RFC 3789 INFORMATIONAL IPV6 · TRANSITION · SURVEY

Introduction to the Survey of IPv4 Addresses in Currently Deployed IETF Standards Track and Experimental Documents

Cataloging IPv4 dependencies in IETF standards to guide the transition to IPv6.

On rfc-editor.org ↗
PUBLISHED
June 2004
AUTHORS
P. Nesser, II, A. Bergstrom
STREAM
IETF
TOTAL RFCS SURVEYED
877
RFCS WITH IPV4 DEPENDENCIES
173 (19.7%)
PAGES EXAMINED
Approximately 25,000
FULL STANDARDS WITH IPV4 DEPENDENCIES
30 out of 68 (44%)
ROUTING AREA RFCS WITH DEPENDENCIES
23 out of 46 (50%)
DOI
10.17487/RFC3789

RFC text

Contents
Original text · RFC Editor View on rfc-editor.org ↗
Network Working Group                                      P. Nesser, II
Request for Comments: 3789                    Nesser & Nesser Consulting
Category: Informational                                A. Bergstrom, Ed.
                                              Ostfold University College
                                                               June 2004


            Introduction to the Survey of IPv4 Addresses in
   Currently Deployed IETF Standards Track and Experimental Documents

Status of this Memo

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

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document is a general overview and introduction to the v6ops
   IETF workgroup project of documenting all usage of IPv4 addresses in
   IETF standards track and experimental RFCs.  It is broken into seven
   documents conforming to the current IETF areas.  It also describes
   the methodology used during documentation, which types of RFCs have
   been documented, and provides a concatenated summary of results.

Table of Contents

   1.0.  Introduction . . . . . . . . . . . . . . . . . . . . . . . .  2
         1.1.  Short Historical Perspective . . . . . . . . . . . . .  2
         1.2.  An Observation on the Classification of Standards. . .  3
   2.0.  Methodology. . . . . . . . . . . . . . . . . . . . . . . . .  4
         2.1.  Scope. . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.0.  Summary of Results . . . . . . . . . . . . . . . . . . . . .  5
         3.1.  Application Area Specifications. . . . . . . . . . . .  5
         3.2.  Internet Area Specifications . . . . . . . . . . . . .  5
         3.3.  Operations and Management Area Specifications. . . . .  6
         3.4.  Routing Area Specifications. . . . . . . . . . . . . .  6
         3.5.  Security Area Specifications . . . . . . . . . . . . .  6
         3.6.  Sub-IP Area Specifications . . . . . . . . . . . . . .  6
         3.7.  Transport Area Specifications. . . . . . . . . . . . .  7
   4.0.  Discussion of "Long Term" Stability of Addresses on
         Protocols. . . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.0.  Security Considerations. . . . . . . . . . . . . . . . . . .  8
   6.0.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  8
   7.0.  References . . . . . . . . . . . . . . . . . . . . . . . . .  8
         7.1.  Normative References . . . . . . . . . . . . . . . . .  8
   8.0.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . .  9
   9.0.  Full Copyright Statement . . . . . . . . . . . . . . . . . . 10

1.0.  Introduction

   This document is the introduction to a document set aiming to
   document all usage of IPv4 addresses in IETF standards.  In an effort
   to have the information in a manageable form, it has been broken into
   7 documents, conforming to the current IETF areas (Application [1],
   Internet [2], Operations and Management [3], Routing [4], Security
   [5], Sub-IP [6], and Transport [7]).  It also describes the
   methodology used during documentation, which types of RFCs that have
   been documented, and provides a concatenated summary of results.

1.1.  Short Historical Perspective

   There are many challenges that face the Internet Engineering
   community.  The foremost of these challenges has been the scaling
   issue: how to grow a network that was envisioned to handle thousands
   of hosts to one that will handle tens of millions of networks with
   billions of hosts.  Over the years, this scaling problem has been
   managed, with varying degrees of success, by changes to the network
   layer and to routing protocols.  (Although largely ignored in the
   changes to network layer and routing protocols, the tremendous
   advances in computational hardware during the past two decades have
   been of significant benefit in management of scaling problems
   encountered thus far.)

   The first "modern" transition to the network layer occurred during
   the early 1980's, moving from the Network Control Protocol (NCP) to
   IPv4.  This culminated in the famous "flag day" of January 1, 1983.
   IP Version 4 originally specified an 8 bit network and 24 bit host
   addresses, as documented in RFC 760.  A year later, IPv4 was updated
   in RFC 791 to include the famous A, B, C, D, and E class system.

