One document matched: draft-ohba-mip6-boot-arch-dhcp-00.txt


MIP6 Working Group                                               Y. Ohba
Internet-Draft                                                      TARI
Expires: April 17, 2005                                         R. Lopez
                                                         Univ. of Murcia
                                                             M. Yanagiya
                                                              H. Ohnishi
                                                                     NTT
                                                            K. Chowdhury
                                                         Nortel Networks
                                                        October 17, 2004


           Mobile IPv6 Bootstrapping Architecture Using DHCP
                   draft-ohba-mip6-boot-arch-dhcp-00

Status of this Memo

   By submitting this Internet-Draft, I certify that any applicable
   patent or other IPR claims of which I am aware have been disclosed,
   and any of which I become aware will be disclosed, in accordance with
   RFC 3668.

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   This Internet-Draft will expire on April 17, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   A mobile node needs home address, home agent address and security
   association with home agent to register with the home agent.  The
   process of obtaining this information is called bootstrapping.  This



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   document describes a bootstrapping architecture in which there is
   some dependency between AAA for network access and AAA for mobility
   service and DHCP in the visited network is used for carrying Mobile
   IPv6 bootstrap information to the mobile node.  The architecture is
   based on an assumption that the mobile node uses network access
   credentials as the seed information without a need to pre-configure
   any Mobile IPv6 service parameters.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Basic Architecture . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Model 1: NAS as a AAA Client for Mobility Service  . . . . . .  6
     3.1   Integrated ASP Scenario  . . . . . . . . . . . . . . . . .  9
     3.2   Third Party MSP Scenario . . . . . . . . . . . . . . . . . 10
   4.  Model 2: NAS as a AAA Client for MIP6 Service  . . . . . . . . 12
     4.1   Integrated ASP Scenario  . . . . . . . . . . . . . . . . . 13
     4.2   Third Party MSP Scenario . . . . . . . . . . . . . . . . . 14
   5.  Comparison with Other Bootstrapping Architectures  . . . . . . 15
     5.1   Home Agent as NAS for AAA for Mobility Service . . . . . . 15
     5.2   MIPv6 Authorization and Configuration based on EAP . . . . 15
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   7.  Open Issues  . . . . . . . . . . . . . . . . . . . . . . . . . 17
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   8.1   Normative References . . . . . . . . . . . . . . . . . . . . 18
   8.2   Informative References . . . . . . . . . . . . . . . . . . . 18
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 19
       Intellectual Property and Copyright Statements . . . . . . . . 20























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1.  Introduction

   A mobile node needs home address, home agent address and security
   association with home agent to register with the home agent.  The
   process of obtaining this information is called bootstrapping
   [I-D.ietf-mip6-bootstrap-ps].  Two minimal sets of parameters or seed
   information with which the mobile node is expected to configure prior
   to bootstrap the rest of the parameters as well as possible
   deployment scenarios where bootstrapping deems necessary are also
   defined in [I-D.ietf-mip6-bootstrap-ps].

   It is important for a bootstrapping architecture to be integrated
   with AAA (Authentication, Authorization and Accounting)
   infrastructure considering large-scale deployment where operators
   rely on a AAA protocol such as RADIUS for providing authentication,
   authorization and accounting functionalities for their subscribers of
   services.  Such services include network access and mobility service.

   This document describes a bootstrapping architecture in which there
   is some dependency between AAA for network access and AAA for
   mobility service and DHCP in the visited network is used for carrying
   Mobile IPv6 bootstrap information to the mobile node.  The
   architecture is based on an assumption that the mobile node uses
   network access credentials as the seed information without a need to
   pre-configure any Mobile IPv6 service parameters.  This document also
   discusses how the proposed architecture is mapped to several
   deployment scenarios described in [I-D.ietf-mip6-bootstrap-ps].  The
   deployment scenarios discussed in this document are integrated ASP
   network scenario and third party MSP scenario.  Other deployment
   scenarios, namely mobility service subscription scenario and
   infrastructure-less scenario, are not discussed in this document
   since it appears that those scenarios are used when AAA for mobility
   service is independent of AAA for network access.

