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rfc:rfc6747

Internet Research Task Force (IRTF) RJ Atkinson Request for Comments: 6747 Consultant Category: Experimental SN Bhatti ISSN: 2070-1721 U. St Andrews

                                                         November 2012
                 Address Resolution Protocol (ARP)
   for the Identifier-Locator Network Protocol for IPv4 (ILNPv4)

Abstract

 This document defines an Address Resolution Protocol (ARP) extension
 to support the Identifier-Locator Network Protocol for IPv4 (ILNPv4).
 ILNP is an experimental, evolutionary enhancement to IP.  This
 document is a product of the IRTF Routing Research Group.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for examination, experimental implementation, and
 evaluation.
 This document defines an Experimental Protocol for the Internet
 community.  This document is a product of the Internet Research Task
 Force (IRTF).  The IRTF publishes the results of Internet-related
 research and development activities.  These results might not be
 suitable for deployment.  This RFC represents the individual
 opinion(s) of one or more members of the Routing Research Group of
 the Internet Research Task Force (IRTF).  Documents approved for
 publication by the IRSG are not a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6747.

Atkinson & Bhatti Experimental [Page 1] RFC 6747 ILNPv4 ARP November 2012

Copyright Notice

 Copyright (c) 2012 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.
 This document may not be modified, and derivative works of it may not
 be created, except to format it for publication as an RFC or to
 translate it into languages other than English.

Table of Contents

 1. Introduction ....................................................3
    1.1. ILNP Document Roadmap ......................................3
    1.2. Terminology ................................................5
 2. ARP Extensions for ILNPv4 .......................................5
    2.1. ILNPv4 ARP Request Packet Format ...........................5
    2.2. ILNPv4 ARP Reply Packet Format .............................7
    2.3. Operation and Implementation of ARP for ILNPv4 .............8
 3. Security Considerations .........................................9
 4. IANA Considerations .............................................9
 5. References .....................................................10
    5.1. Normative References ......................................10
    5.2. Informative References ....................................11
 6. Acknowledgements ...............................................11

Atkinson & Bhatti Experimental [Page 2] RFC 6747 ILNPv4 ARP November 2012

1. Introduction

 This document is part of the ILNP document set, which has had
 extensive review within the IRTF Routing RG.  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
 controversial.
 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 multihoming, node multihoming,
 site/subnet mobility, node mobility) are also active concerns at
 present.  Several different classes of evolution are being
 considered by the Internet research and 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. ILNP Document Roadmap

 This document describes extensions to ARP for use with
 ILNPv4.
 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

Atkinson & Bhatti Experimental [Page 3] RFC 6747 ILNPv4 ARP November 2012

 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 [RFC6741].  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) [RFC6740] is the main architectural description of ILNP,
       including the concept of operations.
    b) [RFC6741] describes engineering and implementation
       considerations that are common to both ILNPv4 and ILNPv6.
    c) [RFC6742] defines additional DNS resource records that
       support ILNP.
    d) [RFC6743] 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) [RFC6744] 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) [RFC6745] defines 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.
    g) [RFC6746] 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.
    h) [RFC6748] 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.

Atkinson & Bhatti Experimental [Page 4] RFC 6747 ILNPv4 ARP November 2012

1.2. 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 [RFC2119].

2. ARP Extensions for ILNPv4

 ILNP for IPv4 (ILNPv4) is merely a different instantiation of the
 ILNP architecture, so it retains the crisp distinction between the
 Locator and the Identifier.  As with ILNPv6, only the Locator
 values are used for routing and forwarding ILNPv4 packets
 [RFC6740].  As with ILNP for IPv6 (ILNPv6), when ILNPv4 is used
 for a network-layer session, the upper-layer protocols (e.g.,
 TCP/UDP pseudo-header checksum, IPsec Security Association) bind
 only to the Identifiers, never to the Locators [RFC6741].
 However, just as the packet format for IPv4 is different to IPv6,
 so the engineering details for ILNPv4 are different also.  While
 ILNPv6 is carefully engineered to be fully backwards-compatible
 with IPv6 Neighbor Discovery, ILNPv4 relies upon an extended
 version of the Address Resolution Protocol (ARP) [RFC826], which
 is defined here.  While ILNPv4 could have been engineered to avoid
 changes in ARP, that would have required that the ILNPv4 Locator
 (i.e., L32) have slightly different semantics, which was
 architecturally undesirable.
 The packet formats used are direct extensions of the existing
 widely deployed ARP Request (OP code 1) and ARP Reply (OP code 2)
 packet formats.  This design was chosen for practical engineering
 reasons (i.e., to maximise code reuse), rather than for maximum
 protocol design purity.
 We anticipate that ILNPv6 is much more likely to be widely
 implemented and deployed than ILNPv4.  However, having a clear
 definition of ILNPv4 helps demonstrate the difference between
 architecture and engineering, and also demonstrates that the
 common ILNP architecture can be instantiated in different ways
 with different existing network-layer protocols.

