Significance of IPv6 Interface Identifiers
RFC 7136
Document | Type |
RFC - Proposed Standard
(February 2014; No errata)
Updates RFC 4291
Was draft-ietf-6man-ug (6man WG)
|
|
---|---|---|---|
Authors | Brian Carpenter , Sheng Jiang | ||
Last updated | 2015-10-14 | ||
Replaces | draft-carpenter-6man-ug | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Ole Trøan | ||
Shepherd write-up | Show (last changed 2013-11-12) | ||
IESG | IESG state | RFC 7136 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Brian Haberman | ||
Send notices to | (None) | ||
IANA | IANA review state | IANA OK - Actions Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) B. Carpenter Request for Comments: 7136 Univ. of Auckland Updates: 4291 S. Jiang Category: Standards Track Huawei Technologies Co., Ltd ISSN: 2070-1721 February 2014 Significance of IPv6 Interface Identifiers Abstract The IPv6 addressing architecture includes a unicast interface identifier that is used in the creation of many IPv6 addresses. Interface identifiers are formed by a variety of methods. This document clarifies that the bits in an interface identifier have no meaning and that the entire identifier should be treated as an opaque value. In particular, RFC 4291 defines a method by which the Universal and Group bits of an IEEE link-layer address are mapped into an IPv6 unicast interface identifier. This document clarifies that those two bits are significant only in the process of deriving interface identifiers from an IEEE link-layer address, and it updates RFC 4291 accordingly. Status of This Memo This is an Internet Standards Track document. 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). Further information on Internet Standards is available in 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/rfc7136. Carpenter & Jiang Standards Track [Page 1] RFC 7136 IPv6 IID Significance February 2014 Copyright Notice Copyright (c) 2014 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 3. Usefulness of the U and G Bits . . . . . . . . . . . . . . . 5 4. The Role of Duplicate Address Detection . . . . . . . . . . . 6 5. Clarification of Specifications . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.2. Informative References . . . . . . . . . . . . . . . . . 8 1. Introduction IPv6 unicast addresses consist of a prefix followed by an Interface Identifier (IID). The IID is supposed to be unique on the links reached by routing to that prefix, giving an IPv6 address that is unique within the applicable scope (link local or global). According to the IPv6 addressing architecture [RFC4291], when a 64-bit IPv6 unicast IID is formed on the basis of an IEEE EUI-64 address, usually itself expanded from a 48-bit MAC address, a particular format must be used: For all unicast addresses, except those that start with the binary value 000, Interface IDs are required to be 64 bits long and to be constructed in Modified EUI-64 format. Thus, the specification assumes that the normal case is to transform an Ethernet-style address into an IID, but, in practice, there are various methods of forming such an IID. Carpenter & Jiang Standards Track [Page 2] RFC 7136 IPv6 IID Significance February 2014 The Modified EUI-64 format preserves the information provided by two particular bits in the MAC address: o The "u/l" bit in a MAC address [IEEE802] is set to 0 to indicate universal scope (implying uniqueness) or to 1 to indicate local scope (without implying uniqueness). In an IID formed from a MAC address, this bit is simply known as the "u" bit and its value is inverted, i.e., 1 for universal scope and 0 for local scope.Show full document text