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Versions: 00 01 draft-ernst-nemo-terminology

IETF INTERNET-DRAFT                                        Thierry Ernst
                                                    WIDE Project / INRIA
                                                           Hong-Yon Lach
                                                           Motorola Labs
                                                           February 2002

                  Network Mobility Support Terminology
                  draft-ernst-monet-terminology-00.txt




Status of This Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

Abstract

   The purpose of traditional mobility support is to provide continuous
   Internet connectivity to mobile hosts (host mobility support). In
   contrast, network mobility support is concerned with situations where
   an entire network changes its point of attachment to the Internet and
   thus its reachability in the topology. We shall refer to such a
   network as a mobile network (MONET). There is presently no existing
   terminology to define the issues, goals, architecture elements,
   problems and requirements pertaining to network mobility support, but
   one is needed. It is therefore the object of this document to define
   a new terminology, to depict the characteristics of mobile networks
   and to make some observations.






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                                 Contents

Status of This Memo

Abstract

1. Introduction

2. Terminology
   2.1. Architecture Components
   2.2. Other Terminology

3. Characteristics / Observations

Acknowledgments

References

Author's Addresses

 1. Introduction

   The purpose of traditional mobility support is to provide continuous
   Internet connectivity to mobile hosts (host mobility support). In
   contrast, network mobility support is concerned with situations where
   an entire network changes its point of attachment to the Internet and
   thus its reachability in the topology. We shall refer to such a
   network as a mobile network (MONET).

   Cases of mobile networks include networks attached to people
   (Personal Area Network or PAN, i.e. a network composed by all
   Internet appliances carried by people, like a PDA, a mobile phone, a
   digital camera, a laptop, etc.) and networks of sensors deployed in
   aircrafts, boats, busses, cars, trains, etc. An airline company that
   provides permanent on-board Internet access is an example of a mobile
   network. This allows passengers to use their laptops (this scenario
   is mentioned in [Tanenbaum96] under section 1.2.4 and section 5.5.8;
   [Perkins98] under section 5.12; [Solomon98] under section 11.2; and
   [RFC2002] section 4.5), PDA, or mobile phone to connect to remote
   hosts, download music or video, browse the web. Passengers could
   themselves carry a network with them (a PAN). At the same time, air
   control traffic could be exchanged between the aircraft and air
   traffic control stations (this scenario has already been investigated
   by Eurocontrol, the European Organization for the safety of air
   navigation, [Quinot98]). During a transatlantic flight, the aircraft
   changes its point of attachment to the Internet and may be reachable
   by distinct Internet Service Providers (ISPs). Over the oceans, the
   aircraft gets connected to the Internet through a geostationary



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   satellite; over the ground, it's through a radio link. Handoffs do
   typically not occur very often (a radio link may cover 400-500
   kilometers). Another similar scenario mentioning ships and aircrafts
   can be found in [RFC1726, section 5.15]. Similarly, a bus, the
   metropolitan public transport, or the taxi company could allow
   passengers to connect their PAN to the Internet via the embarked
   network, therefore ensuring, while on-board, an alternative to the
   metropolitan cellular network, in terms of price or available
   bandwidth, access control, etc. Meanwhile, a number of Internet
   appliances deployed in the mobile network are used to collect traffic
   and navigation data from the Internet while sensors within the mobile
   network collect and transmit to the Internet live information, like
   the current number of passengers, expected time to arrival, the
   amount of petrol left in the tank, etc. For a number of reasons
   (network management, security, performance,...), it is desirable to
   interconnect the Internet appliances deployed in cars, trains, busses
   by means of, for instance, an Ethernet cable, instead of connecting
   them individually and directly to the Internet, therefore exhibiting
   the need to displace an entire network.

   To describe such kind of scenarios, we need to agree on a
   terminology.  However, there is presently no existing terminology to
   define the issues, goals, architecture elements, problems and
   requirements pertaining to the scenarios outlined here above, but one
   is needed. It is therefore the object of this document to define such
   a new terminology and to make some observations.  The material
   presented in this document is based on [Ernst01] and on our former
   internet-draft that was submitted in July 2001 [OLD-draft] for the
   consideration of the Mobile IP Working Group. In addition to the
   present terminology, this former draft was also presenting a set of
   requirements and issues as an attempt to clarify the problem caused
   by networks in motion. We decided to split this former document in
   two because requirements are more subject to discussion and
   disagreements that the terminology on which we must agree on to base
   our discussion. Our proposed requirements can therefore now be found
   in [REQUIREMENTS]. Additional requirements may be found in
   [REQUIREMENTS-NOKIA] and [REQUIREMENTS-MOTOROLA]. A comprehensive
   description of the problem and issues posed by networks in motion is
   discussed in [SCOPE]. More information may be found on the MONET web
   page [WEB-MONET].


