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Internet Draft                                               RJ Atkinson
draft-irtf-rrg-ilnp-icmpv6-01.txt                             Consultant
Category: Experimental                                          S Bhatti
Expires: 26 OCT 2012                                       U. St Andrews
                                                          March 26, 2012

                 ICMP Locator Update message for ILNPv6

Status of this Memo

   Distribution of this memo is unlimited.

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.

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   This Internet-Draft is submitted in full conformance with the
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   November 10, 2008.  The person(s) controlling the copyright in
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   document may not be modified outside the IETF Standards Process,
   and derivative works of it may not be created outside the IETF
   Standards Process, except to format it for publication as an RFC
   or to translate it into languages other than English.  This
   document may not be modified, and derivative works of it may not
   be created, except to publish it as an RFC or to translate it
   into languages other than English.

   Internet-Drafts are working documents of the Internet
   Engineering Task Force (IETF), its areas, and its working
   groups. Note that other groups may also distribute working
   documents as Internet-Drafts.

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   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other
   documents at any time. It is inappropriate to use Internet-Drafts
   as reference material or to cite them other than as "work in

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at

   This document is not on the IETF standards-track and does not
   specify any level of standard.  This document merely provides
   information for the Internet community.

   This document is part of the ILNP document set, which has had
   extensive review within the IRTF Routing Research Group.  ILNP
   is one of the recommendations made by the RG Chairs.  Separately,
   various refereed research papers on ILNP have also been published
   during this decade.  So the ideas contained herein have had much
   broader review than the IRTF Routing RG.  The views in this
   document were considered controversial by the Routing RG,
   but the RG reached a consensus that the document still should be
   published.  The Routing RG has had remarkably little consensus
   on anything, so virtually all Routing RG outputs are considered


   This note specifies an experimental ICMPv6 message type used with
   the Identifier-Locator Network Protocol (ILNP).  The
   Identifier-Locator Network Protocol (ILNP) is an experimental,
   evolutionary enhancement to IP.  This message is used to
   dynamically update Identifier/Locator bindings for an existing
   ILNP session.  This is a product of the IRTF Routing RG.

Table of Contents

    1. Introduction ...........................................3
    1.1  ILNP Document Roadmap.................................3
    1.2  ICMPv6 Locator Update.................................3
    1.3  Terminology...........................................3
    2. Syntax..................................................4
    2.1  Example ICMPv6 Locator Update message.................5
    3. Transport Protocol Effects..............................6
    4. Implementation Considerations...........................6

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    5. Backwards Compatibility.................................7
    6. Security Considerations ................................7
    7. IANA Considerations ....................................8
    8. References .............................................8

1. Introduction

   At present, the research and development community are examining
   various alternatives for evolving the Internet Architecture.  Several
   different classes of evolution are being considered.  One class is
   often called "Map and Encapsulate", where traffic would be mapped and
   then tunnelled through the inter-domain core of the Internet.
   Another class being considered is sometimes known as
   "Identifier/Locator Split".  This document relates to a proposal that
   is in the latter class of evolutionary approaches.

1.1 ILNP Document Roadmap

   The ILNP Architecture document [ILNP-ARCH] is the best place to start
   reading about ILNP.  ILNP has multiple possible instantiations.
   [ILNP-ENG] discusses engineering and implementation aspects common to
   all instances of ILNP.  A new IPv6 Destination Option used with
   ILNPv6 is defined in [ILNP-NONCEv6].  This document discusses a new
   ICMP for IPv6 message.  [ILNP-DNS] describes new Domain Name System
   (DNS) resource records used with ILNP.  Other documents describe ILNP
   for IPv4 (ILNPv4).

1.2 ICMPv6 Locator Update

   As described in [ILNP-ARCH] and [ILNP-ENG], an ILNP for IPv6 (ILNPv6)
   node might need to inform correspondent ILNPv6 nodes of changes to
   the set of valid Locator values.  The new ICMPv6 Locator Update
   message described in this document enables an ILNP-capable node to
   update its correspondents about the currently valid set of Locators
   valid to use in reaching the node sending this message.[RFC2460]

   This new ICMPv6 message MUST ONLY be used for ILNPv6 sessions.
   Authentication is always required, as described in the Security
   Considerations section later in this note.

   Some might consider any and all use of ICMP to be undesirable.  In
   that context, please note that while this specification uses ICMP, on
   grounds that this is a control message, there is no architectural
   difference between using ICMP and using some different framing, for
   example UDP.

1.3 Terminology

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   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

2. Syntax

   The ICMP for IPv6 message described in this section has ICMP Type XXX
   and is used ONLY with a current ILNPv6 session.  This message enables
   an ILNPv6 node to inform ILNPv6 correspondent nodes of changes to the
   active Locator set for the ILNPv6 node that originates this message.
   This particular ICMP for IPv6 message MUST ONLY be used with ILNPv6
   communications sessions.

