path: root/doc/rfc/rfc4885.txt

Network Working Group                                           T. Ernst
Request for Comments: 4885                                         INRIA
Category: Informational                                        H-Y. Lach
                                                                Motorola
                                                               July 2007


                  Network Mobility Support Terminology

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines a terminology for discussing network mobility
   (NEMO) issues and solution requirements.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Architectural Components . . . . . . . . . . . . . . . . . . .  3
     2.1.  Mobile Network (NEMO)  . . . . . . . . . . . . . . . . . .  5
     2.2.  Mobile Subnet  . . . . . . . . . . . . . . . . . . . . . .  5
     2.3.  Mobile Router (MR) . . . . . . . . . . . . . . . . . . . .  6
     2.4.  Egress Interface . . . . . . . . . . . . . . . . . . . . .  6
     2.5.  Ingress Interface  . . . . . . . . . . . . . . . . . . . .  6
     2.6.  Mobile Network Prefix (MNP)  . . . . . . . . . . . . . . .  6
     2.7.  Mobile Network Node (MNN)  . . . . . . . . . . . . . . . .  6
     2.8.  Correspondent Node (CN)  . . . . . . . . . . . . . . . . .  7
     2.9.  Correspondent Router (CR)  . . . . . . . . . . . . . . . .  7
     2.10. Correspondent Entity (CE)  . . . . . . . . . . . . . . . .  7
   3.  Functional Terms . . . . . . . . . . . . . . . . . . . . . . .  7
     3.1.  Local Fixed Node (LFN) . . . . . . . . . . . . . . . . . .  8
     3.2.  Visiting Mobile Node (VMN) . . . . . . . . . . . . . . . .  8
     3.3.  Local Mobile Node (LMN)  . . . . . . . . . . . . . . . . .  9
     3.4.  NEMO-Enabled Node (NEMO-Node)  . . . . . . . . . . . . . .  9
     3.5.  MIPv6-Enabled Node (MIPv6-Node)  . . . . . . . . . . . . .  9
   4.  Nested Mobility Terms  . . . . . . . . . . . . . . . . . . . .  9
     4.1.  Nested Mobile Network (nested-NEMO)  . . . . . . . . . . .  9
     4.2.  Root-NEMO  . . . . . . . . . . . . . . . . . . . . . . . .  9
     4.3.  Parent-NEMO  . . . . . . . . . . . . . . . . . . . . . . . 10



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     4.4.  Sub-NEMO . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.5.  Root-MR  . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.6.  Parent-MR  . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.7.  Sub-MR . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.8.  Depth  . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   5.  Multihoming Terms  . . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  Multihomed Host or MNN . . . . . . . . . . . . . . . . . . 11
     5.2.  Multihomed Mobile Router . . . . . . . . . . . . . . . . . 11
     5.3.  Multihomed Mobile Network (multihomed-NEMO)  . . . . . . . 12
     5.4.  Nested Multihomed Mobile Network . . . . . . . . . . . . . 12
     5.5.  Split-NEMO . . . . . . . . . . . . . . . . . . . . . . . . 12
     5.6.  Illustration . . . . . . . . . . . . . . . . . . . . . . . 12
   6.  Home Network Model Terms . . . . . . . . . . . . . . . . . . . 14
     6.1.  Home Link  . . . . . . . . . . . . . . . . . . . . . . . . 14
     6.2.  Home Network . . . . . . . . . . . . . . . . . . . . . . . 14
     6.3.  Home Address . . . . . . . . . . . . . . . . . . . . . . . 14
     6.4.  Mobile Home Network  . . . . . . . . . . . . . . . . . . . 14
     6.5.  Distributed Home Network . . . . . . . . . . . . . . . . . 14
     6.6.  Mobile Aggregated Prefix . . . . . . . . . . . . . . . . . 15
     6.7.  Aggregated Home Network  . . . . . . . . . . . . . . . . . 15
     6.8.  Extended Home Network  . . . . . . . . . . . . . . . . . . 15
     6.9.  Virtual Home Network . . . . . . . . . . . . . . . . . . . 15
   7.  Mobility Support Terms . . . . . . . . . . . . . . . . . . . . 15
     7.1.  Host Mobility Support  . . . . . . . . . . . . . . . . . . 15
     7.2.  Network Mobility Support (NEMO Support)  . . . . . . . . . 15
     7.3.  NEMO Basic Support . . . . . . . . . . . . . . . . . . . . 15
     7.4.  NEMO Extended Support  . . . . . . . . . . . . . . . . . . 16
     7.5.  NEMO Routing Optimization (NEMO RO)  . . . . . . . . . . . 16
     7.6.  MRHA Tunnel  . . . . . . . . . . . . . . . . . . . . . . . 16
     7.7.  Pinball Route  . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 17
     10.2. Informative References . . . . . . . . . . . . . . . . . . 17
















