| Internet Engineering Task Force | R. Droms |
| Internet-Draft | Cisco |
| Updates: RFC 4291 (if approved) | November 04, 2013 |
| Intended status: Standards Track | |
| Expires: May 08, 2014 |
IPv6 Multicast Address Scopes
draft-ietf-6man-multicast-scopes-01.txt
This document updates the definitions of IPv6 multicast scopes.
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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; for example, all of the hosts and routers in a multi-link subnet RPL realm.
The following table updates the definitions in RFC 4291:
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 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.
The following change is applied to section 2.7 of RFC 4291:
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 listed in the IANA "IPv6 Multicast Address Scopes" registry.
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].
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:
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.
Robert Cragie, Kerry Lynn, Jinmei Tatuya, Dave Thaler and Stig Venaas all contributed to enuring that the updates to RFC 4007 and RFC 4291 are correct
This document has no security considerations beyond those in RFC 4291 [RFC4291].
| [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. |
| [I-D.ietf-roll-trickle-mcast] | Hui, J. and R. Kelsey, "Multicast Protocol for Low power and Lossy Networks (MPL)", Internet-Draft draft-ietf-roll-trickle-mcast-04, February 2013. |