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Network Working Group                                         G. Wolfner
Internet-Draft                                          J. Korhonen, Ed.
Intended status: Informational                    Nokia Siemens Networks
Expires: January 7, 2010                                    July 6, 2009


              Connection Identifier for Proxy Mobile IPv6
                draft-wolfner-netext-pmip6-connid-00.txt

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
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   This Internet-Draft will expire on January 7, 2010.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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Abstract

   This document describes a Connection Identifier mobility option for
   Proxy Mobile IPv6.  The new mobility option can be used to uniquely
   identify multiple mobility sessions to the same selected service, for



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   example, in the Evolved Packet System scope.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Proxy Mobile IPv6 Domain Assumptions  . . . . . . . . . . . . . 4
   4.  Connection Identifier Mobility Option . . . . . . . . . . . . . 4
   5.  Processing Considerations . . . . . . . . . . . . . . . . . . . 5
     5.1.  Capability Exchange . . . . . . . . . . . . . . . . . . . . 5
     5.2.  Extensions to Binding Caches and Lookups  . . . . . . . . . 5
     5.3.  Mobile Access Gateway Considerations  . . . . . . . . . . . 5
     5.4.  Local Mobility Anchor Considerations  . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7






























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1.  Introduction

   A Mobile Node (MN) may have several mobility sessions via a single
   interface with the same Local Mobility Anchor (LMA).  An example
   where a MN may have several mobility sessions with the same LMA is
   the 3GPP environment using Enhanced Packet Core (EPC) [3GPP.23.401]
   [3GPP.23.402].  In the 3GPP environment these mobility sessions are
   called PDN connections (PDN stands for the Packet Data Network), and
   PDN connections to the same service defined by an Access Point Name
   (APN) use the same LMA instance.  In 3GPP access networks these PDN
   connections of a single MN can be identified by a unique identifier
   called EPS bearer identifier (EPS stands for the Evolved Packet
   System).  Moreover, 3GPP EPC system can be used with access networks
   that are not defined by the 3GPP such as CDMA or WLANs.  These access
   networks are generally referred as non-3GPP accesses.  Therefore, an
   unique identification of mobility sessions of a MN with the same LMA
   is also needed with those non-3GPP access networks.

   It has been identified that current Proxy Mobile IPv6 (PMIPv6)
   [RFC5213] parameters and existing IETF standardized mobility options
   are not enough in the EPC scope.  Generally in PMIPv6 and especially
   in the EPC, different APNs are identified using the Service Selection
   mobility option [RFC5149].  However, in a case of multiple PDN
   connections to the same APN, and assuming that Home Network Prefixes
   (HNP) are not always available in a Mobile Access Gateway (MAG) after
   a handover and that the "APN name" in the Service Selection mobility
   option cannot be decorated (i.e. making each APN unique), there is a
   need for a new identifier to uniquely identify PDN connections to the
   same APN.

   This document describes a new Connection Identifier (CID) mobility
   option for PMIPv6.  The Connection Identifier mobility option enables
   that a MN can have several mobility sessions via a single interface
   with the same LMA by carrying an unique connection identifier.  This
   allows the MAG and the LMA to uniquely identify mobility sessions of
   a MN.  The combination of MN-Identifier + Service Selection +
   Connection Identifier can uniquely identify mobility sessions even if
   the selected service on each mobility session for the same MN-
   Identifier are the same.  How the Connection Identifier is created
   and learnt by the MAG, is out of the scope of this document.  The MAG
   may learn this identifier for example from "lower layers" or via
   external control signaling during the PDN connection setup.  After a
   successful creation of a mobility session, and an allocation of the
   Connection Identifier, both the MAG and LMA MUST include the
   Connection Identifier in all subsequent PMIPv6 binding management
   messages related to that mobility session.





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2.  Requirements

   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].


3.  Proxy Mobile IPv6 Domain Assumptions

   The functionality described in this specification is supported only
   when multiple mobility sessions to the same selected service are
   anchored to a single LMA.  Also the multiple mobility sessions to the
   same selected service that the MN is using go via the same MAG.


4.  Connection Identifier Mobility Option

   At most one Connection Identifier mobility option MAY be included in
   any Proxy Binding Update (PBU) message sent by the MAG.  The LMA MUST
   echo the received Connection Identifier back in a Proxy Binding
   Acknowledgement (PBA) message, assuming the LMA understands the
   Connection Identifier mobility option in the first place.  The echoed
   Connection Identifier mobility option MUST be an unchanged copy of
   the Connection Identifier mobility option received in the
   corresponding PBU message.

