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Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 5454

Network Working Group                                        G. Tsirtsis
Internet-Draft                                                H. Soliman
Intended status: Standards Track                                 V. Park
Expires: January 2, 2007                                        Qualcomm
                                                               July 2006


                         Dual Stack Mobile IPv4
                     draft-ietf-mip4-dsmipv4-00.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on January 2, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006).













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Abstract

   This specification provides IPv6 extensions to the Mobile IPv4
   protocol.  The extensions allow a dual stack node to use IPv4 and
   IPv6 home addresses as well as to move between IPv4 and dual stack
   network infrastructures.


Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Goals  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Non-Goals  . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Extension Formats  . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  IPv6 Prefix Extension  . . . . . . . . . . . . . . . . . .  6
     3.2.  IPv6 Code Extension  . . . . . . . . . . . . . . . . . . .  7
     3.3.  IPv6 Tunneling Mode Extension  . . . . . . . . . . . . . .  8
   4.  Mobile IP Registrations  . . . . . . . . . . . . . . . . . . . 10
     4.1.  Registration Requests  . . . . . . . . . . . . . . . . . . 10
     4.2.  Registration Reply . . . . . . . . . . . . . . . . . . . . 10
     4.3.  Home Agent Considerations  . . . . . . . . . . . . . . . . 11
     4.4.  Foreign Agent Considerations . . . . . . . . . . . . . . . 12
     4.5.  Mobile Node Considerations . . . . . . . . . . . . . . . . 13
     4.6.  Dynamic IPv6 Prefix allocation . . . . . . . . . . . . . . 14
       4.6.1.  Mobile IP Style Address Allocation . . . . . . . . . . 14
       4.6.2.  Prefix Delegation  . . . . . . . . . . . . . . . . . . 15
     4.7.  Deregistration of IPv6 Prefix  . . . . . . . . . . . . . . 15
     4.8.  Registration with a private CoA  . . . . . . . . . . . . . 15
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   6.  Aknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 17
   7.  Normative References . . . . . . . . . . . . . . . . . . . . . 18
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
   Intellectual Property and Copyright Statements . . . . . . . . . . 20

















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1.  Requirements notation

   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 [RFC2119].














































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2.  Introduction

   Mobile IPv4 [RFC3344] allows a mobile node with an IPv4 address to
   maintain communications while moving in an IPv4 network.

   Extensions defined in this document allow a node that has IPv4 and
   IPv6 [RFC2460] addresses to maintain communications with either any
   of its addresses while moving in IPv4 or dual stack networks.

   Essentially, this specification separates the Mobile IPv4 signaling
   from the IP version of the traffic that it tunnels.  Mobile IPv4 with
   the present extensions remains a signaling protocol that runs over
   IPv4, and yet can set-up any combination of IPv4 and/or IPv6 over
   IPv4 tunnels.

   The aim is two-fold:

      On one hand, Mobile IPv4 with the present extensions becomes a
      powerful transition mechanism, allowing automated but controlled
      tunneling of IPv6 traffic over IPv4 tunnels.  Dual stack nodes in
      dual stack home networks can now roam to and from legacy IPv4
      networks, while IPv4 mobile nodes and networks can migrate to IPv6
      without changing mobility management, and without upgrading all
      network nodes to IPv6 at once.

      On the other hand, and more importantly, it allows dual stack
      mobile nodes and networks to utilize a single protocol for the
      movement of both IPv4 and IPv6 stacks in the network topology.

   Note that features like Mobile IPv6 [RFC3775] style route
   optimization will not be possible with this solution as it still
   relies on Mobile IPv4 signaling, which does not provide route
   optimization.

2.1.  Goals

   a.  The solution supports the registration of IPv6 address(es) and/or
       prefix(s) in addition to regular IPv4 home address registration

   b.  The solution supports dynamic IPv6 address(s)/prefix(s)
       allocations

   c.  The solution supports the above registrations with and without FA
       support







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2.2.  Non-Goals

   a.  The solution does not provide support for IPv6 care-of address
       registration















































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3.  Extension Formats

   The following extensions are defined according to this specification.

3.1.  IPv6 Prefix Extension

   A new skippable extension to the Mobile IPv4 header in accordance to
   the short extension format of [RFC3344] is defined here.

