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Versions: (draft-gundavelli-mip4-multiple-tunnel-support) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RFC 7629

Mobility for IPv4 Working Group                       S. Gundavelli, Ed.
Internet-Draft                                                  K. Leung
Intended status: Experimental                                      Cisco
Expires: October 21, 2015                                    G. Tsirtsis
                                                                Qualcomm
                                                             A. Petrescu
                                                                CEA LIST
                                                          April 19, 2015


                   Flow Binding Support for Mobile IP
             draft-ietf-mip4-multiple-tunnel-support-12.txt

Abstract

   This specification defines extensions to Mobile IP protocol for
   allowing a mobile node with multiple interfaces to register a care-of
   address for each of its network interfaces and to simultaneously
   establish multiple IP tunnels with its home agent.  This essentially
   allows the mobile node to utilize all the available network
   interfaces and build an higher aggregated logical pipe with its home
   agent for its home address traffic.  Furthermore, these extensions
   also allow the mobile node and the home agent to negotiate IP traffic
   flow policies for binding individual flows with the registered
   care-of addresses.

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
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 21, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   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  . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Example Call Flow  . . . . . . . . . . . . . . . . . . . .  6
   4.  Message Extensions . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Multipath Extension  . . . . . . . . . . . . . . . . . . .  7
     4.2.  Flow-Binding Extension . . . . . . . . . . . . . . . . . .  9
     4.3.  New Error Codes for Registration Reply . . . . . . . . . . 12
   5.  Protocol Operation . . . . . . . . . . . . . . . . . . . . . . 12
     5.1.  Mobile Node Considerations . . . . . . . . . . . . . . . . 12
     5.2.  Home Agent Considerations  . . . . . . . . . . . . . . . . 14
   6.  Routing Considerations . . . . . . . . . . . . . . . . . . . . 14
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   9.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 16
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 17
     11.2. Informative References . . . . . . . . . . . . . . . . . . 17


















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1.  Introduction

   With the ubiquitous availability of wireless networks based on
   different access technology types, mobile devices are now equipped
   with multiple wireless interfaces and have the ability to connect to
   the network using any of those interfaces.  For example, most mobile
   devices are equipped with Wi-Fi and LTE interfaces.  In many
   deployments, it is desirable for a mobile node to leverage all the
   available network interfaces and have IP mobility support for its IP
   flows.

   The operation defined in the Mobile IP Protocol [RFC5944], allows a
   mobile node to continue to use its home address as it moves around
   the internet.  Based on the mode of operation, there will be a IP
   tunnel that will be established between the home agent [RFC5944] and
   the mobile node [RFC5944], or between the home agent and the foreign
   agent [RFC5944] where the mobile node is attached.  In both of these
   modes, there will only be one interface on the mobile node that is
   receiving the IP traffic from the home agent.  This approach of using
   a single access-interface for routing all mobile node's traffic is
   not efficient and so there is a need to extend Mobile IP to
   concurrently use multiple access-interfaces for routing the mobile
   node's IP traffic.  The goal is for efficient use of all the
   available access links to obtain higher aggregated bandwidth for the
   tunneled traffic between the home agent and the mobile node.

   This specification defines extensions to Mobile IPv4 protocol for
   allowing a mobile node with multiple interfaces to register a care-of
   address for each of its network interfaces and to simultaneously
   leverage all access links for the mobile node's IP traffic.
   Furthermore, this specification also defines extensions to allow the
   mobile node and the home agent to optionally negotiate IP flow
   policies for binding individual IP flows with the registered care-of
   addresses.

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

   All the mobility related terms used in this document are to be
   interpreted as defined in [RFC5944] and [RFC3753].  In addition this
   document uses the following terms.



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   Binding Identifier (BID)

      It is an identifier assigned to a mobile node's binding.  A
      binding defines an association between a mobile node's home
      address and its registered care-of address.  A mobile node, when
      it registers multiple bindings with its home agent, each using
      different care-of addresses, then each of those bindings are given
      a unique identifier.  Each of the binding identifier will have a
      unique value which will be different from the identifiers assigned
      to the mobile node's other bindings.

