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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) == Outdated reference: A later version (-18) exists of draft-ietf-softwire-dslite-multicast-16 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Softwire WG M. Boucadair 3 Internet-Draft Orange 4 Intended status: Standards Track J. Qin 5 Expires: August 5, 2017 Cisco 6 T. Tsou 7 Philips Lighting 8 X. Deng 9 The University of New South Wales 10 February 1, 2017 12 DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6 Prefixes 13 draft-ietf-softwire-multicast-prefix-option-13 15 Abstract 17 This document defines a Dynamic Host Configuration Protocol version 6 18 (DHCPv6) Option for multicast IPv4 service continuity solutions, 19 which is used to carry the IPv6 prefixes to be used to build unicast 20 and multicast IPv4-embedded IPv6 addresses. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on August 5, 2017. 39 Copyright Notice 41 Copyright (c) 2017 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 59 3. OPTION_V6_PREFIX64 DHCPv6 Option . . . . . . . . . . . . . . 3 60 4. Configuration Guidelines for the Server . . . . . . . . . . . 5 61 5. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 5 62 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 63 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 64 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 65 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 66 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 67 9.2. Informative References . . . . . . . . . . . . . . . . . 7 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 70 1. Introduction 72 Several solutions (e.g., [I-D.ietf-softwire-dslite-multicast]) are 73 proposed for the delivery of multicast services in the context of 74 transition to IPv6. Even if these solutions may have different 75 applicable use cases, they all use specific IPv6 addresses that embed 76 IPv4 addresses, for both multicast group and source addresses. 78 This document defines a DHCPv6 option [RFC3315] that carries the IPv6 79 prefixes to be used for constructing these IPv4-embedded IPv6 80 addresses. 82 In particular, this option can be used in the context of DS-Lite 83 [RFC6333], Stateless A+P [RFC6346], and other IPv4-IPv6 transition 84 techniques. 86 1.1. Requirements Language 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 [RFC2119]. 92 2. Terminology 94 This document makes use of the following terms: 96 IPv4-embedded IPv6 address: an IPv6 address which embeds a 32 bit- 97 encoded IPv4 address [RFC6052]. An IPv4-embedded IPv6 address can 98 be a unicast or a multicast address. 100 Prefix64: is an IPv6 prefix used for synthesizing IPv4-embedded IPv6 101 addresses. A Prefix64 can be of unicast or multicast. 103 Note: "64" is used as an abbreviation for IPv6-IPv4 104 interconnection. 106 ASM_mPrefix64: a multicast Prefix64 which belongs to the Any-Source 107 Multicast (ASM) range. 109 SSM_mPrefix64: a multicast Prefix64 which belongs to the Source- 110 Specific Multicast (SSM) [RFC4607] range. 112 uPrefix64: a unicast Prefix64 for building the IPv4-embedded IPv6 113 addresses of multicast sources in SSM mode. 115 3. OPTION_V6_PREFIX64 DHCPv6 Option 117 OPTION_V6_PREFIX64 (Figure 1) conveys the IPv6 prefix(es) to be used 118 (e.g., by an mB4 [I-D.ietf-softwire-dslite-multicast]) to synthesize 119 IPv4-embedded IPv6 addresses. 121 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 123 | OPTION_V6_PREFIX64 | option-length | 124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 125 | asm-length | | 126 +-+-+-+-+-+-+-+-+ : 127 : ASM_mPrefix64 : 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | ssm-length | | 130 +-+-+-+-+-+-+-+-+ : 131 : SSM_mPrefix64 : 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | unicast-length| | 134 +-+-+-+-+-+-+-+-+ : 135 : uPrefix64 (Variable) : 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 Figure 1: OPTION_V6_PREFIX64: Option Format 140 The fields of the option shown in Figure 1 are as follows: 142 option-code: OPTION_V6_PREFIX64 (see Section 8). 144 option-length: length of the option, in octets. 