Unique Local IPv6 Unicast Addresses
RFC 4193

 
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Type RFC - Proposed Standard (October 2005; No errata)
Last updated 2013-03-02
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Network Working Group                                          R. Hinden
Request for Comments: 4193                                         Nokia
Category: Standards Track                                    B. Haberman
                                                                 JHU-APL
                                                            October 2005

                  Unique Local IPv6 Unicast Addresses

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document defines an IPv6 unicast address format that is globally
   unique and is intended for local communications, usually inside of a
   site.  These addresses are not expected to be routable on the global
   Internet.

Table of Contents

   1. Introduction ....................................................2
   2. Acknowledgements ................................................3
   3. Local IPv6 Unicast Addresses ....................................3
      3.1. Format .....................................................3
           3.1.1. Background ..........................................4
      3.2. Global ID ..................................................4
           3.2.1. Locally Assigned Global IDs .........................5
           3.2.2. Sample Code for Pseudo-Random Global ID Algorithm ...5
           3.2.3. Analysis of the Uniqueness of Global IDs ............6
      3.3. Scope Definition ...........................................6
   4. Operational Guidelines ..........................................7
      4.1. Routing ....................................................7
      4.2. Renumbering and Site Merging ...............................7
      4.3. Site Border Router and Firewall Packet Filtering ...........8
      4.4. DNS Issues .................................................8
      4.5. Application and Higher Level Protocol Issues ...............9
      4.6. Use of Local IPv6 Addresses for Local Communication ........9
      4.7. Use of Local IPv6 Addresses with VPNs .....................10

Hinden & Haberman           Standards Track                     [Page 1]
RFC 4193          Unique Local IPv6 Unicast Addresses       October 2005

   5. Global Routing Considerations ..................................11
      5.1. From the Standpoint of the Internet .......................11
      5.2. From the Standpoint of a Site .............................11
   6. Advantages and Disadvantages ...................................12
      6.1. Advantages ................................................12
      6.2. Disadvantages .............................................13
   7. Security Considerations ........................................13
   8. IANA Considerations ............................................13
   9. References .....................................................13
      9.1. Normative References ......................................13
      9.2. Informative References ....................................14

1.  Introduction

   This document defines an IPv6 unicast address format that is globally
   unique and is intended for local communications [IPV6].  These
   addresses are called Unique Local IPv6 Unicast Addresses and are
   abbreviated in this document as Local IPv6 addresses.  They are not
   expected to be routable on the global Internet.  They are routable
   inside of a more limited area such as a site.  They may also be
   routed between a limited set of sites.

   Local IPv6 unicast addresses have the following characteristics:

      - Globally unique prefix (with high probability of uniqueness).

      - Well-known prefix to allow for easy filtering at site
        boundaries.

      - Allow sites to be combined or privately interconnected without
        creating any address conflicts or requiring renumbering of
        interfaces that use these prefixes.

      - Internet Service Provider independent and can be used for
        communications inside of a site without having any permanent or
        intermittent Internet connectivity.

      - If accidentally leaked outside of a site via routing or DNS,
        there is no conflict with any other addresses.

      - In practice, applications may treat these addresses like global
        scoped addresses.

   This document defines the format of Local IPv6 addresses, how to
   allocate them, and usage considerations including routing, site
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