Network Working Group Zaid Albanna INTERNET DRAFT
WorldcomJuniper Networks Kevin Almeroth UCSB David Meyer Cisco Systems Michelle Schipper IANA Category Best Current Practices March,April, 2001 IANA Guidelines for IPv4 Multicast Address Allocation <draft-ietf-mboned-iana-ipv4-mcast-guidelines-00.txt><draft-ietf-mboned-iana-ipv4-mcast-guidelines-01.txt> 1. Status of this Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 2. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. 3. Abstract This memo provides guidance for the IANA in assigning IPv4 multicast addresses. 4. 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. 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 RFC 2119 [RFC2119]. In general, due to the relatively small size of the IPv4 multicast addresses space, further allocation of IPv4 multicast address space is not recommended. 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. 5. Definition of Current Assignment Practice Unlike IPv4 unicast address assignment, where blocks of addresses are delegated to regional registries, IPv4 multicast addresses are assigned directly by the IANA. Current allocations appear as follows [IANA]: 126.96.36.199 - 188.8.131.52 (224.0.0/24) Local Network Control Block 184.108.40.206 - 220.127.116.11 (224.0.1/24) Internetwork Control Block 18.104.22.168 - 22.214.171.124 AD-HOC Block 126.96.36.199 - 188.8.131.52 (224.1/16) ST Multicast Groups 184.108.40.206 - 220.127.116.11 (224.2/16) SDP/SAP Block 18.104.22.168 - 22.214.171.124 DIS Transient Block 126.96.36.199 - 188.8.131.52 (225/8) MALLOC Block 184.108.40.206 - 220.127.116.11 RESERVED 18.104.22.168 - 22.214.171.124 (232/8) Source Specific Multicast Block 126.96.36.199 - 188.8.131.52 (233/8) GLOP Block 184.108.40.206 - 220.127.116.11 RESERVED 18.104.22.168 - 22.214.171.124 (239/8) Administratively Scoped Block The IANA generally allocates addresses from the Local Network Control, Internetwork Control, and AD-HOC blocks. Allocation guidelines for each of these blocks, as well as for the MALLOC, Source Specific Multicast, GLOP and Administratively Scoped Blocks, are described below. Note that while some applications may informally use arbitrary parts of the IPv4 multicast address space (e.g., 229/8), an application MUST NOT use address space that is not allocated as described in this memo. 6. 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 (126.96.36.199) [RFC2328]. 6.1. Allocation Guidelines Allocation of addresses in the Local Network Configuration Block SHOULD BE be accompanied by a specification ("Specification Required"). This specification will typically take the form of an internet draft or RFC. Internet Draf-draft-ietf-mboned-iana-IPv4-mcast-guidelines-01.txt April, 2001 7. Internetwork Control Block (224.0.1/24) Addresses in the Internetwork Control block are used for protocol control that must be forwarded through the Internet. Examples include 188.8.131.52 (NTP [RFC2030]) and 184.108.40.206 (mdhcpdisover [RFC2730]). 7.1. Allocation Guidelines Allocation of addresses in the Internetwork Control block SHOULD BE accompanied by a specification ("Specification Required"). This specification will typically take the form of an internet draft or RFC. 8. AD-HOC Block (220.127.116.11/24 - 18.104.22.168/24) Addresses in the AD-HOC block have traditionally been allocated 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). 8.1. Allocation Guidelines Allocation of addresses in the AD-HOC Block SHOULD BE accompanied by a specification ("Specification Required").This specification will typically take the form of an internet draft or RFC. In general, the IANA SHOULD NOT assign addressing in the AD-HOC Block. 9. 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]). 9.1. Allocation Guidelines Since addresses in the SDP/SAP block are chosen randomly from the range of addresses not already in use [RFC2974], no IANA allocation policy is required. Note that while no additional IANA allocation is required, addresses in the SDP/SAP block are explicitly for use by SDP/SAP and MUST NOT be used for other purposes. 10. MALLOC Block (225/8) Addresses in the MALLOC block are dynamically allocated by the MALLOC suite of protocols [RFC2908]. This assignment is temporary and MUST BE reviewed annually. 10.1. Allocation Guidelines Since addresses in the MALLOC block are chosen by elements of the MALLOC architecture, no IANA allocation policy is required. Note that while no additional IANA allocation is required, addresses in the MALLOC block are explicitly for allocation by MALLOC servers and MUST NOT be used for other purposes. 11. Source Specific Multicast Block (232/8) The Source Specific Multicast (SSM) block use is outlined in [SSM]. In general, SSMis 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 where large receiver audiences require traffic from a small number of well known sources.applications. 11.1. Allocation Guidelines Because the SSM model essentially makes the entire multicast address space local to the host, no IANA allocation policy is required. Note, however, that while no additional IANA allocation is required, addresses in the SSM block are explicitly for use by SSM and MUST NOT be used for other purposes. 12. GLOP Block (233/8) Addresses in the GLOP block are globally scoped statically assigned addresses. The assignment is made by mapping a domain's autonomous system number into the middle two octets of 233.X.Y.0/24. The mapping and allocation is defined in [RFC2770]. 