   Flow Identifier (FID)

      It is an identifier for a given IP flow, uniquely identified by
      source address, destination address, protocol type, source port,
      destination port, Security Parameter Index and other parameters as
      identified in [RFC6088].  In the context of this document, the IP
      flows associated with a mobile node are the IP flows using its
      home address.  For a mobile router, the IP flows also include the
      IP flows using the mobile network prefix [RFC6626].

3.  Overview

   The illustration below in Figure 1 is an example scenario where a
   mobile node is connected to WLAN, LTE and CDMA access networks.  The
   mobile node is configured with an home address, HoA_1, and has
   obtained the care-of addresses [RFC5944] CoA_1 from the WLAN network,
   CoA_2 from the LTE network and CoA_3 from the CDMA network.

   The mobile node using the extensions specified in this document
   registers all the three care-of addresses with its home agent.  The
   mobile node also establishes an IP tunnel with the home agent using
   each of its IP addresses; Resulting in three IP tunnels (Tunnel_1,
   Tunnel_2 and Tunnel_3) between the mobile node and the home agent.
   Each of the tunnel represents a overlay routing path between the
   mobile node and the home agent and can be used for forwarding the
   mobile node's IP traffic.

   Furthermore, the extensions specified in this document allow the
   mobile node and the home agent to negotiate a IP flow policy.  The
   negotiated flow policy allow the mobile node and the home agent in
   determining the access network path for each of the mobile node's IP
   flows.








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   Flow_1 (SIP)
    |
    |Flow_2 (SSH)
    | |
    | |Flow_3 (HTTP)       _----_
    | | |         CoA_1  _(      )_   Tunnel_1
    | | |    .---=======(   Wi-Fi  )========\ Flow_1
    | | |    |           (_      _)          \
    | | |    |             '----'             \
    | | | +=====+          _----_              \  +=====+    _----_
    | | '-|     | CoA_2  _(      )_ Tunnel_2    \ |     |  _(      )_ --
    | '---| MN  |---====(   LTE    )=========-----| HA  |-( internet )--
    '-----|     |        (_      _)      Flow_3 / |     |  (_      _) --
          +=====+          '----'              /  +=====+    '----'
           | |             _----_             /
    HoA_1--' |    CoA_3  _(      )_ Tunnel_3 /
             .------====(   CDMA   )========/ Flow_2
                         (_      _)
                           '----'

       Figure 1: Mobile Node with multiple tunnels to the home agent

   The above table is an example of how the individual flows are bound
   to different care-of addresses registered with the home agent.

   +=========+===================+=====================================+
   | Flow Id |   Access Network  |           Description               |
   |  (FID)  |    Preferences    |                                     |
   +=========+===================+=====================================+
   | Flow_1  | Tunnel_1 / CoA_1  | All SIP Flows over Wi-Fi (preferred)|
   |         | Tunnel_2 / CoA_2  | If Wi-Fi is not available, use LTE  |
   |         |       <DROP>      | If Wi-Fi and LTE access network are |
   |         |                   | not available, drop the flow        |
   +---------+-------------------+-------------------------------------+
   | Flow_3  | Tunnel_2 / CoA_2  | All HTTP Flows over LTE (Preferred) |
   |         |       <DROP>      | If LTE not available, drop the flow |
   +---------+-------------------+-------------------------------------+
   | Flow_2  | Tunnel_3 / CoA_3  | All SSH Flows over CDMA (Preferred) |
   |         | Tunnel_2 / CoA_2  | If CDMA not available, use LTE      |
   |         | Tunnel_1 / CoA_1  | If LTE not available, use Wi-Fi     |
   +---------+-------------------+-------------------------------------+


                 Figure 2: Example of a IP Traffic Policy







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3.1.  Example Call Flow

   Figure 3 is the call-flow for the example scenario where a mobile
   node is connected to WLAN and LTE access networks.

