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RFC 7077 - Update Notifications for Proxy Mobile IPv6


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Internet Engineering Task Force (IETF)                       S. Krishnan
Request for Comments: 7077                                      Ericsson
Category: Standards Track                                  S. Gundavelli
ISSN: 2070-1721                                                    Cisco
                                                              M. Liebsch
                                                                     NEC
                                                               H. Yokota
                                                                    KDDI
                                                             J. Korhonen
                                                                Broadcom
                                                           November 2013

               Update Notifications for Proxy Mobile IPv6

Abstract

   This document specifies protocol enhancements for allowing the local
   mobility anchor in a Proxy Mobile IPv6 domain to asynchronously
   notify the mobile access gateway about changes related to a mobility
   session.  These Update Notification messages are exchanged using a
   new Mobility Header message type specifically designed for this
   purpose.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7077.

Copyright Notice

   Copyright (c) 2013 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
   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 .....................................4
      2.1. Conventions ................................................4
      2.2. Terminology ................................................4
   3. Notification Message - Usage Examples ...........................4
   4. Message Formats .................................................5
      4.1. Update Notification (UPN) ..................................5
      4.2. Update Notification Acknowledgement (UPA) ..................7
   5. LMA Considerations ..............................................9
      5.1. Constructing the Update Notification Message ..............10
      5.2. Receiving the Update Notification Acknowledgement
           Message ...................................................11
   6. MAG Considerations .............................................12
      6.1. Receiving the Update Notification Message .................12
      6.2. Constructing the Update Notification Acknowledgement
           Message ...................................................15
   7. Protocol Configuration Variables ...............................16
   8. Security Considerations ........................................16
   9. Acknowledgements ...............................................17
   10. IANA Considerations ...........................................17
   11. References ....................................................19
      11.1. Normative References .....................................19
      11.2. Informative References ...................................19

1.  Introduction

   In some situations, there is a need for the local mobility anchor
   (LMA) to send asynchronous notification messages to the mobile access
   gateway (MAG) in the course of a mobility session.  These situations
   include changes to mobility session parameters and policy parameters.
   In this context, "Asynchronous messages" is used to mean messages
   that are not synchronous with the Proxy Binding Update and Proxy
   Binding Acknowledgement messages of the base Proxy Mobile IPv6
   specification [RFC5213].  The base Proxy Mobile IPv6 specification
   does not have a provision for sending unsolicited Update Notification
   messages from the local mobility anchor to the mobile access gateway.

   Proxy Mobile IPv6 [RFC5213] is a network-based mobility management
   protocol.  It is designed to provide IP mobility management support
   to a mobile node without requiring the participation of the mobile
   node in any IP mobility-related signaling.  The protocol defines two
   mobility management entities: the LMA and the MAG.  These entities
   are responsible for managing IP mobility management support for a
   mobile node in a Proxy Mobile IPv6 domain.  The setup of the mobility
   session is initiated by the mobile access gateway by sending a Proxy
   Binding Update message and acknowledged by the local mobility anchor
   in the Proxy Binding Acknowledgement message.  Once the mobility
   session is set up, currently there is no mechanism for the local
   mobility anchor to inform the mobile access gateway about changes to
   the mobility session or any parameters related to the mobility
   session.  However, there are mechanisms in the Proxy Mobile IPv6
   protocol that allow a local mobility anchor to send signaling
   messages to the mobile access gateway asynchronously, as defined in
   the Proxy Mobile IPv6 Heartbeat message [RFC5847] or in the Binding
   Revocation message [RFC5846], but these signaling messages are
   designed for a very specific purpose and are not sufficient for
   supporting a notification framework.

   One such scenario where such a mechanism is needed is when the local
   mobility anchor wants to inform the mobile access gateway that it
   needs to re-register the mobility session for a mobile node.  It is
   possible to achieve a similar effect by using a short lifetime for
   the mobility sessions, but in several networks this results in an
   unacceptable, and mostly unnecessary, increase in the signaling
   load and overhead.  A more suitable scenario would be to enable
   demand-based signaling from the local mobility anchor to one or more
   mobile access gateways.  Another example is when there is a change in
   a QoS policy [PMIPv6-QoS], an IP flow mobility policy
   [PMIPv6-FLOW-MOB], or an IPv4 traffic offload policy [RFC6909] for a
   mobility session.  In this case, the local mobility anchor wants to
   request that the mobile access gateway perform re-registration of the

   mobility session in order to update the policies associated with the
   mobility session of a mobile node.