   There are two other bootstrapping architectures that are developed
   based on different assumptions.  One architecture is defined for the
   case where the mobile node is aware of its home agent address
   [I-D.yegin-mip6-aaa-fwk] by some means.  Another architecture is
   based on an assumption that there is some dependency between AAA for
   network access and AAA for mobility service and EAP [RFC3748] is used
   for carrying Mobile IPv6 bootstrap information to the mobile node
   [I-D.giaretta-mip6-authorization-eap].  Comparison with those two
   bootstrapping architectures is also provided in this document.








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2.  Basic Architecture

                                       |
                 ASP or IASP           |    Serving or Home MSP
                                       |
                  +-------+            |        +-------+
                  |       |------------|--------|       |
                  |AAA-NA |            |        |AAA-MS |
                  |Server |-----+      |        |Server |
                  +-------+     |      |        +-------+
                      |         |      |           |
                      |         |      |           |
                      |     +------+   |           |
                      |     | DHCP |   |           |
                      |  +--|Server|   |           |
                      |  |  +------+   |  -----------------------
                      |  |      |      |           |  Serving MSP
   +------+         +------+    |      |         +------+
   |Mobile|         | NAS  |    |      |         | Home |
   |Node/ |---------|      |    |      |         | Agent|
   |DHCP  |         +------+    |      |         +------+
   |Client|---------------------+      |
   +------+

    Figure 1: The Basic Architecture for Bootstrapping MIP6 via DHCP

   In the typical Mobile IPv6 access scenario as shown above, the mobile
   node attaches in an Access Service Provider's (ASP) network.  During
   this attach procedure, the NAS authenticates and authorizes the
   mobile node for IPv6 access service.  In the scenario shown, the
   authentication and authorization happens via a AAA infrastructure.
   In the architecture shown above the mobile node acquires the Mobile
   IPv6 bootstrap information using Parameter Set 2 as the seed
   information as described in [I-D.ietf-mip6-bootstrap-ps].

   There are two models described in this document.  The first model
   termed as Model 1, shows how the mobile node performs Mobile IPv6
   bootstrapping operation using a DHCP server as the AAA client.  The
   DHCP server receives the Mobile IPv6 bootstrap information such as a
   home agent address, a home link prefix information from the AAA-MS
   (AAA for Mobility Service) server in the home Mobility Service
   Provider (MSP) via the AAA-NA (AAA for Network Access) server in the
   ASP.  The AAA-MS server may also send the delayed authentication key
   to the DHCP server for DHCP authentication [RFC3118].  The details of
   the procedures and call flows are described in Section 3 of this
   document.

   In the second model termed as Model 2, the NAS authenticates and



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   authorizes the mobile node via the AAA infrastructure.  The mobile
   node still uses Parameter Set 2 as defined in
   [I-D.ietf-mip6-bootstrap-ps].  The NAS receives the Mobile IPv6
   bootstrap information from the AAA-MS server in the home MSP via the
   AAA-NA server in the ASP.  The NAS forwards the received Mobile IPv6
   bootstrap information along with any delayed authentication parameter
   such as the shared secret for the authenticator calculation [RFC3118]
   to the DHCP server.  In this model, the NAS acts as the authorization
   delegation point as described in
   [I-D.ohba-aaaarch-authorization-delegation].  The mobile node
   acquires the Mobile IPv6 bootstrap information from the DHCP server
   via the normal DHCPv6 procedures with optional delayed authentication
   option.  The details of the procedures involved in Model 2 is
   described in Section 4 of this document.





































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3.  Model 1: NAS as a AAA Client for Mobility Service

   In this model, the DHCPv6 server acts as a AAA client for mobility
   service.  In this model, AAA for mobility service is used not only
   for retrieving Mobile IPv6 bootstrap information but also DHCPv6
   delayed authentication keys from the AAA infrastructure.  A home
   address is assigned to the mobile node either through DHCPv6 or
   through IKE.

