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Internet Engineering Task Force (IETF)                S. Gundavelli, Ed.Request for Comments: 7629                                      K. LeungCategory: Experimental                                             CiscoISSN: 2070-1721                                              G. Tsirtsis                                                                Qualcomm                                                             A. Petrescu                                                               CEA, LIST                                                             August 2015Flow-Binding Support for Mobile IPAbstract   This specification defines extensions to the 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 a 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 document is not an Internet Standards Track specification; it is   published for examination, experimental implementation, and   evaluation.   This document defines an Experimental Protocol for the Internet   community.  This document is a product of the Internet Engineering   Task Force (IETF).  It represents the consensus of the IETF   community.  It has received public review and has been approved for   publication by the Internet Engineering Steering Group (IESG).  Not   all documents approved by the IESG are a candidate for any level of   Internet Standard; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7629.Gundavelli, et al.            Experimental                      [Page 1]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015Copyright Notice   Copyright (c) 2015 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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 Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .32.  Conventions and Terminology . . . . . . . . . . . . . . . . .32.1.  Conventions . . . . . . . . . . . . . . . . . . . . . . .32.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .33.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .43.1.  Example Call Flow . . . . . . . . . . . . . . . . . . . .64.  Message Extensions  . . . . . . . . . . . . . . . . . . . . .74.1.  Multipath Extension . . . . . . . . . . . . . . . . . . .74.2.  Flow-Binding Extension  . . . . . . . . . . . . . . . . .94.3.  New Error Codes for Registration Reply  . . . . . . . . .125.  Protocol Operation  . . . . . . . . . . . . . . . . . . . . .125.1.  Mobile Node Considerations  . . . . . . . . . . . . . . .125.2.  Home Agent Considerations . . . . . . . . . . . . . . . .146.  Routing Considerations  . . . . . . . . . . . . . . . . . . .147.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .158.  Security Considerations . . . . . . . . . . . . . . . . . . .169.  References  . . . . . . . . . . . . . . . . . . . . . . . . .179.1.  Normative References  . . . . . . . . . . . . . . . . . .179.2.  Informative References  . . . . . . . . . . . . . . . . .17   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .18   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .18   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .19Gundavelli, et al.            Experimental                      [Page 2]

RFC 7629           Flow-Binding Support for Mobile IP        August 20151.  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 (Long Term Evolution)   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 an IP   tunnel that will be established between the home agent and the mobile   node or between the home agent and the foreign agent where the mobile   node is attached; see [RFC5944].  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 Terminology2.1.  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 inRFC 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.Gundavelli, et al.            Experimental                      [Page 3]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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.  When a mobile node      registers multiple bindings with its home agent, each using a      different care-of address, then each of those bindings are given a      unique identifier.  Each of the binding identifiers will have a      unique value that 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 a home address, HoA_1, and has   obtained the following 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 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, which results in three IP tunnels   (Tunnel_1, Tunnel_2, and Tunnel_3) between the mobile node and the   home agent.  Each of the tunnels represents an overlay routing path   between the mobile node and the home agent and can be used for   forwarding the mobile node's IP traffic.   Furthermore, using the extensions specified in this document, the   mobile node and the home agent can negotiate an IP flow policy.  The   negotiated flow policy allows the mobile node and the home agent to   determine the access network path for each of the mobile node's IP   flows.Gundavelli, et al.            Experimental                      [Page 4]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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 (MN) with Multiple Tunnels                          to the Home Agent (HA)   The table below 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 networks 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 an IP Traffic PolicyGundavelli, et al.            Experimental                      [Page 5]

