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Versions: 00 01 02 03 04 05 RFC 5164

MIPSHOP                                                         T. Melia
Internet-Draft                                                       NEC
Intended status: Informational                               E. Hepworth
Expires: May 15, 2008                        Siemens Roke Manor Research
                                                         S. Sreemanthula
                                                   Nokia Research Center
                                                                 Y. Ohba
                                                                 Toshiba
                                                                G. Vivek
                                                                   Intel
                                                             J. Korhonen
                                                             TeliaSonera
                                                               R. Aguiar
                                                                      IT
                                                                  S. Xia
                                                                  HUAWEI
                                                       November 12, 2007


             Mobility Services Transport: Problem Statement
                      draft-ietf-mipshop-mis-ps-05

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   This Internet-Draft will expire on May 15, 2008.

Copyright Notice



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   Copyright (C) The IETF Trust (2007).

Abstract

   There are on-going activities in the networking community to develop
   solutions that aid in IP handover mechanisms between heterogeneous
   wired and wireless access systems including, but not limited to, IEEE
   802.21.  Intelligent access selection, taking into account link layer
   attributes, requires the delivery of a variety of different
   information types to the terminal from different sources within the
   network and vice-versa.  The protocol requirements for this
   signalling have both transport and security issues that must be
   considered.  The signalling must not be constrained to specific link
   types, so there is at least a common component to the signalling
   problem which is within the scope of the IETF.  This draft presents a
   problem statement for this core problem.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2]





























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Definition of Mobility Services  . . . . . . . . . . . . . . .  5
   4.  Deployment Scenarios for MoS . . . . . . . . . . . . . . . . .  5
     4.1.  End-to-End Signalling and Transport over IP  . . . . . . .  6
     4.2.  End-to-End Signalling and Partial Transport over IP  . . .  6
     4.3.  End-to-End Network-to-Network Signalling . . . . . . . . .  7
   5.  MoS Transport Protocol Splitting . . . . . . . . . . . . . . .  7
     5.1.  Payload Formats and Extensibility Considerations . . . . .  8
     5.2.  Requirements on the Mobility Service Transport Layer . . .  9
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   8.  Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . . 13
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   10. Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     10.1. General requirements . . . . . . . . . . . . . . . . . . . 14
     10.2. IETF transport protocol requirements . . . . . . . . . . . 15
     10.3. IETF discovery protocol requirements . . . . . . . . . . . 15
     10.4. IETF security requirements . . . . . . . . . . . . . . . . 16
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     11.2. Informative References . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
   Intellectual Property and Copyright Statements . . . . . . . . . . 20

























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1.  Introduction

   This Internet Draft provides a problem statement for the exchange of
   information to support handover in heterogeneous link environments
   [1] .  This mobility support service allows more sophisticated
   handover operations by making available information about network
   characteristics, neighboring networks and associated characteristics,
   indications that a handover should take place, and suggestions for
   suitable target networks to which to handover.  The mobility support
   services are complementary to IP mobility mechanisms [4], [5], [6],
   [7], [8], [9] to enhance the overall performance and usability
   perception.

   There are two key attributes to the handover support service problem
   for inter-technology handovers:

   1.  The Information: the information elements being exchanged.  The
       messages could be of different nature, such as information,
       commands to perform an action, or events informing of a change,
       potentially being defined following a common structure.

   2.  The Underlying Transport: the transport mechanism to support
       exchange of the information elements mentioned above.  This
       transport mechanism includes information transport, discovery of
       peers, and the securing of this information over the network.

   The initial requirement for this protocol comes from the need to
   provide a transport for the Media Independent Handover (MIH) protocol
   being defined by IEEE 802.21[1] which is not bound to any specific
   link layer and can operate over more that one network-layer hop.  The
   solution should be flexible to accommodate evolution in the MIH
   standard, and should also be applicable for other new mobility
   signalling protocols which have similar message patterns and
   discovery and transport requirements.

   The structure of this document is as follows.  Section 3 defines
   mobility services.  Section 4 provides a simple model for the
   protocol entities involved in the signalling and their possible
   relationships.  Section 5 describes a decomposition of the signalling
   problem into service specific parts and a generic transport part.
   Section 5.2 describes more detailed requirements for the transport
   component.  Section 7 provides security considerations, and Section 8
   summarizes the conclusions and open issues.


