Mobile IP Working Group                       Claude Castelluccia
INTERNET-DRAFT                                Lubovic Bellier
                                              INRIA, FRANCE
                                              25 June 1999




      Toward a Unified Hierarchical Mobility Management Framework
                draft-castelluccia-uhmm-framework-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
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   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

   As the number of Mobile Nodes increases in the Internet, it becomes
   clear that a hierarchical mobility management protocol is necessary.
   The macro-mobility is the mobility between domains.  The micro-
   mobility is the mobility within one domain.  Several proposals that
   separate macro and micro-mobility has been proposed recently
   (CellularIP[4], HAWAI[3], HMIP[1],...).

   All these proposals agree that Mobile IP is suitable to handle
   macro-mobility (inter-domain mobility) but they all propose a
   different micro-mobility scheme. As a result, a Mobile Node won't be
   able to roam seamlessly if it does not understand the different



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   micro-mobility management protocols of the domain that it visits.

   In this document, we present a framework that allows the deployment
   of various micro-mobility management protocols in different parts of
   the Internet while still providing connectivity to Mobile Nodes.

   We propose to decompose the Internet mobility management protocol
   into three components. The first one, the access protocol, specifies
   the registration procedures between the Mobile Node and the domain it
   is attached to. It is standard and unique. The second one, the
   micro-mobility protocol, manages local mobility and varies from one
   domain to another. The third one, the macro-mobility protocol,
   manages mobility across domains.  We suggest to use Mobile IP as the
   macro-mobility protocol.

   This Internet Draft first describes the architecture of the proposed
   framework. It then show how micro-Mobile IP and Cellular IP could be
   deployed within this framework.



1- Introduction

   There have been several hierarchical and cellular Mobile IP proposals
   recently. This shows a huge interest for a scalable mobility
   management scheme.  There are at least 3 proposals that we know of :
   - Ericsson/Columbia Cellular IP [4]
   (http://comet.ctr.columbia.edu/cellularip/)
   - Lucent HAWAII [3] (http://www.bell-
   labs.com/user/ramjee/papers/draft-ramjee-micro-mobility-hawaii-
   00.txt)
   - INRIA HMIPv6 [1]
   (http://sirac.inrialpes.fr/Infos/Personnes/Claude.Castelluccia/hmip.ps.gz)

   All these proposals agree that Mobile IP is suitable to handle
   macro-mobility, but they all propose a different micro-mobility
   scheme.

   From then, 2 directions are possible :

      1- define a single micro-mobility protocol is defined and
      standardized from the existing and forthcoming proposals.

      2- define a framework that allows each proposal to be deployed and
      that provides inter-operability is defined.

   We argue that the second solution is preferable for the following
   reasons. First we believe that there is probably not an "optimal"



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   micro-mobility scheme for every network. Different protocols might be
   necessary for different networks' needs.  Second, defining an open
   system leads to more competition and flexibility.  Each network
   operator is then free to deploy its own micro-mobility protocol (and
   to patent it:-)). New protocols can be deployed very easily.  Last
   but not least it eases drastically the standardization process ; the
   different proposals do not have to be merged into a single one.

   In this document, we propose a framework that allows the deployment
   of different micro-mobility proposals. We assume that Mobile IP is
   used as the macro-mobility protocol.

   Our final goal is to define a framework that allows a Mobile Node to
   roam seamlessly from one network to another, from one domain to
   another... One condition to achieve this goal is to make sure  that
   the mobility management procedures performed by the Mobile Nodes are
   independent of the  mobility management protocols used in the core of
   the network.

2- General concepts

   In this document, we define a domain as an arbitrary structure. A
   domain can be an ISP network, a campus network, a company network, a
   set of LANs or even a single LAN. A domain is connected to the rest
   of the Internet via one or several interconnection routers that we
   call Border Routers in this document.

   Our proposal differentiates the macro (inter-domain) mobility from
   the micro (intra-domain) mobility. As a result, a host communicating
   with a Mobile Node is only aware of its inter-domain mobility. The
   Mobile Node's intra-domain mobility is completely hidden. It also
   defines a standard Mobile Node registration protocol that is
   independent of the mobility management protocols used in the core
   network. As a result, different mobility management protocols can be
   used in the different parts of the Internet while still providing
   connectivity to the Mobile Node Hosts.

   We propose a mobility management framework that uses Mobile IP for
   inter-domain mobility but allows the deployment of any micro-mobility
   protocol. As a matter a result, different domains can deploy
   different micro-mobility protocols.

