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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 WG 3 Internet Draft Jung-Soo Park 4 draft-ietf-ipv6-link-scoped-mcast-03.txt Myung-Ki Shin 5 Hyoung-Jun Kim 6 ETRI 7 Expires: December 2003 June 2003 9 Link Scoped IPv6 Multicast Addresses 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet-Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt 27 The list of Internet-Draft Shadow Directories can be accessed at 28 http://www.ietf.org/shadow.html. 30 For potential updates to the above required-text see: 31 http://www.ietf.org/ietf/1id-guidelines.txt 33 Abstract 35 This document specifies an extension to the multicast addressing 36 architecture of the IPv6 protocol. The extension allows for the use 37 of interface-IDs to allocate multicast addresses. When the link- 38 local unicast address is configured at each interface of a host, an 39 interface ID is uniquely determined. By delegating multicast 40 addresses at the same time as the interface ID, each host can 41 identify their multicast addresses automatically at Layer 1 without 42 running an intra- or inter-domain allocation protocol in serverless 43 environments. Basically this document updates the "Unicast-Prefix- 44 based IPv6 Multicast Addresses" for the link-local scope [RFC 3306]. 46 Table of Contents 48 1. Introduction...................................................2 49 2. Applicability..................................................2 50 3. Link scoped multicast address format...........................2 51 4. Examples.......................................................4 52 5. Considerations.................................................4 53 6. Security Considerations........................................4 54 7. References.....................................................4 55 8. Acknowledgments................................................5 56 Author's Addresses................................................5 58 1. Introduction 60 This specification defines an extension to the multicast portion of 61 the IPv6 addressing architecture [ADDRARCH]. The current 62 architecture does not contain any built-in support for dynamic 63 address allocation. The extension allows for use of interface-IDs to 64 allocate multicast addresses. When the link-local unicast address is 65 configured at each interface of a host, an interface ID is uniquely 66 determined. By delegating multicast addresses at the same time as 67 the interface ID, each host can identify its multicast addresses 68 automatically without running an intra- or inter-domain allocation 69 protocol in serverless environments. 71 The current multicast address allocation architecture [RFC 2908] is 72 based on a multi-layered, multi-protocol system. The goal of this 73 proposal is to reduce the number of protocols and servers to get 74 dynamic multicast address allocation. 76 The use of interface ID-based multicast address allocation will, at a 77 minimum, remove the need to run the Multicast Address-Set Claim(MASC) 78 Protocol[RFC 2909] and the Multicast Address Allocation servers [RFC 79 2908]. 81 Basically this document updates the "Unicast-Prefix-based IPv6 82 Multicast Addresses" for the link-local scope [RFC 3306]. This 83 document changes and restricts the usage of defined fields such as 84 scope, plen and network prefix field in [RFC 3306]. Therefore, this 85 document specifies encoded information for link-local scope in the 86 multicast addresses. 88 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 89 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 90 document are to be interpreted as described in RFC-2119. 92 2. Applicability 94 The allocation technique in this document is designed to be used in 95 any environment in which link-local scope IPv6 multicast addresses 96 are assigned or selected. Especially, this method goes well with 97 nodes supplying multicast services in a zeroconf environment. For 98 example, multicast addresses less than or equal to link-local scope 99 are themselves generated by nodes supplying multicast services. 101 Consequently, this technique MIUST be used for link scoped multicast 102 addresses. If you want to use multicast addresses greater than link- 103 local, you need other methods such as [RFC 3306]. 105 3. Link scoped multicast address format 107 Section 2.7 of [ADDRARCH] defines the following operational format of 108 IPv6 multicast addresses: 110 | 8 | 4 | 4 | 112 | 111 +--------+----+----+---------------------------------------------+ 112 |11111111|flgs|scop| group ID | 113 +--------+----+----+---------------------------------------------+ 115 Figure 1: Generic IPv6 multicast address format 117 This document introduces new formats that incorporate interface ID 118 information in the multicast address. The idea of delegating 119 multicast addresses at the same time as the interface ID can be 120 applicable to link-local. 122 Figure 2 illustrates the new format for link scoped multicast 123 addresses. That is, if the scope of the multicast address is link- 124 local scope, it is this format. 