 2. Terminology

   Our proposed terminology defines a number of new terms in conformance
   with the terminology already defined in the IPv6 [RFC2460] and Mobile
   IPv6 [MIPv6] specifications. Note that our terminology is primarily
   targeted to IPv6, but is not limited to it. The first section defines



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   the architecture components, and the second section defines a number
   of other terms useful to discuss requirements.

  2.1. Architecture Components

   Mobile Network (MONET)

      A set of nodes composed by one or more IP-subnets attached to a
      mobile router (MR) and mobile as a unit, with respect to the rest
      of the Internet, i.e. a MR and all its attached nodes. The MR
      changes dynamically its point of attachment to the Internet and
      thus its reachability in the Internet.

   Mobile IP-subnet

      A MONET composed of a single IP-subnet.
            ____
           |    |
           | CN |
           |____|
          ___|____________________
         |                        |
         |                        |
         |       Internet         |
         |                        |
         |________________________|
            __|_            __|_
           |    |  Access  |    |
           | AR |  Router  | AR |
           |____|          |____|
        ______|__ foreign   __|_____________ home
                  link               __|_    link
                                    |    |
                                    | MR | Mobile Router
                                    |____|
                              _________|_______  internal
                               __|__     __|__   link
                              |     |   |     |
                              | MNN |   | MNN | Mobile Network Nodes
                              |_____|   |_____|

                            Figure 1: Terminology

   Mobile Network Node (MNN)

      Any host or router located within the MONET, either permanently or
      temporarily. A MNN could be any of a MR, LFN, VMN, or LMN. The
      distinction between LFN, LMN and VMN is necessary to discuss



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      issues related to mobility management and access control, but does
      not preclude that mobility should be handled differently.

   Mobile Router (MR)

      A router which attaches the MONET to the rest of the Internet. The
      MR maintains the Internet connectivity for the MONET. It is used
      as a gateway to route packets between the MONET and the Internet.
      The MR has at least two interfaces, an egress interface, and an
      ingress interface. When transmitting a packet to the Internet
      (i.e. outside), it sends it through the egress interface; when
      transmitting it withing the MONET (i.e. inside), it sends it
      through the ingress interface.
                    ____
                   |    |
                   | CN |
                   |____|
                  ___|____________________
                 |                        |
                 |                        |
                 |       Internet         |
                 |                        |
                 |________________________|
                    __|_            __|_
                   |    |  Access  |    |
                   | AR |  Router  | AR |
                   |____|          |____|
                    __|_         _____|_____________ home
                   |    |                     _|__   link
                   | MN ]                 |  |    |
                   |____|                 |__| MR | Mobile Router
                                          |  |____|
                                          |   __|_____________ internal
                                          |   __|__     __|__  link 1
                                  _____   |  |     |   |     |
                                 |     |__|  | LFN |   | LMN |
                                 | LFN |  |  |_____|   |_____|
                                 |_____|  |
                                          | internal
                                            link 2

                Figure 2: Larger Mobile Network with 2 subnets

   Local Fixed Node (LFN)

      A node permanently located within the MONET and that does not
      change its point of attachment. A LFN can either be a LFH (Local
      Fixed Host) or a LFR (Local Fixed Router).



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   Local Mobile Node (LMN)

      A mobile node that belongs to the MONET and that changes its point
      of attachment from a link within the mobile network to another
      link within or outside the MONET (the home link of the LMN is a
      link within MONET). A LMN can either be a LMH (Local Mobile Host)
      or a LMR (Local Mobile Router).