   This document defines a new Mobility Header message for allowing the
   local mobility anchor to send notification messages to the mobile
   access gateway and a corresponding Mobility Header message for the
   mobile access gateway to acknowledge the notification message.  The
   purpose of the notification message is twofold: (1) to enable the
   local mobility anchor to notify the mobile access gateway about the
   updated session parameters and (2) to enable the local mobility
   anchor to request that the mobile access gateway renegotiate the
   session parameters.

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 the base Proxy Mobile IPv6 specifications
   [RFC5213] and [RFC5844].

3.  Notification Message - Usage Examples

   Use Case 1: Consider a use case where the local mobility anchor wants
   the mobile access gateway to re-register a specific mobility session.

   MN     MAG       LMA
   |------>|        |    1.  Mobile Node Attach
   |       |------->|    2.  Proxy Binding Update
   |       |<-------|    3.  Proxy Binding Acknowledgement
   |       |========|    4.  Tunnel/Route Setup
   |       |        |
   |       |<-------|    5.  Update Notification (FORCE-REREGISTRATION)
   |       |------->|    6.  Update Notification Acknowledgement
   |       |        |
   |       |------->|    7.  Proxy Binding Update
   |       |<-------|    8.  Proxy Binding Acknowledgement
   |       |        |

            Figure 1: Update Notification: FORCE-REREGISTRATION

   Use Case 2: Consider a use case where the local mobility anchor wants
   to notify the mobile access gateway of the updated session
   parameters, for example, an updated QoS profile or an updated IPv4
   offload policy.

   MN     MAG     LMA
   |------>|        |    1.  Mobile Node Attach
   |       |------->|    2.  Proxy Binding Update
   |       |<-------|    3.  Proxy Binding Acknowledgement
   |       |========|    4.  Tunnel/Route Setup
   |       |        |
   |       |<-------|    5.  Update Notification
   |       |        |           (UPDATE-SESSION-PARAMETERS)
   |       |------->|    6.  Update Notification Acknowledgement
   |       +        |    7.  MAG applies the new policy option
   |       |        |

         Figure 2: Update Notification: UPDATE-SESSION-PARAMETERS

4.  Message Formats

4.1.  Update Notification (UPN)

   The Update Notification is a Mobility Header message that has an MH
   Type value of 19.  It is used by the local mobility anchor to notify
   the mobile access gateway that some parameters related to the
   mobility session have changed.

   The format of the Update Notification message is as follows:

   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
                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                   |           Sequence #          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Notification Reason        |A|D|          Reserved         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 3: Update Notification Message

   Sequence Number
      This 16-bit unsigned integer is used by the local mobility anchor
      to match the received Update Notification Acknowledgement message
      with this Update Notification message.  This Sequence Number could
      be a random number and can be managed under the same variable used
      in Proxy Mobile IPv6 signaling messages [RFC5213].
      Implementations MUST ensure that there is no collision between the
      Sequence Numbers of all outstanding Update Notification messages
      at any time.

   Notification Reason
      This 16-bit unsigned integer indicates the Notification Reason
      code.  This code corresponds to the reason that the local mobility
      anchor sent the Update Notification to the mobile access gateway.
      This field does not contain any structure and MUST be treated as
      an enumeration.  The reason code can indicate a vendor-specific
      reason if the semantics of the Update Notification message are to
      be based on the attached vendor-specific options, not solely from
      the reason code.  These attached options can be deployment
      specific and are not specified in this document.  The following
      Notification Reason values are currently defined:

      (0) -     Reserved
                This value is currently reserved and cannot be used.

      (1) -     FORCE-REREGISTRATION
                Request to re-register the session by sending a Proxy
                Binding Update for the mobility session.

      (2) -     UPDATE-SESSION-PARAMETERS
                Request to apply the updated session parameters obtained
                from the message on the mobility session.

      (3) -     VENDOR-SPECIFIC-REASON
                This Notification Reason is for vendor-specific use.
                The processing rules are to be based on the
                Vendor-Specific Mobility option(s) [RFC5094] present in
                the message.

