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Please replace those with straight textual mentions of the documents in question. == The 'Updates: ' line in the draft header should list only the _numbers_ of the RFCs which will be updated by this document (if approved); it should not include the word 'RFC' in the list. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (November 4, 2015) is 3068 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) == Unused Reference: 'I-D.farrer-softwire-br-multiendpoints' is defined on line 310, but no explicit reference was found in the text == Unused Reference: 'RFC2131' is defined on line 315, but no explicit reference was found in the text -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Softwire WG I. Farrer 3 Internet-Draft Deutsche Telekom AG 4 Updates: RFC7568 (if approved) Q. Sun 5 Intended status: Standards Track Y. Cui 6 Expires: May 7, 2016 Tsinghua University 7 November 4, 2015 9 DHCPv4 over DHCPv6 Source Address Option 10 draft-fsc-softwire-dhcp4o6-saddr-opt-04 12 Abstract 14 DHCPv4 over DHCPv6 [RFC7341] describes a mechanism for dynamically 15 configuring IPv4 over an IPv6-only network. For DHCPv4 over DHCPv6 16 to function with some IPv4-over-IPv6 softwire mechanisms and 17 deployment scenarios, the operator must learn the /128 IPv6 address 18 that the client will use as the source of IPv4-in-IPv6 tunnel. This 19 address, in conjunction with the IPv4 address and the Port Set ID 20 allocated to the DHCP 4o6 client are used to create a binding table 21 entry in the softwire tunnel concentrator. This memo defines two 22 DHCPv6 options used to communicate the source tunnel IPv6 address 23 between the DHCP 4o6 client and server. It also describes a method 24 for configuring the client with the IPv6 address of the border router 25 so that the softwire can be established. It is designed to work in 26 conjunction with the IPv4 address allocation process. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on May 7, 2016. 45 Copyright Notice 47 Copyright (c) 2015 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 3 64 3. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 65 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 3 66 4.1. Providisioning the BR Address . . . . . . . . . . . . . . 4 67 5. IPv6/IPv4 Binding Message Flow . . . . . . . . . . . . . . . 4 68 6. DHCPv6 Options . . . . . . . . . . . . . . . . . . . . . . . 6 69 6.1. DHCPv4 over DHCPv6 Source Address Hint Option . . . . . . 6 70 6.2. DHCPv4 over DHCPv6 Source Address Option . . . . . . . . 6 71 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 73 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 74 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 75 10.1. Normative References . . . . . . . . . . . . . . . . . . 7 76 10.2. Informative References . . . . . . . . . . . . . . . . . 7 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 79 1. Introduction 81 Deterministic IPv4-over-IPv6 transition technologies require that 82 elements are pre-configured with binding rules for routing traffic to 83 clients. This places a constraint on the location of the client's 84 tunnel endpoint: The tunnel endpoint has to be a pre-determined 85 prefix which is usually be configured on the home gateway device. 86 [RFC7597] describes a DHCPv6 based mechanism for provisioning such 87 deterministic softwires. 89 A dynamic provisioning model, such as using DHCPv4 over DHCPv6 90 [RFC7341] allows much more flexibility in the location of the IPv4- 91 over-IPv6 tunnel endpoint, as the IPv6 address is dynamically 92 signalled back to the service provider so that the corresponding 93 tunnel configuration in the border router (BR) can be created. The 94 DHCP 4o6 client and tunnel client could be run on end devices 95 attached to any routable IPv6 prefix allocated to an end-user, 96 located anywhere within an arbitrary home network topology. Dynamic 97 allocation also helps to optimize IPv4 resource usage as only clients 98 which are currently active are allocated IPv4 addresses. 100 This document describes a mechanism for provisioning dynamically 101 created softwires using DHCPv4 over DHCPv4 (DHCP 4o6), including 102 proivisioning the client with the address of the softwire border 103 router (BR) and informing the service provider of client's binding 104 between the dynamically allocated IPv4 address and Port Set ID and 105 the IPv6 address that the softwire Initiator will use for accessing 106 IPv4-over-IPv6 services. 108 It is used with DHCP 4o6 message flows to communicate the binding 109 over the IPv6-only network. The service provider can then use this 110 binding information to provision other functional elements in their 111 network accordingly, e.g. using the client's binding information to 112 synchronise the binding table in the border router. 