126 | 8 | 4 | 4 | 16 | 64 | 32 | 127 +--------+----+----+------------+----------------+---------------+ 128 |11111111|flgs|scop| reserved | Interface ID | group ID | 129 +--------+----+----+------------+----------------+---------------+ 131 Figure 2: link scoped multicast IPv6 address format 133 +-+-+-+-+ 134 flgs is a set of 4 flags: |0|0|P|T| 135 +-+-+-+-+ 137 o P = 0 indicates a multicast address that is not assigned 138 on the basis of the interface ID. 139 o P = 1 indicates a multicast address that is assigned 140 on the basis of the interface ID. 141 o If P = 1, T MUST be set to 1, otherwise the setting of 142 the T bit is defined in Section 2.7 of [RFC 2373]. 144 flgs should use the same flag defined in section 4 of [RFC 3306]. 145 That is, this document proposes the third bit of 'flgs' field to 146 indicate an Interface ID-based multicast addresses. 148 scop <= 2. The value of this multicast address is necessary to 149 distinguish between an Interface ID-based multicast address and a 150 unicast-prefix-based multicast address. If scop <= 2, the former MUST 151 be used. That is, this document updates the [RFC 3306], which 152 describes the latter. 154 The reserved field MUST be zero which maps to a plen of zero in RFC 155 3306. 157 Interface ID field is used to distinguish each host from others. And 158 this value is obtained from the IEEE EUI-64 based interface 159 identifier of the link-local unicast IPv6 address. Given the use of 160 this method for link-local scope, the interface ID embedded in the 161 multicast address SHOULD come from the interface ID of the link-local 162 unicast address on the interface after DAD has completed. That is, 163 the creation of the multicast address MUST occur after DAD has 164 completed as part of the auto-config process. 166 Group ID is generated to indicate multicast application and is used 167 to guarantee its uniqueness only in the host. It may also be set on 168 the basis of the guidelines outlined in [RFC 3307]. 170 The lifetime of an Interface ID-based multicast address has no 171 dependency on the Valid Lifetime field in the Prefix Information 172 option, corresponding to the unicast address being used, contained in 173 the Router Advertisement message [RFC 2461]. 175 4. Examples 177 This is an example of an interface ID-based multicast address with 178 link-local scope. For example in an Ethernet environment, if the 179 link-local unicast address is FE80::12:34:56:78:90:AB, the multicast 180 prefix of the host is FF32:0:1234:56FF:FE78:90AB::/96. For SSM, 181 multicast address will be FF32::/96. 183 5. Considerations 185 This document updates [RFC 3306] for the scope <= 2 case. 187 This document considers only link scoped multicast addresses. For 188 this purpose, scop field is used shown in figure 2. 190 The link scoped multicast address format supports source-specific 191 multicast addresses by the same method, as defined by [RFC 3306]. So, 192 it could be confused with a RFC 3306 SSM address. To resolve this, 193 the usage of this format is restricted within link-local scope. 195 6. Security Considerations 197 [RFC 3041] describes the privacy extension to IPv6 stateless address 198 autoconfiguration for an interface ID. The interface ID, generated by 199 [RFC 3041], is also used in this method since the uniqueness is 200 verified by DAD procedure as part of the secure auto-config process. 202 Using source-specific multicast addresses can sometimes aid in the 203 prevention of denial-of-service attacks by arbitrary sources, 204 although no guarantee is provided. A more in-depth discussion of the 205 security considerations for SSM can be found in [SSM ARCH]. 207 7. References 209 Normative 211 [RFC 2119] S. Bradner, "Key words for use in RFCs to indicate 212 Requirement Levels", RFC 2119, March 1997. 214 [RFC 2373] R. Hinden and S. Deering, "IP Version 6 Addressing 215 Architecture", RFC 2373, October 1998. 217 [RFC 3041] T. Narten and R. Draves, "Privacy Extensions for 218 Stateless Address Autoconfiguration in IPv6," RFC 3041, 219 April 2001. 221 [RFC 3306] B. Haberman and D. Thaler, "Unicast-Prefix-based IPv6 222 Multicast Addresses," RFC 3306, August 2002. 224 [ADDRARCH] R. Hinden and S. Deering, "IP Version 6 Addressing 225 Architecture", Work In Progress, October 2002. 227 Informative 229 [RFC 2461] T. Narten, E. Nordmark and W. Simpson, "Neighbor 230 Discovery for IP Version 6 (IPv6)", RFC 2461, December 231 1998. 233 [RFC 2908] D. Thaler, M. Handley and D. Estrin, "The Internet 234 Multicast Address Allocation Architecture," RFC2908, 235 September 2000. 237 [RFC 2909] P. Radoslavov, D. Estrin, R. Govindan, M. Handley, 238 S. Kumar, and D. Thaler, "The Multicast Address-Set Claim 239 (MASC) Protocol", RFC 2909, September 2000. 241 [RFC 3307] B. Haberman, "Dynamic Allocation Guidelines for IPv6 242 Multicast Addresses," Work In Progress, October 2001. 244 [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast for 245 IP", Work In Progress, March 2003. 247 8. Acknowledgments 249 We would like to thank Dave Thaler and Brian Haberman for his 250 comments related to the consistency between the unicast prefix-based 251 multicast draft and this one. 253 Author's Addresses 255 Jung-Soo Park 256 ETRI PEC 257 161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea 258 Phone: +82 42 860 6514 259 Email: jspark@pec.etri.re.kr 261 Myung-Ki Shin 262 ETRI PEC 263 161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea 264 Phone: +82 42 860 4847 265 Email: mkshin@pec.etri.re.kr 267 Hyoung-Jun Kim 268 ETRI PEC 269 161 Gajeong-Dong, Yuseong-Gu, Daejon 305-600, Korea 270 Phone: +82 42 860 6576 271 Email: khj@etri.re.kr