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

some wordsmithing of fernando's text

Browse source
This commit is contained in:
Randy Bush 2017-05-08 20:59:41 +02:00
parent 3e399b1dbe
commit e8b242134c
1 changed files with 133 additions and 77 deletions
Download patch file Download diff file Expand all files Collapse all files

210
draft-nbourbaki-6man-classless-ipv6.txt
View file

@ -4,8 +4,8 @@
Network Working Group N. Bourbaki Network Working Group N. Bourbaki
Internet-Draft The Intertubes Internet-Draft The Intertubes
Intended status: Standards Track April 2017 Intended status: Standards Track May 8, 2017
Expires: October 3, 2017 Expires: November 9, 2017
IPv6 is Classless IPv6 is Classless
@ -14,10 +14,19 @@ Expires: October 3, 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, particularly Top-Level Aggregation (TLA) and Next-Level proposed, maybe the most notable being Top-Level Aggregation (TLA)
Aggregation (NLA) Identifiers. They have all proved to be mistakes. and Next-Level Aggregation (NLA) Identifiers. They have all proved
The last remnant is a rigid boundary at /64. This document removes to be mistakes. The last remnant is a rigid boundary at /64. This
that rigidity as far as routing is concerned. document removes that boundary as far as routing and addressing are
concerned.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
be interpreted as described in RFC 2119 [RFC2119] only when they
appear in all upper case. They may also appear in lower or mixed
case as English words, without normative meaning.
Status of This Memo Status of This Memo
@ -34,13 +43,21 @@ 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 October 3, 2017. This Internet-Draft will expire on November 9, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
Bourbaki Expires November 9, 2017 [Page 1]
Internet-Draft IPv6 is Classless May 2017
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
@ -51,13 +68,6 @@ Copyright Notice
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Bourbaki Expires October 3, 2017 [Page 1]
Internet-Draft IPv6 is Classless April 2017
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
@ -72,16 +82,17 @@ Table of Contents
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
10.1. Normative References . . . . . . . . . . . . . . . . . . 4 10.1. Normative References . . . . . . . . . . . . . . . . . . 4
10.2. Informative References . . . . . . . . . . . . . . . . . 5 10.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
Over the history of IPv6, various classful address models have been Over the history of IPv6, various classful address models have been
proposed, particularly Top-Level Aggregation (TLA) and Next-Level proposed, maybe the most notable being Top-Level Aggregation (TLA)
Aggregation(NLA) Identifiers. They have all proved to be mistakes. and Next-Level Aggregation (NLA) Identifiers; see, for example,
For example, TLA and NLA were obsoleted by [RFC3587]. The last [RFC2450]. They have all proved to be mistakes. For example, TLA
remnant is a rigid boundary at /64. This document removes that and NLA were obsoleted by [RFC3587]. The last remnant is a rigid
rigidity as far as routing is concerned. boundary at /64. This document removes that boundary as far as
routing and addressing are concerned.
2. Suggested Reading 2. Suggested Reading
@ -94,25 +105,23 @@ Table of Contents
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
Bourbaki Expires November 9, 2017 [Page 2]
Internet-Draft IPv6 is Classless May 2017
RFC4291 [I-D.hinden-6man-rfc4291bis], and the recent recommendations RFC4291 [I-D.hinden-6man-rfc4291bis], and the recent recommendations
for the generation of stable Interface Identifiers [RFC8064]. for the generation of stable Interface Identifiers [RFC8064].
An important recent development in IPv6 is that for host computers on An important recent IPv6 development was that, for host computers on
local area networks, the way in which interface identifiers are local area networks, the way in which interface identifiers were
formed is no longer bound to layer 2 addresses (MAC addresses) formed was no longer bound to layer 2 addresses (MACs) [RFC7217]
[RFC7217] [RFC8064]. We can therefore appreciate that their length, [RFC8064]. Therefore their length, previously fixed at 64 bits
previously fixed at 64 bits [RFC7136], is in fact a free parameter as [RFC7136], is in fact a free parameter as stated in [RFC4862].
stated in [RFC4862].
Bourbaki Expires October 3, 2017 [Page 2]
Internet-Draft IPv6 is Classless April 2017
3. Background 3. Background
@ -127,11 +136,15 @@ Internet-Draft IPv6 is Classless April 2017
4. A simple Statement 4. A simple Statement