2.1. ILNPv4 ARP Request Packet Format

 The ILNPv4 ARP Request is an extended version of the widely
 deployed ARP Request (OP code 1).  For experimentation purposes,
 the ILNPv4 ARP Request OP code uses decimal value 24.  It is
 important to note that decimal value 24 is a pre-defined,
 shared-use experimental OP code for ARP [RFC5494], and is not

Atkinson & Bhatti Experimental [Page 5] RFC 6747 ILNPv4 ARP November 2012

 uniquely assigned to ILNPv4 ARP Requests.  The ILNPv4 ARP Request
 extension permits the Node Identifier (NID) values to be carried
 in the ARP message, in addition to the node's 32-bit Locator
 (L32) values [RFC6742].
      0        7        15       23       31
      +--------+--------+--------+--------+
      |       HT        |        PT       |
      +--------+--------+--------+--------+
      |  HAL   |  PAL   |        OP       |
      +--------+--------+--------+--------+
      |         S_HA (bytes 0-3)          |
      +--------+--------+--------+--------+
      | S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
      +--------+--------+--------+--------+
      |S_L32 (bytes 2-3)|S_NID (bytes 0-1)|
      +--------+--------+--------+--------+
      |         S_NID (bytes 2-5)         |
      +--------+--------+--------+--------+
      |S_NID (bytes 6-7)| T_HA (bytes 0-1)|
      +--------+--------+--------+--------+
      |         T_HA (bytes 3-5)          |
      +--------+--------+--------+--------+
      |         T_L32 (bytes 0-3)         |
      +--------+--------+--------+--------+
      |         T_NID (bytes 0-3)         |
      +--------+--------+--------+--------+
      |         T_NID (bytes 4-7)         |
      +--------+--------+--------+--------+
  Figure 2.1: ILNPv4 ARP Request packet format
 In Figure 2.1, the fields are as follows:
   HT      Hardware Type (*)
   PT      Protocol Type (*)
   HAL     Hardware Address Length (*)
   PAL     Protocol Address Length (uses new value 12)
   OP      Operation Code (uses experimental value OP_EXP1=24)
   S_HA    Sender Hardware Address (*)
   S_L32   Sender L32  (* same as Sender IPv4 address for ARP)
   S_NID   Sender Node Identifier (8 bytes)
   T_HA    Target Hardware Address (*)
   T_L32   Target L32  (* same as Target IPv4 address for ARP)
   T_NID   Target Node Identifier (8 bytes)

Atkinson & Bhatti Experimental [Page 6] RFC 6747 ILNPv4 ARP November 2012

 The changed OP code indicates that this is ILNPv4 and not IPv4.  The
 semantics and usage of the ILNPv4 ARP Request are identical to the
 existing ARP Request (OP code 2), except that the ILNPv4 ARP Request
 is sent only by nodes that support ILNPv4.
 The field descriptions marked with "*" should have the same values as
 for ARP as used for IPv4.

