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

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 relevant.

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", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 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.

Authors' Addresses

   Sri Gundavelli
   170 West Tasman Drive
   San Jose, CA  95134


   Mark Townsley
   L'Atlantis, 11, Rue Camille Desmoulins


Ole Troan


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