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Internet Research Task Force (IRTF)                          RJ AtkinsonRequest for Comments: 6745                                    ConsultantCategory: Experimental                                         SN BhattiISSN: 2070-1721                                            U. St Andrews                                                           November 2012ICMP Locator Update Message for theIdentifier-Locator Network Protocol for IPv4 (ILNPv4)Abstract   This note defines an experimental ICMP message type for IPv4 used   with the Identifier-Locator Network Protocol (ILNP).  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 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/rfc6745.Atkinson & Bhatti             Experimental                      [Page 1]

RFC 6745                       ILNPv4 ICMP                 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 ....................................................21.1. Document Roadmap ...........................................31.2. ICMPv4 Locator Update ......................................41.3. Terminology ................................................52. ICMP Locator Update Message for ILNPv4 ..........................53. Transport Protocol Effects ......................................84. Implementation Considerations ...................................85. Backwards Compatibility .........................................96. Security Considerations .........................................97. IANA Considerations ............................................108. References .....................................................108.1. Normative References ......................................108.2. Informative References ....................................119. Acknowledgements ...............................................111.  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.Atkinson & Bhatti             Experimental                      [Page 2]

RFC 6745                       ILNPv4 ICMP                 November 2012   At present, the Internet research and development community is   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.  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 is 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.Atkinson & Bhatti             Experimental                      [Page 3]

RFC 6745                       ILNPv4 ICMP                 November 2012   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) [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 it also defines a new IPv4 Identifier Option      used by ILNPv4 nodes.   g) [RFC6747] describes extensions to Address Resolution Protocol      (ARP) for use with ILNPv4.   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.1.2.  ICMPv4 Locator Update   As described in [RFC6740] and [RFC6741], 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 document.   Some might consider any and all use of ICMP to be undesirable.Atkinson & Bhatti             Experimental                      [Page 4]

RFC 6745                       ILNPv4 ICMP                 November 2012   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 NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [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 inSection 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]        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Atkinson & Bhatti             Experimental                      [Page 5]

RFC 6745                       ILNPv4 ICMP                 November 2012      ICMP Fields:         Type                  253                               This type value is taken fromSection 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                               [RFC6742].         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                               exists.          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.Atkinson & Bhatti             Experimental                      [Page 6]

RFC 6745                       ILNPv4 ICMP                 November 2012   NOTE WELL:  The ICMP Type value is allocated for shared               experimental use inSection 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 [RFC6741] [RFC4301].  Deployments in high-threat   environments SHOULD also protect ILNPv4 ICMP Locator Update messages   using IPsec.  While IPsec Encapsulating Security Payload (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.Atkinson & Bhatti             Experimental                      [Page 7]

RFC 6745                       ILNPv4 ICMP                 November 20123.  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, 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 [RFC6741].   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 multihomed node or multihomed 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], care should be taken when using with other protocols   also using experimental values.Atkinson & Bhatti             Experimental                      [Page 8]

RFC 6745                       ILNPv4 ICMP                 November 20125.  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.6.  Security Considerations   Security considerations for the overall ILNP Architecture are   described in [RFC6740].  Additional common security considerations   are described in [RFC6741].  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 [RFC6746] 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 [RFC6741] [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 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].Atkinson & Bhatti             Experimental                      [Page 9]

RFC 6745                       ILNPv4 ICMP                 November 20127.  IANA Considerations   This document makes no request of IANA.   If in the 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.8.  References8.1.  Normative References   [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate               Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC2460]   Deering, S. and R. Hinden, "Internet Protocol, Version 6               (IPv6) Specification",RFC 2460, December 1998.   [RFC4443]   Conta, A., Deering, S., and M. Gupta, Ed., "Internet               Control Message Protocol (ICMPv6) for the Internet               Protocol Version 6 (IPv6) Specification",RFC 4443, March               2006.   [RFC4301]   Kent, S. and K. Seo, "Security Architecture for the               Internet Protocol",RFC 4301, December 2005.   [RFC4727]   Murphy, S., "BGP Security Vulnerabilities Analysis",RFC4272, January 2006.   [RFC6740]   Atkinson, R. and S. Bhatti, "Identifier-Locator Network               Protocol (ILNP) Architectural Description",RFC 6740,               November 2012.   [RFC6747]   Atkinson, R. and S. Bhatti, "Address Resolution Protocol               (ARP) Extension for the Identifier-Locator Network               Protocol for IPv4 (ILNPv4)",RFC 6747, November 2012.   [RFC6741]   Atkinson, R. and S. Bhatti, "Identifier-Locator Network               Protocol (ILNP) Engineering and Implementation               Considerations",RFC 6741, 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 6745                       ILNPv4 ICMP                 November 20128.2.  Informative References   [RFC2827]   Ferguson, P. and D. Senie, "Network Ingress Filtering:               Defeating Denial of Service Attacks which employ IP               Source Address Spoofing",BCP 38,RFC 2827, May 2000.   [RFC3704]   Baker, F. and P. Savola, "Ingress Filtering for               Multihomed Networks",BCP 84,RFC 3704, March 2004.   [RFC4984]   Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report               from the IAB Workshop on Routing and Addressing",RFC4984, September 2007.   [RFC6742]   Atkinson, R., Bhatti, S. and S. Rose, "DNS Resource               Records for the Identifier-Locator Network Protocol               (ILNP)",RFC 6742, November 2012.   [RFC6748]   Atkinson, R. and S. Bhatti, "Optional Advanced Deployment               Scenarios for the Identifier-Locator Network Protocol               (ILNP)",RFC 6748, November 2012.   [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 2012.9.  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 6745                       ILNPv4 ICMP                 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]