbering efforts.  The
   intent of these documents is to provide both educational and
   practical information to the Internet community. To this end the
   working group is soliciting information from organizations that
   already have gone through, or are in the process of going through,
   renumbering efforts. Case studies, tools, and lists of applications
   that require special attention are sought.

Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.   Renumbering Experience . . . . . . . . . . . . . . . . . . . 4
   3.   Information on Tools . . . . . . . . . . . . . . . . . . . . 5
   4.   Application Information  . . . . . . . . . . . . . . . . . . 6
   5.   Security Considerations  . . . . . . . . . . . . . . . . . . 6
   6.   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 7
   A.   Formatting Rules (from RFC 1543) . . . . . . . . . . . . . . 8

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RFC 1916          Enterprise Renumbering Solicitation      February 1996

1. Introduction

   There are immediate and increasingly severe requirements to renumber
   both small and large-scale networks. The Procedures for
   Internet/Enterprise Renumbering (PIER) working group in the IETF
   urgently requests specific input for producing concrete guidance for
   the renumbering task as quickly as possible.  As part of collecting
   such information, the PIER working group therefore is soliciting
   input from people and organizations with experience in changing the
   IP addresses of enterprise networks or in making major changes in the
   subnetting of existing networks. We are especially interested in
   actual case studies -- that is, accounts describing what was actually
   done to renumber one or more networks.  Information is also solicited
   on specific tools used in the process, and on areas in which tools
   were needed but not available.  Because applications that use IP
   addresses directly in their configuration or security mechanisms pose
   specific difficulties and coordination issues for renumbering, a
   catalogue of such applications is being compiled.

   All interested parties are invited to submit material in any of these

   A) Accounts of the experience of renumbering networks:
   -- Retrospective reports on renumbering efforts.
   -- Journals or running accounts of a renumbering effort, written
      while the task is underway.

   B) Information on tools to help renumbering:
   -- Descriptions of tools used, whether commercial, freeware, or ad
      hoc (such as perl scripts).
   -- Descriptions of specific needs where a tool could clearly have
      helped, but none was found.

   C) Information on applications using embedded IP addresses:
   -- Software applications that use embedded IP addresses for security
      keys, authentication, or any other "inappropriate" purposes.
   -- Hardware devices whose IP addresses are hardcoded into the
      hardware design (and so may require extensive time lags to
   -- Both software and hardware whose vendors are no longer in business
      and that may require replacement or specialized solutions.

   The focus of this solicitation is on experience with renumbering that
   has been done or is now underway in IPv4 networks, and not on future
   changes to protocols or environments that may eventually be useful.
   We are especially concerned with the most common situation faced
   today: single-homed networks that are not transit providers. However,
   experience with renumbering more complex environments is also

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RFC 1916          Enterprise Renumbering Solicitation      February 1996


   The information provided will be used as an information base from
   which at least three documents will be composed: a document
   summarizing the processes to follow when renumbering, a document
   describing the available tools, and a document containing a list of
   known applications requiring special attention when renumbering. The
   information will also be available on the PIER home page, More specific reports on renumbering
   particular environments may also be produced in those cases where
   enough information is received from the community.

   Although our emphasis is on technical issues and responses, solidly
   based advice on smoothing the human problems is also appreciated.
   Political and cultural sensitivities, and handling them, are major
   issues in the real world.

   There is no requirement that a formal document be submitted, although
   with the permission of the submitter, selected accounts of experience
   in renumbering will be published by PIER as part of their planned
   series of case studies. If you wish to have your account released as
   a PIER case study, please follow the standard RFC format described in
   RFC 1543, "Instructions to RFC Authors". (For convenience, these
   formatting rules are given in Appendix A below.)

   The people and organization(s) involved and the network(s) renumbered
   need not be identified in any document made public by PIER: please
   explicitly indicate if a submission should have its anonymity

   The deadline for the submission of your information is May 15, 1996,
   though early submission is encouraged. Any information, however
   informally written, that can be submitted earlier, would be greatly
   appreciated and will help shape the further work of the PIER group.
   In particular, if you expect to submit a detailed write-up by May 15,
   1996, please let us know as soon as possible.

   Please send submissions, questions, or suggestions to the PIER
   discussion list,

   To subscribe to the PIER discussion list, please send your request to Further information on PIER is available on the
   PIER home page,

   Mail may also be sent directly to the editors, without its appearing
   on the PIER list, by sending to

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RFC 1916          Enterprise Renumbering Solicitation      February 1996

2.  Renumbering Experience

   An account of a renumbering effort should provide enough concrete
   information, based on actual experience, so that the reader can
   understand exactly what was done. Broadly speaking, we anticipate two
   styles of account:

   i) Retrospective reports

      Based on one or more renumbering efforts, recapitulate what was
      done and what was learned in the effort. Such a report should
      -- The environment being renumbered.
      -- The planning undertaken.
      -- What was done.
      -- What worked.
      -- What didn't (unanticipated issues, problems with planned

      In addition, the report would be even more useful if it also
      -- The reasons for taking the approach chosen.
      -- Any alternative approaches that were rejected, and why.
      -- What could have been done in advance to make the task easier.
      -- Lessons learned: how would you do it next time?