              Network Access
      Client  Authentication
    +-------+    Protocol             AAA-NA       --------------
    |Network--------------- NAS ----------------- (              )
    |Access |                                     (              )
    |Client |                                     (              )
    | |     |                                     (     AAA      )
    | |DHCP |DHCPv6                               (Infrastructure)
    | vkey  |w/delayed auth.          AAA-MS      (              )
    |DHCP -------------- DHCP Server ------------ (              )
    |Client |<---                  <---           --------------
    |       |MIP6 bootinfo       MIP6 bootinfo{HA[,HoA]} |
    |       |{HA[,HoA]}          DHCP key                |
    |       |                                            | AAA-MS
    |       |   IKE                                      |
    |Mobile-------------- Home Agent --------------------+
    |Node   |<---                  <---
    +-------+ MIP6 bootinfo           MIP6 bootinfo
              {[HoA]}                 {IKE credential[,HoA]}


      Figure 2: DHCPv6 Server as a AAA Client for Mobility Service

   In this model, the bootstrapping procedure is executed as described
   below;

   1.  First, network access authentication is executed by using a
       network access authentication protocol and a AAA-NA protocol.

   2.  After IP connectivity is established, the DHCP client sends a
       request message (DHCP-SOLICIT).

   3.  When the DHCP server has received the request message, it
       requests Mobile IPv6 bootstrap information and a DHCP delayed
       authentication key [RFC3315][RFC3118] to the AAA infrastructure.

   4.  According to the identifier of the mobile node such as a MAC
       address or an NAI (Network Access Identifier) which is included
       in a AAA-MS protocol request sent from the DHCP server, the AAA



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       server selects the Mobile IPv6 bootstrap information and a DHCP
       delayed authentication key, and sends these parameters to the
       DHCP server.

   5.  The DHCP server executes delayed authentication with the
       retrieved key.

   6.  When the DHCP server receives a valid DHCP Request message
       (DHCP-REQUEST) from the DHCP client, it creates the binding for
       the DHCP client and sends a reply message (DHCP-REPLY) including
       "confirmed" configuration information including Mobile IPv6
       bootstrap information such as a home agent address and a home
       prefix.

   7.  The mobile node starts Mobile IPv6 binding update procedure.
       When the home agent receives an authentication request message
       (e.g., an IKE_SA_INIT request message in IKEv2) from the mobile
       node, it requests IKE credentials such as a symmetric key to the
       AAA server.  Alternatively, the AAA server may send the IKE
       credentials to the home agent before the home agent receives the
       authentication request message.

   8.  The home agent authenticates the mobile node by using the IKE
       credentials.

   The DHCP delayed authentication key and a shared secret used for IKE
   can be derived dynamically in network access authentication protocol
   exchanges based on e.g., IEEE 802.1X or PANA.

   Figure 3 shows an example sequence.  For simplicity, it is assumed in
   Figure 3 that the AAA-NA server and the AAA-MS server are integrated
   in a single AAA server.



















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     Mobile Node/              NAS/          Home Agent               AAA
     DHCP Client             DHCP Server                            Server
         |Network Access         |                                     |
         |Authentication Protocol|            AAA-NA                   |
         |<--------------------->|<----------------------------------->|
         | DHCP-SOLICIT          |               |                     |
         |---------------------->| AAA-MS(REQUEST parameters)          |
         |                       |------------------------------------>|
         |                       |  AAA-MS(parameters)                 |
         |                       |<------------------------------------|
         |                +---------------+      |                     |
         |                | Delayed auth. |      |                     |
         |                +---------------+      |                     |
         | DHCP-ADVERTISE       |                |                     |
         |(bootstrap info.)     |                |                     |
         |<---------------------|                |                     |
   +--------------+             |                |                     |
   | Delayed Auth |             |                |                     |
   +--------------+             |                |                     |
         |  DHCP-REQUEST        |                |                     |
         |--------------------->|                |                     |
         |                +---------------+      |                     |
         |                | Delayed auth. |      |                     |
         |                +---------------+      |                     |
         |                       |               |                     |
         |                +----------------+     |                     |
         |                | create binding |     |                     |
         |                +----------------+     |                     |
         |                       |  <Report authentication result>     |
         | DHCP-REPLY            |- - - - - - - - - - - - - - - - - - >|
         | [confirmed bootstrap info.]           |                     |
         |<----------------------|               |                     |
   +--------------+              |               |                     |
   | Delayed Auth |              |               |                     |
   +--------------+              |               |                     |
         |    IKE  (authentication request)      |                     |
         |-------------------------------------->| REQUEST(key for IKE)|
         |                        |              |-------------------->|
         |                        |              | REPLY (key for IKE) |
         |                        |              |<--------------------|
         |                        |       +-----------+                |
         |                        |       | User Auth |                |
         |                        |       +-----------+                |
         |    IKE (authentication result)        |                     |
         |<--------------------------------------|                     |

                   Figure 3: Model 1 Message Sequence




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3.1  Integrated ASP Scenario

   In this scenario the ASP and MSP are in the same integrated entity
   called IASP (Integrated ASP).  Furthermore, this scenario is based on
   Parameter Set 2 where it is supposed that some dependency exists
   between AAA-NA and AAA-MS.

