GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:bcp:bcp51

Internet Engineering Task Force (IETF) M. Cotton Request for Comments: 5771 L. Vegoda BCP: 51 ICANN Updates: 2780 D. Meyer Obsoletes: 3138, 3171 March 2010 Category: Best Current Practice ISSN: 2070-1721

       IANA Guidelines for IPv4 Multicast Address Assignments

Abstract

 This document provides guidance for the Internet Assigned Numbers
 Authority (IANA) in assigning IPv4 multicast addresses.  It obsoletes
 RFC 3171 and RFC 3138 and updates RFC 2780.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 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
 BCPs is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc5771.

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 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.

Cotton, et al. Best Current Practice [Page 1] RFC 5771 IPv4 Multicast Guidelines March 2010

Table of Contents

 1. Introduction ....................................................2
 2. Terminology .....................................................3
 3. Definition of Current Assignment Practice .......................3
 4. Local Network Control Block (224.0.0/24) ........................4
    4.1. Assignment Guidelines ......................................4
 5. Internetwork Control Block (224.0.1/24) .........................5
    5.1. Assignment Guidelines ......................................5
 6. AD-HOC Blocks (I, II, and III) ..................................5
    6.1. Assignment Guidelines ......................................5
 7. SDP/SAP Block (224.2/16) ........................................5
    7.1. Assignment Guidelines ......................................5
 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. AD-HOC Block III ...........................................6
 10. Administratively Scoped Block (239/8) ..........................7
    10.1. Assignment Guidelines .....................................7
         10.1.1. Relative Offsets ...................................7
 11. Application Form ...............................................7
    11.1. Size of Assignments of IPv4 Multicast Addresses ...........7
 12. Annual Review ..................................................8
    12.1. Address Reclamation .......................................8
    12.2. Positive Renewal ..........................................8
 13. Use of IANA Reserved Addresses .................................8
 14. IANA Considerations ............................................8
 15. Security Considerations ........................................9
 16. Acknowledgments ................................................9
 17. References .....................................................9
    17.1. Normative References ......................................9
    17.2. Informative References ....................................9

1. Introduction

 The Internet Assigned Numbers Authority (IANA) (www.iana.org) is
 charged with allocating parameter values for fields in protocols that
 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
 of IPv4 multicast addresses.

Cotton, et al. Best Current Practice [Page 2] RFC 5771 IPv4 Multicast Guidelines March 2010

 This document is a revision of RFC 3171 [RFC3171], which it
 obsoletes.  It also obsoletes RFC 3138 [RFC3138] and updates
 [RFC2780].
 The terms "Specification Required", "Expert Review", "IESG Approval",
 "IETF Review", and "Standards Action", are used in this memo to refer
 to the processes described in [RFC5226].
 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:
  1. the dynamic selection Session Description Protocol/Session

Announcement Protocol (SDP/SAP);

  1. GLOP (not an acronym);
  1. Source-Specific Multicast (SSM); or
  1. Administratively Scoped address spaces cannot be used.
 The guidelines described below are reflected in [IANA-protocols].
 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" designates a block of addresses managed by a
 registry for the purpose of making assignments and allocations.  The
 word "assignment" designates 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]:

Cotton, et al. Best Current Practice [Page 3] RFC 5771 IPv4 Multicast Guidelines March 2010

Address Range Size Designation ————- —- ———– 224.0.0.0 - 224.0.0.255 (/24) Local Network Control Block

224.0.1.0 - 224.0.1.255 (/24) Internetwork Control Block

224.0.2.0 - 224.0.255.255 (65024) AD-HOC Block I

224.1.0.0 - 224.1.255.255 (/16) RESERVED

224.2.0.0 - 224.2.255.255 (/16) SDP/SAP Block

224.3.0.0 - 224.4.255.255 (2 /16s) AD-HOC Block II

224.5.0.0 - 224.255.255.255 (251 /16s) RESERVED

225.0.0.0 - 231.255.255.255 (7 /8s) RESERVED

232.0.0.0 - 232.255.255.255 (/8) Source-Specific Multicast Block

233.0.0.0 - 233.251.255.255 (16515072) GLOP Block

233.252.0.0 - 233.255.255.255 (/14) AD-HOC Block III

234.0.0.0 - 238.255.255.255 (5 /8s) RESERVED

239.0.0.0 - 239.255.255.255 (/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.

Cotton, et al. Best Current Practice [Page 4] RFC 5771 IPv4 Multicast Guidelines March 2010

5. Internetwork Control Block (224.0.1/24)

 Addresses in the Internetwork Control Block are used for protocol
 control traffic that MAY be forwarded through the Internet.  Examples
 include 224.0.1.1 (Network Time Protocol (NTP) [RFC4330]) 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 (I, II, and III)

 Addresses in the AD-HOC blocks (including 224.0.2.0 - 224.0.255.255,
 224.3.0.0 - 224.4.255.255, and 233.252.0.0 - 233.255.255.255) were
 traditionally used for assignments for those applications that don't
 fit in either the Local or Internetwork Control blocks.  These
 addresses MAY be 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 Network or Internetwork Control blocks will be made in
 AD-HOC Block III.

