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Versions: 00 01 02 draft-ietf-mext-binding-revocation

MEXT WG                                                       A. Muhanna
Internet-Draft                                                 M. Khalil
Intended status: Standards Track                                  Nortel
Expires: January 12, 2009                                  S. Gundavelli
                                                           Cisco Systems
                                                            K. Chowdhury
                                                        Starent Networks
                                                               P. Yegani
                                                           Cisco Systems
                                                           July 11, 2008


                  Binding Revocation for IPv6 Mobility
              draft-muhanna-mext-binding-revocation-02.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on January 12, 2009.

Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document defines the revocation semantics for terminating a
   mobile node's mobility session and associated resources.  These



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   semantics are generic enough and can be used by mobility entities in
   the case of Client Mobile IPv6 and its extensions.  This mechanism
   allows the mobility entity which initiates the revocation procedure
   to request its corresponding one to terminate either one, multiple or
   all specified binding cache entries.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions & Terminology  . . . . . . . . . . . . . . . . . .  4
     2.1.  Conventions used in this document  . . . . . . . . . . . .  4
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Binding Revocation Protocol and Use Cases Overview . . . . . .  4
     3.1.  Binding Revocation Protocol  . . . . . . . . . . . . . . .  5
     3.2.  Client MIPv6 and DSMIP6 Use Case . . . . . . . . . . . . .  6
     3.3.  Multi-Care of Addresses (Monami6) Use Case . . . . . . . .  7
       3.3.1.  Termination of Multiple Care-of Addresses Bindings . .  7
       3.3.2.  Termination of All Care-of Addresses Bindings  . . . .  8
     3.4.  Proxy MIPv6 Use Case . . . . . . . . . . . . . . . . . . .  8
       3.4.1.  Local Mobility Anchor Revokes A PMIPv6 Binding . . . .  8
       3.4.2.  Local Mobility Anchor Revokes Bulk PMIPv6 Bindings . . 10
       3.4.3.  Mobile Access Gateway Revoke Bulk PMIPv6 Bindings  . . 10
   4.  Security Model . . . . . . . . . . . . . . . . . . . . . . . . 10
   5.  Binding Revocation Messages  . . . . . . . . . . . . . . . . . 10
     5.1.  Binding Revocation Indication Message  . . . . . . . . . . 10
     5.2.  Binding Revocation Acknowledgement Message . . . . . . . . 13
   6.  Binding Revocation Process Considerations  . . . . . . . . . . 15
     6.1.  Sending Binding Revocation Messages  . . . . . . . . . . . 15
     6.2.  Receiving Binding Revocation Messages  . . . . . . . . . . 15
     6.3.  Retransmission of Binding Revocation Indication  . . . . . 16
   7.  Home Agent Operation . . . . . . . . . . . . . . . . . . . . . 16
     7.1.  Sending Binding Revocation Indication  . . . . . . . . . . 16
     7.2.  Receiving Binding Revocation Acknowledgement . . . . . . . 18
   8.  Local Mobility Anchor Operation  . . . . . . . . . . . . . . . 18
     8.1.  Binding Revocation Initiator . . . . . . . . . . . . . . . 18
       8.1.1.  Sending Binding Revocation Indication  . . . . . . . . 18
       8.1.2.  Receiving Binding Revocation Acknowledgement . . . . . 20
     8.2.  Binding Revocation Responder . . . . . . . . . . . . . . . 21
       8.2.1.  Receiving Binding Revocation Indication  . . . . . . . 21
       8.2.2.  Sending Binding Revocation Acknowledgement . . . . . . 22
   9.  Mobile Access Gateway Operation  . . . . . . . . . . . . . . . 23
     9.1.  Binding Revocation Responder . . . . . . . . . . . . . . . 23
       9.1.1.  Receiving Binding Revocation Indication  . . . . . . . 23
       9.1.2.  Sending Binding Revocation Acknowledgement . . . . . . 24
     9.2.  Binding Revocation Initiator . . . . . . . . . . . . . . . 25
       9.2.1.  Sending Binding Revocation Indication  . . . . . . . . 25
       9.2.2.  Receiving Binding Revocation Acknowledgement . . . . . 26



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   10. Mobile Node Operation  . . . . . . . . . . . . . . . . . . . . 26
     10.1. Receiving Binding Revocation Indication  . . . . . . . . . 26
     10.2. Sending Binding Revocation Acknowledgement . . . . . . . . 27
   11. Protocol Configuration Variables . . . . . . . . . . . . . . . 28
   12. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 28
   13. Security Considerations  . . . . . . . . . . . . . . . . . . . 28
   14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
   15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
     15.1. Normative References . . . . . . . . . . . . . . . . . . . 29
     15.2. Informative References . . . . . . . . . . . . . . . . . . 30
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30
   Intellectual Property and Copyright Statements . . . . . . . . . . 32







































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1.  Introduction

   In the case of Mobile IPv6 and for administrative reason, sometimes
   it becomes necessary to inform the mobile node that its registration
   has been revoked and the mobile node is no longer able to receive IP
   mobility service using its Home Address.  In some networks where
   Mobile IPv4 [RFC3344] has been deployed, a similar Mobile IPv4
   registration revocation mechanism has been specified [RFC3543].

   This document defines the semantics of the revocation mechanism of a
   mobile node registration binding, which could have been established
   using a Client Mobile IPv6 or any of its extensions, e.g.  Proxy
   Mobile IPv6 signaling.  The proposed revocation mechanism uses the
   Mobile IPv6 Generic Signalling Message framework as defined in
   [ID-MGSM] which has a generic message framework which is applicable
   to Mobile IPv6 [RFC3775] and Proxy Mobile IPv6 [ID-PMIP6] and can be
   used by any two IP mobility entities.  As an example, this mechanism
   allows a local mobility agent, involved in providing IP mobility
   services to a mobile node, to notify the mobility access gateway of
   the termination of a mobile node binding registration.  In another
   example, a mobility access gateway can use this mechanism to notify
   its local mobility anchor peer with a bulk termination of all Proxy
   MIPv6 bindings that are registered with the local mobility anchor and
   currently being served by the mobility access gateway.


2.  Conventions & Terminology

2.1.  Conventions used in this document

   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 [RFC2119].

2.2.  Terminology

   All the general mobility related terminology and abbreviations are to
   be interpreted as defined in Mobile IPv6 specification [RFC3775] and
   Proxy Mobile IPv6 specification [ID-PMIP6].


3.  Binding Revocation Protocol and Use Cases Overview

   This specification defines a binding revocation mechanism using the
   framework of Mobile IPv6 Generic Signaling Message (MGSM), where a
   mobility node can communicate to the mobile node or another mobility
   node the termination of the mobile node registration binding.  The
   following subsections describe the protocol overview and applicable



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   use cases.

