GLOP Addressing in 233/8

Network Working Group                                         D. Meyer
Request for Comments: 2770                               Cisco Systems
Category: Experimental                                     P. Lothberg
                                                                Sprint
                                                         February 2000


                        GLOP Addressing in 233/8

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This describes an experimental policy for use of the class D address
   space using 233/8 as the experimental statically assigned subset of
   the class D address space. This new experimental allocation is in
   addition to those described on [IANA] (e.g. [RFC2365]).

   This memo is a product of the Multicast Deployment Working Group
   (MBONED) in the Operations and Management Area of the Internet
   Engineering Task Force. Submit comments to <mboned@ns.uoregon.edu> or
   the authors.

1. Problem Statement

   Multicast addresses have traditionally been allocated by a dynamic
   mechanism such as SDR [SAP]. However, many current multicast
   deployment models are not amenable to dynamic allocation. For
   example, many content aggregators require group addresses which are
   fixed on a time scale which is not amenable to allocation by a
   mechanism such as described in [SAP]. Perhaps more seriously, since
   there isn't 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.

   The MALLOC working group is looking at a specific strategy for global
   multicast address allocation [MADCAP, MASC]. This experiment will
   proceed in parallel. MADCAP may be employed within AS's, if so
   desired.

   This document proposes an experimental method of statically
   allocating multicast addresses with global scope. This experiment
   will last for a period of one year, but may be extended as described
   in section 6.

2. Address Space

   For purposes of the experiment described here, the IANA has allocated
   233/8. The remaining 24 bits will be administered 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   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

2.1. 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.

3. 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
   the experiment to get underway quickly in that it automatically
   allocates some addresses to each service provider and does not
   require a registration step.

3.1. Private AS Space

   The address space mapped to the private AS space [RFC1930] is
   reserved for future allocation.

4. Transition from GLOP to Other Address Allocation Schemes

   It may not be necessary to transition from the address allocation
   scheme described here to a more dynamic approach (see, e.g., [MASC]).
   The reasoning here is that the statically assigned addresses taken
   from 233/8 may be sufficient for those applications which must have
   static addressing, and any other addressing can come from either a
   dynamic mechanism such as [MASC], the administratively scoped address
   space [RFC2365], or the Single-source address space [SS].

5. Security Considerations

   The approach described here may have the effect of reduced exposure
   to denial of space attacks based on dynamic allocation. Further,
   since dynamic assignment does not cross domain boundaries, well known
   intra-domain security techniques can be applied.

6. IANA Considerations

   IANA has allocated 233/8 for experimental assignments. This
   assignment should timeout one year after the assignment is made. The
   assignment may be renewed at that time. It should be noted that the
   experiment described here is in the same spirit the experiment
   described in [RFC1797].

7. Acknowledgments

   This idea originated with Peter Lothberg's idea that we use the same
   allocation (AS based) as described in RFC 1797 in the class D address
   space. Randy Bush and Mark Handley contributed many insightful
   comments.

8. References

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

   [MASC]    D. Estrin, et al., "The Multicast Address-Set Claim (MASC)
             Protocol", Work in Progress.

   [MSDP]    D. Farinacci et al., "Multicast Source Discovery Protocol
             (MSDP)", Work in Progress.

   [IANA]    www.isi.edu/in-notes/iana/assignments/multicast-addresses
   [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.

   [SAP]     Handley, M., "SAP: Session Announcement Protocol", Work in
             Progress.

   [SS]      www.isi.edu/in-notes/iana/assignments/single-source-
             multicast

9. Authors' Addresses

   David Meyer
   Cisco Systems, Inc.
   170 W. Tasman Drive
   San Jose, CA 95134-1706
   United States

   EMail: dmm@cisco.com


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

   EMail: roll@sprint.net

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