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Distributed Mobility Management (DMM)                        J. Korhonen
Internet-Draft                                    Nokia Siemens Networks
Updates: 4861,3484 (if approved)                                B. Patil
Intended status: Standards Track                                   Nokia
Expires: September 12, 2012                                S. Gundavelli
                                                                   Cisco
                                                          March 11, 2012


               IPv6 Prefix Mobility Management Properties
              draft-korhonen-dmm-prefix-properties-01.txt

Abstract

   This specification defines an extension to the IPv6 Neighbor
   Discovery protocol and its Prefix Information Option.  The Prefix
   Information Option is extended with flag bits that describe the
   mobility management properties associated to the prefix.  This
   specification updates RFC4861 and also updates RFC3484 Source Address
   Selection algorithm.

Requirements Language

   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].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 12, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Background and Motivation . . . . . . . . . . . . . . . . . . . 3
   3.  Option Formats  . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Host Considerations . . . . . . . . . . . . . . . . . . . . . . 6
     4.1.  Internal Data Structures  . . . . . . . . . . . . . . . . . 6
     4.2.  Default Address Selection . . . . . . . . . . . . . . . . . 6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Appendix A.  Additions to the Socket Interface and the
                Protocol-Independent Nodename Translation  . . . . . . 8
     A.1.  Socket Interface  . . . . . . . . . . . . . . . . . . . . . 8
     A.2.  Protocol-Independent Nodename Translation . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9






















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1.  Introduction

   This specification defines an extension to the IPv6 Neighbor
   Discovery protocol and its Prefix Information Option (PIO) [RFC4861].
   The Prefix Information Option is extended with flag bits that
   describe the mobility management properties associated to the prefix,
   and at the same time defines corresponding source address selection
   hint flags to the IPv6 Socket API for Source Address Selection
   [RFC5014].

   The IPv6 Socket API for Source Address Selection [RFC5014] already
   covers Mobile IPv6 [RFC6275] and allows selecting between a home
   address (HoA) and a care-of address (CoA).  A mobile node (MN) with a
   client based mobility IP stack is supposed to know which prefixes are
   CoA(s) and/or HoA(s).  The extensions to [RFC4861] are minimal in a
   sense that they do not define new functionality to any existing
   mobility protocol but instead add an explicit indication of network
   based mobility knowledge into the IPv6 stateless address
   autoconfiguration (SLAAC).  This would allow for network based
   mobility solutions, such as Proxy Mobile IPv6 [RFC5213] or GTP
   [TS.29274] to explicitly indicate that their prefixes have mobility,
   and therefore, the MN IP stack can make an educated selection between
   prefixes that have mobility and those that do not.  There is also a
   potential need to extend both [RFC3493] and [RFC5014] in order to
   provide required hooks into socket APIs.

   The underlying assumption is that a MN has multiple prefixes to
   choose from.  Typically this means either the MN has multiple
   interfaces or an interface has been configured with multiple
   prefixes.  This specification does not make a distinction between
   these alternatives and does not either make any assumptions how the
   possible transfer of a prefix is done between interfaces in the case
   a network based mobility solution is used.


2.  Background and Motivation

   IP mobility and its centralized topological anchoring of IP addresses
   has known issues.  For instance, non-optimal routing is a classical
   example.  Another concerns include excessive tunneling, increased
   signaling due the maintenance of mobility related bindings,
   aggregation of traffic to centralized mobility anchor gateways and
   unnecessary IP mobility related state management for IP traffic that
   does not as such benefit from mobility.  In general, it is observed
   that most applications do not need IP level mobility, and work just
   fine with "temporary" IP addresses that come and go.  However, IP
   mobility still has its virtues making the applications unaware of
   mobility, and certain wireless mobile networking architecture make



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   extensive use of network based IP mobility.

