Internet DRAFT - draft-haley-mext-generic-signaling-message

draft-haley-mext-generic-signaling-message





   MEXT Working Group                                       Brian Haley
   Internet Draft                                       Hewlett-Packard
   Intended status: Standards Track                      Sri Gundavelli
   Expires: December, 2008                                Cisco Systems
                                                          July 11, 2008



                  Mobile IPv6 Generic Signaling Message
             draft-haley-mext-generic-signaling-message-01.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
   have been or will be disclosed, and any of which he or she becomes
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Abstract

   This document specifies two new Mobility Header message types that
   allow Mobile IPv6 entities to send and receive generic signaling
   messages.











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Table of Contents

   1. Introduction...................................................2
   2. Terminology....................................................3
   3. Generic Signaling Messages.....................................3
      3.1 Generic Signaling Message..................................4
   4. Generic Signaling Sub-types....................................5
      4.1 Generic Signaling Option Sub-type..........................5
      4.2 Generic Signaling Request Sub-type.........................6
      4.3 Generic Signaling Acknowledgement Sub-type.................7
   5. Sending Generic Signaling Messages.............................8
      5.1 Sending Generic Signaling Option Messages..................8
      5.2 Sending Generic Signaling Request Messages.................8
      5.3 Sending Generic Signaling Acknowledgement Messages.........9
   6. Receiving Generic Signaling Messages...........................9
      6.1 Receiving Generic Signaling Option Messages...............10
      6.2 Receiving Generic Signaling Request Messages..............10
      6.2.1 Mobile Node Operation...................................10
      6.2.2 Home Agent Operation....................................10
      6.2.3 Retransmissions.........................................11
   7. Protocol Constants............................................11
   8. IANA Considerations...........................................11
   9. Security Considerations.......................................12
   10. References...................................................12
      10.1 Normative Reference......................................12
      10.2 Informative references...................................12
   Acknowledgments..................................................12
   Author's Addresses...............................................12


1. Introduction

   RFC 3775 [RFC3775] contains no provision for Mobile IPv6 entities,
   such as a home agent or mobile node, to send and receive signaling
   messages during a mobility session.

   This document describes a generic signaling message protocol that can
   be used by Mobile IPv6 entities for sending and receiving signaling
   events.  Two messages are defined - one that does not employ IPsec
   protection, and one that does.

   It also provides common semantics and a framework that can be used
   for defining new event types, and carrying them using the protocol
   defined in this document.

   The document does not define any specific events, or the
   corresponding actions that the receiver is required to do upon
   receiving an event.  The receiver actions specified in this document



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   are within the scope of the message delivery and acknowledgment that
   are common to all events carried using this messaging protocol.

2. Terminology

   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].

3. Generic Signaling Messages

   The messages described below follow the Mobility Header format
   specified in Section 6.1 of [RFC3775]:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Payload Proto |  Header Len   |   MH Type     |   Reserved    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |           Checksum            |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
    |                                                               |
    .                                                               .
    .                       Message Data                            .
    .                                                               .
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
























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3.1 Generic Signaling Messages

   The Generic Signaling messages are used by the home agent to notify
   the mobile node, or vice-versa, that there is an event that requires
   attention.  This packet is sent as described in Section 5.

   The Generic Signaling messages use the MH Type value (TBD1) or
   (TBD2).  When either value is indicated in the MH Type field, the
   format of the Message Data field in the Mobility Header 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
                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                   |           Sub-Type            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                     Sub-Type specific data                    .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Sub-Type

     A 16-bit unsigned integer.  This field describes the particular
     type of notification which is carried in the Generic Signaling
     message.

     This specification defines three Sub-types valid for the Generic
     Signaling messages.

   Sub-Type specific data

     Variable-length field containing data specific to the Sub-Type.
     This could be zero bytes in length.

     This specification defines three Sub-type data layouts valid for
     the Generic Signaling messages.