   This extension contains a mobile IPv6 network prefix and its prefix
   length.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Type     |   Length      |   Sub-Type    | Prefix Length |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                   Mobile IPv6 Network Prefix                  +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 1: IPv6 Prefix Extension

   Type

      DSMIPv4 Extensions (skippable type range to be assigned by IANA)

   Length

      20

   Sub-Type

      1 (IPv6 Prefix)

   Prefix Length

      Indicates the prefix length of the prefix included in the Mobile
      Network IPv6 Prefix Field

   Mobile IPv6 Network Prefix





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      A sixteen-byte field containing the Mobile IPv6 Network Prefix

3.2.  IPv6 Code Extension

   A new skippable extension to the Mobile IPv4 header in accordance to
   the short extension format of [RFC3344] is defined here.

   This extension defines a mobile IPv6 network prefix and its prefix
   length, as well as a code.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |   Length      |   Sub-Type    |     Code      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Prefix Length |    Reserved   |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                                                               |
      +                                                               +
      |                                                               |
      +                   Mobile IPv6 Network Prefix                  +
      |                                                               |
      +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 2: IPv6 Code Extension

   Type

      DSMIPv4 Extensions (skippable type range to be assigned by IANA)

   Length

      22

   Sub-Type

      2 (IPv6 Prefix Acknowledgment)

   Code

      A value indicating the result of the registration request with
      respect to the IPv6 home address registration

   Prefix Length





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      Indicates the prefix length of the prefix included in the Mobile
      Network IPv6 Prefix Field

   Reserved

      Set to 0 by the sender, ignored by the receiver

   Mobile IPv6 Network Prefix

      A sixteen-byte field containing the Mobile IPv6 Network Prefix

   The following values are defined for use as a Code value in the above
   extension

      0 registration accepted, IPv6 to be tunneled to HoA

      1 registration accepted, IPv6 to be tunneled to CoA

      8 reason unspecified

      9 administratively prohibited

   Note that a registration reply that does not include an IPv6 code
   extension indicates that the home agent does not support IPv6
   extensions and thus has ignored such extensions in the registration
   reply.

3.3.  IPv6 Tunneling Mode Extension

   A new skippable extension to the Mobile IPv4 header in accordance to
   the short extension format of [RFC3344] is defined here.

   This presence of this extension in a registration request message
   indicates that the sender supports the IPv6 extensions specified in
   this document.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |   Length      |    Sub-Type   |   Reserved    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  Figure 3: IPv6 Tunneling Mode Extension

   Type





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      DSMIPv4 Extensions (skippable type range to be assigned by IANA)

   Length

      4

   Sub-Type

      3 (IPv6 Tunneling Mode Extension)

   Reserved

      Set to 0 by the sender, ignored by the receiver






































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4.  Mobile IP Registrations

4.1.  Registration Requests

   A mobile IP client MAY include one or more IPv6 prefix extensions
   defined in this specification in a registration request.

   A mobile IP client MAY include exactly one IPv6 tunneling mode
   extension when it uses the collocated care-of address mode.

   When IPv6 prefix and/or IPv6 tunneling mode extension are used by the
   mobile client, they MUST be placed after the registration request
   header and before the mobile - home authentication extension so they
   MUST be included in the computation of any authentication extension.

   A foreign agent MAY include an IPv6 tunneling mode extension defined
   in the specification in a registration request when the care-of
   address mode of operation is used.

   When IPv6 tunneling mode extension are used they MUST be placed after
   the mobile - home authentication extensions and before the foreign -
   home authentication extension so they MUST be included in the
   computation of the foreign - home authentication extension when one
   exists.

4.2.  Registration Reply

   The mechanism described in the specification depends on skippable
   extensions.  For that reason a registration reply that does not
   include an IPv6 code extension, in response to a registration request
   that included an IPv6 prefix extension, indicates that the home agent
   does not support IPv6 extensions and has ignored the request.

   If an IPv6 code extension is included in a registration reply then,
   said extension indicates the success or failure of the IPv6 prefix
   registration.  The IPv6 code extension does NOT affect in any way,
   the code value in the registration reply header.