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1.  Introduction

   Network mobility support is concerned with managing the mobility of
   an entire network.  This arises when a router connecting a network to
   the Internet dynamically changes its point of attachment to the fixed
   infrastructure, thereby causing the reachability of the entire
   network to be changed in relation to the fixed Internet topology.
   Such a network is referred to as a mobile network.  Without
   appropriate mechanisms to support network mobility, sessions
   established between nodes in the mobile network and the global
   Internet cannot be maintained after the mobile router changes its
   point of attachment.  As a result, existing sessions would break and
   connectivity to the global Internet would be lost.

   This document defines the specific terminology needed to describe the
   problem space, the design goals [1], and the solutions for network
   mobility support.  This terminology aims to be consistent with the
   usual IPv6 terminology [2] and the generic mobility-related terms
   already defined in the Mobility Related Terminology [3] and in the
   Mobile IPv6 specification [4].  Some terms introduced in this
   document may only be useful for defining the problem scope and
   functional requirements of network mobility support.

   Note that the abbreviation NEMO stands for either "a NEtwork that is
   MObile" or "NEtwork MObility".  The former (see Section 2.1) is used
   as a noun, e.g., "a NEMO" meaning "a mobile network".  The latter
   (see Section 7) refers to the concept of "network mobility", as in
   "NEMO Basic Support", and is also the working group's name.

   Section 2 introduces terms to define the architecture, while terms
   needed to emphasize the distinct functionalities of those
   architectural components are described in Section 3.  Section 4,
   Section 5, and Section 6 describe terms pertaining to nested
   mobility, multihoming, and different configurations of mobile
   networks at home, respectively.  The different types of mobility are
   defined in Section 7.  The last section lists miscellaneous terms
   that do not fit into any other section.

2.  Architectural Components

   A mobile network is composed of one or more mobile IP-subnets and is
   viewed as a single unit.  This network unit is connected to the
   Internet by means of one or more mobile routers (MRs).  Nodes behind
   the MR (referred to as MNNs) primarily comprise fixed nodes (nodes
   unable to change their point of attachment while maintaining ongoing
   sessions), and possibly mobile nodes (nodes able to change their
   point of attachment while maintaining ongoing sessions).  In most




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   cases, the internal structure of the mobile network will be stable
   (no dynamic change of the topology), but this is not always true.

   Figure 1 illustrates the architectural components involved in network
   mobility and are defined in the following paragraphs: Mobile Router
   (MR), Mobile Network (NEMO), Mobile Network Node (MNN), "ingress
   interface", "egress interface", and Correspondent Node (CN).  The
   other terms, "access router" (AR), "Fixed Node (FN)", "Mobile Node
   (MN)", "home agent" (HA), "home link", and "foreign link", are not
   terms specific to network mobility and thus are defined in [3].

                     _
               CN ->|_|-| Internet
                        |  _____
                        |-|     |       |<- home link
                       _  |     |-|  _  |  _
                    |-|_|-|_____| |-|_|-|-|_|<- HA (Home Agent)
                    |  \                |  _
     foreign link ->|  ^                |-|_|<- MR (Mobile Router)
                       .. AR (access    ___|___
                             router)     _|  |_
                                        |_|  |_|
                                         ^    ^
                                      MNN1    MNN2


                 Figure 1: Mobile Network on the Home Link

   Figure 2 shows a single mobile subnet.  Figure 3 illustrates a larger
   mobile network comprising several subnets, attached to a foreign
   link.

