Network Working Group                                      H. Chan (Ed.)
Internet-Draft                                       Huawei Technologies
Intended status: Informational                                    D. Liu
Expires: December 7, 2014                                   China Mobile
                                                                P. Seite
                                                               H. Yokota
                                                                KDDI Lab
                                                             J. Korhonen
                                                 Broadcom Communications
                                                            June 5, 2014

            Requirements for Distributed Mobility Management


   This document defines the requirements for Distributed Mobility
   Management (DMM) at the network layer.  The hierarchical structure in
   traditional wireless networks has led primarily to centrally deployed
   mobility anchors.  As some wireless networks are evolving away from
   the hierarchical structure, it can be useful to have a distributed
   model for mobility management in which traffic does not need to
   traverse centrally deployed mobility anchors far from the optimal
   route.  The motivation and the problems addressed by each requirement
   are also described.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   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

   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."

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   This Internet-Draft will expire on December 7, 2014.

Copyright Notice

   Copyright (c) 2014 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
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions used in this document  . . . . . . . . . . . . . .  5
     2.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Centralized versus distributed mobility management . . . . . .  7
     3.1.  Centralized mobility management  . . . . . . . . . . . . .  7
     3.2.  Distributed mobility management  . . . . . . . . . . . . .  8
   4.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . .  9
   5.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   8.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 17
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 20
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23

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1.  Introduction

   In the past decade a fair number of network-layer mobility protocols
   have been standardized [RFC6275] [RFC5944] [RFC5380] [RFC6301]
   [RFC5213].  Although these protocols differ in terms of functions and
   associated message formats, they all employ a mobility anchor to
   allow a mobile node to remain reachable after it has moved to a
   different network.  The anchor point, among other tasks, ensures
   connectivity by forwarding packets destined to, or sent from, the
   mobile node.  It is a centrally deployed mobility anchor in the sense
   that the deployed architectures today have a small number of these
   anchors and the traffic of millions of mobile nodes in an operator
   network are typically managed by the same anchor.  Such a mobility
   anchor may still have to reside in the subscriber's provider network
   even when the subscriber is roaming to a visited network, in order
   that certain functions such as charging and billing can be performed
   more readily by the provider's network.  An example provider network
   is a Third Generation Partnership Project (3GPP) network.

   Distributed mobility management (DMM) is an alternative to the above
   centralized deployment.  The background behind the interests to study
   DMM are primarily in the following.

   (1)  Mobile users are, more than ever, consuming Internet content
        including that of local Content Delivery Networks (CDNs).  Such
        traffic imposes new requirements on mobile core networks for
        data traffic delivery.  To prevent exceeding the available core
        network capacity, service providers need to implement new
        strategies such as selective IPv4 traffic offload (e.g.,
        [RFC6909], 3GPP work items Local IP Access (LIPA) and Selected
        IP Traffic Offload (SIPTO) [TS.23.401]) through alternative
        access networks such as Wireless Local Area Network (WLAN)
        [Paper-Mobile.Data.Offloading].  In addition, a gateway
        selection mechanism takes the user proximity into account within
        the Evolved Packet Core (EPC) [TS.29303].  Yet these mechanisms
        were not pursued in the past owing to charging and billing
        considerations which require solutions beyond the mobility
        protocol.  Consequently, assigning a gateway anchor node from a
        visited network when roaming to the visited network has only
        recently been done and is limited to voice services.

        Both traffic offloading and CDN mechanisms could benefit from
        the development of mobile architectures with fewer hierarchical
        levels introduced into the data path by the mobility management
        system.  This trend of "flattening" the mobile networks works
        best for direct communications among peers in the same
        geographical area.  Distributed mobility management in the
        flattening mobile networks would anchor the traffic closer to

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        the point of attachment of the user.

   (2)  Today's mobile networks present service providers with new
        challenges.  Mobility patterns indicate that mobile nodes often
        remain attached to the same point of attachment for considerable
        periods of time [Paper-Locating.User].  Specific IP mobility
        management support is not required for applications that launch
        and complete their sessions while the mobile node is connected
        to the same point of attachment.  However, currently, IP
        mobility support is designed for always-on operation,
        maintaining all parameters of the context for each mobile
        subscriber for as long as they are connected to the network.
        This can result in a waste of resources and unnecessary costs
        for the service provider.  Infrequent node mobility coupled with
        application intelligence suggest that mobility support could be
        provided selectively such as in [I-D.bhandari-dhc-class-based-
        prefix] and [I-D.korhonen-6man-prefix-properties], thus reducing
        the amount of context maintained in the network.

