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IETF RFC 1752
The Recommendation for the IP Next Generation Protocol
Last modified on Friday, January 13th, 1995
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Network Working Group S. Bradner
Request for Comments: 1752 Harvard University
Category: Standards Track A. Mankin
ISI
January 1995
The Recommendation for the IP Next Generation Protocol
 Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This document presents the recommendation of the IPng Area Directors
on what should be used to replace the current version of the Internet
Protocol. This recommendation was accepted by the Internet
Engineering Steering Group (IESG).
Table of Contents
1. Summary. . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Background . . . . . . . . . . . . . . . . . . . . . . . 4
3. A Direction for IPng . . . . . . . . . . . . . . . . . . 5
4. IPng Area. . . . . . . . . . . . . . . . . . . . . . . . 6
5. ALE Working Group. . . . . . . . . . . . . . . . . . . . 6
5.1 ALE Projections. . . . . . . . . . . . . . . . . . . . . 7
5.2 Routing Table Size . . . . . . . . . . . . . . . . . . . 7
5.3 Address Assignment Policy Recommendations. . . . . . . . 8
6. IPng Technical Requirements. . . . . . . . . . . . . . . 8
6.1 The IPng Technical Criteria document . . . . . . . . . . 9
7. IPng Proposals . . . . . . . . . . . . . . . . . . . . . 11
7.1 CATNIP. . . . . . . . . . . . . . . . . . . . . . . . . 11
7.2 SIPP. . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3 TUBA. . . . . . . . . . . . . . . . . . . . . . . . . . 13
8. IPng Proposal Reviews. . . . . . . . . . . . . . . . . . 13
8.1 CATNIP Reviews . . . . . . . . . . . . . . . . . . . . . 14
8.2 SIPP Reviews . . . . . . . . . . . . . . . . . . . . . . 15
8.3 TUBA Reviews . . . . . . . . . . . . . . . . . . . . . . 16
8.4 Summary of Proposal Reviews. . . . . . . . . . . . . . . 17
9. A Revised Proposal . . . . . . . . . . . . . . . . . . . 17
10 Assumptions . . . . . . . . . . . . . . . . . . . . . . 18
10.1 Criteria Document and Timing of Recommendation . . . . . 18
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RFC 1752 Recommendation for IPng January 1995
10.2 Address Length . . . . . . . . . . . . . . . . . . . . . 19
11. IPng Recommendation. . . . . . . . . . . . . . . . . . . 19
11.1 IPng Criteria Document and IPng. . . . . . . . . . . . . 20
11.2 IPv6. . . . . . . . . . . . . . . . . . . . . . . . . . 21
12. IPv6 Overview . . . . . . . . . . . . . . . . . . . . . 21
12.1 IPv6 Header Format . . . . . . . . . . . . . . . . . . . 24
12.2 Extension Headers. . . . . . . . . . . . . . . . . . . . 25
12.2.1 Hop-by-Hop Option Header . . . . . . . . . . . . . . . . 25
12.2.2 IPv6 Header Options. . . . . . . . . . . . . . . . . . . 26
12.2.3 Routing Header . . . . . . . . . . . . . . . . . . . . . 27
12.2.4 Fragment Header. . . . . . . . . . . . . . . . . . . . . 28
12.2.5 Authentication Header. . . . . . . . . . . . . . . . . . 29
12.2.6 Privacy Header . . . . . . . . . . . . . . . . . . . . . 30
12.2.7 End-to-End Option Header . . . . . . . . . . . . . . . . 32
13. IPng Working Group . . . . . . . . . . . . . . . . . . . 32
14. IPng Reviewer . . . . . . . . . . . . . . . . . . . . . 33
15. Address Autoconfiguration. . . . . . . . . . . . . . . . 33
16. Transition . . . . . . . . . . . . . . . . . . . . . . . 34
16.1 Transition - Short Term. . . . . . . . . . . . . . . . . 35
16.2 Transition - Long Term . . . . . . . . . . . . . . . . . 36
17. Other Address Families . . . . . . . . . . . . . . . . . 37
18. Impact on Other IETF Standards . . . . . . . . . . . . . 38
19. Impact on non-IETF standards and on products . . . . . . 39
20. APIs . . . . . . . . . . . . . . . . . . . . . . . . . . 39
21. Future of the IPng Area and Working Groups . . . . . . . 40
22. Security Considerations. . . . . . . . . . . . . . . . . 40
23. Authors' Addresses . . . . . . . . . . . . . . . . . . . 43
Appendix A Summary of Recommendations . . . . . . . . . . . . . 44
Appendix B IPng Area Directorate. . . . . . . . . . . . . . . . 45
Appendix C Documents Referred to the IPng Working Groups. . . . 46
Appendix D IPng Proposal Overviews. . . . . . . . . . . . . . . 46
Appendix E RFC 1550 White Papers. . . . . . . . . . . . . . . . 47
Appendix F Additional References. . . . . . . . . . . . . . . . 48
Appendix G Acknowledgments. . . . . . . . . . . . . . . . . . . 52
1. Summary
The IETF started its effort to select a successor to IPv4 in late
1990 when projections indicated that the Internet address space would
become an increasingly limiting resource. Several parallel efforts
then started exploring ways to resolve these address limitations
while at the same time providing additional functionality. The IETF
formed the IPng Area in late 1993 to investigate the various
proposals and recommend how to proceed. We developed an IPng
technical criteria document and evaluated the various proposals
against it. All were found wanting to some degree. After this
evaluation, a revised proposal was offered by one of the working
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RFC 1752 Recommendation for IPng January 1995
groups that resolved many of the problems in the previous proposals.
The IPng Area Directors recommend that the IETF designate this
revised proposal as the IPng and focus its energy on bringing a set
of documents defining the IPng to Proposed Standard status with all
deliberate speed.
This protocol recommendation includes a simplified header with a
hierarchical address structure that permits rigorous route
aggregation and is also large enough to meet the needs of the
Internet for the foreseeable future. The protocol also includes
packet-level authentication and encryption along with plug and play
autoconfiguration. The design changes the way IP header options are
encoded to increase the flexibility of introducing new options in the
future while improving performance. It also includes the ability to
label traffic flows.
Specific recommendations include:
* current address assignment policies are adequate
* there is no current need to reclaim underutilized assigned network
numbers
* there is no current need to renumber major portions of the Internet
* CIDR-style assignments of parts of unassigned Class A address space
should be considered
* "Simple Internet Protocol Plus (SIPP) Spec. (128 bit ver)"
[Deering94b] be adopted as the basis for IPng
* the documents listed in Appendix C be the foundation of the IPng
effort
* an IPng Working Group be formed, chaired by Steve Deering and Ross
Callon
* Robert Hinden be the document editor for the IPng effort
* an IPng Reviewer be appointed and that Dave Clark be the reviewer
* an Address Autoconfiguration Working Group be formed, chaired by
Dave Katz and Sue Thomson
* an IPng Transition Working Group be formed, chaired by Bob Gilligan
and TBA
* the Transition and Coexistence Including Testing Working Group be
chartered
* recommendations about the use of non-IPv6 addresses in IPv6
environments and IPv6 addresses in non-IPv6 environments be
developed
* the IESG commission a review of all IETF standards documents for
IPng implications
* the IESG task current IETF working groups to take IPng into account
* the IESG charter new working groups where needed to revise old
standards documents
* Informational RFCs be solicited or developed describing a few
specific IPng APIs
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RFC 1752 Recommendation for IPng January 1995
* the IPng Area and Area Directorate continue until main documents
are offered as Proposed Standards in late 1994
* support for the Authentication Header be required
* support for a specific authentication algorithm be required
* support for the Privacy Header be required
* support for a specific privacy algorithm be required
* an "IPng framework for firewalls" be developed
2. Background
Even the most farseeing of the developers of TCP/IP in the early
1980s did not imagine the dilemma of scale that the Internet faces
today. 1987 estimates projected a need to address as many as 100,000
networks at some vague point in the future. [Callon87] We will reach
that mark by 1996. There are many realistic projections of many
millions of interconnected networks in the not too distant future.
[Vecchi94, Taylor94]
Further, even though the current 32 bit IPv4 address structure can
enumerate over 4 billion hosts on as many as 16.7 million networks,
the actual address assignment efficiency is far less than that, even
on a theoretical basis. [Huitema94] This inefficiency is exacerbated
by the granularity of assignments using Class A, B and C addresses.
In August 1990 during the Vancouver IETF meeting, Frank Solensky,
Phill Gross and Sue Hares projected that the current rate of
assignment would exhaust the Class B space by March of 1994.
The then obvious remedy of assigning multiple Class C addresses in
place of Class B addresses introduced its own problem by further
expanding the size of the routing tables in the backbone routers
already growing at an alarming rate.
We faced the dilemma of choosing between accepting either limiting
the rate of growth and ultimate size of the Internet, or disrupting
the network by changing to new techniques or technologies.
The IETF formed the Routing and Addressing (ROAD) group in November
1991 at the Santa Fe IETF meeting to explore this dilemma and guide
the IETF on the issues. The ROAD group reported their work in March
1992 at the San Diego IETF meeting. [Gross92] The impact of the
recommendations ranged from "immediate" to "long term" and included
adopting the CIDR route aggregation proposal [Fuller93] for reducing
the rate of routing table growth and recommending a call for
proposals "to form working groups to explore separate approaches for
bigger Internet addresses."
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RFC 1752 Recommendation for IPng January 1995
In the late spring of 1992 the IAB issued "IP version 7" [IAB92],
concurring in the ROAD group's endorsement of CIDR and also
recommending "an immediate IETF effort to prepare a detailed and
organizational plan for using CLNP as the basis for IPv7." After
spirited discussion, the IETF decided to reject the IAB's
recommendation and issue the call for proposals recommended by the
ROAD group. This call was issued in July 1992 at the Boston IETF
meeting and a number of working groups were formed in response
During the July 1993 Amsterdam IETF meeting an IPng (IP Next
Generation) Decision Process (ipdecide) BOF was held. This BOF "was
intended to help re-focus attention on the very important topic of
making a decision between the candidates for IPng. The BOF focused on
the issues of who should take the lead in making the recommendation
to the community and what criteria should be used to reach the
recommendation." [Carpen93]
3. A Direction for IPng
In September 1993 Phill Gross, chair of the IESG issued "A Direction
for IPng". [Gross94] In this memo he summarized the results of the
ipdecide BOF and open IESG plenary in Amsterdam.
* The IETF needs to move toward closure on IPng.
* The IESG has the responsibility for developing an IPng
recommendation for the Internet community.
* The procedures of the recommendation-making process should be open
and published well in advance by the IESG.
* As part of this process, the IPng WGs may be given new milestones
and other guidance to aid the IESG.
* There should be ample opportunity for community comment prior to
final IESG recommendation.
The memo also announced "a temporary, ad hoc, 'area' to deal
specifically with IPng issues." Phill asked two of the current IESG
members, Allison Mankin (Transport Services Area) and Scott Bradner
(Operational Requirements Area), to act as Directors for the new
area. The Area Directors were given a specific charge on how to
investigate the various IPng proposals and how to base their
recommendation to the IETF. It was also requested that a specific
recommendation be made.
* Establish an IPng directorate.
* Ensure that a completely open process is followed.
* Develop an understanding of the level of urgency and the time
constraints imposed by the rate of address assignment and rate of
growth in the routing tables.
* Recommend the adoption of assignment policy changes if warranted.
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RFC 1752 Recommendation for IPng January 1995
* Define the scope of the IPng effort based on the understanding of
the time constraints.
* Develop a clear and concise set of technical requirements and
decision criteria for IPng.
* Develop a recommendation about which of the current IPng candidates
to accept, if any.
4. IPng Area
After the IPng Area was formed, we recruited a directorate. (Appendix
B) The members of the directorate were chosen both for their general
and specific technical expertise. The individuals were then asked to
have their management authorize this participation in the process and
confirm that they understood the IETF process.
