draft-ietf-ipv6-link-scoped-mcast-02.txt   draft-ietf-ipv6-link-scoped-mcast-03.txt 
INTERNET DRAFT Jung-Soo Park IPv6 WG
Expires: April 2003 Myung-Ki Shin Internet Draft Jung-Soo Park
draft-ietf-ipv6-link-scoped-mcast-03.txt Myung-Ki Shin
Hyoung-Jun Kim
ETRI ETRI
October 2002 Expires: December 2003 June 2003
Link Scoped IPv6 Multicast Addresses Link Scoped IPv6 Multicast Addresses
<draft-ietf-ipv6-link-scoped-mcast-02.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
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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 architecture of the IPv6 protocol. The extension allows for the use
use of interface-IDs to allocate multicast addresses. When the of interface-IDs to allocate multicast addresses. When the link-
link-local unicast address is configured at each interface of a host, local unicast address is configured at each interface of a host, an
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 identify addresses at the same time as the interface ID, each host can
their multicast addresses automatically at Layer 1 without running identify their multicast addresses automatically at Layer 1 without
an intra- or inter-domain allocation protocol in serverless running an intra- or inter-domain allocation protocol in serverless
environments. environments. Basically this document updates the "Unicast-Prefix-
based IPv6 Multicast Addresses" for the link-local scope [RFC 3306].
Table of Contents: Table of Contents
1. Introduction 1. Introduction...................................................2
2. Terminology 2. Applicability..................................................2
3. Applicability 3. Link scoped multicast address format...........................2
4. Link scoped multicast address format 4. Examples.......................................................4
5. Source-specific multicast addresses 5. Considerations.................................................4
6. Examples 6. Security Considerations........................................4
7. Considerations 7. References.....................................................4
8. Security considerations 8. Acknowledgments................................................5
9. References Author's Addresses................................................5
10. Acknowledgements
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 [ADDRARCH]. The current the IPv6 addressing architecture [ADDRARCH]. 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 to address allocation. The extension allows for use of interface-IDs to
allocate multicast addresses. When the link-local unicast address allocate multicast addresses. When the link-local unicast address is
is configured at each interface of a host, an interface ID is uniquely configured at each interface of a host, an interface ID is uniquely
determined. By delegating multicast addresses at the same time as determined. By delegating multicast addresses at the same time as
the interface ID, each host can identify its multicast addresses the interface ID, each host can identify its multicast addresses
automatically without running an intra- or inter-domain allocation automatically without running an intra- or inter-domain allocation
protocol in serveless environments. protocol in serverless environments.
The current multicast address allocation architecture [RFC 2908] is The current multicast address allocation architecture [RFC 2908] is
based on a multi-layered, multi-protocol system. The goal of this based on a multi-layered, multi-protocol system. The goal of this
proposal is to reduce the number of protocols and servers to get proposal is to reduce the number of protocols and servers to get
dynamic multicast address allocation. dynamic multicast address allocation.
The use of interface ID-based multicast address allocation will, at The use of interface ID-based multicast address allocation will, at a
a minimum, remove the need to run the Multicast Address Allocation minimum, remove the need to run the Multicast Address-Set Claim(MASC)
Protocol (AAP) [AAP WORK][RFC 2909] and the Multicast Address Protocol[RFC 2909] and the Multicast Address Allocation servers [RFC
Allocation servers [RFC 2908]. 2908].
This document specifies encoded information in the link scoped
multicast address to allow for dynamic allocation of IPv6 multicast
addresses.
2. Terminology Basically this document updates the "Unicast-Prefix-based IPv6
Multicast Addresses" for the link-local scope [RFC 3306]. This
document changes and restricts the usage of defined fields such as
scope, plen and network prefix field in [RFC 3306]. Therefore, this
document specifies encoded information for link-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
this document are to be interpreted as described in [RFC 2119]. document are to be interpreted as described in RFC-2119.
2. Applicability
3. 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 environment. For
example, multicast addresses less than or equal to link-local scope example, multicast addresses less than or equal to link-local scope
are themselves generated by nodes supplying multicast services. are themselves generated by nodes supplying multicast services.
Consequently, this technique is limited to use by multicast scope. Consequently, this technique MIUST be used for link scoped multicast
If you want to use multicast addresses greater than link-local, you addresses. If you want to use multicast addresses greater than link-
need other methods. local, you need other methods such as [RFC 3306].
4. Link scoped multicast address format 3. Link scoped multicast address format
Section 2.7 of [ADDRARCH] defines the following operational format Section 2.7 of [ADDRARCH] defines the following operational format of
of IPv6 multicast addresses: IPv6 multicast addresses:
| 8 | 4 | 4 | 112 | | 8 | 4 | 4 | 112 |
+--------+----+----+---------------------------------------------+ +--------+----+----+---------------------------------------------+
|11111111|flgs|scop| group ID | |11111111|flgs|scop| group ID |
+--------+----+----+---------------------------------------------+ +--------+----+----+---------------------------------------------+
Figure 1: Generic IPv6 multicast address format Figure 1: Generic IPv6 multicast address format
This document introduces new formats that incorporate interface ID This document introduces new formats that incorporate interface ID
information in the multicast address. The idea of delegating information in the multicast address. 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.