   DMM may distribute the mobility anchors in the data-plane in
   flattening the mobility network such that the mobility anchors are
   positioned closer to the user; ideally, mobility agents could be
   collocated with the first-hop router.  Facilitated by the
   distribution of mobility anchors, it may be possible to selectively
   use or not use mobility protocol support depending on whether such
   support is needed or not.  It can thus reduce the amount of state
   information that must be maintained in various mobility agents of the
   mobile network.  It can then avoid the unnecessary establishment of
   mechanisms to forward traffic from an old to a new mobility anchor.

   This document compares distributed mobility management with
   centralized mobility management in Section 3.  The problems that can
   be addressed with DMM are summarized in Section 4.  The mandatory
   requirements as well as the optional requirements for network-layer
   distributed mobility management are given in Section 5.  Finally,
   security considerations are discussed in Section 6.

   The problem statement and the use cases [I-D.yokota-dmm-scenario] can
   be found in [Paper-Distributed.Mobility.Review].

2.  Conventions used in this document

2.1.  Terminology

   All the general mobility-related terms and their acronyms used in
   this document are to be interpreted as defined in the Mobile IPv6
   base specification [RFC6275], in the Proxy mobile IPv6 specification

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   [RFC5213], and in Mobility Related Terminology [RFC3753].  These
   terms include the following: mobile node (MN), correspondent node
   (CN), and home agent (HA) as per [RFC6275]; local mobility anchor
   (LMA) and mobile access gateway (MAG) as per [RFC5213], and context
   as per [RFC3753].

   In addition, this draft introduces the following terms.

   Centrally deployed mobility anchors

      refer to the mobility management deployments in which there are
      very few mobility anchors and the traffic of millions of mobile
      nodes in an operator network are managed by the same anchor.

   Centralized mobility management

      makes use of centrally deployed mobility anchors.

   Distributed mobility management

      is not centralized so that traffic does not need to traverse
      centrally deployed mobility anchors far from the optimal route.

   Hierarchical mobile network

      has a hierarchy of network elements arranged into multiple
      hierarchical levels which are introduced into the data path by the
      mobility management system.

   Flattening mobile network

      refers to the hierarchical mobile network which is going through
      the trend of reducing its number of hierarchical levels.

   Flatter mobile network

      has fewer hierarchical levels compared to a hierarchical mobile

   Mobility context

      is the collection of information required to provide mobility
      management support for a given mobile node.

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3.  Centralized versus distributed mobility management

   Mobility management is needed because the IP address of a mobile node
   may change as the node moves.  Mobility management functions may be
   implemented at different layers of the protocol stack.  At the IP
   (network) layer, mobility management can be client-based or network-

   An IP-layer mobility management protocol is typically based on the
   principle of distinguishing between a session identifier and a
   forwarding address and maintaining a mapping between the two.  In
   Mobile IP, the new IP address of the mobile node after the node has
   moved is the forwarding address, whereas the original IP address
   before the mobile node moves serves as the session identifier.  The
   location management (LM) information is kept by associating the
   forwarding address with the session identifier.  Packets addressed to
   the session identifier will first route to the original network which
   re-directs them using the forwarding address to deliver to the
   session.  Re-directing packets this way can result in long routes.
   An existing optimization routes directly using the forwarding address
   of the host, and such is a host-based solution.

   The next two subsections explain centralized and distributed mobility
   management functions in the network.

3.1.  Centralized mobility management

   In centralized mobility management, the location information in terms
   of a mapping between the session identifier and the forwarding
   address is kept at a single mobility anchor, and packets destined to
   the session identifier are forwarded via this anchor.  In other
   words, such mobility management systems are centralized in both the
   control plane and the data plane (mobile node IP traffic).