12.1. Allocation Guidelines Because addresses in the GLOP block are algorithmically preassigned, no IANA allocation policy is required. Note that while no additional IANA allocation is required, addresses in the GLOP block are allocated for use as defined in RFC 2770 and MUST NOT be used for other purposes. 13. 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]. 13.1. Allocation Guidelines Since addresses in this block are local to a domain, no IANA allocation policy is required. 13.1.1. 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 RFC 2770 for details). Since there are only 256 such offsets, the IANA should only assign a relative offset to a protocol that provides an infra- structureinfra-structure supporting service. Examples of such services include the Session Announcement Protocol [RFC2974]. See [IANA] for the current set of assignments. 14. 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. 14.1. Address Reclamation During the review described above, addresses that were mis-assigned should, where possible, be reclaimed or reassigned. An example of an address block that might be reclaimed is 224.1.0/24 [RFC1190], as this was an experimental allocation and is not in use. In addition, those allocations in 224.0.1/24 that are not used for Internet-wide protocol control messages (as described above) above might be reclaimed. The IANA should also review assignments in the AD-HOC, DIS Transient Groups, and ST Multicast Groups 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). 15. Use of IANA Reserved Addresses Applications MUST NOT use addressing in the IANA reserved blocks. 16. Appeals Process An applicant that is denied a multicast assignment may ask for additional consideration of its application. Such appeals SHOULD be granted only in those cases in which (i). the applicant did not provide a specification, or (ii). the applicant believes that the IANA did not understand the technical basis on which the application rests (and hence the need for assignmentAppleals of globally scoped addressing). 16.1. Requirements [RFC2026] All appeals must include a detailed and specific description of the facts of the dispute. All appeals must be initiated within two months of the public knowledge of the action or decision to be challenged. At all stages of the appeals process, the individuals or bodies responsible for making the decisions have the discretion to define the specific procedures they will follow in thethis process of making their decision. In all cases a decision concerning the disposition of the dispute, and the communication of that decision to the parties involved, must be accomplished within a reasonable period of time. 16.2. Process When an application is appealed, the application (and specification, if one was provided) is to be reviewed by the IESG, indicatingare to the IANA whether the application shouldbe accepted. The IESG MAY additionally employ Expert Review of the application. 16.2.1. Process Failure If an applicant should disagree with an action taken by the IANA and IESGhandled in this process, that application should first try to clairfy its positionaccordance with the IANA. If the IANA is unable to satisfy the applicant, the applicant may ask for its application (and specification, if one was provided) to be reviewed by the IAB. The IAB decision is final with respect to the questionSection 6.5 of whether an assignment should be made.RFC 2026 [RFC2026]. 17. Security Considerations Security issues are not discussedThe allocation guidelines described in this memo.document do not alter the security properties of either the Any Source or Source Specific multicast service models. 18. Acknowledgments The authors would like to thank Joe St. Sauver andSauver, John MeylorMeylor, and Randy Bush for their constructive feedback and comments. 19. Author's Address: Zaid Albanna Worldcom 22001 Loudoun County Parkway Ashburn, VA. 20147 Email: email@example.com N. Mathilda Ave Sunnyvale, CA. 94089 firstname.lastname@example.org Kevin Almeroth UC Santa Barbara Sata Barbara, CA. Email: email@example.com David Meyer Cisco Systems, Inc. 170 Tasman Drive San Jose, CA, 95134 Email: firstname.lastname@example.org Michelle Schipper IANA Administrator email@example.com 20. References [IANA] http://www.iana.org [RFC1190] C. Topolcic, "Experimental Internet Stream Protocol, Version 2 (ST-II)", RFC 1190, October, 1990. [RFC2026] S. Bradner, "The Internet Standards Process -- Revision 3", RFC2026, October 1996. [RFC2030] Mills, D., Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI", D. Mills, October 1996. [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March, 1997. [RFC2328] J. Moy,"OSPF Version 2", RFC 2328, April, 1998. [RFC2365] D. Meyer,"Administratively Scoped IP Multicast", 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. [RFC2730] Hanna, S., Patel, B. and M. Shah, "Multicast Address Dynamic Client Allocation Protocol (MADCAP), December 1999. [RFC2770] D. Meyer, and P. Lothberg, "GLOP Addressing in 233/8", RFC 2770, February, 2000 [RFC2780] S. Bradner and V. Paxson, "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers", RFC2780, March, 2000 [RFC2908] D. Thaler, M. Handley, D.Estrin, "The"Theh Internet Multicast Address Allocation Architecture", RFC 2908, September 2000. [RFC2974] M. Handley, C. Perkins, E. Whelan, "Session Announcement Protocol", RFC 2974, October 2000. [SDR] http://www.aciri.org/sdr/ [SSM] Holbrook, H., and Cain, B., "Source-Specific Multicast for IP", draft-holbrook-ssm-arch-01.txt, Work in progress.21. Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.