   Mobility options


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     Variable-length field of such length that the complete Mobility
     Header is an integer multiple of 8 octets long.  This field
     contains zero of more TLV-encoded mobility options.  The encoding
     and format of defined options MUST follow the format specified in
     Section 6.2 of [RFC3775].  The receiver MUST ignore and skip any
     options with it does not understand.

     This specification does not define any options valid for the
     Generic Signaling messages.

4. Generic Signaling Sub-types

4.1 Generic Signaling Option Sub-type

   The Generic Signaling Option sub-type specifies an un-bounded
   signaling message.  This packet is sent as described in Section 5.

   The Generic Signaling Option uses the sub-type value 0 (zero).  When
   this value is indicated in the Sub-Type field, there is no data
   contained in the Sub-Type Specific Data field in the Generic
   Signaling message, there are only Mobility Options, and the format 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   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 of more TLV-encoded mobility options.  The encoding
     and format of defined options MUST follow the format specified in
     Section 6.2 of [RFC3775].  The receiver MUST ignore and skip any
     options which it does not understand.

     This specification does not define any options valid for the
     Generic Signaling Option message.

   If no options are present in this message, no padding is necessary
   and the Header Len field in the Mobility Header will be set to 0.



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4.2 Generic Signaling Request Sub-type

   The Generic Signaling Request sub-type specifies a sequenced type of
   signaling message.  This packet is sent as described in Section 5.

   The Generic Signaling Request uses the sub-type value 1.  When this
   value is indicated in the Sub-Type field, the format of the Sub-Type
   Specific Data field in the Generic Signaling 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 Number        |A|           Reserved          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Sequence Number

     A 16-bit unsigned integer used by the receiving node to sequence
     Signaling Requests and by the sending node to match a returned
     Signaling Acknowledgement with this Signaling Request.

   Acknowledge (A)

     The Acknowledge (A) bit is set by the sender to request a Signaling
     Acknowledgement (Section 4.3) be returned upon receipt of a
     Signaling Request.

   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 of more TLV-encoded mobility options.  The encoding
     and format of defined options MUST follow the format specified in
     Section 6.2 of [RFC3775].  The receiver MUST ignore and skip any
     options with it does not understand.




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     This specification does not define any options valid for the
     Signaling Request message.

   If no options are present in this message, no padding is necessary
   and the Header Len field in the Mobility Header will be set to 0.

4.3 Generic Signaling Acknowledgement Sub-type

   The Generic Signaling Acknowledgement sub-type is used to acknowledge
   receipt of a Generic Signaling Request (Section 4.2).  This packet is
   sent as described in Section 5.

   The Generic Signaling Acknowledgement uses the Sub-Type value 2.
   When this value is indicated in the Sub-Type field, the format of the
   Sub-type Specific Data field in the Generic Signaling 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 Number        |    Status     |    Reserved   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                        Mobility options                       .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Sequence Number

     The sequence number in the Signaling Acknowledgement is copied from
     the sequence number field in the Signaling Request.  It is used by
     the receiving node in matching this Signaling Acknowledgement with
     an outstanding Signaling Request.

   Status

     8-bit unsigned integer indicating the disposition of the Signaling
     Request.  Values of the Status field less than 128 indicate that
     the Signaling Request was accepted by the receiving node.  Values
     greater than or equal to 128 indicate that the Signaling Request
     was rejected by the receiving node.  The following Status values
     are currently defined:

          0 Signaling Request accepted



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        128 Reason unspecified

        129 Administratively prohibited

        130 Insufficient resources

        131 Unsupported mobility option

        132 Not home agent for this mobile node

   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 of more TLV-encoded mobility options.  The encoding
     and format of defined options MUST follow the format specified in
     Section 6.2 of [RFC3775].  The receiver MUST ignore and skip any
     options with it does not understand.

     This specification does not define any options valid for the
     Signaling Request sub-type.