    ICMPv6 Locator Update message

       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      |     Code      |           Checksum            |
      |  Num of Locs  |    RESERVED   |           RESERVED            |
      /                       Locator [1]                             /
      |        Preference [1]         |           Lifetime [1]        |
      /                       Locator [2]                             /
      |        Preference [2]         |           Lifetime [2]        |
      |                               .                               |
      |                               .                               |
      |                               .                               |

      ICMPv6 Locator Update fields:

         Type                  XXX

         Code                  0

         Checksum              The  16-bit one's complement of the one's
                               complement sum of the ICMP message,
                               starting with the ICMP Type.  For
                               computing the checksum, the Checksum
                               field is set to 0.

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         Num of  Locs          The number of 64-bit Locator values
                               that are advertised in this message.
                               This field MUST NOT be zero.

         Locator[i],           The 64-bit Locator values currently
          i = 1..Num of Locs   valid for the sending ILNPv6 node.

         Preference[i],        The preferability of each Locator[i],
          i = 1..Num of Locs   relative to other valid Locator[i]
                               values. The Preference numbers here are
                               identical, both in syntax and semantics,
                               to the Preference values for L64 records
                               as specified by [ILNP-DNS].

         Lifetime[i]           The maximum number of seconds that this
          i = 1..Num of Locs   particular Locator may be considered
                               valid.  Normally, this is identical
                               to the DNS lifetime of the
                               corresponding L64 record, if one

          RESERVED             A field reserved for possible future
                               use.  At present, the sender MUST
                               initialise this field to zero.
                               Receivers should ignore this field at
                               present.  The field might be used for
                               some protocol function in future.

   All ILNPv6 ICMP Locator Update messages MUST contain a valid ILNPv6
   Identifier option and MUST contain an ILNPv6 Nonce Option.

   ILNPv6 ICMP Locator Update messages also MAY be protected using IP
   Security for ILNP [ILNP-ENG] [RFC4301].  Deployments in high-threat
   environments SHOULD also protect ILNPv6 ICMP Locator Update messages
   using IP Security.  While IPsec ESP can protect a payload, no form of
   IPsec ESP is able to protect an IPv6 option that appears prior to the
   ESP header.

   Note that even when IP Security for ILNP is in use, the ILNP Nonce
   Option still MUST be present.  This simplifies protocol processing,
   and it also means that a receiver can perform the inexpensive check
   of the Nonce value before performing any (potentially expensive)
   cryptographic calculation.

2.1  Example ICMPv6 Locator Update message

This example shows the ICMPv6 syntax for the case where 2 Locator values

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are being indicated.

   |     Type      |     Code      |           Checksum            |
   |  Num of Locs  |    RESERVED   |           RESERVED            |
   /                       Locator [1]                             /
   |        Preference [1]         |           Lifetime [1]        |
   /                       Locator [2]                             /
   |        Preference [2]         |           Lifetime [2]        |

3.  Transport Protocol Effects

   This message has no impact on any transport protocol.

   The message may affect where packets for a given transport
   session are sent, but an ILNP design objective is to decouple
   transport-protocols from network-layer changes.

4. Implementation Considerations

   Implementers may use any internal implementation they wish,
   provided that the external appearance is the same as this
   implementation approach.

   To support ILNPv6, and to retain the incremental deployability
   and backwards compatibility needed, the network layer needs a
   mode bit in the Transport Control Block (or its equivalent) to
   track which IP sessions are using the classic IPv6 mode and which
   IP sessions are using the Identifier/Locator Split mode.

   Further, when supporting ILNPv4, nodes will need to support a
   Identifier Locator Communication Cache (ILCC) in the network
   layer as described in [ILNP-ENG].

   A node sending an ICMP Locator Update message MUST include all
   currently valid Locator values in that message.  A node receiving
   a valid ICMP Locator Update message MUST replace the previously
   current set of Locator values for that correspondent node in its
   own ILCC with the newly received set of Locator values.

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   Every implementation needs to support a large number of Locator
   values being sent or received in a single ICMP Locator Update
   message, because a multi-homed node or multi-homed site might
   have a large number of upstream links to different service
   providers, each with its own Locator value.

5.  Backwards Compatibility

   For all sessions operating in Identifier/Locator Split mode,
   inside each node the high-order 64-bits ("Locator") of the IPv6
   address field MUST be set to zero before calculating TCP or UDP
   checksums.  So, any changes in Locator values used on the wire
   will be invisible to the transport protocol.  In this mode,
   transport-layer checksums (e.g.  TCP pseudo-header checksum) will
   be calculated with both Source Locator and Destination Locator
   fields set to all zero.