2.  Terminology

   The following abbreviations are used in the document:



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      MIH: media independent handover

      MN: mobile node

      NN: network node, intended to represent some device in the network
      (the location of the node e.g. in the access network, home network
      is not specified, and for the moment it is assumed that they can
      reside anywhere).

      EP: endpoint, intended to represent the terminating endpoints of
      the transport protocol used to support the signalling exchanges
      between nodes.


3.  Definition of Mobility Services

   As mentioned in the introduction mobility (handover) support in
   heterogeneous wireless environments requires functional components
   located either in the mobile terminal or in the network to exchange
   information and eventually to take decisions upon this information
   exchange.  For instance traditional host-based handover solutions
   could be complemented with more sophisticated network-centric
   solutions.  Also, neighborhood discovery, potentially a complex
   operation in heterogeneous wireless scenarios, can result in a
   simpler step if implemented with an unified interface towards the
   access network.

   In this document the different supporting functions for media
   independent handover (MIH) management are generally referred as
   Mobility Services (MoS) having different requirements for the
   transport protocol.  These requirements and associated
   functionalities are the focus of this document.  Speaking 802.21
   terminology MoS can be regarded as Infomation Services (IS), Event
   Services (ES), Command Service (CS).


4.  Deployment Scenarios for MoS

   The deployment scenarios are outlined in the following sections.
   Note: while MN-to-MN signalling exchanges are theoretically possible,
   these are not currently being considered.

   The following scenarios are discussed for understanding the overall
   problem of transporting MIH protocol.  Although these are all
   possible scenarios and MIH services can be delivered through link-
   layer specific solutions and/or through a "layer 3 or above"
   protocol, this problem statement focuses on the delivery of
   information for mobility services for the latter case only.



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4.1.  End-to-End Signalling and Transport over IP

   In this case, the end-to-end signalling used to exchange the handover
   information elements (the Information Exchange) runs end-to-end
   between MN and NN.  The underlying transport is also end-to-end

           +------+                              +------+
           |  MN  |                              |  NN  |
           | (EP) |                              | (EP) |
           +------+                              +------+
                        Information Exchange
               <------------------------------------>

               /------------------------------------\
              <          Transport over IP           >
               \------------------------------------/

               Figure 1: End-to-end Signalling and Transport

4.2.  End-to-End Signalling and Partial Transport over IP

   As before, the Information Exchange runs end-to-end between the MN
   and the second NN.  However, in this scenario, some other transport
   means than IP is used from the MN to the first NN, and the transport
   over IP is used only between NNs.  This is analogous to the use of
   EAP end-to-end between Supplicant and Authentication Server, with an
   upper-layer multihop protocol such as RADIUS used as a backhaul
   transport protocol between an Access Point and the Authentication
   Server.


           +------+           +------+           +------+
           |  MN  |           |  NN  |           |  NN  |
           |      |           | (EP) |           | (EP) |
           +------+           +------+           +------+
                        Information Exchange
               <------------------------------------>

                (Transport over  /------------------\
               <--------------->< Transport over IP  >
                    e.g. L2)     \------------------/

                        Figure 2: Partial Transport








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4.3.  End-to-End Network-to-Network Signalling

   In this case NN to NN signalling is envisioned.  Such model should
   allow different network components to gather information from each
   other.  This is useful for instance in conditions where network
   components need to take decisions and instruct mobile terminals of
   operation to be executed.

                 +------+          +------+
                 |  NN  |          |  NN  |
                 | (EP) |          | (EP) |
                 +------+          +------+
                    Information Exchange
                    ------------------->
                    <-------------------

                    /----------------\
                   <    Transport     >
                    \----------------/

            Figure 3: Information Exchange between different NN

   Network nodes exchange information about connected terminals status.


5.  MoS Transport Protocol Splitting

   Figure 4 shows a model where the Information Exchanges are
   implemented by a signalling protocol specific to a particular
   mobility service, and these are relayed over a generic transport
   layer (the Mobility Service Transport Layer).




