                    ____
                   |    |
                   | CN |
                   |____|
                  ___|____________________
                 |                        |
                 |                        |
                 |       Internet         |
                 |                        |
                 |________________________|
                    __|_            __|_
                   |    |  Access  |    |
                   | AR |  Router  | AR |
                   |____|          |____|
                    __|_         _____|_____________ home
                   |    |                     _|__   link
                   | MN |                 |  |    |
                   |____|         _____   |__| MR | Mobile Router
                                 |     |__|  |____|
                           |-->  | LMN |  |   __|_____________ internal
                           |     |_____|  |   __|__       |     link 1
                           |      _____   |  |     |
                           |     |     |__|  | LFN |
                           |     | LFN |  |  |_____|      |
                           |     |_____|  |               |
                           |              | internal      |
                           |                 link 2       |
                           |------------------------------|

                        Figure 3: LMN changing subnet

   Visiting Mobile Node (VMN)

      A mobile node that does not belong to the MONET and that changes
      its point of attachment from a link outside the MONET to a link
      within the MONET (the home link of the VMN is not a link within
      the MONET). A VMN that attaches to a link within the MONET obtains
      an address on that link. A VMN can either be a VMH (Visiting
      Mobile Host) or a VMR (Visiting Mobile Router).




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   Top-Level Mobile Router (TLMR)

      In case there are more MONETs aggregated into the MONET, the TLMR
      is the MR(s) used to direcly connect the aggregated MONET to the
      fixed Internet.

   Node behind the MR

      Any MNN in a MONET that is not a MR for this MONET.

   Correspondent Node (CN) of a MONET

      Any node located outside the MONET that is communicating with one
      or more MNNs. CNs corresponding with MNNs located in the same
      MONET are said to be CNs of this MONET.

   Access Router (AR)

      Any subsequent point of attachment of the MONET at the network
      layer. Basically, a router on the home link or the foreign link.
      When considering nested mobility, an AR seen by the MONET may be a
      MR or a LFR for the entire network.

   Home subnet prefix

      A bit string that consists of some number of initial bits of an IP
      address which identifies the home link within the Internet
      topology (i.e. the IP subnet prefix corresponding to the mobile
      node's home address, as defined in [MIPv6]).

   Foreign subnet prefix

      A bit string that consists of some number of initial bits of an IP
      address which identifies a foreign link within the Internet
      topology.

   Mobile Network Prefix

      A bit string that consists of some number of initial bits of an IP
      address which identifies a MONET within the Internet topology.
      Nodes belonging to the MONET (i.e. at least MR, LFNs and LMNs)
      share the same IPv6 "network identifier". For a single mobile IP-
      subnet, the Mobile Network Prefix is the "network identifier" of
      this subnet.

   Egress Interface of a MR

      The interface attached to the home link if the MONET is at home,



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      or attached to a foreign link if the MONET is in a foreign
      network.

   Ingress Interface of a MR

      The interface attached to a link inside the MONET. This interface
      is configured with the Mobile Network Prefix.
                    ____
                   |    |
                   | CN |
                   |____|
                  ___|____________________
                 |                        |
                 |                        |
                 |       Internet         |
                 |                        |
                 |________________________|
                    __|_            __|_
                   |    |  Access  |    |
                   | AR |  Router  | AR |
                   |____|          |____|
                                _____|_____________ home
                     |                        _|__   link
                     |                    |  |    |
                     |            _____   |__| MR | Mobile Router
                     |           |     |__|  |____|
                     ----------> | VMN |  |   __|_____________ internal
                                 |_____|  |   __|__     __|__  link 1
                                  _____   |  |     |   |     |
                                 |     |__|  | LFN |   | LMN |
                                 | LFN |  |  |_____|   |_____|
                                 |_____|  |
                                          | internal
                                            link 2

            Figure 4: Nested Mobility: Visiting Mobile  Node (VMN)


   The terminology is summarized in fig.1 and to 5. Fig.1 shows a single
   mobile IP-subnet. Fig.2. shows a large mobile network. Fig.3
   illustrates a LMN changing subnet within the mobile network whereas
   fig.4 illustrates the case of a VMN that enters the mobile network.
   Fig 5. illustrates the case of a mobile IP-subnet that attaches to a
   MONET.

