IANA Guidelines for IPv4 Multicast Address Assignments
RFC 5771
also known as BCP 51
Document | Type |
RFC
- Best Current Practice
(March 2010)
Errata
Updates RFC 2780
|
|
---|---|---|---|
Authors | David Meyer , Michelle Cotton , Leo Vegoda | ||
Last updated | 2013-03-02 | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Additional resources | Mailing list discussion | ||
IESG | Responsible AD | Ron Bonica | |
Send notices to | (None) |
RFC 5771
#x27;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]