Separation of Control and User Plane for Proxy Mobile IPv6
draft-ietf-netext-pmip-cp-up-separation-06

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NETEXT WG                                                    R. Wakikawa
Internet-Draft                                           Softbank Mobile
Intended status: Standards Track                           R. Pazhyannur
Expires: February 13, 2015                                 S. Gundavelli
                                                                   Cisco
                                                              C. Perkins
                                                          Futurewei Inc.
                                                         August 12, 2014

       Separation of Control and User Plane for Proxy Mobile IPv6
             draft-ietf-netext-pmip-cp-up-separation-06.txt

Abstract

   This document specifies a method to split the Control Plane (CP) and
   User Plane (UP) for a Proxy Mobile IPv6 based network infrastructure.
   Existing specifications allow a mobile access gateway (MAG) to
   separate its control and user plane using the Alternate Care of
   address mobility option for IPv6, or Alternate IPv4 Care of Address
   option for IPv4.  However, the current specification does not provide
   any mechanism allowing the local mobility anchor (LMA) to perform an
   analogous functional split.  To remedy that shortcoming, this
   document specifies a mobility option enabling a LMA to provide an
   alternate LMA address to be used for the bi-directional user plane
   traffic between the MAG and LMA.  With this new option, a LMA will be
   able to use an IP address for its user plane which is different than
   the IP address used for the control plane.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 13, 2015.

Copyright Notice

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   Copyright (c) 2014 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
   (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
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   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  . . . . . . . . . . . . . . . . .  5
     2.1.  Conventions  . . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Additional Fields in Conceptual Data Structures  . . . . . . .  6
   4.  LMA User Plane Address Mobility Option . . . . . . . . . . . .  6
   5.  Protocol Configuration Variable  . . . . . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10

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1.  Introduction

   A PMIPv6 infrastructure comprises two primary entities: LMA (local
   mobility anchor) and MAG (mobile access gateway).  The interface
   between MAG and LMA consists of the control plane and user plane.
   The control plane is responsible for signaling messages between MAG
   and LMA such as the Proxy Binding Update (PBU) and Proxy Binding
   Acknowledgement (PBA) messages to establish a mobility binding.  In
   addition, the control plane components in the MAG and LMA are also
   responsible for setting up and tearing down a bi-directional tunnel
   between the MAG and LMA.  The user plane is used for carrying the
   mobile node's IP traffic between the MAG and the LMA over the bi-
   directional tunnel.

   Widely deployed mobility management systems for wireless
   communications require separation of IP transport for forwarding user
   plane and control plane traffic.  This separation offers more
   flexible deployment options for LMA and MAG entities in Proxy Mobile
   IPv6 as described in [I-D.wakikawa-req-mobile-cp-separation].  To
   meet this requirement, Proxy Mobile IPv6 (PMIPv6) requires that the
   control plane functions of the LMA to be addressable at a different
   IP address than the IP address assigned for the user plane.  However,
   PMIPv6 does not currently specify a mechanism for allowing the LMA to
   separate the control plane from the user plane.  The LMA is currently
   required to associate the IP address of the tunnel source with the
   target IP address for the control messages received from the MAG.

   The control plane and user plane components (of the MAG and LMA) are
   typically co-located in the same physical entity.  However, there are
   situations where it is desirable to have the control and user plane
   of the MAG and LMA in separate physical entities.  For example, in a
   WLAN (Wireless LAN) network, it may be desirable to have the control
   plane component of the MAG reside on the Access Controller (also
   sometimes referred to as Wireless LAN Controller (WLC)) while the
   user plane component of the MAG resides on the WLAN Access Point.
   This enables all the control plane messages to the LMA to be
   centralized while the user plane would be distributed across the
   multiple Access Points.  Similarly there is a need for either the
   control plane and user plane component of the LMA to be separated
   according to different scaling requirements, or in other cases the
   need to centralize the control plane in one geographical location
   while distributing the user plane component across multiple
   locations.  For example, as illustrated in Figure 1, the LMA and MAG
   could have one control session established for PMIPv6 control
   signaling, while maintaining separate connectivity via GRE or
   IP-in-IP tunneling for forwarding user plane traffic.

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                     MAG                    LMA
                 +--------+              +--------+
   +------+      | MAG-CP |--------------| LMA-CP |        _----_
   |  MN  |      |        |    PMIPv6    |        |      _(      )_
   |      |----  +--------+              +--------+  ===( Internet )
   +------+          :                       :           (_      _)
                 +--------+              +--------+        '----'
                 | MAG-UP |--------------| LMA-UP |
                 |        | GRE/IP-in-IP |        |
                 +--------+    /UDP      +--------+
   CP: Control Plane
   UP: User Plane

       Figure 1: Functional Separation of the Control and User Plane

   [RFC6463] and [RFC6275] enable separating the control and user plane
   in the MAG.  In particular, [RFC6463] defines the Alternate IPv4
   Proxy Care of Address Option, and [RFC6275] defines an Alternate Care
   of Address for IPv6 address.  The MAG may provide an Alternate Care
   of Address in the PBU, and if the LMA supports this option then a bi-
   directional tunnel is setup between the LMA address and the MAG's
   alternate Care of address.  However, these documents do not specify a
   corresponding option for the LMA to provide an alternate address to
   the MAG.

