draft-ietf-ipv6-link-scoped-mcast-04.txt   draft-ietf-ipv6-link-scoped-mcast-05.txt 
IPv6 Working Group J-S. Park IPv6 Working Group J-S. Park
INTERNET DRAFT ETRI INTERNET DRAFT ETRI
Expires: January 2005 M-K. Shin Expires: February 2005 M-K. Shin
ETRI/NIST ETRI/NIST
H-J. Kim H-J. Kim
ETRI ETRI
July 2004 August 2004
Link Scoped IPv6 Multicast Addresses Link Scoped IPv6 Multicast Addresses
<draft-ietf-ipv6-link-scoped-mcast-04.txt> <draft-ietf-ipv6-link-scoped-mcast-05.txt>
Status of this Memo Status of this Memo
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and any of which I become aware will be disclosed, in accordance and any of which I become aware will be disclosed, in accordance
with RFC 3668. with RFC 3668.
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skipping to change at page 1, line 37 skipping to change at page 1, line 38
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This Internet-Draft will expire on January 2005. This Internet-Draft will expire on February 2005.
Abstract Abstract
This document specifies an extension to the multicast addressing This document specifies an extension to the multicast addressing
architecture of the IPv6 protocol. The extension allows for the use architecture of the IPv6 protocol. The extension allows for the use
of interface-IDs to allocate multicast addresses. When the link- of interface-IDs to allocate multicast addresses. When a link-
local unicast address is configured at each interface of a host, an local unicast address is configured at each interface of a node, an
interface ID is uniquely determined. By delegating multicast interface ID is uniquely determined. By delegating multicast
addresses at the same time as the interface ID, each host can addresses at the same time as the interface ID, each node can
identify their multicast addresses automatically at Layer 1 without generate their unique multicast addresses automatically without
running an intra- or inter-domain allocation protocol in serverless conflicts. Basically, it is preferred to use this method for the
environments. Basically, it is preferred to use this method for the link-local scope rather than unicast-prefix-based IPv6 multicast
link-local scope rather than Unicast-Prefix-based IPv6 Multicast addresses [RFC 3306].
Addresses [RFC 3306].
Table of Contents: Table of Contents:
1. Introduction................................................2 1. Introduction................................................2
2. Applicability...............................................3 2. Applicability...............................................2
3. Link scoped multicast address format........................3 3. Link scoped multicast address format........................2
4. Examples....................................................4 4. Example ....................................................4
5. Considerations..............................................4 5. Considerations..............................................4
6. Security Considerations.....................................5 6. Security Considerations.....................................4
7. Acknowledgments.............................................5 7. References..................................................4
8. References..................................................5 8. Acknowledgments.............................................4
Authors' Addresses.............................................6 Authors' Addresses.............................................5
1. Introduction 1. Introduction
This specification defines an extension to the multicast portion of This specification defines an extension to the multicast portion of
the IPv6 addressing architecture [RFC 3513]. The current the IPv6 addressing architecture [RFC 3513]. The current
architecture does not contain any built-in support for dynamic architecture does not contain any built-in support for dynamic
address allocation. The extension allows for use of interface-IDs address allocation. The extension allows for use of interface-IDs
to allocate multicast addresses. When the link-local unicast to allocate multicast addresses. When a link-local unicast address
address is configured at each interface of a host, an interface ID is configured at each interface of a node, an interface ID is
is uniquely determined. By delegating multicast addresses at the uniquely determined. By delegating multicast addresses at the same
same time as the interface ID, each host can identify its multicast time as the interface ID, each node can generate their unique
addresses automatically without running an intra- or inter-domain multicast addresses automatically without conflicts.
allocation protocol in serverless 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-Set Claim
(MASC) Protocol [RFC 2909] and the Multicast Address Allocation
servers [RFC 2908].
Basically, it is preferred to use this method for the link-local Basically, it is preferred to use this method for the link-local
scope rather than Unicast-Prefix-based IPv6 Multicast Addresses scope rather than unicast-prefix-based IPv6 multicast addresses
[RFC 3306]. This document restricts the usage of defined fields [RFC 3306]. This document restricts the usage of defined fields
such as scope, plen and network prefix field in [RFC 3306]. such as scope, plen and network prefix fields of [RFC 3306].
