--- 1/draft-ietf-ipv6-link-scoped-mcast-04.txt 2006-02-05 00:02:40.000000000 +0100 +++ 2/draft-ietf-ipv6-link-scoped-mcast-05.txt 2006-02-05 00:02:40.000000000 +0100 @@ -1,20 +1,21 @@ + IPv6 Working Group J-S. Park INTERNET DRAFT ETRI -Expires: January 2005 M-K. Shin +Expires: February 2005 M-K. Shin ETRI/NIST H-J. Kim ETRI - July 2004 + August 2004 Link Scoped IPv6 Multicast Addresses - + Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that @@ -26,264 +27,222 @@ ments at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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 http://www.ietf.org/shadow.html. - This Internet-Draft will expire on January 2005. + This Internet-Draft will expire on February 2005. Abstract This document specifies an extension to the multicast addressing architecture of the IPv6 protocol. The extension allows for the use - of interface-IDs to allocate multicast addresses. When the link- - local unicast address is configured at each interface of a host, an + of interface-IDs to allocate multicast addresses. When a link- + local unicast address is configured at each interface of a node, an interface ID is uniquely determined. By delegating multicast - addresses at the same time as the interface ID, each host can - identify their multicast addresses automatically at Layer 1 without - running an intra- or inter-domain allocation protocol in serverless - environments. Basically, it is preferred to use this method for the - link-local scope rather than Unicast-Prefix-based IPv6 Multicast - Addresses [RFC 3306]. + addresses at the same time as the interface ID, each node can + generate their unique multicast addresses automatically without + conflicts. Basically, it is preferred to use this method for the + link-local scope rather than unicast-prefix-based IPv6 multicast + addresses [RFC 3306]. Table of Contents: 1. Introduction................................................2 - 2. Applicability...............................................3 - 3. Link scoped multicast address format........................3 - 4. Examples....................................................4 + 2. Applicability...............................................2 + 3. Link scoped multicast address format........................2 + 4. Example ....................................................4 5. Considerations..............................................4 - 6. Security Considerations.....................................5 - 7. Acknowledgments.............................................5 - 8. References..................................................5 - Authors' Addresses.............................................6 + 6. Security Considerations.....................................4 + 7. References..................................................4 + 8. Acknowledgments.............................................4 + Authors' Addresses.............................................5 1. Introduction This specification defines an extension to the multicast portion of the IPv6 addressing architecture [RFC 3513]. The current architecture does not contain any built-in support for dynamic address allocation. The extension allows for use of interface-IDs - to allocate multicast addresses. When the link-local unicast - address is configured at each interface of a host, an interface ID - is uniquely determined. By delegating multicast addresses at the - same time as the interface ID, each host can identify its multicast - addresses automatically without running an intra- or inter-domain - 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]. + to allocate multicast addresses. When a link-local unicast address + is configured at each interface of a node, an interface ID is + uniquely determined. By delegating multicast addresses at the same + time as the interface ID, each node can generate their unique + multicast addresses automatically without conflicts. 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 - 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- local scope in the multicast addresses. 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]. 2. 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 themselves generated by nodes supplying multicast services. + nodes supplying multicast services in a zeroconf/serverless + environment. For example, multicast addresses less than or equal + to link-local scope are themselves generated by nodes supplying + multicast services without conflicts. Consequently, this technique MUST be used for link scoped multicast 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 - Section 2.7 of [EFC 3513] defines the following operational format - of IPv6 multicast addresses: + [RFC 3306] defines the following format of unicast-prefix-based + IPv6 multicast addresses: - | 8 | 4 | 4 | 112 | - +--------+----+----+---------------------------------------------+ - |11111111|flgs|scop| group ID | - +--------+----+----+---------------------------------------------+ + | 8 | 4 | 4 | 8 | 8 | 64 | 32 | + +--------+----+----+--------+--------+----------------+----------+ + |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 - information in the multicast address. The idea of delegating + This document specifies a new format that incorporates interface ID + information in the multicast addresses. The idea of delegating 