   In this scenario, the AAA-NA server and the AAA-MS server in the IASP
   play the role as described below.

   o  The AAA-NA server authorizes network access and the AAA-MS server
      authorizes mobility service.

   o  The AAA-MS server provides Mobile IPv6 bootstrap information to
      the DHCP server.

                        +-----------------------------+
                        | IASP(ASP+MSP)               |
   +--------+    +-------------+      +------+        |
   | Mobile |--- | NAS/        |------| Home |        |
   |  Node  |    | DHCP Server |      | Agent|        |
   +--------+    +-------------+      +------+        |
                     :  | \           : \             |
                     :  |  \ +------+ :  \ +------+   |
                     :  |   -|AAA-NA| :   -|AAA-MS|   |
                     :  |    |Server| :    |Server|   |
                     :  |    +------+ :    +------+   |
                     :  +-------------:--------:------+
                     :                : MIP6 bootinfo{IKE credential,[HoA]}
                     :                :<------>:
                     :  MIP6 bootinfo{HA[HoA]} :
                     :  [DHCP key]             :
                     :<----------------------->:
                     :                         :

              Figure 4: Integrated ASP Scenario in Model 1

   The DHCP server are also located in the IASP's network.  In general,
   we can assume that there is a security association between the DHCP
   server and the AAA server in the IASP so that the DHCP server can get
   Mobile IPv6 bootstrap information from the AAA server.

   If the mobile node is allowed to roam among IASPs, the DHCP server
   that is serving the mobile node may belong to an IASP other than the
   home IASP.  Thus, to apply this mechanism, some trust relationship
   such as a roaming agreement among the IASPs is required.





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3.2  Third Party MSP Scenario

   In this scenario, AAA servers in the ASP, the home MSP and the
   serving MSP operate as described below.

   o  The AAA-MS server in the home MSP may authorize mobility service.

   o  The AAA-MS server in the serving MSP provides Mobile IPv6
      bootstrap information to the DHCP server.

   o  The AAA-NA server in the ASP authorizes network access service.

   In this scenario, the DHCP server may belong to the ASP.  The DHCP
   server needs to get Mobile IPv6 bootstrap information from the AAA-MS
   server in the home MSP, and the home agent needs to get Mobile IPv6
   bootstrap information from the AAA-MS server in the home MSP.  So,
   some trust relationship between the home MSP and the ASP is required
   in addition to the trust relationship between the home MSP and the
   serving MSP.  In this case, the AAA-NA server in the ASP would
   contact the AAA-MS server in the home MSP and the AAA-MS server in
   the home MSP would contact the AAA-MS server in the serving MSP to
   exchange Mobile IPv6 bootstrap information for a newly authenticated
   client.




























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                      +--------------+   +-----------+
                      | ASP          |   | Serving   |
                      |              |   | MSP       |
   +-------+    +------------+       |   | +------+  |  +----------+
   |Mobile |--- |    NAS/    |       |   | | Home |  |  | Home     |
   | Node  |    |DHCP Server |       |===| | Agent|  |  | MSP      |
   +-------+    +------------+       |   | +------+  |  | +------+ |
                  :   |  \ +------+  |   |  :  \     |  | |AAA-MS| |
                  :   |   -|AAA-NA|  |   |  :   ----------|Server| |
                  :   |    |Server|  |   |  :        |  | +------+ |
                  :   |    +------+  |   +--:--------+  +----:-----+
                  :   +--------------+      :                :
                  :                         :MIP6 bootinfo{IKE credential,[HoA]}
                  :                         :<-------------->:
                  :                         : (roaming agreement)
                  :                                          :
                  :  MIP6 bootinfo {HA[HoA],[DHCP key] }     :
                  :<-------------------------------------->:
                  :         (roaming agreement)              :

             Figure 5: Third Party MSP Scenario in Model 1






























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4.  Model 2: NAS as a AAA Client for MIP6 Service

   In this model, the NAS acts as a AAA client for mobility service as
   well as a AAA client for network access.  The NAS delivers Mobile
   IPv6 bootstrap information to the DHCP server.  A home address is
   assigned to the mobile node either through DHCPv6 or through IKE.
   Note that this model is assuming a MIPv6-aware NAS in the network
   that is providing network access, where the MIPv6-aware NAS is a NAS
   that receives Mobile IPv6 bootstrap information from the AAA
   infrastructure via a AAA-MS protocol and has the responsibility to
   deliver the bootstrap information to the client by some means.

