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Internet Research Task Force (IRTF)                          RJ AtkinsonRequest for Comments: 6747                                    ConsultantCategory: Experimental                                         SN BhattiISSN: 2070-1721                                            U. St Andrews                                                           November 2012Address 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; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6747.Atkinson & Bhatti             Experimental                      [Page 1]

RFC 6747                       ILNPv4 ARP                  November 2012Copyright Notice   Copyright (c) 2012 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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 Contents1. Introduction ....................................................31.1. ILNP Document Roadmap ......................................31.2. Terminology ................................................52. ARP Extensions for ILNPv4 .......................................52.1. ILNPv4 ARP Request Packet Format ...........................52.2. ILNPv4 ARP Reply Packet Format .............................72.3. Operation and Implementation of ARP for ILNPv4 .............83. Security Considerations .........................................94. IANA Considerations .............................................95. References .....................................................105.1. Normative References ......................................105.2. Informative References ....................................116. Acknowledgements ...............................................11Atkinson & Bhatti             Experimental                      [Page 2]

RFC 6747                       ILNPv4 ARP                  November 20121.  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 thatAtkinson & 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 20121.2.  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 notAtkinson & 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 formatAtkinson & 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 20123.  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 20125.  References5.1.  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",RFC5227, 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)",RFC6746, November 2012.Atkinson & Bhatti             Experimental                     [Page 10]

RFC 6747                       ILNPv4 ARP                  November 20125.2.  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 2012Authors' 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.ukAtkinson & Bhatti             Experimental                     [Page 12]