   In order to overcome some of the above issues, use of local resources
   and topologically local addressing could be enhanced.  In many cases
   this would lead to use of multiple addresses of which some provide
   mobility and some do not.  However, an end host has to have means to
   distinguish between addresses that provide mobility, and those that
   are short lived and usable only within a limited topological area.
   This specification provides extensions to IPv6 address management and
   source address selection so that end hosts (and their applications)
   can select a proper address for their needs.

   [to be enhanced]


3.  Option Formats

   Neighbor Discovery messages include zero or more options, some of
   which may appear multiple times in the same message.  Options should
   be padded when necessary to ensure that they end on their natural 64-
   bit boundaries.  Figure 1 illustrates a Prefix Information Option
   [RFC4861] that is extended with flag bits describing the mobility
   properties of the prefix:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       3       |       4       | Prefix Length |L|A|   Rsvd1   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Valid Lifetime                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Preferred Lifetime                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | C |                       Reserved2                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                            Prefix                             +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1: Extended Prefix Information Option






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   'C' 2-bit flag field describing the mobility properties of the
       prefix.  The following properties are defined:

       00  No specific property associated to the prefix.  The prefix is
           treated according to RFC4861.

       01  The prefix may or may not provide network based mobility, and
           if mobility is provided that is only within a limited area.
           Therefore, the end host must be prepared that the prefix may
           become invalid abruptly before the valid or even the
           preferred lifetime expire.

       10  The prefix provides network based mobility and should remain
           unchanged the valid lifetime of the prefix.

       11  Reserved.  Treated as '00' by the receiver.

   A common use case is to define 'C' flags when the 'A'=1 i.e. when
   Stateless Address AutoConfiguration (SLAAC) is used.  However, it is
   possible to associate 'C' flags also to prefixes when 'A'=0.  In
   cases when there are multiple learned prefixes with 'C' flags set to
   a non-zero value that can also be aggregated, then the longest prefix
   takes precedence.

   If the prefix lifetime(s) is set to infinity that does not override
   the prefix mobility properties indicated in 'C' flags.  For instance,
   a prefix with an infinite lifetime but 'C' flags set to '01' indicate
   that the prefix is bound to change abruptly due a handover at some
   point of time.

   'C' flags also define the prefix preference for an IP stack that
   understands the extensions defined in this specification.  The IP
   stack SHOULD use the following preferences to supersede
   [I-D.ietf-6man-rfc3484bis] Source Address Selection Rule 8 when
   selecting a default source address among multiple choices and an
   application has not explicitly indicate what kind of source address
   it prefers:

   00  Medium (default) preference.

   01  High preference.

   10  Low preference.

   11  Reserved - MUST NOT be used.






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4.  Host Considerations

4.1.  Internal Data Structures

   The host internal data structures need to be extended with 'mobility
   property' flag information associated to the learned prefix and
   configured addresses.  How this is accomplished is host
   implementation specific.  It is also a host implementation issue how
   an application can learn or query mobility properties of an address
   or a prefix.  One possibility is to provide such information through
   the socket API extensions (see discussion in Appendix A).  Other
   possibilities include the use of e.g., ioctl() or NetLink [RFC3549]
   extensions.

4.2.  Default Address Selection

   The 'mobility property' flags are only used as a hint.  They do not
   affect the existing [I-D.ietf-6man-rfc3484bis] automatically.  A
   specific rule to host's policy table has to be inserted by an
   application or some daemon process.  Alternatively, an application
   can express its address mobility property preferences through the
   socket API extensions (see discussion in Appendix A), which means the
   socket library or middleware has to modify [I-D.ietf-6man-rfc3484bis]
   policy table or algorithm.


5.  Security Considerations

   Existing Prefix Information Option related security considerations
   apply as described in [RFC4861] and [RFC4191].  A malicious node on
   the shared link could include such 'mobility property' flags in a
   Prefix Information Option causing the host to learn wrong information
   regarding the prefix and thus make misguided selection of prefixes on
   the link.  Similarly a malicious middleman on the link could modify
   'mobility property' flags in a Prefix Information Option causing
   misguided selection of prefixes.  In order to avoid on-link attacks,
   SeND [RFC3971] can be used to reject Router Advertisements from
   potentially malicious nodes and guarantee integrity protection of the
   Router Advertisements.