      (4) -     ANI-PARAMS-REQUESTED
                Request to send currently known Access Network
                Identifier (ANI) [RFC6757] parameters for the mobility
                session.

      (255) -   Reserved
                This value is currently reserved and cannot be used.

   Acknowledgement Requested Flag ((A) Flag)
      When this flag is set to a value of (1), it is an indication that
      the local mobility anchor is requesting that the mobile access
      gateway send an Update Notification Acknowledgement message.  When
      this flag is set to a value of (0), it is an indication that the
      local mobility anchor is not requesting any Update Notification
      Acknowledgement messages.

   Retransmit Flag ((D) Flag)
      When this flag is set to a value of (1), it is an indication that
      the message is a retransmitted message and has the same Sequence
      Number and other message contents as in the previously sent
      message.  The (D) flag is set for retransmitted request messages,
      to aid the reliable detection of duplicate requests at the
      receiver of the request message.  It is set when originating
      requests that have not yet been acknowledged, as an indication of
      a possible duplicate due to a retransmission.  This flag MUST be
      cleared when sending a request for the first time for a given
      Sequence Number; otherwise, the sender MUST set this flag.

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

   Mobility Options
      This variable-length field is of such length that the complete
      Mobility Header is an integer multiple of 8 octets long; the Pad1
      and PadN options [RFC6275] can be used for padding.  This field
      contains zero or more TLV-encoded mobility options.  Any of the
      Mobility Header options, including Vendor-Specific Mobility
      options [RFC5094], can be included here.  The receiver MUST ignore
      and skip any options that it does not understand.  These mobility
      options are used by the mobile access gateway to identify the
      specific binding for which the Update Notification message is
      sent.

4.2.  Update Notification Acknowledgement (UPA)

   The Update Notification Acknowledgement is a Mobility Header message
   that has an MH Type value of 20.  The mobile access gateway sends
   this message in order to acknowledge that it has received an Update
   Notification message with the (A) flag set and to indicate the status
   after processing the message.

   The format of the Update Notification Acknowledgement message is as
   follows:

   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
                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                   |           Sequence #          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Status Code |                   Reserved                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 4: Update Notification Acknowledgement Message

   Sequence Number
      This 16-bit unsigned integer is copied from the Update
      Notification message and is used for matching the Update
      Notification Acknowledgement message with the Update Notification
      message.

   Status Code
      This 8-bit unsigned integer indicates the status code and
      specifies the result of the processing of the Update Notification
      message.  Status codes between 0 and 127 signify successful
      processing of the Update Notification message, and codes between
      128 and 255 signify that an error occurred during processing of
      the Update Notification message.  The following status code values
      are currently defined:

      (0) -     SUCCESS
                The mobile access gateway successfully processed the
                received Update Notification message.

      (128) -   FAILED-TO-UPDATE-SESSION-PARAMETERS
                The mobile access gateway was not able to apply the
                session parameters sent by the local mobility anchor in
                the Update Notification message.

      (129) -   MISSING-VENDOR-SPECIFIC-OPTION
                The received Update Notification message does not have
                the required Vendor-Specific Mobility option(s) needed
                for handling the message.

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

   Mobility Options
      This variable-length field is of such length that the complete
      Mobility Header is an integer multiple of 8 octets long; the Pad1
      and PadN options [RFC6275] can be used for padding.  This field
      contains zero or more TLV-encoded mobility options.  Any of the
      Mobility Header options, including Vendor-Specific Mobility
      options [RFC5094], can be included here.  The receiver MUST ignore
      and skip any options that it does not understand.  These mobility
      options are used by the mobile access gateway to identify the
      specific binding for which the Update Notification Acknowledgement
      message is sent.

5.  LMA Considerations

   o  The local mobility anchor sends the Update Notification message in
      response to a condition that is specified in the Notification
      Reason field.  The Notification Reason field in the Update
      Notification message MUST be set to a specific value that
      identifies the reason for which the Update Notification message is
      being sent.  The Notification Reason, based on the chosen value,
      may require a specific action that the mobile access gateway needs
      to perform (for example, requiring re-registration of a mobility
      session).

   o  The Update Notification message MUST include either the Mobile
      Node Identifier option [RFC4283] or the Mobile Node Group
      Identifier option [RFC6602].

