





Network Working Group                                           P. Gross
Request for Comments: 1380                                    IESG Chair
                                                             P. Almquist
                                                        IESG Internet AD
                                                           November 1992


              IESG Deliberations on Routing and Addressing

Status Of This Memo

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

Abstract

   This memo summarizes issues surrounding the routing and addressing
   scaling problems in the IP architecture, and it provides a brief
   background of the ROAD group and related activities in the Internet
   Engineering Task Force (IETF).

   It also provides a preliminary report of the Internet Engineering
   Steering Group (IESG) deliberations on how these routing and
   addressing issues should be pursued in the Internet Architecture
   Board (IAB)/IETF.

Acknowledgements

   This note draws principally from two sources: the output from the
   ROAD group, as reported at the San Diego IETF meeting, and on
   numerous detailed discussions in the IESG following the San Diego
   IETF meeting.  Zheng Wang, Bob Hinden, Kent England, and Bob Smart
   provided input for the "Criteria For Bigger Internet Addresses"
   section below.  Greg Vaudreuil prepared the final version of the
   bibliography, based on previous bibliographies by Lyman Chapin and
   bibliographies distributed on the Big-Internet mailing list.

Table of Contents

   1. INTRODUCTION..................................................  2
   2.  ISSUES OF GROWTH AND EVOLUTION IN THE INTERNET...............  3
   2.1  The Problems................................................  3
   2.2  Possible Solutions..........................................  5
   3. PREPARING FOR ACTION..........................................  7
   3.1 The IAB Architecture Retreats................................  7
   3.2 The Santa Fe IETF............................................  7
   3.3 The ROAD Group and beyond....................................  8



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   4. SETTING DIRECTIONS FOR THE IETF............................... 10
   4.1 The Need For Interim Solutions............................... 10
   4.2 The Proposed Phases.......................................... 10
   4.3 A Solution For Routing Table Explosion -- CIDR............... 12
   4.4 Regarding "IP Address Exhaustion"............................ 13
   4.5 Milestones And Timetable For Making a Recommendation for
       "Bigger Internet Addresses".................................. 14
   5. SUMMARY....................................................... 15
   Appendix A. FOR MORE INFORMATION................................. 16
   Appendix B. INFORMATION AND SELECTION CRITERIA FOR "BIGGER
               INTERNET ADDRESSES".................................. 16
   Appendix C. BIBLIOGRAPHY......................................... 20
   Security Considerations.......................................... 21
   Authors' Addresses............................................... 22

1. INTRODUCTION

   It seems unlikely that the designers of IP ever imagined at the time
   what phenomenal success the Internet would achieve.  Internet
   connections were initially intended primarily for mainframe computers
   at sites performing DARPA-sponsored research.  Now, of course, the
   Internet has extended its reach to the desktop and is beginning to
   extend into the home.  No longer the exclusive purview of pure R&D
   establishments, the Internet has become well entrenched in parts of
   the corporate world and is beginning to make inroads into secondary
   and even primary schools.  While once it was an almost exclusively
   U.S. phenomenon, the Internet now extends to every continent and
   within a few years may well include network connections in every
   country.

   Over the past couple of years, we have seen increasingly strong
   indications that all of this success will stress the limits of IP
   unless appropriate corrective actions are taken.  The supply of
   unallocated Class B network numbers is rapidly dwindling, and the
   amount of routing information now carried in the Internet is
   increasingly taxing the abilities of both the routers and the people
   who have to manage them.  Somewhat longer-term, it is possible that
   we will run out of host addresses or network numbers altogether.

   While these problems could be avoided by attempting to restrict the
   growth of the Internet, most people would prefer solutions that allow
   growth to continue.  Fortunately, it appears that such solutions are
   possible, and that, in fact, our biggest problem is having too many
   possible solutions rather than too few.

   This memo provides a preliminary report of IESG deliberations on how
   routing and addressing issues can be pursued in the IAB/IETF.




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   In following sections, we will discuss in more detail the problems
   confronting us and possible approaches.  We will give a brief
   overview of the ROAD group and related activities in the IETF.  We
   will then discuss possible courses of action in the IETF.
   Ultimately, the IESG will issue a recommendation from the IESG/IETF
   to the IAB.

2.  ISSUES OF GROWTH AND EVOLUTION IN THE INTERNET

2.1  The Problems

   The Internet now faces three growth-related problems:

     - Class B network number exhaustion - Routing table explosion
     - IP address space exhaustion

2.1.1  Class B Network Number Exhaustion

   Over the last several years, the number of network numbers assigned
   and the number of network numbers configured into the Merit NSFnet
   routing database have roughly doubled every 12 months.  This has led
   to estimates that, at the current allocation rate, and in the absence
   of corrective measures, it will take less than 2 years to allocate
   all of the currently unassigned Class B network numbers.