3.1.  Binding Revocation Protocol

   In the case of Client Mobile IPv6, the revocation procedure can be
   initiated by the home agent.  If the home network decides to
   terminate the service of the mobile node, the home agent sends a
   Binding Revocation Indication (BRI) message to the mobile node.  The
   home agent includes the HoA option as specified in [RFC3775] to
   indicate the impacted mobile node session.  When the mobile node
   receives a BRI message with its HoA included and the Acknowledge (A)
   bit is set, the mobile node responds by sending a Binding Revocation
   Acknowledgement (BRA) message.

   In the case of DSMIPv6 [ID-DSMIP6], the revocation procedure can also
   be initiated by the home agent.  If the home network decides to
   terminate the service of the mobile node, the home agent sends a BRI
   message to the mobile node to indicate the termination the mobile
   node IP Mobility service.  The home agent may include the HoA option
   with the mobile node assigned home IPv4 address.  After receiving the
   BRI message with the Acknowledge (A) bit is set, the mobile node
   responds by sending a BRA message.

   Similarly, in the case of Proxy Mobile IPv6 [ID-PMIP6], the
   revocation procedure can be initiated by the local mobility anchor by
   sending a BRI message to communicate the termination of a mobile node
   registration binding to the mobility access gateway.  In this case,
   the local mobility anchor includes the mobile node Home Network
   Prefix option [ID-PMIP6] and the MN-ID option [RFC4283] to indicate
   to the mobility access gateway the identity of the PMIPv6 binding
   that needs to be terminated.  When the mobility access gateway
   receives the BRI message with the (A) bit set, the mobility access
   gateway responds to the local mobility anchor by sending a BRA
   message.

   On the other hand, the mobility access gateway usually sends a de-
   registration message by sending a Proxy BU with a lifetime of zero to
   indicate to the local mobility anchor of the termination of the
   PMIPv6 mobile node binding registration.  In this case, the mobility
   access gateway include the MN home network prefix option and the
   MN-ID option as per [ID-PMIP6] in order for the local mobility anchor
   to identify the mobile node PMIPv6 binding.  However, in the case
   when the mobility access gateway communicates a bulk termination of
   PMIPv6 sessions, the mobility access gateway sends a BRI message with
   the G bit set and includes the mobility access gateway identity in
   the MN-ID option.  When the local mobility anchor receives such BRI
   message, it ensures that the mobility access gateway is authorized to
   send such bulk termination message and then process the BRI message



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   accordingly.  If the local mobility anchor processes the BRI message
   successfully and the (A) bit is set in the BRI, the local mobility
   anchor responds to the mobile access gateway by sending a BRA
   message.  Additionally, the initiator of the binding revocation
   procedure include an indication in the Revocation Trigger field to
   indicate to the receiving node the cause for the revocation
   procedure.

3.2.  Client MIPv6 and DSMIP6 Use Case

   Binding revocation mechanism is applicable to Client Mobile IPv6 and
   DSMIPv6 session when the home agent needs to inform the mobile node
   that its binding registration has been revoked, e.g. for an
   administrative reason.  This mechanism enables the home domain to
   dynamically allow the user to act upon the revocation message in
   order to not have an unexpectedly interrupted mobile IPv6 services.


   In this case, the home agent sends a BRI message to indicate to the
   mobile node that its current mobile IPv6 binding has been revoked and
   it no longer can receive IP mobility service.  The home agent
   includes the mobile node home address in HoA option, in the
   destination option header as used in [RFC3775] and sets the
   Revocation Trigger field to a proper value, e.g.  Administrative.  In
   the case of DSMIPv6 session, the home agent may additionally include
   the mobile node assigned IPv4 Home Address Option .  When the mobile
   node receives the BRI message, it sends a BRA message as described in
   Section 10.2 to the home agent.  Figure 1 illustrates the message
   sequencing when home agent revokes a mobile node binding
   registration.



         MN                                         HA
         |                                           |
         | HoA in Dest. Opt. Hdr + BRI[seq.#, A bit] |
         |<------------------------------------------|
         |                                           |
         |                                           |
         |                                           |
         |                BRA[seq.#]                 |
         |------------------------------------------>|
         |                                           |
         |                                           |



      Figure 1: Home Agent Revokes a Mobile Node Binding Registration



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3.3.  Multi-Care of Addresses (Monami6) Use Case

   In the case of Monami6 protocol, a mobile node is able to register
   multiple care-of addresses for the same home address [ID-MCoA].
   Binding revocation mechanism is applicable to Monami6 when the home
   agent sends a BRI message to revoke a single or more care-of address
   bindings.

3.3.1.  Termination of Multiple Care-of Addresses Bindings

   In the case of multiple care-of addresses, the home agent maintains
   different binding for each pair of care-of address and home address.
   These bindings are also indexed and identified during the mobile node
   registration using a new Binding ID mobility option [ID-MCoA].  In
   this case, the home agent may revoke any binding, more than one
   binding, or all of the bindings for the same mobile node home
   address.

   In the case when home agent revokes a single binding for a mobile
   node with multiple care-of addresses registration, the home agent
   send a BRI message to the mobile node with the corresponding BID
   option included and the HoA option in the destination option header.
   If the home agent needs to revoke more than one of the mobile node
   registered care-of addresses, the home agent includes all the
   corresponding BID options which reference these care-of addresses in
   the same BRI message.  Figure 2 illustrates the message flow when the
   home agent revokes two registered Care-of addresses for the same MN
   in a single BRI message.  The home agent can revoke any registered
   bindings by sending a BRI message to the respective mobile node.


                                                      HA Binding Cache
                                                      ================
                                                      MN-BID1 [CoA1+HoA]
      MN                                        HA    MN-BID2 [CoA2+HoA]
      |                                           |   MN-BID3 [CoA3+HoA]
      |   BRI [seq.#, A bit, BID1, BID4 options]  |   MN-BID4 [CoA4+HoA]
      |<------------------------------------------|
      |                                           |
      |                                           |
      |                                           |
      |             BRA [seq.#, Cause]            |
      |------------------------------------------>|
      |                                           |
      |                                           |






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   Figure 2: Home Agent Revokes MN's Specific Care-of Addresses Bindings


3.3.2.  Termination of All Care-of Addresses Bindings

   The home agent may revoke all of the mobile node registered bindings,
   by sending a BRI message without including any BID options while the
   HoA option is included in the destination options header.  Figure 1
   illustrates the message flow when the home agent revokes all
   registered Care-of addresses bindings for a MN in a single BRI
   message.