   Many existing mobility management deployments make use of centralized
   mobility anchoring in a hierarchical network architecture, as shown
   in Figure 1.  Examples are the home agent (HA) and local mobility
   anchor (LMA) serving as the anchors for the mobile node (MN) and
   Mobile Access Gateway (MAG) in Mobile IPv6 [RFC6275] and in Proxy
   Mobile IPv6 [RFC5213] respectively.  Cellular networks such as the
   3GPP General Packet Radio System (GPRS) networks and 3GPP Evolved
   Packet System (EPS) networks employ centralized mobility management
   too.  In the 3GPP GPRS network, the Gateway GPRS Support Node (GGSN),
   Serving GPRS Support Node (SGSN) and Radio Network Controller (RNC)
   constitute a hierarchy of anchors.  In the 3GPP EPS network, the
   Packet Data Network Gateway (P-GW) and Serving Gateway (S-GW)
   constitute another hierarchy of anchors.

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        3GPP GPRS                3GPP EPS                MIP/PMIP
         +------+                +------+                +------+
         | GGSN |                | P-GW |                |HA/LMA|
         +------+                +------+                +------+
            /\                      /\                      /\
           /  \                    /  \                    /  \
          /    \                  /    \                  /    \
         /      \                /      \                /      \
        /        \              /        \              /        \
       /          \            /          \            /          \
      /            \          /            \          /            \
  +------+      +------+  +------+      +------+  +------+      +------+
  | SGSN |      | SGSN |  | S-GW |      | S-GW |  |MN/MAG|      |MN/MAG|
  +------+      +------+  +------+      +------+  +------+      +------+
     /\            /\
    /  \          /  \
   /    \        /    \
+---+  +---+  +---+  +---+
|RNC|  |RNC|  |RNC|  |RNC|
+---+  +---+  +---+  +---+

   Figure 1.  Centralized mobility management.

3.2.  Distributed mobility management

   Mobility management functions may also be distributed in the data
   plane to multiple networks as shown in Figure 2, so that a mobile
   node in any of these networks may be served by a nearby function with
   appropriate forwarding management (FM) capability.

                    +------+  +------+  +------+  +------+
                    |  FM  |  |  FM  |  |  FM  |  |  FM  |
                    +------+  +------+  +------+  +------+
                                         | MN |

   Figure 2.  Distributed mobility management.

   DMM is distributed in the data plane, whereas the control plane may
   either be centralized or distributed [I-D.yokota-dmm-scenario].  The
   former case implicitly assumes separation of data and control planes
   as described in [I-D.wakikawa-netext-pmip-cp-up-separation].  While
   mobility management can be distributed, it is not necessary for other
   functions such as subscription management, subscription database, and
   network access authentication to be similarly distributed.

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   A distributed mobility management scheme for a flattening mobile
   network consisting of access nodes is proposed in [Paper-
   Distributed.Dynamic.Mobility].  Its benefits over centralized
   mobility management have been shown through simulations [Paper-
   Distributed.Centralized.Mobility].  Moreover, the (re)use and
   extension of existing protocols in the design of both fully
   distributed mobility management [Paper-Migrating.Home.Agents] [Paper-
   Distributed.Mobility.SAE] and partially distributed mobility
   management [Paper-Distributed.Mobility.PMIP] [Paper-
   Distributed.Mobility.MIP] have been reported in the literature.
   Therefore, before designing new mobility management protocols for a
   future distributed architecture, it is recommended to first consider
   whether existing mobility management protocols can be extended.

4.  Problem Statement

   The problems that can be addressed with DMM are summarized in the

   PS1:  Non-optimal routes

         Forwarding via a centralized anchor often results in non-
         optimal routes, thereby increasing the end-to-end delay.  The
         problem is manifested, for example, when accessing a nearby
         server or servers of a Content Delivery Network (CDN), or when
         receiving locally available IP multicast or sending IP
         multicast packets.  (Existing route optimization is only a
         host-based solution.  On the other hand, localized routing with
         PMIPv6 [RFC6705] addresses only a part of the problem where
         both the MN and the correspondent node (CN) are attached to the
         same MAG, and it is not applicable when the CN does not behave
         like an MN.)

   PS2:  Divergence from other evolutionary trends in network
         architectures such as distribution of content delivery.

         Mobile networks have generally been evolving towards a flatter
         and flatter network.  Centralized mobility management, which is
         non-optimal with a flatter network architecture, does not
         support this evolution.