   After that, new sites which wished to connect more than the number of
   hosts possible in a single Class C (253 hosts) would need to be
   assigned multiple Class C networks.  This will exacerbate the routing
   table explosion problems described next.

2.1.2.  Routing Table Explosion

   As the number of networks connected to the Internet has grown, the
   amount of routing information that has to be passed around to keep
   track of them all is likewise growing.  This is leading to two types
   of problems.

Hardware and Protocol Limits

   Routing protocols must pass around this information, and routers must
   store and use it.  This taxes memory limits in the routers, and can
   also consume significant bandwidth when older routing protocols are
   used, (such as EGP and RIP, which were designed for a much smaller
   number of networks).

   The limits on the memory in the routers seem to be the most pressing.
   It is already the case that the routers used in the MILNET are
   incapable of handling all of the current routes, and most other



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   service providers have found the need to periodically upgrade their
   routers to accommodate ever larger quantities of routing information.
   An informal survey of router vendors by the ROAD group estimated that
   most of the currently deployed generation of high-end routers will
   support O(16000) routes.  This will be probably be adequate for the
   next 12 to 18 months at the current rate of growth.  Most vendors
   have begun, or will soon begin, to ship routers capable of handling
   O(64000) routes, which should be adequate for an additional two years
   if the above Class B Network Number Exhaustion problem is solved.

Human Limits

   The number of routes does not merely tax the network's physical
   plant.  Network operators have found that the inter-domain routing
   protocol mechanisms often need to be augmented by a considerable
   amount of configuration to make the paths followed by packets be
   consistent with the policies and desires of the network operators.
   As the number of networks increases, the configuration (and the
   traffic monitoring to determine whether the configuration has been
   done correctly) becomes increasingly difficult and time-consuming.

   Although it is not possible to determine a number of networks (and
   therefore a time frame) where human limits will be exceeded, network
   operators view this as a significant short-term problem.

2.1.3.  IP Address Exhaustion

   If the current exponential growth rate continues unabated, the number
   of computers connected to the Internet will eventually exceed the
   number of possible IP addresses.  Because IP addresses are divided
   into "network" and "host" portions, we may not ever fully run out of
   IP addresses because we will run out of IP network numbers first.

   There is considerable uncertainty regarding the timeframe when we
   might exceed the limits of the IP address space.  However, the issue
   is serious enough that it deserves our earliest attention.  It is
   very important that we develop solutions to this potential problem
   well before we are in danger of actually running out of addresses.

2.1.4.  Other Internetwork Layer Issues

   Although the catalog of problems above is pretty complete as far as
   the scaling problems of the Internet are concerned, there are other
   Internet layer issues that will need to be addressed over the coming
   years.  These are issues regarding advanced functionality and service
   guarantees in the Internet layer.

   In any attempt to resolve the Internet scaling problems, it is



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   important to consider how these other issues might affect the future
   evolution of Internet layer protocols.  These issues include:

        1)   Policy-based routing
        2)   Flow control
        3)   Weak Quality-of-Service (QOS)
        4)   Service guarantees (strong QOS)
        5)   Charging

2.2  Possible Solutions

2.2.1.  Class B Network Number Exhaustion

   A number of approaches have been suggested for how we might slow the
   exhaustion of the Class B IP addresses.  These include:

      1)   Reclaiming those Class B network numbers which have been
      assigned but are either unused or used by networks which are not
      connected to the Internet.

      2)   Modifying address assignment policies to slow the assignment
      of Class B network numbers by assigning multiple Class C network
      numbers to organizations which are only a little bit to big to be
      accommodated by a Class C network number.

         Note: It is already the case that a Class B number is assigned
         only if the applicant would need more than "several" Class C
         networks.  The value of "several" has increased over time from
         1 to (currently) 32.

      3)   Use the Class C address space to form aggregations of
      different size than the normal normal Class C addresses.  Such
      schemes include Classless Inter-Domain Routing (CIDR) [Fuller92]
      and the C# scheme [Solen92].

2.2.2.  Routing Table Explosion

   As was described earlier, there are actually two parts to this
   problem.  They each have slightly different possible approaches:

Hardware and Protocol Limits

      1) More thrust.  We could simply recognize the fact that routers
      which need full Internet routing information will require large
      amounts of memory and processing capacity.  This is at best a very
      short-term approach, and we will always need to face this problem
      in the long-term.




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      2) Route servers (a variant of the "More Thrust" solution).
      Instead of requiring every router to store complete routing
      information, mechanisms could be developed to allow the tasks of
      computing and storing routes to be offloaded to a server.  Routers
      would request routes from the server as needed (presumably caching
      to improve performance).

      3) Topology engineering.  Many network providers already try to
      design their networks in such a way that only a few of the routers
      need complete routing information (the others rely on default
      routes to reach destinations that they don't have explicit routes
      to).  While this is inconvenient for network operators, it is a
      trend which is likely to continue.

