Network Working Group                                          M. Cotton
Internet-Draft                                                     ICANN
Intended status: BCP                                            D. Meyer
Expires: December 26, 2008                                 June 24, May 7, 2009                                    November 3, 2008

         IANA Guidelines for IPv4 Multicast Address Assignments
                    draft-ietf-mboned-rfc3171bis-03
                    draft-ietf-mboned-rfc3171bis-04

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Abstract

   This document obsoletes RFC 3171.  It provides guidance for the
   Internet Assigned Numbers Authority (IANA) in assigning IPv4
   multicast addresses.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Definition of Current Assignment Practice  . . . . . . . . . .  3  4
   4.  Local Network Control Block (224.0.0/24) . . . . . . . . . . .  4
     4.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  4  5
   5.  Internetwork Control Block (224.0.1/24)  . . . . . . . . . . .  5
     5.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  5
   6.  AD-HOC Blocks (including 224.0.2.0/24 - 224.0.255.0/24)  . . .  5
     6.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  5
   7.  SDP/SAP Block (224.2/16) . . . . . . . . . . . . . . . . . . .  5
     7.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  5  6
   8.  Source Specific Multicast Block (232/8)  . . . . . . . . . . .  6
     8.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  6
   9.  GLOP Block (233/8) . . . . . . . . . . . . . . . . . . . . . .  6
     9.1.  Assignment Guidelines  . . . . . . . . . . . . . . . . . .  6
     9.2.  Extended AD-HOC  . . . . . . . . . . . . . . . . . . . . .  6
   10. Administratively Scoped Address Block (239/8)  . . . . . . . .  6  7
     10.1. Assignment Guidelines  . . . . . . . . . . . . . . . . . .  7
   11. Application Form . . . . . . . . . . . . . . . . . . . . . . .  7
     11.1. Size of assignments of IPv4 Multicast Addresses  . . . . .  7  8
   12. Annual Review  . . . . . . . . . . . . . . . . . . . . . . . .  8
     12.1. Address Reclamation  . . . . . . . . . . . . . . . . . . .  8
     12.2. Positive renewal . . . . . . . . . . . . . . . . . . . . .  8
   13. Use of IANA Reserved Addresses . . . . . . . . . . . . . . . .  8  9
   14. IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8  9
   15. Security Considerations  . . . . . . . . . . . . . . . . . . .  8  9
   16. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  9
   17. References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     17.1. Normative References . . . . . . . . . . . . . . . . . . .  9
     17.2. Informative References . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
   Intellectual Property and Copyright Statements . . . . . . . . . . 11 12

1.  Introduction

   The Internet Assigned Numbers Authority (IANA) (www.iana.org) is
   charged with allocating parameter values for fields in protocols
   which have been designed, created or are maintained by the Internet
   Engineering Task Force (IETF).  RFC 2780 [RFC2780] provides the IANA
   guidance in the assignment of parameters for fields in newly
   developed protocols.  This memo expands on section 4.4.2 of RFC 2780
   and attempts to codify existing IANA practice used in the assignment
   IPv4 multicast addresses.

   This document is a revision of RFC 3171 [RFC3171], which it
   obsoletes.  It should retain RFC 3171's status as BCP 51.  It also
   obsoletes RFC 3138 [RFC3138]."

   The terms "Specification Required", "Expert Review", "IESG Approval",
   "IETF Consensus", and "Standards Action", are used in this memo to
   refer to the processes described in [RFC2434].  The keywords MUST,
   MUST NOT, MAY, OPTIONAL, REQUIRED, RECOMMENDED, SHALL, SHALL NOT,
   SHOULD, SHOULD NOT are to be interpreted as defined in [RFC2119].

   In general, due to the relatively small size of the IPv4 multicast
   address space, further assignment of IPv4 multicast address space is
   recommended only in limited circumstances.  Specifically, the IANA
   should only assign addresses in those cases where the dynamic
   selection (SDP/SAP), GLOP, SSM or Administratively Scoped address
   spaces cannot be used.  The guidelines described below are reflected
   in <http://www.iana.org/numbers.html>.  Network operators should also
   be aware of the availability of IPv6 multicast addresses and consider
   using them where feasible.