   When ILNPv6 is not in use, the receiving IPv6 mode MUST discard
   the ICMP Locator Update packet without processing the packet.
   This is standard behaviour for a non-ILNPv6 node when receiving
   an ICMPv6 message with an unknown header field value.

6. Security Considerations

   Security considerations for the overall ILNP Architecture
   are described in [ILNP-ARCH].  Additional common security
   considerations are described in [ILNP-ENG].  This section
   describes security considerations specific to ILNPv6 topics
   discussed in this document.

   The ICMPv6 Locator Update message MUST ONLY be used for ILNPv6

   The ILNP Nonce Destination Option [ILNP-NONCEv6] MUST be present
   in packets containing an ICMPv6 Locator Update message.  Further,
   the received Nonce Destination Option MUST contain the correct
   nonce value for the packet to be accepted by the recipient and
   then passed to the ICMPv6 protocol for processing. If either of
   these requirements are not met, the received packet MUST be
   discarded as not authentic, and a security event SHOULD be logged
   by the system receiving the non-authentic packet.

   Sessions operating in higher risk environments SHOULD use IP
   Security for ILNP [ILNP-ENG] [RFC4301] *in addition* to the
   ILNPv6 Nonce Destination Option.  Use of IP Security for ILNP to

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   protect a packet does NOT permit the packet to be sent without
   the Nonce Destination Option.

   Implementations need to support the case where a single ICMP
   Locator Update message contains a large number of Locator and
   Preference values and ought not develop a security fault
   (e.g. stack overflow) due to a received message containing more
   Locator values than expected.

   If the ILNP Nonce value is predictable, then an off-path attacker
   might be able to forge data or control packets.  This risk also
   is mitigated by the existing common practice of IP Source Address
   filtering [RFC2827] [RFC3704].

7. IANA Considerations

   IANA is requested to assign a value, replacing the XXX, to the
   ICMP Type listed in Section 2, following the procedures in

   There are no other IANA actions for this document.

8.  References

   This document contains both normative and informative references.

8.1.  Normative References

   [ILNP-ARCH]  R. Atkinson and S. Bhatti, "ILNP Architecture",
                draft-irtf-rrg-ilnp-arch, March 2012.

   [ILNP-DNS]   R. Atkinson and S. Bhatti, "DNS Resource Records
                for ILNP", draft-irtf-rrg-ilnp-dns, March 2012.

   [ILNP-ENG]   R. Atkinson and S. Bhatti, "ILNP Engineering
                Considerations", draft-irtf-rrg-ilnp-eng,
                March 2012.

   [ILNP-NONCEv6] R. Atkinson and S. Bhatti, "Nonce Destination
                Option", draft-irtf-rrg-ilnp-noncev6,
                March 2012.

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

   [RFC2460]    S. Deering & R. Hinden, "Internet Protocol
                Version 6 Specification", RFC 2460,

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                December 1998.

   [RFC3704]    F. Baker, P. Savola, "Ingress Filtering for
                Multihomed Networks", RFC 3704, March 2004.

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

   [RFC4443]    A. Conta, S. Deering, and M. Gupta (Ed.),
                "Internet Control Message Protocol (ICMPv6)
                for the Internet Protocol Version 6 (IPv6)
                Specification", RFC 4443, March 2006.

8.2.  Informative References

   [RFC2827]   P. Ferguson and D. Senie, "Network Ingress
               Filtering: Defeating Denial of Service Attacks
               which employ IP Source Address Spoofing",
               RFC 2827, May 2000.


   Steve Blake, Stephane Bortzmeyer, Mohamed Boucadair, Noel
   Chiappa, Wes George, Steve Hailes, Joel Halpern, Mark Handley,
   Volker Hilt, Paul Jakma, Dae-Young Kim, Tony Li, Yakov Rehkter,
   Bruce Simpson, Robin Whittle and John Wroclawski (in alphabetical
   order) provided review and feedback on earlier versions of this
   document. Steve Blake provided an especially thorough review of
   an early version of the entire ILNP document set, which was
   extremely helpful. We also wish to thank the anonymous reviewers
   of the various ILNP papers for their feedback.


   This section is to be removed prior to publication.

   This document is written in English, not American.  So English
   spelling is used throughout, rather than American spelling.
   This is consistent with existing practice in several other RFCs,
   for example RFC-5887.

   This document tries to be very careful with history, in the
   interest of correctly crediting ideas to their earliest
   identifiable author(s).  So in several places the first published
   RFC about a topic is cited rather than the most recent published
   RFC about that topic.

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Author's Address

   RJ Atkinson
   San Jose, CA
   95125 USA

   Email: rja.lists@gmail.com

   SN Bhatti
   School of Computer Science
   University of St Andrews
   North Haugh, St Andrews,
   Fife, Scotland, UK
   KY16 9SX

   Email: saleem@cs.st-andrews.ac.uk

   Expires: 26 OCT 2012

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