   PS3:  Lack of scalability of centralized tunnel management and
         mobility context maintenance

         Setting up tunnels through a central anchor and maintaining
         mobility context for each MN usually requires more concentrated
         resources in a centralized design, thus reducing scalability.

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         Distributing the tunnel maintenance function and the mobility
         context maintenance function among different network entities
         with proper signaling protocol design can avoid increasing the
         concentrated resources with an increasing number of MNs.

   PS4:  Single point of failure and attack

         Centralized anchoring designs may be more vulnerable to single
         points of failures and attacks than a distributed system.  The
         impact of a successful attack on a system with centralized
         mobility management can be far greater as well.

   PS5:  Unnecessary mobility support to clients that do not need it

         IP mobility support is usually provided to all MNs.  Yet it is
         not always required, and not every parameter of mobility
         context is always used.  For example, some applications or
         nodes do not need a stable IP address during a handover to
         maintain session continuity.  Sometimes, the entire application
         session runs while the MN does not change the point of
         attachment.  Besides, some sessions, e.g., SIP-based sessions,
         can handle mobility at the application layer and hence do not
         need IP mobility support; it is then unnecessary to provide IP
         mobility support for such sessions.

   PS6:  Mobility signaling overhead with peer-to-peer communication

         Wasting resources when mobility signaling (e.g., maintenance of
         the tunnel, keep alive signaling, etc.) is not turned off for
         peer-to-peer communication.

   PS7:  Deployment with multiple mobility solutions

         There are already many variants and extensions of MIP as well
         mobility solutions at other layers.  Deployment of new mobility
         management solutions can be challenging, and debugging
         difficult, when they co-exist with solutions already deployed
         in the field.

   PS8:  Duplicate multicast traffic

         IP multicast distribution over architectures using IP mobility
         solutions (e.g., [RFC6224]) may lead to convergence of
         duplicated multicast subscriptions towards the downstream
         tunnel entity (e.g., MAG in PMIPv6).  Concretely, when
         multicast subscription for individual mobile nodes is coupled
         with mobility tunnels (e.g., PMIPv6 tunnel), duplicate
         multicast subscription(s) is prone to be received through

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         different upstream paths.  This problem may also exist or be
         more severe in a distributed mobility environment.

5.  Requirements

   After comparing distributed mobility management against centralized
   deployment in Section 3 and describing the problems in Section 4,
   this section identifies the following requirements:

   REQ1:  Distributed mobility management

          IP mobility, network access and forwarding solutions provided
          by DMM MUST enable traffic to avoid traversing single mobility
          anchor far from the optimal route.

          This requirement on distribution is in the data plane only.
          It does not impose constraints on whether the control plane
          should be distributed or centralized.  However, if the control
          plane is centralized while the data plane is distributed, it
          is implicit that the control plane and data plane need to
          separate (Section 3.2).

          Motivation: This requirement is motivated by current trends in
          network evolution: (a) it is cost- and resource-effective to
          cache contents, and the caching (e.g., CDN) servers are
          distributed so that each user in any location can be close to
          one of the servers; (b) the significantly larger number of
          mobile nodes and flows call for improved scalability; (c)
          single points of failure are avoided in a distributed system;
          (d) threats against centrally deployed anchors, e.g., home
          agent and local mobility anchor, are mitigated in a
          distributed system.

          This requirement addresses the problems PS1, PS2, PS3, and PS4
          described in Section 4.

   REQ2:  Bypassable network-layer mobility support for each application

          DMM solutions MUST enable network-layer mobility but it MUST
          be possible for any individual active application session
          (flow) to not use it.  Mobility support is needed, for
          example, when a mobile host moves and an application cannot
          cope with a change in the IP address.  Mobility support is
          also needed when a mobile router changes its IP address as it
          moves together with a host and, in the presence of ingress
          filtering, an application in the host is interrupted.  However

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          mobility support at the network-layer is not always needed; a
          mobile node can often be stationary, and mobility support can
          also be provided at other layers.  It is then not always
          necessary to maintain a stable IP address or prefix for an
          active application session.

          Different active sessions can also differ in whether network-
          layer mobility support is needed.  IP mobility, network access
          and forwarding solutions provided by DMM MUST then enable the
          possibility of independent handling for each application
          session of a user or mobile device.