RFC 7629           Flow-Binding Support for Mobile IP        August 20153.1.  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 Network      |         |=====(8)==============================*==================|         |                                                         |         *                                                         *   (Policy-based Routing Rule)               (Policy-based Routing Rule)            Figure 3: Multipath Negotiation - Example Call Flow   o  (1): The mobile node attaches to the WLAN network and obtains the      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 the 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.Gundavelli, et al.            Experimental                      [Page 6]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   o  (4): The mobile node and the home agent establish a bidirectional      IP tunnel over the WLAN network.   o  (5): The mobile node attaches to the LTE network and obtains the      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 the Flow-Binding Extensions.  The Flow-Binding Extension      indicates that all HTTP flows need to be routed over the WLAN      network and if the WLAN access network 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 the 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 bidirectional      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 the HTTP flows over the 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-of 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 address 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 Sections3.2 and   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.Gundavelli, et al.            Experimental                      [Page 7]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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      |    Subtype    |           Length              |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       |    If-ATT     |   If-Label    |   Binding ID  |B|O|  Reserved |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                       Figure 4: Multipath Extension   Type      Type: Multipath-Extension-Type (154)   Subtype      This field MUST be set to a value of 1 (Multipath Extension).   Length      The length of the extension in octets, excluding Type, Subtype,      and Length fields.  This field MUST be set to a value of 4.   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 that binds      an IP flow "F1" to any interface with the label "Blue".  When a      registration through an interface matching the label "Blue" gets      activated, the home agent and the mobile node establish an IP      tunnel and the tunnel is marked with that label.  Both the home      agent and the mobile node generate traffic rules for forwarding IP      flow traffic "F1" through the mobile IP tunnel matching the label      "Blue".  The permitted values for If-Label are 1 through 255.Gundavelli, et al.            Experimental                      [Page 8]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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.   This extension should be protected by Mobile-Home Authentication   Extension [RFC5944].  As specified inSection 3.2 and 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.Gundavelli, et al.            Experimental                      [Page 9]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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      |    Subtype    |           Length              |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       |    Action     |  BID Count    |        ...   BID List   ...   ~       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       |   TS Format   |             Traffic Selector                  ~       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     Figure 5: Flow-Binding Extension   Type      Type: Multipath-Extension-Type (154)   Subtype      This field MUST be set to a value of 2 (Flow-Binding Extension).   Length      The length of the extension in octets, excluding Type, Subtype,      and Length fields.   Action      The Action field identifies the traffic rule that needs to be      enforced.  Following are the possible values.Gundavelli, et al.            Experimental                     [Page 10]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   +---------+-------+-------------------------------------------------+   |  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 first BID in the|   |         |       | list of BIDs the filter rule is pointing to.    |   |         |       | If the first BID becomes invalid (i.e., the     |   |         |       | corresponding CoA is de-registered), 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.  The      permitted values 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 (TS)      Format.  The value (0) is reserved and MUST NOT be used.  When the      value of the TS Format field is set to (1), the format that      follows is the IPv4 Binary Traffic Selector specified inSection 3.1 of [RFC6088], and when the value of the TS Format      field is set to (2), the format that follows is the IPv6 Binary      Traffic Selector specified inSection 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.Gundavelli, et al.            Experimental                     [Page 11]

RFC 7629           Flow-Binding Support for Mobile IP        August 20154.3.  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): 152   INVALID_FB_IDENTIFIER (Invalid Flow-Binding Identifier): 1535.  Protocol Operation5.1.  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 sought 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 is 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, upon 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.Gundavelli, et al.            Experimental                     [Page 12]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   o  The mobile node, upon 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 can, at any time, 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 can, at any time, update the parameters of a      specific registration by sending a Registration Request to the      home agent.  This includes a 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 be set to a value of (1).   o  The mobile node, upon 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 a      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.Gundavelli, et al.            Experimental                     [Page 13]

RFC 7629           Flow-Binding Support for Mobile IP        August 20155.2.  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 are   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 on   either a per-packet or per-flow basis, across all the availableGundavelli, et al.            Experimental                     [Page 14]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015   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 effectively 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   Per this document, the following IANA actions have been completed.   o  Action 1: This specification defines two new Mobile IP extensions,      the Multipath Extension and the Flow-Binding Extension.  The      format of the Multipath Extension is described inSection 4.1, and      the format of the Flow-Binding Extension is described inSection 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 (154), but are identified      using different Subtype values.  The Type value 154 for these      extensions has been allocated from the "Extensions to Mobile IP      Registration Messages" registry at the URL      <http://www.iana.org/assignments/mobileip-numbers>.  The field      "Permitted for Notification Messages" for this extension MUST be      set to "N".   o  Action 2: This specification defines a new message subtype space,      Multipath Extension subtype.  This field is described inSection 4.1.  The values for this subtype field are managed by      IANA under the "Multipath Extension subtypes (Value 154)"      registry.  This specification reserves the following Type values.      Approvals of new Multipath Extension subtype values are to be made      through IANA Expert Review [RFC5226].Gundavelli, et al.            Experimental                     [Page 15]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015      +=========================================================+      |  0    | Reserved                                        |      +=========================================================+      |  1    | Multipath Extension                             |      +=========================================================+      |  2    | Flow-Binding Extension                          |      +=========================================================+      |       |                                                 |      ~ 3-254 | Unassigned                                      ~      |       |                                                 |      +=========================================================+      |  255  | Reserved                                        |      +=========================================================+   o  Action 3: This document defines new status code values,      MULTIPATH_NOT_ALLOWED (152) and INVALID_FB_IDENTIFIER (153), for      use by the home agent in the Code field of the Registration Reply,      as described inSection 4.3.  These values have been assigned from      the "Registration denied by the home agent" registry at      <http://www.iana.org/assignments/mobileip-numbers>.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, the 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 the   Mobile IP protocol and does not introduce any new security   vulnerabilities.Gundavelli, et al.            Experimental                     [Page 16]

