INTERNET DRAFT Jung-Soo Park
Expires: October 2002 Myung-Ki Shin
Yong-Jin Kim
ETRI
April 2002
Link Scoped IPv6 Multicast Addresses
<draft-ietf-ipv6-link-scoped-mcast-00.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
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at anytime. It is inappropriate to use Internet Drafts as reference
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
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Abstract
This document specifies an extension to the multicast addressing
architecture of the IPv6 protocol. The extension allows for the
use of interface-ID to allocate multicast addresses. When the
link-local unicast address is configured at each interface of host,
interface ID is uniquely determined. By delegating multicast
addresses at the same time as interface ID, each host can identify
their multicast addresses automatically at Layer 1 without running
an intra- or inter-domain allocation protocol in the serverless
environments.
Table of Contents:
1. Introduction
2. Terminology
3. Applicability
4. Link scoped multicast address format
5. Examples
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6. Considerations
7. Security considerations
8. References
9. Acknowledgements
1. Introduction
This specification defines an extension to the multicast portion of
the IPv6 addressing architecture [ADDRARCH]. The current
architecture does not contain any built-in support for dynamic
address allocation. The extension allows for using interface-ID to
allocate multicast addresses. When the link-local unicast address
is configured at each interface of host, interface ID is uniquely
determined. By delegating multicast addresses at the same time as
interface ID, each host can identify its multicast addresses
automatically without running an intra- or inter-domain allocation
protocol in the serveless environments.
The current multicast address allocation architecture [RFC 2908] is
based on a multi-layered, multi-protocol system. The goal of this
proposal is to reduce the number of protocols and servers to get
dynamic multicast address allocation.
The use of interface ID-based multicast address allocation will, at
a minimum, remove the need to run the Multicast Address Allocation
Protocol (AAP) [AAP WORK][RFC 2909] and the Multicast Address
Allocation servers [RFC 2908].
This document specifies encoded information in the link scoped
multicast address to allow for dynamic allocation of IPv6 multicast
addresses.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC 2119].
3. Applicability
The allocation technique in this document is designed to be used in
any environment in which link-local scope IPv6 multicast addresses
are assigned or selected. Especially, this method goes well with
nodes supplying multicast services in a zeroconf environment. For
example, multicast addresses less than or equal to link-local scope
are generated itself by nodes supplying multicast services.
Consequently, this technique is limited to use by multicast scope.
If you want to use greater multicast addresses than link-local, you
need to get other methods.
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4. Link scoped multicast address format
Section 2.7 of [ADDRARCH] defines the following operational format
of IPv6 multicast addresses:
| 8 | 4 | 4 | 112 |
+--------+----+----+---------------------------------------------+
|11111111|flgs|scop| group ID |
+--------+----+----+---------------------------------------------+
Figure 1: Generic IPv6 multicast address format
This document introduces new formats that incorporate interface ID
information in the multicast address. The idea delegating
multicast addresses at the same time as interface ID, can be
applicable to link-local.
Figure 2 illustrates the new format for link-local multicast
addresses.
| 8 | 4 | 4 | 16 | 64 | 32 |
+--------+----+----+------------+----------------+---------------+
|11111111|flgs|scop| reserved | Interface ID | group ID |
+--------+----+----+------------+----------------+---------------+
Figure 2: link scoped multicast address format
+-+-+-+-+
flgs is a set of 4 flags: |0|0|P|T|
+-+-+-+-+
o P = 0 indicates a multicast address that is not assigned
based on the interface ID.
o P = 1 indicates a multicast address that is assigned
based on the interface ID.
o If P = 1, T MUST be set to 1, otherwise the setting of
the T bit is defined in Section 2.7 of RFC 2373.
flgs should use the same flag defined in section 3 of [UNIMULTI].