                             _
                       CN ->|_|-|
                                |  _____
                   _  |         |-|     |       |<- home link
                  |_|-|  _  |  _  |     |-|  _  |  _
         2 MNNs -> _  |-|_|-|-|_|-|_____| |-|_|-|-|_|<- HA
                  |_|-|  .  |  \             \  |
                      |  .  |<- foreign      ^AR
      mobile subnet ->   .       link
                         .
                         ^ MR

             Figure 2: Single Mobile Subnet on a Foreign Link






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                               _
                          CN->|_|-|
       mobile subnet->|           |  _____
                   _  |           |-|     |       |<- home link
            MNN1->|_|-|'i'_'e'|  _  |     |-|  _  |  _
                      |--|_|--|-|_|-|_____| |-|_|-|-|_|<- HA
                       'i'|   |  \                |
                      ____|__ |
       mobile subnet-^ _| .   |<- foreign
                      |_| .       link
                MNN2 -^   .
                          ^
                          MR

   'i': MR's ingress interface
   'e': MR's egress interface

        Figure 3: Larger Mobile Network Made up of 2 Mobile Subnets

   At the network layer, MRs get access to the global Internet from an
   Access Router (AR) on a visited link.  An MR maintains the Internet
   connectivity for the entire mobile network.  A given MR has one or
   more egress interfaces and one or more ingress interfaces.  When
   forwarding a packet to the Internet, the packet is transmitted
   upstream through one of the MR's egress interfaces to the AR; when
   forwarding a packet from the AR down to the mobile network, the
   packet is transmitted downstream through one of the MR's ingress
   interfaces.

2.1.  Mobile Network (NEMO)

   As defined in [3]:

   An entire network, moving as a unit, which dynamically changes its
   point of attachment to the Internet and thus its reachability in the
   topology.  The mobile network is composed of one or more IP-subnets
   and is connected to the global Internet via one or more Mobile
   Routers (MR).  The internal configuration of the mobile network is
   assumed to be relatively stable with respect to the MR.

   Rearrangement of the mobile network and changing the attachment point
   of the egress interface to the foreign link are orthogonal processes
   and do no affect each other.

2.2.  Mobile Subnet

   A link (subnet) that comprises, or is located within, the mobile
   network.



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2.3.  Mobile Router (MR)

   As defined in [3]:

   A router capable of changing its point of attachment to the Internet,
   moving from one link to another link.  The MR is capable of
   forwarding packets between two or more interfaces, and possibly
   running a dynamic routing protocol modifying the state by which it
   does packet forwarding.

   An MR acts as a gateway between an entire mobile network and the rest
   of the Internet, and has one or more egress interfaces and one or
   more ingress interfaces.  Packets forwarded upstream to the rest of
   the Internet are transmitted through one of the MR's egress
   interfaces; packets forwarded downstream to the mobile network are
   transmitted through one of the MR's ingress interfaces.

2.4.  Egress Interface

   As defined in [3]:

   The network interface of an MR attached to the home link if the MR is
   at home, or attached to a foreign link, if the MR is in a foreign
   network.

2.5.  Ingress Interface

   As defined in [3]:

   The interface of an MR attached to a link inside the mobile network.

2.6.  Mobile Network Prefix (MNP)

   As defined in [3]:

   A bit string that consists of some number of initial bits of an IP
   address which identifies the entire mobile network within the
   Internet topology.  All nodes in a mobile network necessarily have an
   address containing this prefix.

2.7.  Mobile Network Node (MNN)

   As defined in [3]:

   Any node (host or router) located within a mobile network, either
   permanently or temporarily.  A Mobile Network Node may be either a
   fixed node (LFN) or a mobile node (either VMN or LMN).




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2.8.  Correspondent Node (CN)

   Any node that is communicating with one or more MNNs.  A CN could be
   either located within a fixed network or within a mobile network, and
   could be either fixed or mobile.

2.9.  Correspondent Router (CR)

   Refers to the entity that is capable of terminating a Route
   Optimization session on behalf of a Correspondent Node (see also NEMO
   Route Optimization in Section 7.5).

2.10.  Correspondent Entity (CE)

   Refers to the entity with which a Mobile Router or Mobile Network
   Node attempts to establish a Route Optimization session.  Depending
   on the Route Optimization approach, the Correspondent Entity may be a
   Correspondent Node or Correspondent Router (see also NEMO Route
   Optimization in Section 7.5).

3.  Functional Terms

   Within the term Mobile Network Node (MNN), we can distinguish between
   Local Fixed Nodes (LFN), Visiting Mobile Nodes (VMN), and Local
   Mobile Nodes (LMN).  The distinction is a property of how different
   types of nodes can move in the topology and is necessary to discuss
   issues related to mobility management and access control; however, it
   does not imply that network mobility or host mobility should be
   handled differently.  Nodes are classified according to their
   function and capabilities with the rationale that nodes with
   different properties may have different requirements.