3.4.  Proxy MIPv6 Use Case

   Since the Mobile node does not participate in the mobility mechanism
   in the case of PMIPv6, there are many scenarios where Binding
   Revocation mechanism is needed to clean resources and make sure that
   the mobility entities, e.g.  MAG and LMA, are always synchronized
   with the status of the existing proxy mobile IPv6 bindings.  The
   binding revocation mechanism is generic enough that can be used in
   all applicable PMIPv6 scenarios and deployment options.  For example,
   this revocation mechanism is still applicable and can be used when
   PMIPv6 is deployed with IPv6 or IPv4 transports and when the mobile
   node uses IPv4 or IPv6 address as specified in [ID-PMIP6-IPv4].


   When the mobile access gateway receives a BRI message as in
   Section 9.1.1, the mobile access gateway sends a BRA message to the
   local mobility anchor following the rules describes in Section 9.1.2.
   Similarly if the local mobility anchor receives a BRI message with
   the A bit is set, the local mobility anchor responds to the mobile
   access gateway by sending a BRA message.


3.4.1.  Local Mobility Anchor Revokes A PMIPv6 Binding

   The local mobility anchor may send a BRI message to the mobile access
   gateway, hosting a specific proxy mobile IPv6 session, with the
   appropriate value in the revocation trigger field to indicate that
   the mobile node binding has been terminated and the mobile access
   gateway can clean up the applicable resources.  When the mobile
   access gateway receives a BRI message, the MAG identify the respected
   binding and if the A bit was set in the received BRI message, the MAG
   sends a BRA message to the LMA.  In this case, the MAG could send a
   Router Advertisement message to the MN with the home network prefix
   lifetime is set to zero.




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   As an example, Figure 3, illustrates the message sequence for
   revoking a mobile node binding at the source MAG during the MN inter-
   MAG handoff.  During the inter-MAG handoff, the mobile node moves
   from the source MAG to the target MAG.  The target MAG sends a PBU
   with the new care-of-address to the LMA to update the mobile node
   point of attachment.  Since the MN binding at the LMA points to the
   source MAG and upon receiving the PBU from the target MAG, LMA
   updates the MN BCE and send a PBA to the target MAG.  LMA can send a
   BRI message with the appropriate revocation trigger value, e.g.
   inter-MAG handoff indication, to the source MAG in order to clean up
   the applicable resources reserved for the specified MN.  The MAG
   acknowledges the BRI message by sending a BRA message to indicate the
   success or failure of the termination of the mobile node binding.

   The process identified above can also be used by the LMA in scenarios
   other than the inter-MAG handoff with the proper revocation trigger
   value to indicate to the peer MAG that a specific proxy mobile IPv6
   binding or bindings have been revoked.


               sMAG         tMAG                          LMA
               |             |                            |
               |             |        PBU                 |
               |             |--------------------------->|
               |             |                      PBU triggers
               |             |                     BRI Msg to sMAG
               |             |                            |
               |             |        PBA                 |
               |             |<---------------------------|
               |             |                            |
               |             |                            |
               | BRI [seq.#, R. Trigger, P, A bits, NAI]  |
               |<-----------------------------------------|
               |             |                            |
               |             |                            |
               |             |                            |
               |             |                            |
               |        BRA [seq.#, Cause, P bit]         |
               |----------------------------------------->|
               |             |                            |
               |             |                            |



     Figure 3: LMA Revokes a MN Registration During Inter-MAG Handoff






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3.4.2.  Local Mobility Anchor Revokes Bulk PMIPv6 Bindings

   The local mobility anchor sends a BRI message to indicate that all
   bindings which are hosted by the peer mobile access gateway and
   registered with the local mobility anchor are being revoked by
   setting the G bit as described in Section 8.1.1.


3.4.3.  Mobile Access Gateway Revoke Bulk PMIPv6 Bindings

   The mobile access gateway sends a BRI message with the G bit is set
   to indicate that all mobility sessions which are registered at the
   LMA and attached to the MAG are being revoked as in Section 9.2.1.
   When the LMA receives a BRI message with the G bit is set from a
   specified MAG, the LMA checks if the MAG is authorized to use global
   revocations and responds with the appropriate status code by sending
   a BRA message as in Section 8.2.2.


4.  Security Model

   The revocation protocol described here requires the revocation
   messages to be defined as subtypes of the Mobile IPv6 Generic
   Signalling Message which is assigned a MH type value <IANA-TBD>
   [ID-MGSM] that requires IPsec protection.  This is needed in order
   when IPsec is used for securing the mobility signalling between ,
   e.g., the MAG and the LMA, the IPsec SPD will allow all MGSM packets
   including those which carry binding revocation messages.

   Additionally, in the case when the LMA receives a BRI which indicates
   a bulk termination, the LMA MUST verify that the MAG sending the
   revocation indication message is authorized for Per-Peer Global
   revocation.


5.  Binding Revocation Messages

   This section defines two messages by reserving two subtypes of the
   Mobile IPv6 Generic Signalling Message that use the MH type which
   requires IPsec protection as defined in [ID-MGSM].


5.1.  Binding Revocation Indication Message

   The Binding Revocation Indication (BRI) message is used by the
   revoking mobility node to inform the receiving mobility entity that
   the IP mobility service of a specific binding or bindings have been
   revoked.  Binding Revocation Indication message is sent as described



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   in Section 7.1, Section 8.1.1, and Section 9.2.1.

   The Binding Revocation Indication (BRI) message uses the subtype
   <IANA-SUB1> of the MGSM message that use the MH type which requires
   IPsec protection as in [ID-MGSM].  When this subtype is indicated in
   the subtype field of the MGSM, the format of the Message Data field
   in the MGSM message following the subtype field is as in Figure 4


       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 #           |  R. Trigger   |P|A|G|Reserved |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       .                                                               .
       .                        Mobility options                       .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



              Figure 4: Binding Revocation Indication Message


   Sequence #

      A 16-bit unsigned integer used by the sending mobility node to
      match a returned Binding Revocation Acknowledgement with this
      Binding Revocation Indication.

   Revocation Trigger

      8-bit unsigned integer indicting the event which triggered the
      revoking node to send the BRI message.  The following Revocation
      Trigger values are currently defined:

          0  Reserved.
          1  Unspecified.
          2  Administrative Reason.
          3  Inter-MAG Handover over same Access Types.
          4  Inter-MAG Handover over different Access Types.
          5  Per-Peer Policy.
          6  Local Policy.







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   Proxy Binding (P)

      The Proxy Binding (P) bit is set by the sending mobility node to
      indicate that the revoked binding is a proxy MIPv6 binding.

   Acknowledge (A)

      The Acknowledge (A) bit is set by the sending mobility node, e.g.
      LMA, HA, or MAG, to request a Binding Revocation Acknowledgement
      be returned upon receipt of the Binding Revocation Indication as
      in Section 7.1, Section 8.1.1, and Section 9.2.1.