2.  Terminology

   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 BCP 14, RFC 2119
   [RFC2119].

   The word "allocation" is defined as a block of addresses managed by a
   registry for the purpose of making assignments and allocations.  The
   word "assignment" is defined a block of addresses, or a single
   address, registered to an end-user for use on a specific network, or
   set of networks.

3.  Definition of Current Assignment Practice

   Unlike IPv4 unicast address assignment, where blocks of addresses are
   delegated to Regional Internet Registries (RIRs), IPv4 multicast
   addresses are assigned directly by the IANA.  Current registration
   groups appear as follows [IANA]:

224.0.0.0   - 224.0.0.255      224.0.0/24 Local Network Control Block

224.0.1.0   - 224.0.1.255      224.0.1/24 Internetwork Control Block

224.0.2.0   - 224.0.255.0      64769      AD-HOC Block (1)

224.1.0.0   - 224.1.255.255    224.1/16   RESERVED

224.2.0.0   - 224.2.255.255    224.2/16   SDP/SAP Block

224.252.0.0 - 224.255.255.255  224.252/14 RESERVED

225.0.0.0   - 231.255.255.255  7 /8s      RESERVED

232.0.0.0   - 232.255.255.255  232/8     Source Specific Multicast Block

233.0.0.0   - 233.251.255.255  16515072   GLOP Block

233.252.0.0 - 233.255.255.255  233.252/14 AD-HOC Block (2)

234.0.0.0   - 238.255.255.255  5 /8s      RESERVED

239.0.0.0   - 239.255.255.255  239/8      Administratively Scoped Block

   The IANA generally assigns addresses from the Local Network Control,
   Internetwork Control and AD-HOC blocks.  Assignment guidelines for
   each of these blocks, as well as for the Source Specific Multicast,
   GLOP and Administratively Scoped Blocks, are described below.

4.  Local Network Control Block (224.0.0/24)

   Addresses in the Local Network Control block are used for protocol
   control traffic that is not forwarded off link.  Examples of this
   type of use include OSPFIGP All Routers (224.0.0.5) [RFC2328].

4.1.  Assignment Guidelines

   Pursuant to section 4.4.2 of [RFC2780], assignments from the Local
   Network Control block follow an Expert Review, IESG Approval or
   Standards Action process.  See IANA [IANA] for the current set of
   assignments.

5.  Internetwork Control Block (224.0.1/24)

   Addresses in the Internetwork Control block are used for protocol
   control that MAY be forwarded through the Internet.  Examples include
   224.0.1.1 (NTP [RFC2030]) and 224.0.1.68 (mdhcpdiscover [RFC2730]).

5.1.  Assignment Guidelines

   Pursuant to section 4.4.2 of [RFC2780], assignments from the
   Internetwork Control block follow an Expert Review, IESG Approval or
   Standards Action process.  See IANA [IANA] for the current set of
   assignments.

6.  AD-HOC Blocks (including 224.0.2.0/24 - 224.0.255.0/24)

   Addresses in the AD-HOC blocks were traditionally used for
   assignments for those applications that don't fit in either the Local
   or Internetwork Control blocks.  These addresses are globally routed
   and are typically used by applications that require small blocks of
   addressing (e.g., less than a /24 ).  Future assignments of blocks of
   addresses that do not fit in the Local or Internetwork block will be
   made in the Extended block.

6.1.  Assignment Guidelines

   In general, the IANA SHOULD NOT assign addressing in the AD-HOC
   Block.
   Blocks.  However, the IANA MAY under special circumstances, assign
   addresses from this block. these blocks.  Pursuant to section 4.4.2 of [RFC2780],
   assignments from the AD-HOC block blocks follow an Expert Review, IESG
   Approval or Standards Action process.  See IANA [IANA] for the
   current set of assignments.

7.  SDP/SAP Block (224.2/16)

   Addresses in the SDP/SAP block are used by applications that receive
   addresses through the Session Announcement Protocol [RFC2974] for use
   via applications like the session directory tool (such as SDR [SDR]).