          The handling of mobility management to the granularity of an
          individual session of a user/device SHOULD need proper session
          identification in addition to user/device identification.

          Motivation: The motivation of this requirement is to enable
          more efficient forwarding and more efficient use of network
          resources by selecting an IP address or prefix according to
          whether mobility support is needed and by not maintaining
          context at the mobility anchor when there is no such need.

          This requirement addresses the problems PS5 and PS6 described
          in Section 4.

   REQ3:  IPv6 deployment

          DMM solutions SHOULD target IPv6 as the primary deployment
          environment and SHOULD NOT be tailored specifically to support
          IPv4, in particular in situations where private IPv4 addresses
          and/or NATs are used.

          Motivation: This requirement conforms to the general
          orientation of IETF work.  DMM deployment is foreseen in mid-
          to long-term horizon, when IPv6 is expected to be far more
          common than today.

          This requirement avoids the unnecessarily complexity in
          solving the problems in Section 4 for IPv4, which will not be
          able to use some of the IPv6-specific features.

   REQ4:  Existing mobility protocols

          A DMM solution MUST first consider reusing and extending IETF-
          standardized protocols before specifying new protocols.

          Motivation: Reuse of existing IETF work is more efficient and
          less error-prone.

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          This requirement attempts to avoid the need of new protocols
          development and therefore their potential problems of being
          time-consuming and error-prone.

   REQ5:  Coexistence with deployed networks/hosts and operability
          across different networks

          A DMM solution may require loose, tight or no integration into
          existing mobility protocols and host IP stack.  Regardless of
          the integration level, DMM implementations MUST be able to
          coexist with existing network deployments, end hosts and
          routers that may or may not implement existing mobility
          protocols.  Furthermore, a DMM solution SHOULD work across
          different networks, possibly operated as separate
          administrative domains, when the needed mobility management
          signaling, forwarding, and network access are allowed by the
          trust relationship between them.

          Motivation: (a) to preserve backwards compatibility so that
          existing networks and hosts are not affected and continue to
          function as usual, and (b) enable inter-domain operation if

          This requirement addresses the problem PS7 described in
          Section 4.

   REQ6:  Operation and Management considerations.

          A DMM solution needs to consider configuring a device,
          monitoring the current operational state of a device,
          responding to events that impact the device, possibly by
          modifying the configuration and storing the data in a format
          that can be analyzed later.  Different management protocols
          are available.  For example:

          (a)  SNMP [RFC1157] with definition of standardized management
               information base MIB objects for DMM, that allows
               monitoring traffic steering in a consistent manner across
               different devices,

          (b)  NETCONF [RFC6241] with definition of standardized YANG
               [RFC6020] modules for DMM to achieve a standardized

          (c)  syslog [RFC3164] which is a one-way protocol allowing a
               device to report significant events to a log analyzer in
               a network management system.

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          (d)  IP Flow Information Export (IPFIX) Protocol, which serves
               as a means for transmitting traffic flow information over
               the network [RFC7011], with a formal description of IPFIX
               Information Elements [RFC7012].

          It is not the goal of the requirements document to impose
          which management protocol(s) should be used.  An inventory of
          the management protocols and data models is covered in RFC

          The following lists the operation and management
          considerations required for a DMM solution; the list may not
          be exhaustive and may be expanded according to the needs of
          the solutions:

          A DMM solution MUST describe in what environment and how it
          can be scalably deployed and managed.

          A DMM solution MUST support mechanisms to test if the DMM
          solution is working properly.  For example, when a DMM
          solution employs traffic indirection to support a mobility
          session, implementations MUST support mechanisms to test that
          the appropriate traffic indirection operations are in place,
          including the setup of traffic indirection and the subsequent
          teardown of the indirection to release the associated network
          resources when the mobility session has closed.

          A DMM solution SHOULD expose the operational state of DMM to
          the administrators of the DMM entities.  For example, when a
          DMM solution employs separation between session identifier and
          forwarding address, it should expose the association between

          When flow mobility is supported by a DMM solution, the
          solution SHOULD support means to correlate the flow routing
          policies and the observed forwarding actions.