   If no options are present in this message, no padding is necessary
   and the Header Len field in the Mobility Header will be set to 0.

5. Sending Generic Signaling Messages

   When sending a Generic Signaling message, the sending node constructs
   the packet as it would any other Mobility Header, except:

     o The MH Type field MUST be set to (TBD1) if IPsec protection of
        the message is not required.

     o The MH Type field MUST be set to (TBD2) if IPsec protection of
        the message is required.  In this case, the Generic Signaling
        Request message MUST use the home agent to mobile node IPsec ESP
        authentication SA for integrity protection

5.1 Sending Generic Signaling Option Messages

   When sending a Generic Signaling Option, the sending node just adds
   mobility options to the message.

5.2 Sending Generic Signaling Request Messages

   When sending a Generic Signaling Request message, the sending node
   constructs the packet as specified in Section 5, except:




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     o The Acknowledge (A) bit MAY be set to indicate the receiver must
        send a Generic Signaling Acknowledgement in response to this
        Generic Signaling Request.

5.3 Sending Generic Signaling Acknowledgement Messages

   A Generic Signaling Acknowledgement message should be sent to
   indicate receipt of a Generic Signaling Request as follows:

     o If the Generic Signaling Request was discarded because it does
        not meet the requirements as specified in [RFC3775] described in
        Section 6, a Generic Signaling Acknowledgement MUST NOT be sent.
        Otherwise, the treatment depends on the below rule.

     o If the Acknowledgement (A) bit is set in the Generic Signaling
        Request, a Generic Signaling Acknowledgement MUST be sent.
        Otherwise, the treatment depends on the below rule.

     o If the Generic Signaling Request was discarded for any other
        reason, a Generic Signaling Acknowledgement SHOULD be sent.

   If the Source Address field of the IPv6 header that carried the
   Generic Signaling Request does not contain a unicast address, the
   Generic Signaling Acknowledgement MUST NOT be sent, and the Generic
   Signaling Request packet MUST be silently discarded.  Otherwise, the
   acknowledgement MUST be sent to the Source Address.

6. Receiving Generic Signaling Messages

   Upon receiving a Generic Signaling message, the Mobility Header MUST
   be verified as specified in [RFC3775], specifically:

     o The Checksum, MH type, Payload Proto and Header Len fields MUST
        meet the requirements of Section 9.2 of [RFC3775].

     o If the MH Type field is set to (TBD2) (IPsec protection of the
        message is required), then the packet MUST be covered by the
        home agent to mobile node IPsec ESP authentication SA for
        integrity protection.

   If the packet is dropped due to the above tests, the receiving node
   MUST follow the processing rules as Section 9.2 of [RFC3775].  For
   example, it MUST send a Binding Error message with the Status field
   set to 2 (unrecognized MH Type value) if it does not support the
   message type.

     o If the Generic Signaling message is valid according to the tests
        above, then it is processed according to the rules specific to
        the Sub-Type specified in the header.


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   Subsequent checks depend on the current mode of operation of the
   node.

6.1 Receiving Generic Signaling Option Messages

   If the Generic Signaling Option message is valid according to the
   tests in Section 6, then it is processed further as follows:

     o If the receiving node does not allow Generic Signaling Option
        messages, or does not support the type of Mobility Option in the
        message, it MUST reject the request and SHOULD silently discard
        the message.

   Subsequent checks depend on the current mode of operation of the
   node.

6.2 Receiving Generic Signaling Request Messages

   If the Generic Signaling Request message is valid according to the
   tests in Section 6, then it is processed further as follows:

     o If the receiving node does not allow Generic Signaling Request
        messages, it MUST reject the request and SHOULD return a Generic
        Signaling Acknowledgement to the sender in which the Status
        field is set to 129 (administratively prohibited).

     o If the receiving node does not support the type of Mobility
        Option in the Generic Signaling Request message, it MUST reject
        the request and SHOULD return a Generic Signaling
        Acknowledgement to the sender in which the Status field is set
        to 131 (unsupported mobility option).