7.1.  Assignment Guidelines

   Since addresses in the SDP/SAP block are chosen randomly from the
   range of addresses not already in use [RFC2974], no IANA assignment
   policy is required.  Note that while no additional IANA assignment is
   required, addresses in the SDP/SAP block are explicitly for use by
   SDP/SAP and MUST NOT be used for other purposes.

8.  Source Specific Multicast Block (232/8)

   The Source Specific Multicast (SSM) is an extension of IP Multicast
   in which traffic is forwarded to receivers from only those multicast
   sources for which the receivers have explicitly expressed interest,
   and is primarily targeted at one-to-many (broadcast) applications.
   Note that this block as initially assigned to the VMTP transient
   groups IANA [IANA].

8.1.  Assignment Guidelines

   Because the SSM model essentially makes the entire multicast address
   space local to the host, no IANA assignment policy is required.
   Note, however, that while no additional IANA assignment is required,
   addresses in the SSM block are explicitly for use by SSM and MUST NOT
   be used for other purposes.

9.  GLOP Block (233/8)

   Addresses in the GLOP block are globally scoped statically assigned
   addresses.  The assignment is made, for a domain with 16 bit
   Autonomous System Number (ASN), by mapping a domain's autonomous the
   system number, expressed in octets as X.Y, system number into the middle two octets
   of of the GLOP block, yielding an assignment of 233.X.Y.0/24.  The
   mapping and assignment is defined in [RFC3180].  Domains with 32 bit
   ASN should apply for space in the Extended AD-HOC block. block, or consider
   using IPv6 multicast addresses.

9.1.  Assignment Guidelines

   Because addresses in the GLOP block are algorithmically pre-assigned,
   no IANA assignment policy is required.

9.2.  Extended AD-HOC

   [RFC3138] delegated assignment of the GLOP sub-block mapped by the
   [RFC1930] private AS space (233.252.0.0 - 233.255.255.255) to the
   RIRs.  This space was known as eGLOP.  The RIRs did  RFC 3138 should not have asked
   the RIRs to develop policies or the mechanisms for the assignment of the eGLOP EGLOP space and
   it because [RFC2860]
   reserves that to the IETF.  It is important to make this space
   available for use by network
   operators.  It operators and it is therefore
   appropriate to obsolete RFC 3138 and classify this address range as
   available for AD-HOC assignment as per the guidelines in section 6.

   The first /24 in this range, 233.252.0.0/24, is assigned as "MCAST-
   TEST-NET" for use in documentation and example code.  It SHOULD be
   used in conjunction with the [RFC2606] domain names example.com or
   example.net in vendor and protocol documentation.  Addresses within
   this block MUST NOT appear on the public Internet.

10.  Administratively Scoped Address Block (239/8)

   Addresses in the Administratively Scoped Address block are for local
   use within a domain and are described in [RFC2365].

10.1.  Assignment Guidelines

   Since addresses in this block are local to a domain, no IANA
   assignment policy is required.

10.1.1.  Relative Offsets

   The relative offsets [RFC2365] are used to ensure that a service can
   be located independent of the extent of the enclosing scope (see
   [RFC3180] for details).  Since there are only 256 such offsets, the
   IANA should only assign a relative offset to a protocol that provides
   an infrastructure supporting service.  Examples of such services
   include the Session Announcement Protocol [RFC2974].  Pursuant to
   section 4.4.2 of [RFC2780], assignments of Relative Offsets follow an
   Expert Review, IESG Approval or Standards Action process.  See IANA
   [IANA] for the current set of assignments.

11.  Application Form

   Requests for multicast address assignments can be submitted through
   the application form on the IANA web site at:

   <http://www.iana.org/cgi-bin/multicast.pl>

   It is important to submit sufficient detail to allow the IESG
   designated expert to review the application.  If the details given in
   the request are not clear, or further information is needed, the IESG
   designated expert may request additional information before assigning
   an address.

11.1.  Size of assignments of IPv4 Multicast Addresses

   Occasionally, more than one multicast address is required.  In these
   cases multiple addresses are available in the Extended AD-HOC block.
   Where a very large number of addresses is required, the assignment
   will be staged, with additional stages only being made after the
   complete use of the initial assignment(s).