      It is also the case that network providers could further reduce
      the number of routers which need full routing information by
      accepting some amount of suboptimal routing or reducing alternate
      paths used for backup.

      4) Charging-based solutions.  By charging for network number
      advertisements, it might be possible to discourage sites from
      connecting more networks to the Internet than they get significant
      value from having connected.

      5) Aggregation of routing information.  It is fairly clear that in
      the long-term it will be necessary for addresses to be more
      hierarchical.  This will allow routes to many networks to be
      collapsed into a single summary route.  Therefore, an important
      question is whether aggregation can also be part of the short-term
      solution.  Of the proposals to date, only CIDR could provide
      aggregation in the short-term.  All longer-term proposals should
      aggregation.

Human Limits

      1) Additional human resources.  Network providers could devote
      additional manpower to routing management, or accept the
      consequences of a reduced level of routing management.  This is
      obviously unattractive as anything other than a very short-term
      solution.

      2) Better tools.  Network operators and router vendors could work
      to develop more powerful paradigms and mechanisms for routing
      management.

      The IETF has already undertaken some work in the areas of route
      filtering and route leaking.




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2.2.3.  IP Address Exhaustion

   The following general approaches have been suggested for dealing with
   the possible exhaustion of the IP address space:

      1) Protocol modifications to provide a larger address space.  By
      enhancing IP or by transitioning to another protocol with a larger
      address space, we could substantially increase the number of
      available network numbers and addresses.

      2) Addresses which are not globally unique.  Several proposed
      schemes have emerged whereby a host's domain name is globally
      unique, but its IP address would be unique only within it's local
      routing domain.  These schemes usually involve address translating

      3) Partitioned Internet.  The Internet could be partitioned into
      areas, such that a host's IP address would be unique only within
      its own area.  Such schemes generally postulate application
      gateways to interconnect the areas.  This is not unlike the
      approach often used to connect differing protocol families.

      4) Reclaiming network numbers.  Network numbers which are not
      used, or are used by networks which are not connected to the
      Internet, could conceivably be reclaimed for general Internet use.
      This isn't a long-term solution, but could possibly help in the
      interim if for some reason address exhaustion starts to occur
      unexpectedly soon.

3. PREPARING FOR ACTION

3.1 The IAB Architecture Retreats

   In July 1991, the IAB held a special workshop to consider critical
   issues in the IP architecture (Clark91).  Of particular concern were
   the problems related to Internet growth and scaling.  The IAB felt
   the issues were of sufficient concern to begin organizing a special
   group to explore the issues and to explore possible solutions.  Peter
   Ford (LANL) was asked to organize this effort.  The IAB reconvened
   the architecture workshop in January 1992 to further examine these
   critical issues, and to meet jointly with the then-formed ROAD group
   (see below).

3.2 The Santa Fe IETF

   At the November 1991 Santa Fe IETF meeting, the BGP Working Groups
   independently began a concerted exploration of the issues of routing
   table scaling.  The principal approach was to perform route
   aggregation by using address masks in BGP to do "supernetting"



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   (rather than "subnetting").  This approach would eventually evolve
   into CIDR.  The BGP WG decided to form a separate subgroup, to be led
   by Phill Gross (ANS) to pursue this solution.

3.3 The ROAD Group and Beyond

   At the Santa Fe IETF, the initially separate IAB and BGP WG
   activities were combined into a special effort, named the "ROuting
   and ADdressing (ROAD) Group", to be co-chaired by Ford and Gross.

   The group was asked to explore possible near-term approaches for the
   scaling problems described in the last section, namely:

       - Class B address exhaustion
       - Routing table explosion
       - IP address space exhaustion

   The ROAD group was asked to report back to the IETF at the San Diego
   IETF (March 1992).  Suggested guidelines included minimizing changes
   to hosts, must be incrementally deployable, and must provide support
   for a billion networks.

   The ROAD group was not a traditional open IETF working group.  It was
   always presumed that this was a one-time special group that would
   lead to the formation of other IETF WGs after its report in San
   Diego.

   The ROAD group held several face-face meetings between the November
   1991 (Santa Fe) and March 1992 (San Diego) IETF meetings.  This
   included several times at the Santa Fe IETF meeting, December 1991 in
   Reston VA, January 1992 in Boston (in conjunction with the IAB
   architecture workshop), and January 1992 in Arizona).  There was also
   much discussion by electronic mail.

   The group produced numerous documents, which have variously been made
   available as Internet-Drafts or RFCs (see Bibliography in Appendix
   D).

   As follow-up, the ROAD co-chairs reported to the IETF plenary in
   March 1992 in San Diego.  Plus, several specific ROAD-related
   activities took place during the IETF meeting that week.