6.1. Assignment Guidelines

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

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.

Cotton, et al. Best Current Practice [Page 5] RFC 5771 IPv4 Multicast Guidelines March 2010

8. Source-Specific Multicast Block (232/8)

 SSM [RFC4607] 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 was initially assigned to the Versatile Message Transaction
 Protocol (VMTP) transient groups [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 Source-Specific Multicast 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 a 16-bit
 Autonomous System Number (ASN), by mapping a domain's autonomous
 system number, expressed in octets as X.Y, into the middle two octets
 of the GLOP Block, yielding an assignment of 233.X.Y.0/24.  The
 mapping and assignment is defined in [RFC3180].  Domains with a
 32-bit ASN MAY apply for space in AD-HOC Block III, 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. AD-HOC Block III

 [RFC3138] delegated to the RIRs the assignment of the GLOP sub-block
 (233.252.0.0 - 233.255.255.255) mapped by the private Autonomous
 System (AS) space (64512-65534) and the IANA reserved ASN 65535
 [RFC1930].  This space was known as Extended GLOP (EGLOP).  RFC 3138
 should not have asked the RIRs to develop policies for the EGLOP
 space because [RFC2860] reserves that to the IETF.  It is important
 to make this space available for use by network 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.

Cotton, et al. Best Current Practice [Page 6] RFC 5771 IPv4 Multicast Guidelines March 2010

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

10. Administratively Scoped Block (239/8)

 Addresses in the Administratively Scoped 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] 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 [IANA-registration].  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 AD-HOC Block III.  Where
 there is a requirement for a very large number of addresses, the
 assignment will be staged.  The additional stages will only be made
 after the complete use of the initial assignment(s).

Cotton, et al. Best Current Practice [Page 7] RFC 5771 IPv4 Multicast Guidelines March 2010

 A separate document describing the policy governing assignment of
 addresses in the AD-HOC blocks I, II, and III 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
 infrastructure, 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 [RFC1819] blocks and reclaim those
 addresses that are not in use on the global Internet (i.e., those
 applications that 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 to anyone other than the last registrant 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

 IANA has updated its IPv4 multicast request and assignment procedures
 to reflect this document.

Cotton, et al. Best Current Practice [Page 8] RFC 5771 IPv4 Multicast Guidelines March 2010

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 RFC
 3171), Kevin Almeroth (co-author of RFC 3171), Pekka Savola, and
 Alfred Hoenes 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.
 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
           IANA Considerations Section in RFCs", BCP 26, RFC 5226, May
           2008.

17.2. Informative References

 [IANA]    IANA, "IANA Protocol Registries", <http://www.iana.org/>.
 [IANA-protocols]
           IANA, "IANA Protocol Registries",
           <http://www.iana.org/protocols>.
 [IANA-registration]
           IANA, "IANA Protocol Registration Forms",
           <http://www.iana.org/protocols/apply>.
 [RFC1819] Delgrossi, L., Ed., and L. Berger, Ed., "Internet Stream
           Protocol Version 2 (ST2) Protocol Specification - Version
           ST2+", RFC 1819, August 1995.
 [RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,
           selection, and registration of an Autonomous System (AS)",
           BCP 6, RFC 1930, March 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.

Cotton, et al. Best Current Practice [Page 9] RFC 5771 IPv4 Multicast Guidelines March 2010

 [RFC2606] Eastlake 3rd, 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.
 [RFC4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4
           for IPv4, IPv6 and OSI", RFC 4330, January 2006.
 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
           IP", RFC 4607, August 2006.
 [SDR]     University College London / ISI, "Session Directory Tool",
           <http://www-mice.cs.ucl.ac.uk/multimedia/software/sdr/>.

Cotton, et al. Best Current Practice [Page 10] RFC 5771 IPv4 Multicast Guidelines March 2010

Authors' Addresses

 Michelle Cotton
 Internet Corporation for Assigned Names and Numbers
 4676 Admiralty Way, Suite 330
 Marina del Rey, CA 90292
 United States of America
 Phone: +310-823-9358
 EMail: michelle.cotton@icann.org
 URI:   http://www.iana.org/
 Leo Vegoda
 Internet Corporation for Assigned Names and Numbers
 4676 Admiralty Way, Suite 330
 Marina del Rey, CA 90292
 United States of America
 Phone: +310-823-9358
 EMail: leo.vegoda@icann.org
 URI:   http://www.iana.org/
 David Meyer
 EMail: dmm@1-4-5.net

Cotton, et al. Best Current Practice [Page 11]

/data/webs/external/dokuwiki/data/pages/rfc/bcp/bcp51.txt · Last modified: 2010/03/15 20:17 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki