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 (C) 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., [RFC2365]).  The IANA has allocated 223/8 as per RFC
  2770 [RFC2770].  This document obsoletes RFC 2770.

2. Problem Statement

  Multicast addresses have traditionally been allocated by a dynamic
  mechanism such as SDR [RFC2974].  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 [RFC2974].  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.








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  The MALLOC working group has created a specific strategy for global
  multicast address allocation [RFC2730, RFC2909].  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 [RFC2770].  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 [RFC1930] is
  assigned to the IRRs [RFC3138].

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.




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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

  [RFC1797] IANA, "Class A Subnet Experiment", RFC 1797, April 1995.

  [RFC1930] Hawkinson, J. and T. Bates,  "Guidelines for creation,
            selection, and registration of an Autonomous System (AS)",
            RFC 1930, March 1996.

  [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", RFC
            2365, July 1998.

  [RFC2374] Hinden, R., O'Dell, M. and S. Deering, "An IPv6
            Aggregatable Global Unicast Address Format", RFC 2374, July
            1998.

  [RFC2730] Hanna, S.,  Patel, B. and M. Shah, "Multicast Address
            Dynamic Client Allocation Protocol (MADCAP)", RFC 2730,
            December 1999.

  [RFC2770] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8", RFC
            2770, February 2000.

  [RFC2909] Radoslavov, P., Estrin, D., Govindan, R., Handley, M.,
            Kumar, S. and D. Thaler, "The Multicast Address-Set Claim
            (MASC) Protocol", RFC 2909, September 2000.





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  [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.

10. Authors' Addresses

  David Meyer
  Sprint
  VARESA0104
  12502 Sunrise Valley Drive
  Reston VA, 20196

  EMail: [email protected]


  Peter Lothberg
  Sprint
  VARESA0104
  12502 Sunrise Valley Drive
  Reston VA, 20196

  EMail: [email protected]



























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11. 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.

Acknowledgement

  Funding for the RFC Editor function is currently provided by the
  Internet Society.



















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