      +-------+          +-------+          +-------+          +-------+
      |   MN  |          | WLAN  |          |  LTE  |          |  HA   |
      |       |          |Network|          |Network|          |       |
      +-------+          +-------+          +-------+          +-------+
         |                   |                  |                  |

   * MIP RRQ is sent using the IP Address obtained from the WLAN Network

         |<--- (1) --------->|                  |                  |
         |                   |   RRQ (Multipath, Flow-Binding)     |
         |---- (2) ----------------------------------------------->|
         |                   |   RRP            |                  |
         |<--- (3) ------------------------------------------------|
         |              MIP Tunnel through WLAN Network            |
         |=====(4)===========*=====================================|


   * MIP RRQ is sent using the IP address obtained from the LTE Network

         |<--- (5) ---------------------------->|                  |
         |                   |  RRQ (Multipath, Flow-Binding)      |
         |---- (6) ----------------------------------------------->|
         |                   |  RRP             |                  |
         |<--- (7) ------------------------------------------------|
         |              MIP Tunnel through LTE Access              |
         |=====(8)==============================*==================|
         |                                                         |
         *                                                         *
   (Policy-based Routing Rule)               (Policy-based Routing Rule)


            Figure 3: Multipath Negotiation - Example Call Flow

   o  (1): The mobile node (MN) attaches to the WLAN network and obtains
      IP address configuration for its WLAN interface.

   o  (2)-(3): The mobile node sends a Registration Request (RRQ)
      [RFC5944] to the home agent through the WLAN network.  The message
      includes the Multipath Section 4.1 and Flow-Binding Section 4.2
      extensions.  The home agent upon accepting the request sends a
      Registration Reply (RRP) [RFC5944] with a value of (0 )in the Code
      field of the Registration Reply.




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   o  (4): The mobile node and the home agent establish a bi-direction
      IP tunnel over the WLAN network.

   o  (5): The mobile node attaches to LTE network and obtains IP
      address configuration from that network.

   o  (6)-(7): The mobile node sends a Registration Request to the home
      agent through the LTE network.  The message includes the Multipath
      and Flow-Binding extensions.  The Flow-Binding extension indicates
      that all HTTP flows need to be routed over WLAN network and if
      WLAN access is not available, they need be routed over other
      access networks.  The negotiated policy also requires all Voice
      related traffic flows to be routed over LTE network.  The home
      agent upon accepting the request sends a Registration Reply with a
      value of (0) in the Code field of the Registration Reply.

   o  (8): The mobile node and the home agent establish a bi-direction
      IP tunnel over the LTE network.  The negotiated traffic flow
      policy is applied.  Both the home agent and the mobile node route
      all the voice flows over the tunnel established through the LTE
      access network and HTTP flows over WLAN network.

4.  Message Extensions

   This specification defines the following new extensions to Mobile IP.

4.1.  Multipath Extension

   This extension is used for requesting multipath support.  It
   indicates that the sender is requesting the home agent to register
   the current care-of address listed in this Registration Request as
   one of the many care-addresses through which the mobile node can be
   reached.  It is also for carrying the information specific to the
   interface to which the care-of addresses that is being registered is
   bound.

   This extension is a non-skippable extension and MAY be added by the
   mobile node to the Registration Request message.  There MUST NOT be
   more than one instance of this extension present in the message.
   This extension MUST NOT be added by the home agent to the
   Registration Reply.

   This extension should be protected using the Mobile-Home
   Authentication extension [RFC5944].  As specified in Section 3.2 and
   Section 3.6.1.3 of [RFC5944], the mobile node MUST place this
   Extension before the Mobile-Home Authentication Extension in the
   registration messages, so that this extension is integrity protected.




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   The format of this extension is as shown below.  It adheres to the
   long extension format described in [RFC5944].

        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      |  Sub-Type     |           Length              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    If-ATT     |   If-Label    |   Binding-Id  |B|O|  Reserved |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                       Figure 4: Multipath Extension



      Type

         Type: Multipath-Extension-Type (<IANA-1>)

      Length

         The length of the extension in octets, excluding Type, Sub-Type
         and Length fields.  This field MUST be set to value of 4.

      Sub-Type

         This field MUST be set to a value of 1 (Multipath Extension).

      Interface Access-Technology Type (If-ATT)

         This 8-bit field identifies the Access-Technology type of the
         interface through which the mobile node is connected.  The
         permitted values for this are from the Access Technology Type
         registry defined in [RFC5213].

