Network Working Group D. Meyer
Request for Comments: 2770 Cisco Systems
Category: Experimental P. Lothberg
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 (C) The Internet Society (2000). All Rights Reserved.
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 <firstname.lastname@example.org> or
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.
Meyer & Lothberg Experimental [Page 1]RFC 2770 GLOP Addressing in 233/8 February 2000
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
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 |
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.
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
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.
Meyer & Lothberg Experimental [Page 2]RFC 2770 GLOP Addressing in 233/8 February 20004. 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].