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Versions: 00 01 draft-ietf-netext-pmipv6-sipto-option

NETEXT WG                                             S. Gundavelli, Ed.
Internet-Draft                                                     Cisco
Intended status: Standards Track                                 X. Zhou
Expires: January 6, 2012                                 ZTE Corporation
                                                             J. Korhonen
                                                  Nokia Siemens Networks
                                                                G. Feige
                                                               R. Koodli
                                                                   Cisco
                                                            July 5, 2011


        IP Traffic Offload Selector Option for Proxy Mobile IPv6
           draft-gundavelli-netext-pmipv6-sipto-option-01.txt

Abstract

   This specification defines a mechanism and a related mobility option
   for carrying IP Offload traffic selectors between a mobile access
   gateway and a local mobility anchor in a Proxy Mobile IPv6 domain.
   Based on the received offload flow selectors from the local mobility
   anchor, a mobile access gateway can enable offload traffic rule on
   the selected IP flows.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 6, 2012.

Copyright Notice

   Copyright (c) 2011 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
   Provisions Relating to IETF Documents



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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . . . 3
     2.1.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4
     2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Solution Overview . . . . . . . . . . . . . . . . . . . . . . . 4
     3.1.  LMA Considerations  . . . . . . . . . . . . . . . . . . . . 5
     3.2.  MAG Considerations  . . . . . . . . . . . . . . . . . . . . 6
   4.  IP Traffic Offload Selector Option  . . . . . . . . . . . . . . 6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9

























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1.  Introduction

   Mobile Operators are expanding their network coverage by integrating
   various access technology domains into a common IP mobile core.  For
   providing IP mobility support to a mobile node irrespective of the
   access network to which it is attached, the 3GPP S2/a Proxy Mobile
   IPv6 [TS23402] interface, specified by the 3GPP system architecture,
   is providing the needed protocol glue.  When this protocol interface
   based on Proxy Mobile IPv6 [RFC5213] is used, the mobile node is
   topologically anchored on the local mobility anchor [RFC5213] in the
   home network.  The mobile node's IP traffic is always tunneled back
   from the mobile access gateway [RFC5213] in the access network to the
   local mobility anchor in the home network.

   However, with the exponential growth in the mobile data traffic,
   mobile operators are exploring new ways to offload some of the IP
   traffic flows at the nearest access edge where ever there is an
   internet peering point, as supposed to carrying it all the way to the
   mobility anchor in the home network.  Not all IP traffic needs to be
   routed back to the home network, some of the non-essential traffic
   which does not require IP mobility support can be offloaded at the
   mobile access gateway in the access network.  This approach provides
   greater leverage and efficient usage of the mobile packet core with
   increased overall network capacity and by lowering transport costs.
   The local mobility anchor in the home network can potentially deliver
   the IP flow selectors to the mobile access gateway in the access
   network, for identifying the IP flows that needs to be offloaded.

   This document defines a new mobility option, IP Traffic Offload
   Selector option for Proxy Mobile IPv6 (PMIPv6).  This option can be
   used by the local mobility anchor for notifying the flow selectors
   for that can be used by the local mobility anchor for notifying the
   mobile access gateway flows that can be offloaded at the access edge.
   Since, the mobile node's IP address topologically belongs to the home
   network, the offloaded IP traffic flows need to be NAT [RFC2663]
   translated.  Given this NAT translation requirement for the offloaded
   traffic, this approach will be limited to mobile node's IPv4 flows.
   There are better ways to solve this problem for IPv6 and with the
   goal not to create NAT66 requirement, this specification does not
   support traffic offload support for IPv6 flows.  This document also
   does not define any new semantics for flow selectors.  The flow
   identification and the related semantics are all leveraged from
   [RFC6088].


2.  Conventions and Terminology





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2.1.  Conventions

   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 [RFC2119].