We took great care to ensure the inclusion of a wide spectrum of
knowledge. The directors are experts in security, routing, the needs
of large users, end system manufacturers, Unix and non-Unix
platforms, router manufacturers, theoretical researchers, protocol
architecture, and the operating regional, national, and international
networks. Additionally, several members of the directorate were
deeply involved in each of the IPng proposal working groups.
The directorate functions as a direction-setting and preliminary
review body as requested by the charge to the area. The directorate
engages in biweekly conference calls, participates in an internal
mailing list and corresponds actively on the Big-Internet mailing
list. The directorate held open meetings during the March 1994
Seattle and July 1994 Toronto IETF meetings as well as two additional
multi-day retreats. To ensure that the IPng process was as open as
possible, we took minutes during these meetings and then published
them. Additionally, we placed the archives of the internal IPng
mailing list on an anonymous ftp site. (Hsdndev.harvard.edu:
pub/ipng.)
5. ALE Working Group
We needed a reasonable estimate of the time remaining before we
exhausted the IPv4 address space in order to determine the scope of
the IPng effort. If the time remaining was about the same needed to
deploy a replacement, then we would have select the IPng which would
only fix the address limitations since we would not have enough time
to develop any other features. If more time seemed available, we
could consider additional improvements.
The IETF formed an Address Lifetime Expectations (ALE) Working Group
in 1993 "to develop an estimate for the remaining lifetime of the
IPv4 address space based on currently known and available
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RFC 1752 Recommendation for IPng January 1995
technologies." [Solens93a] Tony Li of Cisco Systems and Frank
Solensky of FTP Software are the co-chairs. The IETF also charged
the working group to consider if developing more stringent address
allocation and utilization policies might provide more time for the
transition.
5.1 ALE Projections
The ALE Working Group met during the November 1993 Houston,
[Solens93b] March 1994 Seattle [Bos93] and July 1994 Toronto
[Solens94] IETF meetings. They projected at the Seattle meeting,
later confirmed at the Toronto meeting that, using the current
allocation statistics, the Internet would exhaust the IPv4 address
space between 2005 and 2011.
Some members of the ipv4-ale and big-internet mailing lists called
into question the reliability of this projection. It has been
criticized as both too optimistic and as too pessimistic.
Some people pointed out that this type of projection makes an
assumption of no paradigm shifts in IP usage. If someone were to
develop a new 'killer application', (for example cable-TV set top
boxes.) The resultant rise in the demand for IP addresses could make
this an over-estimate of the time available.
There may also be a problem with the data used to make the
projection. The InterNIC allocates IP addresses in large chunks to
regional Network Information Centers (NICs) and network providers.
The NICs and the providers then re-allocate addresses to their
customers. The ALE projections used the InterNIC assignments without
regard to the actual rate of assignment of addresses to the end
users. They did the projection this way since the accuracy of the
data seems quite a bit higher. While using this once-removed data
may add a level of over-estimation since it assumes the rate of large
block allocation will continue, this may not be the case.
These factors reduce the reliability of the ALE estimates but, in
general, they seem to indicate enough time remaining in the IPv4
address space to consider adding features in an IPng besides just
expanding the address size even when considering time required for
development, testing, and deployment.
5.2 Routing Table Size
Another issue in Internet scaling is the increasing size of the
routing tables required in the backbone routers. Adopting the CIDR
block address assignment and aggregating routes reduced the size of
the tables for awhile but they are now expanding again. Providers now
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RFC 1752 Recommendation for IPng January 1995
need to more aggressively advertise their routes only in aggregates.
Providers must also advise their new customers to renumber their
networks in the best interest of the entire Internet community.
The problem of exhausting the IPv4 address space may be moot if this
issue is ignored and if routers cannot be found that can keep up with
the table size growth. Before implementing CIDR the backbone routing
table was growing at a rate about 1.5 times as fast as memory
technology.
We should also note that even though IPng addresses are designed with
aggregation in mind switching to IPng will not solve the routing
table size problem unless the addresses are assigned rigorously to
maximize the affect of such aggregation. This efficient advertising
of routes can be maintained since IPng includes address
autoconfiguration mechanisms to allow easy renumbering if a customer
decides to switch providers. Customers who receive service from more
than one provider may limit the ultimate efficiency of any route
aggregation. [Rekhter94]
5.3 Address Assignment Policy Recommendations
The IESG Chair charged the IPng Area to consider recommending more
stringent assignment policies, reclaiming some addresses already
assigned, or making a serious effort to renumber significant portions
of the Internet. [Gross94]
The IPng Area Directors endorse the current address assignment
policies in view of the ALE projections. We do not feel that anyone
should take specific efforts to reclaim underutilized addresses
already assigned or to renumber forcefully major portions of the
Internet. We do however feel that we should all encourage network
service providers to assist new customers in renumbering their
networks to conform to the provider's CIDR assignments.
The ALE Working Group recommends that we consider assigning CIDR-type
address blocks out of the unassigned Class A address space. The IPng
Area Directors concur with this recommendation.
6. IPng Technical Requirements
The IESG provided an outline in RFC 1380 [Gross92] of the type of
criteria we should use to determine the suitability of an IPng
proposal. The IETF further refined this understanding of the
appropriate criteria with the recommendations of a Selection Criteria
BOF held during the November 1992 IETF meeting in Washington D.C.
[Almqu92] We felt we needed to get additional input for determining
the requirements and issued a call for white papers. [Bradner93] This
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RFC 1752 Recommendation for IPng January 1995
call, issued as RFC 1550, intended to reach both inside and outside
the traditional IETF constituency to get the broadest possible
understanding of the requirements for a data networking protocol with
the broadest possible application.
We received twenty one white papers in response to the RFC 1550
solicitation. ( Appendix E) We received responses from the
industries that many feel will be the major providers of data
networking services in the future; the cable TV industry [Vecchi94],
the cellular industry [Taylor94], and the electric power industry
[Skelton94]. In addition, we received papers that dealt with
military applications [Adam94, Syming94, Green94], ATM [Brazd94],
mobility [Simpson94], accounting [Brown94], routing [Estrin94a,
Chiappa94], security [Adam94, Bell94b, Brit94, Green94, Vecchi94,
Flei94], large corporate networking [Britt94, Fleisch94], transition
[Carpen94a, Heager94], market acceptance [Curran94, Britt94], host
implementations [Bound94], as well as a number of other issues.
[Bello94a, Clark94, Ghisel94]
These white papers, a Next Generation Requirements (ngreq) BOF
(chaired by Jon Crowcroft and Frank Kastenholz) held during the March
1994 Seattle IETF meeting, discussions within the IPng Area
Directorate and considerable discussion on the big-internet mailing
list were all used by Frank Kastenholz and Craig Partridge in
revising their earlier criteria draft [Kasten92] to produce
"Technical Criteria for Choosing IP The Next Generation (IPng)."
[Kasten94] This document is the "clear and concise set of technical
requirements and decision criteria for IPng" called for in the charge
from the IESG Chair. We used this document as the basic guideline
while evaluating the IPng proposals.
6.1 The IPng Technical Criteria document
The criteria described in this document include: (from Kasten94)
* complete specification - The proposal must completely describe the
proposed protocol. We must select an IPng by referencing specific
documents, not to future work.
* architectural simplicity - The IP-layer protocol should be as
simple as possible with functions located elsewhere that are more
appropriately performed at protocol layers other than the IP layer.
* scale - The IPng Protocol must allow identifying and addressing at
least 10**9 leaf-networks (and preferably much more)
* topological flexibility - The routing architecture and protocols
ofIPng must allow for many different network topologies. They must
not assume that the network's physical structure is a tree.
* performance - A state of the art, commercial grade router must be
able to process and forward IPng traffic at speeds capable of fully
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RFC 1752 Recommendation for IPng January 1995
utilizing common, commercially available, high-speed media at the
time.
* robust service - The network service and its associated routing and
control protocols must be robust.
* transition - The protocol must have a straightforward transition
plan from IPv4.
* media independence - The protocol must work across an internetwork
of many different LAN, MAN, and WAN media, with individual link
speeds ranging from a ones-of-bits per second to hundreds of
gigabits per second.
* datagram service - The protocol must support an unreliable datagram
delivery service.
* configuration ease - The protocol must permit easy and largely
distributed configuration and operation. Automatic configuration of
hosts and routers is required.
* security - IPng must provide a secure network layer.
* unique names - IPng must assign unique names to all IP-Layer
objects in the global, ubiquitous, Internet. These names may or
may not have any location, topology, or routing significance.
* access to standards - The protocols that define IPng and its
associated protocols should be as freely available and
redistributable as the IPv4 and related RFCs. There must be no
specification-related licensing fees for implementing or selling
IPng software.
* multicast support - The protocol must support both unicast and
multicast packet transmission. Dynamic and automatic routing of
multicasts is also required.
* extensibility - The protocol must be extensible; it must be able
to evolve to meet the future service needs of the Internet. This
evolution must be achievable without requiring network-wide
software upgrades.
* service classes - The protocol must allow network devices to
associate packets with particular service classes and provide them
with the services specified by those classes.
* mobility - The protocol must support mobile hosts, networks and
internetworks.
* control protocol - The protocol must include elementary support for
testing and debugging networks. (e.g., ping and traceroute)
* tunneling support - IPng must allow users to build private
internetworks on top of the basic Internet Infrastructure. Both
private IP-based internetworks and private non-IP-based (e.g., CLNP
or AppleTalk) internetworks must be supported.
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RFC 1752 Recommendation for IPng January 1995
7. IPng Proposals
By the time that the IPng Area was formed, the IETF had already aimed
a considerable amount of IETF effort at solving the addressing and
routing problems of the Internet. Several proposals had been made
and some of these reached the level of having a working group
chartered. A number of these groups subsequently merged forming
groups with a larger consensus. These efforts represented different
views on the issues which confront us and sought to optimize
different aspects of the possible solutions.
By February 1992 the Internet community developed four separate
proposals for IPng [Gross92], "CNAT" [Callon92a], "IP Encaps"
[Hinden92a], "Nimrod" [Chiappa91], and "Simple CLNP" [Callon92b]. By
December 1992 three more proposals followed; "The P Internet
Protocol" (PIP) [Tsuchiya92], "The Simple Internet Protocol" (SIP)
[Deering92] and "TP/IX" [Ullmann93]. After the March 1992 San Diego
IETF meeting "Simple CLNP" evolved into "TCP and UDP with Bigger
Addresses" (TUBA) [Callon92c] and "IP Encaps" evolved into "IP
Address Encapsulation" (IPAE) [Hinden92b].
By November 1993, IPAE merged with SIP while still maintaining the
name SIP. This group then merged with PIP and the resulting working
group called themselves "Simple Internet Protocol Plus" (SIPP). At
the same time the TP/IX Working Group changed its name to "Common
Architecture for the Internet" (CATNIP).
None of these proposals were wrong nor were others right. All of the
proposals would work in some ways providing a path to overcome the
obstacles we face as the Internet expands. The task of the IPng Area
was to ensure that the IETF understand the offered proposals, learn
from the proposals and provide a recommendation on what path best
resolves the basic issues while providing the best foundation upon
which to build for the future.
The IPng Area evaluated three IPng proposals as they were described
in their RFC 1550 white papers: CATNIP [McGovern94] , SIPP
[Hinden94a] and TUBA. [Ford94a]. The IESG viewed Nimrod as too much
of a research project for consideration as an IPng candidate. Since
Nimrod represents one possible future Internet routing strategy we
solicited a paper describing any requirements Nimrod would put on an
IPng to add to the requirements process. [Chiappa94]
7.1 CATNIP
"Common Architecture for the Internet (CATNIP) was conceived as a
convergence protocol. CATNIP integrates CLNP, IP, and IPX. The CATNIP
design provides for any of the transport layer protocols in use, for
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RFC 1752 Recommendation for IPng January 1995
example TP4, CLTP, TCP, UDP, IPX and SPX, to run over any of the
network layer protocol formats: CLNP, IP (version 4), IPX, and
CATNIP. With some attention paid to details, it is possible for a
transport layer protocol (such as TCP) to operate properly with one
end system using one network layer (e.g., IP version 4) and the other
using some other network protocol, such as CLNP." [McGovern94]
"The objective is to provide common ground between the Internet, OSI,
and the Novell protocols, as well as to advance the Internet
technology to the scale and performance of the next generation of
internetwork technology."