   Global (G)

      The Global (G) bit is set by the sending mobility node, LMA or
      MAG, to request the termination of all Per-Peer mobility Bindings
      that are served by the sending and receiving mobility entities as
      in Section 8.1.1 and Section 9.2.1.

   Reserved

      These fields are unused.  They MUST be initialized to zero by the
      sender and MUST be ignored by the receiver.

   Mobility Options

      Variable-length field of such length that the complete Mobility
      Header is an integer multiple of 8 octets long.  This field
      contains zero or more TLV-encoded mobility options.  This document
      does not define any new mobility option.  The receiver MUST ignore
      and skip any options which it does not understand.  These mobility
      option(s) are used by the receiving mobility entity to identify
      the specific binding or bindings that the sending mobility entity
      requesting to be revoked.

   The following options are valid in a Binding Revocation Indication:

   o  Home Network Prefix option [ID-PMIP6].  This option is mandatory
      when the P bit is set.

   o  Mobile Node Identifier Option [RFC4283].  This option is mandatory
      when the P bit is set.  Additionally, If the G bit is set by the
      mobile access gateway, this option include the MAG identity.

   o  Binding ID mobility option [ID-MCoA].  This option is mandatory if
      the sending mobility entity request to terminate one binding of a
      multi care-of addresses bindings for the same mobile node.  The
      sending Mobility entity may include more than one of these



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      mobility options.

   o  IPv4 Home Address option which contains the mobile node home IPv4
      address [ID-DSMIP6].

   If no options are present in this message, 4 octets of padding are
   necessary and the Header Len field of the MGSM will be set to 1.

5.2.  Binding Revocation Acknowledgement Message

   The Binding Revocation Acknowledgement is used to acknowledge receipt
   of a Binding Revocation Indication described in Section 5.1.  This
   packet is sent as described in Section 8.2.2, Section 9.1.2, and
   Section 10.2.

   The Binding Revocation Acknowledgement uses the subtype <IANA-SUB2>
   of the MGSM message that use the MH type which requires IPsec
   protection as in [ID-MGSM].  When this subtype is indicated in the
   subtype field of the MGSM, the format of the Message Data field in
   the MGSM message following the subtype field is as in Figure 5:



       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    |P|G|  Reserved |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       .                                                               .
       .                        Mobility options                       .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



           Figure 5: Binding Revocation Acknowledgement Message


   Sequence #

      The sequence number in the Binding Revocation Acknowledgement is
      copied from the Sequence Number field in the Binding Revocation
      Indication.  It is used by the revoking mobility entity, e.g.  HA,
      LMA, in matching this Binding Revocation Acknowledgement with the
      outstanding BRI.




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   Status

      8-bit unsigned integer indicating the result of processing the
      Binding Revocation Indication message by the receiving mobility
      entity.  The following status values are currently defined.

          0  success.
          1  partial success.
          2  Binding Does NOT Exist.
          3  Global Revocation NOT Authorized.
          4  CAN NOT Identify Binding.

   Proxy Binding (P)

      The Proxy Binding (P) bit is set if the (P) bit is set in the
      corresponding Binding Revocation Indication message.

   Global (G)

      The Global (G) bit is set if the (G) bit is set in the
      corresponding BRI message.  Section 8.2.2 and Section 9.1.2.

   Reserved

      These fields are unused.  They MUST be initialized to zero by the
      sender and MUST be ignored by the receiver.

   Mobility Options

      Variable-length field of such length that the complete Mobility
      Header is an integer multiple of 8 octets long.  This field
      contains zero or more TLV-encoded mobility options.  In the case
      when the Status field is set to success, no mobility option is
      required.  The mobility option(s) is usually used to communicate
      information of the bindings that failed the revocation procedure.

   The following options are valid in a Binding Revocation
   Acknowledgement:

   o  Home Network Prefix option [ID-PMIP6].  This option is mandatory
      when the P bit is set.

   o  Mobile Node Identifier Option [RFC4283].  This option SHOULD be
      included if the Home Network Prefix option is included.

   o  Binding ID mobility option [ID-MCoA].  This option MAY be included
      to indicate the specific Binding ID that the receiving node failed
      to revoke.



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   If no options are present in this message, 4 octets of padding are
   necessary and the Header Len field of the MGSM will be set to 1.


6.  Binding Revocation Process Considerations

   The following subsections describe the details of the binding
   revocation generic process by the different mobility entities.

6.1.  Sending Binding Revocation Messages

   When sending a Binding Revocation message, the sending mobility node,
   initiator, follows the rules of constructing a MGSM as in [ID-MGSM]
   and by setting the subtype field to a value <IANA-SUB1> to indicate a
   BRI message.

   The mobility entity which initiates the revocation process,
   initiator, MUST use the underlying IPsec security association as
   described in [ID-MGSM] to secure the BRI and BRA messages
   transmission with the responding mobility entity, responder.

   When a mobility entity initiate the binding revocation process by
   sending a Binding Revocation Indication, the initiator MUST construct
   the BRI message as described in Section 5.1.  In the BRI message, the
   initiator MUST set the Sequence Number field to the next sequence
   number available for Binding Revocation.  Since sending Binding
   Revocation Indication messages is not done on a regular basis, a 16
   bit sequence number field is large enough to allow the initiator to
   match the Binding Revocation Acknowledgement to the outstanding
   Binding Revocation Indication with (A) bit set using the sequence
   number field only.

   On the other hand, when the responder acknowledge the BRI message by
   sending a BRA, the responder follows the rules of constructing a MGSM
   as in [ID-MGSM] and by setting the subtype field to a value <IANA-
   SUB12> to indicate a BRA message and MUST construct the Binding
   Revocation Acknowledgement as described in Section 5.2.  In this
   case, the responder MUST set the Sequence Number field by copying the
   value from the Sequence Number field of the received Binding
   Revocation Indication.  Additionally, it MUST set the status field to
   a valid value that reflects the processing of the received Binding
   Revocation Indication.

6.2.  Receiving Binding Revocation Messages

   When receiving a Binding Revocation message, the receiving mobility
   node MUST verify the Mobile IPv6 Generic Signaling Message as in
   [ID-MGSM].  If the packet is dropped due to the receiving node does



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   not support Binding Revocation Indication as a MGSM with subtype
   <IANA-SUB1>, it MUST follow the processing rules as in [ID-MGSM] and
   it MUST send a Binding Error message with the Status field set to 2
   (unrecognized MH Type value).

   Since some mobility entities, e.g.  LMA and MAG, are allowed to
   receive and possibly send a BRI or a BRA for different cases, IPsec
   mechanism will prevent any possible man in the middle reflection
   attack.

   Upon receiving a packet carrying a Binding Revocation Indication, the
   receiving mobility entity, responder, validates that the packet was
   received protected with the underlying IPsec protection with the
   responding mobility entity as described in [ID-MGSM].