      Interface Label (If-Label)

         This 8-bit field represents the interface label represented as
         an unsigned integer.  The mobile node identifies the label for
         each of the interfaces through which it registers a CoA with
         the home agent.  When using static traffic flow policies on the
         mobile node and the home agent, the label can be used for
         indexing forwarding policies.  For example, the operator may
         have a policy which binds an IP Flow "F1" to any interface with
         label "Blue".  When a registration through an interface
         matching Label "Blue" gets activated, the home agent and the
         mobile node establish an IP tunnel and the tunnel is marked



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         with that label.  Both the home agent and the mobile node
         generate traffic rule for forwarding IP flow traffic "F1"
         through mobile IP tunnel matching Label "Blue".  The permitted
         values for If-Label are 1 through 255.

      Binding-Identifier (BID)

         This 8-bit field is used for carrying the binding identifier.
         It uniquely identifies a specific binding of the mobile node,
         associated with this registration request.  Each binding
         identifier is represented as an unsigned integer.  The
         permitted values are 1 through 254.  The BID value of 0 and 255
         are reserved.

      Bulk Re-registration Flag (B)

         The (B) flag, if set to a value of (1), notifies the home agent
         to update the binding lifetime of all the mobile node's
         bindings, upon accepting this request.  The (B) flag MUST NOT
         be set to a value of (1), if the value of the Registration
         Overwrite Flag (O) flag is set to a value of (1).

      Registration Overwrite (O)

         The (O) flag, if set to a value of (1), notifies the home agent
         that upon accepting this request, it should replace all of the
         mobile node's existing bindings with the new binding that will
         be created upon accepting this request.  The (O) flag MUST NOT
         be set to a value of (1), if the value of the Bulk Re-
         registration Flag (B) is set to a value of (1).  This flag MUST
         be set to a value of (0), in de-registration requests.

      Reserved (R)

         This 6-bit field is unused for now.  The value MUST be
         initialized to (0) by the sender and MUST be ignored by the
         receiver.

4.2.  Flow-Binding Extension

   This extension contains information that can be used by the mobile
   node and the home agent for binding mobile node's IP flows to a
   specific multipath registration.  There can be more than one instance
   of this extension present in the message.

   This extension is a non-skippable extension and MAY be added to the
   Registration Request by the mobile node, or by the home agent to the
   Registration Reply.



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   This extension should be protected by Mobile-Home Authentication
   extension [RFC5944].  As specified in Section 3.2 and Section 3.6.1.3
   of [RFC5944], the mobile node MUST place this Extension before the
   Mobile-Home Authentication Extension in the registration messages, so
   that this extension is integrity protected.

   The format of this extension is as shown below.  It adheres to the
   long extension format described in [RFC5944].

        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      |  Sub-Type     |           Length              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Action     |  BID Count    |        ...   BID List   ...   ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   TS Format   |             Traffic Selector                  ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 5: Flow-Binding Extension



      Type

         Type: Multipath-Extension-Type (<IANA-1>)

      Sub-Type

         This field MUST be set to a value of 2 (Flow-Binding
         Extension).

      Length

         The length of the extension in octets, excluding Type, Sub-Type
         and Length fields.

      Action

         Action field identifies the traffic rule that needs to be
         enforced.  Following are the possible values.










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   +---------+-------+-------------------------------------------------+
   |  Action | Value | Description                                     |
   +---------+-------+-------------------------------------------------+
   |  DROP   |   0   | Drop matching packets. A filter rule            |
   |         |       | indicating a drop action MUST include a single  |
   |         |       | BID byte, the value of which MAY be set to 255  |
   |         |       | by the sender and the value of which SHOULD be  |
   |         |       | ignored by the receiver.                        |
   +---------+-------+-------------------------------------------------+
   | FORWARD |   1   | Forward matching packets to the 1st BID in the  |
   |         |       | list of BIDs the filter rule is pointing to.    |
   |         |       | If the 1st BID becomes invalid (i.e., the       |
   |         |       | corresponding CoA is deregistered) use the next |
   |         |       | BID in the list.                                |
   +---------+-------+-------------------------------------------------+


                 Figure 6: Action Rules for the Traffic Selector

      BID Count

         Total number of binding identifiers that follow this field.
         Permitted value for this field are 1 through 8; Each binding
         identifier is represented as an unsigned integer in a single
         octet field.  There is no delimiter between two binding
         identifier values, they are spaced consecutively.