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                          +----------------+          ^
                          |Mobility Support|          |
                          |   Service 2    |          |
       +----------------+ |                |          | Mobility Service
       |Mobility Support| +----------------+          |    Signaling
       |    Service 1   |    +----------------+       |      Layer
       |                |    |Mobility Support|       |
       +----------------+    |   Service 3    |       |
                             |                |       |
                             +----------------+       V
     ================================================
        +---------------------------------------+     ^ Mobility Service
        |  Mobility Service Transport Protocol  |     |    Transport
        +---------------------------------------+     V      Layer
     ================================================
        +---------------------------------------+
        |                   IP                  |
        +---------------------------------------+

                    Figure 4: Handover Services over IP

   The Mobility Service Transport Layer provides certain functionality
   (outlined in Section 5.2) to the higher layer mobility support
   services in order to support the exchange of information between
   communicating mobility service functions.  The transport layer
   effectively provides a container capability to mobility support
   services, as well as any required transport and security operations
   required to provide communication without regard to the protocol
   semantics and data carried in the specific mobility services.

   The Mobility Support Services themselves may also define certain
   protocol exchanges to support the exchange of service specific
   Information Elements.  It is likely that the responsibility for
   defining the contents and significance of the Information Elements is
   the responsibility of other standards bodies other than the IETF.
   Example mobility services include the Information Services, Event and
   Command services.

5.1.  Payload Formats and Extensibility Considerations












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   The format of the Mobility Service Transport Protocol (MSTP) is as
   follows:

   +----------------+----------------------------------------+
   |Mobility Service|           Opaque Payload               |
   |Transport Header|     (Mobility Support Service)         |
   +----------------+----------------------------------------+
   This figure shows the case for a MIH message smaller than the MTU of
   the path to the destination.  A larger payload may require the
   transport protocol to transparently fragment and reassemble the MIH
   message.

                       Figure 5: Protocol Structure

   The opaque payload encompasses the Mobility Support Service (MSTP)
   information that is to be transported.  The definition of the
   Mobility Service Transport Header is something that is best addressed
   within the IETF.  MSTP does not inspect the payload and any required
   information will be provided by the MSTP users.

5.2.  Requirements on the Mobility Service Transport Layer

   The following section outlines some of the general transport
   requirements that should be supported by the Mobility Service
   Transport Protocol.  Analysis has suggested that at least the
   following need to be taken into account:

   Discovery:  MNs need the ability to either discover nodes that
      support certain services, or discover services provided by a
      certain node.  The service discovery can be dealt with messages as
      defined in [1].  This section refers to node-discovery in either
      scenario.  There are no assumptions about the location of these
      mobility services node within the network, therefore the discovery
      mechanism needs to operate across administrative boundaries.
      Issues such as speed of discovery, protection against spoofing,
      when discovery needs to take place, and the length of time over
      which the discovery information may remain valid all need to be
      considered.  Approaches include:

      *  Hard coding information into the MN, indicating either the IP
         address of the NN, or information about the NN that can be
         resolved onto an IP address.  The configuration information
         could be managed dynamically, but assumes that the NN is
         independent of the access network to which the MN is currently
         attached.

      *  Pushing information to the MN, where the information is
         delivered to the MN as part of other configuration operations,



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         for example, via DHCP or Router Discovery exchange.  The
         benefit of this approach is that no additional exchanges with
         the network would be required, but the limitations associated
         with modifying these protocols may limit applicability of the
         solution.

      *  MN dynamically requesting information about a node, which may
         require both MN and NN support for a particular service
         discovery mechanism.  This may require additional support by
         the access network (e.g. multicast or anycast) even when it may
         not be supporting the service directly itself.

      Numerous directory and configuration services already exist, and
      reuse of these mechanisms may be appropriate.  There is an open
      question about whether multiple methods of discovery would be
      needed, and whether NNs would also need to discover other NNs.
      The definition of a service also needs to be determined, including
      the granularity of the description.  For example IEEE 802.21
      specifies three different type of Mobility services (Information
      Services, Command Services and Event Services) that can be located
      in different portion of the network.  A MN could therefore run a
      discovery procedure of any service running in the (home or
      visited) network or could run a discovery procedure for a specific
      service.

   Information from a trusted source:  The MN uses the Mobility Service
      information to make decisions about what steps to take next.  It
      is essential that there is some way to ensure that the information
      received is from a trustworthy source.  This requirement should
      reuse trust relationships that have already been established in
      the network, for example, on the relationships established by the
      AAA infrastructure after a mutual authentication, or on the
      certificate infrastructure required to support SEND [10].
      Section 7 provides a more complete analysis.

   Security association management:  A common security association
      negotiation method, independent of any specific MSTP user, should
      be implemented.  The solution must also work in case on MN
      mobility.