"CATNIP supports OSI Network Service Access Point (NSAP) format
addresses. It also uses cache handles to provide both rapid
identification of the next hop in high performance routing as well as
abbreviation of the network header by permitting the addresses to be
omitted when a valid cache handle is available. The fixed part of the
network layer header carries the cache handles." [Sukonnik94]
7.2 SIPP
"Simple Internet Protocol Plus (SIPP) is a new version of IP which is
designed to be an evolutionary step from IPv4. It is a natural
increment to IPv4. It was not a design goal to take a radical step
away from IPv4. Functions which work in IPv4 were kept in SIPP.
Functions which didn't work were removed. It can be installed as a
normal software upgrade in internet devices and is interoperable with
the current IPv4. Its deployment strategy was designed to not have
any 'flag' days. SIPP is designed to run well on high performance
networks (e.g., ATM) and at the same time is still efficient for low
bandwidth networks (e.g., wireless). In addition, it provides a
platform for new internet functionality that will be required in the
near future." [Hinden94b]
"SIPP increases the IP address size from 32 bits to 64 bits, to
support more levels of addressing hierarchy and a much greater number
of addressable nodes. SIPP addressing can be further extended, in
units of 64 bits, by a facility equivalent to IPv4's Loose Source and
Record Route option, in combination with a new address type called
'cluster addresses' which identify topological regions rather than
individual nodes."
"SIPP changes in the way IP header options are encoded allows for
more efficient forwarding, less stringent limits on the length of
options, and greater flexibility for introducing new options in the
future. A new capability is added to enable the labeling of packets
belonging to particular traffic 'flows' for which the sender requests
special handling, such as non-default quality of service or 'real-
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RFC 1752 Recommendation for IPng January 1995
time' service." [Hinden94a]
7.3 TUBA
"The TCP/UDP Over CLNP-Addressed Networks (TUBA) proposal seeks to
minimize the risk associated with migration to a new IP address
space. In addition, this proposal is motivated by the requirement to
allow the Internet to scale, which implies use of Internet
applications in a very large ubiquitous worldwide Internet. It is
therefore proposed that existing Internet transport and application
protocols continue to operate unchanged, except for the replacement
of 32-bit IP addresses with larger addresses. TUBA does not mean
having to move over to OSI completely. It would mean only replacing
IP with CLNP. TCP, UDP, and the traditional TCP/IP applications would
run on top of CLNP." [Callon92c]
"The TUBA effort will expand the ability to route Internet packets by
using addresses which support more hierarchy than the current
Internet Protocol (IP) address space. TUBA specifies the continued
use of Internet transport protocols, in particular TCP and UDP, but
specifies their encapsulation in ISO 8473 (CLNP) packets. This will
allow the continued use of Internet application protocols such as
FTP, SMTP, TELNET, etc. TUBA seeks to upgrade the current system by
a transition from the use of IPv4 to ISO/IEC 8473 (CLNP) and the
corresponding large Network Service Access Point (NSAP) address
space." [Knopper94]
"The TUBA proposal makes use of a simple long-term migration proposal
based on a gradual update of Internet Hosts (to run Internet
applications over CLNP) and DNS servers (to return larger addresses).
This proposal requires routers to be updated to support forwarding of
CLNP (in addition to IP). However, this proposal does not require
encapsulation nor translation of packets nor address mapping. IP
addresses and NSAP addresses may be assigned and used independently
during the migration period. Routing and forwarding of IP and CLNP
packets may be done independently." ([Callon92c]
8. IPng Proposal Reviews
The IPng Directorate discussed and reviewed the candidate proposals
during its biweekly teleconferences and through its mailing list. In
addition, members of the Big-Internet mailing list discussed many of
the aspects of the proposals, particularly when the Area Directors
posted several specific questions to stimulate discussion. [Big]
The directorate members were requested to each evaluate the proposals
in preparation for a two day retreat held near Chicago on May 19th
and 20th 1994. The retreat opened with a roundtable airing of the
Bradner & Mankin PAGE 13
RFC 1752 Recommendation for IPng January 1995
views of each of the participants, including the Area Directors, the
Directorate and a number of guests invited by the working group
chairs for each for the proposals. [Knopper94b] We will publish
these reviews as well as a more detailed compendium review of each of
the proposals as companion memos.
The following table summarizes each of the three proposals reviewed
against the requirements in the IPng Criteria document. They do not
necessarily reflect the views of the Area Directors. "Yes" means the
reviewers mainly felt the proposal met the specific criterion. "No"
means the reviewers mainly felt the proposal did not meet the
criterion. "Mixed" means that the reviewers had mixed reviews with
none dominating. "Unknown" means that the reviewers mainly felt the
documentation did not address the criterion.
CATNIP SIPP TUBA
------ ---- ----
complete spec no yes mostly
simplicity no no no
scale yes yes yes
topological flex yes yes yes
performance mixed mixed mixed
robust service mixed mixed yes
transition mixed no mixed
media indepdnt yes yes yes
datagram yes yes yes
config. ease unknown mixed mixed
security unknown mixed mixed
unique names mixed mixed mixed
access to stds yes yes mixed
multicast unknown yes mixed
extensibility unknown mixed mixed
service classes unknown yes mixed
mobility unknown mixed mixed
control proto unknown yes mixed
tunneling unknown yes mixed
8.1 CATNIP Reviews
All the reviewers felt that CATNIP is not completely specified.
However, many of the ideas in CATNIP are innovative and a number of
reviewers felt CATNIP shows the best vision of all of the proposals.
The use of Network Service Attachment Point Addresses (NSAPs) is well
thought out and the routing handles are innovative.
While the goal of uniting three major protocol families, IP, ISO-CLNP
and Novell IPX is laudable our consensus was that the developers had
not developed detailed enough plans to support realizing that goal.
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RFC 1752 Recommendation for IPng January 1995
The plans they do describe suffer from the complexity of trying to be
the union of a number of existing network protocols. Some reviewers
felt that CATNIP is basically maps IPv4, IPX, and SIPP addresses into
NSAPs and, as such, does not deal with the routing problems of the
current and future Internet.
Additionally the reviewers felt that CATNIP has poor support for
multicasting and mobility and does not specifically deal with such
important topics as security and autoconfiguration.
8.2 SIPP Reviews
Most of the reviewers, including those predisposed to other
proposals, felt as one reviewer put it, that SIPP is an
"aesthetically beautiful protocol well tailored to compactly satisfy
today's known network requirements." The SIPP Working Group has been
the most dynamic over the last year, producing a myriad of
documentation detailing almost all of the aspects necessary to
produce a complete protocol description.
The biggest problem the reviewers had with SIPP was with IPAE, SIPP's
transition plan. The overwhelming feeling was that IPAE is fatally
flawed and could not be made to work reliably in an operational
Internet.
There was significant disagreement about the adequacy of the SIPP 64
bit address size. Although you can enumerate 10**15 end nodes in 64
bits people have different views about how much inefficiency real-
world routing plans introduce. [Huitema94] The majority felt that 64
bit addresses do not provide adequate space for the hierarchy
required to meet the needs of the future Internet. In addition since
no one has any experience with extended addressing and routing
concepts of the type proposed in SIPP, the reviewers generally felt
quite uncomfortable with this methodology. The reviewers also felt
that the design introduces some significant security issues.
A number of reviewers felt that SIPP did not address the routing
issue in any useful way. In particular, there has been no serious
attempt made at developing ways to abstract topology information or
to aggregate information about areas of the network.
Finally, most of the reviewers questioned the level of complexity in
the SIPP autoconfiguration plans as well as in SIPP in general, other
than the header itself.
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RFC 1752 Recommendation for IPng January 1995
8.3 TUBA Reviews
The reviewers generally felt that the most important thing that TUBA
has offers is that it is based on CLNP and there is significant
deployment of CLNP-capable routers throughout the Internet. There
was considerably less agreement that there was significant deployment
of CLNP-capable hosts or actual networks running CLNP. Another
strong positive for TUBA is the potential for convergence of ISO and
IETF networking standards. A number of reviewers pointed out that,
if TUBA were to be based on a changed CLNP then the advantage of an
existing deployed infrastructure would be lost and that the
convergence potential would be reduced.
A number of aspects of CLNP were felt to be a problem by the
reviewers including the inefficiencies introduced by the lack of any
particular word alignment of the header fields, CLNP source route,
the lack of a flow ID field, the lack of a protocol ID field, and the
use of CLNP error messages in TUBA. The CLNP packet format or
procedures would have to be modified to resolve at least some of
these issues.
There seems to be a profound disagreement within the TUBA community
over the question of the ability of the IETF to modify the CLNP
standards. In our presentation in Houston we said that we felt that
"clone and run" was a legitimate process. This is also what the IAB
proposed in "IP version 7". [IAB92] The TUBA community has not
reached consensus that this view is reasonable. While many,
including a number of the CLNP document authors, are adamant that
this is not an issue and the IETF can make modifications to the base
standards, many others are just as adamant that the standards can
only be changed through the ISO standards process. Since the
overwhelming feeling within the IETF is that the IETF must 'own' the
standards on which it is basing its future, this disagreement within
the TUBA community was disquieting.
For a number of reasons, unfortunately including prejudice in a few
cases, the reviews of the TUBA proposals were much more mixed than
for SIPP or CATNIP. Clearly TUBA meets the requirements for the
ability to scale to large numbers of hosts, supports flexible
topologies, is media independent and is a datagram protocol. To the
reviewers, it was less clear that TUBA met the other IPng
requirements and these views varied widely.
There was also disagreement over the advisability of using NSAPs for
routing given the wide variety of NSAP allocation plans. The
Internet would have to restrict the use of NSAPs to those which are
allocated with the actual underlying network topology in mind if the
required degree of aggregation of routing information is to be
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RFC 1752 Recommendation for IPng January 1995
achieved.
8.4 Summary of Proposal Reviews
To summarize, significant problems were seen in all three of the
proposals. The feeling was that, to one degree or another, both SIPP
and TUBA would work in the Internet context but each exhibited its
own problems. Some of these problems would have to be rectified
before either one would be ready to replace IPv4, much less be the
vehicle to carry the Internet into the future. Other problems could
be addressed over time. CATNIP was felt to be too incomplete to be
considered.
9. A Revised Proposal
As mentioned above, there was considerable discussion of the
strengths and weaknesses of the various IPng proposals during the
IPng 'BigTen' retreat on May 19th and 20th 1994. [Knopper94b] After
this retreat Steve Deering and Paul Francis, two of the co-chairs of
the SIPP Working Group, sent a message to the sipp mailing list
detailing the discussions at the retreat and proposing some changes
in SIPP. [Deering94a]
The message noted "The recurring (and unsurprising) concerns about
SIPP were:
(1) complexity/manageability/feasibility of IPAE, and
(2) adequacy/correctness/limitations of SIPP's addressing and routing
model, especially the use of loose source routing to accomplish
'extended addressing'".
They "proposed to address these concerns by changing SIPP as follows:
* Change address size from 8 bytes to 16 bytes (fixed-length).
* Specify optional use of serverless autoconfiguration of the 16-byte
address by using IEEE 802 address as the low-order ("node ID")
part.
* For higher-layer protocols that use internet-layer addresses as
part of connection identifiers (e.g., TCP), require that they use
the entire 16-byte addresses.