          A DMM solution SHOULD support mechanisms to check the liveness
          of forwarding path.  If the DMM solution sends periodic update
          refresh messages to configure the forwarding path, the refresh
          period SHOULD be configurable and a reasonable default
          configuration value proposed.  Information collected can be
          logged or made available with protocols such as SNMP
          [RFC1157], NETCONF [RFC6241], IPFIX [RFC7011], or syslog

          A DMM solution MUST provide fault management and monitoring

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          mechanisms to manage situations where update of the mobility
          session or the data path fails.  The system must also be able
          to handle situations where a mobility anchor with ongoing
          mobility sessions fails.

          A DMM solution SHOULD be able to monitor usage of DMM
          protocol.  When a DMM solution uses an existing protocol, the
          techniques already defined for that protocol SHOULD be used to
          monitor the DMM operation.  When these techniques are
          inadequate, new techniques MUST be developed.

          In particular, the DMM solution SHOULD

          (a)  be able to monitor the number of mobility sessions per
               user as well as their average duration.

          (b)  provide indication on DMM performance such as

               1  the handover delay which includes the time necessary
                  to re-establish the forwarding path when the point of
                  attachment changes,

               2  the protocol reactivity which is the time between
                  handover events such as the attachment to a new access
                  point and the completion of the mobility session

          (c)  provide means to measure the signaling cost of the DMM

          (d)  if tunneling is used for traffic redirection, monitor

               1  the number of tunnels,

               2  their transmission and reception information,

               3  the used encapsulation method and overhead

               4  the security used at a node level.

          DMM solutions SHOULD support standardized configuration with
          NETCONF [RFC6241], using YANG [RFC6020] modules, which SHOULD
          be created for DMM when needed for such configuration.
          However, if a DMM solution creates extensions to MIPv6 or
          PMIPv6, the allowed addition of the definition of management
          information base (MIB) objects to MIPv6 MIB [RFC4295] or
          PMIPv6 MIB [RFC6475] needed for the control and monitoring of

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          the protocol extensions SHOULD be limited to read-only

          Motivation: A DMM solution that is designed from the beginning
          for operability and manageability can avoid difficulty or
          incompatibility to implement efficient operations and
          management solutions.

          These requirements avoid DMM designs that make operations and
          management difficult or costly.

   REQ7:  Security considerations

          A DMM solution MUST support any security protocols and
          mechanisms needed to secure the network and to make continuous
          security improvements.  In addition, with security taken into
          consideration early in the design, a DMM solution MUST NOT
          introduce new security risks, or amplify existing security
          risks, that cannot be mitigated by existing security protocols
          and mechanisms.

          Motivation: Various attacks such as impersonation, denial of
          service, man-in-the-middle attacks, and so on, may be launched
          in a DMM deployment.  For instance, an illegitimate node may
          attempt to access a network providing DMM.  Another example is
          that a malicious node can forge a number of signaling messages
          thus redirecting traffic from its legitimate path.
          Consequently, the specific node or nodes to which the traffic
          is redirected may be under a denial of service attack, whereas
          other nodes do not receive their traffic.  Accordingly,
          security mechanisms/protocols providing access control,
          integrity, authentication, authorization, confidentiality,
          etc. should be used to protect the DMM entities as they are
          already used to protect against existing networks and existing
          mobility protocols defined in IETF.  Yet if a candidate DMM
          solution is such that even the proper use of these existing
          security mechanisms/protocols are unable to provide sufficient
          security protection, that candidate DMM solution is causing
          uncontrollable security problems.

          This requirement prevents a DMM solution from introducing
          uncontrollable problems of potentially insecure mobility
          management protocols which make deployment infeasible because
          platforms conforming to the protocols are at risk for data
          loss and numerous other dangers, including financial harm to
          the users.

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   REQ8:  Multicast considerations

          DMM SHOULD enable multicast solutions to be developed to avoid
          network inefficiency in multicast traffic delivery.

          Motivation: Existing multicast deployment have been introduced
          after completing the design of the reference mobility
          protocol, often leading to network inefficiency and non-
          optimal forwarding for the multicast traffic.  Instead DMM
          should consider multicast early so that the multicast
          solutions can better consider efficiency nature in the
          multicast traffic delivery (such as duplicate multicast
          subscriptions towards the downstream tunnel entities).  The
          multicast solutions should then avoid restricting the
          management of all IP multicast traffic to a single host
          through a dedicated (tunnel) interface on multicast-capable
          access routers.