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 - addresses. That is, if the scope of the multicast address is link- - local scope, it is this format. + addresses. - | 8 | 4 | 4 | 16 | 64 | 32 | - +--------+----+----+------------+----------------+---------------+ - |11111111|flgs|scop| reserved | Interface ID | group ID | - +--------+----+----+------------+----------------+---------------+ + | 8 | 4 | 4 | 8 | 8 | 64 | 32 | + +--------+----+----+--------+--------+----------------+----------+ + |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 is a set of 4 flags: |0|0|P|T| - +-+-+-+-+ + flgs MUST be "0011". (The first two bits have been yet undefined, + 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 - on the basis of the interface ID. - o P = 1 indicates a multicast address that is assigned - 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]. + scop MUST be <= 2. It is preferred to use this method for the link- + local scope rather than unicast-prefix-based IPv6 multicast + addresses [RFC 3306]. - 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 - indicate an Interface ID-based multicast addresses. + The reserved field MUST be zero. - scop MUST be <= 2. It is preferred to use this method for the link- - local scope rather than Unicast-Prefix-based IPv6 Multicast - Addresses [RFC 3306]. + LSM (Link Scoped Multicast) field MUST be "1111 1111" which maps to + plen field in [RFC 3306], whereas the plen of [RFC 3306] MUST NOT + be greater than 64. - The reserved field MUST be zero which maps to a plen of zero in RFC - 3306. + That is, flgs, scop, and LSM fields are used to identify whether an + 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 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 to guarantee its uniqueness only in the host. It may also be set on the basis of the guidelines outlined in [RFC 3307]. - The lifetime of an Interface ID-based multicast address has no - dependency on the Valid Lifetime field in the Prefix Information - option, corresponding to the unicast address being used, contained - in the Router Advertisement message [RFC 2461]. + The lifetime of link scoped multicast addresses has no dependency + on the Valid Lifetime field in the Prefix Information option, + corresponding to the unicast address being used, contained in the + Router Advertisement message [RFC 2461]. -4. Examples +4. Example - This is an example of an interface ID-based multicast address with - link-local scope. For example in an Ethernet environment, if the - link-local unicast address is FE80::a12:34ff:fe56:7890, the - multicast prefix of the host is FF32:0:a12:34ff:fe56:7890::/96. + This is an example of link scoped IPv6 multicast addresses. For + example in an ethernet environment, if the link-local unicast + address is FE80::A12:34FF:FE56:7890, the link scoped multicast + prefix of the node is FF32:00FF:A12:34FF:FE56:7890::/96. 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 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 [RFC 3041] describes the privacy extension to IPv6 stateless address autoconfiguration for an interface ID. The interface ID, generated by [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 - 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 - 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- - based multicast draft and this one. Special thanks are due to Erik - Nordmark and Pekka Savola for valuable comments. + based multicast addresses [RFC 3306] and this one. Special thanks + are due to Erik Nordmark and Pekka Savola for valuable comments. 8. References Normative [RFC 2119] S. Bradner, "Key words for use in RFCs to indicate Requirement Levels", RFC 2119, March 1997. [RFC 3041] T. Narten and R. Draves, "Privacy Extensions for - Stateless Address Autoconfiguration in IPv6," RFC 3041, - April 2001. + Stateless Address Autoconfiguration in IPv6," RFC + 3041, April 2001. - [RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 - Multicast Addresses," RFC 3306, August 2002. + [RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based + IPv6 Multicast Addresses," RFC 3306, August 2002. - [RFC 3307] B. Haberman, "Allocation Guidelines for IPv6 Multicast - Addresses," RFC 3307, August 2002. + [RFC 3307] B. Haberman, "Allocation Guidelines for IPv6 + Multicast Addresses," RFC 3307, August 2002. [RFC 3513] R. Hinden and S. Deering, "IP Version 6 Addressing - Architecture", RFC 3513, April 2003. + Architecture," RFC 3513, April 2003. 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, - S. Kumar, and D. Thaler, "The Multicast Address-Set Claim - (MASC) Protocol", RFC 2909, September 2000. + [RFC 2461] T. Narten, E. Nordmark and W. Simpson, "Neighbor + Discovery for IP Version 6 (IPv6)," RFC 2461, + December 1998. - [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast for - IP", Work In Progress, October 2003. + [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast + for IP," Work In Progress, July 2004. Authors' Addresses Jung-Soo Park 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 Email: jspark@pec.etri.re.kr Myung-Ki Shin ETRI/NIST 820 West Diamond Avenue Gaithersburg, MD 20899, USA Tel : +1 301 975-3613 Fax : +1 301 590-0932 E-mail : mshin@nist.gov Hyoung-Jun Kim 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 Email: khj@etri.re.kr Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that