To state it simply, IPv6 unicast routing is based on prefixes of any To state it simply, IPv6 unicast subnetting is based on prefixes of
valid length up to 128 except for links where an Internet Standard any valid length up to 128 except for links where an Internet
such as, for example, Stateless Address AutoConfiguration [RFC4862], Standard such as, for example, Stateless Address AutoConfiguration
or Using 127-Bit IPv6 Prefixes on Inter-Router Links [RFC6164] is in [RFC4862], or Using 127-Bit IPv6 Prefixes on Inter-Router Links
use. [RFC6164] is in use.
Nodes must always support rotuing on any valid length, even if SLAAC
or other standards are in use because routing could choose to
differentiate at a different granularity.
5. Recommendations 5. Recommendations
@ -139,53 +152,44 @@ Internet-Draft IPv6 is Classless April 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 needs to 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-bits was hard-coded, and SLAAC in order not to discover bugs where 64 was hard-coded, and to
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 None the less, there is no reason in theory why an IPv6 node should
not operate with different interface identfier lengths on different 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 length of prefix, with the value being
parameterised per interface. For instance, the Interface Identifier
length in the recommended (see [RFC8064]) algorithm for selecting
stable interface identifiers [RFC7217] is a parameter, rather than a
hardcoded value.
NOTE: should we comment on the fact that at least Linux and Windows
seem to assume that the default prefix is /64 in the management CLI?
Bourbaki Expires November 9, 2017 [Page 3]
Bourbaki Expires October 3, 2017 [Page 3]
Internet-Draft IPv6 is Classless April 2017 Internet-Draft IPv6 is Classless May 2017
fact allow for any prefix length, with the value being a parameter
per interface. For instance, the Interface Identifier length in the
recommended (see [RFC8064]) algorithm for selecting stable interface
identifiers [RFC7217] is a parameter, rather than a hardcoded value.
6. Security Considerations 6. Security Considerations
Assumming that nodes employ unpredictable interface identifiers Assumming 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
[RFC7707] [RFC7721]. However, that for some specific subnets (such [RFC7707] [RFC7721]. For some specific subnets, such as point to
as point to point links), this may be less of an issue. point links, this may be less of an issue.
On the other hand, we assume that a number of IPv6 implementations On the other hand, we assume that a number of IPv6 implementations
fail to enforce limits on the size of some of the data structures fail to enforce limits on the size of some of the data structures
they employ for communicating with neighboring nodes, such as the they employ for communicating with neighboring nodes, such as the
Neighbor Cache. In such cases, the use of smaller subnets Neighbor Cache. In such cases, the use of smaller subnets forces an
essentially enforces an operational limit on such data structures, operational limit on such data structures, thus helping mitigate some
thus helping mitigate some pathological behaviors (such as Neighbor pathological behaviors (such as Neighbor Cache Exhaustion attacks).
Cache Exhaustion attacks).
7. IANA Considerations 7. IANA Considerations
@ -194,8 +198,8 @@ Internet-Draft IPv6 is Classless April 2017
8. Authors 8. Authors
The original draft was by Randy Bush, who was immediately aided and The original draft was by Randy Bush, who was immediately aided and
abetted by Brian Carpenter, Chris Morrow, Fernando Gont, Job abetted by Brian Carpenter, Chris Morrow, Fernando Gont, Geoff
Snijders, [ your name here ]. Huston, Job Snijders, [ your name here ].
9. Acknowledgments 9. Acknowledgments
@ -205,9 +209,23 @@ Internet-Draft IPv6 is Classless April 2017
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2450] Hinden, R., "Proposed TLA and NLA Assignment Rules",
RFC 2450, December 1998.
[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 9, 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.
@ -217,15 +235,6 @@ Internet-Draft IPv6 is Classless April 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 October 3, 2017 [Page 4]
Internet-Draft IPv6 is Classless April 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,
@ -265,6 +274,14 @@ Internet-Draft IPv6 is Classless April 2017
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 9, 2017 [Page 5]
Internet-Draft IPv6 is Classless May 2017
Author's Address Author's Address
Nicolas Bourbaki Nicolas Bourbaki
@ -277,4 +294,43 @@ Author's Address
Bourbaki Expires October 3, 2017 [Page 5]
Bourbaki Expires November 9, 2017 [Page 6]