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IETF RFC 3180

GLOP Addressing in 233/8

Last modified on Monday, September 17th, 2001

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Network Working Group                                           D. Meyer
Request for Comments: 3180                                   P. Lothberg
Obsoletes: 2770                                                   Sprint
BCP: 53                                                   September 2001
Category: Best Current Practice 


                        GLOP Addressing in 233/8

 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.

 Copyright Notice

   Copyright © The Internet Society (2001).  All Rights Reserved.

 Abstract

   This document defines the policy for the use of 233/8 for statically
   assigned multicast addresses.

1. Introduction

   It is envisioned that the primary use of this space will be many-to-
   many applications.  This allocation is in addition to those described
   on [IANA] (e.g., [RFC 2365]).  The IANA has allocated 223/8 as per RFC
   2770 [RFC 2770].  This document obsoletes RFC 2770.

2. Problem Statement

   Multicast addresses have traditionally been allocated by a dynamic
   mechanism such as SDR [RFC 2974].  However, many current multicast
   deployment models are not amenable to dynamic allocation.  For
   example, many content aggregators require group addresses that are
   fixed on a time scale that is not amenable to allocation by a
   mechanism such as described in [RFC 2974].  Perhaps more seriously,
   since there is not general consensus by providers, content
   aggregators, or application writers as to the allocation mechanism,
   the Internet is left without a coherent multicast address allocation
   scheme.








Meyer & Lothberg         Best Current Practice               PAGE 1 top


RFC 3180 GLOP Addressing in 233/8 September 2001 The MALLOC working group has created a specific strategy for global multicast address allocation [RFC 2730, RFC 2909]. However, this approach has not been widely implemented or deployed. This document proposes a solution for a subset of the problem, namely, those cases not covered by Source Specific Multicast. 3. Address Space The IANA has allocated 223/8 as per RFC 2770 [RFC 2770]. RFC 2770 describes the administration of the middle two octets of 233/8 in a manner similar to that described in RFC 1797: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 233 | 16 bits AS | local bits | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.1. Example Consider, for example, AS 5662. Written in binary, left padded with 0s, we get 0001011000011110. Mapping the high order octet to the second octet of the address, and the low order octet to the third octet, we get 233.22.30/24. 4. Allocation As mentioned above, the allocation proposed here follows the RFC 1797 (case 1) allocation scheme, modified as follows: the high-order octet has the value 233, and the next 16 bits are a previously assigned Autonomous System number (AS), as registered by a network registry and listed in the RWhois database system. This allows a single /24 per AS. As was the case with RFC 1797, using the AS number in this way allows automatic assignment of a single /24 to each service provider and does not require an additional registration step. 4.1. Private AS Space The part of 233/8 that is mapped to the private AS space [RFC 1930] is assigned to the IRRs [RFC 3138]. 5. Large AS Numbers It is important to note that this approach will work only for two octet AS numbers. In particular, it does not work for any AS number extension scheme. Meyer & Lothberg Best Current Practice PAGE 2 top

RFC 3180 GLOP Addressing in 233/8 September 2001 6. Security Considerations The approach described here may have the effect of reduced exposure to denial-of-service attacks based on dynamic allocation. Further, since dynamic assignment does not cross domain boundaries, well-known intra-domain security techniques can be applied. 7. IANA Considerations The IANA has assigned 233/8 for this purpose. 8. Acknowledgments This proposal originated with Peter Lothberg's idea that we use the same allocation (AS based) as described in RFC 1797. Randy Bush and Mark Handley contributed many insightful comments, and Pete and Natalie Whiting contributed greatly to the readability of this document. 9. References [IANA] http://www.iana.org/numbers.html [RFC 1797] IANA, "Class A Subnet Experiment", RFC 1797, April 1995. [RFC 1930] Hawkinson, J. and T. Bates, "Guidelines for creation, selection, and registration of an Autonomous System (AS)", RFC 1930, March 1996. [RFC 2365] Meyer, D., "Administratively Scoped IP Multicast", RFC 2365, July 1998. [RFC 2374] Hinden, R., O'Dell, M. and S. Deering, "An IPv6 Aggregatable Global Unicast Address Format", RFC 2374, July 1998. [RFC 2730] Hanna, S., Patel, B. and M. Shah, "Multicast Address Dynamic Client Allocation Protocol (MADCAP)", RFC 2730, December 1999. [RFC 2770] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8", RFC 2770, February 2000. [RFC 2909] Radoslavov, P., Estrin, D., Govindan, R., Handley, M., Kumar, S. and D. Thaler, "The Multicast Address-Set Claim (MASC) Protocol", RFC 2909, September 2000. Meyer & Lothberg Best Current Practice PAGE 3 top

RFC 3180 GLOP Addressing in 233/8 September 2001 [RFC 2974] Handley, M., Perkins, C. and E. Whelan, "Session Announcement Protocol", RFC 2974, October 2000. [RFC 3138] Meyer, D., "Extended Assignments in 233/8", RFC 3138, June 2001. 10. Authors' Addresses David Meyer Sprint VARESA0104 12502 Sunrise Valley Drive Reston VA, 20196 EMail: dmm@sprint.net Peter Lothberg Sprint VARESA0104 12502 Sunrise Valley Drive Reston VA, 20196 EMail: roll@sprint.net Meyer & Lothberg Best Current Practice PAGE 4 top

RFC 3180 GLOP Addressing in 233/8 September 2001 11. Full Copyright Statement Copyright © 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Meyer & Lothberg Best Current Practice PAGE 5 top

GLOP Addressing in 233/8 RFC TOTAL SIZE: 8225 bytes PUBLICATION DATE: Monday, September 17th, 2001 LEGAL RIGHTS: The IETF Trust (see BCP 78)


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