      *  If the Mobile Node Identifier option is present, it indicates
         that the Update Notification message is sent for that specific
         mobility session.

      *  If the Mobile Node Group Identifier option is present, it
         indicates that the Update Notification message is sent for the
         set of mobility sessions identified by the Group Identifier.
         The Group Identifier is negotiated as part of the initial Proxy
         Mobile IPv6 signaling.  If the Group Identifier is not
         negotiated in the initial Proxy Mobile IPv6 signaling, a value
         of (1) for the Group Identifier can always be used.  The Group
         Identifier value of (1) identifies all the mobility sessions
         established between that local mobility anchor and the mobile
         access gateway.

   o  The Update Notification message MAY contain a modified session
      parameter in the form of a mobility option (e.g., an IPv4 traffic
      offload option or a QoS option), so the mobile access gateway can
      apply them on the identified mobility session.

5.1.  Constructing the Update Notification Message

   The local mobility anchor, when sending the Update Notification
   message to the mobile access gateway, has to construct the message as
   specified below:

   o  For requesting an Acknowledgement message and an indication about
      the result of processing the message from the mobile access
      gateway for the Update Notification message, the (A) flag in the
      Update Notification message MUST be set to a value of (1);
      otherwise, it MUST be set to a value of (0).  However, if the
      Notification Reason is set to a value of (1)
      "FORCE-REREGISTRATION" or (4) "ANI-PARAMS-REQUESTED", then it is
      RECOMMENDED that the (A) flag be set to a value of (0).  For
      certain general notifications that are informational in nature,
      the local mobility anchor may choose not to request
      acknowledgement for the Update Notification message.

   o  The Sequence Number field of the message MUST be initialized to a
      random number and increased monotonically for subsequent messages.
      Once the Sequence Number hits the maximum value, it should be
      wrapped around to 0.  Furthermore, if the message is a
      retransmission of a previously sent message, then the Sequence
      Number value is not changed.

   o  When using IPv4 transport, the source address in the IPv4 header
      MUST be set to the local mobility anchor's IPv4 address
      (IPv4-LMAA), and the destination address in the IPv4 header MUST
      be set to the IPv4-Proxy-CoA (Care-of Address) of the mobile
      access gateway.  The Mobility Header (without the IPv6 header)
      containing the Update Notification message is encapsulated in a
      UDP header with the destination port of 5436 [RFC5844].  If IPsec
      Encapsulating Security Payload (ESP) [RFC4303] is used to protect
      signaling, the packet is processed using transport mode ESP.

   o  The format of the Update Notification message sent over IPv4 and
      protected using ESP is shown below:

         IPv4 header (src=IPv4-LMAA, dst=IPv4-Proxy-CoA)
           ESP header (in transport mode)
             UDP header (sport=5436, dport=5436)
               Mobility Header (Update Notification)
                 (one or more Mobility Header options)

   o  When using IPv6 transport, the source address in the IPv6 header
      MUST be set to the local mobility anchor's IPv6 address (LMAA).
      The destination address in the IPv6 header MUST be set to the
      Proxy-CoA of the mobile access gateway.  The Mobility Header is
      part of the IPv6 headers.

   o  The format of the Update Notification message sent over IPv6 and
      protected using ESP is shown below:

         IPv6 header (src=LMAA, dst=Proxy-CoA)
           Mobility Header (Update Notification)
           ESP header (in transport mode)
             (one or more Mobility Header options)

5.2.  Receiving the Update Notification Acknowledgement Message

   o  If the local mobility anchor does not receive an Update
      Notification Acknowledgement message from the mobile access
      gateway for the Update Notification message with the (A) flag set,
      then the local mobility anchor MUST retransmit the message.  The
      related considerations are as follows:

      *  When retransmitting an Update Notification message, the
         Sequence Number value and other message contents MUST be the
         same as in the original message.  The (D) flag in the message
         MUST be set to a value of (1).

      *  There MUST be a minimum delay of
         MIN_DELAY_BETWEEN_UPDATE_NOTIFICATION_REPLAY (Section 7), with
         a default value of 1000 milliseconds, between two retransmit
         messages.