114 2. Applicability 116 The mechanism described in this document is only suitable for use for 117 provisioning softwire clients via DHCP 4o6. The options described 118 here are only applicable within the DHCP 4o6 message exchange 119 process. Current mechanisms suitable for extending to incorporate 120 DHCPv4 over DHCPv6 with dynamic IPv4 address leasing include 121 [RFC7597] and [RFC7596]. 123 3. Requirements Language 125 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 126 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 127 document are to be interpreted as described in RFC 2119 [RFC2119]. 129 4. Solution Overview 131 The solution in this document is intended for the dynamic 132 establishment of IPv4-over-IPv6 softwires. DHCP 4o6 [RFC7341] 133 supports dynamically allocating (shared) IPv4 address. For a 134 softwire to be successfully created, the IPv4 address has to be 135 linked to the client's IPv6 tunnel source address. Within this 136 process, the DHCP 4o6 client uses a DHCPv6 option to signal its 137 tunnel source IPv6 address to the DHCP 4o6 server so that the 138 operator's provisioning system can create the binding and configure 139 the tunnel concentrator accordingly. 141 Two new DHCPv6 options are defined in this memo: 142 OPTION_DHCP4O6_SADDR_HINT and OPTION_DHCP4O6_SADDR. They are 143 intended to be used alongside the normal DHCPv4 IPv4 address 144 allocation message flow in the context of DHCPv4 over DHCPv6 145 [RFC7341]. If a DHCP 4o6 client supports this mechanism, it MUST 146 include the code of OPTION_DHCP4O6_SADDR_HINT in the Option Request 147 Option (ORO) [RFC3315] when requesting IPv4 configuration through 148 DHCP 4o6. 150 The communication of parameters between the client and server is a 151 two-way process: OPTION_DHCP4O6_SADDR_HINT is optionally used by the 152 DHCP 4o6 server to indicate to the client a preferred IPv6 prefix for 153 binding the received IPv4 configuration and sourcing tunnel traffic. 154 This may be necessary if there are multiple IPv6 prefixes in use in 155 the customer network (e.g. ULAs), or if the specific IPv4-over-IPv6 156 transition mechanism requires the use of a particular prefix for any 157 reason. When the client has selected an IPv6 address to bind the 158 IPv4 configuration to, it passes the address back to the DHCP 4o6 159 server through OPTION_DHCP4O6_SADDR. 161 4.1. Providisioning the BR Address 163 To configure a softwire, the initiator also requires the IPv6 address 164 of the BR. Section 4.2 of [RFC7598] defines option 90 165 (OPTION_S46_BR) for this purpose, but mandates that the option can 166 only be used when when encapsulated within one of the softwire 167 container options: OPTION_S46_CONT_MAPE, OPTION_S46_CONT_MAPT or 168 OPTION_S46_CONT_LW. From Section 3 of [RFC7598]: 170 "Softwire46 DHCPv6 clients that receive provisioning options that 171 are not encapsulated in container options MUST silently ignore 172 these options." 174 This document updates [RFC7598] to remove this restriction for DHCPv6 175 option 90 (OPTION_S46_BR) allowing it to appear directly within the 176 list of options in the client's ORO request and directly withing 177 subsequent messages sent by the DHCPv6 server. 179 5. IPv6/IPv4 Binding Message Flow 181 The following diagram shows the client/server message flow and how 182 the options defined in this document are used. In each step, the 183 relevant DHCPv4 message is given above the arrow and the relevant 184 options below the arrow. The DHCPv4 messages are encapsulated in 185 DHCPv4-query or DHCPv4-response messages, and those options are 186 included in the 'options' field of the DHCPv4-query or 187 DHCPv4-response message. 189 DHCP 4o6 DHCP 4o6 190 Client Server 191 | DHCPDISCOVER (DHCPv4) | 192 Step 1 |----------------------------------------------------->| 193 | ORO with OPTION_S46_BR, | 194 | OPTION_DHCP4O6_SADDR_HINT(DHCPv6) | 195 | | 196 | DHCPOFFER (DHCPv4) | 197 Step 2 |<-----------------------------------------------------| 198 | OPTION_S46_BR, OPTION_DHCP4O6_SADDR_HINT | 199 | (cipv6-prefix-hint with service provider's | 200 | preferred prefix) (DHCPv6) | 201 | | 202 | DHCPREQUEST (DHCPv4) | 203 Step 3 |----------------------------------------------------->| 204 | OPTION_S46_BR, | 205 | OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with | 206 | client's bound /128 IPv6 address) (DHCPv6) | 207 | | 208 | DHCPACK (DHCPv4) | 209 Step 4 |<-----------------------------------------------------| 210 | OPTION_S46_BR, | 211 | OPTION_DHCP4O6_SADDR (cipv6-bound-prefix with | 212 | client's bound /128 IPv6 prefix) (DHCPv6) | 213 | | 215 IPv6/IPv4 Binding Message Flow 217 A client attempting dynamic softwire configuration includes the 218 option code for OPTION_BR_PREFIX, OPTION_DHCP4O6_SADDR_HINT in the 219 DHCPv6 ORO in all DHCPv4-query messages it sends. 