     Client   Network Access
   +-------+  Authentication
   |Network|     Protocol                AAA-NA       --------------
   |Access --------------------- NAS --------------- (              )
   |Client |      MIP6 bootinfo  |   \               (              )
   |  |DHCP|         {HA[,HoA]}, |    \              (     AAA      )
   |  |key |        [DHCP key]   |     \             (Infrastructure)
   |  |    | DHCPv6              |      \ AAA-MS     (              )
   |  v    | w/delayed auth.     v       +---------- (              )
   | DHCP -------------------- DHCP Server  <---     --------------
   |Client | <---                  MIP6 bootinfo{HA[,HoA]}  |
   |       | MIP6 bootinfo{HA[,HoA]}  [DHCP key]            | AAA-MS
   |       |                                                |
   |Mobile |        IKE                                     |
   | Node ------------------- Home Agent -------------------+
   +-------+ <---                       <--
             MIP6 bootinfo{[HoA]}          MIP6 bootinfo{IKE credential[,HoA]}

             Figure 6: NAS as a AAA Client for MIP6 Service

   When network access authentication is being carried out, mobility
   service authentication is also carried out.  That is, when the client
   requests network access to NAS by using a network access
   authentication protocol (i.e.  PANA, IEEE 802.1X), the NAS acts as a
   AAA client for network access and sends a AAA request to the AAA
   infrastructure in order to authenticate to the client.  Note that at
   the same time, the AAA client for mobility service could send a AAA
   request to the AAA infrastructure to get Mobile IPv6 bootstrap
   information.  One alternative is that the AAA request sent by the NAS
   is used to get Mobile IPv6 bootstrap information.  In this case the
   information is carried to the NAS during the AAA-NA procedure,
   meaning that the AAA-NA and AAA-MS procedures are supposed to be
   integrated in this case.

   It is also possible that the AAA client for mobility service invokes
   the AAA-MS procedure after completion of the AAA-NA procedure.  In



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   this case, the AAA-NA and AAA-MS procedures are supposed to be
   performed separately.

   In any of these previous alternatives, when a AAA request for network
   access sent by the NAS is received by the AAA infrastructure and if
   network access authentication succeeds, the AAA-MS server in the AAA
   infrastructure contacts the home agent to exchange Mobile IPv6
   bootstrap information and provide the mobility service for the mobile
   node, where the bootstrap information includes IKE credentials and
   optionally a home address.  The home address could be assigned by the
   home agent instead of the AAA-MS server.

   When the mobility service is configured, the AAA infrastructure sends
   the AAA-MS client (i.e., the NAS), the following bootstrap
   information: a home agent address chosen by the AAA-MS server in the
   AAA infrastructure and optionally a DHCP delayed authentication key
   and/or a home address.  Note that it is also possible that the DHCP
   delayed authentication key is derived by the NAS based on the
   cryptographic material (i.e.  AAA_key [I-D.ietf-eap-keying]) provided
   by the AAA-NA server in the AAA infrastructure after successful
   completion of the AAA-NA procedure.

   When the NAS receives from the AAA-MS server MIPv6 bootstrap
   information for the client for which the AAA-NA procedure has been
   successfully completed, it pushes the information to the DHCP server.
   There are several protocols that can be used for carrying Mobile IPv6
   bootstrap information and a DHCP delayed authentication key from the
   NAS to the DHCP server.  SNMP is one such protocol.

   After that, the client obtains the Mobile IPv6 bootstrap information
   through DHCP.  A DHCP delayed authentication key is obtained through
   the network access authentication procedure and installed to the DHCP
   client.