   Networks were growing in such a way that it was clear that a
   convention for breaking networks into smaller pieces was needed.  In
   October of 1984 RFC 917 was published formalizing the practice of
   subnetting.

   By the late 1980's, it was clear that the current exterior routing
   protocol used by the Internet (EGP) was insufficiently robust to
   scale with the growth of the Internet.  The first version of BGP was
   documented in 1989 in RFC 1105.

   Yet another scaling issue, exhaustion of the class B address space
   became apparent in the early 1990s.  The growth and commercialization
   of the Internet stimulated organisations requesting IP addresses in
   alarming numbers.  By May of 1992, over 45% of the Class B space had
   been allocated.  In early 1993 RFC 1466 was published, directing
   assignment of blocks of Class C's be given out instead of Class B's.
   This temporarily circumvented the problem of address space
   exhaustion, but had a significant impact of the routing
   infrastructure.

   The number of entries in the "core" routing tables began to grow
   exponentially as a result of RFC 1466.  This led to the
   implementation of BGP4 and CIDR prefix addressing.  This may have
   circumvented the problem for the present, but they continue to pose
   potential scaling issues.

   Growth in the population of Internet hosts since the mid-1980s would
   have long overwhelmed the IPv4 address space if industry had not
   supplied a circumvention in the form of Network Address Translators
   (NATs).  To do this, the Internet has watered down the underlying
   "End-to-End" principle.

   In the early 1990's, the IETF was aware of these potential problems
   and began a long design process to create a successor to IPv4 that
   would address these issues.  The outcome of that process was IPv6.

   The purpose of this document is not to discuss the merits or problems
   of IPv6.  That debate is still ongoing and will eventually be decided
   on how well the IETF defines transition mechanisms and how industry
   accepts the solution.  The question is not "should," but "when."

1.2.  An Observation on the Classification of Standards

   It has become clear during the course of this investigation that
   there has been little management of the status of standards over the
   years.  Some attempt has been made by the introduction of the
   classification of standards into Full, Draft, Proposed, Experimental,
   and Historic.  However, there has not been a concerted effort to
   actively manage the classification for older standards.  Standards
   are only classified as Historic when either a newer version of the
   protocol is deployed and it is randomly noticed that an RFC describes
   a long dead protocol, or a serious flaw is discovered in a protocol.
   Another issue is the status of Proposed Standards.  Since this is the
   entry level position for protocols entering the standards process,
   many old protocols or non-implemented protocols linger in this status
   indefinitely.  This problem also exists for Experimental RFCs.
   Similarly, the problem exists for the Best Current Practices (BCP)
   and For You Information (FYI) series of documents.

   To exemplify this point, there are 61 Full Standards, only 4 of which
   have been reclassified to Historic.  There are 65 Draft Standards,
   611 Proposed Standards, and 150 Experimental RFCs, of which only 66
   have been reclassified as Historic.  That is a rate of less than 8%.
   It should be obvious that in the more that 30 years of protocol
   development and documentation, there should be at least as many (if
   not a majority of) protocols that have been retired compared to the
   ones that are currently active.

   Please note that there is occasionally some confusion of the meaning
   of a "Historic" classification.  It does NOT necessarily mean that
   the protocol is not being used.  A good example of this concept is
   the Routing Information Protocol(RIP) version 1.  There are many
   thousands of sites using this protocol even though it has Historic
   status.  There are potentially hundreds of otherwise classified RFC's
   that should be reclassified.

2.0.  Methodology

   To perform this study, each class of IETF standards are investigated
   in order of maturity:  Full, Draft, and Proposed, as well as
   Experimental.  Informational and BCP RFCs are not addressed.  RFCs
   that have been obsoleted by either newer versions or because they
   have transitioned through the standards process are not covered.
   RFCs which have been classified as Historic are also not included.

   Please note that a side effect of this choice of methodology is that
   some protocols that are defined by a series of RFC's that are of
   different levels of standards maturity are covered in different spots
   in the document.  Likewise, other natural groupings (i.e., MIBs, SMTP
   extensions, IP over FOO, PPP, DNS, etc.) could easily be imagined.

2.1.  Scope

   The procedure used in this investigation is an exhaustive reading of
   the applicable RFC's.  This task involves reading approximately
   25,000 pages of protocol specifications.  To compound this, it was
   more than a process of simple reading.  It was necessary to attempt
   to understand the purpose and functionality of each protocol in order
   to make a proper determination of IPv4 reliability.  The author has
   made every effort to produce as complete a document set as possible,
   but it is likely that some subtle (or perhaps not so subtle)
   dependence was missed.  The author encourages those familiar
   (designers, implementers or anyone who has an intimate knowledge)
   with any protocol to review the appropriate sections and make
   comments.