   Figure 4 illustrates a VMN changing its point of attachment from its
   home link located outside the mobile network to within a mobile
   network.  The figure also illustrates an LMN changing its point of
   attachment within the mobile network.















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       mobile subnet 1 |  _      +++++++<<<+++++++++++
                       |-|_|-|   +                   +
              ++<<<LMN-|  \  |   +                 |-MR
              +              |   +          _____  |  _ HA_MR
              +        |  _  |   +         |     |-|-|_|
              + LMN _  |-|_|-|   _   |  _  |     |    _
              ++++>|_|-|  \  |--|_|--|-|_|-|_____|-|-|_|
                       |     |   ^   |  \          |    HA_VMN
                VMN _  |         MR                |
                   |_|-|                           |-VMN
                 ^    mobile subnet 2               +
                 +                                  +
                 ++++++++<<<+++++++++++++++++++++++++

   +++>>>+++ = changing point of attachment

                        Figure 4: LFN vs LMM vs VMN

   In a typical-use case of NEMO Basic Support [5], only the MR and the
   HA are NEMO-enabled.  LFNs are not MIPv6-enabled nor NEMO-enabled.
   On the other hand, a VMN or an LMN acting as a mobile router may be
   NEMO-enabled, whereas a VMN or an LMN acting as a mobile node may be
   MIPv6-enabled.

   For NEMO Extended Support, details of the capabilities are not yet
   known at the time of this writing, but NEMO-enabled nodes may be
   expected to implement some sort of Route Optimization.

3.1.  Local Fixed Node (LFN)

   A fixed node (FN), either a host or a router, that belongs to the
   mobile network and is unable to change its point of attachment while
   maintaining ongoing sessions.  Its address is taken from an MNP.

3.2.  Visiting Mobile Node (VMN)

   Either a mobile node (MN) or a mobile router (MR), assigned to a home
   link that doesn't belong to the mobile network and that is able to
   change its point of attachment while maintaining ongoing sessions.  A
   VMN that is temporarily attached to a mobile subnet (used as a
   foreign link) obtains an address on that subnet (i.e., the address is
   taken from an MNP).









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3.3.  Local Mobile Node (LMN)

   Either a mobile node (MN) or a mobile router (MR), assigned to a home
   link belonging to the mobile network and which is able to change its
   point of attachment while maintaining ongoing sessions.  Its address
   is taken from an MNP.

3.4.  NEMO-Enabled Node (NEMO-Node)

   A node that has been extended with network mobility support
   capabilities as described in NEMO specifications.

3.5.  MIPv6-Enabled Node (MIPv6-Node)

   A node that has been extended with host mobility support capabilities
   as defined in the Mobile IPv6 specification [4].

4.  Nested Mobility Terms

   Nested mobility occurs when there is more than one level of mobility,
   i.e., when a mobile network acts as an access network and allows
   visiting nodes to attach to it.  There are two cases of nested
   mobility:

   o  The attaching node is a single VMN (see Figure 4).  For instance,
      when a passenger carrying a mobile phone gets Internet access from
      the public access network deployed on a bus.

   o  The attaching node is an MR with nodes behind it, i.e., a mobile
      network (see Figure 5).  For instance, when a passenger carrying a
      PAN gets Internet access from the public access network deployed
      on a bus.

   For the second case, we introduce the following terms:

4.1.  Nested Mobile Network (nested-NEMO)

   A mobile network is said to be nested when a mobile network (sub-
   NEMO) is attached to a larger mobile network (parent-NEMO).  The
   aggregated hierarchy of mobile networks becomes a single nested
   mobile network (see Figure 5).

4.2.  Root-NEMO

   The mobile network at the top of the hierarchy connecting the
   aggregated nested mobile networks to the Internet (see Figure 5).





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4.3.  Parent-NEMO

   The upstream mobile network providing Internet access to another
   mobile network further down the hierarchy (see Figure 5).

4.4.  Sub-NEMO

   The downstream mobile network attached to another mobile network up
   in the hierarchy.  It becomes subservient of the parent-NEMO.  The
   sub-NEMO is getting Internet access through the parent-NEMO and does
   not provide Internet access to the parent-NEMO (see Figure 5).

4.5.  Root-MR

   The MR(s) of the root-NEMO used to connect the nested mobile network
   to the fixed Internet (see Figure 5).

