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
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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.
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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,
<https://www.rfc-editor.org/info/rfc1042>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
Appendix A. ChangeLog
The changes are listed in reverse chronological order, most recent
changes appearing at the top of the list.
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Author's Address
Alexandre Petrescu
CEA, LIST
CEA Saclay
Gif-sur-Yvette , Ile-de-France 91190
France
Phone: +33169089223
Email: Alexandre.Petrescu@cea.fr
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