3.0.  Summary of Results

   In the initial survey of RFCs, 173 positives were identified out of a
   total of 877, broken down as follows:

         Standards:                        30 out of  68 or 44.12%
         Draft Standards:                  16 out of  68 or 23.53%
         Proposed Standards:               98 out of 597 or 16.42%
         Experimental RFCs:                29 out of 144 or 20.14%

   Of those identified, many require no action because they document
   outdated and unused protocols, while others are active document
   protocols being updated by the appropriate working groups (SNMP MIBs
   for example).

   Additionally, there are many instances of standards that should be
   updated but do not cause any operational impact (STD 3/RFCs 1122 and
   1123 for example) if they are not updated.

   In this statistical survey, a positive is defined as a RFC containing
   an IPv4 dependency, regardless of context.

3.1.  Application Area Specifications

   In the initial survey of RFCs, 34 positives were identified out of a
   total of 257, broken down as follows:

         Standards:                         1 out of  20 or  5.00%
         Draft Standards:                   4 out of  25 or 16.00%
         Proposed Standards:               19 out of 155 or 12.26%
         Experimental RFCs:                10 out of  57 or 17.54%

   For more information, please look at [1].

3.2.  Internet Area Specifications

   In the initial survey of RFCs, 52 positives were identified out of a
   total of 186, broken down as follows:

         Standards:                        17 out of  24 or 70.83%
         Draft Standards:                   6 out of  20 or 30.00%
         Proposed Standards:               22 out of 111 or 19.91%
         Experimental RFCs:                 7 out of  31 or 22.58%

   For more information, please look at [2].

3.3.  Operations and Management Area Specifications

   In the initial survey of RFCs, 36 positives were identified out of a
   total of 153, broken down as follows:

         Standards:                         6 out of  15 or 40.00%
         Draft Standards:                   4 out of  15 or 26.67%
         Proposed Standards:               26 out of 112 or 23.21%
         Experimental RFCs:                 0 out of  11 or  0.00%

   For more information, please look at [3].

3.4.  Routing Area Specifications

   In the initial survey of RFCs, 23 positives were identified out of a
   total of 46, broken down as follows:

         Standards:                         3 out of  3 or 100.00%
         Draft Standards:                   1 out of  3 or  33.33%
         Proposed Standards:               13 out of 29 or  44.83%
         Experimental RFCs:                 6 out of 11 or  54.54%

   For more information, please look at [4].

3.5.  Security Area Specifications

   In the initial survey of RFCs, 4 positives were identified out of a
   total of 124, broken down as follows:

         Standards:                         0 out of   1 or  0.00%
         Draft Standards:                   1 out of   3 or 33.33%
         Proposed Standards:                1 out of 102 or  0.98%
         Experimental RFCs:                 2 out of  18 or 11.11%

   For more information, please look at [5].

3.6.  Sub-IP Area Specifications

   In the initial survey of RFCs, 0 positives were identified out of a
   total of 7, broken down as follows:

         Standards:                         0 out of  0 or  0.00%
         Draft Standards:                   0 out of  0 or  0.00%
         Proposed Standards:                0 out of  6 or  0.00%
         Experimental RFCs:                 0 out of  1 or  0.00%

   For information about the Sub-IP Area standards, please look at [6].

3.7.  Transport Area Specifications

   In the initial survey of RFCs, 24 positives were identified out of a
   total of 104, broken down as follows:

         Standards:                         3 out of  5 or 60.00%
         Draft Standards:                   0 out of  2 or  0.00%
         Proposed Standards:               17 out of 82 or 20.73%
         Experimental RFCs:                 4 out of 15 or 26.67%

   For more information, please look at [7].

4.0.  Discussion of "Long Term" Stability of Addresses on Protocols

   In attempting this analysis, it was determined that a full scale
   analysis is well beyond the scope of this document.  Instead, a short
   discussion is presented on how such a framework might be established.

   A suggested approach would be to do an analysis of protocols based on
   their overall function, similar (but not strictly) to the OSI network
   reference model.  It might be more appropriate to frame the
   discussion in terms of the different Areas of the IETF.

