Network Working Group M. Cotton
Internet-Draft ICANN
Intended status: BCP D. Meyer
Expires: May 7, 2009 November 3, 2008
IANA Guidelines for IPv4 Multicast Address Assignments
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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definition of Current Assignment Practice . . . . . . . . . . 4
4. Local Network Control Block (224.0.0/24) . . . . . . . . . . . 4
4.1. Assignment Guidelines . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . 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) . . . . . . . . 7
10.1. Assignment Guidelines . . . . . . . . . . . . . . . . . . 7
11. Application Form . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Size of assignments of IPv4 Multicast Addresses . . . . . 8
12. Annual Review . . . . . . . . . . . . . . . . . . . . . . . . 8
12.1. Address Reclamation . . . . . . . . . . . . . . . . . . . 8
12.2. Positive renewal . . . . . . . . . . . . . . . . . . . . . 8
13. Use of IANA Reserved Addresses . . . . . . . . . . . . . . . . 9
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
15. Security Considerations . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . 12
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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.
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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].
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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
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 [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]).
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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
system number, expressed in octets as X.Y, 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, 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. RFC 3138 should not have asked
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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.
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.
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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.
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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.
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[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.
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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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