   Now, the client uses the obtained Mobile IPv6 bootstrap information
   to know which home agent should be contacted.  Optionally the
   bootstrap information contains a home address though it is also
   possible that a home address is securely assigned through IKE between
   the mobile node and the home agent.

4.1  Integrated ASP Scenario

   In this deployment scenario (as it is specified in
   [I-D.ietf-mip6-bootstrap-ps]) the ASP and MSP are in the same
   integrated entity called IASP (Integrated ASP).  Furthermore, this
   scenario is based on Parameter Set 2 where it is supposed that some
   dependency exists between AAA-NA and AAA-MS.  The following two cases
   are considered for this scenario.



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   o  In a single domain case where the home/serving ASP and the home/
      serving MSP are in the same IASP.  In this case, the AAA
      infrastructure and rest of entities (the NAS, the DHCP server, the
      home agent, etc.) are managed by the same IASP.

   o  In a roaming case where really the AAA infrastructure shown in
      Figure 6 is at least divided in two AAA infrastructures: the AAA
      infrastructure of the serving IASP and the AAA infrastructure of
      the home IASP.

   If the mobility service is provided by the home IASP, the home agent
   depicted in Figure 6 belongs to the home IASP and it is configured by
   the AAA-MS server of the home IASP.  On the other hand, if the
   mobility service is provided by the serving IASP, the home agent
   belongs to the serving IASP and configured by the AAA-MS server of
   the serving IASP.

4.2  Third Party MSP Scenario

   This scenario could fall into either Parameter Set 1 or Parameter Set
   2 depending on whether there is a dependency between AAA-NA and
   AAA-MS.  The first case is out of scope of this document however
   second one is in scope.  Parameter Set 2 case happens when there is
   some trust relationship between the ASP and the home MSP in addition
   to the trust relationship between the home MSP and the serving MSP.
   In this case, the AAA-NA server in the ASP would contact the AAA-MS
   server in the home MSP and the AAA-MS server in the home MSP would
   contact the AAA-MS server in the serving MSP to exchange Mobile IPv6
   bootstrap information for a newly authenticated client.





















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5.  Comparison with Other Bootstrapping Architectures

5.1  Home Agent as NAS for AAA for Mobility Service

   In [I-D.yegin-mip6-aaa-fwk], a bootstrapping architecture is defined
   based on an assumption that the mobile node is aware of its home
   agent address by some means.  The known home agent acts as a NAS for
   AAA for mobility service.  This architecture is simpler than other
   architectures.  However, if the operator wants to have more
   flexibility in assignment of Mobile IPv6 bootstrap information
   including home agent addresses, e.g., assigning different home agents
   depending on the profile of the subscriber of the Mobile IPv6
   service, then other architectures like the one described in this
   document would be useful.

5.2  MIPv6 Authorization and Configuration based on EAP

   The architecture proposed in [I-D.giaretta-mip6-authorization-eap]
   uses EAP for conveying Parameter Set 2 of
   [I-D.ietf-mip6-bootstrap-ps] between the mobile node and the AAA-NA
   server.  An advantage of this architecture is that access networks
   can be transparent to the bootstrapping procedure.  A disadvantage is
   its potential complexity in multi-domain environments where Mobile
   IPv6 bootstrap information may be assigned by the visited
   administrative domain, not by the home administrative domain of the
   mobile node.  In this case, the bootstrap information would need to
   be transferred from the visited administrative domain to the AAA-NA
   server in the home administrative domain in order to carry them to
   the mobile node over EAP.  Also, this architecture requires existing
   EAP methods to be modified in order to carry Mobile IPv6 bootstrap
   information.




















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6.  Security Considerations

   The bootstrapping architecture defined in this document uses DHCP in
   the visited network for carrying Mobile IPv6 bootstrap information to
   the mobile node.  In an environment where the underlying AAA
   infrastructure consists of multiple administrative domains, it is
   possible that the Mobile IPv6 bootstrap information that is assigned
   and issued by a home administrative domain of the mobile node are
   passed to the visited administrative domain, which would result in
   some topological information of the home administrative domain such
   as home agent addresses to be known to the visited administrative
   domain unless the information is encrypted between the home
   administrative domain and the mobile node.  However, such information
   is eventually carried in clear text once the mobile node starts using
   the bootstrap information by sending Mobile IPv6 Binding Update as
   well as subsequent data packets and will be known to the visited
   administrative domain.  In this regard, the security risk of this
   bootstrapping architecture is not much different from that of other
   bootstrapping architectures if the bootstrap information are finally
   used by the mobile node.