   Subsequent checks depend on the current mode of operation of the
   node.

6.2.1 Mobile Node Operation

   If the mobile node rejects the Generic Signaling Request message for
   any other reason than specified in Section 6, it SHOULD return a
   Generic Signaling Acknowledgement to the home agent in which the
   Status field is set to 128 (reason unspecified).

6.2.2 Home Agent Operation

   If the receiving node is a home agent, it MUST perform these
   additional checks:



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     o If the home agent has no entry marked as a home registration in
        its Binding Cache for this mobile node, then this node MUST
        reject the request and SHOULD return a Generic Signaling
        Acknowledgement to the mobile node in which the Status field is
        set to 132 (not home agent for this mobile node).

     o If the home agent cannot process the Generic Signaling Request
        message because it is over-utilized, it MUST reject the request
        and SHOULD return a Generic Signaling Acknowledgement to the
        mobile node in which the Status field is set to 130
        (insufficient resources).

   If the home agent rejects the Generic Signaling Request message for
   any other reason, it SHOULD return a Generic Signaling
   Acknowledgement to the mobile node in which the Status field is set
   to 128 (reason unspecified).


6.2.3 Retransmissions

   If the sender has set the Acknowledge (A) bit in the Generic
   Signaling Request, but does not receive a Generic Signaling
   Acknowledgement, then it MAY retransmit the message, until a response
   is received.  The initial value for the retransmission timer is
   INITIAL_MH_SIGNALING_TIMEOUT.  The retransmissions by the sender MUST
   use an exponential back-off mechanism, in which the timeout period is
   doubled upon each retransmission, until either the sender gets a
   response from the target node, or the timeout period reaches the
   value MAX_MH_SIGNALING_TIMEOUT.


7. Protocol Constants

   INITIAL_MH_SIGNALING_TIMEOUT        5 seconds
   MAX_MH_SIGNALING_TIMEOUT           20 seconds


8. IANA Considerations

   Two new Mobility Header types are required for the following new
   message described in Section 2:

     (TBD1) Generic Signaling Message with
     (TBD2) Secure Generic Signaling Message

   New Generic Signaling Message Sub-Types are required for the
   following described in Section 4:



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     0 Generic Signaling Option
     1 Generic Signaling Request
     2 Generic Signaling Acknowledgement


9. Security Considerations

   Considerations have been made to support an unprotected Generic
   Signaling Message type, MH type (TBD1).  This message does not use
   any IPsec protection.

   In addition, a secure message, called the Secure Generic Signaling
   message, MH type (TBD2), is specified.  This message MUST use the
   home agent to mobile node IPsec ESP encryption SA for confidentiality
   protection, and MUST use the home agent to mobile node IPsec ESP
   authentication SA for integrity protection.  This message type SHOULD
   be used for signaling messages that update binding cache state on
   either system.

   The Secure Generic Signaling message MAY use the IPsec ESP SA in
   place for Binding Updates and Acknowledgements as specified in
   Section 5.1 of [RFC3775], in order to reduce the number of configured
   security associations.  This also gives the message authenticity
   protection.

10. References

10.1 Normative Reference

   [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 Arkko, J., "Mobility Support
         in IPv6", RFC 3775, June, 2004.

10.2 Informative references


Acknowledgments

   Thanks to Hui Deng, James Kempf and Vijay Devarapalli for their
   initial review of the draft.


Author's Addresses

   Brian Haley
   Hewlett-Packard Company
   110 Spitbrook Road


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   Nashua, NH 03062, USA
   Email: brian.haley@hp.com

   Sri Gundavelli
   Cisco Systems
   170 W.Tasman Drive
   San Jose, CA 95134, USA
   Email: sgundave@cisco.com


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Acknowledgement

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).














































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