   This specification therefore defines a new mobility option that
   enables a local mobility anchor to provide an alternate LMA address
   to be used for the bidirectional tunnel between the MAG and LMA as
   shown in Figure 1.

   The LMA Control Plane and the LMA User Plane functions are typically
   deployed on the same IP node and in such scenario the interface
   between these functions is internal to the implementation.
   Deployments may also choose to deploy the LMA Control Plane and the
   LMA User Plane functions on seperate IP nodes.  In such deployment
   models, there needs to be a protocol interface between these two
   functions and which is outside the scope of this document.  Possible
   options for such interface include OpenFlow [OpenFlow-Spec-v1.4.0],
   FORCES [RFC5810], use of routing infrastructure
   [I-D.matsushima-stateless-uplane-vepc] or vendor specific approaches.
   This specification does not mandate a specific protocol interface and
   views this interface as a generic interface relevant more broadly for
   many other protocol systems in addition to Proxy Mobile IPv6.

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2.  Conventions and Terminology

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

   3GPP terms can be found in [RFC6459].  Other mobility related terms
   used in this document are to be interpreted as defined in [RFC5213]
   and [RFC5844].  Additionally, this document uses the following terms:

   IP-in-IP

      IP-within-IP encapsulation [RFC2473], [RFC4213]

   GRE

      Generic Routing Encapsulation [RFC1701]

   UDP Encapsulation

      Encapsulation mode based on UDP transport specified in [RFC5844]

   LMA Control Plane Address (LMA-CPA)

      The IP address on the LMA that is used for sending and receiving
      control plane traffic from the MAG.

   LMA User Plane Address (LMA-UPA)

      The IP address on the LMA that is used for sending and receiving
      user plane traffic from the MAG.

   MAG Control Plane Address (MAG-CPA)

      The IP address on the MAG that is used for sending and receiving
      control plane traffic from the LMA.

   MAG User Plane Address (MAG-UPA)

      The IP address on the MAG that is used for sending and receiving
      user plane traffic from the LMA.  This address is also referred to
      as the Alternate Care of Address.

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3.  Additional Fields in Conceptual Data Structures

   To support the capability specified in this document, the conceptual
   Binding Update List entry data structure maintained by the LMA and
   the MAG is extended with the following additional fields.

   o  The IP address of the LMA that carries user plane traffic.

   o  The IP address of the LMA that handles control plane traffic.

4.  LMA User Plane Address Mobility Option

   The LMA User Plane Address mobility option is a new mobility header
   option defined for use with PBU and PBA messages exchanged between
   the LMA and the MAG.  This option is used for notifying the MAG about
   the LMA's user plane IPv6 or IPv4 address.  There can be zero, one or
   two instances of the LMA User Plane Address mobility option present
   in the message.  When two instances of the option are present, one
   instance of the option must be for IPv4 transport and the other
   instance must be for IPv6 transport.

   The LMA User Plane Address mobility option has an alignment
   requirement of 8n+2.  Its format is as shown in Figure 2:

   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      |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   .                                                               .
   +                     LMA User Plane Address                    +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: LMA User Plane Address option format

   Type

      <IANA-1> To be assigned by IANA.

   Length

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

   Reserved

      This field is unused in this specification.  The value MUST be set
      to zero (0) by the sender and MUST be ignored by the receiver.

   LMA User Plane Address

      Contains the 32-bit IPv4 address, or the 128-bit IPv6 address of
      the LMA User plane.  When the LMA User Plane Address Mobility
      option is included in a PBU message, this field can be a zero
      length field, or it can have a value of ALL_ZERO, with all bits in
      the 32-bit IPv4 address, or the 128-bit IPv6 address set to zero.

   When including the LMA User Plane Address mobility option in the PBU,
   the MAG must apply the following rules:

   o  When using IPv4 transport for the user-plane, the IP address field
      in the option MUST be either a zero-length field, or a 4-octet
      field with ALL_ZERO value.

   o  When using IPv6 transport for the user-plane, the IP address field
      in the option MUST be either a zero-length field, or a 16-octet
      field with ALL_ZERO value.

   When the LMA includes the LMA User Plane Address mobility option in
   the PBA, the IP address field in the option MUST be set to the LMA's
   IPv4 or IPv6 address carrying user-plane traffic.

   o  When using IPv4 transport for the user-plane, the IP address field
      in the option is the IPv4 address carrying user-plane traffic.

   o  When using IPv6 transport for the user-plane, the IP address field
      in the option is the IPv6 address carrying user-plane traffic.

   The encapsulation mode that will be chosen for the user-plane between
   the MAG and the LMA has to based on the considerations specified in
   [RFC5213] and [RFC5844].