4.6.  Parent-MR

   The MR(s) of the parent-NEMO.

4.7.  Sub-MR

   The MR(s) of the sub-NEMO, which is connected to a parent-NEMO

4.8.  Depth

   In a nested NEMO, indicates the number of sub-MRs a packet has to
   cross between a MNN and the root-MR.

   A MNN in the root-NEMO is at depth 1.  If there are multiple root-
   NEMOs, a different depth is computed from each root-MR.

                                               _____
                             _  |        _    |     |
                       _  |-|_|-|  _  |-|_|-|-|     |-|        _
                 _  |-|_|-|  \  |-|_|-|  \  | |_____| |  _  |-|_|
           _  |-|_|-|     |           |     |         |-|_|-|
          |_|-|  \  |                                    \  |
              |

          MNN   AR  sub-MR  AR  root-MR AR              AR   HA

          <--------------><----------><----><---------><-------->
              sub-NEMO     root-NEMO    fl   Internet   Home Network

     Figure 5: Nested Mobility: a sub-NEMO attached to a larger mobile
                                  network



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5.  Multihoming Terms

   Multihoming, as currently defined by the IETF, covers site-
   multihoming [9] and host multihoming.  We enlarge this terminology to
   include "multihomed mobile router" and "multihomed mobile network".
   The specific configurations and issues pertaining to multihomed
   mobile networks are covered in [10].

5.1.  Multihomed Host or MNN

   A host (e.g., an MNN) is multihomed when it has several addresses to
   choose between, i.e., in the following cases when it is:

   o  Multi-prefixed: multiple prefixes are advertised on the link(s) to
      which the host is attached, or

   o  Multi-interfaced: the host has multiple interfaces to choose from,
      on or not on the same link.

5.2.  Multihomed Mobile Router

   From the definition of a multihomed host, it follows that a mobile
   router is multihomed when it has several addresses to choose between,
   i.e., in the following cases when the MR is:

   o  Multi-prefixed: multiple prefixes are advertised on the link(s) to
      which an MR's egress interface is attached, or

   o  Multi-interfaced: the MR has multiple egress interfaces to choose
      between, on or not on the same link (see Figure 6).

                                   _____
                   _           _  |     |
                  |_|-|  _  |-|_|-|     |-|        _
                   _  |-|_|=|  \  |_____| |  _  |-|_|
                  |_|-|     |             |-|_|-|
                                             \  |
                  MNNs   MR   AR  Internet   AR    HA

              Figure 6: Multihoming: MR with multiple E-faces











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5.3.  Multihomed Mobile Network (multihomed-NEMO)

   A mobile network is multihomed when a MR is multihomed or there are
   multiple MRs to choose between (see the corresponding analysis in
   [10]).

                        MR1
                         _  |
                   _  |-|_|-|  _____
                  |_|-|     |-|     |
             MNNs  _  |       |     |-|        _
                  |_|-|  _  |-|_____| |  _  |-|_|
                      |-|_|-|         |-|_|-|
                            |               |
                        MR2

               Figure 7: Multihoming: NEMO with Multiple MRs

5.4.  Nested Multihomed Mobile Network

   A nested mobile network is multihomed when either a root-MR is
   multihomed or there are multiple root-MRs to choose between.

5.5.  Split-NEMO

   Split-NEMO refers to the case where a mobile network becomes two or
   more independent mobile networks due to the separation of Mobile
   Routers that are handling the same MNP (or MNPs) in the original
   mobile network before the separation.

5.6.  Illustration

   Figure 6 and Figure 7 show two examples of multihomed mobile
   networks.  Figure 8 shows two independent mobile networks.  NEMO-1 is
   single-homed to the Internet through MR1.  NEMO-2 is multihomed to
   the Internet through MR2a and MR2b.  Both mobile networks offer
   access to visiting nodes and networks through an AR.

   Let's consider the two following nested scenarios in Figure 8:

   Scenario 1: What happens when MR2a's egress interface is attached to
      AR1?

      *  NEMO-2 becomes subservient to NEMO-1







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      *  NEMO-1 becomes the parent-NEMO to NEMO-2 and the root-NEMO for
         the aggregated nested mobile network

      *  NEMO-2 becomes the sub-NEMO

      *  MR1 is the root-MR for the aggregated nested mobile network

      *  MR2a is a sub-MR in the aggregated nested mobile network

      *  NEMO-2 is still multihomed to the Internet through AR1 and ARz

      *  The aggregated nested mobile network is not multihomed, since
         NEMO-2 cannot be used as a transit network for NEMO-1

   Scenario 2: What happens when MR1's egress interface is attached to
      AR2?