Therefore, this document specifies encoded information for link- Therefore, this document specifies encoded information for link-
local scope in the multicast addresses. local scope in the multicast addresses.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC 2119]. this document are to be interpreted as described in [RFC 2119].
2. Applicability 2. Applicability
The allocation technique in this document is designed to be used in The allocation technique in this document is designed to be used in
any environment in which link-local scope IPv6 multicast addresses any environment in which link-local scope IPv6 multicast addresses
are assigned or selected. Especially, this method goes well with are assigned or selected. Especially, this method goes well with
nodes supplying multicast services in a zeroconf environment. For nodes supplying multicast services in a zeroconf/serverless
example, multicast addresses less than or equal to link-local scope environment. For example, multicast addresses less than or equal
are themselves generated by nodes supplying multicast services. to link-local scope are themselves generated by nodes supplying
multicast services without conflicts.
Consequently, this technique MUST be used for link scoped multicast Consequently, this technique MUST be used for link scoped multicast
addresses. If you want to use multicast addresses greater than addresses. If you want to use multicast addresses greater than
link- local, you need other methods such as [RFC 3306]. link-local scope, you need other methods such as [RFC 3306].
3. Link scoped multicast address format 3. Link scoped multicast address format
Section 2.7 of [EFC 3513] defines the following operational format [RFC 3306] defines the following format of unicast-prefix-based
of IPv6 multicast addresses: IPv6 multicast addresses:
| 8 | 4 | 4 | 112 | | 8 | 4 | 4 | 8 | 8 | 64 | 32 |
+--------+----+----+---------------------------------------------+ +--------+----+----+--------+--------+----------------+----------+
|11111111|flgs|scop| group ID | |11111111|flgs|scop|reserved| plen | network prefix | group ID |
+--------+----+----+---------------------------------------------+ +--------+----+----+--------+--------+----------------+----------+
Figure 1: Generic IPv6 multicast address format Figure 1: Unicast-Prefix-based IPv6 multicast address format
This document introduces new formats that incorporate interface ID This document specifies a new format that incorporates interface ID
information in the multicast address. The idea of delegating information in the multicast addresses. The idea of delegating
multicast addresses at the same time as the interface ID can be multicast addresses at the same time as the interface ID can be
applicable to link-local. applicable to link-local scope.
Figure 2 illustrates the new format for link scoped multicast Figure 2 illustrates the new format for link scoped multicast
addresses. That is, if the scope of the multicast address is link- addresses.
local scope, it is this format.
| 8 | 4 | 4 | 16 | 64 | 32 | | 8 | 4 | 4 | 8 | 8 | 64 | 32 |
+--------+----+----+------------+----------------+---------------+ +--------+----+----+--------+--------+----------------+----------+
|11111111|flgs|scop| reserved | Interface ID | group ID | |11111111|flgs|scop|reserved| LSM | Interface ID | group ID |
+--------+----+----+------------+----------------+---------------+ +--------+----+----+--------+--------+----------------+----------+
Figure 2: link scoped multicast IPv6 address format Figure 2: Link scoped multicast IPv6 address format
+-+-+-+-+ flgs MUST be "0011". (The first two bits have been yet undefined,
flgs is a set of 4 flags: |0|0|P|T| sent as zero and ignored on receipt.) flgs MUST use the same flag
+-+-+-+-+ defined in section 4 of [RFC 3306].
o P = 0 indicates a multicast address that is not assigned scop MUST be <= 2. It is preferred to use this method for the link-
on the basis of the interface ID. local scope rather than unicast-prefix-based IPv6 multicast
o P = 1 indicates a multicast address that is assigned addresses [RFC 3306].
on the basis of 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 4 of [RFC 3306]. The reserved field MUST be zero.
