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On Demand Mobility Management

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8653.
Authors Alper E. Yegin , Kisuk Kweon , Jinsung Lee , Jungshin Park , Danny Moses
Last updated 2015-05-06
Replaces draft-yegin-dmm-ondemand-mobility
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IESG IESG state Became RFC 8653 (Informational)
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DMM Working Group                                               A. Yegin
Internet-Draft                                              Unaffiliated
Intended status: Standards Track                                K. Kweon
Expires: November 7, 2015                                         J. Lee
                                                                 J. Park
                                                                D. Moses
                                                             May 6, 2015

                     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
   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

   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 November 7, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

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   ( 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   4
   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.  Backwards Compatibility Considerations  . . . . . . . . . . .   7
     4.1.  Applications  . . . . . . . . . . . . . . . . . . . . . .   8
     4.2.  IP Stack in the Mobile Host . . . . . . . . . . . . . . .   8
     4.3.  Network Infrastructure  . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

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 the mobile host chaging its point of attachment within the IP
   network topology.  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 flows without any interruption.

   IP address reachability: The ability to maintain the same IP address
   for an extended period of time.  The IP address stays 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 is made available for serving incoming (e.g., TCP)

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   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 any mobile host
   attached to the compliant networks can enjoy these benefits.  Any
   application running on these mobile hosts is subjected to the same
   treatment with respect to the IP session continuity and IP address

   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 web server running on the mobile host).
   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 incurs some cost.  Mobile IP protocol 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 due to the introduction of a
   single point of failure [I-D.ietf-dmm-requirements].  Therefore, IP
   session continuity and IP address reachability should be be provided
   only when needed.

   Furthermore, when an application needs 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 change and never engage in mobility management.

   This document proposes a solution for the applications running on the
   mobile host to indicate whether they need IP session continuity or IP
   address reachability.  The network protocol stack on the mobile host,
   in conjunction with the network infrastructure, would provide the
   required type of IP service.  It is for the benefit of both the users

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   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

   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

   - Fixed IP Address

   This is what standard Mobile IP provides with a Home Address (HoA).
   The mobile host is configures 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.

   - Sustained IP 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.  The IP address may change after the
   termination of the IP session(s), therefore it does not exhibit

   A sustained IP address may be configured and maintained by using
   access network anchoring, corresponding network anchoring, or some
   other solution.

   - Nomadic IP 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 movement of the mobile

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   Applications running as servers at a published IP address require a
   Fixed IP Address.  Long-standing applications (e.g., an SSH session)
   may also require this type of address.  Those applications could use
   a Sustained IP 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 a Fixed IP Address.

   Applications with short-lived transient IP sessions can use Sustained
   IP Addresses.  For example: Web browsers.

   Applications with very short IP sessions, such as DNS client and
   instant messengers, can utilize Nomadic IP Addresses.  Even though
   they could very well use a Fixed of Sustained IP Addresses, the
   transmission latency would be minimized when a Nomadic IP Address is

3.2.  Granularity of Selection

   The IP address type selection is made on a per-socket granularity.
   Different parts of the same application may have different needs.
   For example, control-plane of an application may require a Fixed IP
   Address in order to stay reachable, whereas data-plane of the same
   application may be satisfied with a Sustained IP Address.

3.3.  On Demand Nature

   At any point in time, a mobile host may have a combination of IP
   addresses configured.  Zero or more Nomadic, zero or more Sustained,
   and zero or more Fixed IP addresses may be configured on the IP stack
   of the host.  The combination may be as a result of the host policy,
   application demand, or a mix of the two.

   When the application requires a specific type of IP address and such
   an IP address is not already configured on the host, then the IP
   stack shall attempt to configure one.  For example, a host may not
   always have a Fixed IP address available as such an address 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
   protocol is not available on the stack, or if its operation fails,
   then the IP stack shall fail the associated socket request.  In case
   of successful Mobile IP operation, a Fixed IP Address gets configured
   on the mobile host.  If another socket requests a Fixed 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 released or kept for future
   applications that may be launched and require a Fixed IP address.

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

   - 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 just 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_REQ_FIXED_IP /* Require a Fixed IP address as source */

   IPV6_REQ_SUSTAINED_IP /* Require a Sustained IP addr. as source */

   IPV6_REQ_NOMADIC_IP /* Require a Nomadic IP 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.
   TBD: Disallow this case?

   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.  Backwards Compatibility Considerations

   Backwards compatibility support is required by the following 3 types
   of entities:

   - The Applications on the mobile host

   - The IP stack in the mobile host

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   - The network infrastructure

4.1.  Applications

   Legacy applications that do not support the new flags will use the
   legacy API to the IP stack and will not enjoy On-Demand Mobility

   Applications using the new flags must be aware that they may be
   executed in environments that do not support On-Demand Mobility
   feature.  Such environments may include legacy IP stack in the mobile
   host, legacy network infrastructure, or both.  In either case, the
   API will return an error code and the invoking applications must
   respond with using legacy calls without On-Demand Mobility feature.

4.2.  IP Stack in the Mobile Host

   New IP stacks must continue to support all legacy operations.  If an
   application does not use On-Demand Mobility feature, the IP stack
   must respond in a legacy manner.

   If the network infrastructure supports On-Demand Mobility feature,
   the IP stack may still request specific types of source IP address
   transparently to legacy applications.  This may be useful for
   environments in which both legacy and new applications are executed.

   The definition of what type of addresses to request and how they are
   assigned to legacy applications are outside of the scope of this

4.3.  Network Infrastructure

   The network infrastructure may or may not support the On-Demand
   Mobility feature.  How the IP stack on the host and the network
   infrastructure behave in case of a compatibility issue is outside the
   scope of this API specification.

5.  Security Considerations

   The setting of certain IP address type on a given socket may be
   restricted to privileged applications.  For example, a Fixed 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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6.  IANA Considerations


7.  Acknowledgements

   We would like to thank Alexandru Petrescu, Dapeng Liu, John
   Kaippallimalil, Jouni Korhonen, Seil Jeon, Sri Gundavelli, and
   Xinpeng Wei for their valuable comments and suggestions on this work.

8.  References

8.1.  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.

8.2.  Informative References

              Chan, A., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for Distributed Mobility Management", draft-
              ietf-dmm-requirements-17 (work in progress), June 2014.

   [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.

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   [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.

Authors' Addresses

   Alper Yegin


   Kisuk Kweon
   South Korea


   Jinsung Lee
   South Korea


   Jungshin Park
   South Korea


   Danny Moses
   Intel Corporation
   Petah Tikva


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