Internet Engineering Task Force                                 R. Droms
Internet-Draft                                                     Cisco
Updates: RFC 4007, RFC 4291 (if approved)              November 11, 2013
Intended status: Standards Track
Expires: May 15, 2014

                     IPv6 Multicast Address Scopes


   This document updates the definitions of IPv6 multicast scopes.

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1.  Definition of IPv6 Multicast Address Scopes (Updates RFC 4291)

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   RFC 4291 [RFC4291] defines "scop is a 4-bit multicast scope value
   used to limit the scope of the multicast group." scop 3 is defined as
   "reserved" in RFC 4291.  The multicast protocol specification in
   draft-ietf-roll-trickle-mcast [I-D.ietf-roll-trickle-mcast] desires
   to use multicast scop 3 for transport of multicast traffic scoped to
   a network of nodes connected in a mesh.  The use of this scop value
   is to accommodate a multicast scope that is greater than Link-Local
   but is also automatically determined by the network architecture.

   The following table updates the definitions in RFC 4291:

   0  reserved

   1  Interface-Local scope

   2  Link-Local scope

   3  Realm-Local scope

   4  Admin-Local scope

   5  Site-Local scope

   6  (unassigned)

   7  (unassigned)

   8  Organization-Local scope

   9  (unassigned)

   A  (unassigned)

   B  (unassigned)

   C  (unassigned)

   D  (unassigned)

   E  Global scope

   F  reserved

   The following change is applied to section 2.7 of RFC 4291:


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         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


         Interface-Local, Link-Local, and Realm-Local scope
         boundaries are automatically derived from physical
         connectivity or other, non-multicast related configuration.
         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 is defined.

         According to RFC 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 the definition of those larger scopes
         to ensure that inclusion contraint is met.

2.  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"

   Any RFCs that include the definition of a Realm-Local scope will be
   listed in the IANA "IPv6 Multicast Address Scopes" registry.

   Section 4 gives the definition of scop 3 for IEEE 802.15.4
   [IEEE802.15.4] networks.

3.  Definition of automatic and administratively configured scopes
    (updates RFC 4007)

   Section 5 of RFC 4007 [RFC4007] and section 2.7 of RFC 4291 disagree
   about the way in which multicast scope 3 is configured.  To resolve
   that disagreement, change the last bullet in the list in section 5 of
   RFC 4007 as follows:

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     o  The boundaries of zones of a scope other than interface-local,
        link-local, and global must be defined and configured by network


     o  The boundaries of zones of a scope are defined by the IPv6
        addressing architecture [RFC4291].

4.  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 PAN ID.

5.  IANA Considerations

   IANA is asked to establish a sub-registry titled "IPv6 Multicast
   Address Scopes" in the existing "Internet Protocol version 6 (IPv6)
   Multicast Address Allocations" registry.  The "IPv6 Multicast Address
   Scopes" is to be populated with the scope values given in section 1,
   with a note associated with scope 3 listing all RFCs that define
   Realm-Local scoping rules that use scope 3.

6.  Acknowledgments

   Robert Cragie, Kerry Lynn, Jinmei Tatuya, Dave Thaler and Stig Venaas
   all contributed text and/or review to ensure that the updates to RFC
   4007 and RFC 4291 are correct

7.  Security Considerations

   This document has no security considerations beyond those in RFC 4291

8.  References

8.1.  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.

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8.2.  Informative References

              Hui, J. and R. Kelsey, "Multicast Protocol for Low power
              and Lossy Networks (MPL)", draft-ietf-roll-trickle-
              mcast-05 (work in progress), August 2013.

              IEEE Std 802.15.4-2006, "IEEE Standard for Information
              technology - Telecommunications and information exchange
              between systems - Local and metropolitan area networks -
              Specific requirements; Part 15.4: Wireless Medium Access
              Control (MAC) and Physical Layer (PHY) Specifications for
              Low-Rate Wireless Personal Area Networks (WPANs)", October

Author's Address

   Ralph Droms
   1414 Massachusetts Avenue
   Boxborough, MA  01719

   Phone: +1 978 936 1674

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