221 When a DHCP 4o6 Server replies with a DHCPOFFER message, it SHOULD 222 include an OPTION_S46_BR. It MAY also include 223 OPTION_DHCP4O6_SADDR_HINT, which is used to indicate a preferred 224 prefix that the client should use to bind IPv4 configuration to. If 225 this option is received, the client MUST perform a longest prefix 226 match between cipv6-prefix-hint and all prefixes/addresses in use on 227 the device. If a match is found, the selected prefix MUST then be 228 used to bind the received IPv4 configuration to. If the client 229 doesn't receive OPTION_DHCP4O6_SADDR_HINT the client can select any 230 valid /128 IPv6 prefix to use. 232 OPTION_DHCP4O6_SADDR is used by the client to inform the DHCP 4o6 233 Server which IPv6 address the IPv4 configuration has been bound to. 234 The client MUST put the selected IPv6 address into this option and 235 include it in the DHCPv4-response message when it sends the 236 DHCPREQUEST message. 238 6. DHCPv6 Options 240 6.1. DHCPv4 over DHCPv6 Source Address Hint Option 242 0 1 2 3 243 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 1 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 | OPTION_DHCP4O6_SADDR_HINT | option-length | 246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 |cipv6-hintlen | | 248 +-+-+-+-+-+-+-+-+ cipv6-prefix-hint . 249 . (variable length) . 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 o option-code: OPTION_DHCP4O6_SADDR_HINT (TBA1) 253 o option-length: 1 + length of cipv6-prefix-hint, specified in 254 bytes. 255 o cipv6-hintlen: 8-bit field expressing the bit mask length of the 256 IPv6 prefix specified in cipv6-prefix-hint. 257 o cipv6-prefix-hint: The IPv6 prefix indicating the preferred prefix 258 for the client to bind the received IPv4 configuration to. 260 6.2. DHCPv4 over DHCPv6 Source Address Option 262 The format of DHCPv4 over DHCPv6 Source address option is defined as 263 follows: 265 0 1 2 3 266 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 1 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 268 | OPTION_DHCP4O6_SADDR | option-length | 269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | | 271 + cipv6-src-address + 272 . (128 bits) . 273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 o option-code: OPTION_DHCP4O6_SADDR (TBA2) 276 o option-length: 16. 277 o cipv6-src-address: The IPv6 address that the client has bound the 278 allocated IPv4 configuration to. 280 7. Security Considerations 282 TBD 284 8. IANA Considerations 286 IANA is requested to allocate the DHCPv6 option codes: 287 OPTION_DHCP4O6_SADDR_HINT and OPTION_DHCP4O6_SADDR. 289 9. Acknowledgements 291 The authors would like to thank Ted Lemon and Lishan Li for their 292 contributions. 294 10. References 296 10.1. Normative References 298 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 299 Requirement Levels", BCP 14, RFC 2119, 300 DOI 10.17487/RFC2119, March 1997, 301 . 303 [RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I. 304 Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", 305 RFC 7341, DOI 10.17487/RFC7341, August 2014, 306 . 308 10.2. Informative References 310 [I-D.farrer-softwire-br-multiendpoints] 311 Farrer, I. and Q. Sun, "Multiple BR Tunnel Endpoint 312 Addresses", draft-farrer-softwire-br-multiendpoints-01 313 (work in progress), July 2015. 315 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 316 RFC 2131, DOI 10.17487/RFC2131, March 1997, 317 . 319 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 320 C., and M. Carney, "Dynamic Host Configuration Protocol 321 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 322 2003, . 324 [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. 325 Farrer, "Lightweight 4over6: An Extension to the Dual- 326 Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, 327 July 2015, . 329 [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., 330 Murakami, T., and T. Taylor, Ed., "Mapping of Address and 331 Port with Encapsulation (MAP-E)", RFC 7597, 332 DOI 10.17487/RFC7597, July 2015, 333 . 335 [RFC7598] Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec, 336 W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for 337 Configuration of Softwire Address and Port-Mapped 338 Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015, 339 . 341 Authors' Addresses 343 Ian Farrer 344 Deutsche Telekom AG 345 CTO-ATI, Landgrabenweg 151 346 Bonn, NRW 53227 347 Germany 349 Email: ian.farrer@telekom.de 351 Qi Sun 352 Tsinghua University 353 Beijing 100084 354 P.R. China 356 Phone: +86-10-6278-5822 357 Email: sunqi.csnet.thu@gmail.com 359 Yong Cui 360 Tsinghua University 361 Beijing 100084 362 P.R. China 364 Phone: +86-10-6260-3059 365 Email: yong@csnet1.cs.tsinghua.edu.cn