That is, this document proposes the third bit of 'flgs' field to
indicate an Interface ID-based multicast addresses.
scop MUST be <= 2. It is preferred to use this method for the link- LSM (Link Scoped Multicast) field MUST be "1111 1111" which maps to
local scope rather than Unicast-Prefix-based IPv6 Multicast plen field in [RFC 3306], whereas the plen of [RFC 3306] MUST NOT
Addresses [RFC 3306]. be greater than 64.
The reserved field MUST be zero which maps to a plen of zero in RFC That is, flgs, scop, and LSM fields are used to identify whether an
3306. address is a multicast address as specified in this document and to
be processed any further.
Interface ID field is used to distinguish each host from others. Interface ID field is used to distinguish each node from others.
And this value is obtained from the IEEE EUI-64 based interface And this value is obtained from the IEEE EUI-64 based interface
identifier of the link-local unicast IPv6 address. Given the use identifier of the link-local unicast IPv6 address. Given the use
of this method for link-local scope, the interface ID embedded in of this method for link-local scope, the interface ID embedded in
the multicast address SHOULD come from the interface ID of the the multicast address SHOULD come from the interface ID of the
link-local unicast address on the interface after DAD has link-local unicast address on the interface after DAD has
completed. That is, the creation of the multicast address MUST completed. That is, the creation of the multicast address MUST
occur after DAD has completed as part of the auto-config process. occur after DAD has completed as part of the auto-config process.
Group ID is generated to indicate multicast application and is used Group ID is generated to indicate multicast application and is used
to guarantee its uniqueness only in the host. It may also be set to guarantee its uniqueness only in the host. It may also be set
on the basis of the guidelines outlined in [RFC 3307]. on the basis of the guidelines outlined in [RFC 3307].
The lifetime of an Interface ID-based multicast address has no The lifetime of link scoped multicast addresses has no dependency
dependency on the Valid Lifetime field in the Prefix Information on the Valid Lifetime field in the Prefix Information option,
option, corresponding to the unicast address being used, contained corresponding to the unicast address being used, contained in the
in the Router Advertisement message [RFC 2461]. Router Advertisement message [RFC 2461].
4. Examples 4. Example
This is an example of an interface ID-based multicast address with This is an example of link scoped IPv6 multicast addresses. For
link-local scope. For example in an Ethernet environment, if the example in an ethernet environment, if the link-local unicast
link-local unicast address is FE80::a12:34ff:fe56:7890, the address is FE80::A12:34FF:FE56:7890, the link scoped multicast
multicast prefix of the host is FF32:0:a12:34ff:fe56:7890::/96. prefix of the node is FF32:00FF:A12:34FF:FE56:7890::/96.
5. Considerations 5. Considerations
It is preferred to use this method for scop <= 2 rather than
Unicast-Prefix-based IPv6 Multicast Addresses [RFC 3306]. This
document considers only link scoped multicast addresses. For this
purpose, scop field is used shown in figure 2.
The link scoped multicast address format supports source-specific The link scoped multicast address format supports source-specific
multicast addresses by the same method, as defined by [RFC 3306]. multicast addresses by the same method, as defined by [RFC 3306].
Note that if an SSM implementation checks for FF3x::/32, not
FF3x::/96, the other nodes not implementing this specification will
interpret the link-local multicast addresses generated using this
specification as SSM addresses, since the document uses the
reserved field in such a fashion that plen=0 [RFC 3306]. In order
to avoid this conflict, we recommend SSM implementations must check
for FF3x::/96, as described in Allocation Guidelines for IPv6
Multicast Addresses [RFC 3307] section 3.
6. Security Considerations 6. Security Considerations
[RFC 3041] describes the privacy extension to IPv6 stateless [RFC 3041] describes the privacy extension to IPv6 stateless
address autoconfiguration for an interface ID. The interface ID, address autoconfiguration for an interface ID. The interface ID,
generated by [RFC 3041], is also used in this method since the generated by [RFC 3041], is also used in this method since the
uniqueness is verified by DAD procedure as part of the secure auto- uniqueness is verified by DAD procedure as part of the secure auto-
config process. config process.