RFC 7629           Flow-Binding Support for Mobile IP        August 20159.  References9.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",RFC 5213, DOI 10.17487/RFC5213, August 2008,              <http://www.rfc-editor.org/info/rfc5213>.   [RFC5944]  Perkins, C., Ed., "IP Mobility Support for IPv4, Revised",RFC 5944, DOI 10.17487/RFC5944, November 2010,              <http://www.rfc-editor.org/info/rfc5944>.   [RFC6088]  Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont,              "Traffic Selectors for Flow Bindings",RFC 6088,              DOI 10.17487/RFC6088, January 2011,              <http://www.rfc-editor.org/info/rfc6088>.9.2.  Informative References   [RFC2991]  Thaler, D. and C. Hopps, "Multipath Issues in Unicast and              Multicast Next-Hop Selection",RFC 2991,              DOI 10.17487/RFC2991, November 2000,              <http://www.rfc-editor.org/info/rfc2991>.   [RFC3753]  Manner, J., Ed. and M. Kojo, Ed., "Mobility Related              Terminology",RFC 3753, DOI 10.17487/RFC3753, June 2004,              <http://www.rfc-editor.org/info/rfc3753>.   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              DOI 10.17487/RFC5226, May 2008,              <http://www.rfc-editor.org/info/rfc5226>.   [RFC5454]  Tsirtsis, G., Park, V., and H. Soliman, "Dual-Stack Mobile              IPv4",RFC 5454, DOI 10.17487/RFC5454, March 2009,              <http://www.rfc-editor.org/info/rfc5454>.   [RFC6626]  Tsirtsis, G., Park, V., Narayanan, V., and K. Leung,              "Dynamic Prefix Allocation for Network Mobility for Mobile              IPv4 (NEMOv4)",RFC 6626, DOI 10.17487/RFC6626, May 2012,              <http://www.rfc-editor.org/info/rfc6626>.Gundavelli, et al.            Experimental                     [Page 17]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015Acknowledgements   We would like to thank Qin Wu, Shahriar Rahman, Mohana Jeyatharan,   Yungui Wang, Hui Deng Behcet Sarikaya, Jouni Korhonen, Michaela   Vanderveen, Antti Makela, Charles Perkins, Pierrick Seite, Vijay   Gurbani, Barry Leiba, Henrik Levkowetz, Pete McCann, and Brian   Haberman for their review and comments on this document.Contributors   This document reflects discussions and contributions from the   following people:   Ahmad Muhanna   Email: asmuhanna@yahoo.com   Srinivasa Kanduru   Email: skanduru@gmail.com   Vince Park   Email: vpark@qualcomm.com   Hesham Soliman   Email: hesham@elevatemobile.comGundavelli, et al.            Experimental                     [Page 18]

RFC 7629           Flow-Binding Support for Mobile IP        August 2015Authors' Addresses   Sri Gundavelli (editor)   Cisco   170 West Tasman Drive   San Jose, CA  95134   United States   Email: sgundave@cisco.com   Kent Leung   Cisco   170 West Tasman Drive   San Jose, CA  95134   United States   Email: kleung@cisco.com   George Tsirtsis   Qualcomm   Email: tsirtsis@qualcomm.com   Alexandre Petrescu   CEA, LIST   CEA Saclay   Gif-sur-Yvette , Ile-de-France  91191   France   Phone: +33169089223   Email: alexandre.petrescu@cea.frGundavelli, et al.            Experimental                     [Page 19]