      *  The message MUST be retransmitted up to the number of times
         defined by the configuration variable
         MAX_UPDATE_NOTIFICATION_RETRANSMIT_COUNT (Section 7), with a
         default value of (1).  If there is no Update Notification
         Acknowledgement message after the retransmission count reaches
         the value defined by the configuration variable
         MAX_UPDATE_NOTIFICATION_RETRANSMIT_COUNT, then the message MUST
         be discarded, and the event SHOULD be logged.

   o  If the local mobility anchor receives a Binding Error message with
      the Status field set to 2 as described in [RFC6275], this
      indicates that the mobile access gateway does not support the
      Update Notification message, and hence the local mobility anchor
      MUST NOT send any further Update Notification messages to that
      mobile access gateway unless an administrative action is taken.

   o  When receiving an Update Notification Acknowledgement message, the
      local mobility anchor MUST verify the Mobility Header as described
      in Section 9.2 of [RFC6275].  If the packet is dropped due to
      failure of any of the Mobility Header test checks, the local
      mobility anchor MUST follow the processing rules as described in
      Section 9.2 of [RFC6275].

   o  Upon receiving the Update Notification Acknowledgement message,
      the local mobility anchor MUST verify that the received message is
      protected by the security association that is being used to
      protect the other signaling messages between those two peers.  For
      example, if the Proxy Binding Update and Proxy Binding
      Acknowledgement messages are protected using an IPsec security
      association [RFC4301], then the Update Notification
      Acknowledgement message MUST have the IPsec protection with the
      currently established IPsec security association that is being
      used for protecting the other Proxy Mobile IPv6 signaling
      messages.

   o  If the local mobility anchor receives an Update Notification
      Acknowledgement message with a failure status and a value of 128
      or greater, then it SHOULD log an error.

   o  If the Sequence Number in the received Update Notification
      Acknowledgement message does not match any of the Update
      Notification messages that the local mobility anchor sent, then
      the message MUST be discarded, and the message should be logged.

   o  If the local mobility anchor receives an Update Notification
      Acknowledgement message from the mobile access gateway for an
      Update Notification message that did not have the (A) flag set,
      the local mobility anchor MUST process the received message in the
      same way as a response to an Update Notification message with the
      (A) flag set.

6.  MAG Considerations

6.1.  Receiving the Update Notification Message

   o  When receiving an Update Notification message, the mobile access
      gateway MUST verify the Mobility Header as described in
      Section 9.2. of [RFC6275].  If the packet is dropped due to
      failure of any of the Mobility Header test checks, the mobile
      access gateway MUST follow the processing rules as described in
      Section 9.2 of [RFC6275].

   o  Upon receiving the Update Notification message, the mobile access
      gateway MUST verify that the received packet is protected by the
      security association that is being used to protect the other
      signaling messages between those two peers.  For example, if the
      Proxy Binding Update and Proxy Binding Acknowledgement messages
      are protected using an IPsec security association, then the Update
      Notification message MUST have the IPsec protection with the
      currently established IPsec security association that is being
      used for protecting the other Proxy Mobile IPv6 signaling
      messages.

   o  If the received Update Notification message is a retransmission of
      a previously received message, as identified by the Sequence
      Number, then the mobile access gateway MUST NOT handle the message
      as a new request.  The (D) flag is used as an indication of a
      retransmitted request, e.g., due to lost messages or the local
      mobility anchor not seeing the requested update actions.  If the
      mobile access gateway has not seen the (potentially lost) initial
      request message, it MUST treat the received Update Notification
      message (with the (D) flag set) as an initial request and continue
      processing based on that.  If the mobile access gateway detects
      that the request is a retransmission based on the (D) flag and the
      Sequence Number, then it SHOULD redo the requested update action,
      e.g., when the Acknowledgement Requested ((A)) flag is not set.
      The mobile access gateway MUST always respond to the retransmitted
      request if the (A) flag is set.

   o  Upon accepting the Update Notification message, the mobile access
      gateway MUST process the message and perform the actions based on
      the Notification Reason.

      *  If the (A) flag in the message is set to a value of (1), the
         mobile access gateway MUST send an Update Notification
         Acknowledgement message with the status code field set based on
         the result of processing the Update Notification message.

