randy/draft-classless6
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

merge nick's changes

Browse source
This commit is contained in:
Randy Bush 2017-05-15 02:27:50 +09:00
parent 7ce39e3f1c
commit d080639bbe
1 changed files with 85 additions and 85 deletions
Download patch file Download diff file Expand all files Collapse all files

170
draft-nbourbaki-6man-classless-ipv6.txt
View file

@ -4,8 +4,9 @@
Network Working Group N. Bourbaki Network Working Group N. Bourbaki
Internet-Draft The Intertubes Internet-Draft The Intertubes
Intended status: Standards Track May 13, 2017 Updates: 4291 (if approved) May 15, 2017
Expires: November 14, 2017 Intended status: Standards Track
Expires: November 16, 2017
IPv6 is Classless IPv6 is Classless
@ -14,11 +15,10 @@ Expires: November 14, 2017
Abstract Abstract
Over the history of IPv6, various classful address models have been Over the history of IPv6, various classful address models have been
proposed, with the most notable being Top-Level Aggregation (TLA) and proposed, none of which has withstood the test of time. The last
Next-Level Aggregation (NLA) Identifiers. They have all proved to be remnant of IPv6 classful addressing is a rigid network interface
mistakes. The last remnant of classful addressing is a rigid network identifier boundary at /64. This document removes that boundary for
/ interface identifier boundary at /64. This document removes that routing and interface addressing.
boundary as far as routing and addressing are concerned.
Status of This Memo Status of This Memo
@ -35,7 +35,7 @@ Status of This Memo
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 14, 2017. This Internet-Draft will expire on November 16, 2017.
Copyright Notice Copyright Notice
@ -53,7 +53,7 @@ Copyright Notice
Bourbaki Expires November 14, 2017 [Page 1] Bourbaki Expires November 16, 2017 [Page 1]
Internet-Draft IPv6 is Classless May 2017 Internet-Draft IPv6 is Classless May 2017
@ -65,7 +65,7 @@ Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 2 2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 2
3. A simple Statement . . . . . . . . . . . . . . . . . . . . . 3 3. Identifier and Subnet Length Statements . . . . . . . . . . . 3
4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3 4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
@ -78,38 +78,38 @@ Table of Contents
1. Introduction 1. Introduction
Over the history of IPv6, various classful address models have been Over the history of the IPv6 protocol, several classful addressing
proposed, with the most notable being Top-Level Aggregation (TLA) and models have been proposed. The most notable example recommended Top-
Next-Level Aggregation (NLA) Identifiers; see, for example, Level Aggregation (TLA) and Next-Level Aggregation (NLA) Identifiers
[RFC2450]. They have all proved to be mistakes. For example, TLA [RFC2450], but was obsoleted by [RFC3587], leaving a single remnant
and NLA were obsoleted by [RFC3587]. The last remnant of classful of classful addressing in IPv6: a rigid network interface identifier
addressing is a rigid network / interface identifier boundary at /64. boundary at /64. This document removes that boundary for interface
This document removes that boundary as far as routing and addressing addressing.
are concerned.
Some confusion has been caused by the IP Version 6 Addressing Recent proposed changes to the IP Version 6 Addressing Architecture
Architecture, [RFC4291], and the proposed changes in specification [RFC4291] have caused controversy. While link prefixes
[I-D.ietf-6man-rfc4291bis] with respect to the minimum subnet size. of varied lengths, e.g. /127, /126, /124, /120, ... /64 have been
successfully deployed for many years, glaring mismatches between a
formal specification and long-standing field deployment practices are
never wise, not least because of the strong risk of mis-
implementation, which can easily result in serious operational
problems.
Meanwhile, link prefixes of varied lengths, /127, /126, /124, /120, This document also clarifies that IPv6 routing subnets may be of any
... /64 have been successfully deployed for many years. Having the length up to 128.
formal specification be unclear risks potential mis-implementation by
the naive, which could result in operational disasters.