Figure 2 illustrates the new format for link-local multicast Figure 2 illustrates the new format for link scoped multicast
addresses. addresses. That is, if the scope of the multicast address is link-
local scope, it is this format.
| 8 | 4 | 4 | 16 | 64 | 32 | | 8 | 4 | 4 | 16 | 64 | 32 |
+--------+----+----+------------+----------------+---------------+ +--------+----+----+------------+----------------+---------------+
|11111111|flgs|scop| reserved | Interface ID | group ID | |11111111|flgs|scop| reserved | Interface ID | group ID |
+--------+----+----+------------+----------------+---------------+ +--------+----+----+------------+----------------+---------------+
Figure 2: link scoped multicast address format Figure 2: link scoped multicast IPv6 address format
+-+-+-+-+ +-+-+-+-+
flgs is a set of 4 flags: |0|0|P|T| flgs is a set of 4 flags: |0|0|P|T|
+-+-+-+-+ +-+-+-+-+
o P = 0 indicates a multicast address that is not assigned o P = 0 indicates a multicast address that is not assigned
on the basis of the interface ID. on the basis of the interface ID.
o P = 1 indicates a multicast address that is assigned o P = 1 indicates a multicast address that is assigned
on the basis of the interface ID. on the basis of the interface ID.
o If P = 1, T MUST be set to 1, otherwise the setting of 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. the T bit is defined in Section 2.7 of [RFC 2373].
flgs should use the same flag defined in section 3 of [UNIMULTI]. flgs should use the same flag defined in section 4 of [RFC 3306].
That is, this document proposes the third bit of 'flgs' field to That is, this document proposes the third bit of 'flgs' field to
indicates an Interface ID-based multicast addresses. Additionally, indicate an Interface ID-based multicast addresses.
it is necessary to distinguish between an Inteface ID-based multicast
address and a unicast-prefix-based multicast address.
scop <= 2. The scope of this multicast address MUST be independent scop <= 2. The value of this multicast address is necessary to
of the scope of the unicast address, which derives the interface ID distinguish between an Interface ID-based multicast address and a
embedded in the multicast address. unicast-prefix-based multicast address. If scop <= 2, the former MUST
be used. That is, this document updates the [RFC 3306], which
describes the latter.
The reserved field MUST be zero. The reserved field MUST be zero which maps to a plen of zero in RFC
3306.
interface ID field is used to distinguish each host from others. Interface ID field is used to distinguish each host from others. And
And this value is obtained from the IEEE EUI-64 based interface this value is obtained from the IEEE EUI-64 based interface
identifier of the link-local unicast IPv6 address. identifier of the link-local unicast IPv6 address. Given the use of
this method for link-local scope, the interface ID embedded in the
multicast address SHOULD come from the interface ID of the link-local
unicast address on the interface after DAD has completed. That is,
the creation of the multicast address MUST 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 on to guarantee its uniqueness only in the host. It may also be set on
the basis of the guidelines outlined in [IPV6 GID]. the basis of the guidelines outlined in [RFC 3307].
The lifetime of an Interface ID-based multicast address has no The lifetime of an Interface ID-based multicast address has no
dependency on the Valid Lifetime field in the Prefix Information dependency on the Valid Lifetime field in the Prefix Information
option, corresponding to the unicast address being used, contained option, corresponding to the unicast address being used, contained in
in the Router Advertisement message [RFC 2461]. the Router Advertisement message [RFC 2461].
5. Source-specific multicast addresses
The link scoped multicast address format supports source-specific
multicast addresses, as defined by [SSM ARCH]. To accomplish this,
a node MUST:
o Set P = 1. 4. Examples
o Set interface ID = 0.
These settings create an SSM range of FF32::/96. The source address This is an example of an interface ID-based multicast address with
field in the IPv6 header identifies the owner of the multicast link-local scope. For example in an Ethernet environment, if the
address. link-local unicast address is FE80::12:34:56:78:90:AB, the multicast
prefix of the host is FF32:0:1234:56FF:FE78:90AB::/96. For SSM,
multicast address will be FF32::/96.
6. Examples 5. Considerations
This is an example of an interface ID-based multicast address with This document updates [RFC 3306] for the scope <= 2 case.
link-local scope. For example in an ethernet environment, if the
link-local unicast address is FE80::12:34:56:78:90:AB,
the mutlicast prefix of the host is FF32:0:1234:56FF:FE78:90AB::/96.
For SSM, multicast adrress will be FF32::/96.
7. Considerations This document considers only link scoped multicast addresses. For
this purpose, scop field is used shown in figure 2.
This draft considers only link-local multicast addresses. For The link scoped multicast address format supports source-specific
this purpose, P flag is used in figure 2. The [UNIMULTI] draft also multicast addresses by the same method, as defined by [RFC 3306]. So,
uses the P flag to indicate a multicast address that is assigned on it could be confused with a RFC 3306 SSM address. To resolve this,
the basis of the network prefix. For consistency, some modifications the usage of this format is restricted within link-local scope.
in the [UNIMULTI] draft are required. For example, by restrictng the
syntax to scope > 2 in [UNIMULTI].
