Analysis of the 64-bit Boundary in IPv6 Addressing
RFC 7421
| Document | Type |
RFC - Informational
(January 2015; Errata)
Was draft-ietf-6man-why64 (6man WG)
|
|
|---|---|---|---|
| Last updated | 2019-04-23 | ||
| Replaces | draft-carpenter-6man-why64 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Bob Hinden | ||
| Shepherd write-up | Show (last changed 2014-09-10) | ||
| IESG | IESG state | RFC 7421 (Informational) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Brian Haberman | ||
| Send notices to | (None) | ||
| IANA | IANA review state | IANA OK - No Actions Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) B. Carpenter, Ed.
Request for Comments: 7421 Univ. of Auckland
Category: Informational T. Chown
ISSN: 2070-1721 Univ. of Southampton
F. Gont
SI6 Networks / UTN-FRH
S. Jiang
Huawei Technologies Co., Ltd
A. Petrescu
CEA, LIST
A. Yourtchenko
Cisco
January 2015
Analysis of the 64-bit Boundary in IPv6 Addressing
Abstract
The IPv6 unicast addressing format includes a separation between the
prefix used to route packets to a subnet and the interface identifier
used to specify a given interface connected to that subnet.
Currently, the interface identifier is defined as 64 bits long for
almost every case, leaving 64 bits for the subnet prefix. This
document describes the advantages of this fixed boundary and analyzes
the issues that would be involved in treating it as a variable
boundary.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7421.
Carpenter, et al. Informational [Page 1]
RFC 7421 Why 64 January 2015
Copyright Notice
Copyright (c) 2015 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Advantages of a Fixed Identifier Length . . . . . . . . . . . 4
3. Arguments for Shorter Identifier Lengths . . . . . . . . . . 5
3.1. Insufficient Address Space Delegated . . . . . . . . . . 5
3.2. Hierarchical Addressing . . . . . . . . . . . . . . . . . 6
3.3. Audit Requirement . . . . . . . . . . . . . . . . . . . . 7
3.4. Concerns over ND Cache Exhaustion . . . . . . . . . . . . 7
4. Effects of Varying the Interface Identifier Length . . . . . 8
4.1. Interaction with IPv6 Specifications . . . . . . . . . . 8
4.2. Possible Failure Modes . . . . . . . . . . . . . . . . . 10
4.3. Experimental Observations . . . . . . . . . . . . . . . . 12
4.3.1. Survey of the processing of Neighbor Discovery
Options with Prefixes Other than /64 . . . . . . . . 12
4.3.2. Other Observations . . . . . . . . . . . . . . . . . 14
4.4. Implementation and Deployment Issues . . . . . . . . . . 14
4.5. Privacy Issues . . . . . . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Normative References . . . . . . . . . . . . . . . . . . 17
6.2. Informative References . . . . . . . . . . . . . . . . . 21
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
Carpenter, et al. Informational [Page 2]
RFC 7421 Why 64 January 2015
1. Introduction
Rather than simply overcoming the IPv4 address shortage by doubling
the address size to 64 bits, IPv6 addresses were originally chosen to
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