      It is hoped that individuals and organizations that have already
      been through a renumbering effort could quickly look back over
      their experiences, and capture their knowledge.

   ii) Running accounts

      Many people are in the midst of a renumbering effort, or are about
      to embark on one in the next few months. If, in the midst of that
      hectic task, one could write down a brief account or "diary" of
      what actually happens, as it happens, such a report is likely to
      capture the glitches and fixes of even the best-planned effort
      more accurately than any retrospective.

   Of course, these are only rough categories: any record of the
   experience of renumbering or of information gained by such experience
   can be a valuable contribution to PIER. When submitting accounts of
   renumbering efforts, please attempt to be as articulate and concise
   as possible.

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RFC 1916          Enterprise Renumbering Solicitation      February 1996

3.  Information on Tools

   Information on the tools that were used in renumbering is valuable,
   whether provided as a separate note or as part of an account of a
   renumbering effort. We welcome comments, however detailed or brief,
   on any tools that helped with renumbering, whether or not you intend
   to produce an account of the entire renumbering effort.

   Some areas in which tools may be used in renumbering include:
   -- Identifying what needs to be changed in your network, such as
      configuration files, hosts and servers with embedded or cached IP
      addresses, DNS, access control lists (ACLs), firewalls, routers,
      license servers, and other applications.
   -- Identifying external factors (such as remote servers, routers, and
      Internet registries) that need to be updated to accommodate your
      new numbers.
   -- Identifying dependencies between the different places where the
      numbers must be updated.
   -- Notifying external agents.
   -- Generating the new information (such as routing, configuration,
      and ACLs) required in order to carry out the updates.
   -- Coordinating updates.
   -- Making the updates.
   -- Verifying the updates.
   -- Trouble-shooting and debugging.
   -- Maintaining network functionality.
   -- Informing your users and other affected human beings (such as NOC
      staff) of the changes.

   The most useful tools are those that are, or can be, available to
   other renumbering efforts. For a given tool, it would be helpful to
   -- How to obtain it (if not a well-known tool).
   -- What you used it for.
   -- How you used it.
   -- What its strengths and limitations are for these specific uses.

   If a tool was created as part of the renumbering effort, a
   description of exactly what it does should be included. (For example,
   a script to check for IP addresses in configuration files on user
   machines should be described in terms of just what it did to obtain
   the list of machines, what files it looked for, and how it checked

   Although the primary goal of this solicitation is to learn what tools
   exist and are useful, we also value specific, experience-based
   descriptions of ways in which tools could have helped even though
   nothing was available during the renumbering to perform these

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RFC 1916          Enterprise Renumbering Solicitation      February 1996

   functions. Advisories on tools that appear to be useful but in
   practice created further problems may also be considered, as

4.  Application Information

   Information on applications that require special attention when
   renumbering are of particular interest, since specialized
   applications are among the most difficult aspects of renumbering.  It
   typically requires special intervention with the vendor to provide
   new security keys, new license addresses, new versions of
   applications, or perhaps even new hardware or proms to change the
   hardcoded IP addresses.

   A list of any such applications that required "extra" efforts during
   the renumbering process is valuable. Please include as much specific
   information as possible, including but not limited to: application
   name, version, platform, vendor, operating system, operating system
   version, the steps taken to overcome the problem, and lead times

   In particular, any applications that are no longer supported, or
   whose vendor has ceased to do business, are extremely important since
   these applications will likely be some of the more difficult issues a
   renumbering effort will encounter.  Any solutions to these types of
   problems, including replacement applications and proprietary
   solutions, are also sought.

5.  Security Considerations

   This RFC raises no security issues, although accounts of renumbering
   are encouraged to describe any security issues encountered, any tools
   that helped identify or resolve the issues, and the actions taken to
   address them. Submissions should give serious consideration to the
   content and context of issues regarding security.

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6.  Authors' Addresses

   Howard C. Berkowitz
   PSC International
   8260 Greensboro Drive, Suite 330
   McLean, VA 22102

   Phone: (703) 998-5819
   Fax: (703) 998-5058

   Paul Ferguson
   cisco Systems, Inc.
   1835 Alexander Bell Drive
   Suite 100
   Reston, VA 22091

   Phone: (703) 716-9538
   Fax: (703) 716-9538

   Will E. Leland
   Room 1A-228B
   445 South Street
   Morristown, NJ 07960-6438

   Phone: (201) 829-4376
   Fax: (201) 829-2504

   Philip J. Nesser II
   Nesser & Nesser Consulting
   16015 84th Ave. NE
   Bothell, WA 98011

   Phone: (206) 488-6268

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Appendix  A - Formatting Rules (from RFC 1543)

   Note: there are a set of NROFF formatting macros for the following
   format.  Please contact if you would like
   to get a copy.

3a.  ASCII Format Rules

   The character codes are ASCII.

   Each page must be limited to 58 lines followed by a form feed on a
   line by itself.

   Each line must be limited to 72 characters followed by carriage
   return and line feed.

   No overstriking (or underlining) is allowed.

   These "height" and "width" constraints include any headers, footers,
   page numbers, or left side indenting.

   Do not fill the text with extra spaces to provide a straight right

   Do not do hyphenation of words at the right margin.

   Do not use footnotes.  If such notes are necessary, put them at the
   end of a section, or at the end of the document.

   Use single spaced text within a paragraph, and one blank line between

   Note that the number of pages in a document and the page numbers on
   which various sections fall will likely change with reformatting.
   Thus cross references in the text by section number usually are
   easier to keep consistent than cross references by page number.

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