8. Security considerations 6. Security Considerations
[RFC3041] describes the privacy extension to IPv6 stateless [RFC 3041] describes the privacy extension to IPv6 stateless address
address autoconfiguration for an interface ID. So, [RFC3041] autoconfiguration for an interface ID. The interface ID, generated by
satisfied our requirements. [RFC 3041], is also used in this method since the uniqueness is
verified by DAD procedure as part of the secure auto-config process.
Using source-specific multicast addresses can sometimes aid in the Using source-specific multicast addresses can sometimes aid in the
prevention of denial-of-service attacks by arbitrary sources, prevention of denial-of-service attacks by arbitrary sources,
although no guarantee is provided. A more in-depth discussion of although no guarantee is provided. A more in-depth discussion of the
the security considerations for SSM can be found in [SSM ARCH]. security considerations for SSM can be found in [SSM ARCH].
9. References 7. References
[RFC 2373] Normative
R. Hinden and S. Deering, "IP Version 6 Addressing Architecture",
RFC 2373, October 1998.
[RFC 2461] [RFC 2119] S. Bradner, "Key words for use in RFCs to indicate
Narten, T., Nordmark, E., Simpson, W., "Neighbor Discovery for IP Requirement Levels", RFC 2119, March 1997.
Version 6 (IPv6)", RFC 2461, December 1998.
[RFC 2908] [RFC 2373] R. Hinden and S. Deering, "IP Version 6 Addressing
D. Thaler, M. Handley and D. Estrin, "Th Internet Multicast Address Architecture", RFC 2373, October 1998.
Allocation Architecture," RFC2908, September 2000.
[RFC 2909] [RFC 3041] T. Narten and R. Draves, "Privacy Extensions for
Radoslavov, P., Estrin, D., Govindan, R., Handley, M., Kumar, S. Stateless Address Autoconfiguration in IPv6," RFC 3041,
and D. Thaler, "The Multicast Address-Set Claim (MASC) Protocol", April 2001.
RFC 2909, September 2000.
[RFC 3041] [RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6
T. Narten and R. Draves, "Privacy Extensions for Stateless Address Multicast Addresses," RFC 3306, August 2002.
Autoconfiguration in IPv6," RFC 3041, April 2001.
[AAP WORK] [ADDRARCH] R. Hinden and S. Deering, "IP Version 6 Addressing
Handley, M. and S. Hanna, "Multicast Address Allocation Protocol Architecture", Work In Progress, October 2002.
(AAP)", Work in Progress.
[ADDRARCH] Informative
R. Hinden and S. Deering, "IP Version 6 Addressing Architecture",
Work In Progress, October 2001.
[UNIMULTI] [RFC 2461] T. Narten, E. Nordmark and W. Simpson, "Neighbor
B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 Multicast Discovery for IP Version 6 (IPv6)", RFC 2461, December
Addresses," Work In Progress, December 2001. 1998.
[IPV6 GID] [RFC 2908] D. Thaler, M. Handley and D. Estrin, "The Internet
B. Haberman, "Dynamic Allocation Guidelines for IPv6 Multicast Multicast Address Allocation Architecture," RFC2908,
Addresses," Work In Progress, October 2001. September 2000.
[SSM ARCH] [RFC 2909] P. Radoslavov, D. Estrin, R. Govindan, M. Handley,
H. Holbrook and B. Cain, "Source-Specific Multicast for IP", S. Kumar, and D. Thaler, "The Multicast Address-Set Claim
Work In Progress, March 2001. (MASC) Protocol", RFC 2909, September 2000.
10. Acknowledgements [RFC 3307] B. Haberman, "Dynamic Allocation Guidelines for IPv6
Multicast Addresses," Work In Progress, October 2001.
We would like to thank Dave Thaler for his comments related to the [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast for
consistency between the unicast prefix-based multicast draft and IP", Work In Progress, March 2003.
this one.
Authors Addresses 8. Acknowledgments
We would like to thank Dave Thaler and Brian Haberman for his
comments related to the consistency between the unicast prefix-based
multicast draft and this one.
Author's Addresses
Jung-Soo Park Jung-Soo Park
ETRI PEC ETRI PEC
161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea 161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea
Tel : +82 42 860 6514 Phone: +82 42 860 6514
Fax : +82 42 861 5404 Email: jspark@pec.etri.re.kr
E-mail : jspark@pec.etri.re.kr
Myung-Ki Shin Myung-Ki Shin
ETRI PEC ETRI PEC
161 Kajong-Dong, Yusong-Gu, Taejon 305-600, Korea 161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea
Tel : +82 42 860 4847 Phone: +82 42 860 4847
Fax : +82 42 861 5404 Email: mkshin@pec.etri.re.kr
E-mail : mkshin@pec.etri.re.kr
Hyoung-Jun Kim
ETRI PEC
161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea
Phone: +82 42 860 6576
Email: khj@etri.re.kr
 End of changes. 

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