   The Ford/Gross presentation served as a preliminary report from the
   ROAD group.  The basic thrust was:

      1.  The Internet community needs a better way to deal with current
      addresses (e.g., hierarchical address assignments for routing
      aggregation to help slow Class B exhaustion and routing table



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      explosion).  Classless Inter-Domain Routing (CIDR; also called
      "supernetting") was recommended.  CIDR calls for:

        - The development of a plan for hierarchical IP address
          assignment for aggregation in routing,

        - Enhanced "classless" Inter-domain protocols (i.e., carry
          address masks along with IP addresses),

        - Inter-Domain routing "Usage documents" for using addressing
          and routing plan with the enhanced inter-domain protocols,
          and for interacting with IGPs.

      2.  The Internet community needs bigger addresses for the Internet
      to stem IP address exhaustion.  The ROAD group explored several
      approaches in some depth.  Some of these approaches were discussed
      at the San Diego IETF.  However, a final recommendation of a
      single approach did not emerge.

      3.  The Internet community needs to focus more effort on future
      directions for Internet routing and advanced Internet layer
      features.

   Other ROAD-related activities at the San Diego IETF meeting included:

      - Monday,  8:00 - 9:00 am,  Report from the ROAD group on
      "Internet Routing and Addressing Considerations",

      - Monday,  9:30-12:00pm,  Geographical Addressing and Routing
      (during NOOP WG session),

      - Monday,  1:30-3:30pm,  Preliminary discussion of a CIDR routing
      and addressing plan  (during ORAD session),

      - Tuesday,  1:30-6:00pm,  Internet Routing and Addressing BOF (to
      discuss ROAD results and to explore approaches for bigger Internet
      address space),

      - Wednesday,  1:30-3:30pm,  CIDR Supernetting BOF (joint with BGP
      WG),

      - Thursday,  4:00-6:00pm,  Summary of ROAD activities in San Diego
      followed by open plenary discussion.

   The slides for the Monday presentation (Ford92), slides for the
   Thursday summary (and notes in the Chair's message) (Gross92), and
   notes for the other sessions are contained in the Proceedings of the
   Twenty-Third IETF (San Diego).



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4. SETTING DIRECTIONS FOR THE IETF

4.1 The Need For Interim Solutions

   Solutions to the problems of advanced Internet layer functionality
   are far from being well understood.  While we should certainly
   encourage research in these areas, it is premature to start an
   engineering effort for an Internet layer which would solve not only
   the scaling problems but also those other issues.

   Plus, most approaches to the problem of IP address space exhaustion
   involve changes to the Internet layer.  Such approaches mean changes
   changes to host software that will require us to face the very
   difficult transition of a large installed base.

   It is therefore not likely that we can (a) develop a single solution
   for the near-term scaling problems that will (b) also solve the
   longer-term problems of advanced Internet-layer functionality, that
   we can (c) choose, implement and deploy before the nearer-term
   problems of Class B exhaustion or routing table explosion confront
   us.

   This line of reasoning leads to the inevitable conclusion that we
   will need to make major enhancements to IP in (at least) two stages.

   Therefore, we will consider interim measures to deal with Class B
   address exhaustion and routing table explosion (together), and to
   deal with IP address exhaustion (separately).

   We will also suggest that the possible relation between these nearer-
   term measures and work toward advanced Internet layer functionality
   should be made an important consideration.

4.2 The Proposed Phases

   The IESG recommends that we divide the overall course of action into
   several phases.  For lack of a better vocabulary, we will term these
   "immediate", "short-term", mid-term", and "long-term" phases.  But,
   as the ROAD group pointed out, we should start all the phases
   immediately. We cannot afford to act on these phases consecutively!

   In brief, the phases are:

    - "Immediate".  These are configuration and engineering actions that
   can take place immediately without protocol design, development, or
   deployment.  There are a number of actions that can begin
   immediately.  Although none of these will solve any of the problems,
   they can help slow the onset of the problems.



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   The IESG specifically endorses:

       1) the need for more conservative address assignment
          policies,
       2) alignment of new address assignment policies with any new
          aggregation schemes,
       3) efforts to reclaim unused Class B addresses,
       4) installation of more powerful routers by network operators
          at key points in the Internet, and
       5) careful attention to topology engineering.

    - "Short-term".  Actions in this phase are aimed at dealing with
   Class B exhaustion and routing table explosion.  These problems are
   deemed to be quite pressing and to need solutions well before the IP
   address exhaustion problem needs to be or could be solved.  In this
   timeframe, changes to hosts can *not* be considered.

    - "Mid-term".  In the mid-term, the issue of IP address exhaustion
   must be solved.  This is the most fundamental problem facing the IP
   architecture.  Depending on the expected timeframe, changes to host
   software could be considered.  Note: whatever approach is taken, it
   must also deal with the routing table explosion.  If it does not,
   then we will simply be forced to deal with that problem again, but in
   a larger address space.