          This requirement addresses the problems PS1 and PS8 described
          in Section 4.

6.  Security Considerations

   Please refer to the discussion under Security requirement in Section

7.  IANA Considerations


8.  Contributors

   This requirements document is a joint effort among numerous
   participants working in a team.  Valuable comments and suggestions in
   various reviews from the following area directors and IESG members
   have also contributed to much improvements: Russ Housley, Catherine
   Meadows, Adrian Farrel, Barry Leiba, Alissa Cooper, Ted Lemon, Brian
   Haberman, Stephen Farrell, Joel Jaeggli, Alia Atlas, and Benoit
   Claise.  In addition to the authors, each of the following has made
   very significant and important contributions to the working group
   draft in this work:

   Charles E. Perkins
   Huawei Technologies

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   Melia Telemaco
   Alcatel-Lucent Bell Labs

   Elena Demaria
   Telecom Italia
   via G. Reiss Romoli, 274, TORINO, 10148, Italy

   Jong-Hyouk Lee
   Sangmyung University, Korea

   Kostas Pentikousis
   EICT GmbH

   Tricci So

   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av.  Universidad, 30, Leganes, Madrid 28911, Spain

   Peter McCann
   Huawei Technologies

   Seok Joo Koh
   Kyungpook National University, Korea

   Wen Luo
   No.68, Zijinhua RD,Yuhuatai District, Nanjing, Jiangsu 210012, China

   Sri Gundavelli

   Hui Deng
   China Mobile

   Marco Liebsch

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   NEC Laboratories Europe

   Carl Williams
   MCSR Labs

   Seil Jeon
   Instituto de Telecomunicacoes, Aveiro

   Sergio Figueiredo
   Universidade de Aveiro

   Stig Venaas

   Luis Miguel Contreras Murillo
   Telefonica I+D

   Juan Carlos Zuniga

   Alexandru Petrescu

   Georgios Karagiannis
   University of Twente

   Julien Laganier

   Wassim Michel Haddad

   Dirk von Hugo
   Deutsche Telekom Laboratories

   Ahmad Muhanna
   Award Solutions

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   Byoung-Jo Kim
   ATT Labs

   Hassan Ali-Ahmad

   Alper Yegin

   David Harrington
   Effective Software

9.  References

9.1.  Normative References

   [RFC1157]  Case, J., Fedor, M., Schoffstall, M., and J. Davin,
              "Simple Network Management Protocol (SNMP)", STD 15,
              RFC 1157, May 1990.

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

   [RFC3164]  Lonvick, C., "The BSD Syslog Protocol", RFC 3164,
              August 2001.

   [RFC3753]  Manner, J. and M. Kojo, "Mobility Related Terminology",
              RFC 3753, June 2004.

   [RFC4295]  Keeni, G., Koide, K., Nagami, K., and S. Gundavelli,
              "Mobile IPv6 Management Information Base", RFC 4295,
              April 2006.

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

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)",
              RFC 6241, June 2011.

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

   [RFC6475]  Keeni, G., Koide, K., Gundavelli, S., and R. Wakikawa,
              "Proxy Mobile IPv6 Management Information Base", RFC 6475,
              May 2012.

   [RFC6632]  Ersue, M. and B. Claise, "An Overview of the IETF Network
              Management Standards", RFC 6632, June 2012.

   [RFC7011]  Claise, B., Trammell, B., and P. Aitken, "Specification of
              the IP Flow Information Export (IPFIX) Protocol for the
              Exchange of Flow Information", STD 77, RFC 7011,
              September 2013.

   [RFC7012]  Claise, B. and B. Trammell, "Information Model for IP Flow
              Information Export (IPFIX)", RFC 7012, September 2013.

9.2.  Informative References

              Bhandari, S., Halwasia, G., Gundavelli, S., Deng, H.,
              Thiebaut, L., Korhonen, J., and I. Farrer, "DHCPv6 class
              based prefix", draft-bhandari-dhc-class-based-prefix-05
              (work in progress), July 2013.