 2.1 Design Goals/Constraints

   The goals of our work is to propose a hierarchical mobility
   management that :

      1- does not require any modifications at the Correspondent Nodes



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      (Correspondent Nodes are running Mobile IP).
      2- allows the deployment of different micro-mobility schemes
      transparently to the Correspondent Nodes and the Mobile Nodes.
      3- does not degrade routing performance.
      4- is as secure as Mobile IP.
      6- works in IPv4 and IPv6.
      7- is power-efficient (i.e. minimizes the power).

 2.2 Conceptual Model

   In the proposed framework, the mobility management protocol is
   composed of three components as illustrated in Figure 1.

      - The first one, the access mobility management protocol,
      specifies the registration procedures between the Mobile Node and
      the domain it is attached to. It is standard and independent of
      the micro and macro-mobility management protocols used in the core
      of the network. This protocol is  ``light'', i.e.  minimises the
      operations performed by the Mobile Node Hosts (which probably have
      limited capacity and power).

      - The second one, the micro-mobility management protocol, is the
      protocol that handles the local mobility (within the domain) of
      the Mobile Node.

      - The third one, the macro-mobility management protocol, is the
      protocol that handles the macro-mobility (inter-domain) of the
      Mobile Node.  We propose to use Mobile IP as macro-mobility
      management protocol.

3- Proposed Framework

 3.1 Overview

      Our proposal is based on the deployment of Mobility Supports.

      A Mobility Support is a router or a set of routers  that maintains
      a binding per Mobile Nodes currently visiting the domain. The
      Mobility Support plays a central role in our proposal. It is
      involved in the macro and micro-mobility management. For example,
      the Mobility Support sends Binding Updates on behalf of the Mobile
      Nodes it is serving (macro-mobility management). It also
      intercepts packets addressed to the Mobile Nodes it is serving and
      is in charge of redirecting them to their current location
      (micro-mobility management).

      Note that there is no constraint on the physical location of the
      Mobility Support. However for efficiency reasons, it is



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      preferable to connect it as close as possible to the border router
      of the network that it is serving.

      In our proposal, the Mobile Node registration protocol is unique
      and independent of the micro-mobility management protocol of the
      domain.  The nature and the position of the Mobility Support
      depend on the micro-mobility management protocol. The only
      requirements that we impose on the Mobility Support are :

      (1) it must process registration messages coming from the Mobile
      Nodes (the processing depends of the micro-mobility protocols),

      (2) it must send Mobile IP Binding Updates to the Mobile Node's
      Home Agent and Correspondent Nodes (according to the Mobile Node
      IP specification) and

      (3) it must intercept and redirect the packets addressed to the
      Mobile Nodes (the way packets are forwarded to the Mobile Node
      Hosts depends of the local micro-mobility protocol.


             _____Domain________         ____Internet______     __
            /                   \        /                  \--|HA|
 -------    | Mobility Support  |  ___  |                   |   --
|Mobile |---|          O        |_|BR |_|                   |
 -------    |          |        |  ---  |                   |   __
      |     \__________|_______/         \__________________/--|CH|
      |                |                                        --
      |===============>|<===========================================>
       access protocol            macro-mobility:Mobile IP


                            Figure1 : Registration


             _____Domain_______           ____Internet______    __
            /                  \         /                  \--|HA|
 -------    | Mobility Support  |  ___  |                   |  --
|Mobile |---|          O        |_|BR |_|                   |
 -------    |          |        |  ---  |                   |   __
      |     \__________|________/        \___________________/--|CH|
      |                |                                        --
      |<============== |<========================================
       micro-mobility             macro-mobility:Mobile IP


                              Figure2 : Packet delivery




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   In summary,
   1- the protocol between the Mobile Node and the Mobility Support is
   unique
   2- the intra-domain mobility management and routing is managed by the
   local micro-mobility management protocol
   3- the inter-domain mobility and routing is managed by Mobile IP

 3.2 Main operations

      The main operations of the proposed architecture are the following
      :

  3.2.1 Common operations : the Mobile Node-Mobility Support
      registration

         When the Mobile Node detects a new Base Station, it gets a CoA
         (we call it PCoA, for Physical Care-of Address) and registers
         to the Mobility Support. This registration is performed by
         sending a (Home Address, Home Agent, PCoA, MS_p), where MS_p is
         the Mobility Support of the Mobile Node in the previous domain.
         This registration is acknowledged by the Mobility Support.

