RFC 7346

IPv6 Multicast Address Scopes

📅 published August 2014, from ietf

RFC 7346: IPv6 Multicast Address Scopes 🦋

Okay bestie, here's the paperwork 💅

Series: Internet Engineering Task Force (IETF) ✨
Number: Request for Comments 7346 🎀
Author: Ralph Droms, from Cisco 🌸
Date: August 2014 📅
Category: Standards Track 👑
Updates: RFC 4007 and RFC 4291 💜
Obsoletes: nothing listed in the header 🙈
ISSN: 2070-1721

Abstract ✨

This one is short and sweet 🧚 It updates the definitions of IPv6 multicast scopes, and that's why it updates RFC 4007 and RFC 4291. Obviously. 💅

Status of This Memo 🌈

This is an Internet Standards Track document, so it's the real deal 🔥

It's a product of the IETF and it represents the IETF community's consensus. It got public review and the Internet Engineering Steering Group (IESG) approved it for publication. If you want more on Internet Standards, check out Section 2 of RFC 5741 📖

For the current status, any errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc7346 🦋

Copyright Notice 🎀

Legal stuff, but make it cute 🙈 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they're in effect on the date of publication. Please actually read those, because they lay out your rights and restrictions for this document. Code Components pulled out of this document must include the Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions, and they come with no warranty, same as the Simplified BSD License says 🔥

This document may contain material from IETF Documents or IETF Contributions that were published or made publicly available before November 10, 2008. Some of the copyright holders for that older material might not have given the IETF Trust permission to allow modifications outside the IETF Standards Process. So without a proper license from those copyright holders, this document can't be modified outside the IETF Standards Process, and derivative works of it can't be created outside it either. The one exceptions are formatting it for publication as an RFC or translating it into languages other than English 🌸

1. Introduction ✨

Okay so RFC 4291 [RFC4291] defines "scop" as "a 4-bit multicast scope value used to limit the scope of the multicast group," and it defines "scop 3" as "reserved." 🙈

Here's where it gets spicy The multicast protocol spec in [MPL] wants to use multicast scop 3 to carry multicast traffic scoped to a mesh-connected network of nodes. This scop value is meant to cover a scope that's bigger than Link-Local, but it's still determined automatically by the network architecture. It's giving main character energy 💅

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

The table below 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     |
+------+--------------------------+-------------------------+

Next, there's a change to Section 2.7 of [RFC4291] 🦋 Here's the old version:

   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.

And here's the new version, which is the one that matters now ✨

   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 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 the inclusion
   constraint is met.

   Realm-Local scopes created by different network technologies are
   considered to be independent and will have different zone indices
   (see Section 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 🌸

Any definition of a Realm-Local scope for a particular network technology should be published in an RFC. Like, an "IPv6-over-foo" RFC would be a good home for one 🧚

Any RFC that defines a Realm-Local scope gets added to the IANA "IPv6 Multicast Address Scopes" registry under the Realm-Local scope entry. Those specs also have to include that 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 (Updates RFC 4007) 🌈

Section 5 of RFC 4007 [RFC4007] and Section 2.7 of RFC 4291 [RFC4291] disagree on how multicast scop 3 gets configured 🙈 To settle it, the last bullet in the list in Section 5 of [RFC4007] gets updated like this.

Old bullet:

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 bullet:

o  The boundaries of zones of a scope are defined by the IPv6
   addressing architecture [RFC4291] and updated by RFC 7346.

5. Definition of Realm-Local Scope for IEEE 802.15.4 💖

When it's used in an IP-over-IEEE802.15.4 network, scop 3 is defined to include all interfaces that share a Personal Area Network Identifier (PAN ID) 🦋

6. IANA Considerations 👑

IANA set up a sub-registry called "IPv6 Multicast Address Scopes" inside the existing "IPv6 Multicast Address Space Registry." It got populated with the scop values from Section 2. New definitions for scop values follow the "IETF Review" policy [RFC5226] ✨

For each future RFC that defines a Realm-Local scope for new network technologies (scop 3), IANA adds a reference to the defining document in the "IPv6 Multicast Address Scopes" registry. Those RFCs are expected to make an explicit request to IANA to get into the registry 🎀

IANA also put a note at 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 make sure the updates to RFC 4007 and RFC 4291 are correct. Iconic group project 👑

8. Security Considerations 💀

Okay, deep breath, this part is serious This document has no security considerations beyond the ones in RFC 4007 [RFC4007] and RFC 4291 [RFC4291]. So go check those two, because that's where the security stuff lives 🔥

9. References 📚

9.1. 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.com

📦 where this page comes from

ietf: rfc7346 2014-08
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