idnits 2.17.1 draft-ietf-softwire-multicast-prefix-option-15.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (February 2, 2017) is 2639 days in the past. Is this intentional? 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) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 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 6, 2017 Cisco 6 T. Tsou 7 Philips Lighting 8 X. Deng 9 The University of New South Wales 10 February 2, 2017 12 DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6 Prefixes 13 draft-ietf-softwire-multicast-prefix-option-15 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 6, 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. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 5 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 62 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 63 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 64 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 66 8.2. Informative References . . . . . . . . . . . . . . . . . 6 67 Appendix A. Configuration Recommendations for DHCP Servers . . . 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 7). 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, 40, 48, 56, 64, 168 or 96. This field represents the number of valid leading bits in 169 the 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. Configuration recommendations for DHCP servers are listed in 183 Appendix A. 185 Note that it was tempting to define three distinct DHCPv6 options, 186 but that approach was not adopted because it has a side effect: the 187 specification of a DHCPv6 option that could be used to discover 188 unicast Prefix64s in environments where multicast is not enabled. 189 Such side effect conflicts with the recommendation to support the 190 Well-Known DNS Name heuristic discovery-based method for unicast-only 191 environments (Section 6 of [RFC7051]). 193 4. DHCPv6 Client Behavior 195 To retrieve the IPv6 prefixes that will be used to synthesize unicast 196 and multicast IPv4-embedded IPv6 addresses, the DHCPv6 client MUST 197 include OPTION_V6_PREFIX64 code in its OPTION_ORO. If the DHCPv6 198 client receives more than one OPTION_V6_PREFIX64 option from the 199 DHCPv6 server: 201 o If each enclosed IPv6 multicast prefix has a distinct scope 202 [RFC7346], the client MUST select the appropriate IPv6 multicast 203 prefix whose scope matches the IPv4 multicast address used to 204 synthesize an IPv4-embedded IPv6 multicast address. 206 o If at least two of the received options convey IPv6 multicast 207 prefixes that have the same scope, the said options MUST be 208 discarded. 210 If asm-length, ssm-length and unicast-length fields are all set to 0, 211 the DHCPv6 client MUST behave as if OPTION_V6_PREFIX64 had not been 212 received in the response received from the DHCPv6 server. 214 If the asm-length field is non-null, the IPv6 prefix identified by 215 ASM_mPrefix64 is used to synthesize IPv4-embedded IPv6 multicast 216 addresses in the ASM range. This is achieved by concatenating the 217 ASM_mPrefix64 and the IPv4 multicast address; the IPv4 multicast 218 address is inserted in the last 32 bits of the IPv4-embedded IPv6 219 multicast address. 221 If the ssm-length field is non-null, the IPv6 prefix identified by 222 SSM_mPrefix64 is used to synthesize IPv4-embedded IPv6 multicast 223 addresses in the SSM range. This is achieved by concatenating the 224 SSM_mPrefix64 and the IPv4 multicast address; the Pv4 multicast 225 address is inserted in the last 32 bits of the IPv4-embedded IPv6 226 multicast address. 228 If the unicast-length field is non-null, the IPv6 prefix identified 229 by uPrefix64 is used to synthesize IPv4-embedded IPv6 unicast 230 addresses as specified in [RFC6052]. 232 5. Security Considerations 234 The security considerations documented in [RFC3315] and [RFC6052] are 235 to be considered. 237 6. Acknowledgments 239 Thanks to C. Jacquenet, S. Venaas, B. Volz, T. Taylor, R. Weber, 240 R. Even, J. Sheng, T. Mrugalski, and T. Chown for their review. 