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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) == Outdated reference: A later version (-18) exists of draft-ietf-softwire-dslite-multicast-12 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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: December 15, 2016 Cisco 6 T. Tsou 7 Philips Lighting 8 X. Deng 9 The University of New South Wales 10 June 13, 2016 12 DHCPv6 Option for IPv4-Embedded Multicast and Unicast IPv6 Prefixes 13 draft-ietf-softwire-multicast-prefix-option-11 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 December 15, 2016. 39 Copyright Notice 41 Copyright (c) 2016 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. 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. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 64 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 65 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 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_PREFIX64: a multicast PREFIX64 which belongs to the Any-Source 107 Multicast (ASM) range. 109 SSM_PREFIX64: a multicast PREFIX64 which belongs to the Source- 110 Specific Multicast (SSM) [RFC4607]) range. 112 U_PREFIX64: a unicast PREFIX64 for building the IPv4-embedded IPv6 113 addresses of multicast sources in SSM mode. 115 3. 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_PREFIX64 (Variable) : 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | ssm-length | | 130 +-+-+-+-+-+-+-+-+ : 131 : SSM_PREFIX64 (Variable) : 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | unicast-length| | 134 +-+-+-+-+-+-+-+-+ : 135 : U_PREFIX64 (Variable) : 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 Figure 1: DHCPv6 Option Format for PREFIX64 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 PREFIX64 option. 146 asm-length: the prefix-length for the ASM IPv4-embedded prefix, as 147 an 8-bit unsigned integer (0 to 128). This field represents the 148 number of valid leading bits in the prefix. 150 ASM_PREFIX64: 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. It is a variable size field 153 with the length of the field defined by the asm-length field and 154 is rounded up to the nearest octet boundary. In this case, any 155 additional padding bits must be zeroed. The conveyed multicast 156 IPv6 prefix MUST belong to the ASM range. 158 ssm-length: the prefix-length for the SSM IPv4-embedded prefix, as 159 an 8-bit unsigned integer (0 to 128). This field represents the 160 number of valid leading bits in the prefix. 162 SSM_PREFIX64: this field identifies the IPv6 multicast prefix to be 163 used to synthesize the IPv4-embedded IPv6 addresses of the 164 multicast groups in the SSM mode. It is a variable size field 165 with the length of the field defined by the ssm-length field and 166 is rounded up to the nearest octet boundary. In such case any 167 additional padding bits must be zeroed. The conveyed multicast 168 IPv6 prefix MUST belong to the SSM range. 170 unicast-length: the prefix-length for the IPv6 unicast prefix to be 171 used to synthesize the IPv4-embedded IPv6 addresses of the 172 multicast sources, as an 8-bit unsigned integer (0 to 128). This 173 field represents the number of valid leading bits in the prefix. 175 U_PREFIX64: this field identifies the IPv6 unicast prefix to be used 176 in SSM mode for constructing the IPv4-embedded IPv6 addresses 177 representing the IPv4 multicast sources in the IPv6 domain. 178 U_PREFIX64 may also be used to extract the IPv4 address from the 179 received multicast data flows. It is a variable size field with 180 the length of the field defined by the unicast-length field and is 181 rounded up to the nearest octet boundary. In this case, any 182 additional padding bits must be zeroed. The address mapping MUST 183 follow the guidelines documented in [RFC6052]. 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 documented in 190 Section 6 of [RFC7051]. 192 4. Configuration Guidelines for the Server 194 DHCP servers supporting OPTION_V6_PREFIX64 should be configured with 195 U_PREFIX64 and at least one multicast PREFIX64 (i.e., ASM_PREFIX64 196 and/or SSM_PREFIX64). 198 When a multicast PREFIX64 (ASM_PREFIX64 or SSM_PREFIX64) is 199 configured, the length of the prefix must be /96. 201 Both ASM_PREFIX64 and SSM_PREFIX64 may be configured and therefore be 202 returned to a requesting DHCP client in the same OPTION_V6_PREFIX64. 203 In particular, if both SSM and ASM modes are supported, ASM_PREFIX64 204 and SSM_PREFIX64 prefixes must be configured. For SSM deployments, 205 both SSM_PREFIX64 and U_PREFIX64 must be configured. 