2.2. ILNPv4 ARP Reply Packet Format

 The ILNPv4 ARP Reply is an extended version of the widely deployed
 ARP Reply (OP code 2).  For experimentation purposes, the ILNPv4 ARP
 Request OP code uses decimal value 25.  It is important to note that
 decimal value 25 is a pre-defined, shared-use experimental OP code
 for ARP [RFC5494], and is not uniquely assigned to ILNPv4 ARP
 Requests.  The ILNPv4 ARP Reply extension permits the Node Identifier
 (NID) values to be carried in the ARP message, in addition to the
 node's 32-bit Locator (L32) values [RFC6742].
      0        7        15       23       31
      +--------+--------+--------+--------+
      |       HT        |        PT       |
      +--------+--------+--------+--------+
      |  HAL   |  PAL   |        OP       |
      +--------+--------+--------+--------+
      |         S_HA (bytes 0-3)          |
      +--------+--------+--------+--------+
      | S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
      +--------+--------+--------+--------+
      |S_L32 (bytes 2-3)|S_NID (bytes 0-1)|
      +--------+--------+--------+--------+
      |         S_NID (bytes 2-5)         |
      +--------+--------+--------+--------+
      |S_NID (bytes 6-7)| T_HA (bytes 0-1)|
      +--------+--------+--------+--------+
      |         T_HA (bytes 3-5)          |
      +--------+--------+--------+--------+
      |         T_L32 (bytes 0-3)         |
      +--------+--------+--------+--------+
      |         T_NID (bytes 0-3)         |
      +--------+--------+--------+--------+
      |         T_NID (bytes 4-7)         |
      +--------+--------+--------+--------+
  Figure 2.2: ILNPv4 ARP Reply packet format

Atkinson & Bhatti Experimental [Page 7] RFC 6747 ILNPv4 ARP November 2012

 In Figure 2.2, the fields are as follows:
   HT      Hardware Type (*)
   PT      Protocol Type (*)
   HAL     Hardware Address Length (*)
   PAL     Protocol Address Length (uses new value 12)
   OP      Operation Code (uses experimental value OP_EXP2=25)
   S_HA    Sender Hardware Address (*)
   S_L32   Sender L32  (* same as Sender IPv4 address for ARP)
   S_NID   Sender Node Identifier (8 bytes)
   T_HA    Target Hardware Address (*)
   T_L32   Target L32  (* same as Target IPv4 address for ARP)
   T_NID   Target Node Identifier (8 bytes)
 The changed OP code indicates that this is ILNPv4 and not IPv4.  The
 semantics and usage of the ILNPv4 ARP Reply are identical to the
 existing ARP Reply (OP code 2), except that the ILNPv4 ARP Reply is
 sent only by nodes that support ILNPv4.
 The field descriptions marked with "*" should have the same values as
 for ARP as used for IPv4.

2.3. Operation and Implementation of ARP for ILNPv4

 The operation of ARP for ILNPv4 is almost identical to that for IPv4.
 Essentially, the key differences are:
    a) where an IPv4 ARP Request would use IPv4 addresses, an ILNPv4
       ARP Request MUST use:
       1. a 32-bit L32 value (_L32 suffixes in Figures 2.1 and 2.2)
       2. a 64-bit NID value (_NID suffixes in Figures 2.1 and 2.2)
    b) where an IPv4 ARP Reply would use IPv4 addresses, an ILNPv4 ARP
       Reply MUST use:
       1. a 32-bit L32 value (_L32 suffixes in Figures 2.1 and 2.2)
       2. a 64-bit NID value (_NID suffixes in Figures 2.1 and 2.2)
 As the OP codes 24 and 25 are distinct from ARP for IPv4, but the
 packet formats in Figures 2.1 and 2.2 are, effectively, extended
 versions of the corresponding ARP packets.  It should be possible to
 implement this extension of ARP by extending existing ARP
 implementations rather than having to write an entirely new
 implementation for ILNPv4.  It should be emphasised, however, that OP
 codes 24 and 25 are for experimental use as defined in [RFC5494], and
 so it is possible that other experimental protocols could be using
 these OP codes concurrently.