146 asm-length: the prefix-length for the ASM IPv4-embedded prefix, as 147 an 8-bit unsigned integer. This field represents the number of 148 valid leading bits in the prefix. This field MUST be set to 96. 150 ASM_mPrefix64: this field identifies the IPv6 multicast prefix to be 151 used to synthesize the IPv4-embedded IPv6 addresses of the 152 multicast groups in the ASM mode. The conveyed multicast IPv6 153 prefix MUST belong to the ASM range. 155 ssm-length: the prefix-length for the SSM IPv4-embedded prefix, as 156 an 8-bit unsigned integer. This field represents the number of 157 valid leading bits in the prefix. This field MUST be set to 96. 159 SSM_mPrefix64: this field identifies the IPv6 multicast prefix to be 160 used to synthesize the IPv4-embedded IPv6 addresses of the 161 multicast groups in the SSM mode. The conveyed multicast IPv6 162 prefix MUST belong to the SSM range. 164 unicast-length: the prefix-length for the IPv6 unicast prefix to be 165 used to synthesize the IPv4-embedded IPv6 addresses of the 166 multicast sources, as an 8-bit unsigned integer. As specified in 167 [RFC6052], the unicast-length MUST be one of 32, 48, 56, 64, or 168 96. This field represents the number of valid leading bits in the 169 prefix. 171 uPrefix64: this field identifies the IPv6 unicast prefix to be used 172 in SSM mode for constructing the IPv4-embedded IPv6 addresses 173 representing the IPv4 multicast sources in the IPv6 domain. 174 uPrefix64 may also be used to extract the IPv4 address from the 175 received multicast data flows. It is a variable size field with 176 the length of the field defined by the unicast-length field and is 177 rounded up to the nearest octet boundary. In this case, any 178 additional padding bits must be zeroed. The address mapping MUST 179 follow the guidelines documented in [RFC6052]. 181 Multiple instances of OPTION_V6_PREFIX64 may be returned to a DHCPv6 182 client. 184 Note that it was tempting to define three distinct DHCPv6 options, 185 but that approach was not adopted because it has a side effect: the 186 specification of a DHCPv6 option that could be used to discover 187 unicast Prefix64s in environments where multicast is not enabled. 188 Such side effect conflicts with the recommendation to support the 189 Well-Known DNS Name heuristic discovery-based method for unicast-only 190 environments (Section 6 of [RFC7051]). 192 4. Configuration Guidelines for the Server 194 This section is not normative but specifies a set of configuration 195 guidelines. 197 DHCP servers supporting OPTION_V6_PREFIX64 must be configured with 198 ASM_mPrefix64 or SSM_mPrefix64, and may be configured with both. 199 uPrefix64 must also be configured when SSM_mPrefix64 is provided. 200 uPrefix64 may be configured when ASM_mPrefix64 is provided. Note 201 that uPrefix64 is not mandatory for the ASM case if, for example, a 202 local address mapping algorithm is supported or the Well-Know Prefix 203 (64:ff9b::/96) is used. 205 When a multicast Prefix64 (ASM_mPrefix64 or SSM_mPrefix64) is 206 configured, the length of the prefix must be /96. 208 Both ASM_mPrefix64 and SSM_mPrefix64 may be configured and therefore 209 be returned to a requesting DHCP client in the same 210 OPTION_V6_PREFIX64. In particular, if both SSM and ASM modes are 211 supported, ASM_mPrefix64 and SSM_mPrefix64 prefixes must be 212 configured. For SSM deployments, both SSM_mPrefix64 and uPrefix64 213 must be configured. 215 When distinct IPv6 multicast address scopes [RFC7346] are required to 216 preserve the scope when translating IPv4 multicast addresses 217 (Section 8 of [RFC2365]), each scope is configured as a separate 218 OPTION_V6_PREFIX64. How DHCP servers are configured to separate 219 multicast Prefix64 per scope is implementation-specific and not 220 covered by this document. 222 When scope preservation is not required, only one instance of 223 OPTION_V6_PREFIX64 is configured. 225 5. DHCPv6 Client Behavior 227 To retrieve the IPv6 prefixes that will be used to synthesize unicast 228 and multicast IPv4-embedded IPv6 addresses, the DHCPv6 client MUST 229 include OPTION_V6_PREFIX64 code in its OPTION_ORO. If the DHCPv6 230 client receives more than one OPTION_V6_PREFIX64 option from the 231 DHCPv6 server: 233 o If each enclosed IPv6 multicast prefix has a distinct scope 234 [RFC7346], the client MUST select the appropriate IPv6 multicast 235 prefix whose scope matches the IPv4 multicast address used to 236 synthesize an IPv4-embedded IPv6 multicast address. 