              Korhonen, J., Patil, B., Gundavelli, S., Seite, P., and D.
              Liu, "IPv6 Prefix Properties",
              draft-korhonen-6man-prefix-properties-02 (work in
              progress), July 2013.

              Wakikawa, R., Pazhyannur, R., Gundavelli, S., and C.
              Perkins, "Separation of Control and User Plane for Proxy
              Mobile IPv6",
              draft-wakikawa-netext-pmip-cp-up-separation-03 (work in
              progress), April 2014.

              Yokota, H., Seite, P., Demaria, E., and Z. Cao, "Use case
              scenarios for Distributed Mobility Management",
              draft-yokota-dmm-scenario-00 (work in progress),
              October 2010.

              Bertin, P., Bonjour, S., and J-M. Bonnin, "A Distributed
              or Centralized Mobility",  Proceedings of Global

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              Communications Conference  (GlobeCom), December 2009.

              Bertin, P., Bonjour, S., and J-M. Bonnin, "A Distributed
              Dynamic Mobility Management Scheme Designed for Flat IP
              Architectures",  Proceedings of 3rd International
              Conference on New Technologies, Mobility and Security
              (NTMS), 2008.

              Chan, H., "Distributed Mobility Management with Mobile
              IP",  Proceedings of IEEE International Communication
              Conference (ICC) Workshop on Telecommunications: from
              Research to Standards, June 2012.

              Chan, H., "Proxy Mobile IP with Distributed Mobility
              Anchors",  Proceedings of GlobeCom Workshop  on Seamless
              Wireless Mobility, December 2010.

              Chan, H., Yokota, H., Xie, J., Seite, P., and D. Liu,
              "Distributed and Dynamic Mobility Management in Mobile
              Internet: Current Approaches and Issues",  Journal of
              Communications, vol. 6, no. 1, pp. 4-15, February 2011.

              Fisher, M., Anderson, F., Kopsel, A., Schafer, G., and M.
              Schlager, "A Distributed IP Mobility Approach for 3G SAE",
               Proceedings of the 19th International Symposium on
              Personal, Indoor and Mobile Radio Communications (PIMRC),

              Kirby, G., "Locating the User",  Communication
              International, 1995.

              Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home
              Agents Towards Internet-scale Mobility Deployments",
               Proceedings of the ACM 2nd CoNEXT Conference  on Future
              Networking Technologies, December 2006.

              Lee, K., Lee, J., Yi, Y., Rhee, I., and S. Chong, "Mobile
              Data Offloading: How Much Can WiFi Deliver?",  SIGCOMM
              2010, 2010.

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   [RFC5380]  Soliman, H., Castelluccia, C., ElMalki, K., and L.
              Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
              Management", RFC 5380, October 2008.

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

   [RFC6224]  Schmidt, T., Waehlisch, M., and S. Krishnan, "Base
              Deployment for Multicast Listener Support in Proxy Mobile
              IPv6 (PMIPv6) Domains", RFC 6224, April 2011.

   [RFC6301]  Zhu, Z., Wakikawa, R., and L. Zhang, "A Survey of Mobility
              Support in the Internet", RFC 6301, July 2011.

   [RFC6705]  Krishnan, S., Koodli, R., Loureiro, P., Wu, Q., and A.
              Dutta, "Localized Routing for Proxy Mobile IPv6",
              RFC 6705, September 2012.

   [RFC6909]  Gundavelli, S., Zhou, X., Korhonen, J., Feige, G., and R.
              Koodli, "IPv4 Traffic Offload Selector Option for Proxy
              Mobile IPv6", RFC 6909, April 2013.

              3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", 3GPP TR 23.401 10.10.0, March 2013.

              3GPP, "Domain Name System Procedures; Stage 3", 3GPP
              TR 23.303 11.2.0, September 2012.

Authors' Addresses

   H Anthony Chan (editor)
   Huawei Technologies
   5340 Legacy Dr. Building 3, Plano, TX 75024, USA

   Dapeng Liu
   China Mobile
   Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China

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   Pierrick Seite
   4, rue du Clos Courtel, BP 91226, Cesson-Sevigne 35512, France

   Hidetoshi Yokota
   KDDI Lab
   2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan

   Jouni Korhonen
   Broadcom Communications
   Porkkalankatu 24, FIN-00180 Helsinki, Finland

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