    - "Long-term".  Taking a broader view, the IESG feels that advanced
   Internet layer functionality, like QOS support and  resource
   reservation, will be crucial to the long-term success of the Internet
   architecture.

   Therefore, planning for advanced Internet layer functionality should
   play a key role in our choice of mid-term solutions.

   In particular, we need to keep several things in mind:

      1) The long-term solution will require replacement and/or
      extension of the Internet layer.  This will be a significant
      trauma for vendors, operators, and for users.  Therefore, it is
      particularly important that we either minimize the trauma involved
      in deploying the sort-and mid-term solutions, or we need to assure
      that the short- and mid-term solutions will provide a smooth
      transition path for the long-term solutions.

      2) The long-term solution will likely require globally unique
      endpoint identifiers with an hierarchical structure to aid
      routing.  Any effort to define hierarchy and assignment mechanisms
      for short- or mid-term solutions would, if done well, probably
      have long-term usefulness, even if the long-term solution uses



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      radically different message formats.

      3) To some extent, development and deployment of the interim
      measures will divert resources away from other important projects,
      including the development of the long-term solution.  This
      diversion should be carefully considered when choosing which
      interim measures to pursue.

4.3  A Solution For Routing Table Explosion -- CIDR

   The IESG accepted ROAD's endorsement of CIDR [Fuller92].  CIDR solves
   the routing table explosion problem (for the current IP addressing
   scheme), makes the Class B exhaustion problem less important, and
   buys time for the crucial address exhaustion problem.

   The IESG felt that other alternatives (e.g., C#, see Solen92) did not
   provide both routing table aggregation and Class B conservation at
   comparable effort.

   CIDR will require policy changes, protocol specification changes,
   implementation, and deployment of new router software, but it does
   not call for changes to host software.

   The IESG recommends the following course of action to pursue CIDR in
   the IETF:

      a. Adopt the CIDR model described in Fuller92.

      b. Develop a plan for "IP Address Assignment Guidelines".

      The IESG considered the creation of an addressing plan to be an
      operational issue.  Therefore, the IESG asked Bernhard Stockman
      (IESG Operational Requirements Area Co-Director) to lead an effort
      to develop such a plan.  Bernhard Stockman is in a position to
      bring important international input (Stockman92) into this effort
      because he is a key player in RIPE and EBONE and he is a co-chair
      of the Intercontinental Engineering Planning Group (IEPG).

      A specific proposal [Gerich92] has now emerged.  [Gerich92]
      incorporates the views of the IETF, RIPE, IEPG, and the Federal
      Engineering Planning group (FEPG).

      c. Pursue CIDR extensions to BGP in the BGP WG.

      This activity stated at the San Diego IETF meeting.  A new BGP
      specification, BGP4, incorporating the CIDR extensions, is now
      available for public comment [Rekhter92a].




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      d. Form a new WG to consider CIDR-related extensions to IDRP
      (e.g., specify how run IDRP for IP inter-domain routing).

      e. Give careful consideration to how CIDR will be deployed in the
      Internet.

      This includes issues such as how to maintain address aggregation
      across non-CIDR domains and how CIDR and various IGPs will need to
      interact.  Depending on the status of the combined CIDR
      activities, the IESG may recommend forming a "CIDR Deployment WG",
      along the same lines as the current BGP Deployment WG.

4.4 Regarding "Bigger Internet Addresses"

   In April-May 1992, the IESG reviewed the various approaches emerging
   from  the ROAD group activities -- e.g., "Simple CLNP" [Callon92a],
   "IP Encaps"  [Hinden92], "CNAT" [Callon92b], and "Nimrod"
   [Chiappa91].

   (Note: These were the only proposals under serious consideration in
   this time period.  Other proposals, namely "The P Internet Protocol
   (PIP)" [Tsuchiya92b] and "The Simple Internet Protocol (SIP)"
   [Deering92] have since been proposed.  Following the San Diego IETF
   deliberations in March, "Simple CLNP" evolved into "TCP and UDP with
   Bigger Addresses (TUBA)", and "IP Encaps" evolved into "IP Address
   Encapsulation (IPAE)" [Hinden92].)

   The "Simple CLNP" approach perhaps initially enjoyed more support
   than other approaches.

   However, the consensus view in the IESG was that the full impact of
   transition to "Simple CLNP" (or to any of the proposed approaches)
   had not yet been explored in sufficient detail to make a final
   recommendation possible at this time.

   The feeling in the IESG was that such important issues as

      - impact on operational infrastructure,
      - impact on current protocols (e.g., checksum computation
        in TCP and UDP under any new IP-level protocol),
      - deployment of new routing protocols,
      - assignment of new addresses,
      - impact on performance,
      - ownership of change control
      - effect of supporting new protocols, such as for address
        resolution,
      - effect on network management and security, and
      - the costs to network operators and network users who must



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        be trained in the architecture and specifics of any  new
        protocols needed to be explored in more depth before a
        decision of this magnitude should be made.