242 Many thanks to I. Farrer and T. Lemon for the comments. 244 7. IANA Considerations 246 Authors of this document request IANA to assign a new DHCPv6 option 247 code in the registry maintained in http://www.iana.org/assignments/ 248 dhcpv6-parameters: 250 Option Name Value 251 ----------------- ----- 252 OPTION_V6_PREFIX64 TBA 254 8. References 256 8.1. Normative References 258 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 259 Requirement Levels", BCP 14, RFC 2119, 260 DOI 10.17487/RFC2119, March 1997, 261 . 263 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 264 C., and M. Carney, "Dynamic Host Configuration Protocol 265 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 266 2003, . 268 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 269 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 270 . 272 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 273 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 274 DOI 10.17487/RFC6052, October 2010, 275 . 277 8.2. Informative References 279 [I-D.ietf-softwire-dslite-multicast] 280 Boucadair, M., Qin, J., Jacquenet, C., Lee, Y., and Q. 281 Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients 282 over an IPv6 Multicast Network", draft-ietf-softwire- 283 dslite-multicast-18 (work in progress), February 2017. 285 [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, 286 RFC 2365, DOI 10.17487/RFC2365, July 1998, 287 . 289 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 290 Stack Lite Broadband Deployments Following IPv4 291 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, 292 . 294 [RFC6346] Bush, R., Ed., "The Address plus Port (A+P) Approach to 295 the IPv4 Address Shortage", RFC 6346, 296 DOI 10.17487/RFC6346, August 2011, 297 . 299 [RFC7051] Korhonen, J., Ed. and T. Savolainen, Ed., "Analysis of 300 Solution Proposals for Hosts to Learn NAT64 Prefix", 301 RFC 7051, DOI 10.17487/RFC7051, November 2013, 302 . 304 [RFC7346] Droms, R., "IPv6 Multicast Address Scopes", RFC 7346, 305 DOI 10.17487/RFC7346, August 2014, 306 . 308 Appendix A. Configuration Recommendations for DHCP Servers 310 This appendix details a set of non-normative configuration 311 recommendations: 313 o DHCP servers supporting OPTION_V6_PREFIX64 must be configured with 314 ASM_mPrefix64 or SSM_mPrefix64, and may be configured with both. 316 o uPrefix64 must also be configured when SSM_mPrefix64 is provided. 318 o uPrefix64 may be configured when ASM_mPrefix64 is provided. 320 Note that uPrefix64 is not mandatory for the ASM case if, for 321 example, a local address mapping algorithm is supported or the 322 Well-Known Prefix (64:ff9b::/96) is used. 324 o Both ASM_mPrefix64 and SSM_mPrefix64 may be configured and 325 therefore be returned to a requesting DHCP client in the same 326 OPTION_V6_PREFIX64. In particular, if both SSM and ASM modes are 327 supported, ASM_mPrefix64 and SSM_mPrefix64 prefixes must be 328 configured. For SSM deployments, both SSM_mPrefix64 and uPrefix64 329 must be configured. 331 o When a multicast Prefix64 (ASM_mPrefix64 or SSM_mPrefix64) is 332 configured, the length of the prefix must be /96. 334 o When distinct IPv6 multicast address scopes [RFC7346] are required 335 to preserve the scope when translating IPv4 multicast addresses 336 (Section 8 of [RFC2365]), each scope is configured as a separate 337 OPTION_V6_PREFIX64. How DHCP servers are configured to separate 338 multicast Prefix64 per scope is implementation-specific and not 339 covered by this document. 341 o When scope preservation is not required, only one instance of 342 OPTION_V6_PREFIX64 is configured. 344 Authors' Addresses 346 Mohamed Boucadair 347 Orange 348 Rennes 35000 349 France 351 Email: mohamed.boucadair@orange.com 353 Jacni Qin 354 Cisco 355 P.R. China 357 Email: jacni@jacni.com 359 Tina Tsou 360 Philips Lighting 361 United States of America 363 Email: tina.tsou@philips.com 365 Xiaohong Deng 366 The University of New South Wales 367 Sydney NSW 2052 368 Australia 370 Email: dxhbupt@gmail.com