         This registration phase is independent of the type of movement
         (inter or intra-domain).

  3.2.2 Inter-domain movement

         When a Mobile Node moves into a new domain, it registers to the
         new Mobility Support and the Mobility Support performs the
         following registration operations :

   3.2.2.1 Macro-mobility registration :

         Upon reception of a registration message from a Mobile Node,
         the Mobility Support must :

            * get a  VCoA (Virtual CoA-this could be the Mobility
            Support's address or an address on its subnet) for the
            Mobile Node and registers it to its Home Agent on behalf of
            the Mobile Node. This Binding Update must be acknowledged.
            This acknowledgement is forwarded to the Mobile Node.

            * acknowledge the reception of the Mobile Node-Mobility
            Support registration message to the Mobile Node (this
            acknowlegement contains the VCoA).

            * ask the previous Mobility Support (the Mobility Support of
            the previous domain. We note it MS_p) to redirect all



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            packets addressed to the Mobile Node to it. MS_p must
            acknowledge this request and send the list of current
            Correspondent Nodes and the list of the sequence numbers of
            the latest Binding Updates sent.

            * create a entry that contains the binding between the
            Mobile Node's Home address, its home agent and its VCoA +
            list of (Correspondent Nodes, Sequence Numbers).

            * send a (Home Address, VCoA) Binding Update to each
            Correspondent Node.

         Note : a Mobile Node must receive two ackowledgements after an
         inter-domain movement : one from its Home Agent and one from
         its current Mobility Support otherwise it must assume that the
         registration has failed.

         Upon reception of packets coming from the Home Agent or from
         the previous Mobility Support, the new Mobility Support sends
         Binding Updates to the Mobile Node's Correspondent Nodes. These
         Binding Updates contain the Mobile Node's PCoA if the
         Correspondent Node is local (i.e. within the visiting domain)
         or the Mobile Node's VCoA if the Correspondent Node is distant
         (outside the visiting domain).

         3.2.2.2 Micro-mobility registration :

         Upon reception of a registration message from a Mobile Node,
         the Mobility Support must :

            * create a entry that contains the binding between the
            Mobile Node's PCoA and VCoA. This information is used by the
            Mobility Support to redirect the packets addressed to the
            Mobile Node (VCoA) to its current point of attachment
            (PCoA).

3.2.3 Intra-domain movement :

      When a Mobile Node moves within a domain (i.e it changes of Base
      Station and/or subnet), the Mobile Node registers its new point of
      attachement to the Mobility Support. The Mobility Support then
      performs the following operations :

         - macro-mobility registration

            * no operation is required.

         - micro-mobility registration



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         Upon reception of a registration message from the Mobile Node,
         the Mobility Support :

            * updates the corresponding entry in its cache,

            * possibly sends Binding Updates to the Mobile Node's local
            Correspondent Nodes.

      Note that authentication is only necessary between the Mobile Node
      and the Mobility Support, the Mobility Support and the Home Agent,
      successive Mobility Supports, the Mobility Support and the
      Correspondent Nodes. The Base Stations are just relays and
      therefore do not need to be authenticated.

      The Mobile Node must periodically send registration messages to
      the Mobility Support to refresh its cache's entry. Identically the
      Mobility Support must refresh the Mobile Node's VCoA to its Home
      Agent and Correspondent Nodes by sending Binding Updates.
      Note that the two refresh periods must not have the same value.

 3.3 Packet delivery

      When a (external) Correspondent Node first sends packets to a
      Mobile Node, these packets are addressed to the Mobile Node's Home
      address. These packets are intercepted by the Mobile Node's Home
      Agent (if the Mobile Node is away) and forwarded (by
      encapsulation) to the Mobile Node's current VCoA. The encapsulated
      packets are intercepted by the Mobile Node's current Mobility
      Support and forwarded to the current Mobile Node's PCoA. The
      Mobility Support also sends a (Home Address, PCoA) or a (Home
      Address, VCoA) Binding Update to the Correspondent Node according
      to whether it is local or distant, and records the Correspondent
      Node in its Mobile Node's list of Correspondent Nodes.

      Upon reception of this Binding Update, the Correspondent Node
      updates the Mobile Node's (Home Address, CoA) entry and sends the
      forthcoming packets to the Mobile Node's new CoA. If the CoA is a
      VCoA, the packets are intercepted by the Mobile Node's Mobility
      Support and forwarded to the Mobile Node current PCoA. If the CoA
      is a PCoA, the packets are routed directly to the Mobile Node's
      current location.