      *  If the Notification Reason is set to a value of (1)
         "FORCE-REREGISTRATION", then the mobile access gateway MUST
         send a Proxy Binding Update message to the local mobility
         anchor and obtain the updated session parameters for that
         mobility session.

      *  If the Notification Reason is set to a value of (2)
         "UPDATE-SESSION-PARAMETERS", then the mobile access gateway
         MUST apply the session parameters that are obtained from the
         Update Notification message in the form of mobility options.

         However, if the mobile access gateway is unable to apply the
         received session parameters, then the mobile access gateway
         MUST apply the following considerations:

         +  If the received Update Notification message has the (A) flag
            in the message set to a value of (0), then the mobile access
            gateway MUST drop the received Update Notification message
            and log the error.

         +  If the received Update Notification message has the (A) flag
            in the message set to a value of (1), then the mobile access
            gateway MUST send an Update Notification Acknowledgement
            message with a status code value of 128
            (FAILED-TO-UPDATE-SESSION-PARAMETERS).

      *  If the Notification Reason is set to a value of (3)
         "VENDOR-SPECIFIC-REASON", then the mobile access gateway MUST
         apply the considerations related to handling of the
         Vendor-Specific Mobility option [RFC5094] that is carried in
         the Update Notification message.  However, if there is no
         Vendor-Specific Mobility option present in the message, the
         mobile access gateway MUST apply the following considerations:

         +  If the received Update Notification message has the (A) flag
            in the message set to a value of (0), then the mobile access
            gateway MUST drop the received Update Notification message
            and log the error.

         +  If the received Update Notification message has the (A) flag
            in the message set to a value of (1), then the mobile access
            gateway MUST send an Update Notification Acknowledgement
            message with a status code value of 129
            (MISSING-VENDOR-SPECIFIC-OPTION).

      *  If the Notification Reason is set to a value of (4)
         "ANI-PARAMS-REQUESTED", then the mobile access gateway MUST
         send a Proxy Binding Update message to the local mobility
         anchor with the Access Network Identifier option [RFC6757].
         The Access Network Identifier option MUST reflect the current
         access network parameters for that mobility session as known to
         the mobile access gateway at the time of sending the Proxy
         Binding Update message.

      *  For other Notification Reason values not reserved by this
         document, the processing required on the mobile access gateway
         is out of scope for this document and will be specified for
         each Notification Reason defined by other documents.

6.2.  Constructing the Update Notification Acknowledgement Message

   The mobile access gateway, when sending the Update Notification
   Acknowledgement message to the local mobility anchor, has to
   construct the message as specified below:

   o  The Sequence Number MUST be the same as the Sequence Number from
      the received Update Notification message.

   o  The Status field of the Update Notification message MUST be set to
      a value that reflects the status of the processing of the Update
      Notification request.  A value of 0 (SUCCESS) indicates that the
      handling of the Update Notification message was successful.

   o  The Update Notification Acknowledgement message MUST contain
      either the Mobile Node Identifier option or the Mobile Node Group
      Identifier option, copied from the Update Notification message.
      Furthermore, the mobile access gateway MAY include other Mobility
      Header options.

   o  The source address in the IP header of the Update Notification
      Acknowledgement message MUST be set to the destination IP address
      of the received Update Notification message.

   o  The destination address in the IP header of the Update
      Notification Acknowledgement message MUST be set to the source
      address of the received Update Notification message.

   o  If IPsec ESP is used to protect signaling, the packet is processed
      using transport mode ESP.

   o  The format of the Update Notification Acknowledgement message sent
      over IPv4 and protected using ESP is shown below:

      IPv4 header (src=IPv4-Proxy-CoA, dst=IPv4-LMAA)
        ESP header (in transport mode)
          UDP header (sport=5436, dport=5436)
            Mobility Header (Update Notification Acknowledgement)
              (one or more Mobility Header options)

   o  The format of the Update Notification Acknowledgement message sent
      over IPv6 and protected using ESP is shown below:

      IPv6 header (src=Proxy-CoA, dst=LMAA)
        Mobility Header (Update Notification Acknowledgement)
        ESP header (in transport mode)
          (one or more Mobility Header options)

7.  Protocol Configuration Variables

   This specification defines the following configuration variables that
   control the Update Notification feature.

   The mobility entities, the local mobility anchor, and the mobile
   access gateway have to allow these variables to be configured by the
   system management.  The configured values for these protocol
   variables have to survive server reboots and service restarts.