   Upon receiving a packet carrying a Binding Revocation
   Acknowledgement, the receiving mobility entity, initiator, MUST
   validate that Sequence Number field matches the Sequence Number of an
   outstanding Binding Revocation Indication that was sent by the
   initiator.  If the Sequence Number does not match any sequence number
   of any of the outstanding BRI, the receiving node MUST ignore the
   message but MAY log the event.

6.3.  Retransmission of Binding Revocation Indication

   If the sending mobility entity does not receive a Binding Revocation
   Acknowledgement in response to the outstanding Binding Revocation
   Indication before the MINDelayBRIs timer expires, the mobility
   entity, e.g.  LMA, may retransmit the same BRI message up to the
   BRIMaxRetriesNumber as defined in Section 11.  If the revoking
   mobility entity does not receive a BRA message after the maximum
   number of retransmits have been sent, the revoking mobility entity
   can clean the mobile node binding cache and all resources associated
   with this binding.  The revoking mobility entity may log the event.


7.  Home Agent Operation

7.1.  Sending Binding Revocation Indication

   When an event requires the home agent to terminate a mobile node
   mobile IPv6 registration, e.g. for administrative reason, the home
   agent sends a Binding Revocation Indication message to the mobile
   node to inform the mobile node that its specified binding has been
   revoked and it will no longer be able to receive an IP connectivity
   via its binding with the home agent.

   To terminate a mobile node registration and its current binding with



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   the home agent, the home agent sends a packet to the mobile node
   containing a Binding Revocation Indication, with the packet
   constructed as follows:

   o  The Acknowledge (A) bit MAY be set in the Binding Revocation
      Indication to request the mobile node to send a Binding Revocation
      Acknowledgement upon receipt of the BRI.

   o  The Revocation Trigger field MUST be set in the Binding Revocation
      Indication to indicate to the mobile node the reason for revoking
      its IP mobility binding with the home agent.  The Revocation
      Trigger may be used by the mobile node to take further steps if
      necessary.

   o  The packet MUST contain a Home Address destination option, which
      contains the mobile node's registered home address for the binding
      being revoked.

   o  The care-of address for the binding MUST be used as the Source
      Address in the packet's IPv6 header, unless an Alternate Care-of
      Address mobility option is included in the Binding Revocation
      Indication.

   o  The packet MAY contain a Home Address option which contains the
      mobile node's registered IPv4 home address for the binding being
      revoked.


   The Acknowledge (A) bit in the Binding Revocation Indication requests
   the mobile node to return a Binding Revocation Acknowledgement in
   response to this Binding Revocation Indication.  As described in
   Section 6.3, the home agent SHOULD retransmit this Binding Revocation
   Indication to the mobile node before terminating its IP connection
   until it receives a matching Binding Revocation Acknowledgement or
   the BRIMaxRetransmitNumber has been reached.

   When the home agent send a Binding Revocation Indication to the
   mobile node, the home agent sets a flag in the mobile node BCE to
   indicate that revocation is in progress and starts the MINDelayBRIs
   timer.  The home agent maintain the mobile node BCE in this state
   until it receives a Binding Revocation Acknowledgement or the
   BRIMaxRetransmitNumber is reached.

   When the home agent needs to revoke one or more of a mobile node
   bindings that were created using Multi Care-of address registration
   as in [ID-MCoA], the home agent MUST include all the related Binding
   ID options that identify these bindings.  In the case when the home
   agent needs to revoke all of the mobile node bindings, the home agent



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   MUST use the mobile node home address in the Home Address destination
   option and MUST NOT include any Binding ID option.

   The home agent MUST use the IPsec security association as described
   in [ID-MGSM] to secure the MGSM that carries the BRI and BRA messages
   transmission with the mobile node.

7.2.  Receiving Binding Revocation Acknowledgement

   When the home agent receives a packet carrying a valid Binding
   Revocation Acknowledgement that was successfully processed as in
   Section 6.2, the home SHOULD examine the Status field as follows:

   o  If the Status field indicates that the Binding Revocation
      Indication was processed successfully, the home agent delete the
      MINDelayBRIs timer and the mobile node bindings and all related
      resources.

   o  If the Status field indicates any value other than success, the
      home agent SHOULD examine any mobility options included in the
      Binding Revocation Acknowledgement.  The home agent MAY log the
      appropriate event to reflect the status of the received BRA.



8.  Local Mobility Anchor Operation

8.1.  Binding Revocation Initiator

8.1.1.  Sending Binding Revocation Indication

   When an event requires the local mobility agent to terminate a mobile
   node proxy mobile IPv6 registration, e.g. for administrative reason
   or inter-MAG handover, the local mobility agent sends a Binding
   Revocation Indication message to the mobile access gateway which host
   the mobile node proxy CoA to indicate that the mobile node specified
   binding should be removed.  It also indicate that the local mobility
   anchor will no longer maintain a tunnel for this mobile node binding
   which points to the mobile node proxy CoA that is hosted at this
   mobile access gateway.

   To terminate a mobile node proxy mobile IPv6 registration and its
   current PMIPv6 binding with the local mobility agent, the local
   mobility agent sends a packet to the mobile access gateway containing
   a Binding Revocation Indication following the procedure in
   Section 6.1 and the following rules:





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   o  The Acknowledge (A) bit MAY be set in the Binding Revocation
      Indication to request the mobile access gateway to send a Binding
      Revocation Acknowledgement upon receipt of the BRI.

   o  The Proxy Mobile IP (P) bit MUST be set in the Binding Revocation
      Indication to indicate that the binding being revoked is a proxy
      Mobile IPv6 binding.

   o  The Revocation Trigger field MUST be set in the Binding Revocation
      Indication to indicate to the mobile access gateway the reason for
      removing the specified mobile node proxy mobile IPv6 binding at
      the local mobility anchor.  The Revocation Trigger may be used by
      the mobile access gateway node to learn the mobile node latest
      movement.

   o  The Global (G) bit MUST be set and the Revocation Trigger MUST
      contain a value of Per-Peer Policy in the Binding Revocation
      Indication to request the mobile access gateway to remove all Per-
      Peer bindings that are registered with the local mobility anchor
      and hosted at this mobile access gateway.

   o  The packet MUST contain the Mobile Node Identifier, MN-ID, option
      which contains the mobile node's NAI that was used in the Binding
      Update during the mobile node registration.

   o  The packet MUST contain a Home Network Prefix option, which
      contains the mobile node's registered Home Network Prefix for the
      binding being revoked.

   o  The care-of address for the binding MAY be used as the Source
      Address in the packet's IPv6 header, unless an Alternate Care-of
      Address mobility option is included in the Binding Revocation
      Indication.


