Internet Draft                                           RJ Atkinson
draft-irtf-rrg-ilnp-icmpv4-06.txt                         Consultant
Expires: 10 JAN 2013                                       SN Bhatti
Category: Experimental                                 U. St Andrews
                                                        10 July 2012

                 ICMP Locator Update message for ILNPv4

Status of this Memo

   Distribution of this memo is unlimited.

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   provisions of BCP 78 and BCP 79.

   This document may contain material from IETF Documents or
   IETF Contributions published or made publicly available
   before November 10, 2008. The person(s) controlling the copyright
   in some of this material may not have granted the IETF Trust the
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   the person(s) controlling the copyright in such materials, this
   document may not be modified outside the IETF Standards Process,
   and derivative works of it may not be created outside the IETF
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   or to translate it into languages other than English.

   Internet-Drafts are working documents of the Internet Engineering
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   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 defines an experimental ICMP message type for IPv4 used
   with the Identifier-Locator Network Protocol (ILNP).  The
   Identifier-Locator Network Protocol (ILNP) is an experimental,
   evolutionary enhancement to IP.  The ICMP message defined herein
   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.............................2
     1.1  ILNP Document Roadmap..................3
     1.2  ICMPv4 Locator Update..................3
     1.3  Terminology............................3
     2. ICMP Locator Update message for ILNPv4...4
     3. Transport Protocol Effects...............5
     4. Implementation Considerations............6
     5. Backwards Compatibility..................6
     6. Security Considerations..................6
     7. IANA Considerations......................7
     8. References...............................7

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   At present, the Internet research and development community are
   exploring various approaches to evolving the Internet
   Architecture to solve a variety of issues including, but not
   limited to, scalability of inter-domain routing [RFC4984]. A wide
   range of other issues (e.g. site multi-homing, node multi-homing,
   site/subnet mobility, node mobility) are also active concerns at
   present. Several different classes of evolution are being
   considered by the Internet research & development community. 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.

   The Identifier Locator Network Protocol (ILNP) is a proposal for
   evolving the Internet Architecture.  It differs from the current
   Internet Architecture primarily by deprecating the concept of an
   IP Address, and instead defining two new objects, each having
   crisp syntax and semantics.  The first new object is the Locator,
   a topology-dependent name for a subnetwork.  The other new object
   is the Identifier, which provides a topology-independent name for
   a node.

1.1  Document roadmap

   This document describes a new ICMPv4 Locator Update message
   used by an ILNP node to inform its correspondent nodes
   of any changes to its set of valid Locators.

   The ILNP architecture can have more than one engineering
   instantiation. For example, one can imagine a "clean-slate"
   engineering design based on the ILNP architecture. In separate
   documents, we describe two specific engineering instances of
   ILNP. The term ILNPv6 refers precisely to an instance of ILNP that
   is based upon, and backwards compatible with, IPv6. The term ILNPv4
   refers precisely to an instance of ILNP that is based upon, and
   backwards compatible with, IPv4.

   Many engineering aspects common to both ILNPv4 and ILNPv6 are
   described in [ILNP-ENG]. A full engineering specification for
   either ILNPv6 or ILNPv4 is beyond the scope of this document.

   Readers are referred to other related ILNP documents for details
   not described here:

    a) [ILNP-ARCH] is the main architectural description of ILNP,

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       including the concept of operations.

    b) [ILNP-ENG] describes engineering and implementation
       considerations that are common to both ILNPv4 and ILNPv6.

    c) [ILNP-DNS] defines additional DNS resource records that
       support ILNP.

    d) [ILNP-ICMPv6] defines a new ICMPv6 Locator Update message
       used by an ILNP node to inform its correspondent nodes
       of any changes to its set of valid Locators.

    e) [ILNP-NONCEv6] defines a new IPv6 Nonce Destination Option
       used by ILNPv6 nodes (1) to indicate to ILNP correspondent
       nodes (by inclusion within the initial packets of an ILNP
       session) that the node is operating in the ILNP mode and
       (2) to prevent off-path attacks against ILNP ICMP messages.
       This Nonce is used, for example, with all ILNP ICMPv6
       Locator Update messages that are exchanged among ILNP
       correspondent nodes.

    f) [ILNP-v4OPTS] defines a new IPv4 Nonce Option used by ILNPv4
       nodes to carry a security nonce to prevent off-path attacks
       against ILNP ICMP messages and also defines a new IPv4
       Identifier Option used by ILNPv4 nodes.

    g) [ILNP-ARP] describes extensions to ARP for use with ILNPv4.

    h) [ILNP-ADV] describes optional engineering and deployment
       functions for ILNP. These are not required for the operation
       or use of ILNP and are provided as additional options.