  2.2. Other Terminology

   Nested mobility



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      We speak about nested mobility when a MONET comprises mobile nodes
      (LMNs or VMNs) and even MONETs. In the bus instance, the bus is a
      MONET whereas a passenger is either a VMN in a MONET if it carries
      a mobile phone or a MONET in the MONET if it carries a PAN.
                    ____
                   |    |
                   | CN |
                   |____|
                  ___|____________________
                 |                        |
                 |                        |
                 |       Internet         |
                 |                        |
                 |________________________|
                    __|_            __|_
                   |    |  Access  |    |
                   | AR |  Router  | AR |
                   |____|          |____|
                                _____|_____________ home
                                              _|__   link
                                          |  |    |
                               |  _____   |__| MR | Mobile Router (TLMR)
                               |_|     |__|  |____|
                               | | VMR |  |   __|_____________ internal
                               | |_____|  |   __|__     __|__  link 1
                       _____   |          |  |     |   |     |
                      |     |  |          |  | LFN |   | LMN |
                      | LFN |__|          |  |_____|   |_____|
                      |_____|  |          |
                               |          | internal
                                            link 2

            Figure 5: Nested Mobility: mobile IP-subnet in a MONET

   Multi-Homing

      A MONET is multi-homed when it has two or more active egress
      interfaces connected to distinct parts of the Internet. This could
      either be a single MR with two egress interfaces simultaneously
      connected to the Internet, or the MONET may be connected to the
      Internet via two or more MRs. In the first case, we could think of
      a unique router used to connect a car both to the cellular phone
      network and to a satellite. In the second case, we may think of a
      PAN where a phone is used to connect the PAN to the cellular phone
      network whereas a Bluetooth PDA is used to collect bus timetables
      from the city bus network. In this situation both the phone and
      the PDA are MRs.




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   Local-Area Mobility

      Mobility within a single administrative domain, i.e. between
      subnetworks topologically close in the IP hierarchy. In the
      literature, and depending on the definition of ``closeness'', this
      is also termed intra-site mobility, intra-domain mobility, local
      mobility or micro-mobility. As an instance of Local-Area Mobility,
      the displacement of a node within a limited vicinity of adjacent
      subnetworks, like in a campus, that belong to the same
      organization or between ARs that belong to the same ISP.

   Wide-Area Mobility

      Mobility across domain boundaries, i.e. between subnetworks
      topologically distant in the IP hierarchy. In the literature, and
      depending on the definition of ``remoteness'', this is also termed
      inter-site mobility, inter-domain mobility, or global mobility, or
      macro-mobility. As an instance of Wide-Area Mobility, displacement
      of a node between distinct ISPs or organizations, or between
      widely separated sites of a single organization.

   Idle MNN

      A MNN that does not engage in any communication.

   Idle Mobile Network

      A MONET that does not engage in any communication outside the
      network may be considered as idle from the point of view of the
      Internet. This doesn't preclude that MNNs are themselves idle.
      Internal traffic between any two MNNs located in the same MONET is
      not concerned by this statement.



















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 3. Observations

   Structure of the mobile network

      A MR changing its point of attachment does not cause the MNNs
      behind the MR to change their own physical point of attachment.
      Thus, the internal structure of a MONET is not modified as a
      result of the MONET changing its point of attachment and a MNN may
      not notice such a displacement. However, MNNs MAY appear to move
      from the point of view of an other node in the Internet.

   Mobile Router is a transit point

      All packets sent from a CN to a MNN necessarily transit through a
      MR.

   Size of the MONET

      A MONET may comprise one or more subnets. Its size could scale
      from a sole subnet with a few IP devices, such as in the case of a
      PAN, to a collection of subnets with hundreds of IP devices, such
      as in a train.

   Large number of CNs

      A MONET may have a very large number of CNs.  For instance, each
      passenger in a train may be considered a MNN.  Each of them may be
      communicating with a few CNs. As a result, the total number of CNs
      could be several times as large as the number of MNNs and scale up
      to a few thousands.

   Sparseness of the CNs

      CNs are typically sparsely distributed in the Internet and belong
      to distinct administrative domains.

   Handoff frequency

      MONETs may not move with the same speed and frequency. For
      instance, a PAN connected to the Internet via a 802.11b WLAN (e.g.
      user in a shopping mall) is likely to change its point of
      attachment very frequently, while an aircraft or a boat may be
      connected to the Internet via the same satellite link for a couple
      of hours. Obviously, MONETs may not move at all for a large amount
      of time.

   Ad-Hoc Network




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      An Ad-hoc network as defined in the IETF MANET Working Group is
      not to be confused with a MONET. An ad-hoc network is an
      autonomous system of mobile nodes (i.e. routers) connected by
      wireless links. The routers are free to move randomly and to
      organize themselves arbitrary. In a mobile network, some routers
      may effectively move arbitrary, but this not a common case.
      However, an Ad-hoc network connected to the Internet and that
      changes its point of attachment may be considered as a special
      instance of a MONET.