   Secure delivery:  The Mobility Service information must be delivered
      securely (integrity and confidentiality) between trusted peers,
      where the transport may pass though untrusted intermediate nodes
      and networks.  The Mobility Service information should also be
      protected against replay attacks and denial of service attacks.






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   Low latency:  Some of the Mobility Services generate time sensitive
      information.  Therefore, there is a need to deliver the
      information over quite short timescales, and the required lifetime
      of a connection might be quite short lived.  (As an example, the
      frequency of messages defined in [1] varies according to the MIH
      service type.  It is expected that Events and Commands messages
      arrive at a rate of hundreds of milliseconds in order to capture
      quick changes in the environment and/ or process handover
      commands.  On the other hand, Information service messages are
      mainly exchanged each time a new network is visited which may be
      in the order of hours or days).  For reliable delivery, short-
      lived connections could be set up as and when needed, although
      there is a connection setup latency associated with this approach.
      Alternatively, a long-lived connection could be used, but this
      requires advanced warning of being needed and some way to maintain
      the state associated with the connection.  It also assumes that
      the relationships between devices supporting the mobility service
      are fairly stable.  Another alternative is connectionless
      operation, but this has interactions with other requirements such
      as reliable delivery.

   Reliability:  Reliable delivery for some of the mobility services may
      be essential, but it is difficult to trade this off against the
      low latency requirement.  It is also quite difficult to design a
      robust, high performance mechanism that can operate in
      heterogeneous environments, especially one where the link
      characteristics can vary quite dramatically.  There are two main
      approaches that could be adopted:

      1.  Assume the transport cannot be guaranteed to support reliable
          delivery.  In this case, the Mobility Support Service itself
          will have to provide a reliability mechanism (at MIH level) to
          allow communicating endpoints to acknowledge receipt of
          information.

      2.  Assume the underlying transport will provide reliable
          delivery.  There is no need in this case to provide
          reliability at MIH level.

      Guidelines provided in [3] are being considered while writing this
      document.

   Congestion Control:  A Mobility Service may wish to transfer small or
      large amounts of data, placing different requirements for
      congestion control in the transport.  (As an example, MIH message
      [1] size varies widely from about 30 bytes (for a broadcast
      capability discovery request) to around 65000 bytes (for an IS
      MIH_Get_Information response primitive).  A typical MIH message



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      size for the Events and Commands services service ranges between
      50 to 100 bytes).  The solution should consider different
      congestion control mechanisms depending on the amount of data
      generated by the application (MIH) as suggested in [3].

   Fragmentation and reassembly:  ES and CS messages are small in
      nature, are sent frequently, and may wish trade reliability in
      order to satisfy the tight latency requirements.  On the other
      hand, IS messages are more resilient in terms of latency
      constraints and some long IS messages could exceed the MTU of the
      path to the destination.  Depending on the choice of the transport
      protocol different fragmentation and reassembly strategies are
      required.

   Multihoming:  For some information services exchanged with the MN,
      there is a possibility that the request and response messages can
      be carried over two different links e.g. a handover command
      request is on the current link while the response could be
      delivered on the new link.  It is expected that the transport
      protocol is capable of receiving information via multiple links
      and the MSTP user to combine information belonging to the same
      session/transaction.  When mobility is applied the undelaying IP
      mobility mechanism should provide session continuty when required.

   IPv4 and IPv6 support:  The MSTP must support both IPv4 and IPv6
      including NAT traversal for IPv4 networks and firewall pass-
      through for IPv4 and IPv6 networks.


6.  IANA Considerations

   This document makes no request of IANA.


7.  Security Considerations

   Network supported mobility services aim at improving decision making
   and management of dynamically connected hosts.

   Information Services may not require authorization of the client, but
   both event and command services may authenticate message sources,
   particularly if they are mobile.  Network side service entities will
   typically need to provide proof of authority to serve visiting
   devices.  Where signalling or radio operations can result from
   received messages, significant disruption may result from processing
   bogus or modified messages.  The effect of processing bogus messages
   depends largely upon the content of the message payload, which is
   handled by the handover services application.  Regardless of the



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   variation in effect, message delivery mechanisms need to provide
   protection against tampering, spoofing, replay attacks (see
   (Section 10)).

