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Internet Engineering Task Force (IETF)                     S. Gundavelli
Request for Comments: 6085                                   M. Townsley
Updates: 2464                                                   O. Troan
Category: Standards Track                                         W. Dec
ISSN: 2070-1721                                                    Cisco
                                                            January 2011

         Address Mapping of IPv6 Multicast Packets on Ethernet


   When transmitting an IPv6 packet with a multicast destination
   address, the IPv6 destination address is mapped to an Ethernet link-
   layer multicast address.  This document clarifies that a mapping of
   an IPv6 packet with a multicast destination address may in some
   circumstances map to an Ethernet link-layer unicast address.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in 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

Copyright Notice

   Copyright (c) 2011 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.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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RFC 6085           Unicast Transmission on Link Layer       January 2011

1.  Introduction

   "Transmission of IPv6 Packets over Ethernet Networks" ([RFC2464],
   Section 7) specifies how an IPv6 packet with a multicast destination
   address is mapped into an Ethernet link-layer address.  This document
   extends this mapping to explicitly allow for a mapping of an IPv6
   packet with a multicast destination address into an Ethernet link-
   layer unicast address, when it is clear that only one address is

   This mapping does not replace the mapping described in [RFC2464],
   Section 7.  The determination of the unicast Ethernet link-layer
   address and the construction of the outgoing IPv6 packet are out of
   scope for this document.

2.  Conventions

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

3.  Receiving IPv6 Multicast Packets

   An IPv6 node receiving an IPv6 packet with a multicast destination
   address and an Ethernet link-layer unicast address MUST NOT drop the
   packet as a result of the use of this form of address mapping.

4.  Security Considerations

   This document does not introduce any new security vulnerabilities.

5.  Acknowledgements

   The authors would like to acknowledge Bernard Aboba, Fred Baker, Wes
   Beebee, Ron Bonica, Olaf Bonness, Jean-Michel Combes, Ralph Droms,
   Alain Durand, Suresh Krishnan, Eric Levy-Abegnoli, Phil Roberts,
   Behcet Sarikaya, Hemant Singh, Mark Smith, Dave Thaler, Pascal
   Thubert, Stig Venaas, and Eric Voit for their contributions and
   discussions on this topic.

6.  Normative References

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

   [RFC2464]   Crawford, M., "Transmission of IPv6 Packets over Ethernet
               Networks", RFC 2464, December 1998.

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RFC 6085           Unicast Transmission on Link Layer       January 2011

Authors' Addresses

   Sri Gundavelli
   170 West Tasman Drive
   San Jose, CA  95134

   EMail: sgundave@cisco.com

   Mark Townsley
   L'Atlantis, 11, Rue Camille Desmoulins

   EMail: townsley@cisco.com

   Ole Troan

   EMail: ot@cisco.com

   Wojciech Dec
   Haarlerbergweg 13-19
   Amsterdam, Noord-Holland  1101 CH

   EMail: wdec@cisco.com

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