   The Acknowledge (A) bit in the Binding Revocation Indication requests
   the mobile access gateway to return a Binding Revocation
   Acknowledgement in response to this Binding Revocation Indication.
   As described in Section 6.3, the local mobility anchor SHOULD
   retransmit this Binding Revocation Indication to the mobile access
   gateway before deleting the mobile node IP tunnel to the mobile
   access gateway until it receives a matching Binding Revocation
   Acknowledgement or the BRIMaxRetransmitNumber is reached.  If the A
   bit is not set in the Binding Revocation Indication, the local
   mobility anchor MAY delete the mobile node IP tunnel immediately
   after sending the Binding Revocation Indication.

   When the local mobility anchor send a Binding Revocation Indication



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   to the mobile access gateway to remove a specific binding, the local
   mobility anchor sets a flag in the mobile node proxy BCE to indicate
   that revocation is in progress and starts the MINDelayBRIs timer.
   The local mobility anchor SHOULD maintain the mobile node proxy BCE
   in this state until it receives a Binding Revocation Acknowledgement
   or the BRIMaxRetransmitNumber is reached.  In the case when the local
   mobility anchor sets the Revocation Trigger field to a value which
   indicate inter-MAG handover, the local mobility anchor MAY switch the
   mobile node IP tunnel to the target mobile access gateway before
   sending a Binding Revocation Indication to the sources mobile access
   gateway.

   When the local mobility anchor needs to revoke all mobile nodes proxy
   BCE that are registered with the local mobility anchor and hosted at
   the mobile access gateway, the local mobility anchor MUST set the
   Global (G) bit and the value of the Revocation Trigger field to Per-
   Peer Policy.  In this case, the local mobility anchor MUST NOT
   include any mobility options in the Binding Revocation Indication.

   When the local mobility anchor needs to revoke all mobile nodes proxy
   BCE that belong to a specific realm, e.g. @companyabc.com, and are
   registered with the local mobility anchor and hosted at the mobile
   access gateway, the local mobility anchor MUST set the Global (G) bit
   and the value of the Revocation Trigger field to Local Policy.  In
   this case, the local mobility anchor MUST include a mobility option
   to identify the impacted bindings, e.g.  MN-ID option with a wildcard
   NAI, e.g. *@companyabc.com, to identify all the mobile nodes BCEs
   that need to be removed.

   When the mobile node is registered with multiple Home Network
   Prefixes for the same proxy care-of address, the local mobility
   anchor SHOULD include a Home Network Prefix option for each
   registered Home Network Prefix in the Binding Revocation Indication.
   Alternatively, the local mobility anchor MAY include only the mobile
   node identifier, MN-ID, option in the Binding Revocation Indication
   to indicate to the mobile access gateway to remove all bindings of
   the specified mobile node NAI in the MN-ID option.

8.1.2.  Receiving Binding Revocation Acknowledgement

   When the local mobility anchor receives a packet carrying a valid
   Binding Revocation Acknowledgement that was successfully processed as
   in Section 6.2 and if the mobile node BCE is in the state of
   Revocation in progress, the local mobility anchor SHOULD examine the
   Status field before clearing the mobile node related resources as
   follows:





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   o  If the Status field indicates that the Binding Revocation
      Indication was processed successfully, the local mobility anchor
      delete the MINDelayBRIs timer and the mobile node proxy bindings
      and all associated resources.

   o  If the Status field indicates partial success value or MN binding
      does not exist, the local mobility anchor SHOULD examine mobility
      options that included in the Binding Revocation Acknowledgement,
      if any, before deleting the MINDelayBRIs timer and the mobile node
      associated proxy bindings and all related resources.  It is based
      on the local mobility anchor local policy how to handle the Mobile
      node BCE that the mobile access gateway indicated it failed the
      revocation procedure, however, the LMA MAY log the event.


8.2.  Binding Revocation Responder

8.2.1.  Receiving Binding Revocation Indication

   When the local mobility anchor receives a packet carrying a Binding
   Revocation Indication that was successfully processed as in
   Section 6.2, the local mobility anchor SHOULD in addition process the
   message as follows:

   o  Binding Revocation Indication is formatted as in Section 5.1 and
      if the (P) bit is set, the local mobility anchor must validate
      that all the impacted bindings MUST have the proxy binding flag
      set.

   o  If the Global (G) bit is set, the Binding Revocation Indication
      SHOULD contain the mobile access gateway ID in the MN-ID option.
      The local mobility anchor MUST verify that the identified mobile
      access gateway as per the value in the MN-ID option is authorized
      to use the Per-Peer Global bindings revocation.  The mechanism the
      local mobility anchor use to verify the mobile access gateway
      authorization is out of scope of this document.  When the (P) bit
      is set, this Binding Revocation Indication impact only the mobile
      nodes bindings that have the Proxy Mobile IP flag set.

   o  The local mobility anchor identify all impacted mobile nodes
      bindings and if the Acknowledgement (A) bit is set, the local
      mobility anchor MUST send a Binding Revocation Acknowledgement
      following Section 8.2.2 using the appropriate status code.

   o  If the Global (G) bit is not set, the local mobility anchor MUST
      use the included mobility options to identify the impacted mobile
      node binding as follows:




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      1.  If only the mobile node identifier, MN-ID, option is included,
          the local mobility anchor MUST revoke all bindings for this
          mobile node which have a proxy CoA that is hosted at the
          mobile access gateway that sent the BRI.

      2.  If the mobile node identifier, MN-ID, and the Home Network
          Prefix option are included, the local mobility anchor MUST
          only remove the specified proxy binding.

      3.  If the mobile node identifier, MN-ID, option and more than one
          Home Network Prefix options are included, the local mobility
          anchor need to remove the mobile node bindings which are
          referenced in these multiple Home Network Prefixes for the
          specified mobile node NAI.


   The Revocation Trigger field value in the received Binding Revocation
   Indication could be used by the local mobility anchor to log an event
   or update some local parameters which tracks the state of the peer
   mobile access gateway.

8.2.2.  Sending Binding Revocation Acknowledgement

   When the local mobility anchor receive a valid Binding Revocation
   Indication with the (A) bit is set and after processing the BRI
   message, the local mobility anchor sends a packet to the mobile
   access gateway containing a Binding Revocation Acknowledgement
   following the process in Section 6.1 and the following:

   o  If the (P) bit was set in the received Binding Revocation
      Indication, the local mobility anchor MUST set the (P) bit in the
      Binding Revocation Acknowledgement.

   o  If the Global (G) bit was set in the received BRI, the local
      mobility anchor MUST set the (G) bit in the Binding Revocation
      Acknowledgement.

   o  The local mobility anchor MUST set the status field to a valid
      code that reflects the processing of the received Binding
      Revocation Indication.  If the mobile access gateway is not
      authorized to use the Per-Peer Global revocation feature, the LMA
      MUST set the status field to (Global Revocation NOT Authorized).

   o  The local mobility MAY set the status field to partial success and
      in this case it MAY include the mobile node identifier or the Home
      Network Prefix option to identify the bindings that failed
      revocation.