238 o If at least two of the received options convey IPv6 multicast 239 prefixes that have the same scope, the said options MUST be 240 discarded. 242 If asm-length, ssm-length and unicast-length fields are all set to 0, 243 the DHCPv6 client MUST behave as if OPTION_V6_PREFIX64 had not been 244 received in the response received from the DHCPv6 server. 246 If the asm-length field is non-null, the IPv6 prefix identified by 247 ASM_mPrefix64 is used to synthesize IPv4-embedded IPv6 multicast 248 addresses in the ASM range. This is achieved by concatenating the 249 ASM_mPrefix64 and the IPv4 multicast address; the IPv4 multicast 250 address is inserted in the last 32 bits of the IPv4-embedded IPv6 251 multicast address. 253 If the ssm-length field is non-null, the IPv6 prefix identified by 254 SSM_mPrefix64 is used to synthesize IPv4-embedded IPv6 multicast 255 addresses in the SSM range. This is achieved by concatenating the 256 SSM_mPrefix64 and the IPv4 multicast address; the Pv4 multicast 257 address is inserted in the last 32 bits of the IPv4-embedded IPv6 258 multicast address. 260 If the unicast-length field is non-null, the IPv6 prefix identified 261 by uPrefix64 is used to synthesize IPv4-embedded IPv6 unicast 262 addresses as specified in [RFC6052]. 264 6. Security Considerations 266 The security considerations documented in [RFC3315] and [RFC6052] are 267 to be considered. 269 7. Acknowledgments 271 Thanks to C. Jacquenet, S. Venaas, B. Volz, T. Taylor, R. Weber, 272 R. Even, J. Sheng, and T. Mrugalski for their review. 274 Many thanks to I. Farrer and T. Lemon for the comments. 276 8. IANA Considerations 278 Authors of this document request IANA to assign a new DHCPv6 option 279 code in the registry maintained in http://www.iana.org/assignments/ 280 dhcpv6-parameters: 282 Option Name Value 283 ----------------- ----- 284 OPTION_V6_PREFIX64 TBA 286 9. References 288 9.1. Normative References 290 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 291 Requirement Levels", BCP 14, RFC 2119, 292 DOI 10.17487/RFC2119, March 1997, 293 . 295 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 296 C., and M. Carney, "Dynamic Host Configuration Protocol 297 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 298 2003, . 300 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 301 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 302 . 304 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 305 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 306 DOI 10.17487/RFC6052, October 2010, 307 . 309 9.2. Informative References 311 [I-D.ietf-softwire-dslite-multicast] 312 Boucadair, M., Qin, J., Jacquenet, C., Lee, Y., and Q. 313 Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients 314 over an IPv6 Multicast Network", draft-ietf-softwire- 315 dslite-multicast-16 (work in progress), January 2017. 317 [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, 318 RFC 2365, DOI 10.17487/RFC2365, July 1998, 319 . 321 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 322 Stack Lite Broadband Deployments Following IPv4 323 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, 324 . 326 [RFC6346] Bush, R., Ed., "The Address plus Port (A+P) Approach to 327 the IPv4 Address Shortage", RFC 6346, 328 DOI 10.17487/RFC6346, August 2011, 329 . 331 [RFC7051] Korhonen, J., Ed. and T. Savolainen, Ed., "Analysis of 332 Solution Proposals for Hosts to Learn NAT64 Prefix", 333 RFC 7051, DOI 10.17487/RFC7051, November 2013, 334 . 336 [RFC7346] Droms, R., "IPv6 Multicast Address Scopes", RFC 7346, 337 DOI 10.17487/RFC7346, August 2014, 338 . 340 Authors' Addresses 342 Mohamed Boucadair 343 Orange 344 Rennes 35000 345 France 347 Email: mohamed.boucadair@orange.com 349 Jacni Qin 350 Cisco 351 P.R. China 353 Email: jacni@jacni.com 355 Tina Tsou 356 Philips Lighting 357 United States of America 359 Email: tina.tsou@philips.com 361 Xiaohong Deng 362 The University of New South Wales 363 Sydney NSW 2052 364 Australia 366 Email: dxhbupt@gmail.com