   The Connection Identifier mobility option has the alignment
   requirement of 4n+2 and the following format:


    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
                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                   | Option Type   | Option Length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Connection Identifier                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Connection Identifier Mobility Option

   Option Type

      8-bit identifier set to TBD1.








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   Option Length

      8-bit unsigned integer, representing the length in octets of the
      mobility option, not including the Option Type and Option Length
      fields.

   Connection Identifier

      A 32-bit identifier value.  The identifier value is unique within
      a MN-Identifier + Service Selection combination scope.



5.  Processing Considerations

5.1.  Capability Exchange

   The Connection Identifier mobility option in the PBU is also an
   indication to a LMA that the MAG supports multiple mobility sessions
   to the same selected service (identified by the Service Selection
   mobility option).  Similarly, the Connection Identifier mobility
   option in the PBA is an indication to the MAG that the LMA supports
   the multiple mobility sessions to the same selected service.  Using
   this simple mechanism the MAG and the LMA can dynamically find out
   whether both support the multiple mobility sessions to the same
   selected service functionality.

5.2.  Extensions to Binding Caches and Lookups

   The Binding Caches (BC) and the respective Binding Cache Entries
   (BCE) are extended from those of what [RFC5213] and [RFC5149] define
   and require.  First, each BCE is extended with a connection
   identifier value field.  Second, the BC MAY be looked up using the
   Connection Identifier mobility option content as one additional
   lookup key.  For example

      MN-Identifier + Service Selection + Connection Identifier

   would uniquely identify a single BCE.

5.3.  Mobile Access Gateway Considerations

   If the multiple mobility session to the same selected service
   functionality is enabled and mutually supported by the MAG and the
   LMA, then the MAG MUST include the Connection Identifier mobility
   option in all PBUs.  How the MAG maps connections originated from the
   MN to connection identifiers is out of scope of this specification.
   The mapping of mobility sessions and connection identifiers MUST



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   remain the lifetime of the mobility session.

   How the MAG knows/learns the connection identifiers after a handover
   between MAGs is out of scope of this specification.  However,
   mechanisms such as context transfer between MAGs may be used. **
   Editor's note: these assumptions are subject to changes **

5.4.  Local Mobility Anchor Considerations

   If the multiple mobility session to the same selected service
   functionality is enabled and mutually supported by the MAG and the
   LMA, then the LMA MUST echo the Connection Identifier mobility option
   in all PBAs that it received in the corresponding PBUs.

   In a case the LMA does not support the Connection Identifier mobility
   option, the LMA MUST silently ignore the option and process the
   remaining of the PBU as defined in [RFC5213] and [RFC5149].  It is
   implementation specific which BCE for a given MN-Identifier is
   returned when e.g. the BC lookup using the MN-Identifier and the
   Service Selection option as the lookup key match multiple BCEs.


6.  Security Considerations

   The protection for the Connection Identifier mobility option depends
   on the services that are being connected to.  If the Connection
   Identifier information should not be revealed on the wire, Proxy
   Binding Updates and Proxy Binding Acknowledgements should use
   Encapsulating Security Payload (ESP) [RFC4303] in transport mode with
   a non-null encryption transform to provide message confidentiality.


7.  IANA Considerations

   A new mobility option for the use with PMIPv6 is defined in the
   [RFC3775] "Mobility Options" registry.  The mobility options are
   defined in Section 4:

     Connection Identifier mobility option   is set to TBD1


8.  Acknowledgements

   Thanks.


9.  References




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9.1.  Normative References

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

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

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

9.2.  Informative References

   [3GPP.23.401]
              3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", 3GPP TS 23.401 8.6.0, June 2009.

   [3GPP.23.402]
              3GPP, "Architecture enhancements for non-3GPP accesses",
              3GPP TS 23.402 8.6.0, June 2009.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.

   [RFC5149]  Korhonen, J., Nilsson, U., and V. Devarapalli, "Service
              Selection for Mobile IPv6", RFC 5149, February 2008.


Authors' Addresses

   Gyorgy Wolfner
   Nokia Siemens Networks

   Email: gyorgy.wolfner@nsn.com


   Jouni Korhonen (editor)
   Nokia Siemens Networks
   Linnoitustie 6
   FIN-02600 Espoo
   FINLAND

   Email: jouni.nospam@gmail.com







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