   MAX_UPDATE_NOTIFICATION_RETRANSMIT_COUNT

      This variable specifies the maximum number of times a local
      mobility anchor can retransmit an Update Notification message
      before it receives an Update Notification Acknowledgement message.
      The default value for this parameter is 1.  The suggested range of
      configured values for this variable is between 0 and 5.

   MIN_DELAY_BETWEEN_UPDATE_NOTIFICATION_REPLAY

      This variable specifies the minimum delay in seconds before an
      Update Notification message is retransmitted.  The default value
      for this parameter is 1000 milliseconds.  The suggested range of
      configured values for this variable is between 500 and
      5000 milliseconds.

8.  Security Considerations

   The Update Notification protocol described in this specification is
   for use between a local mobility anchor and a mobile access gateway.
   This specification defines two new Mobility Header messages: Update
   Notification messages and Update Notification Acknowledgement
   messages.  These Mobility Header messages are to be protected using
   the same security mechanism that is used for protecting the Proxy
   Mobile IPv6 signaling messages exchanged between a given local
   mobility anchor and mobile access gateway.

   If IPsec is used, the IPsec security association that is used for
   protecting the Proxy Binding Update and Proxy Binding Acknowledgement
   also needs to be used for protecting Update Notification and Update
   Notification Acknowledgement messages.  A Proxy Mobile IPv6
   implementation and the IPsec layer are typically able to communicate
   with each other through an implementation-specific interface, for
   example, to exchange configuration and notification information.

   The traffic selectors associated with the Security Policy Database
   (SPD) entry for protecting Proxy Binding Update and Proxy Binding
   Acknowledgement messages (Section 4.2 of [RFC5213]) have to be

   extended to include the Mobility Header Type values 19 and 20, which
   have been allocated for Update Notification and Update Notification
   Acknowledgement messages, respectively.  Furthermore, any time there
   is rekeying of the IPsec security association between the mobile
   access gateway and the local mobility anchor, the newly established
   IPsec security association will be used for protecting the Update
   Notification and Update Notification Acknowledgement messages.

9.  Acknowledgements

   The authors would like to thank Basavaraj Patil, Rajeev Koodli,
   Lionel Morand, Itsuma Tanaka, Rajesh Pazhyannur, Carlos Jesus
   Bernardos Cano, John Kaippallimalil, Brian Haberman, and other
   members of the NETEXT working group for all the comments and
   discussions on the document.

   The authors would like to thank Barry Leiba, Robert Sparks, Carlos
   Pignataro, Benoit Claise, Stephen Farrell, and Jari Arkko for their
   inputs to the document as part of the IESG review process.

10.  IANA Considerations

   IANA has taken the following actions.

   o  This specification defines a new Mobility Header Type message,
      Update Notification.  This Mobility Header message is described in
      Section 4.1.  The type value 19 for this message has been
      allocated from the "Mobility Header Types - for the MH Type field
      in the Mobility Header" registry at
      <http://www.iana.org/assignments/mobility-parameters>.

   o  This specification defines a new Mobility Header Type message,
      Update Notification Acknowledgement.  This Mobility Header message
      is described in Section 4.2.  The type value 20 for this message
      has been allocated from the "Mobility Header Types - for the MH
      Type field in the Mobility Header" registry at
      <http://www.iana.org/assignments/mobility-parameters>.

   o  This specification defines a new registry for Notification
      Reasons.  It is called the "Update Notification Reasons Registry".
      This registry has been created under the "Mobile IPv6 Parameters"
      registry at <http://www.iana.org/assignments/mobility-parameters>.
      The Notification Reason is a field in the Update Notification
      message (Section 4.1).  The number space for the Notification
      Reason field needs to be managed by IANA, under the "Update
      Notification Reason Registry".  This specification reserves the
      following type values.  The allocation policy for this field is
      "Specification Required" [RFC5226].