6.  IANA Considerations

   Section 3 defines a new flag bits (2 bit 'C' flag) to the IPv6
   Neighbor Discovery protocol's Prefix Information Option [RFC4861].


7.  References



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7.1.  Normative References

   [I-D.ietf-6man-rfc3484bis]
              Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol version 6
              (IPv6)", draft-ietf-6man-rfc3484bis-01 (work in progress),
              March 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

7.2.  Informative References

   [RFC3493]  Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
              Stevens, "Basic Socket Interface Extensions for IPv6",
              RFC 3493, February 2003.

   [RFC3549]  Salim, J., Khosravi, H., Kleen, A., and A. Kuznetsov,
              "Linux Netlink as an IP Services Protocol", RFC 3549,
              July 2003.

   [RFC3971]  Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
              Neighbor Discovery (SEND)", RFC 3971, March 2005.

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

   [RFC5014]  Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
              Socket API for Source Address Selection", RFC 5014,
              September 2007.

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [TS.29274]
              3GPP, "3GPP Evolved Packet System (EPS);  Evolved General
              Packet Radio Service (GPRS)  Tunnelling Protocol for
              Control plane (GTPv2-C)", 3GPP TS 29.060 8.11.0,
              December 2010.





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Appendix A.  Additions to the Socket Interface and the Protocol-
             Independent Nodename Translation

   Following sections are for informational and discussion purposes
   only.

   This specification also describes non-normative extensions to both
   Socket Interface [RFC3493][RFC5014] and the Protocol-Independent
   Nodename Translation [RFC5014].  These socket APIs and DNS resolver
   APIs extension correspond to the Prefix Information option mobility
   properties flag bit settings.

A.1.  Socket Interface

   This specification extends the socket option IPV6_ADDR_PREFERENCES at
   the IPPROTO_IPV6 level.  The following new flags are defined to
   query, alter or set the default rule of source address selection
   rules [I-D.ietf-6man-rfc3484bis].  They are also defined as a result
   of including the <netinet/in.h> header:

   IPV6_PREFER_SRC_HNP     /* Prefer Home Network Prefix derived IPv6
                           address as source */

   IPV6_PREFER_SRC_HNP_TMP /* Prefer temoporary Home Network Prefix
                           derived IPv6 address as source */

A.2.  Protocol-Independent Nodename Translation

   the Default Address Selection [I-D.ietf-6man-rfc3484bis] document
   indicates possible implementation strategies for getaddrinfo().  The
   address selection hint flags for the getaddrinfo() specificed in this
   document extend the 'int ai_eflags' field in the struct addrinfo
   [RFC5014][RFC3493].

   The IPV6 source address preference values (IPV6_PREFER_SRC_HNP and
   IPV6_PREFER_SRC_HNP_TMP) defined for the IPV6_ADDR_PREFERENCES socket
   option are also defined as address selection preference flags in
   <netdb.h> header for the "ai_eflags" extended flag-set field of the
   addrinfo data structure.

   Similarly to [RFC5014], if contradictory flags, such as
   IPV6_PREFER_SRC_HOME and IPV6_PREFER_SRC_HNP*, are set in ai_eflags,
   the getaddrinfo() fails and returns the value EAI_BADEXTFLAGS.  This
   error value MUST be interpreted into a descriptive text string when
   passed to the gai_strerror() function [RFC3493].






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Authors' Addresses

   Jouni Korhonen
   Nokia Siemens Networks
   Linnoitustie 6
   FIN-02600 Espoo
   Finland

   Email: jouni.nospam@gmail.com


   Basavaraj Patil
   Nokia
   6021 Connection Drive
   Irving,  TX  75039
   USA

   Email: basavaraj.patil@nokia.com


   Sri Gundavelli
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Email: sgundave@cisco.com
























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