On Demand Mobility Management

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Document Type Active Internet-Draft (individual)
Authors Alper Yegin  , Kisuk Kweon  , Jinsung Lee  , Jungshin Park 
Last updated 2013-07-03
Replaced by RFC 8653, RFC 8653
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DMM Working Group                                               A. Yegin
Internet-Draft                                                  K. Kweon
Intended status: Standards Track                                  J. Lee
Expires: January 04, 2014                                        J. Park
                                                           July 03, 2013

                     On Demand Mobility Management


   Applications differ with respect to whether they need IP session
   continuity and/or IP address reachability.  The network providing the
   same type of service to any mobile host and any application running
   on the host yields inefficiencies.  This document describes a
   solution for taking the application needs into account in selectively
   providing IP session continuity and IP address reachability on a per-
   socket basis.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 04, 2014.

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   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   3
   3.  Solution  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Types of IP Addresses . . . . . . . . . . . . . . . . . .   4
     3.2.  Granularity of Selection  . . . . . . . . . . . . . . . .   5
     3.3.  On Demand Nature  . . . . . . . . . . . . . . . . . . . .   5
     3.4.  Conveying the Selection . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   In the context of Mobile IP [RFC5563][RFC6275][RFC5213][RFC5944],
   following two attributes are defined for the IP service provided to
   the mobile hosts:

   IP session continuity: The ability to maintain an ongoing IP session
   by keeping the same local end-point IP address throughout the session
   despite moving among different IP networks.  The IP address of the
   host may change between two independent IP sessions, but that does
   not jeopardize the IP session continuity.  IP session continuity is
   essential for mobile hosts to maintain ongoing IP sessions without
   any interruption.

   IP address reachability: The ability to maintain the same IP address
   for an extended period of time.  The IP address shall stay the same
   across independent IP sessions, and even in the absence of any IP
   session.  The IP address may be published in a long-term registry
   (e.g., DNS), and it shall be available for serving incoming (e.g.,
   TCP) connections.  IP address reachability is essential for mobile
   hosts to use specific/published IP addresses.

   Mobile IP is designed to provide both IP session continuity and IP
   address reachability to mobile hosts.  Architectures utilizing these
   protocols (e.g., 3GPP, 3GPP2, WIMAX) ensure that every one of the
   mobile hosts attached to the compliant networks enjoy these benefits.
   Every application running on each one of those mobile hosts is

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   subjected to the same treatment with respect to the IP session
   continuity and IP address reachability.

   It should be noted that in reality not every application may need
   those benefits.  IP address reachability is required for applications
   running as servers (e.g., a camera mounted on a bus).  But, a typical
   client application (e.g., web browser) does not necessarily require
   IP address reachability.  Similarly, IP session continuity is not
   required for all types of applications either.  Applications
   performing brief communication (e.g., DNS client) can survive without
   having IP session continuity support.

   Achieving IP session continuity and IP address reachability by using
   Mobile IP incur some cost.  This solution forces the mobile host's IP
   traffic to traverse a centrally-located router (Home Agent, HA),
   which incurs additional transmission latency and use of additional
   network resources, adds to the network CAPEX and OPEX, and decreases
   the reliability of the network with the introduction of a single
   point of failure [I-D.ietf-dmm-requirements].  Therefore, IP session
   continuity and IP address reachability should be used selectively.

   Furthermore, even when an application needs IP session continuity, it
   may be able to satisfy that need by using a solution above the IP
   layer, such as MPTCP [RFC6824], SIP mobility [RFC3261], or an
   application-layer mobility solution.  Those higher-layer solutions
   are not subject to the same issues that arise with the use of Mobile
   IP since they can utilize the most direct data path between the end-
   points.  But, if Mobile IP is being applied to the mobile host, those
   higher-layer protocols are rendered useless because their operation
   is inhibited by the Mobile IP.  Since Mobile IP ensures the IP
   address of the mobile host remains fixed (despite the location and
   movement of the mobile host), the higher-layer protocols never detect
   the IP-layer movement and never engage in mobility management.

   This document proposes a solution where the applications running on
   the mobile host can indicate whether they need IP session continuity
   or IP address reachability.  The IP stack on the mobile host, in
   conjunction with the network, would provide the required type of IP
   service.  It is for the benefit of both the users and the network
   operators not to engage an extra level of service unless it is
   absolutely necessary.  So it is expected that applications and
   networks compliant with this specification would utilize this
   solution to use network resources more efficiently.