   Sensitive and identifying information about a mobile device may be
   exchanged during handover service message exchange.  Since handover
   decisions are to be made based upon message exchanges, it may be
   possible to trace an user's movement between cells, or predict future
   movements, by inspecting handover service messages.  In order to
   prevent such tracking, message confidentiality and message integrity
   should be available.  This is particularly important since many
   mobile devices are associated with only one user, since divulging of
   such information may violate the user's privacy.  Additionally,
   identifying information may be exchanged during security association
   construction.  As this information may be used to trace users across
   cell boundaries, identity protection should be available if possible,
   when establishing SAs.

   In addition, the user should not have to disclose its identity to the
   network (any more than it needed to during authentication) in order
   to access the Mobility Support Services.  For example, if the local
   network is just aware that an anonymous user with a subscription to
   "example.com" is accessing the network, the user should not have to
   divulge their true identity in order to access the Mobility Support
   Services available locally.

   Finally, the network nodes themselves will potentially be subject to
   denial of service attacks from MNs and these problems will be
   exacerbated if operation of the mobility service protocols imposes a
   heavy computational load on the NNs.  The overall design has to
   consider at what stage (e.g. discovery, transport layer
   establishment, service specific protocol exchange) denial of service
   prevention or mitigation should be built in.


8.  Conclusions

   This Internet draft outlined a broad problem statement for the
   signalling of information elements across a network to support
   mobility services.  In order to enable this type of signalling
   service, a need for a generic transport solution with certain
   transport and security properties were outlined.  Whilst the
   motivation for considering this problem has come from work within
   IEEE 802.21, a desirable goal is to ensure that solutions to this
   problem are applicable to a wider range of mobility services.

   It would be valuable to establish realistic performance goals for the
   solution to this common problem (i.e. transport and security aspects)



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   using experience from previous IETF work in this area and knowledge
   about feasible deployment scenarios.  This information could then be
   used as an input to other standards bodies in assisting them to
   design mobility services with feasible performance requirements.

   Much of the functionality required for this problem is available from
   existing IETF protocols or combination thereof.  This document takes
   no position on whether an existing protocol can be adapted for the
   solution or whether new protocol development is required.  In either
   case, we believe that the appropriate skills for development of
   protocols in this area lie in the IETF.


9.  Acknowledgements

   Thanks to Subir Das, Juan Carlos Zuniga, Robert Hancock and Yoshihiro
   Ohba for their inputs.  Thanks to the IEEE 802.21 chair Vivek Gupta
   for coordinating the work and supporting the IETF liaison.  Thanks to
   all IEEE 802.21 WG folks who indirectly contributed to this document.


10.  Appendix

   The following list of requirements is an informative section of the
   IEEE 802.21 draft standard [1] "Requirements to support 802.21 by L3
   and above transport".

10.1.  General requirements

   The following set of requirements is applicable generically to any L3
   or above transport protocol:

   o  GR1.The transport mechanism shall provide means for communications
      between a sending MIH Protocol Entity and a receiving MIH Protocol
      Entity regardless of their network location, e.g., on the same
      subnet, or deep in the network belonging to the same or a
      different network administrative domain.

   o  GR2.The transport mechanism shall be capable of delivering time-
      sensitive information.

   o  GR3.The transport mechanism shall allow the use of effective
      security for MIH Protocol exchanges, including:

      *  mutual authentication between the communicating nodes;

      *  message authentication;




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      *  message integrity;

      *  message confidentiality

   o  GR4.The transport mechanism framework shall allow the use of
      discovery protocols as part of the L3 and above solution.

10.2.  IETF transport protocol requirements

   The following set of requirements is applicable specifically to IETF
   transport protocol:

   o  TR1.The transport protocol shall work regardless of the network
      location of the MIH Protocol Entity e.g. on the same subnet, or
      deep in the network belonging to same or different IP
      administrative domain.

   o  TR2.The transport protocol shall be capable to support both IPv4
      and IPv6 versions.

   o  TR3.The transport protocol shall be capable of delivering time-
      sensitive MIH information.

   o  TR4.The transport protocol shall enable Network address
      Translation (NAT) traversal for IPv4 networks.

   o  TR5.The transport protocol shall enable firewall pass-through for
      IPv4 and IPv6 networks.