   Note that a negative IPv6 code extension has the same effect with not
   including such extension at all in the sense that in both cases the
   mobile client and foreign agent must act as if the corresponding
   request of Ipv6 prefix registration was rejected.  Of course negative
   IPv6 code extension allows the home agent to indicate why a given
   request was rejected.







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4.3.  Home Agent Considerations

   A dual stack home agent that supports the IPv6 extensions defined in
   this specification, MUST keep track of the following IPv6 related
   state for the mobile IP clients it supports, in addition to what
   state is defined in [RFC3344].

   - Registered IPv6 prefix(es) and prefix length(s)

   - Tunneling mode for IPv6 traffic:

      - Tunnel to IPv4 HoA and accept IPv6 tunneled from IPv4 HoA

      - Tunnel to CoA and accept IPv6 tunneled from CoA

   If the tunnel for IPv4 traffic terminates at a different point than
   the tunnel for IPv6 traffic (mobile client's CoA vs HoA), both
   tunnels MUST use the tunneling mechanism negotiated by the Mobile IP
   header as defined in [RFC3344].

   A home agent that supports this specification MUST be able to
   intercept IPv4 and IPv6 packets destined to registered mobile nodes
   according to mechanisms described in [RFC3344] and [RFC3775]
   specifications.  All intercepted traffic SHOULD be tunneled to the
   registered care-of address or home address of the mobile client in
   question according to the tunneling mode selected for IPv6 traffic.

   Tunneling mode selection for IPv6 traffic depends on the following
   parameters in a successful registration request:

   1) Registration request is received with one or more IPv6 prefix
   extensions.  An IPv6 tunneling mode extension is not included.

      All IPv6 packets destined to the registered IPv6 prefix(es) MUST
      be tunneled by the home agent to the registered IPv4 home address
      of the mobile.  Additionally, the home agent MUST be prepared to
      accept reverse tunneled packets from the IPv4 home address of the
      mobile encapsulating IPv6 packets sent by that mobile.

   2) Registration request is received with one or more IPv6 prefix
   extensions.  An IPv6 tunneling mode extension is included.

      All IPv6 packets destined to the registered IPv6 home address(s)
      SHOULD be tunneled by the home agent to the registered care-of
      address of the mobile client.  Additionally, the home agent SHOULD
      be prepared to accept reverse tunneled packets from the care-of
      address of the mobile encapsulating IPv6 packets sent by that
      mobile.  The home agent MAY ignore the presence of the IPv6



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      tunneling mode extension and act as in case (1) above.

   The home agent SHOULD check that all IPv6 packets received from the
   mobile client over a tunnel from the home address or the care-of
   address, include a source address that falls under the registered
   IPv6 prefix(es) for that mobile client.

   For each IPv6 prefix extensions included in a valid registration
   request, a home agent that supports this specification SHOULD include
   a corresponding IPv6 code extension.  For each accepted IPv6 prefix
   the home agent MUST decide the tunneling mode used according to this
   section and set the Code field of the IPv6 code extension to the
   appropriate value.  The omission of a given code extension is
   equivalent to the rejection of the corresponding IPv6 prefix
   extension.  The IPv6 prefix field of each of the IPv6 code extensions
   included in the registration reply MUST match a corresponding IPv6
   prefix field of the IPv6 prefix extension included in the
   corresponding registration request message.

4.4.  Foreign Agent Considerations

   A dual stack foreign agent that supports the IPv6 extensions defined
   in this specification MUST keep track of the following IPv6 related
   state for the mobile nodes it supports in addition to what state is
   defined in [RFC3344].

   - IPv6 Prefix(es) and Prefix Length(s)

   - Tunneling mode for IPv6 traffic:

      - accept IPv6 encapsulated in IPv4 and reverse tunnel IPv6

   When a foreign agent receives a registration request with IPv6 prefix
   extension(s) it has the following choices:

   1) Ignore the extension(s).  The registration request is forwarded as
   is with no IPv6 tunneling mode extension to the home agent.

      The foreign agent SHOULD operate according to [RFC3344]

   2) Attach an IPv6 tunneling mode extension to the registration
   request sent to the home agent.