2.  Notational Conventions

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   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  Solution

3.1.  Types of IP Addresses

   Three types of IP addresses are defined with respect to the mobility

   - Home Network Anchored Address

   This is what standard Mobile IP provides with a Home Address (HoA).
   The mobile host is configured a HoA from a centrally-located Home
   Network.  Both IP session continuity and IP address reachability are
   provided to the mobile host with the help of a router in the Home
   Network (Home Agent, HA).  This router acts as an anchor for the IP
   address of the mobile host.

   - Access Network Anchored Address

   This type of IP address provides IP session continuity but not IP
   address reachability.  It is achieved by ensuring that the IP address
   used at the beginning of the session remains usable despite the
   movement of the mobile host.  But the IP address may change after the
   end of ongoing IP sessions, therefore it does not exhibit

   The IP address is allocated by a serving IP gateway.  When the mobile
   host moves to another network, the previously serving gateway becomes
   an anchor gateway and starts treating the IP address as a Home
   Address with the help of the received binding updates.  A tunnel is
   established between the anchor gateway and the current care-of
   address of the mobile host (whether configured on the host itself
   [RFC5944][RFC6275], or on the serving gateway [RFC5213][RFC5563]) for
   ensuring the session continuity using the same IP address.

   - Unanchored Address

   This type of IP address provides neither IP session continuity nor IP
   address reachability.  The IP address is obtained from the serving IP
   gateway and it is not maintained across gateway changes.  In other
   words, the IP address may be released and replaced by a new IP
   address when the IP gateway changes due to the mobile host's

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   Applications running as servers at a published IP address require
   Home Network Anchored Address.  Long-standing applications (e.g., an
   SSH session) may also require this type of address.  They could use
   Access Network Anchored Address, but that can produce sub-optimal
   results if the mobile host ends up far from the anchor gateway.
   Enterprise applications that connect to an enterprise network via
   virtual LAN require Home Network Anchored Address.

   Applications with short-lived transient IP sessions can use Access
   Network Anchored Address.  For example: Email client, web browser,
   calendar, app store client, etc.

   Applications with very short IP sessions, such as DNS client and
   instant messengers, can utilize Unanchored Address.  Even though they
   could very well use Home or Access Network Anchored Addresses, the
   transmission latency would be the minimum when an Unanchored Address
   is used.

3.2.  Granularity of Selection

   The IP address type selection is made at per-socket granularity.
   Different parts of the same application may have different needs.
   For example, control part of the application may require Home Network
   Anchored Address in order to stay reachable, whereas data part of the
   application may be satisfied with Access Network Anchored Address.

3.3.  On Demand Nature

   At any point in time, a mobile host may have any mixture of IP
   addresses configured.  Zero or more Unanchored, zero or more Access
   Network Anchored, and zero or more Home Network Anchored IP addresses
   may be available on the IP stack of the host.  The mixture may be as
   a result of the host policy, or as a result of the application

   If an IP address of the requested type is not available, then the IP
   stack shall attempt to configure one.  For example, a host may not
   always have a Home Network Anchored IP address available as this is
   rarely used.  In case an application requests one, then the IP stack
   shall make an attempt to configure one using Mobile IP.  If Mobile IP
   is not available to the host, or if its operation fails, then the IP
   stack shall fail the associated socket request.  In case of
   successful Mobile IP operation, a Home Network Anchored IP Address
   gets configured on the mobile host.  If another socket requests a
   Home Network Anchored IP address at a later time, then the same IP
   address may be served to that socket as well.  When the last socket
   using the requested IP address is closed, the IP address may be

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   The following are matters of policy, which may be dictated by the
   host itself, the network operator, or the compliant network

   - The initial set of IP addresses configured on the host at the boot

   - Permission to grant various types of IP addresses to a requesting

   - Determination of a default address type when an application does
   not make any explicit indication, whether it already supports the
   required API or it is a legacy application.

3.4.  Conveying the Selection

   The selection of the address type is conveyed from the applications
   to the IP stack in a way to influence the source address selection
   algorithm [RFC6724].

