diff --git a/draft-nbourbaki-6man-classless-ipv6.txt b/draft-nbourbaki-6man-classless-ipv6.txt new file mode 100644 index 0000000..9cc9626 --- /dev/null +++ b/draft-nbourbaki-6man-classless-ipv6.txt @@ -0,0 +1,280 @@ + + + + +Network Working Group N. Bourbaki +Internet-Draft The Intertubes +Intended status: Standards Track April 17, 2017 +Expires: October 19, 2017 + + + IPv6 is Classless + draft-bourbaki-6man-classless-ipv6-00 + +Abstract + + Over the history of IPv6, various classful address models have been + proposed, particularly Top-Level Aggregation (TLA) and Next-Level + Aggregation(NLA) Identifiers. They have all proved to be mistakes. + The last remnant is a rigid boundary at /64. This document removes + that rigidity as far as routing is concerned. + +Status of This Memo + + This Internet-Draft is submitted in full conformance with the + provisions of BCP 78 and BCP 79. + + Internet-Drafts are working documents of the Internet Engineering + Task Force (IETF). Note that other groups may also distribute + working documents as Internet-Drafts. The list of current Internet- + Drafts is at http://datatracker.ietf.org/drafts/current/. + + Internet-Drafts are draft documents valid for a maximum of six months + and may be updated, replaced, or obsoleted by other documents at any + time. It is inappropriate to use Internet-Drafts as reference + material or to cite them other than as "work in progress." + + This Internet-Draft will expire on October 19, 2017. + +Copyright Notice + + Copyright (c) 2017 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (http://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Simplified BSD License text as described in Section 4.e of + the Trust Legal Provisions and are provided without warranty as + described in the Simplified BSD License. + + + +Bourbaki Expires October 19, 2017 [Page 1] + +Internet-Draft IPv6 is Classless April 2017 + + +Table of Contents + + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 2 + 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 4. A simple Statement . . . . . . . . . . . . . . . . . . . . . 3 + 5. Notes and Recommendations . . . . . . . . . . . . . . . . . . 3 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 3 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 + 8. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 + 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 10.1. Normative References . . . . . . . . . . . . . . . . . . 4 + 10.2. Informative References . . . . . . . . . . . . . . . . . 4 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 + +1. Introduction + + Over the history of IPv6, various classful address models have been + proposed, particularly Top-Level Aggregation (TLA) and Next-Level + Aggregation(NLA) Identifiers. They have all proved to be mistakes. + For example, TLA and NLA were obsoleted by [RFC3587]. The last + remnant is a rigid boundary at /64. This document removes that + rigidity as far as routing is concerned. + +2. Suggested Reading + + It is assumed that the reader understands the history of classful + addressing in IPv4 and why it was abolished [RFC4632]. Of course, + the acute need to conserve address space that forced the adoption of + classless addressing for IPv4 does not apply to IPv6; but the + arguments for operational flexibility in address allocation remain + compelling. + + It is also assumed that the reader understands IPv6, [RFC2460], IP + Version 6 Addressing Architecture, see [RFC4291], and the proposed + changes to [RFC4291], see [I-D.hinden-6man-rfc2464bis]. + + NOTE: do we mean 4291bis (currently moribund) or 2464bis? + + An important recent development in IPv6 is that for host computers on + local area networks, the way in which interface identifiers are + formed is no longer bound to layer 2 addresses (MAC addresses) + [RFC7217]. We can therefore appreciate that their length, previously + fixed at 64 bits [RFC7136], is in fact a free parameter as stated in + [RFC4862]. + + + + + +Bourbaki Expires October 19, 2017 [Page 2] + +Internet-Draft IPv6 is Classless April 2017 + + +3. Background + + Some confusion has been caused by the IP Version 6 Addressing + Architecture, [RFC4291], and the proposed changes in + [I-D.hinden-6man-rfc2464bis] with respect to allowed maximum prefix + lengths and the minimum host part (sometimes known as interface + identifier) on a link. + + Meanwhile, link prefixes of varied lengths, /127, /126, /124, /120, + ... /64 have been successfully deployed for many years. Having the + formal specification be unclear risks potential mis-implementation by + the naive, which could result in operational disasters. + +4. A simple Statement + + To state it simply, IPv6 unicast routing is based on prefixes of any + valid length up to 128 except for links where an Internet Standard + such as, for example, Stateless Address AutoConfiguration [RFC4862], + or Using 127-Bit IPv6 Prefixes on Inter-Router Links [RFC6164] is in + use. + +5. Notes and Recommendations + + For historical reasons, when a prefix is needed on a link, barring + other considerations, a /64 is traditional [RFC7136]. + + The length of the prefix identifier in Stateless Address + AutoConfiguration, [RFC4862] is a parameter; its length needs to be + sufficient for effective randomization for privacy reasons. For + example, a /48 might be sufficient. But operationally we recommend, + barring strong considerations to the contrary, using 64-bits for + SLAAC in order not to discover bugs where 64-bits was hard-coded, and + to 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 + physical interfaces. Thus a correct implementation of SLAAC must in + fact allow for any length of prefix, with the value being + parameterised per interface. + + 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? + +6. Security Considerations + + This document has no known security impact, assuming that user + devices use an unpredictable interface identifier [RFC7721] for + privacy. + + + +Bourbaki Expires October 19, 2017 [Page 3] + +Internet-Draft IPv6 is Classless April 2017 + + +7. IANA Considerations + + This document has no IANA Considerations. + +8. Authors + + The original draft was by Randy Bush, who was immediately aided and + abetted by Brian Carpenter, Job Snijders, [ your name here ]. + +9. Acknowledgments + + The authors wish to thank . + +10. References + +10.1. Normative References + + [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 + (IPv6) Specification", RFC 2460, December 1998. + + [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing + Architecture", RFC 4291, February 2006. + +10.2. Informative References + + [I-D.hinden-6man-rfc2464bis] + Crawford, M. and R. Hinden, "Transmission of IPv6 Packets + over Ethernet Networks", draft-hinden-6man-rfc2464bis-02 + (work in progress), March 2017. + + [RFC3587] Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global + Unicast Address Format", RFC 3587, August 2003. + + [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing + (CIDR): The Internet Address Assignment and Aggregation + Plan", BCP 122, RFC 4632, August 2006. + + [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless + Address Autoconfiguration", RFC 4862, September 2007. + + [RFC6164] Kohno, M., Nitzan, B., Bush, R., Matsuzaki, Y., Colitti, + L., and T. Narten, "Using 127-Bit IPv6 Prefixes on Inter- + Router Links", RFC 6164, April 2011. + + [RFC7136] Carpenter, B. and S. Jiang, "Significance of IPv6 + Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136, + February 2014, . + + + + +Bourbaki Expires October 19, 2017 [Page 4] + +Internet-Draft IPv6 is Classless April 2017 + + + [RFC7217] Gont, F., "A Method for Generating Semantically Opaque + Interface Identifiers with IPv6 Stateless Address + Autoconfiguration (SLAAC)", RFC 7217, + DOI 10.17487/RFC7217, April 2014, + . + + [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy + Considerations for IPv6 Address Generation Mechanisms", + RFC 7721, DOI 10.17487/RFC7721, March 2016, + . + +Author's Address + + Nicolas Bourbaki + The Intertubes + 42 Rue du Jour + Sophia-Antipolis ::1 + FR + + Email: bourbaki@bogus.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Bourbaki Expires October 19, 2017 [Page 5]