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Network Working Group                                     V. Devarapalli
Request for Comments: 5096                               Azaire Networks
Category: Standards Track                                  December 2007

                   Mobile IPv6 Experimental Messages

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.


   This document defines a new experimental Mobility Header message and
   a Mobility option that can be used for experimental extensions to the
   Mobile IPv6 protocol.

Table of Contents

   1. Introduction ....................................................1
   2. Terminology .....................................................2
   3. Experimental Mobility Header Message ............................3
   4. Experimental Mobility Option ....................................3
   5. Security Considerations .........................................4
   6. IANA Considerations .............................................5
   7. Acknowledgements ................................................5
   8. References ......................................................5
      8.1. Normative References .......................................5
      8.2. Informative References .....................................5

1.  Introduction

   When experimenting with a protocol or defining a new extension to a
   protocol, one needs either a protocol number, a new message, or an
   option to carry the information related to the experiment.  Most
   implementations end up using unassigned values for the new messages.
   Many times this creates problems when the same value is assigned
   through the IETF standards action, by IANA, or if the implementation
   gets deployed with these messages.  Therefore, it is considered a
   good practice to set aside some code points that identify the
   experimental protocols or messages for experimental purposes.  The
   need for experimental messages is shown in [3].

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RFC 5096              MIPv6 Experimental Messages          December 2007

   This document defines new messages for experimenting with extensions
   to the Mobile IPv6 protocol.  These messages should be strictly used
   for experiments.  Experiments that are successful should be
   standardized in the IETF.  An implementation MUST NOT be released or
   deployed with the experimental messages.

   This document defines a new Mobility Header message, which is the
   Experimental Mobility message that can be sent at any time by the
   mobile node, the home agent or the correspondent node.  Since
   Mobility Header messages cannot be combined and sent in one packet,
   there is always only one Mobility Header message in any Mobile IPv6
   packet.  Home agent or correspondent node implementations that do not
   recognize the mobility message type, discard the message and send a
   Binding Error message as described in [2], with the Status field set
   to 2 (unrecognized MH Type value).  Mobile nodes that do not
   recognize the mobility message type should discard the message and
   send an ICMP Parameter problem with code 0.

   This document also defines a new mobility option, the Experimental
   Mobility option, which can be carried in any Mobility Header message.
   Mobility options, by definition, can be skipped if an implementation
   does not recognize the mobility option type [2].

   The messages defined in this document can also be used for Network
   Mobility (NEMO) [4] and Proxy Mobile IPv6 [5] since these protocols
   also use Mobility Header messages.

   Experimental code points could potentially disrupt a deployed network
   when experiments using these code points are performed in the
   network.  Therefore, the network scope of support for experimental
   values should carefully be evaluated before deploying any experiment
   across extended network domains, such as the public Internet.

   Experimental mechanisms should only be used for actual
   experimentation.  By design, only a single code point is allocated
   for the message and another one for the option.  This limits the
   number of experiments among a set of peers to one at a time.  When
   experimental mechanisms are shown to be useful, and there is a desire
   to deploy them beyond the experiment they should be standardized and
   given new code points.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [1].

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RFC 5096              MIPv6 Experimental Messages          December 2007

3.  Experimental Mobility Header Message

   The Experimental Mobility Header message is based on the Mobility
   Header message defined in Section 6.1 of RFC 3775 [2].  There are no
   fields in the message beyond the required fields in the Mobility
   Header.  The 'MH Type' field in the Mobility Header indicates that it
   is an Experimental Mobility Header message.

   If no data is present in the message, two bytes of padding are
   required.  The 'Header Len' field in the Mobility Header is set to 0
   since the first 8 octets are excluded while calculating the length of
   the Mobility Header message.

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

   See RFC 3775 [2] for a description of the 'Payload Proto', 'Header
   Len', 'MH Type', 'Reserved', and 'Checksum' fields.

   The 'Message Data' field carries the data specific to the
   experimental protocol extension.  The total length of the message is
   indicated by the 'Header Len' field in the Mobility Header.

4.  Experimental Mobility Option

   The Experimental Mobility option can be included in any Mobility
   Header message.  If the Mobility Header message includes a Binding
   Authorization Data option [2], then the Experimental Mobility option
   should appear before the Binding Authorization Data option.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      |     Type      |   Length      |        Data .....

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RFC 5096              MIPv6 Experimental Messages          December 2007


      An 8-bit field indicating that it is an experimental mobility


      An 8-bit field indicating the length of the option in octets
      excluding the Type and Length fields.


      Data related to the experimental protocol extension.

5.  Security Considerations

   Protection for the Experimental Mobility Header message and Mobility
   option depends on the experiment that is being carried out and the
   kind of information that is being carried in the messages.  If these
   messages carry information that should not be revealed on the wire,
   or that can affect the binding cache entry at the home agent or the
   correspondent node, they should be protected in a manner similar to
   Binding Updates and Binding Acknowledgements.

   Security analyzers such as firewalls and network intrusion detection
   monitors often rely on unambiguous interpretations of the fields
   described in this document.  As new values for the fields are
   assigned, existing security analyzers that do not understand the new
   values may fail, resulting in either loss of connectivity, if the
   analyzer declines to forward the unrecognized traffic, or in loss of
   security if it does forward the traffic and the new values are used
   as part of an attack.

   When experimental code points are deployed within an administratively
   self-contained network domain, it must be ensured that each code
   point is used consistently to avoid interference between experiments.
   When experimental code points are used in traffic that crosses
   multiple administrative domains, the experimenters should assume that
   there is a risk that the same code points will be used simultaneously
   by other experiments and that there is a possibility that the
   experiments will interfere.  Particular attention should be given to
   security threats that such interference might create.  Please see RFC
   4727 for more details [6].

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RFC 5096              MIPv6 Experimental Messages          December 2007

6.  IANA Considerations

   The Experimental Mobility Header message, defined in Section 3, has
   been assigned the type value (11), allocated from the same space as
   the 'MH Type' field in the Mobility Header [2].

   The Experimental Mobility option, defined in Section 4, has been
   assigned the type value (18), allocated from the same space as
   Mobility Options [2].

7.  Acknowledgements

   The author would like to thank Jari Arkko and Basavaraj Patil with
   whom the contents of this document were discussed first.

8.  References

8.1.  Normative References

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

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

8.2.  Informative References

   [3]   Narten, T., "Assigning Experimental and Testing Numbers
         Considered Useful", BCP 82, RFC 3692, January 2004.

   [4]   Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
         "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
         January 2005.

   [5]   Gundavelli, S., "Proxy Mobile IPv6", Work in Progress, March

   [6]   Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, ICMPv6,
         UDP, and TCP Headers", RFC 4727, November 2006.

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RFC 5096              MIPv6 Experimental Messages          December 2007

Author's Address

   Vijay Devarapalli
   Azaire Networks
   4800 Great America Pkwy
   Santa Clara, CA 95054

   EMail: vijay.devarapalli@azairenet.com

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RFC 5096              MIPv6 Experimental Messages          December 2007

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