Atkinson & Bhatti Experimental [Page 8] RFC 6747 ILNPv4 ARP November 2012

3. Security Considerations

 Security considerations for the overall ILNP architecture are
 described in [RFC6740].  Additional common security considerations
 applicable to ILNP are described in [RFC6741].  This section
 describes security considerations specific to the specific ILNPv4
 topics discussed in this document.
 The existing widely deployed Address Resolution Protocol (ARP) for
 IPv4 is a link-layer protocol, so it is not vulnerable to off-link
 attackers.  In this way, it is a bit different than IPv6 Neighbor
 Discovery (ND); IPv6 ND is a subset of the Internet Control Message
 Protocol (ICMP), which runs over IPv6.
 However, ARP does not include any form of authentication, so current
 ARP deployments are vulnerable to a range of attacks from on-link
 nodes.  For example, it is possible for one node on a link to forge
 an ARP packet claiming to be from another node, thereby "stealing"
 the other node's IPv4 address.  [RFC5227] describes several of these
 risks and some measures that an ARP implementation can use to reduce
 the chance of accidental IPv4 address misconfiguration and also to
 detect such misconfiguration if it should occur.
 This extension does not change the security risks that are inherent
 in using ARP.
 In situations where additional protection against on-link attackers
 is needed (for example, within high-risk operational environments),
 the IEEE standards for link-layer security [IEEE-802.1-AE] SHOULD be
 implemented and deployed.
 Implementers of this specification need to understand that the two OP
 code values used for these 2 extensions are not uniquely assigned to
 ILNPv4.  Other experimenters might be using the same two OP code
 values at the same time for different ARP-related experiments.
 Absent prior coordination among all users of a particular IP
 subnetwork, different experiments might be occurring on the same IP
 subnetwork.  So, implementations of these two ARP extensions ought to
 be especially defensively coded.

4. IANA Considerations

 This document makes no request of IANA.
 If in the future the IETF decided to standardise ILNPv4, then
 allocation of unique ARP OP codes for the two extensions above would
 be sensible as part of the IETF standardisation process.

Atkinson & Bhatti Experimental [Page 9] RFC 6747 ILNPv4 ARP November 2012

5. References

5.1. Normative References

 [IEEE-802.1-AE] IEEE, "Media Access Control (MAC) Security", IEEE
                 Standard 802.1 AE, 18 August 2006, IEEE, New York,
                 NY, 10016, USA.
 [RFC826]        Plummer, D., "Ethernet Address Resolution Protocol:
                 Or Converting Network Protocol Addresses to 48.bit
                 Ethernet Address for Transmission on Ethernet
                 Hardware", STD 37, RFC 826, November 1982.
 [RFC2119]       Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC5227]       Cheshire, S., "IPv4 Address Conflict Detection", RFC
                 5227, July 2008.
 [RFC5494]       Arkko, J. and C. Pignataro, "IANA Allocation
                 Guidelines for the Address Resolution Protocol
                 (ARP)", RFC 5494, April 2009.
 [RFC6740]       Atkinson, R. and S. Bhatti, "Identifier Locator
                 Network Protocol (ILNP) Architectural Description",
                 RFC 6740, November 2012.
 [RFC6741]       Atkinson, R. and S. Bhatti, "Identifier-Locator
                 Network Protocol (ILNP) Engineering and
                 Implementation Considerations", RFC 6741, November
                 2012.
 [RFC6742]       Atkinson, R., Bhatti, S., and S. Rose, "DNS Resource
                 Records for the Identifier-Locator Network Protocol
                 (ILNP)", RFC 6742, November 2012.
 [RFC6745]       Atkinson, R. and S. Bhatti,  "ICMP Locator Update
                 Message for the Identifier-Locator Network Protocol
                 for IPv4 (ILNPv4)", RFC 6745, November 2012.
 [RFC6746]       Atkinson, R. and S.Bhatti, "IPv4 Options for the
                 Identifier-Locator Network Protocol (ILNP)", RFC
                 6746, November 2012.

Atkinson & Bhatti Experimental [Page 10] RFC 6747 ILNPv4 ARP November 2012

5.2. Informative References

 [RFC4984]       Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed.,
                 "Report from the IAB Workshop on Routing and
                 Addressing", RFC 4984, September 2007.
 [RFC6743]       Atkinson, R. and S. Bhatti, "ICMPv6 Locator Update
                 Message", RFC 6743, November 2012.
 [RFC6744]       Atkinson, R. and S. Bhatti, "IPv6 Nonce Destination
                 Option for the Identifier-Locator Network Protocol
                 for IPv6 (ILNPv6)", RFC 6744, November 2012.
 [RFC6748]       Atkinson, R. and S. Bhatti, "Optional Advanced
                 Deployment Scenarios for the Identifier-Locator
                 Network Protocol (ILNP)", RFC 6748, November 2012.

6. Acknowledgements

 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.

Atkinson & Bhatti Experimental [Page 11] RFC 6747 ILNPv4 ARP November 2012

Authors' Addresses

 RJ Atkinson
 Consultant
 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  KY16 9SX
 Scotland, UK
 EMail: saleem@cs.st-andrews.ac.uk

Atkinson & Bhatti Experimental [Page 12]

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