1.2  ICMPv4 Locator Update

   As described in [ILNP-ARCH] and [ILNP-ENG], an ILNP for IPv4
   (ILNPv4) node might need to inform correspondent ILNPv4 nodes of
   changes to the set of valid Locator values. The new ICMPv4
   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] [RFC4443].

   This new ICMPv4 message MUST ONLY be used for ILNPv4 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.

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   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

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

2.  ICMP Locator Update message for ILNPv4

   The ICMP for IPv4 message described in this section has ICMP Type
   253 (as defined for experimental use in Section 8 of [RFC4727])
   and is used ONLY with a current ILNPv4 session. This message
   enables an ILNPv4 node to advertise changes to the active Locator
   set for the ILNPv4 node that originates this message to its
   unicast ILNP correspondent nodes.  It also enables those
   correspondents to acknowledge receipt of the advertisement.

   This particular ICMP for IPv4 message MUST ONLY be used with
   ILNPv4 sessions.  The Checksum field for this message is
   calculated identically as for any other IPv4 ICMP message.

    ICMP 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  |   Operation   |           RESERVED            |
      /                       Locator [1]                             /
      |        Preference [1]         |           Lifetime [1]        |
      /                       Locator [2]                             /
      |        Preference [2]         |           Lifetime [2]        |

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      ICMP Fields:

         Type                  253
                               This type value is taken from Section 8
                               of [RFC4727], and is allocated for
                               experimental use.

         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.

         Num of Locs           The number of 32-bit Locator values
                               that are advertised in this message.

         Locator[i],           The 32-bit Locator values currently
          i = 1..Num of Locs   valid for the sending ILNPv4 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 L32 records that are specified by

         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 L32 record, if one

          Operation            The value in this field indicates
                               whether this is a Locator Update
                               Advertisement (0x01) or a Locator
                               Update Acknowledgement (0x02).

          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.

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   NOTE WELL:  The ICMP TYPE value is allocated for shared
               experimental use in Section 8 of [RFC4727].
               It is not uniquely assigned to ILNPv4.  So
               implementations need to code particularly
               defensively as other IPv4 experiments might be
               using this same ICMP TYPE value for an
               entirely different purpose with a different
               ICMP packet format.

   The Operation field has value 1 (hexadecimal 0x01) for a Locator
   Update Advertisement.  The Operation field has value 2
   (hexadecimal 0x02) for a Locator Update Acknowledgement.  All
   other values of the Operation field are reserved for future use
   by future revisions of this specification.

   A node whose set of valid Locators has changed MUST send Locator
   Update Advertisement messages to each correspondent node for each
   active unicast ILNP session.  For unicast ILNP sessions, the
   receiver of a valid (i.e. authentication checks all passed,
   advertisement is received from a current correspondent node)
   Locator Update Advertisement addressed to the receiver MUST send
   a Locator Update Acknowledgement back to the sender of the
   Locator Update Advertisement.  The Acknowledgement message body
   is identical to the received Advertisement message body, except
   for the Operation value.

   All ILNPv4 ICMP Locator Update messages MUST contain a valid
   ILNPv4 Identifier option and MUST contain an ILNPv4 Nonce Option.

   ILNPv4 ICMP Locator Update messages also MAY be protected using
   IP Security for ILNP [ILNP-ENG] [RFC4301].  Deployments in
   high-threat environments SHOULD also protect ILNPv4 ICMP Locator
   Update messages using IP Security.  While IPsec ESP can protect a
   payload, no form of IPsec ESP is able to protect an IPv4 option
   that appears prior to the ESP header.  Note that even when IP
   Security for ILNP is in use, the ILNPv4 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.

3.  Transport Protocol Effects

   The ICMP Locator Update message has no impact on any transport protocol.

   The ICMP Locator Update message might affect where packets for
   a given transport-layer session are sent, but an ILNP design
   objective is to decouple transport protocols (e.g., TCP, UDP,

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   SCTP) and transport-layer sessions 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 ILNPv4, 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 IPv4 mode and which
   IP sessions are using ILNPv4 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.

   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.

   It should be noted that as the ICMP Type uses an experimental
   value from RFC4727 [RFC4727], care should be taken when using
   with other protocols also using experimental values.

