The length of the IPv6 link-local prefix
draft-petrescu-6man-ll-prefix-len-02

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6MAN Working Group                                           A. Petrescu
Internet-Draft                                                 CEA, LIST
Intended status: Standards Track                      September 24, 2018
Expires: March 28, 2019

                The length of the IPv6 link-local prefix
                  draft-petrescu-6man-ll-prefix-len-02

Abstract

   The length of the IPv6 link-local prefix is 64 decimal.

Status of This Memo

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   This Internet-Draft will expire on March 28, 2019.

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Table of Contents

   1.  Statement . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Context . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  ChangeLog  . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

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.  Context

   The RFC "IPv6 Address Archi" illustrates the format of the link-local
   addresses.  From the illustration it MAY be understood that the
   length of the link-local prefix is 10 bits of value 1111111010 and 54
   0 bits.

   IANA lists the "IPv6 prefix", and "Address Block", to be "fe80::/10"
   on its website.  It is possible that in the future the IETF could
   decide to use the bits 11-53.

   The RFC 2464 "IPv6-over-Ethernet" states that the prefix for link-
   local addresses is "fe80::/64".

   RFC 6874, "Representing IPv6 Zone Identifiers in Address Literals and
   Uniform Resource Identifiers" specifies the link-local addresses to
   be under prefix "fe80::/10".

   Several knowledgeable interpretations state that, generally speaking,
   the prefix length of link-local addresses is 10, but it is 64 in the
   particular case of Stateless Address-Autoconfiguration (SLAAC).  In
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