      The foreign agent MUST be prepared to de-capsulate and deliver
      IPv6 packets, in addition to the IPv4 packets, sent to it in the
      home agent to foreign agent tunnel for that mobile client.  The
      foreign agent MUST be prepared to receive IPv6 packets from the
      mobile client, in addition to IPv4 packets.  All IPv6 traffic MUST



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      be reverse tunneled to the home agent by the foreign agent
      irrespectively from the reverse tunneling setting negotiated for
      IPv4 packets by mechanisms in [RFC3024]

   If the foreign agent sets the R flag included in the mobility agent
   advertisement [RFC3344] and a mobile client uses the collocated
   address model, the foreign agent MUST NOT include an IPv6 tunneling
   mode extension in the registration request messages sent from that
   mobile client.

4.5.  Mobile Node Considerations

   A dual stack mobile node that supports the extensions described in
   this document MAY use these extensions to register its IPv6 home
   address(es) and/or prefix(es) while moving between access routers.
   The mobile client MAY include one or more IPv6 Prefix extension(s) in
   the registration request.

   The mobile client MAY include one or more IPv6 Prefix extension(s) in
   the registration request.

   In this case the mobile MUST take the following action depending on
   the extensions included in the registration reply it receives in
   response to the registration request:

   1) The registration reply does not include any IPv6 code extensions.

      The mobile client SHOULD assume that the home agent does not
      support the extensions defined in this specification.  The mobile
      client SHOULD continue to operate according to RFC3344.

   2) The registration reply includes one or more IPv6 code extensions.

      The mobile client MUST match each IPv6 code extension with one of
      the IPv6 prefix extensions earlier included in the corresponding
      registration request message.

      If a matching IPv6 code extension is not included for one or more
      of corresponding IPv6 prefix extensions included in the
      registration request message, the mobile client SHOULD assume that
      these IPv6 prefixes are rejected.

      For each matching IPv6 code extensions the mobile client MUST
      inspect the Code field.  If the field is set to a rejection code
      then the corresponding IPv6 prefix registration has been rejected.
      If the field is set to an acceptance code then the corresponding
      IPv6 prefix registration has been accepted.




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      If the Code field is set to "0" then the mobile client MUST be
      prepared to send/receive IPv6 packets encapsulated in the
      bidirectional tunnel between the home agent address and the
      registered IPv4 home address of the mobile client.

      If the Code field is set to "1" then the mobile client MUST act as
      follows:

      - If the care-of address mode is used, the mobile client MUST be
      prepared to send/receive IPv6 traffic on its interface natively,
      unless reverse tunnel has been negotiated in which case both IPv4
      and IPv6 traffic MUST be reverse tunneled according to [RFC3024].

      If the collocated care-of address mode is used, the mobile client
      MUST be prepared to send/receive IPv6 packets over the
      bidirectional tunnel between the home agent address and its
      collocated care-of address.

   The mobile client SHOULD include exactly one IPv6 tunneling mode
   extension if it uses the collocated care-of address model and if it
   wants to request that IPv6 packets are tunneled to its collocated
   care-of address.  If the mobile client uses the collocated care-of
   address model but it does not include the IPv6 tunneling mode
   extension the home agent will tunnel IPv6 traffic to the mobile
   client's home address.

4.6.  Dynamic IPv6 Prefix allocation

4.6.1.  Mobile IP Style Address Allocation

   A mobile client MAY include one or more IPv6 prefix extensions with
   the IPv6 prefix field set to zero.  Such IPv6 prefix extensions
   indicate that the mobile client requests IPv6 prefix(es) to be
   assigned to it by the home agent.  The mobile client MAY set the
   prefix length field of such extensions to zero or to a length of its
   choice as a hint to the home agent.

   A home agent receiving an IPv6 prefix extension with the IPv6 prefix
   field set to zero MAY return an IPv6 Code extension with the IPv6
   prefix field set to the IPv6 prefix allocated to the mobile client.
   The length of that prefix is at the discretion of the home agent.
   The home agent MAY take into account the prefix length hint if one is
   included in the IPv6 prefix extension.

