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

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.

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

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

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.

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.

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"

(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

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).

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.

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

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].

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

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.

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

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.

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.

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.

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

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", RFC1347, 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.

[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", RFC1366, 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", RFC1335, University College London, May 1992.

[Callon91] Callon, R., Gardner, E., and R. Colella, "Guidelines for
OSI NSAP Allocation in the Internet", RFC1237, 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", RFC1287, MIT, BBN, CNRI,
ISI, UCDavis, December 1991.

Security Considerations

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

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