INTERNET-DRAFT                                             Phill Gross
     September 1992                                              IESG Chair
                                                            Philip Almquist
                                                           IESG Internet AD
                  IESG Deliberations on Routing and Addressing
     Status Of This Memo
     2.1  The Problems
     2.2  Possible Solutions
     3.1 The IAB Architecture Retreats
     3.2 The Santa Fe IETF
     3.3 The ROAD Group and beyond
     4.1 The Need For Interim Solutions
     4.2 The Proposed Phases
     4.3 A Solution For Routing Table Explosion -- CIDR
     4.4 Regarding "IP Address Exhaustion"
     4.5 Milestones And Timetable For Making a Recommendation for
          "Bigger Internet Addresses"
     5. SUMMARY
     Appendix C. BIBLIOGRAPHY
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     This memo summarizes issues surrounding the routing and addressing
     scalling problems in the IP architecture, and it provides a brief
     background of the ROAD group and related activities in the IETF.
     It also provides a preliminary report of IESG deliberations on how
     these routing and addressing issues should be pursued in the IAB/IETF,
     Status Of This Memo
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     Distribution of this memo is unlimited.
     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 bibligraphies distributed on the Big-Internet
     mailing list.
     It seems unlikely that the designers of IP ever imagined at the time
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     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.
     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 recomendation from the IESG/IETF
     to the IAB.
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     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 exascerbate 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 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
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     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.
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     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
     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.
     3)   Use the class C address space to form aggregations of different
     size than the normal normal class C addesses.  Such schemes include
     Classless Inter-Domain Routing (CIDR) [Fuller92] and the C# scheme
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     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.
     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 signifcant
     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
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     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
     2)   Better tools.  Network operators and router vendors could
     work to develop more powerful paradigms and mechanisms for routing
      The IETF has already undertaken some work in the areas of route
     filtering  and route leaking.
     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
     gateways at the borders between routing domains.
     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.
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     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" (rather than  "subnetting").  This appraoch would
     eventually evolve into CIDR.  The  BGP WG decided to form a
     separate subgroup, to be led by Phill Gross  (ANS) to pursue this
     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 10^^9 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
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     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
     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.
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     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).
     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
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     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 assignement
          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 toplogy 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
     Without these advanced features, the Internet may fill an important
     niche, but will eventually be supplanted by other advanced
     technologies like ATM or SMDS.
     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
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     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 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
     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 (eg, C#, see Solen92) not did
     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 [Rekhter92] has now emerged.  [Rekhter92]
     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
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     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].
     d. Form a new WG to consider CIDR-related extensions to IDRP (eg,
     specify how run IDRP for IP inter-domain routing)
     e. Give careful consideration to how CIDR will be deployed in the
     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
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     - effect of supporting new protocols, such as for address
     - effect on network management and security, and
     - the costs to network operators and network users who must
        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
     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
     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].
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     Eventually, the call for proposals was made at the July meeting
     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
      August-November 1992 --  Proposed WGs submit charters, create
     discussion  lists, and begin their deliberations by email and/or face-
     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
      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.
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     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
     a bigger  Internet address space according to the timetable in section
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     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
      - 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
          SIP: (to be formed)
     - Attend the November IETF in Washington DC (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
     Internet Draft            Expires 5/1/93           October 1, 1992
     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.
     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
     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
     The changes should also include if hosts and routers have their
     current IP addresses changed.
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     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.
     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
     B.4  Large Internet Support
     The proposal should describe how it will scale to support a large
     internet of 10^^9 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
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     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
     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.
     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.
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     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
     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
     emerging internet problems such as security/authentication, mobility,
     resource allocation, accounting, high packet rates, etc.
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     Appendix C.  BIBLIOGRAPHY
     -Documents and Information from IETF/IESG:
     [Ford92] Ford, P., Gross, P., "Routing And Addressing
     Considerations", Proceedings of the Twenty-Third IETF, March
     [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., Varadhan, K.,
     "Supernetting:  an Address Assignment and Aggregation Strategy",
     RFC 1338, USC/Information Sciences Institute, 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,
     USC/Information Sciences Institute, 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., Crocker, D., "A Proposal for IP Address
     Encapsulation (IPAE): A Compatible version of IP with Large
     Addresses",Internet-Draft, June 1992.
     [Deering92b] Deering, S., "The Simple Internet Protocol",
     big-internet mailing list.
     [Stockman92] Karrenberg, D., Stockman, B., "A Proposal for a
     Global Internet Addressing Scheme", Internet-Draft, May 1992).
     [Rekhter92] Rekhter, Y., Li, T., "Guidelines for IP Address
     Allocation", Internet-Draft, May 1992.
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     [Rekhter92b] Rekhter, Y., Li, T., "The Border Gateway Protocol
     (Version 4)", Internet-Draft, September 1992.
     [Rekhter92c] Rekhter, Y., Gross, P.,  "Application of the Border
     Gateway Protocol", Internet-Draft, September 1992.
     [Solen92]  Solensky, F., Kastenholz, F., "A Revision to IP Address
     Classifications", Internet-Draft, March 1992.
     [Wang92]  Wany, Z.,  Crocroft, J., "A Two-Tier Address Structure
     for the Internet:  A Solution to the Problem of Address Space
     Exhaustion", RFC 1335,  USC/Information Sciences Institute, May
     [Callon91]  Callon, R., Gardner, E., Colella, R., "Guidelines for
     OSI NSAP Allocation in the Internet", RFC 1237, USC/Information
     Sciences Institute, July 1991.
     [Tsuchiya92a]  Tsuchiya, P., The IP Network Address Translator
     (NAT): Preliminary Design, deleted Internet-Draft, April 1991.
     [Tsuchiya92b]  Tsuchiya, P., "The 'P' Internet Protocol",
     Internet-Draft, May 1992.
     [Chiappa91]  Chiappa, J., "A New IP Routing and Addressing
     Architectue", deleted Internet-Draft, July 1991.
     [Clark91]  Clark, D., "Towards the Future Internet Architecture",
     RFC 1287, USC/Information Sciences Institute, December 19 91.