      TS Format

         An 8-bit unsigned integer indicating the Traffic Selector
         Format.  Value (0) is reserved and MUST NOT be used.  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], and when the value of TS Format field is set to (2),
         the format that follows is the IPv6 Binary Traffic Selector
         specified in section 3.2 of [RFC6088].  The IPv6 traffic
         selectors are only relevant when the mobile node registers IPv6
         prefixes per [RFC5454].

      Traffic Selector

         A variable-length opaque field for including the traffic
         specification identified by the TS format field.  It identifies
         the traffic selectors for matching the IP traffic and binding
         them to specific binding identifiers.






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4.3.  New Error Codes for Registration Reply

   This document defines the following error code values for use by the
   home agent in the Code field of the Registration Reply.

   MULTIPATH_NOT_ALLOWED (Multipath Support not allowed for this mobile
   node): <IANA-3>

   INVALID_FB_IDENTIFIER (Invalid Flow Binding Identifier): <IANA-4>

5.  Protocol Operation

5.1.  Mobile Node Considerations

   o  The mobile node should register a care-of address for each of the
      connected interfaces that it wishes to register with the home
      agent.  It can do so by sending a Registration Request to the home
      agent through each of those interfaces.

   o  Each of the Registration Requests that is sent includes the
      care-of address of the respective interface.  The Registration
      Request has to be routed through the specific interface for which
      the registration is sough for.  Some of these interfaces may be
      connected to networks with a configured foreign agent on the link
      and in such foreign agent based registrations, the care-of address
      will be the IP address of the foreign agent.

   o  A Multipath extension (Section 4.1) reflecting the interface
      parameters are present in each of the Registration Requests.  This
      serves as an indication to the home agent that the Registration
      Request is a Multipath registration and the home agent will have
      to register this care-of address as one of the many care-of
      addresses through which the mobile node's home address is
      reachable.

   o  If the mobile node is configured to exchange IP flow policy to the
      home agent, then the Flow-Binding extension (Section 4.2)
      reflecting the flow policy can be included in the message.
      Otherwise, the Flow-Binding extension will not be included.

   o  The mobile node on receiving a Registration Reply with the code
      value set to MULTIPATH_NOT_ALLOWED, MAY choose to register without
      the Multipath extension specified in this document.  This implies
      the home agent has not enabled multipath support for this mobile
      node and hence multipath support MUST be disabled on the mobile
      node.





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   o  The mobile node on receiving a Registration Reply with the code
      value set to INVALID_FB_IDENTIFIER, MUST re-register that specific
      binding with the home agent.

   o  The mobile node at any time can extend the lifetime of a specific
      care-of address registration by sending a Registration Request to
      the home agent with a new lifetime value.  The message MUST be
      sent as the initial multipath registration and must be routed
      through that specific interface.  The message MUST include the
      Multipath extension (Section 4.1) with the value in the Binding-Id
      field set to the binding identifier assigned to that binding.
      Alternatively, the home agent can send a single Registration
      Request with the Bulk Re-registration Flag (B) set to a value of
      (1).  This serves as a request to the home agent to update the
      registration lifetime of all the mobile node's registrations.

   o  The mobile node at any time can de-register a specific care-of
      address by sending a Registration Request to the home agent with a
      lifetime value of (0).  The message must include the Multipath
      extension (Section 4.1) with the value in the Binding-Id field set
      to the binding identifier assigned to that binding Alternatively,
      the home agent can send a single Registration Request with the
      Bulk Re-registration Flag (B) set to a value of (1) and a lifetime
      value of (0).  This serves as a request to the home agent to
      consider this request as a request to de-register all the mobile
      node's care-of addresses.