      *  NEMO-1 becomes subservient to NEMO-2

      *  NEMO-1 becomes the sub-NEMO

      *  NEMO-2 becomes the parent_NEMO to NEMO-1 and also the root-NEMO
         for the aggregated nested mobile network

      *  MR2a and MR2b are both root-MRs for the aggregated nested
         mobile network

      *  MR1 is a sub-MR in the aggregated nested mobile network

      *  NEMO-1 is not multihomed

      *  The aggregated nested mobile network is multihomed

                   _  |  _  |
                  |_|-|-|_|-|  _   _____
    NEMO-1    MNNs _  | MR1 |-|_|-|     |
                  |_|-|       ARx |     |-|        _
               AR1 \  |     |  _  |     | |  _  |-|_|
                         _  |-|_|-|     | |-|_|-|
                   _  |-|_|-| ARy |     |       |
                  |_|-| MR2a   _  |     |
    NEMO-2    MNNs _  |     |-|_|-|     |
                  |_|-|  _  | ARz |_____|
                   \  |-|_|-|
               AR2      MR2b

                     Figure 8: Nested Multihomed NEMO




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6.  Home Network Model Terms

   The terms in this section are useful to describe the possible
   configurations of mobile networks at the home.  For a better
   understanding of the definitions, the reader is recommended to read
   [6], where such configurations are detailed.

6.1.  Home Link

   The link attached to the interface at the Home Agent on which the
   Home Prefix is configured.  The interface can be a virtual interface,
   in which case the Home Link is a Virtual Home Link.

6.2.  Home Network

   The Network formed by the application of the Home Prefix to the Home
   Link.  With NEMO, the concept of Home Network is extended as
   explained below.

6.3.  Home Address

   With Mobile IPv6, a Home Address is derived from the Home Network
   prefix.  This is generalized in NEMO with some limitations: A Home
   Address can be derived either from the Home Network or from one of
   the Mobile Router's MNPs.

6.4.  Mobile Home Network

   A Mobile Network (NEMO) that is also a Home Network.  The MR, or one
   of the MR(s), that owns the MNP may act as the Home Agent for the
   mobile nodes in the Mobile Home Network.

6.5.  Distributed Home Network

   A Distributed Home Network is a Home Network that is distributed
   geographically between sites.  The aggregated Home Prefix is
   partitioned between the sites and advertised by all sites.

   This aggregated Home Prefix can be further aggregated within a
   service provider network or between service providers, to form a
   prefix that is announced into the Internet by the service provider(s)
   from multiple points.

   The sites may be connected using a mesh of private links and tunnels.
   A routing protocol is used within and between sites to exchange
   routes to the subnets associated to the sites and, eventually, to
   Mobile Routers registered off-site.




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6.6.  Mobile Aggregated Prefix

   An aggregation of Mobile Network Prefixes.

6.7.  Aggregated Home Network

   The Home Network associated with a Mobile Aggregated Prefix.  This
   aggregation is advertised as a subnet on the Home Link, and thus used
   as the Home Network for NEMO purposes.

6.8.  Extended Home Network

   The network associated with the aggregation of one or more Home
   Network(s) and Mobile Network(s).  As opposed to the Mobile IPv6 Home
   Network that is a subnet, the Extended Home Network is an aggregation
   and is further subnetted.

6.9.  Virtual Home Network

   An aggregation of Mobile Network Prefixes that is in turn advertised
   as the Home Link Prefix.  The Extended Home Network and the
   Aggregated Home Network can be configured as Virtual Home Network.

7.  Mobility Support Terms

7.1.  Host Mobility Support

   Host Mobility Support is a mechanism that maintains session
   continuity between mobile nodes and their correspondents upon the
   mobile host's change of point of attachment.  It can be achieved
   using Mobile IPv6 or other mobility support mechanisms.

7.2.  Network Mobility Support (NEMO Support)

   Network Mobility Support is a mechanism that maintains session
   continuity between mobile network nodes and their correspondents upon
   a mobile router's change of point of attachment.  Solutions for this
   problem are classified into NEMO Basic Support, and NEMO Extended
   Support.