      Note that the forwarding method from the Mobility Support to the
      Mobile Node's current PCoA is dependent of the micro-mobility
       used in the domain.

      When a Mobile Node sends a packet to a Correspondent Node, it must
      include a HomeAddress option and use its VCoA as source address



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      (except if the Correspondent Node is local. In this case, it uses
      its PCoA).

4 Examples

   In this section, we describe in more details the architecture and
   operations that are performed with different micro-mobility
   management protocols. We consider two micro-mobility management
   protocols namely micro-Mobile IP and Cellular IP.

 4.1 Mobile Node - Mobility Support registrations

      This phase is common to all micro-mobility proposals.

      When the Mobile Node detects a Base Station, it possibly gets a
      CoA  (we call it, PCoA, for Physical Care-of Address) and
      registers to the Mobility Server. This registration is performed
      by sending a (Home address, Home Agent, PCoA, MS_p), where MS_p is
      the previous Mobility Support of the Mobile Node. If the Mobile
      Node did not change of Mobility Support, the MS_p field is then
      set to Mobility Support.

      The serving Mobility Support and the CoA is obtained via some kind
      of DHCP server or auto-configuration mechanisms. Note also that
      the Mobile Node's operations are independent of the mobility type
      (whether is intra or inter-domain).

      This registration must be acknowledged.

 4.2 Micro-Mobile IP (uMIP)

      The INRIA micro-Mobile IPv6 (uMIP) proposal [Cast98] is based on
      the deployment of Mobility Networks.. A Mobile Network of a domain
      is a LAN that defines an address space for the Mobile Nodes
      roaming within this domain. A Mobility Network contains one or
      several Mobility Supports.  In uMIP, the Mobility Supports are
      called Mobility Agents.  A Mobility Agent is a router of the
      Mobile Network that maintains a binding per Mobile Node currently
      visiting the domain and sends Binding Updates on behalf of these
      Mobile Nodes. Note that there is no constraint on the physical
      location of the Mobility Network. However for efficiency reasons,
      it is  preferable to connect it to the border router of the
      network that it is serving. The mobility Network can actually be
      any sub-network of the domain. It does not have to be dedicated to
      Mobile Nodes but instead can support ordinary (fixed) hosts.

      Deploying a Mobility Agent in a separate Mobility Network instead
      of implementing it on the Border Router has two main advantages.



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      First, it does not require any modification to the routers and is
      therefore easier to deploy. Second, it is more scalable since (1)
      it does not add additional processing constraints on the Border
      Router and (2) several Mobility Agents could be deployed for
      scalability and/or robustness motivations. However the Mobility
      Agent can be implemented within the Border Router if this is
      desirable.

      The main operations of the uMIP proposal are the following.

  4.2.1 Inter-domain mobility

         When a Mobile Node moves into a new domain, the following
         registrations are performed :

         - Mobile Node - Mobile Support registration:

         The Mobile Node registers to the Mobility Agent as described in
         section 4.1.

         - micro-mobility registration operations :  Upon reception of a
         registration message from a Mobile Node, the Mobility Agent :

            o creates an entry that contains the binding between the
            Mobile Node's PCoA and VCoA. This information is used by the
            Mobility Agent to redirect the packets addressed to the
            Mobile Node (VCoA) to its current point of attachment
            (PCoA).

            o sends a (Home Address, PCoA) to the domain's Correspondent
            Nodes to optimize the Correspondent Node-Mobile Node
            routing.

         - macro-mobility registration operations (these operations is
         actually independent of the micro-mobility protocol in used):

         Upon reception of the Mobile Node-Mobility Support registration
         message, the Mobility Agent :

            * gets a  VCoA (an address belonging to the Mobile Network)
            for the Mobile Node and registers it to its Home Agent on
            behalf of the Mobile Node. This Binding Update is
            acknowledged by the Home Agent and forwarded to the Mobile
            Node.

            * acknowledges the reception of the Mobile Node-Mobility
            Support registration message to the Mobile Node (this
            acknowlegement contains the VCoA).



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            * asks the previous Mobility Agent to redirect all packets
            addressed to the Mobile Node to it. The Previous Mobility
            Agent acknowledges this request and sends the list of
            current Correspondent Nodes and the sequence numbers of the
            latest Binding Updates that were sent.

