RFC 3484 (rfc3484) - Page 2 of 24


Default Address Selection for Internet Protocol version 6 (IPv6)



Alternative Format: Original Text Document



RFC 3484           Default Address Selection for IPv6      February 2003


Table of Contents

   1.    Introduction................................................2
         1.1.  Conventions Used in This Document.....................4
   2.    Context in Which the Algorithms Operate.....................4
         2.1.  Policy Table..........................................5
         2.2.  Common Prefix Length..................................6
   3.    Address Properties..........................................6
         3.1.  Scope Comparisons.....................................7
         3.2.  IPv4 Addresses and IPv4-Mapped Addresses..............7
         3.3.  Other IPv6 Addresses with Embedded IPv4 Addresses.....8
         3.4.  IPv6 Loopback Address and Other Format Prefixes.......8
         3.5.  Mobility Addresses....................................8
   4.    Candidate Source Addresses..................................8
   5.    Source Address Selection...................................10
   6.    Destination Address Selection..............................12
   7.    Interactions with Routing..................................14
   8.    Implementation Considerations..............................15
   9.    Security Considerations....................................15
   10.   Examples...................................................16
         10.1. Default Source Address Selection.....................16
         10.2. Default Destination Address Selection................17
         10.3. Configuring Preference for IPv6 or IPv4..............18
         10.4. Configuring Preference for Scoped Addresses..........19
         10.5. Configuring a Multi-Homed Site.......................19
   Normative References.............................................21
   Informative References...........................................22
   Acknowledgments..................................................23
   Author's Address.................................................23
   Full Copyright Statement.........................................24

1. Introduction

   The IPv6 addressing architecture [1] allows multiple unicast
   addresses to be assigned to interfaces.  These addresses may have
   different reachability scopes (link-local, site-local, or global).
   These addresses may also be "preferred" or "deprecated" [2].  Privacy
   considerations have introduced the concepts of "public addresses" and
   "temporary addresses" [3].  The mobility architecture introduces
   "home addresses" and "care-of addresses" [8].  In addition, multi-
   homing situations will result in more addresses per node.  For
   example, a node may have multiple interfaces, some of them tunnels or
   virtual interfaces, or a site may have multiple ISP attachments with
   a global prefix per ISP.

   The end result is that IPv6 implementations will very often be faced
   with multiple possible source and destination addresses when
   initiating communication.  It is desirable to have default



Draves                      Standards Track