2. Suggested Reading 2. Suggested Reading
It is assumed that the reader understands the history of classful It is assumed that the reader understands the history of classful
addressing in IPv4 and why it was abolished [RFC4632]. Of course, addressing in IPv4 and why it was abolished [RFC4632]. Of course,
the acute need to conserve address space that forced the adoption of the acute need to conserve address space that forced the adoption of
classless addressing for IPv4 does not apply to IPv6; but the classless addressing for IPv4 does not apply to IPv6, but the
arguments for operational flexibility in address allocation remain arguments for operational flexibility in address assignment remain
compelling. compelling.
Bourbaki Expires November 16, 2017 [Page 2]
Bourbaki Expires November 14, 2017 [Page 2]
Internet-Draft IPv6 is Classless May 2017 Internet-Draft IPv6 is Classless May 2017
@ -117,29 +117,37 @@ Internet-Draft IPv6 is Classless May 2017
It is also assumed that the reader understands IPv6 [RFC2460], the IP It is also assumed that the reader understands IPv6 [RFC2460], the IP
Version 6 Addressing Architecture [RFC4291], the proposed changes to Version 6 Addressing Architecture [RFC4291], the proposed changes to
RFC4291 [I-D.ietf-6man-rfc4291bis] and RFC2464 RFC4291 [I-D.ietf-6man-rfc4291bis] and RFC2464
[I-D.hinden-6man-rfc2464bis], and the recent recommendations for the [I-D.hinden-6man-rfc2464bis], and the IETF recommendation for the
generation of stable Interface Identifiers [RFC8064]. generation of stable Interface Identifiers [RFC8064].
An important recent IPv6 development was that, for host computers on For host computers on local area networks, generation of interface
local area networks, the way in which interface identifiers were identifiers is no longer necessarily bound to layer 2 addresses
formed was no longer bound to layer 2 addresses (MACs) [RFC7217] (MACs) [RFC7217] [RFC8064]. Therefore their length, previously fixed
[RFC8064]. Therefore their length, previously fixed at 64 bits at 64 bits [RFC7136], is in fact a variably-sized parameter as
[RFC7136], is in fact a variably-sized parameter as stated in explicitly acknowledged in Section 5.5.3(d) of [RFC4862] which
[RFC4862]. states:
3. A simple Statement Note that a future revision of the address architecture [RFC4291]
and a future link-type-specific document, which will still be
consistent with each other, could potentially allow for an
interface identifier of length other than the value defined in the
current documents. Thus, an implementation should not assume a
particular constant. Rather, it should expect any lengths of
interface identifiers.
To state it simply, IPv6 unicast subnetting is based on prefixes of 3. Identifier and Subnet Length Statements
any valid length up to 128 except for links where an Internet
Standard that has nothing to do with routing may impose a particular
length. Examples are Stateless Address AutoConfiguration (SLAAC)
[RFC4862], or Using 127-Bit IPv6 Prefixes on Inter-Router Links
[RFC6164].
Nodes must always support routing on any valid network prefix length, IPv6 unicast interfaces may use any subnet length up to 128 except
even if SLAAC or other standards are in use, because routing could for situations where an Internet Standard document may impose a
choose to differentiate at a different granularity than is used by particular length, for example Stateless Address Autoconfiguration
any such automated link local address configuration tools. (SLAAC) [RFC4862], or Using 127-Bit IPv6 Prefixes on Inter-Router
Links [RFC6164].
Additionally, this document clarifies that a node or router MUST
support routing of any valid network prefix length, even if SLAAC or
other standards are in use, because routing could choose to
differentiate at a different granularity than is used by any such
automated link local address configuration tools.
4. Recommendations 4. Recommendations
@ -147,32 +155,32 @@ Internet-Draft IPv6 is Classless May 2017
other considerations, a /64 is recommended [RFC7136]. other considerations, a /64 is recommended [RFC7136].