   A separate document describing the policy governing assignment of
   addresses in the AD-HOC and Extended AD-HOC blocks will be developed
   and published.  The format, location and content has not yet been
   decided and so these will be documented in a future version of this
   document.

12.  Annual Review

   Given the dynamic nature of IPv4 multicast and its associated infra-
   structure, and the previously undocumented IPv4 multicast address
   assignment guidelines, the IANA should conduct an annual review of
   currently assigned addresses.

12.1.  Address Reclamation

   During the review described above, addresses that were mis-assigned
   should, where possible, be reclaimed or reassigned.

   The IANA should also review assignments in the AD-HOC, DIS Transient
   Groups, and ST Multicast Groups [RFC1190] blocks and reclaim those
   addresses that are not in use on the global Internet (i.e, those
   applications which can use SSM, GLOP, or Administratively Scoped
   addressing, or are not globally routed).

12.2.  Positive renewal

   It is occasionally appropriate to make temporary assignments that can
   be renewed as necessary.  In cases where this happens the registrant
   needs to positively request an extension to the temporary assignment
   or the addresses assigned.  When the IANA has not received a request
   to renew the registration of a temporary assignment within 30 days of
   the expiry of the assignment it MUST be removed from the multicast
   registry.

   Addresses returned to the IANA when a temporary assignment ends MUST
   NOT be assigned for at least one calendar year.

13.  Use of IANA Reserved Addresses

   Applications MUST NOT use addressing in the IANA reserved blocks.

14.  IANA Considerations

   This document is all about IANA Considerations.

15.  Security Considerations

   The assignment guidelines described in this document do not alter the
   security properties of either the Any Source or Source Specific
   multicast service models.

16.  Acknowledgments

   The authors would like to thank Joe St. Sauver, John Meylor, Randy
   Bush, Thomas Narten, Marshall Eubanks, Zaid Albanna (co-author of
   RFC3171), Kevin Almeroth (co-author of RFC3171) and Leo Vegoda for
   their constructive feedback and comments.

17.  References

17.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

17.2.  Informative References

   [IANA]     IANA, "IANA Matrix for Protocol Parameter Assignment/
              Registration Procedures",
              <http://www.iana.org/numbers.html>.

   [RFC1190]  Casner, S., Lynn, C., Park, P., Schroder, K., and C.
              Topolcic, "Experimental Internet Stream Protocol: Version
              2 (ST-II)", RFC 1190, October 1990.

   [RFC1930]  Hawkinson, J. and T. Bates, "Guidelines for creation,
              selection, and registration of an Autonomous System (AS)",
              BCP 6, RFC 1930, March 1996.

   [RFC2030]  Mills, D., "Simple Network Time Protocol (SNTP) Version 4
              for IPv4, IPv6 and OSI", RFC 2030, October 1996.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2365]  Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
              RFC 2365, July 1998.

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC2606]  Eastlake, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, June 1999.

   [RFC2730]  Hanna, S., Patel, B., and M. Shah, "Multicast Address
              Dynamic Client Allocation Protocol (MADCAP)", RFC 2730,
              December 1999.

   [RFC2780]  Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
              Values In the Internet Protocol and Related Headers",
              BCP 37, RFC 2780, March 2000.

   [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
              Understanding Concerning the Technical Work of the
              Internet Assigned Numbers Authority", RFC 2860, June 2000.

   [RFC2974]  Handley, M., Perkins, C., and E. Whelan, "Session
              Announcement Protocol", RFC 2974, October 2000.

   [RFC3138]  Meyer, D., "Extended Assignments in 233/8", RFC 3138,
              June 2001.

   [RFC3171]  Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper,
              "IANA Guidelines for IPv4 Multicast Address Assignments",
              BCP 51, RFC 3171, August 2001.

   [RFC3180]  Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",
              BCP 53, RFC 3180, September 2001.

Authors' Addresses

   Michelle Cotton
   Internet Corporation for Assigned Names and Numbers
   4676 Admiralty Way, Suite 330
   Marina del Rey  90292
   United States

   Phone: +310-823-9358
   Email: michelle.cotton@icann.org
   URI:   http://www.iana.org/

   David Meyer

   Email: dmm@1-4-5.net

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