10.3.  IETF discovery protocol requirements

   The following set of requirements is applicable specifically to IETF
   discovery protocol:

   o  DR1.The discovery protocol shall work regardless of the network
      location of the MIH Protocol Entity e.g. on the same subnet, or
      deep in the network belonging to same or different IP
      administrative domain.

   o  DR2.The discovery protocol shall work for IPv4 and IPv6 hosts.

   o  DR3.The discovery protocol shall allow for more than one MIH
      Protocol Entity to be discovered at a time.

   o  DR4.The discovery protocol shall enable Network Address Translator
      (NAT) traversal for IPv4 networks.





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   o  DR5.The discovery protocol shall enable Firewall pass-through for
      IPv4 and IPv6 networks.

10.4.  IETF security requirements

   o  SR1.The security mechanism shall provide a common security
      association (SA) negotiation method regardless of the network
      location of the MIH Protocol Entity e.g. on the same subnet, or
      deep within the network.

   o  SR2.The security mechanism shall provide mutual authentication of
      MIH end nodes.

   o  SR3.The security mechanism may provide one way authentication of
      either of MIH end nodes.

   o  SR4.The security mechanism shall provide integrity protection for
      MIH Protocol exchanges.

   o  SR5.The security mechanism may provide confidentiality for the MIH
      Protocol exchanges.

   o  SR6.The security mechanism shall protect against replay attacks.

   o  SR7.The security mechanism may protect MIH service entities and
      discovery resources against denial of service attacks.

   o  SR8.The security mechanism shall not be dependent on the MIH
      protocol.

   o  SR9.The security mechanism may provide means to reuse or fast
      reestablishment the SA due to host mobility.


11.  References

11.1.  Normative References

   [1]   "Draft IEEE Standard for Local and Metropolitan Area Networks:
         Media Independent Handover Services", IEEE LAN/MAN Draft  IEEE
         P802.21/D07.00, July 2007.

   [2]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", RFC 2119, March 2007.







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11.2.  Informative References

   [3]   Eggert, L. and G. Fairhurst, "UDP Usage Guidelines for
         Application Designers", draft-ietf-tsvwg-udp-guidelines-03
         (work in progress), September 2007.

   [4]   3GPP, "3GPP system architecture evolution (SAE): Report on
         technical options and conclusions", 3GPP TR 23.882 0.10.1,
         February 2006.

   [5]   Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
         August 2002.

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

   [7]   Moskowitz, R. and P. Nikander, "Host Identity Protocol (HIP)
         Architecture", RFC 4423, May 2006.

   [8]   Eronen, P., "IKEv2 Mobility and Multihoming Protocol (MOBIKE)",
         RFC 4555, June 2006.

   [9]   Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
         July 2005.

   [10]  Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
         Neighbor Discovery (SEND)", RFC 3971, March 2005.


Authors' Addresses

   Telemaco Melia
   NEC Europe Network Laboratories
   Kufuerstenanlage 36
   Heidelberg  69115
   Germany

   Phone: +49 6221 90511 42
   Email: telemaco.melia@netlab.nec.de












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   Eleanor Hepworth
   Siemens Roke Manor Research
   Roke Manor
   Romsey,   SO51 5RE
   UK

   Email: eleanor.hepworth@roke.co.uk


   Srivinas Sreemanthula
   Nokia Research Center
   6000 Connection Dr.
   Irving,   TX 75028
   USA

   Email: srinivas.sreemanthula@nokia.com


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

   Email: yohba@tari.toshiba.com


   Vivek Gupta
   Intel Corporation
   2111 NE 25th Avenue
   Hillsboro, OR  97124
   USA

   Phone: +1 503 712 1754
   Email: vivek.g.gupta@intel.com


   Jouni Korhonen
   TeliaSonera Corporation.
   P.O.Box 970
   FIN-00051 Sonera
   FINLAND

   Phone: +358 40 534 4455
   Email: jouni.korhonen@teliasonera.com






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   Rui L.A. Aguiar
   Instituto de Telecomunicacoes Universidade de Aveiro
   Aveiro  3810
   Portugal

   Phone: +351 234 377900
   Email: ruilaa@det.ua.pt


   Sam(Zhongqi) Xia
   Huawei Technologies Co.,Ltd
   HuaWei Bld., No.3 Xinxi Rd. Shang-Di Information Industry Base
   100085
   Hai-Dian District Beijing, P.R. China

   Phone: +86-10-82836136
   Email: xiazhongqi@huawei.com


































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