* Do *not* use Route Header for extended addressing."
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RFC 1752 Recommendation for IPng January 1995
After considerable discussion on the sipp and big-internet mailing
lists about these proposed changes, the SIPP working group published
a revised version of SIPP [Deering94b], a new addressing architecture
[Francis94], and a simplified transition mechanism [Gillig94a].
These were submitted to the IPng Directorate for their consideration.
This proposal represents a synthesis of multiple IETF efforts with
much of the basic protocol coming from the SIPP effort, the
autoconfiguration and transition portions influenced by TUBA, the
addressing structure is based on the CIDR work and the routing header
evolving out of the SDRP deliberations.
10. Assumptions
10.1 Criteria Document and Timing of Recommendation
In making the following recommendations we are making two assumptions
of community consensus; that the IPng criteria document represents
the reasonable set of requirements for an IPng, and that a specific
recommendation should be made now and that from this point on the
IETF should proceed with a single IPng effort.
As described above, the IPng Technical Criteria document [Kasten94]
was developed in a open manner and was the topic of extensive
discussions on a number of mailing lists. We believe that there is a
strong consensus that this document accurately reflects the
community's set of technical requirements which an IPng should be
able to meet.
A prime topic of discussion on the big-internet mailing list this
spring as well as during the open IPng directorate meeting in
Seattle, was the need to make a specific IPng recommendation at this
time. Some people felt that additional research would help resolve
some of the issues that are currently unresolved. While others
argued that selecting a single protocol to work on would clarify the
picture for the community, focus the resources of the IETF on
finalizing its details, and, since the argument that there were open
research items could be made at any point in history, there might
never be a 'right' time.
Our reading of the community is that there is a consensus that a
specific recommendation should be made now. This is consistent with
the views expressed during the ipdecide BOF in Amsterdam [Gross94]
and in some of the RFC 1550 white papers [Carpen94a].
There is no particular reason to think that the basic recommendation
would be significantly different if we waited for another six months
or a year. Clearly some details which are currently unresolved could
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RFC 1752 Recommendation for IPng January 1995
be filled in if the recommendation were to be delayed, but the
current fragmentation of the IETF's energies limits the efficiency of
this type of detail resolution. Concentrating the resources of the
IETF behind a single effort seems to us to be a more efficient way to
proceed.
10.2 Address Length
One of the most hotly discussed aspects of the IPng design
possibilities was address size and format. During the IPng process
four distinct views were expressed about these issues:
1. The view that 8 bytes of address are enough to meet the current
and future needs of the Internet (squaring the size of the IP
address space). More would waste bandwidth, promote inefficient
assignment, and cause problems in some networks (such as mobiles
and other low speed links).
2. The view that 16 bytes is about right. That length supports easy
auto-configuration as well as organizations with complex internal
routing topologies in conjunction with the global routing topology
now and well into the future.
3. The view that 20 byte OSI NSAPs should be used in the interests of
global harmonization.
4. The view that variable length addresses which might be smaller or
larger than 16 bytes should be used to embrace all the above
options and more, so that the size of the address could be
adjusted to the demands of the particular environment, and to
ensure the ability to meet any future networking requirements.
Good technical and engineering arguments were made for and against
all of these views. Unanimity was not achieved, but we feel that a
clear majority view emerged that the use of 16 byte fixed length
addresses was the best compromise between efficiency, functionality,
flexibility, and global applicability. [Mankin94]
11. IPng Recommendation
After a great deal of discussion in many forums and with the
consensus of the IPng Directorate, we recommend that the protocol
described in "Simple Internet Protocol Plus (SIPP) Spec. (128 bit
ver)" [Deering94b] be adopted as the basis for IPng, the next
generation of the Internet Protocol. We also recommend that the
other documents listed in Appendix C be adopted as the basis of
specific features of this protocol.
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RFC 1752 Recommendation for IPng January 1995
This proposal resolves most of the perceived problems, particularly
in the areas of addressing, routing, transition and address
autoconfiguration. It includes the broad base of the SIPP proposal
effort, flexible address autoconfiguration features, and a merged
transition strategy. We believe that it meets the requirements
outlined in the IPng Criteria document and provides the framework to
fully meet the needs of the greater Internet community for the
foreseeable future.
11.1 IPng Criteria Document and IPng
A detailed review of how IPng meets the requirements set down in the
IPng Criteria document [Kasten94] will soon be published. Following
is our feelings about the extent to which IPng is responsive to the
criteria.
* complete specification - the base specifications for IPng are
complete but transition and address autoconfiguration do remain to
be finalized
* architectural simplicity - the protocol is simple, easy to explain
and uses well established paradigms
* scale - an address size of 128 bits easily meets the need to
address 10**9 networks even in the face of the inherent
inefficiency of address allocation for efficient routing
* topological flexibility - the IPng design places no constraints on
network topology except for the limit of 255 hops
* performance - the simplicity of processing, the alignment of the
fields in the headers, and the elimination of the header checksum
will allow for high performance handling of IPng data streams
* robust service - IPng includes no inhibitors to robust service and
the addition of packet-level authentication allows the securing of
control and routing protocols without having to have separate
procedures
* transition - the IPng transition plan is simple and realistically
covers the transition methods that will be present in the
marketplace
* media independence - IPng retains IPv4's media independence, it may
be possible to make use of IPng's Flow Label in some connection-
oriented media such as ATM
* datagram service - IPng preserves datagram service as its basic
operational mode, it is possible that the use of path MTU discovery
will complicate the use of datagrams in some cases
* configuration ease - IPng will have easy and flexible address
autoconfiguration which will support a wide variety of environments
from nodes on an isolated network to nodes deep in a complex
internet
* security - IPng includes specific mechanisms for authentication and
encryption at the internetwork layer; the security features do rely
Bradner & Mankin PAGE 20
RFC 1752 Recommendation for IPng January 1995
on the presence of a yet to be defined key management system
* unique names - IPng addresses may be used as globally unique names
although they do have topological significance
* access to standards - all of the IPng standards will be published
as RFCs with unlimited distribution
* multicast support - IPng specifically includes multicast support
* extensibility - the use of extension headers and an expandable
header option feature will allow the introduction of new features
into IPng when needed in a way that minimizes the disruption of the
existing network
* service classes - the IPng header includes a Flow Label which may
be used to differentiate requested service classes
* mobility - the proposed IPv4 mobility functions will work with IPng
* control protocol - IPng includes the familiar IPv4 control protocol
features
* tunneling support - encapsulation of IPng or other protocols within
IPng is a basic capability described in the IPng specifications
11.2 IPv6
The IANA has assigned version number 6 to IPng. The protocol itself
will be called IPv6.
The remainder of this memo is used to describe IPv6 and its features.
This description is an overview snapshot. The standards documents
themselves should be referenced for definitive specifications. We
also make a number of specific recommendations concerning the details
of the proposed protocol, the procedures required to complete the
definition of the protocol, and the IETF working groups we feel are
necessary to accomplish the task.
12. IPv6 Overview
IPv6 is a new version of the Internet Protocol, it has been designed
as an evolutionary, rather than revolutionary, step from IPv4.
Functions which are generally seen as working in IPv4 were kept in
IPv6. Functions which don't work or are infrequently used were
removed or made optional. A few new features were added where the
functionality was felt to be necessary.
The important features of IPv6 include: [Hinden94c]
* expanded addressing and routing capabilities - The IP address size
is increased from 32 bits to 128 bits providing support for a much
greater number of addressable nodes, more levels of addressing
hierarchy, and simpler auto-configuration of addresses.
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RFC 1752 Recommendation for IPng January 1995
The scaleability of multicast routing is improved by adding a
"scope" field to multicast addresses.
A new type of address, called a "cluster address" is defined to
identify topological regions rather than individual nodes. The use
of cluster addresses in conjunction with the IPv6 source route
capability allows nodes additional control over the path their
traffic takes.
* simplified header format - Some IPv4 header fields have been
dropped or made optional to reduce the common-case processing cost
of packet handling and to keep the bandwidth overhead of the IPv6
header as low as possible in spite of the increased size of the
addresses. Even though the IPv6 addresses are four time longer
than the IPv4 addresses, the IPv6 header is only twice the size of
the IPv4 header.
* support for extension headers and options - IPv6 options are placed
in separate headers that are located in the packet between the IPv6
header and the transport-layer header. Since most IPv6 option
headers are not examined or processed by any router along a
packet's delivery path until it arrives at its final destination,
this organization facilitates a major improvement in router
performance for packets containing options. Another improvement is
that unlike IPv4, IPv6 options can be of arbitrary length and not
limited to 40 bytes. This feature plus the manner in which they are
processed, permits IPv6 options to be used for functions which were
not practical in IPv4.
A key extensibility feature of IPv6 is the ability to encode,
within an option, the action which a router or host should perform
if the option is unknown. This permits the incremental deployment
of additional functionality into an operational network with a
minimal danger of disruption.
* support for authentication and privacy - IPv6 includes the
definition of an extension which provides support for
authentication and data integrity. This extension is included as a
basic element of IPv6 and support for it will be required in all
implementations.
IPv6 also includes the definition of an extension to support
confidentiality by means of encryption. Support for this extension
will be strongly encouraged in all implementations.
Bradner & Mankin PAGE 22
RFC 1752 Recommendation for IPng January 1995
* support for autoconfiguration - IPv6 supports multiple forms of
autoconfiguration, from "plug and play" configuration of node
addresses on an isolated network to the full-featured facilities
offered by DHCP.
* support for source routes - IPv6 includes an extended function
source routing header designed to support the Source Demand Routing
Protocol (SDRP). The purpose of SDRP is to support source-initiated
selection of routes to complement the route selection provided by
existing routing protocols for both inter-domain and intra-domain
routes. [Estrin94b]
* simple and flexible transition from IPv4 - The IPv6 transition plan
is aimed at meeting four basic requirements: [Gillig94a]
- Incremental upgrade. Existing installed IPv4 hosts and routers
may be upgraded to IPv6 at any time without being dependent on
any other hosts or routers being upgraded.
- Incremental deployment. New IPv6 hosts and routers can be
installed at any time without any prerequisites.
- Easy Addressing. When existing installed IPv4 hosts or routers
are upgraded to IPv6, they may continue to use their existing
address. They do not need to be assigned new addresses.
- Low start-up costs. Little or no preparation work is needed in
order to upgrade existing IPv4 systems to IPv6, or to deploy new
IPv6 systems.
* quality of service capabilities - A new capability is added to
enable the labeling of packets belonging to particular traffic
"flows" for which the sender has requested special handling, such
as non-default quality of service or "real-time" service.
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RFC 1752 Recommendation for IPng January 1995
12.1 IPv6 Header Format
The IPv6 header, although longer than the IPv4 header, is
considerably simplified. A number of functions that were in the IPv4
header have been relocated in extension headers or dropped.
[Deering94b]
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Version - Internet Protocol version number. IPng has been assigned
version number 6. (4-bit field)
* Flow Label - This field may be used by a host to label those
packets for which it is requesting special handling by routers
within a network, such as non-default quality of service or "real-
time" service. (28-bit field)
* Payload Length - Length of the remainder of the packet following
the IPv6 header, in octets. To permit payloads of greater than 64K
bytes, if the value in this field is 0 the actual packet length
will be found in an Hop-by-Hop option. (16-bit unsigned integer)
* Next Header - Identifies the type of header immediately following
the IPv6 header. The Next Header field uses the same values as the
IPv4 Protocol field (8-bit selector field)
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RFC 1752 Recommendation for IPng January 1995
* Hop Limit - Used to limit the impact of routing loops. The Hop
Limit field is decremented by 1 by each node that forwards the
packet. The packet is discarded if Hop Limit is decremented to
zero. (8-bit unsigned integer)
* Source Address - An address of the initial sender of the packet.