   At first the question seemed to be one of timing.

   At the risk of oversimplifying some very wide ranging discussions,
   many in the IESG felt that if a decision had to be made
   *immediately*, then "Simple CLNP" might be their choice.  However,
   they would feel much more comfortable if more detailed information
   was part of the decision.

   The IESG felt there needed to be an open and thorough evaluation of
   any proposed new routing and addressing architecture.  The Internet
   community must have a thorough understanding of the impact of
   changing from the current IP architecture to a new one.  The
   community needs to be confident that we all understand which approach
   has the most benefits for long-term internet growth and evolution,
   and the least impact on the current Internet.

   The IESG considered what additional information and criteria were
   needed to choose between alternative approaches.  We also considered
   the time needed for gathering this additional information and the
   amount of time remaining before it was absolutely imperative to make
   this decision (i.e., how much time do we have before we are in danger
   of running out of IP addresses *before* we could deploy a new
   architecture?).

   This led the IESG to propose a specific set of selection criteria and
   information, and specific milestones and timetable for the decision.

   The next section describes the milestones and timetable for choosing
   the approach for bigger Internet addresses.

   The selection criteria referenced in the milestones are contained in
   Appendix B.

4.5 Milestones And Timetable For Making a Recommendation for "Bigger
    Internet Addresses"

   In June, the IESG recommended that a call for proposals be made, with
   initial activities to begin at the July IETF in Boston, and with a
   strict timetable for reaching a recommendation coming out of the
   November IETF meeting [Gross92a].

   Eventually, the call for proposals was made at the July meeting
   itself.




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   A working group will be formed for each proposed approach.  The
   charter of each WG will be to explore the criteria described in
   Appendix B and to develop a detailed plan for IESG consideration.

   The WGs will be asked to submit an Internet-Draft prior to the
   November 1992 IETF, and to make presentations at the November IETF.
   The IESG and the IETF will review all submitted proposals and then
   the IESG will make a recommendation to the IAB following the November
   1992 IETF meeting.

   Therefore, the milestones and timetable for the IESG to reach a
   recommendation on bigger Internet addresses are:

      July 1992 -- Issue a call for proposals at the Boston IETF meeting
      to form working groups to explore separate approaches for bigger
      Internet addresses.

      August-November 1992 -- Proposed WGs submit charters, create
      discussion lists, and begin their deliberations by email and/or
      face- to-face meetings.  Redistribute the IESG recommendation
      (i.e., this memo).  Public review, discussion, and modification as
      appropriate of the "selection criteria" in Appendix B.

      October 1992 -- By the end of October, each WG will be required to
      submit a written description of the approach and how the criteria
      are satisfied.  This is to insure that these documents are
      distributed as Internet-Drafts for public review well before the
      November IETF meeting.

      November 1992 -- Each WG will be given an opportunity to present
      its findings in detail at the November 1992 IETF meeting.  Based
      on the written documents, the presentations, and public
      discussions (by email and at the IETF), the IESG will forward a
      recommendation to the IAB after the November IETF meeting.

5. SUMMARY

   The problems of Internet scaling and address exhaustion are
   fundamentally important to the continued health of the global
   Internet, and to the long-term success of such programs as the U.S.
   NREN and the European EBONE.  Finding and embarking on a course of
   action is critical.  However, the problem is so important that we
   need a deep understanding of the information and criteria described
   in Appendix B before a decision is made.

   With this memo, the IESG re-affirms its earlier recommendation to the
   IAB that (a) we move CIDR forward in the IETF as described in section
   4.3, and (b) that we encourage the exploration of other proposals for



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   a bigger Internet address space according to the timetable in section
   4.5.

Appendix A.  FOR MORE INFORMATION

   To become better acquainted with the issues and/or to follow the
   progress of these activities:

       - Please see the documents in the Bibliography below.

       - Join the Big-Internet mailing list where the general issues
         are discussed (big-internet-request@munnari.oz.au).

       - Any new WG formed will have an open mailing list.  Please feel
         free to join each as they are announced on the IETF mailing
         list.  The current lists are:

          PIP:      pip-request@thumper.bellcore.com
          TUBA:     tuba-request@lanl.gov
          IPAE:     ip-encaps-request@sunroof.eng.sun.com
          SIP:      sip-request@caldera.usc.edu

       - Attend the November IETF in Washington D.C. (where the WGs
         will report and the IESG recommendation will begin formulating
         its recommendation to the IAB).

   Note: In order to receive announcements of:

       - future IETF meetings and agenda,
       - new IETF working groups, and
       - the posting of Internet-Drafts and RFCs,

   please send a request to join the IETF-Announcement mailing list
   (ietf-announce-request@nri.reston.va.us).