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   o  The destination IP address of the IPv6 packet of the Binding
      Revocation Acknowledgement is set to the source IP address of the
      received Binding Revocation Indication.



9.  Mobile Access Gateway Operation

9.1.  Binding Revocation Responder

9.1.1.  Receiving Binding Revocation Indication

   Upon receiving a packet carrying a Binding Revocation Indication, the
   mobile access gateway MUST validate the packet according to
   Section 6.2 and the following:

   o  Binding Revocation Indication MUST be formatted as in Section 5.1
      and if the (P) bit is set, the mobile access gateway must validate
      that the impacted binding have the proxy binding flag set.

   o  If the Acknowledgement (A) bit in the received BRI is set, the
      mobile access gateway MUST send a Binding Revocation
      Acknowledgement following Section 9.1.2 using the appropriate
      status value.

   o  If the Global (G) bit is set and the Revocation Trigger field is
      set to Per-Peer policy, the mobile access gateway identify all
      bindings that are registered at the local mobility anchor and
      hosted at the mobile access gateway.  This Binding Revocation
      Indication does not include any other mobility options.  However,
      if the (P) bit is set, this Binding Revocation Indication MUST
      only impact mobile nodes bindings that have the Proxy Mobile IP
      flag set.

   o  If the Global (G) bit is set and the Revocation Trigger field is
      set to Local policy, the mobile access gateway MUST identify all
      bindings that are registered at the local mobility anchor and
      hosted at the mobile access gateway using the mobility option
      included in the Binding Revocation Indication.  This Binding
      Revocation SHOULD include at least the MN-ID option, e.g. with a
      wild card NAI.

   o  If the Global (G) bit is set and the Revocation Trigger field is
      set to Local policy, and no mobility options are included in the
      Binding Revocation Indication message, the mobile access gateway
      MUST treat this as an error scenario.  In this case, the mobile
      access gateway SHOULD send a Binding Revocation Acknowledgement
      message with status "CAN NOT Identify Binding".



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   The Revocation Trigger field value in the received Binding Revocation
   Indication could be used by the mobile access gateway to define what
   actions the mobile access gateway could do to inform the mobile node
   that its IP connectivity to the current Home Network Prefix has been
   terminated. e.g. if the Revocation Trigger field is set to
   administrative value, the mobile access gateway may send a RA message
   after setting the Home Network Prefix lifetime to zero.

   If the Revocation Trigger field value in the received Binding
   Revocation Indication message indicate an inter-MAG handover and the
   (A) bit is set, the mobile access gateway MAY validate that the
   mobile node is no longer attached to the mobile access gateway before
   sending a Binding Revocation Acknowledgement message to the local
   mobility anchor.

9.1.2.  Sending Binding Revocation Acknowledgement

   When the mobile access gateway receive a valid Binding Revocation
   Indication with the (A) bit is set and after processing the BRI
   message, the mobile access gateway sends a packet to the local
   mobility anchor containing a Binding Revocation Acknowledgement
   according to the procedure in Section 6.1 and the following:

   o  The mobile access gateway MUST set the (P) bit in the Binding
      Revocation Acknowledgement if it is set in the received BRI.

   o  If the Global (G) bit was set in the received BRI, the mobile
      access gateway MUST set the (G) bit in the Binding Revocation
      Acknowledgement.

   o  The mobile access gateway MUST set the status field to a valid
      code that reflects the processing of the received Binding
      Revocation Indication.

   o  The mobile access gateway MAY set the status field to partial
      success and in this case it MAY include the mobile node
      identifier, MN-ID, or the Home Network Prefix option to identify
      the binding(s) that failed to be removed as part of the revocation
      procedure.

   o  The destination IP address of the IPv6 packet of the Binding
      Revocation Acknowledgement is set to the source IP address of the
      received Binding Revocation Indication.








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9.2.  Binding Revocation Initiator

9.2.1.  Sending Binding Revocation Indication

   The mobile access gateway send a Binding Revocation Indication when
   it needs to use global revocation, i.e. when the G bit is set.  In
   this case when an event occurs which requires the mobile access
   gateway to inform the local mobility anchor to terminate all mobile
   nodes bindings that are registered at the local mobility anchor and
   the mobile access gateway, the mobile access gateway send a Binding
   Revocation Indication message following Section 6.1 and the
   following:

   o  The Acknowledge (A) bit MAY be set in the Binding Revocation
      Indication to request the local mobility anchor to send a Binding
      Revocation Acknowledgement upon receipt of the BRI.

   o  The Proxy Mobile IP (P) bit MUST be set in the Binding Revocation
      Indication to indicate that bindings that being revoked is a proxy
      Mobile IPv6 binding.

   o  The Global (G) bit MUST be set and the Revocation Trigger MUST
      contain a value of Per-Peer Policy in the Binding Revocation
      Indication to request the local mobility anchor to remove all Per-
      Peer bindings that are registered with the local mobility anchor
      and hosted at this mobile access gateway.  In this case, the
      mobile node identifier, MN-ID, option MUST be included in the BRI
      and MUST contain the mobile access gateway identity

   o  The mobile access gateway address MAY be used as the Source
      Address in the packet's IPv6 header.


   The Acknowledge (A) bit in the Binding Revocation Indication requests
   the local mobility anchor to return a Binding Revocation
   Acknowledgement in response to this Binding Revocation Indication.
   As described in Section 6.3, the mobile access gateway SHOULD
   retransmit this Binding Revocation Indication to the local mobility
   anchor until it receives a matching Binding Revocation
   Acknowledgement or the BRIMaxRetransmitNumber is reached.  If the
   mobile access gateway does not set the (A) bit in the Binding
   Revocation Indication, the mobile access gateway MAY delete the
   mobile nodes IP tunnels immediately after sending the Binding
   Revocation Indication.







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9.2.2.  Receiving Binding Revocation Acknowledgement

   When the mobile access gateway receive a packet carrying a valid
   Binding Revocation Acknowledgement that was successfully processed
   according to Section 6.2, the mobile access gateway MUST validate the
   BRA as per the followings:

   o  When the mobile access gateway receive a packet carrying a valid
      Binding Revocation Acknowledgement and the Global (G) and Proxy
      MIPv6 (P) bits are set and the mobile nodes BCEs are in the state
      of Revocation in Progress, the mobile access gateway SHOULD
      examine the Status field as follows:

   o  If the Status field indicates that the Binding Revocation
      Indication was processed successfully, the mobile access gateway
      delete the MINDelayBRIs timer and the mobile nodes proxy bindings
      and all associated resources.

   o  If the Status field indicates (Global Revocation NOT Authorized),
      the mobile access gateway is not authorized to participate in a
      Per-Peer Global Revocation.  The mobile access gateway SHOULD NOT
      retry sending a Binding Revocation Indication with the Global (G)
      bit is set to the same local mobility agent.  The mobile access
      gateway should raise an alarm or log an event to indicate this
      rejection.