(128 bit field)
* Destination Address - An address of the intended recipient of the
packet (possibly not the ultimate recipient, if an optional Routing
Header is present). (128 bit field)
12.2 Extension Headers
In IPv6, optional internet-layer information is encoded in separate
headers that may be placed between the IPv6 header and the
transport-layer header in a packet. There are a small number of such
extension headers, each identified by a distinct Next Header value.
[From a number of the documents listed in Appendix C.]
12.2.1 Hop-by-Hop Option Header
The Hop-by-Hop Options header is used to carry optional
information that must be examined by every node along a packet's
delivery path. The Hop-by-Hop Options header is identified by a
Next Header value of 0 in the IPv6 header, and has the following
format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next Header - Identifies the type of header immediately
following the Hop-by-Hop Options header. Uses the same values
as the IPv4 Protocol field. (8-bit selector)
* Hdr Ext Len - Length of the Hop-by-Hop Options header in 8-octet
units, not including the first 8 octets. (8-bit unsigned
integer)
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RFC 1752 Recommendation for IPng January 1995
* Options - Contains one or more TLV-encoded options. (Variable-
length field, of length such that the complete Hop-by-Hop
Options header is an integer multiple of 8 octets long.)
12.2.2 IPv6 Header Options
Two of the currently-defined extension headers -- the Hop-by-Hop
Options header and the End-to-End Options header -- may carry a
variable number of Type-Length-Value (TLV) encoded "options", of
the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
* Option Type - identifier of the type of option (8-bit field)
* Opt Data Len - Length of the Option Data field of this option,
in octets. (8-bit unsigned integer)
* Option Data - Option-Type-specific data. (Variable-length field)
The Option Type identifiers are internally encoded such that their
highest-order two bits specify the action that must be taken if
the processing IPv6 node does not recognize the Option Type:
00 - skip over this option and continue processing the header
01 - discard the packet
10 - discard the packet and send an ICMP Unrecognized Type message
to the packet's Source Address, pointing to the unrecognized
Option Type
11 - undefined.
In the case of Hop-by-Hop options only, the third-highest-order
bit of the Option Type specifies whether or not the Option Data of
this option shall be included in the integrity assurance
computation performed when an Authentication header is present.
Option data that changes en route must be excluded from that
computation.
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RFC 1752 Recommendation for IPng January 1995
12.2.3 Routing Header
The Routing header is used by an IPv6 source to list one or more
intermediate nodes (or topological clusters) to be "visited" on
the way to a packet's destination. This particular form of the
Routing Header is designed to support SDRP. [Estrin94b]
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header |Routing Type=1 |M|F| Reserved | SrcRouteLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NextHopPtr | Strict/Loose Bit Mask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Source Route .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next Header - Identifies the type of header immediately
following the Routing Header. Uses the same values as the IPv4
Protocol field. (8-bit selector)
* Routing Type - Indicates the type of routing supported by this
header. Value must be 1.
* MRE flag - Must Report Errors. If this bit is set to 1, and a
router can not further forward a packet (with an incompletely
traversed source route), as specified in the Source Route, the
router must generate an ICMP error message. If this bit is set
to 0, and a router can not further forward a packet (with an
incompletely traversed source route), as specified in the Source
Route, the router should not generate an ICMP error message.
* F flag - Failure of Source Route Behavior. If this bit it set
to 1, it indicates that if a router can not further forward a
packet (with an incompletely traversed source route), as
specified in the Source Route, the router must set the value of
the Next Hop Pointer field to the value of the Source Route
Length field, so that the subsequent forwarding will be based
solely on the destination address. If this bit is set to 0, it
indicates that if a router can not further forward a packet
(with an incompletely traversed source route), as specified in
the Source Route, the router must discard the packet.
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RFC 1752 Recommendation for IPng January 1995
* Reserved - Initialized to zero for transmission; ignored on
reception.
* SrcRouteLen - Source Route Length - Number of source route
elements/hops in the SDRP Routing header. Length of SDRP
routing header can be calculated from this value (length =
SrcRouteLen * 16 + 8) This field may not exceed a value of 24.
(8 bit unsigned integer)
* NextHopPtr - Next Hop Pointer- Index of next element/hop to be
processed; initialized to 0 to point to first element/hop in the
source route. When Next Hop Pointer is equal to Source Route
Length then the Source Route is completed. (8 bit unsigned
integer)
* Strict/Loose Bit Mask - The Strict/Loose Bit Mask is used when
making a forwarding decision. If the value of the Next Hop
Pointer field is N, and the N-th bit in the Strict/Loose Bit
Mask field is set to 1, it indicates that the next hop is a
Strict Source Route Hop. If this bit is set to 0, it indicates
that the next hop is a Loose Source Route Hop. (24 bit
bitpattern)
* Source Route - A list of IPv6 addresses indicating the path that
this packet should follow. A Source Route can contain an
arbitrary intermix of unicast and cluster addresses. (integral
multiple of 128 bits)
12.2.4 Fragment Header
The Fragment header is used by an IPv6 source to send payloads
larger than would fit in the path MTU to their destinations.
(Note: unlike IPv4, fragmentation in IPv6 is performed only by
source nodes, not by routers along a packet's delivery path) The
Fragment header is identified by a Next Header value of 44 in the
immediately preceding header, and has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next Header - Identifies the type of header immediately
following the Fragment header. Uses the same values as the IPv4
Protocol field. (8 bit selector)
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RFC 1752 Recommendation for IPng January 1995
* Reserved, Res - Initialized to zero for transmission; ignored on
reception.
* Fragment Offset - The offset, in 8-octet units, of the following
payload, relative to the start of the original, unfragmented
payload. (13-bit unsigned integer)
* M flag - 1 = more fragments; 0 = last fragment.
* Identification - A value assigned to the original payload that
is different than that of any other fragmented payload sent
recently with the same IPv6 Source Address, IPv6 Destination
Address, and Fragment Next Header value. (If a Routing header
is present, the IPv6 Destination Address is that of the final
destination.) The Identification value is carried in the
Fragment header of all of the original payload's fragments, and
is used by the destination to identify all fragments belonging
to the same original payload. (32 bit field)
12.2.5 Authentication Header
The Authentication header is used to provide authentication and
integrity assurance for IPv6 packets. Non-repudiation may be
provided by an authentication algorithm used with the
Authentication header, but it is not provided with all
authentication algorithms that might be used with this header.
The Authentication header is identified by a Next Header value of
51 in the immediately preceding header, and has the following
format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Auth Data Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Security Association ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Authentication Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next Header - Identifies the type of header immediately
following the Authentication header. Uses the same values as
the IPv4 Protocol field. (8-bit selector)
* Auth Data Len - Length of the Authentication Data field in 8-
octet units. (8-bit unsigned integer)
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RFC 1752 Recommendation for IPng January 1995
* Reserved - Initialized to zero for transmission; ignored on
reception.
* Security Assoc. ID - When combined with the IPv6 Source Address,
identifies to the receiver(s) the pre-established security
association to which this packet belongs. (32 bit field)
* Authentication Data - Algorithm-specific information required
to authenticate the source of the packet and assure its
integrity, as specified for the pre-established security
association. (Variable-length field, an integer multiple of 8
octets long.)
12.2.6 Privacy Header
The Privacy Header seeks to provide confidentiality and integrity
by encrypting data to be protected and placing the encrypted data
in the data portion of the Privacy Header. Either a transport-
layer (e.g., UDP or TCP) frame may be encrypted or an entire IPv6
datagram may be encrypted, depending on the user's security
requirements. This encapsulating approach is necessary to provide
confidentiality for the entire original datagram. If present, the
Privacy Header is always the last non-encrypted field in a packet.
The Privacy Header works between hosts, between a host and a
security gateway, or between security gateways. This support for
security gateways permits trustworthy networks to exist without
the performance and monetary costs of security, while providing
security for traffic transiting untrustworthy network segments.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Security Association Identifier (SAID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Initialization Vector .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header* | Length* | Reserved* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Protected Data* +-+-+-+-+-+-+-+-+-+-+
| | trailer* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*encrypted
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RFC 1752 Recommendation for IPng January 1995
* Security Association Identifier (SAID) - Identifies the security
association for this datagram. If no security association has
been established, the value of this field shall be 0x0000. A
security association is normally one-way. An authenticated
communications session between two hosts will normally have two
SAIDs in use (one in each direction). The receiving host uses
the combination of SAID value and originating address to
distinguish the correct association. (32 bit value)
* Initialization Vector - This field is optional and its value
depends on the SAID in use. For example, the field may contain
cryptographic synchronization data for a block oriented
encryption algorithm. It may also be used to contain a
cryptographic initialization vector. A Privacy Header
implementation will normally use the SAID value to determine
whether this field is present and, if it is, the field's size
and use. (presence and length dependent on SAID)
* Next Header - encrypted - Identifies the type of header
immediately following the Privacy header. Uses the same values
as the IPv4 Protocol field. (8 bit selector)
* Reserved - encrypted - Ignored on reception.
* Length - encrypted - Length of the Privacy Header in 8-octet
units, not including the first 8 octets. (8-bit unsigned
integer)
* Protected Data - encrypted - This field may contain an entire
encapsulated IPv6 datagram, including the IPv6 header, a
sequence of zero or more IPv6 options, and a transport-layer
payload, or it may just be a sequence of zero or more IPv6
options followed by a transport-layer payload. (variable
length)
* trailer (Algorithm-dependent Trailer) - encrypted - A field
present to support some algorithms which need to have padding
(e.g., to a full cryptographic block size for block-oriented
encryption algorithms) or for storage of authentication data for
use with a encryption algorithm that provides confidentiality
without authentication. It is present only when the algorithm
in use requires such a field. (presence and length dependent on
SAID)
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RFC 1752 Recommendation for IPng January 1995
12.2.7 End-to-End Option Header
The End-to-End Options header is used to carry optional
information that needs to be examined only by a packet's
destination node(s). The End-to-End Options header is identified
by a Next Header value of TBD in the immediately preceding header,
and has the same format as the Hop-by-Hop Option Header except for
the ability to exclude an option from the authentication integrity
assurance computation.
13. IPng Working Group
We recommend that a new IPng Working Group be formed to produce
specifications for the core functionality of the IPv6 protocol suite.
The working group will carry out the recommendations of the IPng Area
Directors as outlined at the July 1994 IETF and in this memo. We
recommend that this working group be chaired by Steve Deering of
Xerox PARC and Ross Callon of Wellfleet.
The primary task of the working group is to produce a set of
documents that define the basic functions, interactions, assumptions,
and packet formats for IPv6. We recommend that Robert Hinden of Sun
Microsystems be the editor for these documents. The documents listed
in Appendix C will be used by the working group to form the basis of
the final document set.
The work of the IPng Working Group includes:
* complete the IPv6 overview document
* complete the IPv6 detailed operational specification
* complete the IPv6 Addressing Architecture specification
* produce specifications for IPv6 encapsulations over various media
* complete specifications for the support of packets larger than 64KB
* complete specifications of the DNS enhancements required to support
IPv6
* complete specification of ICMP, IGMP and router discovery for
support of IPv6.
* complete specification of path MTU discovery for IPv6
* complete specifications of IPv6 in IPv6 tunneling
* complete the suggested address format and assignment plan
* coordinate with the Address Autoconfiguration Working Group
* coordinate with the NGTRANS and TACIT Working Groups
* complete specifications of authentication and privacy support
headers
Bradner & Mankin PAGE 32
RFC 1752 Recommendation for IPng January 1995
The working group should also consider a few selected enhancements
including:
* consider ways to compress the IPv6 header in the contexts of native
IPv6, multiple IPv6 packets in a flow, and encapsulated IPv6
* consider specifying support for a larger minimum MTU
14. IPng Reviewer
Currently it is the task of the IPng Area Directors, the IPng
Directorate and the chairs of the proposed ipng working group to
coordinate the activities of the many parallel efforts currently
directed towards different aspects of IPng. While this is possible
and currently seems to be working well it can not be maintained over
the long run because, among other reasons, the IPng Area will be
dissolved eventually and its Directorate disbanded. It will also
become much more difficult as IPng related activities start up in
other IETF areas.