Using source-specific multicast addresses can sometimes aid in the
prevention of denial-of-service attacks by arbitrary sources,
although no guarantee is provided. A more in-depth discussion of
the security considerations for SSM can be found in [SSM ARCH].
7. Acknowledgements 7. Acknowledgements
We would like to thank Dave Thaler and Brian Haberman for his We would like to thank Dave Thaler and Brian Haberman for their
comments related to the consistency between the unicast prefix- comments related to the consistency between the unicast prefix-
based multicast draft and this one. Special thanks are due to Erik based multicast addresses [RFC 3306] and this one. Special thanks
Nordmark and Pekka Savola for valuable comments. are due to Erik Nordmark and Pekka Savola for valuable comments.
8. References 8. References
Normative Normative
[RFC 2119] S. Bradner, "Key words for use in RFCs to indicate [RFC 2119] S. Bradner, "Key words for use in RFCs to indicate
Requirement Levels", RFC 2119, March 1997. Requirement Levels", RFC 2119, March 1997.
[RFC 3041] T. Narten and R. Draves, "Privacy Extensions for [RFC 3041] T. Narten and R. Draves, "Privacy Extensions for
Stateless Address Autoconfiguration in IPv6," RFC 3041, Stateless Address Autoconfiguration in IPv6," RFC
April 2001. 3041, April 2001.
[RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 [RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based
Multicast Addresses," RFC 3306, August 2002. IPv6 Multicast Addresses," RFC 3306, August 2002.
[RFC 3307] B. Haberman, "Allocation Guidelines for IPv6 Multicast [RFC 3307] B. Haberman, "Allocation Guidelines for IPv6
Addresses," RFC 3307, August 2002. Multicast Addresses," RFC 3307, August 2002.
[RFC 3513] R. Hinden and S. Deering, "IP Version 6 Addressing [RFC 3513] R. Hinden and S. Deering, "IP Version 6 Addressing
Architecture", RFC 3513, April 2003. Architecture," RFC 3513, April 2003.
Informative Informative
[RFC 2461] T. Narten, E. Nordmark and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461, December
1998.
[RFC 2908] D. Thaler, M. Handley and D. Estrin, "The Internet
Multicast Address Allocation Architecture," RFC 2908,
September 2000.
[RFC 2909] P. Radoslavov, D. Estrin, R. Govindan, M. Handley, [RFC 2461] T. Narten, E. Nordmark and W. Simpson, "Neighbor
S. Kumar, and D. Thaler, "The Multicast Address-Set Claim Discovery for IP Version 6 (IPv6)," RFC 2461,
(MASC) Protocol", RFC 2909, September 2000. December 1998.
[SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast for [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast
IP", Work In Progress, October 2003. for IP," Work In Progress, July 2004.
Authors' Addresses Authors' Addresses
Jung-Soo Park Jung-Soo Park
ETRI PEC ETRI PEC
161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea 161 Gajeong-Dong, Yuseong-Gu, Daejeon 305-350, Korea
Phone: +82 42 860 6514 Phone: +82 42 860 6514
Email: jspark@pec.etri.re.kr Email: jspark@pec.etri.re.kr
Myung-Ki Shin Myung-Ki Shin
ETRI/NIST ETRI/NIST
820 West Diamond Avenue 820 West Diamond Avenue
Gaithersburg, MD 20899, USA Gaithersburg, MD 20899, USA
Tel : +1 301 975-3613 Tel : +1 301 975-3613
Fax : +1 301 590-0932 Fax : +1 301 590-0932
E-mail : mshin@nist.gov E-mail : mshin@nist.gov
Hyoung-Jun Kim Hyoung-Jun Kim
ETRI PEC ETRI PEC
161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea 161 Gajeong-Dong, Yuseong-Gu, Daejeon 305-350, Korea
Phone: +82 42 860 6576 Phone: +82 42 860 6576
Email: khj@etri.re.kr Email: khj@etri.re.kr
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that rights might or might not be available; nor does it represent that
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