5.  Backwards Compatibility

   This IPv4 ICMP message uses the same checksum calculations as any
   other IPv4 ICMP message.

   When ILNPv4 is not in use, the receiving IPv4 mode MUST discard
   the ICMP Locator Update packet without processing the packet.


   Security considerations for the overall ILNP Architecture
   are described in [ILNP-ARCH].  Additional common security

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   considerations are described in [ILNP-ENG].  This section
   describes security considerations specific to ILNPv4 topics
   discussed in this document.

   The ICMPv4 Locator Update message MUST ONLY be used for
   ILNPv4 sessions.

   The ILNPv4 Nonce Option [ILNP-v4OPTS] MUST be present in packets
   containing an ICMPv4 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 ICMPv4 protocol for processing. If either of these
   requirements are not met, the received packet MUST be discarded
   as a forgery, and a security event SHOULD be logged by the system
   receiving the non-authentic packet.

   ILNP sessions operating in higher risk environments SHOULD use
   IP Security for ILNP [ILNP-ENG] [RFC4301] *in addition* to the
   ILNPv4 Nonce Option.  Use of IP Security for ILNP to protect a
   packet does NOT permit the packet to be sent without the Nonce

   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].


   This document makes no request of IANA.

   If in future the IETF decided to standardise ILNPv4, then
   allocation of a unique ICMP Type for the Locator Update
   as part of the IETF standardisation process would be sensible.


   This document has both Normative and Informational References.

8.1  Normative References

   [RFC2119]    Bradner, S., "Key words for use in RFCs to

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                Indicate Requirement Levels", BCP 14, RFC 2119,
                March 1997.

   [RFC2460]    S. Deering & R. Hinden, "Internet Protocol
                Version 6 Specification", RFC2460,
                December 1998.

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

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

   [RFC4727]   B. Fenner, "Experimental Values in IPv4, IPv6, ICMPv4,
               ICMPv6, UDP, and TCP Headers", RFC 4727, Nov 2006.

   [ILNP-ARCH]    R.J. Atkinson & S.N. Bhatti,
                  "ILNP Architectural Description",
                  draft-irtf-rrg-ilnp-arch, 10 July 2012.

   [ILNP-ARP]   R.J. Atkinson & S.N. Bhatti, "ARP Extension for
                ILNPv4", draft-irtf-rrg-ilnp-arp, 10 July 2012.

   [ILNP-ENG]     R.J. Atkinson & S.N. Bhatti,
                  "ILNP Engineering and Implementation Considerations",
                  draft-irtf-rrg-ilnp-eng, 10 July 2012.

   [ILNP-v4OPTS] R.J. Atkinson & S.N. Bhatti,
                 "IPv4 Options for ILNP",
                 draft-irtf-rrg-ilnp-v4opts, 10 July 2012.

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.

   [RFC2780]  S. Bradner and V. Paxson,  "IANA Allocation
               Guidelines For Values In the Internet Protocol
               and Related Headers", RFC 2780, March 2000.

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

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   [RFC4884]  R. Bonica, D. Gan, D. Tappan, C. Pignataro,
               "Extended ICMP to Support Multi-Part Messages",
               RFC 4884, April 2007.

   [ILNP-DNS]     R.J. Atkinson, S.N. Bhatti, & S Rose,
                  "DNS Resource Records for ILNP",
                  draft-irtf-rrg-ilnp-dns, 10 July 2012.

   [ILNP-ADV]    R.J. Atkinson & S.N. Bhatti,
                 "Optional Advanced Deployment Scenarios for ILNP",
                 draft-irtf-rrg-ilnp-adv, 10 July 2012.

   [ILNP-ICMPv6]  R.J. Atkinson & S.N. Bhatti,
                  "ICMPv6 Locator Update message"
                  draft-irtf-rrg-ilnp-icmpv6, 10 July 2012.

   [ILNP-NONCEv6] R.J. Atkinson & S.N. Bhatti,
                 "IPv6 Nonce Destination Option for ILNPv6",
                 draft-irtf-rrg-ilnp-noncev6, 10 July 2012.


   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.

   Roy Arends provided expert guidance on technical and procedural
   aspects of DNS issues.


   This section is to be removed prior to publication.

   Please note that this document is written in British English, so
   British English spelling is used throughout. This is consistent
   with existing practice in several other RFCs, for example

   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

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   RFC about that topic.


   RJ Atkinson
   San Jose, CA
   95125 USA


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


   Expires: 10 JAN 2013

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