6MAN Working Group A. Petrescu Internet-Draft CEA, LIST Intended status: Standards Track September 21, 2018 Expires: March 25, 2019 The length of the IPv6 link-local prefix draft-petrescu-6man-ll-prefix-len-00 Abstract The length of the IPv6 link-local prefix is 64 decimal. 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 https://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 March 25, 2019. Copyright Notice Copyright (c) 2018 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 (https://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. Petrescu Expires March 25, 2019 [Page 1] Internet-Draft IPv6-LL-plen September 2018 Table of Contents 1. Statement . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Security Considerations . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 7. Normative References . . . . . . . . . . . . . . . . . . . . 3 Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 3 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Statement The length of the IPv6 link-local prefix is 64 decimal. The IPv6 link-local prefix is represented textually "fe80::/64". The illustration of the IPv6 link-local prefix is: | | 64 bits, the link-local prefix | 64 bits | +----------+-------------------------+----------------------------+ |1111111010000000000000...00000000000| interface ID | +----------+-------------------------+----------------------------+ Figure 1: The IPv6 link-local prefix 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. prefix: a contiguous string of bits valid for forwarding operations and for subnet formation. textual representation of a prefix: e.g. fe80::/64. n leading bits: the first n bits in a string of bits read from left to right in a writing system that is read left-to-right. E.g. the 10 leading bits of the fe80::/64 textual representation of the IPv6 link-local prefix are 1111111010. Petrescu Expires March 25, 2019 [Page 2] Internet-Draft IPv6-LL-plen September 2018 3. Security Considerations The clarification of the definition of the prefix length of the IPv6 link-local prefix at IANA is: call it 'leading bits' and not 'prefix', or state that the IPv6 prefix length of link-local addresses is 10 decimal. This clarification has beneficial impact in the algorithm implementation for calculation of the opaque and stable Interface Identifiers for IPv6 link-local addresses. It also positively impacts some implementations of IPv6 forwarding. 4. IANA Considerations IANA is requested to change the name of the column head in the table that depicts the "Internet Protocol Version 6 Address Space". The name should be "The n leading bits of an address" instead of "IPv6 Prefix". The desired effect of this change is that the IPv6 link-local prefix be "fe80::/64" and that the 10 leading bits of this prefix be 1111111010. A second effect is that the textual representation "fe80::/10" as an IPv6 link-local prefix should disappear from that IANA page, because it is wrong. 5. Contributors Listed from 6man WG discussion. 6. Acknowledgements Listed from 6man WG discussion. 7. Normative References [RFC1042] Postel, J. and J. Reynolds, "Standard for the transmission of IP datagrams over IEEE 802 networks", STD 43, RFC 1042, DOI 10.17487/RFC1042, February 1988, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Appendix A. ChangeLog The changes are listed in reverse chronological order, most recent changes appearing at the top of the list. Petrescu Expires March 25, 2019 [Page 3] Internet-Draft IPv6-LL-plen September 2018 Author's Address Alexandre Petrescu CEA, LIST CEA Saclay Gif-sur-Yvette , Ile-de-France 91190 France Phone: +33169089223 Email: Alexandre.Petrescu@cea.fr Petrescu Expires March 25, 2019 [Page 4]