RFC2770 - 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 RFC1797:

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 RFC1797

(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 RFC1797, 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 RFC1797 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)", RFC2730,

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", RFC1797, April 1995.

[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,

selection, and registration of an Autonomous System (AS)",

RFC1930, 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", RFC2374, 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

10. Full Copyright Statement

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