2.2.  Terminology

   All the mobility related terms used in this document are to be
   interpreted as defined in the base Proxy Mobile IPv6 specifications
   [RFC5213] and [RFC5844].  Additionally, this document uses the
   following abbreviations:

   IP Flow

      IP Flow represents a set of IP packets that match a traffic
      selector.  The selector is typically based on the source IP
      address, destination IP address, source port, destination port and
      other fields in upper layer headers.

   Selective IP Traffic Offload (SIPTO)

      Ability to select specific IP flows and route them to the local
      network, as supposed to tunneling them to the home network.

   NAT (Network Address Translation)

      Network Address Translation [RFC2663] is a method by which IP
      addresses are mapped from one address realm to another, providing
      transparent routing to end hosts.


3.  Solution Overview

   The following illustrates the scenario where the mobile access
   gateway in an access network having the ability to offload some of
   the IPv4 traffic flows, based on the traffic selectors it received
   from the local mobility anchor in the home network.













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            _----_
          _(      )_
         ( Internet )
          (_      _)
            '----'
              |
   (IP Traffic Offload Point
    at access edge gateway for
    non-essential traffic)
              |
   ......................................................
              |               .        +----------------+
            +---+             .        | Operator Value |
            |NAT|             .        | Added Services |
            +---+             .        +----------------+
              |            _----_             |
           +-----+       _(      )_       +-----+
   [MN]----| MAG |======(    IP    )======| LMA |-- Internet
           +-----+       (_      _)       +-----+
                           '----'
                              .
                              .
                              .
       [Access Network]       .        [Home Network]
   ......................................................

                 Figure 1: Access Networks attached to MAG

3.1.  LMA Considerations

   The following considerations apply to the local mobility anchor and
   the mobile access gateway.

   Figure 1 explains the operational sequence of the IP Traffic Offload
   selectors between the mobile access gateway and the local mobility
   anchor.


   MN    MAG(NAT)   LMA
   |------>|        |    1. Mobile Node Attach
   |       |------->|    2. Proxy Binding Update
   |       |<-------|    3. Proxy Binding Acknowledgement (IPTS Option)
   |       |========|    4. Tunnel/Route Setup
   |       +        |    5. Installing the traffic offload rules
   |------>|        |    6. IPv4 packet from mobile node
   |       |        |    7. Forwarding rule - Tunnel home/offload
   |       |        |




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            Figure 2: Exchange of IP Traffic Offload Selectors

   o  If the received Proxy Binding Update includes the IP Traffic
      Offload Selector Option Section 4, but if the local mobility
      anchor either does not have the SIPTO capability, or it chooses to
      deny the SIPTO request, the local mobility anchor MUST ignore the
      IP Traffic Offload Selector Option and this would have no effect
      on the operation of the rest of the protocol.

   o  If the local mobility anchor has the SIPTO capability and chooses
      to deliver the flow policies, the local mobility anchor can
      construct the traffic selectors based on the routing policy and
      deliver those selectors in the Proxy Binding Acknowledgement
      message using the IP Traffic Offload Selector Option.  If the
      received Proxy Binding Update included a proposed Offload traffic
      selectors, the local mobility anchor MAY choose to honor that
      request.

3.2.  MAG Considerations

   o  The mobile access gateway MAY choose to notify the local mobility
      anchor about its SIPTO capability by including the IP Traffic
      Offload Selector Option Section 4 in the Proxy Binding Update
      message.  The included option MAY include the proposed offload
      selectors which the local mobility anchor may choose to override.
      If the mobile access gateway cannot does not have SIPTO
      capability, this option MUST NOT be included in the Proxy Binding
      Update.

   o  If there is no IP Traffic Offload Selector Option in the
      corresponding Proxy Binding Acknowledgement message, it is
      considered that the local mobility anchor does not support SIPTO
      capability, specifically, it cannot deliver selectors for IP
      traffic offload flows.

   o  If there IP Traffic Offload Selector Option in the corresponding
      Proxy Binding Acknowledgement message, it serves as an hint that
      the local mobility anchor can support SIPTO and the included
      traffic spec MUST be applied by the mobile access gateway.