   The current source address selection algorithm operates on the
   available set of IP addresses when selecting an address.  According
   to the proposed solution, if the requested type IP address is not
   available at the time of the request, then the IP stack shall make an
   attempt to configure one such IP address.  The selected IP address
   shall be compliant with the requested IP address type, whether it is
   selected among available addresses or dynamically configured.  In the
   absence of a matching type (because it is not available and not
   configurable on demand), the source address selection algorithm shall
   return an empty set.

   A Socket API-based interface for enabling applications to influence
   the source address selection algorithm is described in [RFC5014].
   That specification defines IPV6_ADDR_PREFERENCES option at the
   IPPROTO_IPV6 level.  That option can be used with setsockopt() and
   getsockopt() calls to set and get address selection preferences.

   Furthermore, that RFC also specifies two flags that relate to IP
   mobility management: IPV6_PREFER_SRC_HOME and IPV6_PREFER_SRC_COA.
   These flags are used for influencing the source address selection to
   prefer either a Home Address or a Care-of Address.

   Unfortunately, these flags do not satisfy the aforementioned needs
   due to the following reasons, therefore new flags are proposed in
   this document:

   - Current flags indicate a "preference" whereas there is a need for
   indicating "requirement".  Source address selection algorithm does

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   not have to produce an IP address compliant with the "preference" ,
   but it has to produce an IP address compliant with the "requirement".

   - Current flags influence the selection made among available IP
   addresses.  The new flags force the IP stack to configure a compliant
   IP address if none is available at the time of the request.

   - The Home vs. Care-of Address distinction is not sufficient to
   capture the three different types of IP addresses described in
   Section 2.1.

   The following new flags are defined in this document and they shall
   be used with Socket API in compliance with the [RFC5014]:

   IPV6_REQUIRE_HOME_ANCHORED /* Require Home Anchored address as source

   IPV6_REQUIRE_ACCESS_ANCHORED /* Require Access Anchored address as
   source */

   IPV6_REQUIRE_UNANCHORED /* Require Unanchored address as source */

   More than one of these flags may be set on the same socket.  In that
   case, an IP address compliant with any one of them shall be selected.

   When any of these new flags is used, then the IPV6_PREFER_SRC_HOME
   and IPV6_PREFER_SRC_COA flags, if used, shall be ignored.

   These new flags are used with setsockopt()/getsockopt(),
   getaddrinfo(), and inet6_is_srcaddr() functions [RFC5014].  Similar
   with the setsockopt()/getsockopt() calls, getaddrinfo() call shall
   also trigger configuration of the required type IP address, if one is
   not already available.  When the new flags are used with
   getaddrinfo() and the triggered configuration fails, the
   getaddrinfo() call shall ignore that failure (i.e., not return an
   error code to indicate that failure).  Only the setsockopt() shall
   return an error when configuration of the requested type IP address

   Application of this solution to IPv4 is TBD.

4.  Security Considerations

   The setting of certain IP address type on a given socket may be
   restricted to privileged applications.  For example, a Home Anchored
   IP Address may be provided as a premium service and only certain
   applications may be allowed to use them.  Setting and enforcement of
   such privileges are outside the scope of this document.

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5.  IANA Considerations


6.  References

6.1.  Normative References

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

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

   [RFC6724]  Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol Version 6
              (IPv6)", RFC 6724, September 2012.

6.2.  Informative References

              Chan, A., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for Distributed Mobility Management", draft-
              ietf-dmm-requirements-05 (work in progress), June 2013.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

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

   [RFC5563]  Leung, K., Dommety, G., Yegani, P., and K. Chowdhury,
              "WiMAX Forum / 3GPP2 Proxy Mobile IPv4", RFC 5563,
              February 2010.

   [RFC5944]  Perkins, C., "IP Mobility Support for IPv4, Revised", RFC
              5944, November 2010.

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

   [RFC6824]  Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
              "TCP Extensions for Multipath Operation with Multiple
              Addresses", RFC 6824, January 2013.

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Authors' Addresses

   Alper Yegin

   Email: alper.yegin@partner.samsung.com

   Kisuk Kweon
   South Korea

   Email: kisuk.kweon@samsung.com

   Jinsung Lee
   South Korea

   Email: js81.lee@samsung.com

   Jungshin Park
   South Korea

   Email: shin02.park@samsung.com

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