We recommend that an IPng Reviewer be appointed to be specifically
responsible for ensuring that a consistent view of IPv6 is maintained
across the related working groups. We feel that this function is
required due to the complex nature of the interactions between the
parts of the IPng effort and due to the distribution of the IPng
related work amongst a number of IETF areas. We recommend that Dave
Clark of MIT be offered this appointment.
This would be a long-term task involving the review of on-going
activities. The aim is not for the IPng Reviewer to make
architectural decisions since that is the work of the various working
groups, the IAB, and the IETF as a whole.. The aim is to spot gaps or
misunderstandings before they reach the point where functionality or
interworkability is threatened.
15. Address Autoconfiguration
As data networks become more complex the need to be able to bypass at
least some of the complexity and move towards "plug and play" becomes
ever more acute. The user can not be expected to be able to
understand the details of the network architecture or know how to
configure the network software in their host. In the ideal case, a
user should be able to unpack a new computer, plug it into the local
network and "just" have it work without requiring the entering of any
special information. Security concerns may restrict the ability to
offer this level of transparent address autoconfiguration in some
environments but the mechanisms must be in place to support whatever
level of automation which the local environment feels comfortable
with.
Bradner & Mankin PAGE 33
RFC 1752 Recommendation for IPng January 1995
The basic requirement of "plug and play" operation is that a host
must be able to acquire an address dynamically, either when attaching
to a network for the first time or when the host needs to be
readdressed because the host moved or because the identity of the
network has changed. There are many other functions required to
support a full "plug and play" environment. [Berk94] Most of these
must be addressed outside of the IPv6 Area but a focused effort to
define a host address autoconfiguration protocol is part of the IPv6
process.
We recommend that a new Address Autoconfiguration Working Group
(addrconf) be formed with Dave Katz of Cisco Systems and Sue Thomson
of Bellcore as co-chairs. The purpose of this working group is to
design and specify a protocol for allocating addresses dynamically to
IPv6 hosts. The address configuration protocol must be suitable for
a wide range of network topologies, from a simple isolated network to
a sophisticated globally connected network. It should also allow for
varying levels of administrative control, from completely automated
operation to very tight oversight.
The scope of this working group is to propose a host address
autoconfiguration protocol which supports the full range of
topological and administrative environments in which IPv6 will be
used. It is the intention that, together with IPv6 system discovery,
the address autoconfiguration protocol will provide the minimal
bootstrapping information necessary to enable hosts to acquire
further configuration information (such as that provided by DHCP in
IPv4). The scope does not include router configuration or any other
host configuration functions. However, it is within the scope of the
working group to investigate and document the interactions between
this work and related functions including system discovery, DNS
autoregistration, service discovery, and broader host configuration
issues, to facilitate the smooth integration of these functions.
[Katz94a]
The working group is expected to complete its work around the end of
1994 and disband at that time. The group will use "IPv6 Address
Autoconfiguration Architecture" [Katz94b] draft document as the basis
of their work.
16. Transition
The transition of the Internet from IPv4 to IPv6 has to meet two
separate needs. There is a short term need to define specific
technologies and methods to transition IPv4 networks, including the
Internet, into IPv6 networks and an IPv6 Internet. There is also a
long term need to do broad-based operational planning for transition,
including developing methods to allow decentralized migration
Bradner & Mankin PAGE 34
RFC 1752 Recommendation for IPng January 1995
strategies, understanding the ramifications of a long period of
coexistence when both protocols are part of the basic infrastructure,
developing an understanding of the type and scope of architectural
and interoperability testing that will be required to ensure a
reliable and manageable Internet in the future.
16.1 Transition - Short Term
Any IPng transition plan must take into account the realities of what
types of devices vendors will build and network managers will deploy.
The IPng transition plan must define the procedures required to
successfully implement the functions which vendors will be likely to
include in their devices. This is the case even if there are good
arguments to recommend against a particular function, header
translation for example. If products will exist it is better to have
them interoperate than not.
We recommend that a new IPng Transition (NGTRANS) Working Group be
formed with Bob Gilligan of Sun Microsystems and xxx of yyy as co-
chairs to design the mechanisms and procedures to support the
transition of the Internet from IPv4 to IPv6 and to give advice on
what procedures and techniques are preferred.
The work of the group will fall into three areas:
* Define the processes by which the Internet will make the transition
from IPv4 to IPv6. As part of this effort, the group will produce
a document explaining to the general Internet community what
mechanisms will be employed in the transition, how the transition
will work, the assumptions about infrastructure deployment inherent
in the operation of these mechanisms, and the types of
functionality that applications developers will be able to assume
as the protocol mix changes over time.
* Define and specify the mandatory and optional mechanisms that
vendors should implement in hosts, routers, and other components of
the Internet in order for the transition to be carried out. Dual-
stack, encapsulation and header translation mechanisms must all be
defined, as well as the interaction between hosts using different
combinations of these mechanisms. The specifications produced will
be used by people implementing these IPv6 systems.
* Articulate a concrete operational plan for the Internet to make the
transition from IPv4 to IPv6. The result of this work will be a
transition plan for the Internet that network operators and
Internet subscribers can execute.
[Gillig94c]
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RFC 1752 Recommendation for IPng January 1995
The working group is expected to complete its work around the end of
1994 and disband at that time. The group will use the "Simple SIPP
Transition (SST)" [Gilig94a] overview document as the starting point
for its work.
16.2 Transition - Long Term
There are a number of transition related topics in addition to
defining the specific IPv4 to IPv6 mechanisms and their deployment,
operation and interaction. The ramifications and procedures of
migrating to a new technology or to a new version of an existing
technology must be fully understood.
We recommend that the Transition and Coexistence Including Testing
(TACIT) Working Group, which was started a few months ago, explore
some of the basic issues associated with the deployment of new
technology into an established Internet. The TACIT Working Group
will focus on the generic issues of transition and will not limit
itself to the upcoming transition to IPv6 because, over time,
enhancements to IPv6 (IPv6ng) will be developed and accepted. At
that point they will need to be deployed into the then existing
Internet. The TACIT Working Group will be more operationally
oriented than the NGTRANS Working Group and will continue well into
the actual IPv6 transition.
The main areas of exploration are:
* Make the transition from a currently deployed protocol to a new
protocol while accommodating heterogeneity and decentralized
management.
* Since it is often difficult or impossible to replace all legacy
systems or software, it is important to understand the
characteristics and operation of a long period of coexistence
between a new protocol and the existing protocol.
* The Internet must now be considered a utility. We are far removed
from a time when a new technology could be deployed to see if it
would work in large scale situations. Rigorous architectural and
interoperability testing must be part of the predeployment phase of
any proposed software for the Internet. Testing the scaling up
behaviors and robustness of a new protocol will offer particular
challenges. The WG should determine if there are lessons to be
learned from: OSPF, BGP4 and CIDR Deployment, the AppleTalk 1 to 2
transition, DECnet Phase 4 to Phase 5 planning and transition,
among others.
Bradner & Mankin PAGE 36
RFC 1752 Recommendation for IPng January 1995
The TACIT Working Group will explore each of these facets of the
deployment of new technology and develop a number of documents to
help guide users and managers of affected data networks and provide
to the IETF:
* Detailed descriptions of problem areas in transition and
coexistence, both predicted, based on lessons learned, and observed
as the IPv6 process progresses.
* Recommendations for specific testing procedures.
* Recommendations for coexistence operations procedures
* Recommendations for the smoothing of decentralized transition
planning.
[Huston94]
17. Other Address Families
There are many environments in which there are one or more network
protocols already deployed or where a significant planning effort has
been undertaken to create a comprehensive network addressing plan. In
such cases there may be a temptation to integrate IPv6 into the
environment by making use of an existing addressing plan to define
all or part of the IPv6 addresses. The advantage of doing this is
that it permits unified management of address space among multiple
protocol families. The use of common addresses can help facilitate
transition from other protocols to IPv6.
If the existing addresses are globally unique and assigned with
regard to network topology this may be a reasonable idea. The IETF
should work with other organizations to develop algorithms that could
be used to map addresses between IPv6 and other environments. The
goal for any such mapping must be to provide an unambiguous 1 to 1
map between individual addresses.
Suggestions have been made to develop mapping algorithms for Novell
IPX addresses, some types of OSI NSAPs, E164 addresses and SNA
addresses. Each of these possibilities should be carefully examined
to ensure that use of such an algorithm solves more problems than it
creates. In some cases it may be better to recommend either that a
native IPng addressing plan be developed instead, or that an IPv6
address be used within the non-IP environment. [Carpen94b]
We recommend that, in conjunction with other organizations,
recommendations about the use of non-IPv6 addresses in IPv6
environments and IPv6 addresses in non-IPv6 environments be
developed.
Bradner & Mankin PAGE 37
RFC 1752 Recommendation for IPng January 1995
18. Impact on Other IETF Standards
Many current IETF standards are affected by IPv6. At least 27 of the
current 51 full Internet Standards must be revised for IPv6, along
with at least 6 of the 20 Draft Standards and at least 25 of the 130
Proposed Standards. [Postel94]
In some cases the revisions consist of simple changes to the text,
for example, in a number of RFCs an IP address is referred to in
passing as a "32 bit IP address" even though IP addresses are not
directly used in the protocol being defined. All of the standards
track documents will have to be checked to see if they contain such
references.
In most of the rest of the cases revisions to the protocols,
including packet formats, will be required. In many of these cases
the address is just being carried as a data element and a revised
format with a larger field for the address will have no effect on the
functional paradigm.
In the remaining cases some facet of the operation of the protocol
will be changed as a result of IPv6. For example, the security and
source route mechanisms are fundamentally changed from IPv4 with
IPv6. Protocols and applications that relied on the IPv4
functionality will have to be redesigned or rethought to use the
equivalent function in IPv6.
In a few cases this opportunity should be used to determine if some
of the RFCs should be moved to historic, for example EGP [Mills84]
and IP over ARCNET. [Provan91]
The base IPng Working Group will address some of these, existing IETF
working groups can work on others, while new working groups must be
formed to deal with a few of them. The IPng Working Group will be
responsible for defining new versions of ICMP, ARP/RARP, and UDP. It
will also review RFC 1639, "FTP Operation Over Big Address Records
(FOOBAR)" [Piscit94] and RFC 1191 "Path MTU Discovery" [Mogul90]
Existing working groups will examine revisions for some of the
routing protocols: RIPv2, IS-IS, IDRP and SDRP. A new working group
may be required for OSPF.
The existing DHCP Working Group may be able to revise DHCP and
examine BOOTP.
Bradner & Mankin PAGE 38
RFC 1752 Recommendation for IPng January 1995
A TCPng Working Group will be formed soon, and new working groups
will have to be formed to deal with standards such as SNMP, DNS, NTP,
NETbios, OSI over TCP, Host Requirements, and Kerberos as well as
reviewing most of the RFCs that define IP usage over various media.
In addition to the standards track RFCs mentioned above there are
many Informational and Experimental RFCs which would be affected as
well as numerous Internet Drafts (and those standards track RFCs that
we missed).
We recommend that the IESG commission a review of all standards track
RFCs to ensure that a full list of affected documents is compiled. We
recommend that the IESG charge current IETF working groups with the
task of understanding the impact of IPv6 on their proposals and,
where appropriate, revise the documents to include support for IPv6.
We recommend that the IESG charter new working groups where required
to revise other standards RFCs.
19. Impact on non-IETF standards and on products
Many products and user applications which rely on the size or
structure of IPv4 addresses will need to be modified to work with
IPv6. While the IETF can facilitate an investigation of the impacts
of IPv6 on non-IETF standards and products, the primary
responsibility for doing so resides in the other standards bodies and
the vendors.