7.3.  NEMO Basic Support

   NEMO Basic Support is a solution to preserve session continuity by
   means of bidirectional tunneling between MRs and their HAs, much like
   what is done with Mobile IPv6 [4] for mobile nodes when Routing
   Optimization is not used.  Only the HA and the MR are NEMO-enabled.
   RFC 3963 [5] is the solution specified by the NEMO Working Group for
   NEMO Basic Support.



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7.4.  NEMO Extended Support

   NEMO Extended support is to provide performance optimizations,
   including routing optimization between arbitrary MNNs and CNs.

7.5.  NEMO Routing Optimization (NEMO RO)

   The term "Route Optimization" is accepted in a broader sense than
   already defined for IPv6 Host Mobility in [4] to loosely refer to any
   approach that optimizes the transmission of packets between a Mobile
   Network Node and a Correspondent Node.

   For more information about NEMO Route Optimization in the NEMO
   context, see the problem statement [7] and the solution space
   analysis [8].

7.6.  MRHA Tunnel

   The bidirectional tunnel between a Mobile Router and its Home Agent.

7.7.  Pinball Route

   A pinball route refers to the non-direct path taken by packets, which
   are routed via one or more Home Agents, as they transit between a
   Mobile Network Node and a Correspondent Node.

   A packet following a pinball route would appear like a ball bouncing
   off one or more Home Agents before reaching its final destination.

8.  Security Considerations

   As this document only provides terminology and describes neither a
   protocol, procedure, or an implementation, there are no security
   considerations associated with it.

9.  Acknowledgments

   The material presented in this document takes most of the text from
   documents initially submitted to the former MobileIP WG and MONET BOF
   and was published as part of a PhD dissertation [11].  The authors
   would therefore like to thank both Motorola Labs Paris and INRIA
   (PLANETE team, Grenoble, France), where this terminology originated,
   for the opportunity to bring it to the IETF, and particularly Claude
   Castelluccia for his advice, suggestions, and direction, Alexandru
   Petrescu and Christophe Janneteau.  We also acknowledge input from
   Erik Nordmark, Hesham Soliman, Mattias Petterson, Marcelo Bagnulo,
   T.J. Kniveton, Masafumi Watari, Chan-Wah Ng, JinHyeock Choi, and
   numerous other people from the NEMO Working Group.  The Home Network



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   Model section is contributed by Pascal Thubert, Ryuji Wakikawa, and
   Vijay Devaparalli.

10.  References

10.1.  Normative References

   [1]   Ernst, T., "Network Mobility (NEMO) Support Goals and
         Requirements", RFC 4886, July 2007.

   [2]   Deering, S. and R. Hinden, "Internet Protocol Version 6
         (IPv6)", RFC 2460, December 1998.

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

   [4]   Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
         IPv6", RFC 3775, June 2004.

   [5]   Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
         "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
         January 2005.

   [6]   Thubert, P., Wakikawa, R., and V. Devarapalli, "Network
         Mobility (NEMO) Home Network Models", RFC 4887, July 2007.

   [7]   Ng, C-W., Thubert, P., Watari, M., and F. Zhao, "Network
         Mobility Route Optimization Problem Statement", RFC 4888,
         July 2007.

   [8]   Ng, C-W., Zhao, F., Watari, M., and P. Thubert, "Network
         Mobility Route Optimization Solution Space Analysis", RFC 4889,
         July 2007.

10.2.  Informative References

   [9]   Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site-
         Multihoming Architectures", RFC 3582, August 2003.

   [10]  Ng, C-W., Paik, E-K., Ernst, T., and M. Bagnulo, "Analysis of
         Multihoming in Network Mobility Support", Work in Progress,
         February 2007.

   [11]  Ernst, T., "Network Mobility Support in IPv6", PhD's Thesis.,
         Universite Joseph Fourier, Grenoble, France , October 2001.






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Authors' Addresses

   Thierry Ernst
   INRIA
   Rocquencourt
   Domaine de Voluceau B.P. 105
   78153 Le Chesnay Cedex,
   France

   Phone: +33 (0)1 39 63 59 30
   Fax:   +33 (0)1 39 63 54 91
   EMail: thierry.ernst@inria.fr
   URI:   http://www-rocq.inria.fr/imara


   Hong-Yon Lach
   Motorola
   Parc les Algorithmes - Saint-Aubin
   911193 Gif-sur-Yvette Cedex,
   France

   Phone: +33 (0)1 69-35-25-36
   EMail: hong-yon.lach@motorola.com




























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