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Versions: 00 01 02 03 04 05 06 07 RFC 5221

IPv6 Operations Working Group                               A. Matsumoto
Internet-Draft                                               T. Fujisaki
Intended status: Informational                                       NTT
Expires: November 16, 2007                                     R. Hiromi
                                                             K. Kanayama
                                                           Intec Netcore
                                                            May 15, 2007


             Requirements for address selection mechanisms
                draft-ietf-v6ops-addr-select-req-02.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   In a multi-prefix environment, nodes could have multiple addresses on
   one network interface.  RFC 3484 defines source and destination
   address-selection algorithm, which is commonly deployed in current
   popular OSs.  However, nodes could encounter some difficulties in
   network communication when they use default address selection rules



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   defined in RFC 3484.  Some mechanisms for solving address selection
   problems are proposed including the RFC 3484 policy table
   distribution and ICMP error-based mechanisms.  This document
   describes the requirements for these address selection mechanisms.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements of Address Selection . . . . . . . . . . . . . . . 3
     2.1.  Effectiveness . . . . . . . . . . . . . . . . . . . . . . . 3
     2.2.  Timing  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.3.  Dynamic Behavior Update . . . . . . . . . . . . . . . . . . 4
     2.4.  Node-Specific Behavior  . . . . . . . . . . . . . . . . . . 4
     2.5.  Application-Specific Behavior . . . . . . . . . . . . . . . 4
     2.6.  Multiple Interface  . . . . . . . . . . . . . . . . . . . . 4
     2.7.  Central Control . . . . . . . . . . . . . . . . . . . . . . 4
     2.8.  Next-hop Selection  . . . . . . . . . . . . . . . . . . . . 4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     5.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 5
   Intellectual Property and Copyright Statements  . . . . . . . . . . 7


























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1.  Introduction

   One physical network can have multiple logical networks.  In that
   case, an end-host has multiple IP addresses. ( e.g.  In the IPv4-IPv6
   dual-stack environment, in a site that uses both ULA [RFC4193] and
   global scope addresses or in a site connected to multiple upstream
   IPv6 networks) For such a host, RFC 3484 [RFC3484] defines default
   address-selection rules for the source and destination addresses.

   Today, the RFC 3484 mechanism is widely implemented in major OSs.
   However, we and others have found that in many sites the default
   address-selection rules are not appropriate for the network
   structure.  PS [I-D.ietf-v6ops-addr-select-ps] lists problematic
   cases that resulted from incorrect address selection.

   Though RFC 3484 made the address-selection behavior of a host
   configurable, typical users cannot make use of that because of the
   complexity of the mechanism and lack of knowledge about their network
   topologies.  Therefore, an address-selection autoconfiguration
   mechanism is necessary, especially for unmanaged hosts of typical
   users.

   This document contains requirements for address-selection mechanisms
   that enable hosts to perform appropriate address selection
   automatically.


2.  Requirements of Address Selection

   Address-selection mechanisms have to fulfill the following seven
   requirements.

2.1.  Effectiveness

   The mechanism can modify RFC 3484 default address-selection behavior
   at nodes.  As documented in PS [I-D.ietf-v6ops-addr-select-ps], the
   default rules defined in RFC 3484 do not work properly in some
   environment.  Therefore, the mechanism has to be able to modify
   address-selection behavior of a host.

2.2.  Timing

   Nodes can obtain address selection information when necessary.  If
   nodes need to have address-selection information before performing
   address selection, then the mechanism has to provide a way for nodes
   to obtain necessary information beforehand.  The mechanism should not
   degrade userbility.  The mechanism should not enforce long address-
   selection processing time upon users.



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2.3.  Dynamic Behavior Update

   Address-selection behavior of nodes can be dynamically updated.  When
   the network structure changes and address-selection behavior has to
   be changed accordingly, a network administrator can modify the
   address-selection behavior of nodes.

2.4.  Node-Specific Behavior

   The mechanism can support node-specific address-selection behavior.
   Even when multiple nodes are on the same subnet, the mechanism should
   be able to provide a method for the network administrator to make
   nodes behave differently.  For example, each node may have a
   different set of assigned prefixes.  In such a case, the appropriate
   address-selection behavior may be different.

2.5.  Application-Specific Behavior

   The mechanism can support application-specific address-selection
   behavior or combined use with an application-specific address-
   selection mechanism such as address-selection APIs.

2.6.  Multiple Interface

   The mechanism can support those nodes equipped with multiple
   interfaces.  The mechanism has to assume that nodes have multiple
   interfaces and makes address selection of those nodes work
   appropriately.

2.7.  Central Control

   The address selection behavior of nodes can be centrally controlled.
   A site administrator or a service provider can determine or have
   effect on address-selection behavior at their users' hosts.

2.8.  Next-hop Selection

   The mechanism can control next-hop-selection behavior at hosts or
   cooperate with other routing mechanisms, such as routing protocols
   and RFC 4191 [RFC4191].  If the address-selection mechanism is used
   with a routing mechanism, the two mechanisms has to be able to work
   synchronousely.


3.  Security Considerations

   Incorrect address-selection can lead to serious security problems,
   such as session hijack.  However, we should note that address-



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   selection is ultimately decided by nodes and their users.  There are
   no means to enforce a specific address-selection behavior upon every
   end-host from outside of the host.  Therefore, a network
   administrator has to take countermeasures for unexpected address
   selection.


4.  IANA Considerations

   This document has no actions for IANA.


5.  References

5.1.  Normative References

   [I-D.ietf-v6ops-addr-select-ps]
              Matsumoto, A., "Problem Statement of Default Address
              Selection in Multi-prefix Environment:  Operational Issues
              of RFC3484 Default Rules",
              draft-ietf-v6ops-addr-select-ps-01 (work in progress),
              April 2007.

   [RFC3484]  Draves, R., "Default Address Selection for Internet
              Protocol version 6 (IPv6)", RFC 3484, February 2003.

5.2.  Informative References

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, November 2005.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.


Authors' Addresses

   Arifumi Matsumoto
   NTT PF Lab
   Midori-Cho 3-9-11
   Musashino-shi, Tokyo  180-8585
   Japan

   Phone: +81 422 59 3334
   Email: arifumi@nttv6.net






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   Tomohiro Fujisaki
   NTT PF Lab
   Midori-Cho 3-9-11
   Musashino-shi, Tokyo  180-8585
   Japan

   Phone: +81 422 59 7351
   Email: fujisaki@syce.net


   Ruri Hiromi
   Intec Netcore, Inc.
   Shinsuna 1-3-3
   Koto-ku, Tokyo  136-0075
   Japan

   Phone: +81 3 5665 5069
   Email: hiromi@inetcore.com


   Ken-ichi Kanayama
   Intec Netcore, Inc.
   Shinsuna 1-3-3
   Koto-ku, Tokyo  136-0075
   Japan

   Phone: +81 3 5665 5069
   Email: kanayama@inetcore.com























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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

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