Appendix B.  INFORMATION AND SELECTION CRITERIA FOR "BIGGER INTERNET
             ADDRESSES"

   This section describes the information and criteria which the IESG
   felt that any new routing and addressing proposal should supply.  As
   the community has a chance to comment on these criteria, and as the
   IESG gets a better understanding of the issues relating to selection
   of a new routing and addressing architecture, this section may be
   revised and published in a separate document.

   It is expected that every proposal submitted for consideration should
   address each item below on an point-by-point basis.




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B.1  Description of the Proposed Scheme

   A complete description of the proposed routing and addressing
   architecture should be supplied.  This should be at the level of
   detail where the functionality and complexity of the scheme can be
   clearly understood.  It should describe how the proposal solves the
   basic problems of IP address exhaustion and router resource overload.

B.2  Changes Required

   All changes to existing protocols should be documented and new
   protocols which need to be developed and/or deployed should be
   specified and described.  This should enumerate all protocols which
   are not currently in widespread operational deployment in the
   Internet.

   Changes should also be grouped by the devices and/or functions they
   affect.  This should include at least the following:

         - Protocol changes in hosts
         - Protocol changes in exterior router
         - Protocol changes in interior router
         - Security and Authentication Changes
         - Domain name system changes
         - Network management changes
         - Changes required to operations tools (e.g., ping, trace-
           route, etc.)
         - Changes to operational and administration
           procedures

   The changes should also include if hosts and routers have their
   current IP addresses changed.

   The impact and changes to the existing set of TCP/IP protocols should
   be described.  This should include at a minimum:

         - IP
         - ICMP
         - DNS
         - ARP/RARP
         - TCP
         - UDP
         - FTP
         - RPC
         - SNMP

   The impact on protocols which use IP addresses as data should be
   specifically addressed.



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B.3  Implementation Experience

   A description of implementation experience with the proposal should
   be supplied.  This should include the how much of the proposal was
   implemented and hard it was to implement.  If it was implemented by
   modifying existing code, the extent of the modifications should be
   described.

B.4  Large Internet Support

   The proposal should describe how it will scale to support a large
   internet of a billion networks.  It should describe how the proposed
   routing and addressing architecture will work to support an internet
   of this size.  This should include, as appropriate, a description of
   the routing hierarchy, how the routing and addressing will be
   organized, how different layers of the routing interact (e.g.,
   interior and exterior, or L1, L2, L3, etc.), and relationship between
   addressing and routing.

   The addressing proposed should include a description of how addresses
   will be assigned, who owns the addresses (e.g., user or service
   provider), and whether there are restrictions in address assignment
   or topology.

B.5 Syntax and semantics of names, identifiers and addresses

   Proposals should address the manner in which data sources and sinks
   are identified and addressed, describe how current domain names and
   IP addresses would be used/translated/mapped in their scheme, how
   proposed new identifier and address fields and semantics are used,
   and should describe the issues involved in administration of these id
   and address spaces according to their proposal.  The deployment plan
   should address how these new semantics would be introduced and
   backward compatibility maintained.

   Any overlays in the syntax of these protocol structures should be
   clearly identified and conflicts resulting from syntactic overlay of
   functionality should be clearly addressed in the discussion of the
   impact on administrative assignment.

B.6  Performance Impact

   The performance impact of the new routing and addressing architecture
   should be evaluated.  It should be compared against the current state
   of the art with the current IP.  The performance evaluation for
   routers and hosts should include packets-per-second and memory usage
   projections, and bandwidth usage for networks.  Performance should be
   evaluated for both high speed speed and low speed lines.



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   Performance for routers (table size and computational load) and
   network bandwidth consumption should be projected based on the
   following projected data points:

      -Domains    10^3   10^4   10^5   10^6   10^7   10^8
      -Networks   10^4   10^5   10^6   10^7   10^8   10^9
      -Hosts      10^6   10^7   10^8   10^9   10^10  10^11

B.7  Support for TCP/IP hosts than do not support the new architecture

   The proposal should describe how hosts which do not support the new
   architecture will be supported -- whether they receive full services
   and can communicate with the whole Internet, or if they will receive
   limited services.  Also, describe if a translation service be
   provided between old and new hosts?  If so, where will be this be
   done.

B.8  Effect on User Community

   The large and growing installed base of IP systems comprises people,
   as well as software and machines.  The proposal should describe
   changes in understanding and procedures that are used by the people
   involved in internetworking.  This should include new and/or changes
   in concepts, terminology, and organization.

B.9  Deployment Plan Description

   The proposal should include a deployment plan.  It should include the
   steps required to deploy it.  Each step should include the devices
   and protocols which are required to change and what benefits are
   derived at each step. This should also include at each step if hosts
   and routers are required to run the current and proposed internet
   protocol.