            * creates an entry that contains the binding between the
            Mobile Node's Home address, its home agent and its VCoA +
            list of (Correspondent Nodes, Sequence numbers).

            * sends a (Home Address, VCoA) Binding Update to each
            Correspondent Node.


  4.2.2 Intra-domain mobility :

         When a Mobile Node moves within a domain (i.e it changes of
         Base Station and/or subnet), the following registrations are
         performed :

         - Mobile Node-Mobility Support registration : see Section 4.1.

         - macro-mobility :

           * nothing is sent except the periodic registration refresh
           messages.

         - micro-mobility registration :

           * The Mobility Agent updates the Mobile Node entry of its
           cache.

           * The Mobility Agent sends a (Home Address, PCoA) Binding
           Update to each of the Mobile Node's local Correspondent
           Nodes.


  4.2.3 Packet delivery

         When a (external) Correspondent Node first sends packets to a
         Mobile Node, these packets are addressed to the Mobile Node's
         Home address. These packets are intercepted by the Mobile
         Node's Home Agent (if the Mobile Node is away) and forwarded
         (by encapsulation) to the Mobile Node's current VCoA. The
         encapsulated packets are intercepted by the Mobile Node's
         current Mobility Agent and forwarded (via encapsulation) to the
         current Mobile Node's PCoA. The Mobility Agent adds an entry in
         its cache and sends a (Home Address, PCoA) or a (Home Address,



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         VCoA) Binding Update to the Correspondent Node according
         whether it is local or distant.

         Upon reception of this Binding Update, the Correspondent Node
         updates the Mobile Node's binding(Home Address, CoA) entry and
         sends the forthcoming packets to the Mobile Node's current
         position. If the CoA is the Mobility Agent's address, the
         packets are intercepted by the Mobility Agent and forwarded  to
         the Mobile Node current PCoA (via encapsultion). If the CoA is
         a PCoA, the packets is routed directly to the Mobile Node's
         current location...

 4.3 Cellular IP

      When Cellular IP is used as micro-mobility protocol, the Mobility
      Support is located within the Border Router of the domain. The
      VCoA assigned to the Mobile Nodes is the address of the Mobility
      Support/Border Router.

      The main operations of the proposed architecture are the following
      :

  4.3.1 Inter-domain movement

         When a Mobile Node moves into a new domain, the following
         registrations are performed :

         - Mobile Node-Mobility Support registration :

         The Mobile Node sends a registration message to the Mobility
         Support (Border Router) as specified in 4.1.

         - micro-mobility registration :

         This registration message is intercepted by the Base Station,
         the Mobile Node is attached to. The Base Station encapsulates
         the message within a Route-Update packet as described in
         [CellIP] and forwards it to the Border Router/Mobility Support.
         The Route-Update packet creates and updates entries in each
         node's cache from the Mobile Node to the Mobility Support.

         This registration is acknowledged. (The current Mobility
         Support is broadcast by the base stations using a router
         advertissement).

         - macro-mobility registration :

         Upon reception of the Mobile Node-Mobility Support registration



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         message, the Mobility Support/Border Router :

            * registers the Mobile Node to its Home Agent using its
            address (the Mobility Support's address). This is performed
            by sending a (Home Address, Mobility Support) Binding
            Update. This Binding Update is acknowledged. The
            acknowledgement is forwarded back to the Mobile Node's PCoA
            (via the Cellular IP routing process).

            * acknowledges the reception of the Mobile Node-Mobility
            Support registration message to the Mobile Node (this
            acknowlegement contains the VCoA).

            * asks the previous Mobility Support (the Mobility Support
            of the previous domain. We note it MS_p) to redirect all
            packets addressed to the Mobile Node to it. MS_p
            acknowledges this request and sends the list of current
            Correspondent Nodes and the sequence numbers of the lattest
            Binding Updates that were sent.

            * creates a entry that contains the binding between the
            Mobile Node's Home address, its home agent and its VCoA +
            list of (Correspondent Nodes, Sequence Number).

            * sends a (Home Address, VCoA) Binding Update to each
            Correspondent Node. These Binding Updates contain the Mobile
            Node's PCoA if the Correspondent Node is local (i.e. within
            the visiting domain) or the Mobility Support/Border Router's
            address if the Correspondent Node is distant (outside the
            visiting domain).

  4.3.2 Intra-domain movement :

         When a Mobile Node moves within a domain (i.e it changes of
         Base Station and/or subnet), the following registrations are
         performed :


         - Mobile Node-Mobility Support registration :

         The Mobile Node sends a registration message to the Mobility
         Support (Border Router) as specified in 4.1.