Examples of non-IETF standards that are effected by IPv6 include the
POSIX standards, Open Software Foundation's DCE and DME, X-Open, Sun
ONC, the Andrew File System and MIT's Kerberos. Most products that
provide specialized network security including firewall-type devices
are among those that must be extended to support IPv6.
20. APIs
It is traditional to state that the IETF does not "do" APIs. While
there are many reasons for this, the one most commonly referenced is
that there are too many environments where TCP/IP is used, too many
different operating systems, programming languages, and platforms.
The feeling is that the IETF should not get involved in attempting to
define a language and operating system independent interface in the
face of such complexity.
We feel that this historical tendency for the IETF to avoid dealing
with APIs should be reexamined in the case of IPv6. We feel that in
a few specific cases the prevalence of a particular type of API is
such that a single common solution for the modifications made
Bradner & Mankin PAGE 39
RFC 1752 Recommendation for IPng January 1995
necessary by IPv6 should be documented.
We recommend that Informational RFCs be solicited or developed for
these few cases. In particular, the Berkeley-style sockets
interface, the UNIX TLI and XTI interfaces, and the WINSOCK
interfaces should be targeted. A draft document exists which could
be developed into the sockets API description. [Gillig94b]
21. Future of the IPng Area and Working Groups
In our presentation at the Houston IETF meeting we stated that the
existing IPng proposal working groups would not be forced to close
down after the recommendation was made. Each of them has been
working on technologies that may have applications in addition to
their IPng proposal and these technologies should not be lost.
Since the Toronto IETF meeting the existing IPng working groups have
been returned to the Internet Area. The group members may decide to
close down the working groups or to continue some of their efforts.
The charters of the working groups must be revised if they choose to
continue since they would no longer be proposing an IPng candidate.
In Toronto the chairs of the SIPP Working Group requested that the
SIPP Working Group be concluded. The chairs of the TUBA Working
Group requested that the TUBA working group be understood to be in
hiatus until a number of the documents in process were completed, at
which time they would request that the working group be concluded.
We recommend that the IPng Area and its Directorate continue until
the basic documents have entered the standards track in late 1994 or
early 1995 and that after such time the area be dissolved and those
IPng Area working groups still active be moved to their normal IETF
areas.
22. Security Considerations
The security of the Internet has long been questioned. It has been
the topic of much press coverage, many conferences and workshops.
Almost all of this attention has been negative, pointing out the many
places where the level of possible security is far less than that
deemed necessary for the current and future uses of the Internet. A
number of the RFC 1550 White Papers specifically pointed out the
requirement to improve the level of security available [Adam94,
Bell94b, Brit94, Green94, Vecchi94, Flei94] as does "Realizing the
Information Future". [Nat94]
Bradner & Mankin PAGE 40
RFC 1752 Recommendation for IPng January 1995
In February of 1994, the IAB convened a workshop on security in the
Internet architecture. The report of this workshop [IAB94] includes
an exploration of many of the security problem areas and makes a
number of recommendations to improve the level of security that the
Internet offers its users.
We feel that an improvement in the basic level of security in the
Internet is vital to its continued success. Users must be able to
assume that their exchanges are safe from tampering, diversion and
exposure. Organizations that wish to use the Internet to conduct
business must be able to have a high level of confidence in the
identity of their correspondents and in the security of their
communications. The goal is to provide strong protection as a matter
of course throughout the Internet.
As the IAB report points out, many of the necessary tools are not a
function of the internetworking layer of the protocol. These higher
level tools could make use of strong security features in the
internetworking layer if they were present. While we expect that
there will be a number of special high-level security packages
available for specific Internet constituencies, support for basic
packet-level authentication will provide for the adoption of a much
needed, widespread, security infrastructure throughout the Internet.
It is best to separate the support for authentication from the
support for encryption. One should be able to use the two functions
independently. There are some applications in which authentication
of a corespondent is sufficient and others where the data exchanged
must be kept private.
It is our recommendation that IPv6 support packet authentication as a
basic and required function. Applications should be able to rely on
support for this feature in every IPv6 implementation. Support for a
specific authentication algorithm should also be mandated while
support for additional algorithms should be optional.
Thus we recommend that support for the Authentication Header be
required in all compliant IPv6 implementations.
We recommend that support for a specific authentication algorithm be
required. The specific algorithm should be determined by the time
the IPv6 documents are offered as Proposed Standards.
We recommend that support for the Privacy Header be required in IPv6
implementations.
Bradner & Mankin PAGE 41
RFC 1752 Recommendation for IPng January 1995
We recommend that support for a privacy authentication algorithm be
required. The specific algorithm should be determined by the time the
IPv6 documents are offered as Proposed Standards.
Clearly, a key management infrastructure will be required in order to
enable the use of the authentication and encryption headers.
However, defining such an infrastructure is outside the scope of the
IPv6 effort. We do note that there are on-going IETF activities in
this area. The IPv6 transition working groups must coordinate with
these activities.
Just as clearly, the use of authentication and encryption may add to
the cost and impact the performance of systems but the more secure
infrastructure is worth the penalty. Whatever penalty there is
should also decrease in time with improved software and hardware
assistance.
The use of firewalls is increasing on the Internet. We hope that the
presence of the authentication and privacy features in IPv6 will
reduce the need for firewalls, but we do understand that they will
continue to be used for the foreseeable future. In this light, we
feel that clear guidance should be given to the developers of
firewalls on the best ways to design and configure them when working
in an IPv6 environment.
We recommend that an "IPv6 framework for firewalls" be developed.
This framework should explore the ways in which the Authentication
Header can be used to strengthen firewall technology and detail how
the IPv6 packet should be analyzed by a firewall.
Some aspects of security require additional study. For example, it
has been pointed out [Vecchi94] that, even in non-military
situations, there are places where procedures to thwart traffic
analysis will be required. This could be done by the use of
encrypted encapsulation, but this and other similar requirements must
be addressed on an on-going basis by the Security Area of the IETF.
The design of IPv6 must be flexible enough to support the later
addition of such security features.
We believe that IPv6 with its inherent security features will provide
the foundation upon which the Internet can continue to expand its
functionality and user base.
Bradner & Mankin PAGE 42
RFC 1752 Recommendation for IPng January 1995
23. Authors' Addresses
Scott Bradner
Harvard University
10 Ware St.
Cambridge, MA 02138
Phone: +1 617 495 3864
EMail: sob@harvard.edu
Allison Mankin
USC/Information Sciences Institute
4350 North Fairfax Drive, Suite 400
Arlington, VA 22303
Phone: +1 703-807-0132
EMail: mankin@isi.edu
Bradner & Mankin PAGE 43
RFC 1752 Recommendation for IPng January 1995
Appendix A - Summary of Recommendations
5.3 Address Assignment Policy Recommendations
changes in address assignment policies are not recommended
reclamation of underutilized assigned addresses is not currently
recommended
efforts to renumber significant portions of the Internet are not
currently recommended
recommend consideration of assigning CIDR-type address blocks out
of unassigned Class A addressees
11. IPng Recommendation
recommend that "Simple Internet Protocol Plus (SIPP) Spec. (128
bit ver)" [Deering94b] be adopted as the basis for IPng
recommend that the documents listed in Appendix C be the basis of
IPng
13. IPng Working Group
recommend that an IPng Working Group be formed, chaired by Steve
Deering and Ross Callon
recommend that Robert Hinden be the document editor for the IPng
effort
14. IPng Reviewer
recommend that an IPng Reviewer be appointed and that Dave Clark
be that reviewer
15. Address Autoconfiguration
recommend that an Address Autoconfiguration Working Group be
formed, chaired by Dave Katz and Sue Thomson
16.1 Transition - Short Term
recommend that an IPng Transition Working Group be formed, chaired
by Bob Gilligan and TBA
16.2 Transition - Long Term
recommend that the Transition and Coexistence Including Testing
Working Group be chartered
17. Other Address Families
recommend that recommendations about the use of non-IPv6 addresses
in IPv6 environments and IPv6 addresses in non-IPv6
environments be developed
18. Impact on Other IETF Standards
recommend the IESG commission a review of all standards track RFCs
recommend the IESG charge current IETF working groups with the
task of understanding the impact of IPng on their proposals
and, where appropriate, revise the documents to include support
for IPng
recommend the IESG charter new working groups where required to
revise other standards RFCs
20. APIs
recommend that Informational RFCs be developed or solicited for a
few of the common APIs
Bradner & Mankin PAGE 44
RFC 1752 Recommendation for IPng January 1995
21. Future of the IPng Area and Working Groups
recommend that the IPng Area and Area Directorate continue until
main documents are offered as Proposed Standards in late 1994
22. Security Considerations
recommend that support for the Authentication Header be required
recommend that support for a specific authentication algorithm be
required
recommend that support for the Privacy Header be required
recommend that support for a specific privacy algorithm be
required
recommend that an "IPng framework for firewalls" be developed
Appendix B - IPng Area Directorate
J. Allard - Microsoft <jallard@microsoft.com>
Steve Bellovin - AT&T <smb@research.att.com>
Jim Bound - Digital <bound@zk3.dec.com>
Ross Callon - Wellfleet <rcallon@wellfleet.com>
Brian Carpenter - CERN <brian.carpenter@cern.ch>
Dave Clark - MIT <ddc@lcs.mit.edu >
John Curran - NEARNET <curran@nic.near.net>
Steve Deering - Xerox <deering@parc.xerox.com>
Dino Farinacci - Cisco <dino@cisco.com>
Paul Francis - NTT <francis@slab.ntt.jp>
Eric Fleischmann - Boeing <ericf@atc.boeing.com>
Mark Knopper - Ameritech <mak@aads.com>
Greg Minshall - Novell <minshall@wc.novell.com>
Rob Ullmann - Lotus <ariel@world.std.com>
Lixia Zhang - Xerox <lixia@parc.xerox.com>
Daniel Karrenberg of RIPE joined the Directorate when it was formed
but had to withdraw due to the demands of his day job.
Since the Toronto IETF meeting Paul Francis has resigned from the
Directorate to pursue other interests. Robert Hinden of Sun
Microsystems and Yakov Rekhter of IBM joined.
Bradner & Mankin PAGE 45
RFC 1752 Recommendation for IPng January 1995
Appendix C - Documents Referred to the IPng Working Groups
[Deering94b] Deering, S., "Simple Internet Protocol Plus (SIPP) Spec.
(128 bit ver)", Work in Progress.
[Francis94] Francis, P., "SIPP Addressing Architecture", Work in
Progress.
[Rekhter94] Rekhter, Y., and T. Li, "An Architecture for IPv6 Unicast
Address Allocation", Work in Progress.
[Gillig94a] Gilligan, R., "Simple SIPP Transition (SST) Overview",
Work in Progress.
[Gillig94b] Gilligan, R., Govindan, R., Thomson, S., and J. Bound,
"SIPP Program Interfaces for BSD Systems", Work in Progress.
[Atkins94a] Atkinson, R., "SIPP Security Architecture", Work in
Progress.
[Atkins94b] Atkinson, R., "SIPP Authentication Header", Work in
Progress.
[Ford94b] Ford, P., Li, T., and Y. Rekhter, "SDRP Routing Header for
SIPP-16", Work in Progress.
[Hinden94c] Hinden, R., "IP Next Generation Overview", Work in
Progress.
Appendix D - IPng Proposal Overviews
[Ford94a] Ford, P., and M. Knopper, "TUBA as IPng: A White Paper",
Work in Progress.
[Hinden94a] Hinden, R., "Simple Internet Protocol Plus White Paper",
RFC 1710, Sun Microsystems, October 1994.
[McGovern94] McGovern, M., and R. Ullmann, "CATNIP: Common
Architecture for the Internet", RFC 1707, Sunspot Graphics, Lotus
Development Corp., October 1994.