That is, this document proposes the third bit of 'flgs' field to
indicates a Interface ID-based multicast addresses. Additionly,
it is required to distinguish between Inteface ID-based multicast
address and unicast-prefix-based multicast address.
scop <= 2. The scope of this multicast address MUST be independent
of the scope of the unicast address, which derives the interface ID
embedded in the multicast address.
The reserved field MUST be zero.
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interface ID field is used to distinguish each host from others.
And this value is obtained from IEEE EUI-64 based interface
identifier of the link-local unicast IPv6 address.
group ID is generated to indicate multicast application and is used
to guarantee its uniqueness only in host. Also, it may be set based
on the guidelines outlined in [IPV6 GID].
The lifetime of a Interface ID-based multicast address has no
dependency to the Valid Lifetime field in the Prefix Information
option, corresponding to the unicast address being used, contained
in the Router Advertisement message [RFC 2461].
5. Examples
This is an example for interface ID-based multicast address with
link-local scope. For example in ethernet environment, if the IEEE
48-bit MAC's address is 12:34:56:78:90:AB, the mutlicast prefix of
a host is FF32:0:1234:56FF:FE78:90AB::/96.
6. Considerations
This draft considers only the link-local multicast addresses. For
this purpose, P flag is used in figure 2. [UNIMULTI] draft also use
the P flag to indicate multicast address that is assigned based on
network prefix. For consistency, some modifications in [UNIMULTI]
draft are required. For example, by restrictng the syntax to
scope > 2 in [UNIMULTI].
7. Security considerations
[RFC3041] describes the privacy extension to IPv6 stateless
address autoconfiguration for interface ID. So, [RFC3041]
satisfied our requirements.
8. References
[RFC 2373]
R. Hinden and S. Deering, "IP Version 6 Addressing Architecture",
RFC 2373, July 1998.
[RFC 2460]
S. Deering and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC 2460, December 1998.
[RFC 2461]
Narten, T., Nordmark, E., Simpson, W., "Neighbor Discovery for IP
Version 6 (IPv6)", RFC 2461, December 1998.
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[RFC 2464]
M. Crawford, "Transmission of IPv6 Packets over Ethernet Networks,"
RFC2464, December 1998
[RFC 2908]
D. Thaler, M. Handley and D. Estrin, "Th Internet Multicast Address
Allocation Architecture," RFC2908, September 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.
[RFC 3041]
T. Narten and R. Draves, "Privacy Extensions for Stateless Address
Autoconfiguration in IPv6," RFC 3041, January 2001.
[RFC 3138]
Meyer, D., "Extended Assignments in 233/8", RFC 3138, June 2001.
[RFC 3180]
Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8", RFC 3180,
September 2001.
[AAP WORK]
Handley, M. and S. Hanna, "Multicast Address Allocation Protocol
(AAP)", Work in Progress.
[ADDRARCH]
R. Hinden and S. Deering, "IP Version 6 Addressing Architecture",
Work In Progress, July 2001.
[UNIMULTI]
B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 Multicast
Addresses," Work In Progress, December 2001.
[IPV6 GID]
B. Haberman, "Dynamic Allocation Guidelines for IPv6 Multicast
Addresses," Work In Progress, October 2001.
9. Acknowledgements
We would like to thank Dave Thaler for his comments related to the
consistency between the unicast prefix-based multicast draft and
this one.
Authors Addresses
Jung-Soo Park
ETRI PEC
161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea
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Internet-Draft Link scoped IPv6 Multicast Addresses Apr. 2002
Tel : +82 42 860 6514
Fax : +82 42 861 5404
E-mail : jspark@pec.etri.re.kr
Myung-Ki Shin
ETRI PEC
161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea
Tel : +82 42 860 4847
Fax : +82 42 861 5404
E-mail : mkshin@pec.etri.re.kr
Yong-Jin Kim
ETRI PEC
161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea
Tel : +82 42 860 6564
Fax : +82 42 861 5404
E-mail : yjkim@pec.etri.re.kr
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