   For stateless auto-configuration of addresses [RFC2462], a mobile
   client MAY include one or more IPv6 prefix extensions with the IPv6
   Prefix field set to ::interface_identifier.  Such IPv6 prefix
   extensions indicate that the mobile client requests IPv6 address(es)



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   to be assigned to it by the home agent.  The prefix length field in
   such an extension SHOULD be set to 64 or 128.

   The home agent MAY in this case return an IPv6 Code extension with:

      - the IPv6 prefix field set to PREFIX:: and the prefix length
      field set to 64.

      - the IPv6 prefix field set to PREFIX::interface_identifier and
      the prefix length field set to 128.

   The HA SHOULD perform Duplicate Address Detection (DAD) according to
   [RFC2462] before it returns an IPv6 home address in an IPv6 Code
   extension.  If a prefix is returned DAD is not applicable.  The HA
   MUST send a Neighbor Advertisement, as defined in [RFC2461] for every
   IPv6 address it allocates with this mechanism so that all traffic to
   this address is directed to itself.

4.6.2.  Prefix Delegation

   A dual stack mobile node MAY also use Prefix Delegation as defined in
   [draft-ietf-nemo-dhcpv6-pd-01.txt] to get a prefix.  In that case the
   mobile MUST first register its IPv4 home address as per [RFC3344].
   When that is done the mobile can generate a link local IPv6 address
   and use it to send DHCP messages according to
   [draft-ietf-nemo-dhcpv6-pd-01.txt].  All IPv6 messages required for
   Prefix Delegation MUST be tunneled over the IPv4 tunnel between the
   mobile and the home agent.

4.7.  Deregistration of IPv6 Prefix

   The mobile IP registration lifetime included in the registration
   request header is valid for all binding created by the registration
   request, which may include bindings for an IPv6 Prefix(es).

   A registration request with a zero lifetime can be used to remove all
   bindings from the home agent.

   A re-registration request with non-zero lifetime can be used to
   deregister some of the registered IPv6 prefixes by not including
   corresponding IPv6 prefix extensions in the registration request
   message.

4.8.  Registration with a private CoA

   If the care-of address is a private address then Mobile IP NAT
   Traversal as described in [RFC3519] MAY be used in combination with
   the extensions described in this specification.



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5.  Security Considerations

   This specification operates in the security constraints and
   requirements of [RFC3344].  It extends the operations defined in
   [RFC3344] for IPv4 home addresses to cover IPv6 prefixes and provides
   the same level of security for both IP versions.













































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6.  Aknowledgements

   Thanks to Pat Calhoun, Paal Engelstad, Tom Hiller and Pete McCann for
   earlier work on this subject.  Thanks also to Alex Petrescu for
   suggesting the use of prefix delegation for dynamic IPv6 address
   allocation.













































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7.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

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

   [RFC2461]  Narten, T., Nordmark, E., and W. Simpson, "Neighbor
              Discovery for IP Version 6 (IPv6)", RFC 2461,
              December 1998.

   [RFC2462]  Thomson, S. and T. Narten, "IPv6 Stateless Address
              Autoconfiguration", RFC 2462, December 1998.

   [RFC2794]  Calhoun, P. and C. Perkins, "Mobile IP Network Access
              Identifier Extension for IPv4", RFC 2794, March 2000.

   [RFC3024]  Montenegro, G., "Reverse Tunneling for Mobile IP,
              revised", RFC 3024, January 2001.

   [RFC3344]  Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
              August 2002.

   [RFC3519]  Levkowetz, H. and S. Vaarala, "Mobile IP Traversal of
              Network Address Translation (NAT) Devices", RFC 3519,
              May 2003.

   [RFC3775]  Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
              in IPv6", RFC 3775, June 2004.





















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Authors' Addresses

   George Tsirtsis
   Qualcomm

   Phone: +908-947-7059
   Email: tsirtsis@qualcomm.com


   Hesham Soliman
   Qualcomm

   Phone: +614-111-410-445
   Email: hesham@qualcomm.com


   Vincent Park
   Qualcomm

   Phone: +908-947-7084
   Email: vpark@qualcomm.com






























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Full Copyright Statement

   Copyright (C) The Internet Society (2006).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
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Acknowledgment

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Tsirtsis, et al.         Expires January 2, 2007               [Page 20]


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