Bradner & Mankin PAGE 46
RFC 1752 Recommendation for IPng January 1995
Appendix E - RFC 1550 White Papers
[Adam94] Adamson, B., "Tactical Radio Frequency Communication
Requirements for IPng", RFC 1677, NRL, August 1994.
[Bello94a] Bellovin, S., "On Many Addresses per Host", RFC 1681, AT&T
Bell Laboratories, August 1994.
[Bello94b] Bellovin, S., "Security Concerns for IPng", RFC 1675, AT&T
Bell Laboratories, August 1994.
[Bound94] Bound, J., "IPng BSD Host Implementation Analysis", RFC
1682, Digital Equipment Corporation, August 1994.
[Brazd94] Brazdziunas, C., "IPng Support for ATM Services", RFC 1680,
Bellcore, August 1994.
[Britt94] Britton, E., and J. Tavs, "IPng Requirements of Large
Corporate Networks", RFC 1678, IBM, August 1994.
[Brownl94] Brownlee, J., "Accounting Requirements for IPng", RFC
1672, University of Auckland, August 1994.
[Carpen94a] Carpenter, B., "IPng White Paper on Transition and Other
Considerations", RFC 1671, CERN, August 1994.
[Chiappa94] Chiappa, N., "IPng Technical Requirements Of the Nimrod
Routing and Addressing Architecture", RFC 1753, December 1994.
[Clark94] Clark, R., Ammar, M., and K. Calvert, "Multiprotocol
Interoperability In IPng", RFC 1683, Georgia Institute of
Technology, August 1994.
[Curran94] Curran, J., "Market Viability as a IPng Criteria", RFC
1669, BBN, August 1994.
[Estrin94a] Estrin, D., Li, T., and Y. Rekhter, "Unified Routing
Requirements for IPng", RFC 1668, USC, cisco Systems, IBM, August
1994.
[Fleisch94] Fleischman, E., "A Large Corporate User's View of IPng",
RFC 1687, Boeing Computer Services, August 1994.
[Green94] Green, D., Irey, P., Marlow, D., and K. O'Donoghue, "HPN
Working Group Input to the IPng Requirements Solicitation", RFC
1679, NSWC-DD, August 1994.
Bradner & Mankin PAGE 47
RFC 1752 Recommendation for IPng January 1995
[Ghisel94] Ghiselli, A., Salomoni, D., and C. Vistoli, "INFN
Requirements for an IPng", RFC 1676, INFN/CNAF, August 1994.
[Heager94] Heagerty, D., "Input to IPng Engineering Considerations",
RFC 1670, CERN, August 1994.
[Simpson94] Simpson, W. "IPng Mobility Considerations", RFC 1688,
Daydreamer, August 1994.
[Skelton94] Skelton, R., "Electric Power Research Institute Comments
on IPng", RFC 1673, EPRI, August 1994.
[Syming94] Symington, S., Wood, D., and J. Pullen, "Modeling and
Simulation Requirements for IPng", RFC 1667, MITRE, George Mason
University, August 1994.
[Taylor94] Taylor, M., "A Cellular Industry View of IPng", RFC 1674,
CDPD Consortium, August 1994.
[Vecchi94] Vecchi, M., "IPng Requirements: A Cable Television
Industry Viewpoint", RFC 1686, Time Warner Cable, August 1994.
Appendix F - Additional References
[Almqu92] Almquist, P., "Minutes of the Selection Criteria BOF",
Washington DC IETF, November 1992, (ietf/nov92/select-minutes-
92nov.txt).
[Berkow94] Berkowitz, H., "IPng and Related Plug-and-Play Issues and
Requirements", Work in Progress, September 1994.
[Bos94] Bos, E. J., "Minutes of the Address Lifetime Expectations BOF
(ALE)", Seattle IETF, March 1994, (ietf/ale/ale-minutes-
94mar.txt).
[Big] Archives of the big-internet mailing list, on munnari.oz.au in
big-internet/list-archives.
[Bradner93] Bradner, S., and A. Mankin, "IP: Next Generation (IPng)
White Paper Solicitation", RFC 1550, Harvard University, NRL,
December 1993.
[Callon87] Callon, R., "A Proposal for a Next Generation Internet
Protocol", Proposal to X3S3, December 1987.
[Callon92a] Callon, R., "CNAT", Work in Progress.
[Callon92b] Callon, R., "Simple CLNP", Work in Progress.
Bradner & Mankin PAGE 48
RFC 1752 Recommendation for IPng January 1995
[Callon92c] Callon, R., "TCP and UDP with Bigger Addresses (TUBA), A
Simple Proposal for Internet Addressing and Routing", RFC 1347,
DEC, June 1992.
[Carpen93] Carpenter, B. and T. Dixon, "Minutes of the IPng Decision
Process BOF (IPDECIDE)", /ietf/93jul/ipdecide-minutes-93jul.txt,
August 1993.
[Carpen94b] Carpenter, B, and J. Bound, "Recommendations for OSI NSAP
usage in IPv6", Work in Progress.
[Chiappa91] Chiappa, J., "A New IP Routing and Addressing
Architecture", Work in Progress.
[Clark91] Clark, D., Chapin, L., Cerf, V., Braden, R., and R. Hobby,
"Towards the Future Internet Architecture", RFC 1287, MIT, BBN,
CNRI, ISI, UC Davis, December 1991.
[Deering92] Deering, S., "The Simple Internet Protocol", Big-Internet
mailing list, 22 Sept. 1992.
[Deering94a] Deering, S., and P. Francis, Message to sipp mailing
list, 31 May 1994.
[Estrin94b] Estrin, D., Zappala, D., Li, T., Rekhter, Y., and K.
Varadhan, "Source Demand Routing: Packet Format and Forwarding
Specification (Version 1)" Work in Progress.
[Fuller93] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless
Inter-Domain Routing (CIDR): an Address Assignment and Aggregation
Strategy", RFC 1519, BARRNet, cisco Systems, MERIT, OARnet,
September 1993.
[Gillig94c] Gilligan, B., "IPng Transition (ngtrans)", Work in
Progress.
[Gross92} Gross, P., and P. Almquist, "IESG Deliberations on Routing
and Addressing", RFC 1380, ANS, Stanford University, November
1992.
[Gross94] Gross, P. "A Direction for IPng", RFC 1719, MCI, December
1994.
[Hinden92a] Hinden, R., "New Scheme for Internet Routing and
Addressing (ENCAPS)", Work in Progress.
[Hinden94b] Hinden, R., Deering, S., and P. Francis, "Simple Internet
Protocol Plus", Working Group Charter, April 1994.
Bradner & Mankin PAGE 49
RFC 1752 Recommendation for IPng January 1995
[Hinden92b] Hinden, R., and D. Crocker, "A Proposal for IP Address
Encapsulation (IPAE): A Compatible version of IP with Large
Addresses", Work in Progress.
[Huston94] Huston, G., and A. Bansal, draft charter for the
"Transition and Coexistence Including Testing (TACIT) Working
Group, June 1994.
[Huitema93] Huitema, C., "IAB Recommendations for an Intermediate
Strategy to Address the Issue of Scaling", RFC 1481, INRIA, July
1993.
[Huitema94] Huitema, C., "The H ratio for address assignment
efficiency", RFC 1715, INRIA, October 1994.
[IAB92] Internet Architecture Board, "IP Version 7", Work in
Progress.
[IAB94] Braden, R., Clark, D., Crocker, S., and C. Huitema, "Report
of IAB Workshop on Security in the Internet Architecture -
February 8-10, 1994", RFC 1636, USC/Informaiton Sciences
Institute, MIT Laboratory for Computer Science, Trusted
Information Systems, Inc., INRIA, IAB Chair, June 1994.
[Kasten92] Kastenholz, F, and C. Partridge, "IPv7 Technical
Criteria", Work in Progress.
[Kasten94] Partridge, C., and F. Kastenholz, "Technical Criteria for
Choosing IP: The Next Generation (IPng)", RFC 1726, BBN Systems
and Technologies, FTP Software, December 1994.
[Knopper94a] Knopper, M., and P. Ford, "TCP/UDP Over CLNP-Addressed
Networks (TUBA)", Working Group Charter, January 1994.
[Knopper94b] Knopper, M., and D. Piscitello, "Minutes of the BigTen
IPng Retreat, May 19 & 20 1994".
[Leiner93] Leiner, B., and Y. Rekhter, "The MultiProtocol Internet",
RFC 1560, USRA, IBM, December 1993.
[Mankin94] Mankin, A., and S. Bradner, message to big-internet, tuba,
sipp, catnip and ietf mailing lists, 7 July 1994.
[Mills84] Mills, D. "Exterior Gateway Protocol Formal Specification",
RFC 904, UDEL, April 1984.
[Mogul90] Mogul, J., and S. Deering, "Path MTU Discovery", RFC 1191,
DECWRL, Stanford University, November 1990.
Bradner & Mankin PAGE 50
RFC 1752 Recommendation for IPng January 1995
[Nat94] National Research Council, "Realizing the Information Future:
The Internet and Beyond", National Academy Press, 1994.
[Piscit94] Piscitello, D., "FTP Operation Over Big Address Records
(FOOBAR)", RFC 1639, Core Competence, June 1994.
[Provan91] Provan, D., "Transmitting IP Traffic over ARCNET
Networks", RFC 1051, Novell, February 1991.
[Postel94] Postel, J., Editor, "Internet Official Protocol
Standards", RFC 1720, USC/Information Sciences Institute, November
1994.
[Solens93a] Solensky, F., and T. Li, "Charter for the Address
Lifetime Expectations Working Group", FTP Software, Cisco Systems,
November 1993.
[Solens93b] Solensky, F., "Minutes of the Address Lifetime
Expectations BOF (ALE)", Houston IETF, November 1993,
(ietf/ale/ale-minutes-93nov.txt).
[Solens94] Solensky, F., "Minutes of the Address Lifetime
Expectations BOF (ALE)", Toronto IETF, July 1994, (ietf/ale/ale-
minutes-94jul.txt).
[Sukonnik94] Sukonnik, V., "Common Architecture for Next-Generation
IP (catnip), Working Group Charter, April 1994.
[Tsuchiya92] Tsuchiya, P., "The 'P' Internet Protocol", Work in
Progress.
[Ullmann93] Ullmann, R., "TP/IX: The Next Internet", RFC 1475,
Process Software Corporation, June 1993.
Bradner & Mankin PAGE 51
RFC 1752 Recommendation for IPng January 1995
Appendix G - Acknowledgments
Reaching this stage of the recommendation would not have been even
vaguely possible without the efforts of many people. In particular,
the work of IPng Directorate (listed in Appendix B), Frank Kastenholz
and Craig Partridge (the authors of the Criteria document) along with
Jon Crowcroft (who co-chaired the ngreq BOF) was critical. The work
and cooperation of the chairs, members and document authors of the
three IPng proposal working groups, the ALE working group and the
TACIT working group laid the groundwork upon which this
recommendation sits.
We would also like to thank the many people who took the time to
respond to RFC 1550 and who provided the broad understanding of the
many requirements of data networking that any proposal for an IPng
must address.
The members of the IESG, the IAB, and the always active participants
in the various mailing lists provided us with many insights into the
issues we faced.
Many other individuals gave us sometimes spirited but always useful
counsel during this process. They include (in no particular order)
Radia Perlman, Noel Chiappa, Peter Ford, Dave Crocker, Tony Li, Dave
Piscitello, Vint Cerf and Dan Lynch.
Thanks to David Williams and Cheryl Chapman who took on the
occasionally impossible task of ensuring that what is written here
resembles English to some degree.
To all of the many people mentioned above and those we have skipped
in our forgetfulness, thank you for making this task doable.
Bradner & Mankin PAGE 52
The Recommendation for the IP Next Generation Protocol
RFC TOTAL SIZE: 127784 bytes
PUBLICATION DATE: Friday, January 13th, 1995
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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