   Routers in the Mobile Network

      All routers in the Internet are considered to run a number of
      protocols such as a routing protocol, Neighbor Discovery, ICMP,
      and others. This also applies to routers in the MONET, including
      the MR.



































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Acknowledgments

   The first author would like to thank both Motorola Labs Paris and
   INRIA Rhône-Alpes, for the opportunity to bring this topic to the
   IETF, and particularly Claude Castelluccia (INRIA) for its advices,
   suggestions, and direction. We also acknowledge Alexandru Petrescu
   (Motorola), Christophe Janneteau (Motorola), Hesham Soliman
   (Ericsson) and Mattias Petterson (Ericsson) for their comments on
   this draft.

References

   [Ernst01] Thierry Ernst "Network Mobility Support in IPv6", PhD
   Thesis, University Joseph Fourier Grenoble, France. October 2001.

   [MIPv6] David B. Johnson and C. Perkins. "Mobility Support in IPv6".
   Internet Draft draft-ietf-mobileip-ipv6-14.txt, Internet Engineering
   Task Force (IETF), July 2001. Work in progress.

   [OLD-draft] Thierry Ernst, Hong-Yon Lach, Claude Castelluccia
   "Network Mobility Support in IPv6: Problem Statement and
   Requirements", IETF Internet-Draft draft-ernst-mobileip-
   monetv6-00.txt, July 2001. Expiration pending.

   [Perkins98] C. E. Perkins. Mobile IP, Design Principles and
   Practices. Wireless Communications Series. Addison-Wesley, 1998. ISBN
   0-201-63469-4.

   [Quinot98] Thomas Quinot. An IPv6 architecture for Aeronautical
   Telecommunication Network. Master's thesis, Ecole Nationale
   Superieure des Telecommunications Paris, EUROCONTROL - European
   Organization for the Safety of Air Navigation - ISA project (IPv6,
   Satellite communication and ATMode for ATN), 1998.
   http://www.eurocontrol.fr/.

   [RFC1726] C. Partridge "Technical Criteria for Choosing IP the Next
   Generation (IPng)", IETF RFC 1726 section 5.15, December 1994.

   [RFC2460] S. Deering and R. Hinden. "Internet Protocol Version 6
   (IPv6) Specification".  IETF RFC 2460, Internet Engineering Task
   Force (IETF), December 1998.

   [RFC2002] C. Perkins (Editor). IP Mobility Support. IETF RFC 2002,
   October 1996.

   [REQUIREMENTS] Thierry Ernst "Requirements for Network Mobility
   Support", IETF Internet-Draft draft-ernst-monet-requirements-00.txt,
   February 2001. Work in progress.



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   [REQUIREMENTS-MOTOROLA] Hong-Yon Lach "Mobile Network Scenarios,
   Scope and Requirements", IETF Internet-Draft draft-lach-monet-
   requirements-00.txt, February 2002. Work in progress.

   [REQUIREMENTS-NOKIA] draft-kniveton-monet-requirements.txt, February
   2002. Work in progress.

   [SCOPE] Hesham Soliman "Problem Scope", IETF Internet-Draft draft-
   soliman-monet-scope-00.txt, February 2002. Work in progress.

   [Solomon98] J. D. Solomon. Mobile IP, The Internet Unplugged.
   Prentice Hall Series in Computer Networking and Distributed Systems.
   Prentice Hall PTR, 1998. ISBN 0-13-856246-6.

   [Tanenbaum96] Andrew Tanenbaum "Computer Networks", Prentice-Hall,
   Third Edition. 1996

   [WEB-MONET] MONET web page http://www.nal.motlabs.com/monet


Author's Addresses

    Questions about this document can be directed to the authors:


      Thierry Ernst,
      WIDE Project
      Jun Murai lab. Faculty of Environmental Information,
      Keio University.
      5322 Endo, Fujisawa-shi, Kanagawa 252-8520, Japan.
      Phone : +81-466-49-1100
      Fax   : +81-466-49-1395
      E-mail: ernst@sfc.wide.ad.jp
      Web: http://www.sfc.wide.ad.jp/~ernst/

      Hong-Yon Lach
      Motorola Labs Paris, Lab Manager,
      Networking and Applications Lab (NAL)
      Espace Technologique - Saint Aubin
      91193 Gif-sur-Yvette Cedex, France
      Phone: +33-169-35-25-36
      Email: Hong-Yon.Lach@crm.mot.com









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