207 When distinct IPv6 multicast address scopes [RFC7346] are required to 208 preserve the scope when translating IPv4 multicast addresses 209 (Section 8 of [RFC2365]), each scope is configured as a separate 210 OPTION_V6_PREFIX64. How DHCP servers are configured to separate 211 multicast PREFIX64 per scope is implementation-specific and not 212 covered by this document. 214 When scope preservation is not required, only one instance of 215 OPTION_V6_PREFIX64 is configured. 217 5. DHCPv6 Client Behavior 219 To retrieve the IPv6 prefixes that will be used to synthesize unicast 220 and multicast IPv4-embedded IPv6 addresses, the DHCPv6 client MUST 221 include OPTION_V6_PREFIX64 in its OPTION_ORO. If the DHCPv6 client 222 receives more than one OPTION_V6_PREFIX64 option from the DHCPv6 223 server: 225 o If each enclosed IPv6 multicast prefix has a distinct scope, the 226 client MUST select the appropriate IPv6 multicast prefix whose 227 scope matches the IPv4 multicast address used to synthesize an 228 IPv4-embedded IPv6 multicast address. 230 o If at least two of the received options convey IPv6 multicast 231 prefixes that have the same scope, the said options MUST be 232 discarded. 234 If asm-length, ssm-length and unicast-length fields are all set to 0, 235 the DHCPv6 client MUST behave as if OPTION_V6_PREFIX64 had not been 236 received in the response received from the DHCPv6 server. 238 If the asm-length field is non-null, the IPv6 prefix identified by 239 ASM_PREFIX64 is used to synthesize IPv4-embedded IPv6 multicast 240 addresses in the ASM range. This is achieved by concatenating the 241 ASM_PREFIX64 and the IPv4 multicast address; the Pv4 multicast 242 address is inserted in the last 32 bits of the IPv4-embedded IPv6 243 multicast address. 245 If the ssm-length field is non-null, the IPv6 prefix identified by 246 SSM_PREFIX64 is used to synthesize IPv4-embedded IPv6 multicast 247 addresses in the SSM range. This is achieved by concatenating the 248 SSM_PREFIX64 and the IPv4 multicast address; the Pv4 multicast 249 address is inserted in the last 32 bits of the IPv4-embedded IPv6 250 multicast address. 252 If the unicast-length field is non-null, the IPv6 prefix identified 253 by U_PREFIX64 is used to synthesize IPv4-embedded IPv6 unicast 254 addresses as specified in [RFC6052]. 256 6. Security Considerations 258 The security considerations documented in [RFC3315] and [RFC6052] are 259 to be considered. 261 7. Acknowledgements 263 Particular thanks to C. Jacquenet, S. Venaas, B. Volz, and T. 264 Taylor for their review. 266 Many thanks to I. Farrer and T. Lemon for the comments. 268 8. IANA Considerations 270 Authors of this document request IANA to assign a new DHCPv6 option 271 code in the registry maintained in http://www.iana.org/assignments/ 272 dhcpv6-parameters: 274 Option Name Value 275 ----------------- ----- 276 OPTION_V6_PREFIX64 TBA 278 9. References 280 9.1. Normative References 282 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 283 Requirement Levels", BCP 14, RFC 2119, 284 DOI 10.17487/RFC2119, March 1997, 285 . 287 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 288 C., and M. Carney, "Dynamic Host Configuration Protocol 289 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 290 2003, . 292 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 293 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 294 . 296 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 297 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 298 DOI 10.17487/RFC6052, October 2010, 299 . 301 9.2. Informative References 303 [I-D.ietf-softwire-dslite-multicast] 304 Qin, J., Boucadair, M., Jacquenet, C., Lee, Y., and Q. 305 Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients 306 over an IPv6 Multicast Network", draft-ietf-softwire- 307 dslite-multicast-12 (work in progress), June 2016. 309 [RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, 310 RFC 2365, DOI 10.17487/RFC2365, July 1998, 311 . 313 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 314 Stack Lite Broadband Deployments Following IPv4 315 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, 316 . 318 [RFC6346] Bush, R., Ed., "The Address plus Port (A+P) Approach to 319 the IPv4 Address Shortage", RFC 6346, 320 DOI 10.17487/RFC6346, August 2011, 321 . 323 [RFC7051] Korhonen, J., Ed. and T. Savolainen, Ed., "Analysis of 324 Solution Proposals for Hosts to Learn NAT64 Prefix", 325 RFC 7051, DOI 10.17487/RFC7051, November 2013, 326 . 328 [RFC7346] Droms, R., "IPv6 Multicast Address Scopes", RFC 7346, 329 DOI 10.17487/RFC7346, August 2014, 330 . 332 Authors' Addresses 334 Mohamed Boucadair 335 Orange 336 Rennes 35000 337 France 339 Email: mohamed.boucadair@orange.com 341 Jacni Qin 342 Cisco 343 China 345 Email: jacni@jacni.com 347 Tina Tsou 348 Philips Lighting 350 Email: tina.tsou@philips.com 352 Xiaohong Deng 353 The University of New South Wales 354 Sydney NSW 2052 355 Australia 357 Email: dxhbupt@gmail.com