   On the other hand, it is possible that the Mobile IPv6 bootstrap
   information are delivered to the mobile node but not used by the
   mobile at all.  In this case, an operator of the home administrative
   domain may want to avoid unnecessary information leakage to the
   visited administrative domain.  To achieve this, the bootstrap
   information delivered via DHCP in the visited access network may be
   encrypted by using the security association between the home
   administrative domain and the mobile node.  In this case, the DHCP
   server would act as a configuration server for distributing opaque
   configuration parameters.




















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7.  Open Issues

   o  In the hybrid scenario of integrated ASP and third party MSP
      scenarios, it is possible that both the MSP in the integrated ASP
      and the third party MSP are able to provide Mobile IPv6 bootstrap
      information for the mobile node.  In such a scenario, some policy
      might be needed for the mobile node and/or the MSPs to choose an
      appropriate MSP that provides bootstrap information to the mobile
      node or to have both MSPs provide bootstrap information to the
      mobile node.

   o  Model 1 might have some security issue if the AAA server gives
      Mobile IPv6 bootstrap information and a DHCP delayed
      authentication key to a DHCP server per request from a DHCP client
      which is actually not authenticated and authorized for access to
      the network served by the DHCP server.



































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8.  References

8.1  Normative References

   [I-D.ietf-mip6-bootstrap-ps]
              Patel, A., "Problem Statement for bootstrapping Mobile
              IPv6", draft-ietf-mip6-bootstrap-ps-01 (work in progress),
              October 2004.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and
              M. Carney, "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6)", RFC 3315, July 2003.

8.2  Informative References

   [I-D.ohba-aaaarch-authorization-delegation]
              Ohba, Y., "An Extended AAA Authorization Framework with
              Delegation",
              draft-ohba-aaaarch-authorization-delegation-00 (work in
              progress), September 2004.

   [RFC3118]  Droms, R. and W. Arbaugh, "Authentication for DHCP
              Messages", RFC 3118, June 2001.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J. and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)", RFC
              3748, June 2004.

   [I-D.ietf-eap-keying]
              Aboba, B., "Extensible Authentication Protocol (EAP) Key
              Management Framework", draft-ietf-eap-keying-03 (work in
              progress), July 2004.

   [I-D.yegin-mip6-aaa-fwk]
              Yegin, A., "AAA Mobile IPv6 Application Framework",
              draft-yegin-mip6-aaa-fwk-00 (work in progress), September
              2004.

   [I-D.giaretta-mip6-authorization-eap]
              Giaretta, G., "MIPv6 Authorization and Configuration based
              on EAP", draft-giaretta-mip6-authorization-eap-02 (work in
              progress), October 2004.

   [I-D.ietf-dhc-agentopt-radius]
              Droms, R. and J. Schnizlein, "RADIUS Attributes Sub-option
              for the DHCP Relay Agent Information Option",
              draft-ietf-dhc-agentopt-radius-08 (work in progress),
              September 2004.



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Authors' Addresses

   Yoshihiro Ohba
   Toshiba America Research, Inc.
   1 Telcordia Drive
   Piscataway, NJ  08854
   USA

   Phone: +1 732 699 5305
   EMail: yohba@tari.toshiba.com


   Rafael Marin Lopez
   University of Murcia
   30071 Murcia
   Spain

   EMail: rafa@dif.um.es


   Mayumi Yanagiya
   NTT Network service systems laboratories, NTT Corporation
   9-11, Midori-Cho, 3-Chome
   Musashino-Shi, Tokyo 180-8585
   Japan

   EMail: yanagiya.mayumi@lab.ntt.co.jp


   Hiroyuki Ohnishi
   NTT Network service systems laboratories, NTT Corporation
   9-11, Midori-Cho, 3-Chome
   Musashino-Shi, Tokyo 180-8585
   Japan

   EMail: ohnishi.hiroyuki@lab.ntt.co.jp


   Kuntal Chowdhury
   Nortel Networks
   2221 Lakeside Blvd.
   Richardson, TX 75082
   U.S.A.

   EMail: chowdury@nortelnetworks.com






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