   A schedule should be included, with justification showing that the
   schedule is realistic.

B.10  Security Impact

   The impact on current and future security plans should be addressed.
   Specifically do current security mechanisms such as address and
   protocol port filtering work in the same manner as they do today, and
   what is the effect on security and authentication schemes currently
   under development.

B.11  Future Evolution

   The proposal should describe how it lays a foundation for solving



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   emerging internet problems such as security/authentication, mobility,
   resource allocation, accounting, high packet rates, etc.

Appendix C.  BIBLIOGRAPHY

-Documents and Information from IETF/IESG:

   [Ford92] Ford, P., and P. Gross, "Routing And Addressing
   Considerations", Proceedings of the Twenty-Third IETF, March 1992.

   [Gross92] Gross, P., "Chair's Message and Minutes of the Open IETF
   Plenary", Proceedings of the Twenty-Third IETF, March 1992.

   [Gross92a] Gross, P., "IESG Deliberations on Routing and Addressing",
   Electronic mail message to the Big-Internet mailing list, June 1992.

-Documents directly resulting from the ROAD group:

   [Fuller92] Fuller, V., Li, T., Yu, J., and K. Varadhan,
   "Supernetting:  an Address Assignment and Aggregation Strategy", RFC
   1338, BARRNet, cisco, Merit, OARnet, June 1992.

   [Hinden92] Hinden, B., "New Scheme for Internet Routing and
   Addressing (ENCAPS)", Email message to Big-Internet mailing list,
   March 16, 1992.

   [Callon92a] Callon, R., "TCP and UDP with Bigger Addresses (TUBA), A
   Simple Proposal for Internet Addressing and Routing", RFC 1347, DEC,
   June 1992

   [Deering92] Deering, S., "City Codes:  An Alternative Scheme for OSI
   NSAP Allocation in the Internet", Email message to Big-Internet
   mailing list, January 7, 1992.

   [Callon92b] CNAT

-Related Documents:

   [Hinden92b] Hinden, R., and D. Crocker, "A Proposal for IP Address
   Encapsulation (IPAE): A Compatible version of IP with Large
   Addresses", Work in Progress, June 1992.

   [Deering92b] Deering, S., "The Simple Internet Protocol", Big-
   Internet mailing list.

   [Stockman92] Karrenberg, D., and B. Stockman, "A Proposal for a
   Global Internet Addressing Scheme", Work in Progress, May 1992.




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   [Rekhter92] Rekhter, Y., and T. Li, "Guidelines for IP Address
   Allocation", Work in Progress, May 1992.

   [Rekhter92b] Rekhter, Y., and T. Li, "The Border Gateway Protocol
   (Version 4)", Work in Progress, September 1992.

   [Rekhter92c] Rekhter, Y., and P. Gross, "Application of the Border
   Gateway Protocol", Work in Progress, September 1992.

   [Gerich92]  Gerich, E., "Guidelines for Management of IP Address
   Space", RFC 1366, Merit, October 1992.

   [Solen92]  Solensky, F., and F. Kastenholz, "A Revision to IP Address
   Classifications", Work in Progress, March 1992.

   [Wang92]  Wany, Z.,  and J. Crowcroft, "A Two-Tier Address Structure
   for the Internet:  A Solution to the Problem of Address Space
   Exhaustion", RFC 1335,  University College London, May 1992.

   [Callon91]  Callon, R., Gardner, E., and R. Colella, "Guidelines for
   OSI NSAP Allocation in the Internet", RFC 1237, NIST, Mitre, DEC,
   July 1991.

   [Tsuchiya92a]  Tsuchiya, P., "The IP Network Address Translator
   (NAT): Preliminary Design", Work in Progress, April 1991.

   [Tsuchiya92b]  Tsuchiya, P., "The 'P' Internet Protocol", Work in
   Progress, May 1992.

   [Chiappa91]  Chiappa, J., "A New IP Routing and Addressing
   Architecture", Work in Progress, July 1991.

   [Clark91]  Clark, D., Chapin, L., Cerf, V., Braden, R., and R. Hobby,
   "Towards the Future Internet Architecture", RFC 1287, MIT, BBN, CNRI,
   ISI, UCDavis, December 1991.

Security Considerations

   Security issues are discussed in sections 4.4, B.2, B.10, and B.11.












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Authors' Addresses

   Phillip Gross, IESG Chair
   Advanced Network & Services
   100 Clearbrook Road
   Elmsford, NY

   Phone: 914-789-5300
   EMail: pgross@ans.net


   Philip Almquist
   Stanford University
   Networking Systems
   Pine Hall 147
   Stanford, CA 94305

   Phone: (415) 723-2229
   EMail: Almquist@JESSICA.STANFORD.EDU
































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