The length of the Interface Identifier in Stateless Address The length of the Interface Identifier in Stateless Address
AutoConfiguration [RFC4862] is a parameter; its length SHOULD be Autoconfiguration [RFC4862] is a parameter; its length SHOULD be
sufficient for effective randomization for privacy reasons. For sufficient for effective randomization for privacy reasons. For
example, a /48 might be sufficient. But operationally we recommend, example, a /48 might be sufficient. But operationally we recommend,
barring strong considerations to the contrary, using 64-bits for barring strong considerations to the contrary, using 64-bits for
SLAAC in order not to discover bugs where 64 was hard-coded, and to SLAAC in order not to discover bugs where 64 was hard-coded, and to
favor portability of devices and operating systems. favor portability of devices and operating systems.
None the less, there is no reason in theory why an IPv6 node should
not operate with different interface identfier lengths on different
Bourbaki Expires November 16, 2017 [Page 3]
Internet-Draft IPv6 is Classless May 2017
Nonetheless, there is no reason in theory why an IPv6 node should not
operate with different interface identfier lengths on different
physical interfaces. Thus, a correct implementation of SLAAC must in physical interfaces. Thus, a correct implementation of SLAAC must in
fact allow for any prefix length, with the value being a parameter fact allow for any prefix length, with the value being a parameter
per interface. For instance, the Interface Identifier length in the per interface. For instance, the Interface Identifier length in the
recommended (see [RFC8064]) algorithm for selecting stable interface recommended (see [RFC8064]) algorithm for selecting stable interface
identifiers [RFC7217] is a parameter, rather than a hardcoded value. identifiers [RFC7217] is a parameter, rather than a hardcoded value.
Bourbaki Expires November 14, 2017 [Page 3]
Internet-Draft IPv6 is Classless May 2017
5. Security Considerations 5. Security Considerations
Assumming that nodes employ unpredictable interface identifiers Assuming that nodes employ unpredictable interface identifiers
[RFC7721], the subnet size may have an impact on some security and [RFC7721], the subnet size may have an impact on some security and
privacy properties of a network. Namely, the smaller the subnet privacy properties of a network. Namely, the smaller the subnet
size, the more feasible it becomes to perform IPv6 address scans size, the more feasible it becomes to perform IPv6 address scans
@ -210,6 +218,14 @@ Internet-Draft IPv6 is Classless May 2017
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998. (IPv6) Specification", RFC 2460, December 1998.
Bourbaki Expires November 16, 2017 [Page 4]
Internet-Draft IPv6 is Classless May 2017
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006. Architecture", RFC 4291, February 2006.
@ -219,13 +235,6 @@ Internet-Draft IPv6 is Classless May 2017
DOI 10.17487/RFC7217, April 2014, DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>. <http://www.rfc-editor.org/info/rfc7217>.
Bourbaki Expires November 14, 2017 [Page 4]
Internet-Draft IPv6 is Classless May 2017
[RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu,
"Recommendation on Stable IPv6 Interface Identifiers", "Recommendation on Stable IPv6 Interface Identifiers",
RFC 8064, DOI 10.17487/RFC8064, February 2017, RFC 8064, DOI 10.17487/RFC8064, February 2017,
@ -265,23 +274,19 @@ Internet-Draft IPv6 is Classless May 2017
Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016, Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016,
<http://www.rfc-editor.org/info/rfc7707>. <http://www.rfc-editor.org/info/rfc7707>.
Bourbaki Expires November 16, 2017 [Page 5]
Internet-Draft IPv6 is Classless May 2017
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms", Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016, RFC 7721, DOI 10.17487/RFC7721, March 2016,
<http://www.rfc-editor.org/info/rfc7721>. <http://www.rfc-editor.org/info/rfc7721>.
Bourbaki Expires November 14, 2017 [Page 5]
Internet-Draft IPv6 is Classless May 2017
Author's Address Author's Address
Nicolas Bourbaki Nicolas Bourbaki
@ -328,9 +333,4 @@ Author's Address
Bourbaki Expires November 16, 2017 [Page 6]
Bourbaki Expires November 14, 2017 [Page 6]