   The problem is fundamental to the overall architecture of the
   Internet and its future.  One of the stated goals of the IPng (now
   IPv6) was "automatic" and "easy" address renumbering.  An additional
   goal is "stateless autoconfiguration."  To these ends, a substantial
   amount of work has gone into the development of such protocols as
   DHCP and Dynamic DNS.  This goes against the Internet age-old "end-
   to-end principle."

   Most protocol designs implicitly count on certain underlying
   principles that currently exist in the network.  For example, the
   design of packet switched networks allows upper level protocols to
   ignore the underlying stability of packet routes.  When paths change
   in the network, the higher level protocols are typically unaware and
   uncaring.  This works well since whether the packet goes A-B-C-D-E-F
   or A-B-X-Y-Z-E-F is of little consequence.

   In a world where endpoints (i.e., A and F in the example above)
   change at a "rapid" rate, a new model for protocol developers should
   be considered.  It seems that a logical development would be a change
   in the operation of the Transport layer protocols.  The current model
   is essentially a choice between TCP and UDP, neither of which
   provides any mechanism for an orderly handoff of the connection if
   and when the network endpoint (IP) addresses change.  Perhaps a third
   major transport layer protocol should be developed, or perhaps
   updated TCP and UDP specifications that include this function might
   be a better solution.

   There are many, many variables that would need to go into a
   successful development of such a protocol.  Some issues to consider
   are: timing principles; overlap periods as an endpoint moves from
   address A, to addresses A and B (answers to both), to only B; delays
   due to the recalculation of routing paths, etc...

5.0.  Security Considerations

   This memo examines the IPv6-readiness of specifications; this does
   not have security considerations in itself.

6.0.  Acknowledgements

   The authors would like to acknowledge the support of the Internet
   Society in the research and production of this document.
   Additionally the author, Philip J. Nesser II, would like to thanks
   his partner in all ways, Wendy M. Nesser.

   The editor, Andreas Bergstrom, would like to thank Pekka Savola for
   guidance and collection of comments for the editing of this document.
   He would further like to thank Alan E. Beard, Jim Bound, Brian
   Carpenter, and Itojun for valuable feedback on many points of this
   document.

7.0.  References

7.1.  Normative References

   [1]  Sofia, R. and P. Nesser, II, "Survey of IPv4 Addresses in
        Currently Deployed IETF Application Area Standards", RFC 3795,
        June 2004.

   [2]  Mickles, C., Editor and P. Nesser, II, "Survey of IPv4 Addresses
        in Currently Deployed IETF Internet Area Standards", RFC 3790,
        June 2004.

   [3]  Nesser, II, P. and A. Bergstrom, Editor, "Survey of IPv4
        Addresses in Currently Deployed IETF Operations & Management
        Area Standards", RFC 3796, June 2004.

   [4]  Olvera, C. and P. Nesser, II, "Survey of IPv4 Addresses in
        Currently Deployed IETF Routing Area Standards", RFC 3791, June
        2004.

   [5]  Nesser, II, P. and A. Bergstrom, Editor, "Survey of IPv4
        Addresses in Currently Deployed IETF Security Area Standards",
        RFC 3792, June 2004.

   [6]  Nesser, II, P. and A. Bergstrom, Editor, "Survey of IPv4
        Addresses in Currently Deployed IETF Sub-IP Area Standards", RFC
        3793, June 2004.

   [7]  Nesser, II, P. and A. Bergstrom, Editor, "Survey of IPv4
        Addresses in Currently Deployed IETF Transport Area Standards",
        RFC 3794, June 2004.

8.0.  Authors' Addresses

   Please contact the authors with any questions, comments or
   suggestions at:

   Philip J. Nesser II
   Principal
   Nesser & Nesser Consulting
   13501 100th Ave NE, #5202
   Kirkland, WA 98034

   Phone:  +1 425 481 4303
   Fax:    +1 425 482 9721
   EMail:  phil@nesser.com


   Andreas Bergstrom, Editor
   Ostfold University College
   Rute 503 Buer
   N-1766 Halden
   Norway

   EMail: andreas.bergstrom@hiof.no

9.0.  Full Copyright Statement

   Copyright (C) The Internet Society (2004).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at ietf-
   ipr@ietf.org.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

AI ELI5

On this page
PROBLEMThe Internet was built on IPv4 addressing, and thousands of IETF specifications depend on it. Before transitioning to IPv6, engineers needed to know exactly where those dependencies existed.
MECHANISMThe v6ops working group systematically read approximately 25,000 pages of IETF standards and documented every place IPv4 addresses are assumed or required, organizing findings by IETF area.
A ROADMAP FOR TRANSITIONThe project identified 173 RFCs out of 877 surveyed with IPv4 dependencies (about 20%), showing that the transition challenge was significant but not universal. These companion documents in seven areas guided protocol updates.