4.  IP Traffic Offload Selector Option

   A new option, IP Traffic Offload Selector option, is defined for
   using it in Proxy Binding Update (PBU) and Proxy Binding
   Acknowledgement (PBA) messages exchanged between a local mobility
   anchor and a mobile access gateway.  This option is used for carrying
   the flow selectors for supporting IP traffic offload function at the



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   mobile access gateway.  The option includes the parameters for
   selecting IP flows for offload.

   The alignment requirement for this option is 4n.


   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      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |O|             Reserved                        |    TS Format  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Traffic Selector ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


               Figure 3: IP Traffic Offload Selector Option

   Type
      <IANA>

   Length
      8-bit unsigned integer indicating the length in octets of the
      option, excluding the type and length fields.

   Reserved  This field is unused for now.  The value MUST be
      initialized to 0 by the sender and MUST be ignored by the
      receiver.

   TS Format  An 8-bit unsigned integer indicating the Traffic Selector
      Format.  Value "0" is reserved and MUST NOT be used.  The value of
      (1) is assigned for IPv4 Binary Traffic Selector [RFC6088].

   TS Selector  A variable-length opaque field for including the traffic
      specification identified by the TS format field.  When the value
      of TS Format field is set to (1), the format that follows is the
      IPv4 Binary Traffic Selector specified in section 3.1 of
      [RFC6088].


5.  IANA Considerations

   This document requires the following two IANA actions.

   o  Action-1: This specification defines a new Mobility Header option,
      IP Traffic Offload Selector option.  This option is described in
      Section 4.  The Type value for this option needs to be assigned



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      from the same numbering space as allocated for the other mobility
      options [RFC3775].

   o  Action-2: The Sub-type field of the IP Traffic Offload Selector
      option introduces a new number space.  This number space needs to
      be managed by IANA, under the Registry, IP Traffic Offload
      Selector Type Registry.  This specification reserves the sub-type
      value of (1) and (2).  Approval of new sub-type values are to be
      made through IANA Expert Review.


6.  Security Considerations

   The IP Traffic Offload Selector option defined in this specification
   is for use in Proxy Binding Update and Proxy Binding Acknowledgement
   messages.  This option is carried like any other mobility header
   option as specified in [RFC5213] and does not require any special
   security considerations.  Carrying IP traffic offload selectors does
   not introduce any new security vulnerabilities.


7.  Acknowledgements

   The authors would like to thank Rajesh Pazhyannur, Kent Leung, Mark
   Grayson, Frank Brockners, Woj Dec, and Steve Wood for all the
   discussions related to the topic of IP traffic offload.  The authors
   would like to acknowledge the work related SIPTO in 3GPP SA2 working
   group.


8.  References

8.1.  Normative References

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

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

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.

   [RFC6088]  Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont,
              "Traffic Selectors for Flow Bindings", RFC 6088,
              January 2011.





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8.2.  Informative References

   [RFC2663]  Srisuresh, P. and M. Holdrege, "IP Network Address
              Translator (NAT) Terminology and Considerations",
              RFC 2663, August 1999.

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

   [TS23402]  3GPP, "Architecture enhancements for non-3GPP accesses",
              2010.


Authors' Addresses

   Sri Gundavelli (editor)
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Email: sgundave@cisco.com


   Xingyue Zhou
   ZTE Corporation
   No.68 Zijinghua Rd
   Nanjing
   China

   Email: zhou.xingyue@zte.com.cn


   Jouni Korhonen
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  FIN-02600
   Finland

   Email: jouni.nospam@gmail.com


   Gaetan
   Cisco
   France

   Email: gfeige@cisco.com




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   Rajeev Koodli
   Cisco
   3650 Cisco Way
   San Jose, CA  95134
   USA

   Email: rkoodli@cisco.com












































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