         +=====+===========================+====================+
         |Value|       Description         |     Reference      |
         +=====+===========================+====================+
         | 0   | Reserved                  |     [RFC7077]      |
         +=====+================================================+
         | 1   | FORCE-REREGISTRATION      |     [RFC7077]      |
         +=====+================================================+
         | 2   | UPDATE-SESSION-PARAMETERS |     [RFC7077]      |
         +=====+================================================+
         | 3   | VENDOR-SPECIFIC-REASON    |     [RFC7077]      |
         +=====+================================================+
         | 4   | ANI-PARAMS-REQUESTED      |     [RFC7077]      |
         +=====+================================================+
         |255  | Reserved                  |     [RFC7077]      |
         +=====+================================================+

   o  This specification defines a new registry for Status.  It is
      called the "Update Notification Acknowledgement Status Registry".
      This registry has been created under the "Mobile IPv6 Parameters"
      registry at <http://www.iana.org/assignments/mobility-parameters>.
      The status is a field in the Update Notification Acknowledgement
      message (Section 4.2).  The number space for the Status field
      needs to be managed by IANA, under the "Update Notification
      Acknowledgement Status Registry".  This specification reserves the
      following type values.  The allocation policy for this field is
      "Specification Required".  Status codes between 0 and 127 signify
      successful processing of the Update Notification message, and
      codes between 128 and 255 signify that an error occurred during
      processing of the Update Notification message.

         +=====+=====================================+=============+
         |Value|       Description                   |  Reference  |
         +=====+=====================================+=============+
         | 0   | SUCCESS                             |  [RFC7077]  |
         +=====+=====================================+=============+
         |128  | FAILED-TO-UPDATE-SESSION-PARAMETERS |  [RFC7077]  |
         +=====+=====================================+=============+
         |129  | MISSING-VENDOR-SPECIFIC-OPTION      |  [RFC7077]  |
         +=====+=====================================+=============+

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.

   [RFC4283]  Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
              Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
              (MIPv6)", RFC 4283, November 2005.

   [RFC5094]  Devarapalli, V., Patel, A., and K. Leung, "Mobile IPv6
              Vendor Specific Option", RFC 5094, December 2007.

   [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.

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

   [RFC6602]  Abinader, F., Gundavelli, S., Leung, K., Krishnan, S., and
              D. Premec, "Bulk Binding Update Support for Proxy Mobile
              IPv6", RFC 6602, May 2012.

11.2.  Informative References

   [PMIPv6-FLOW-MOB]
              Bernardos, CJ., Ed., "Proxy Mobile IPv6 Extensions to
              Support Flow Mobility", Work in Progress, October 2013.

   [PMIPv6-QoS]
              Liebsch, M., Seite, P., Yokota, H., Korhonen, J., and S.
              Gundavelli, "Quality of Service Option for Proxy Mobile
              IPv6", Work in Progress, November 2013.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

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

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5846]  Muhanna, A., Khalil, M., Gundavelli, S., Chowdhury, K.,
              and P. Yegani, "Binding Revocation for IPv6 Mobility", RFC
              5846, June 2010.

   [RFC5847]  Devarapalli, V., Koodli, R., Lim, H., Kant, N., Krishnan,
              S., and J. Laganier, "Heartbeat Mechanism for Proxy Mobile
              IPv6", RFC 5847, June 2010.

   [RFC6757]  Gundavelli, S., Korhonen, J., Grayson, M., Leung, K., and
              R. Pazhyannur, "Access Network Identifier (ANI) Option for
              Proxy Mobile IPv6", RFC 6757, October 2012.

   [RFC6909]  Gundavelli, S., Zhou, X., Korhonen, J., Feige, G., and R.
              Koodli, "IPv4 Traffic Offload Selector Option for Proxy
              Mobile IPv6", RFC 6909, April 2013.

Authors' Addresses

   Suresh Krishnan
   Ericsson
   8400 Blvd Decarie
   Town of Mount Royal, Quebec
   Canada

   Phone: +1 514 345 7900 x42871
   EMail: suresh.krishnan@ericsson.com

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

   EMail: sgundave@cisco.com

   Marco Liebsch
   NEC
   Kurfuersten-Anlage 36
   D-69115 Heidelberg
   Germany

   EMail: marco.liebsch@neclab.eu

   Hidetoshi Yokota
   KDDI

   EMail: yokota@kddilabs.jp

   Jouni Korhonen
   Broadcom
   Porkkalankatu 24
   Helsinki  FIN-00180
   Finland

   EMail: jouni.nospam@gmail.com

 

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