5.  Protocol Configuration Variable

   This specification defines the following configuration variable,
   which must be configurable (e.g., by the system management) on the
   LMA and MAG mobility entities.  The configured value for this
   protocol variable MUST survive server reboots and service restarts,

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   and MUST be the same for every LMA and MAG in the network domain
   supporting PMIPv6.

   Domain-wide-LMA-UPA-Support

         This variable indicates whether or not all the mobility
         entities in the PMIPv6 domain support the LMA User Plane
         Address mobility option.

         When this variable on the MAG is set to zero (0), the MAG MUST
         indicate whether it supports this feature, by including the LMA
         User Plane Address mobility option in the PBU.  If the option
         is not present in the PBU, the LMA SHALL disable this feature
         for the mobility session corresponding to the PBU.

         Setting this variable to one (1) on the MAG indicates that
         there is domain-wide support for this feature and the MAG is
         not required to include the LMA User Plane Address mobility
         option in the PBA.  In this case, the MAG MAY choose not to
         include the LMA User Plane Address mobility option in the PBU.

         When this variable on the LMA is set to zero (0), the LMA MUST
         NOT include the LMA User Plane Address mobility option in the
         PBA, unless the MAG has indicated support for this feature by
         including the LMA User Plane Address mobility option in the PBU
         message.

         Setting this variable to one (1) on the LMA indicates that
         there is domain-wide support for this feature and the LMA
         SHOULD choose to include this LMA User Plane Address mobility
         option in the PBA even if the option is not present in the PBU
         message.

         On both the LMA and the MAG, the default value for this
         variable is zero (0).  This implies that the default behavior
         of a MAG is to include this option in the PBU and the default
         behavior of a LMA is to include this option in a PBA only if
         the option is present in the PBU.

6.  IANA Considerations

   This document requires the following IANA actions.

   o  Action-1: This specification defines a new mobility header option,
      LMA User Plane Address mobility option.  The format of this option
      is described in Section 4.  The type value <IANA-1> for this
      mobility option is to be allocated from the Mobility Options

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      registry at <http://www.iana.org/assignments/mobility-parameters>.
      RFC Editor: Please replace <IANA-1> in Section 4 with the assigned
      value and update this section accordingly.

7.  Security Considerations

   The LMA User Plane Address mobility option defined in this
   specification is for use in PBU and PBA messages.  This option is
   carried like any other mobility header option as specified in
   [RFC5213].  Therefore, it inherits security guidelines from
   [RFC5213].

   The LMA-UPA address provided within the LMA User Plane Address
   mobility option MUST be a valid address under the administrative
   control associated with the LMA functional block.

   If the LMA-UP and the LMA-CP functions are hosted in different
   entities, any control messages between these two entities containing
   the LMA User Plane Address mobility option MUST be protected by
   IPsec.

8.  Acknowledgements

   The authors of this document thank the NetExt Working Group for the
   valuable feedback to different versions of this specification.  In
   particular the authors want to thank John Kaippallimalil, Sridhar
   Bhaskaran, Nirav Salot, Bruno Landais, Brian Carpenter, Pete Resnick,
   Stephen Farrell and Brian Haberman for their valuable comments and
   suggestions to improve this specification.

9.  References

9.1.  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.

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9.2.  Informative References

   [I-D.matsushima-stateless-uplane-vepc]
              Matsushima, S. and R. Wakikawa, "Stateless user-plane
              architecture for virtualized EPC (vEPC)",
              draft-matsushima-stateless-uplane-vepc-03 (work in
              progress), July 2014.

   [I-D.wakikawa-req-mobile-cp-separation]
              Wakikawa, R., Matsushima, S., Patil, B., Chen, B., DJ, D.,
              and H. Deng, "Requirements and use cases for separating
              control and user planes in mobile network architectures",
              draft-wakikawa-req-mobile-cp-separation-00 (work in
              progress), November 2013.

   [OpenFlow-Spec-v1.4.0]
              Open Networking Foundation, "OpenFlow Switch
              Specification", 2013.

   [RFC1701]  Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
              Routing Encapsulation (GRE)", RFC 1701, October 1994.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, December 1998.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213, October 2005.

   [RFC5810]  Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
              W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
              Control Element Separation (ForCES) Protocol
              Specification", RFC 5810, March 2010.

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [RFC6459]  Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
              Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, January 2012.

   [RFC6463]  Korhonen, J., Gundavelli, S., Yokota, H., and X. Cui,
              "Runtime Local Mobility Anchor (LMA) Assignment Support
              for Proxy Mobile IPv6", RFC 6463, February 2012.

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Authors' Addresses

   Ryuji Wakikawa
   Softbank Mobile
   1-9-1,Higashi-Shimbashi,Minato-Ku
   Tokyo  105-7322
   Japan

   Email: ryuji.wakikawa@gmail.com

   Rajesh S. Pazhyannur
   Cisco
   170 West Tasman Drive
   San Jose, CA 95134,
   USA

   Email: rpazhyan@cisco.com

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

   Email: sgundave@cisco.com

   Charles E. Perkins
   Futurewei Inc.
   2330 Central Expressway
   Santa Clara, CA 95050,
   USA

   Email: charliep@computer.org

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