§1Why Survey IPv4 Dependencies

RFC 3789 introduces a large project: documenting all uses of IPv4 addresses in the IETF standards track and experimental RFCs. The driving force is the inevitable transition from IPv4 to IPv6. As IPv4 address space became exhausted and the Internet grew to billions of devices, IPv6 became necessary. But many protocols, designed before the transition was planned, assumed IPv4 addresses would always be available.

The survey is an exhaustive reading of approximately 25,000 pages of specification text. It attempts to understand not just where IPv4 appears, but why it appears and whether a protocol truly depends on IPv4 or could work address-independently.

There are thousands of rules for how the Internet works, and most were written when there was only one kind of address. Someone needs to read all of them and mark which ones need to change for the new addresses.

§2The History of Address Exhaustion

IPv4 was originally designed with 8-bit network and 24-bit host addresses, as documented in RFC 760. In 1983, it was updated to introduce the familiar A, B, C, D, and E class system. Over the following decades, clever engineering extended the life of IPv4: subnetting (RFC 917, 1984), classless inter-domain routing (CIDR) in the early 1990s, and network address translation (NATs). But each solution masked the underlying reality that IPv4's 4.3 billion addresses could not scale to a global network of hundreds of billions of devices.

By the early 1990s, the IETF began designing IPv6, which offers 128-bit addresses and was intended to be automatically configurable and address-independent where possible. The challenge: thousands of existing protocols would need to be redesigned or at least updated to support both IPv4 and IPv6 during the transition.

The old address system works fine for millions of computers, but the Internet grew way bigger than anyone expected. Engineers patched it up several times, but eventually they had to design completely new addresses for the whole system.

§3How the Survey Was Conducted

The investigators examined IETF standards in order of maturity: Full Standards (61 documents), Draft Standards (68 documents), Proposed Standards (597 documents), and Experimental RFCs (144 documents). They deliberately excluded Informational RFCs, Best Current Practices, and Historic standards, focusing on active standards that might still need updates. A total of 877 RFCs were examined.

The methodology took an exhaustive approach: reading the actual RFC text, not just abstracts or titles. For each RFC, the team determined whether it actually depends on IPv4 as part of its core function or merely documents an IPv4-specific protocol that could be redesigned. Some protocols—like DNS or DHCP—had clear IPv4 dependencies but also clear paths to support IPv6.

They picked a big pile of rules, read every word carefully to see which ones mention old-style addresses, and sorted them by how official and widely-used each rule is.

§4Key Findings Across All Areas

The initial survey identified 173 RFCs with IPv4 dependencies out of 877 total (19.7%). The breakdown showed that Full Standards had the highest percentage of IPv4 dependencies (30 out of 68, or 44%), which makes sense because they are mature, widely deployed protocols that were designed decades ago. Draft Standards had 23.5% with dependencies (16 out of 68), while Proposed Standards had only 16.4% (98 out of 597).

Results varied dramatically by IETF area. The Internet Area (which includes protocols like IP itself, DNS, and DHCP) had 52 positives out of 186 RFCs (28%). The Routing Area had 23 out of 46 (50%), because nearly every routing protocol was designed for IPv4. The Security Area had only 4 out of 124 (3%), while the Sub-IP Area had zero dependencies. This variation indicated that some areas of the Internet needed much more work than others for the transition.

Out of about 900 rules, roughly 170 mention old addresses. The rules used the most—the oldest and most popular ones—mention old addresses almost half the time. Newer ideas and security rules rarely mention them.

§5The Long-Term Challenge

Beyond the immediate task of cataloging dependencies, the survey raised a deeper question: how should protocols be designed so that future address transitions are not traumatic? The current Internet model relies on a few principles: the End-to-End principle (applications should not depend on the network layer), stateless autoconfiguration (devices should be able to configure themselves), and orderly renumbering (when a site changes IP address block, all its devices should adapt smoothly).

However, most current transport-layer protocols (TCP and UDP) provide no mechanism for a connection to survive if one endpoint's address changes. This works today because addresses are relatively stable, but it suggests that future protocol designs should consider address independence earlier. The document notes that DHCP and Dynamic DNS attempt to address this but represent a departure from the original End-to-End principle.

Changing addresses for the whole Internet is very hard. In the future, maybe the rules should be designed so that if a computer gets a new address, it doesn't break all its conversations.

§6References