         - micro-mobility

         This registration message is intercepted by the Base Station,
         the Mobile Node is attached to. The Base Station encapsulates
         the message within a Route-Update packet as described in



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         [CellIP] and forwards it to the Border Router/Mobility Support.

         The Route-Update packet creates and updates entries in each
         node's cache from the Mobile Node to the Mobility Support.

         - macro-mobility

         No macro-mobility registration is necessary....besides the
         regular Binding Update refresh Binding Update messages.

  4.3.3 Packet delivery

         When a (external) Correspondent Node first sends packets to a
         Mobile Node, these packets are addressed to the Mobile Node's
         Home address. These packets are intercepted by the Mobile
         Node's Home Agent (if the Mobile Node is away) and forwarded
         (by encapsulation) to the Mobile Node's current Mobility
         Support/Border Router. The encapsulated packets are received by
         the Mobile Node's current Mobility Support/Border Router,
         decapsulated and forwarded (via the CellularIP routing
         mechanisms) to the current Mobile Node's PCoA. The Mobility
         Support/Border Router also sends a (Home Address, Border
         Router) to the external Correspondent Nodes.

         Upon reception of this Binding Update, the Correspondent Node
         updates the Mobile Node's (Home Address, CoA) entry and sends
         the forthcoming packets to the Mobile Node's current Mobility
         Support. The packets are received by the Mobility Support, and
         forwarded to the Mobile Node current PCoA.

5. Security Considerations

   As in Mobile Node IP, all registration messages have to be
   authenticated. As in Mobile Node IP, we propose to use IPSEC to
   authenticate the registration messages and the binding updates.

   There is two levels of security :
      - The macro-mobility registration messages must be authenticated
      between the Mobility Support and the Correspondent Nodes.
      - The micro-mobility registration messages must be authenticated
      between the Mobility Support and the Mobile Nodes.

      Our proposal does not introduce more security problems that those
      introduced by Mobile IP.

6. Conlusion

   We propose a framework that allows the deployment of various micro-



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   mobility management protocols in different parts of the Internet
   while still providing connectivity to Mobile Nodes.

   In the proposed framework, the mobility management protocol is
   composed of 3 components:

      - The first one, the access mobility management protocol,
      specifies the registration procedure between the Mobile Node and
      the domain it is attached to. It is standard and independent of
      the micro and macro-mobility management protocols used in the core
      of the network. This protocol is  ``light'', i.e.  minimises the
      operations performed by the Mobile Nodes (which probably have
      limited capacity and power).

      - The second one, the micro-mobility management protocol, is the
      protocol that handles the local mobility (within the domain) of
      the Mobile Node.

      - The third one, the macro-mobility management protocol, is the
      protocol that handles the macro-mobility (inter-domain) of the
      Mobile Node.  We propose to use Mobile IP as macro-mobility
      management protocol.

   The complete specification of these different components are on its
   way and will be published soon. The access protocol uses Mobile IPv6
   registration messages.



7. Acknowledgments

      We would like to thank Imad Aad, Patrick Cipiere, Jean Michel
   Combe, Walid Dabbous, Thomas Eklund, Thierry Ernst, Patrice Romand
   and Aime LeRouzic for their valuable comments on this draft.

8.  References

   [1] Castelluccia C., "An Hierarchical Mobile IPv6 Proposal", INRIA
   TR-0226, November 1998. Available at
   http://www.inrialpes.fr/Planete/people/ccastel/index.html

   [2] Perkins, C., Editor: "IP Mobility Support", RFC 2002, October
   1996.

   [3]  R. Ramjee, T. La Porta, S. Thuel and K. Varadhan: "IP micro-
   mobility support using HAWAII", draft-ramjee-micro-mobility-hawaii-
   00.txt, 19 February 1999.  Work in progress.




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   [4] Valko, A., Campbell, A. and Gomez, J.: "Cellular IP", Internet
   draft, draft-valko-cellularip-00.txt, November 1998. Work in
   progress.

Author's Address

   Claude Castelluccia and Ludovic Bellier
   INRIA
   PLANETE team
   ZIRST-655 avenue de l'Europe
   38330 Montbonnot Saint Martin
   FRANCE

   Claude.Castelluccia@inria.fr
   Ludovic.Bellier@inria.fr

   draft-castelluccia-uhmm-framework-00.txt


































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