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Internet Engineering Task Force (IETF)                          R. DromsRequest for Comments: 7346                                         CiscoUpdates:4007,4291                                          August 2014Category: Standards TrackISSN: 2070-1721IPv6 Multicast Address ScopesAbstract   This document updates the definitions of IPv6 multicast scopes and   therefore updates RFCs 4007 and 4291.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 inSection 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/rfc7346.Droms                        Standards Track                    [Page 1]

RFC 7346              IPv6 Multicast Address Scopes          August 2014Copyright Notice   Copyright (c) 2014 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.  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.   This document may contain material from IETF Documents or IETF   Contributions published or made publicly available before November   10, 2008.  The person(s) controlling the copyright in some of this   material may not have granted the IETF Trust the right to allow   modifications of such material outside the IETF Standards Process.   Without obtaining an adequate license from the person(s) controlling   the copyright in such materials, this document may not be modified   outside the IETF Standards Process, and derivative works of it may   not be created outside the IETF Standards Process, except to format   it for publication as an RFC or to translate it into languages other   than English.1.  IntroductionRFC 4291 [RFC4291] defines "scop" as "a 4-bit multicast scope value   used to limit the scope of the multicast group" and defines "scop 3"   as "reserved".  The multicast protocol specification in [MPL] desires   to use multicast scop 3 to transport multicast traffic scoped to a   network of nodes connected in a mesh.  This scop value is used to   accommodate a multicast scope that is greater than Link-Local but is   also automatically determined by the network architecture.Droms                        Standards Track                    [Page 2]

RFC 7346              IPv6 Multicast Address Scopes          August 20142.  Definition of IPv6 Multicast Address Scopes (UpdatesRFC 4291)   The following table updates the definitions in [RFC4291]:      +------+--------------------------+-------------------------+      | scop | NAME                     | REFERENCE               |      +------+--------------------------+-------------------------+      |  0   | Reserved                 | [RFC4291],RFC 7346     |      |  1   | Interface-Local scope    | [RFC4291],RFC 7346     |      |  2   | Link-Local scope         | [RFC4291],RFC 7346     |      |  3   | Realm-Local scope        | [RFC4291],RFC 7346     |      |  4   | Admin-Local scope        | [RFC4291],RFC 7346     |      |  5   | Site-Local scope         | [RFC4291],RFC 7346     |      |  6   | Unassigned               |                         |      |  7   | Unassigned               |                         |      |  8   | Organization-Local scope | [RFC4291],RFC 7346     |      |  9   | Unassigned               |                         |      |  A   | Unassigned               |                         |      |  B   | Unassigned               |                         |      |  C   | Unassigned               |                         |      |  D   | Unassigned               |                         |      |  E   | Global scope             | [RFC4291],RFC 7346     |      |  F   | Reserved                 | [RFC4291],RFC 7346     |      +------+--------------------------+-------------------------+   The following change is applied toSection 2.7 of [RFC4291].   OLD:      Admin-Local scope is the smallest scope that must be      administratively configured, i.e., not automatically derived from      physical connectivity or other, non-multicast-related      configuration.   NEW:      Interface-Local, Link-Local, and Realm-Local scope boundaries are      automatically derived from physical connectivity or other non-      multicast-related configurations.  Global scope has no boundary.      The boundaries of all other non-reserved scopes of Admin-Local or      larger are administratively configured.  For reserved scopes, the      way of configuring their boundaries will be defined when the      semantics of the scope are defined.      According toRFC 4007 [RFC4007], the zone of a Realm-Local scope      must fall within zones of larger scope.  Because the zone of a      Realm-Local scope is configured automatically while the zones of      larger scopes are configured manually, care must be taken in theDroms                        Standards Track                    [Page 3]