10.  Mobile Node Operation

10.1.  Receiving Binding Revocation Indication

   Upon receiving a packet carrying a Binding Revocation Indication, the
   mobile node MUST validate the packet according to Section 6.2 and the
   following tests:

   o  The mobile node MUST verify that the IP address in the Home
      Address option is its Home Address.

   o  If the Acknowledgement (A) bit is set in the Binding Revocation
      Indication and the MN has the BCE in registered state, the mobile
      node MUST send a Binding Revocation Acknowledgement.  However, in
      all other cases when the (A) bit is set in the BRI, the mobile
      node SHOULD send a Binding Revocation Acknowledgement.  In all
      cases, the mobile node MUST follow Section 10.2 when send a BRA
      using the appropriate status code.






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   o  The mobile node MUST verify that the (P) bit in the Binding
      Revocation Indication is NOT set.  If the (P) bit is set, the
      mobile node MUST silently discard the Binding Revocation
      Indication.

   o  If the Revocation Trigger field value is Administrative, the
      mobile node MUST not try to re-register with the home agent before
      contacting its home operator.

   o  If the mobile node has registered multiple care-of addresses with
      its home agent, the mobile node MUST verify which binding is being
      revoked by examining the content of the BRI message.  If the
      mobile node received a Binding Revocation Indication with a single
      or more than one BID options and its home address is in the Home
      Address option, the mobile node MUST consider its bindings
      identified in the Binding ID options are being revoked.

   o  If the mobile node has multi Care-of Addresses bindings with its
      home agent and received a Binding Revocation Indication, with only
      its home address in the Home Address option, the mobile node MUST
      consider all of its registered care-of addresses bindings with
      this home address have been revoked.


   The Revocation Trigger field value in the received Binding Revocation
   Indication could be used by the mobile node to define what action the
   mobile node could do to be able to register again and receive its IP
   mobility service, e.g. contacting its home operator.

10.2.  Sending Binding Revocation Acknowledgement

   When the mobile node receive a valid Binding Revocation Indication
   with the (A) bit is set from its home agent and while having this BCE
   in registered state, the mobile node MUST send a packet to its home
   agent containing a Binding Revocation Acknowledgement according to
   the procedure in Section 6.1 and the following:

   o  The mobile node MUST set the status field to successful to reflect
      that it has received the Binding Revocation Indication and
      acknowledge that its IP connectivity with its home agent has been
      revoked.

   o  The destination IP address of the IPv6 packet of the Binding
      Revocation Acknowledgement is set to the source IP address of the
      received Binding Revocation Indication.






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   o  If the mobile node receive a Binding Revocation Indication from a
      home agent which the mobile node does not have a registered
      binding with, the mobile node SHOULD silently discard the BRI
      message.  The mobile node should continue to use its assigned HoA
      to access its IP mobility service.


11.  Protocol Configuration Variables

   Any mobility entity which is allowed to invoke the binding revocation
   procedure by sending a Binding Revocation Indication message SHOULD
   allow the following variables to be configured.

   BRI Maximum Number of Retries (BRIMaxRetriesNumber)

      This variable specifies the maximum Number of times a mobility
      entity can retransmit a Binding Revocation Indication message
      before receiving a Binding Revocation Acknowledgement message.
      The default value for this parameter is 1.

   Minimum Delay Between BRI messages (MINDelayBRIs)

      This variable specifies the delay time in seconds before the
      revoking mobility entity retransmits a BRI message.  The default
      is 1 second but not less than 0.5 seconds.


12.  IANA Considerations

   This document defines two new messages BRI and BRA, as described in
   Section 5.1 and Section 5.2 by using two subtypes of the Mobile IPv6
   Generic Signalling Message which uses a MH type <TBD-IANA> as in
   [ID-MGSM] which requires the use of IPsec, The new subtype values
   <IANA-SUB1 and IANA-SUB2> needs to be assigned from the same
   numbering space as allocated for the other MGSM subtypes.


13.  Security Considerations

   The protocol described here uses the same security association
   between the MN and the HA or the MAG and the LMA that has been used
   to exchange the corresponding MIPv6 or Proxy MIPv6 BU and BA when the
   session was established.  This SPD of this IPsec SA MUST allow the MH
   type for the MGSM.

   However, in the case when the MAG sends a BRI message with the G bit
   is set, the LMA MUST verify that the MAG is authorized to use Per-
   Peer Global Revocation.



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14.  Acknowledgements

   The authors would like to thank Ryuji Wakikawa, Bruno Mongazon-
   Cazavet and Domagoj Premec for their review and comments of this
   draft and all colleagues who have supported the advancement of this
   draft effort.


15.  References

15.1.  Normative References

   [ID-DSMIP6]
              Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
              Routers", draft-ietf-mext-nemo-v4traversal-04 (work in
              progress), June 2008.

   [ID-MCoA]  Wakikawa, R., Devarapalli, V., Ernst, T., and K. Nagami,
              "Multiple Care-of Addresses Registration",
              draft-ietf-monami6-multiplecoa-08 (work in progress),
              May 2008.

   [ID-MGSM]  Haley, B. and S. Gundavelli, "Mobile IPv6 Generic
              Signaling Message",
              draft-haley-mext-generic-signaling-message-00 (work in
              progress), July 2008.

   [ID-PMIP6]
              Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6",
              draft-ietf-netlmm-proxymip6-18 (work in progress),
              May 2008.

   [ID-PMIP6-IPv4]
              Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-03
              (work in progress), May 2008.

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

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

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




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15.2.  Informative References

   [RFC3344]  Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
              August 2002.

   [RFC3543]  Glass, S. and M. Chandra, "Registration Revocation in
              Mobile IPv4", RFC 3543, August 2003.


Authors' Addresses

   Ahmad Muhanna
   Nortel
   2221 Lakeside Blvd.
   Richardson, TX  75082
   USA

   Email: amuhanna@nortel.com


   Mohamed Khalil
   Nortel
   2221 Lakeside Blvd.
   Richardson, TX  75082
   USA

   Email: mkhalil@nortel.com


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

   Email: sgundave@cisco.com


   Kuntal Chowdhury
   Starent Networks
   30 International Place
   Tewksbury, MA  01876
   USA

   Email: kchowdhury@starentnetworks.com






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   Parviz Yegani
   Cisco Systems
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Email: pyegani@cisco.com












































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