   o  The mobile node at any time can update the parameters of a
      specific registration by sending a Registration Request to the
      home agent.  This includes change of care-of address associated
      with a previously registered interface.  The message must be sent
      as the initial multipath registration and must be routed through
      that specific interface.  The message must include the Multipath
      extension (Section 4.1) with the value in the Binding-Id field set
      to the binding identifier assigned to that binding and the
      Overwrite Flag (O) flag MUST set to a value of (1).

   o  The mobile node on receiving a Registration Reply with the code
      value set to 0 (registration accepted), will establish a mobile IP
      tunnel to the home agent using that care-of address.  When using
      foreign agent care-of address, the tunnel is between the home
      agent and the foreign agent.  The tunnel encapsulation type and
      any other parameters are based on the registration for that path.
      If there is also an exchange of flow policy between the mobile
      node and the home agent, with the use of Flow-Binding extensions
      then the mobile node must set up the forwarding plane that matches
      the flow policy.




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5.2.  Home Agent Considerations

   The home agent upon receiving a Registration Request from a mobile
   node with a Multipath extension, should check if the mobile node is
   authorized for multipath support.  If multipath support is not
   enabled, the home agent MUST reject the request with a registration
   reply and with the code set to MULTIPATH_NOT_ALLOWED.

   If the received Registration Request includes a Multipath extension
   and additionally has the Bulk Re-registration (B) flag set to a value
   of (1), then the home agent MUST extend the lifetime of all the
   bindings associated with that mobile node.

   The home agent upon receipt of a Registration Request with the Flow-
   Binding Extension must process the extension and upon accepting the
   flow policy must set up the forwarding plane that matches the flow
   policy.  If the home agent cannot identify any of the binding
   identifiers then it MUST reject the request with a Registration Reply
   and with the code set to INVALID_FB_IDENTIFIER.

   If the received Registration Request includes a Multipath extension
   and additionally has the Registration Overwrite (O) flag set to a
   value of (1), then the home agent MUST consider this as a request to
   replace all other mobile node's bindings with just one binding and
   that is the binding associated with this request.

6.  Routing Considerations

   When multipath registration is enabled for a mobility node, there
   will be multiple mobile IP tunnels established between a mobile node
   and its home agent.  These mobile IP tunnels appear to the forwarding
   plane of the mobile node as equal-cost, point-to-point links.

   If there is also an exchange of traffic flow policy between the
   mobile node and the home agent, with the use of Flow-Binding
   extensions (Section 4.2), then the mobile node's IP traffic can be
   routed by the mobility entities as per the negotiated flow policy.
   However, if multipath is enabled for a mobility session, without the
   use of any flow policy exchange, then both the mobile node and the
   home agent are required to have a pre-configured static flow policy.
   The specific details on the semantics of this static flow policy is
   outside the scope of this document.

   In the absence of any established traffic flow policies, most IP
   hosts support two alternative traffic load-balancing schemes, Per-
   flow and Per-packet load balancing [RFC2991].  These load balancing
   schemes allow the forwarding plane to evenly distribute traffic based
   on the criteria of either a per-packet or on a per-flow basis, across



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   all the available equal-cost links through which a destination can be
   reached.  The default forwarding behavior of per-flow load balancing
   will ensure a given flow always takes the same path and will
   eliminate any packet re-ordering issues and that is critical for
   delay sensitive traffic.  Whereas the per-destination load balancing
   scheme leverages all the paths much more affectively, but with the
   potential issue of packet re-ordering on the receiver end.  This
   issue will be specially magnified when the access links have very
   different forwarding characteristics.  A host can choose to enable
   any of these approaches.  Therefore, this specification recommends
   the use of per-flow load balancing.

7.  IANA Considerations

   This document requires the following IANA actions.

   o  Action-1: This specification defines two new Mobile IP extensions,
      Multipath extension and Flow-Binding extension.  The format of the
      Multipath extension is described in Section 4.1 and the format of
      the Flow-Binding extension is described in Section 4.2.  Both of
      these extensions are non-skippable extensions to the Mobile IPv4
      header in accordance to the long extension format of [RFC5944].
      Both of these extensions use a common Type value, Multipath-
      Extension-Type (<IANA-1>) but are identified using different Sub-
      Type values.  The type value <IANA-1> for these extension needs to
      be allocated from the registry, "Extensions to Mobile IP
      Registration Messages", at the URL, <http://www.iana.org/
      assignments/mobileip-numbers/mobileip-numbers.xhtml>.  RFC Editor:
      Please replace <IANA-1> in Section 4.1 and in Section 4.2 with the
      assigned value and update these sections accordingly.