RFC 7346              IPv6 Multicast Address Scopes          August 2014      definition of those larger scopes to ensure that the inclusion      constraint is met.      Realm-Local scopes created by different network technologies are      considered to be independent and will have different zone indices      (seeSection 6 of [RFC4007]).  A router with interfaces on links      using different network technologies does not forward traffic      between the Realm-Local multicast scopes defined by those      technologies.3.  Definition of Realm-Local Scopes   The definition of any Realm-Local scope for a particular network   technology should be published in an RFC.  For example, such a scope   definition would be appropriate for publication in an "IPv6-over-foo"   RFC.   Any RFCs that include the definition of a Realm-Local scope will be   added to the IANA "IPv6 Multicast Address Scopes" registry under the   Realm-Local scope entry, and those specifications must include such a   request in their IANA Considerations.Section 5 of this document gives the definition of scop 3 for IEEE   802.15.4 [IEEE802.15.4] networks.4.  Definition of Automatic and Administratively Configured Scopes    (UpdatesRFC 4007)Section 5 of RFC 4007 [RFC4007] andSection 2.7 of RFC 4291 [RFC4291]   disagree on the way in which multicast scop 3 is configured.  To   resolve that disagreement, the last bullet in the list inSection 5   of [RFC4007] is updated as follows:   OLD:   o  The boundaries of zones of a scope other than interface-local,      link-local, and global must be defined and configured by network      administrators.   NEW:   o  The boundaries of zones of a scope are defined by the IPv6      addressing architecture [RFC4291] and updated byRFC 7346.Droms                        Standards Track                    [Page 4]

RFC 7346              IPv6 Multicast Address Scopes          August 20145.  Definition of Realm-Local Scope for IEEE 802.15.4   When used in an IP-over-IEEE802.15.4 network, scop 3 is defined to   include all interfaces sharing a Personal Area Network Identifier   (PAN ID).6.  IANA Considerations   IANA has established a sub-registry titled "IPv6 Multicast Address   Scopes" in the existing "IPv6 Multicast Address Space Registry".  The   new registry has been populated with the scop values given inSection 2.  New definitions for scop values will be made following   the "IETF Review" policy [RFC5226].   For each future RFC that defines a Realm-Local scope for new network   technologies (scop 3), IANA will add a reference to the defining   document in the "IPv6 Multicast Address Scopes" registry.  Such RFCs   are expected to make an explicit request to IANA for inclusion in the   registry.   IANA has included a note on the top of the "IPv6 Multicast Address   Scopes" registry:      The definition of any Realm-Local scope for a particular network      technology should be published in an RFC.  For example, such a      scope definition would be appropriate for publication in an 'IPv6-      over-foo' RFC.      Any RFCs that define a Realm-Local scope will be listed in this      registry as an additional reference in the Realm-Local scope      entry.  Such RFCs are expected to make an explicit request to IANA      for inclusion in this registry.7.  Acknowledgments   Robert Cragie, Kerry Lynn, Jinmei Tatuya, Dave Thaler, and Stig   Venaas all contributed text and/or review to ensure that the updates   toRFC 4007 andRFC 4291 are correct.8.  Security Considerations   This document has no security considerations beyond those inRFC 4007   [RFC4007] andRFC 4291 [RFC4291].Droms                        Standards Track                    [Page 5]

RFC 7346              IPv6 Multicast Address Scopes          August 20149.  References9.1.  Normative References   [RFC4007]  Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and              B. Zill, "IPv6 Scoped Address Architecture",RFC 4007,              March 2005.   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing              Architecture",RFC 4291, February 2006.9.2.  Informative References   [IEEE802.15.4]              IEEE Computer Society, "IEEE Std. 802.15.4-2006", October              2006.   [MPL]      Hui, J. and R. Kelsey, "Multicast Protocol for Low power              and Lossy Networks (MPL)", Work in Progress, April 2014.   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              May 2008.Author's Address   Ralph Droms   Cisco   1414 Massachusetts Avenue   Boxborough, MA  01719   USA   Phone: +1 978 936 1674   EMail: rdroms.ietf@gmail.comDroms                        Standards Track                    [Page 6]