   o  Action-2: This specification defines a new message sub-type space,
      Multipath Extension sub-type.  This field is described in
      Section 4.1.  The values for this sub-type field needs to be
      managed by IANA, under the Registry, Multipath Extension Sub-type
      Registry.  This specification reserves the following type values.
      Approval of new Multipath Extension sub-type values are to be made
      through IANA Expert Review.


      +=========================================================+
      |  0    | Reserved                                        |
      +=========================================================+
      |  1    | Multipath Extension                             |
      +=========================================================+
      |  2    | Flow-Binding Extension                          |
      +=========================================================+




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   o  Action-3: This document defines new status code values,
      MULTIPATH_NOT_ALLOWED (<IANA-3>), INVALID_FB_IDENTIFIER (<IANA-4>)
      for use by the home agent in the Code field of the Registration
      Reply, as described in Section 4.3.  This value needs to be
      assigned from the "Registration denied by the home agent" registry
      at <http://www.iana.org/assignments/mobility-parameters>.  The
      allocated value has to be greater than 127.  RFC Editor: Please
      replace <IANA-3> in Section 4.3 with the assigned value and update
      this section accordingly.

8.  Security Considerations

   This specification allows a mobile node to establish multiple Mobile
   IP tunnels with its home agent, by registering a care-of address for
   each of its active roaming interfaces.  This essentially allows the
   mobile node's IP traffic to be routed through any of the tunnel paths
   based on a static or a dynamically negotiated flow policy.  This new
   capability has no impact on the protocol security.  Furthermore, this
   specification defines two new Mobile IP extensions, Multipath
   extension and the Flow-Binding extension.  These extensions are
   specified to be included in Mobile IP control messages, which are
   authenticated and integrity protected as described in [RFC5944].
   Therefore, this specification does not weaken the security of Mobile
   IP Protocol, and does not introduce any new security vulnerabilities.

9.  Contributors

   This document reflects discussions and contributions from the
   following people:

   Ahmad Muhanna

      asmuhanna@yahoo.com

   Srinivasa Kanduru

      skanduru@gmail.com

   Vince Park

      vpark@qualcomm.com

   Hesham Soliman

      hesham@elevatemobile.com






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10.  Acknowledgements

   We like to thank Qin Wu, Shahriar Rahman, Mohana Jeyatharan, Yungui
   Wang, Hui Deng Behcet Sarikaya, Jouni Korhonen, Michaela Vanderveen,
   Antti Makela, Charles Perkins, Pierrick Siette for their review and
   comments on this draft.

11.  References

11.1.  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.

   [RFC5944]  Perkins, C., "IP Mobility Support for IPv4, Revised",
              RFC 5944, November 2010.

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

11.2.  Informative References

   [RFC2991]  Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
              Multicast Next-Hop Selection", RFC 2991, November 2000.

   [RFC3753]  Manner, J. and M. Kojo, "Mobility Related Terminology",
              RFC 3753, June 2004.

   [RFC5454]  Tsirtsis, G., Park, V., and H. Soliman, "Dual-Stack Mobile
              IPv4", RFC 5454, March 2009.

   [RFC6626]  Tsirtsis, G., Park, V., Narayanan, V., and K. Leung,
              "Dynamic Prefix Allocation for Network Mobility for Mobile
              IPv4 (NEMOv4)", RFC 6626, May 2012.













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Authors' Addresses

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

   EMail: sgundave@cisco.com


   Kent Leung
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   EMail: kleung@cisco.com


   George Tsirtsis
   Qualcomm

   EMail: tsirtsis@qualcomm.com


   Alexandru Petrescu
   CEA LIST
   Communicating Systems Laboratory, Point Courrier 94
   Gif-sur-Yvette  F-91191
   France

   Phone: +33 169089223
   EMail: alexandru.petrescu@cea.fr

















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