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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 Operations (v6ops) J. Palet Martinez 3 Internet-Draft The IPv6 Company 4 Intended status: Informational H. M.-H. Liu 5 Expires: September 3, 2018 D-Link Systems, Inc. 6 March 2, 2018 8 Transition Requirements for IPv6 Customer Edge Routers to support IPv4 9 as a Service 10 draft-palet-v6ops-transition-ipv4aas-00 12 Abstract 14 This document specifies the transition requirements for an IPv6 15 Customer Edge (CE) router, either provided by the service provider or 16 thru the retail market. 18 Specifically, this document extends the "Basic Requirements for IPv6 19 Customer Edge Routers" ([RFC7084]) in order to allow the provisioning 20 of IPv6 transition services for the support of IPv4 as a Service 21 (IPv4aaS) by means of new transition mechanisms, which where not 22 available at the time [RFC7084] was published. The document only 23 covers transition technologies for delivering IPv4 in IPv6-only 24 access networks, commonly called IPv4 "as-a-service" (IPv4aaS), as 25 required in a world where IPv4 addresses are no longer available, so 26 hosts in the customer LANs with IPv4-only or IPv6-only applications 27 or devices, requiring to communicate with IPv4-only services at the 28 Internet, are still able to do so. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on September 3, 2018. 47 Copyright Notice 49 Copyright (c) 2018 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 4 68 4. End-User Network Architecture . . . . . . . . . . . . . . . . 6 69 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 9 70 5.1. General Requirements . . . . . . . . . . . . . . . . . . 9 71 5.2. LAN-Side Configuration . . . . . . . . . . . . . . . . . 9 72 5.3. Transition Technologies Support for IPv4 Service 73 Continuity (IPv4 as a Service - IPv4aaS) . . . . . 9 74 5.3.1. 464XLAT . . . . . . . . . . . . . . . . . . . . . . . 10 75 5.3.2. Lightweight 4over6 (lw4o6) . . . . . . . . . . . . . 10 76 5.3.3. MAP-E . . . . . . . . . . . . . . . . . . . . . . . . 11 77 5.3.4. MAP-T . . . . . . . . . . . . . . . . . . . . . . . . 11 78 6. IPv4 Multicast Support . . . . . . . . . . . . . . . . . . . 12 79 7. Code Considerations . . . . . . . . . . . . . . . . . . . . . 12 80 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 81 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 82 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 83 10.1. Normative References . . . . . . . . . . . . . . . . . . 13 84 10.2. Informative References . . . . . . . . . . . . . . . . . 15 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 87 1. Introduction 89 This document defines basic IPv6 transition features for a 90 residential or small-office router, referred to as an "IPv6 91 Transition CE router with IPv4aaS support", in order to establish an 92 industry baseline for transition features to be implemented on such a 93 router. 95 These routers are based on "Basic Requirements for IPv6 Customer Edge 96 Routers" ([RFC7084]), so the scope of this documents is to ensure the 97 IPv4 "service continuity" support, in the LAN side and the access to 98 IPv4-only Internet services from an IPv6-only access WAN even from 99 IPv6-only applications or devices in the LAN side. 101 This document covers the IP transition technologies required when 102 ISPs have already an IPv6-only access network, which is becoming a 103 common situation in a world where IPv4 addresses are no longer 104 available, so the service providers need to provision IPv6-only WAN 105 access, while at the same time ensuring that both IPv4-only and 106 IPv6-only devices or applications in the customer LANs, can still 107 reach IPv4-only devices or applications in Internet, which still 108 don't have IPv6 support. 110 This document specifies the transition mechanisms to be supported by 111 an IPv6 transition CE router, and relevant provisioning or 112 configuration information differences from [RFC7084]. 114 This document is not a recommendation for service providers to use 115 any specific transition mechanism. 117 Automatic provisioning of more complex topology than a single router 118 with multiple LAN interfaces may be handled by means of HNCP 119 ([RFC7788]), which is out of the scope of this document. 121 The CE vendors need to consider that the situation of lack of IPv4 122 addresses and the IPv6 deployment, is a global issue, so the CEs 123 fulfilling the requirements of this document aren't only those 124 provided by the service providers to the customers, but also the 125 customers may need to replace existing ones by themselves thru the 126 retail market. 128 1.1. Requirements Language 130 Take careful note: Unlike other IETF documents, the key words "MUST", 131 "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", 132 "RECOMMENDED", "MAY", and "OPTIONAL" in this document are not used as 133 described in RFC 2119 [RFC2119]. This document uses these keywords 134 not strictly for the purpose of interoperability, but rather for the 135 purpose of establishing industry-common baseline functionality. As 136 such, the document points to several other specifications (preferable 137 in RFC or stable form) to provide additional guidance to implementers 138 regarding any protocol implementation required to produce a 139 successful IPv6 Transition CE router that interoperates successfully 140 with a particular subset of currently deploying and planned common 141 IPv6 access networks. 143 2. Terminology 145 This document uses the same terminology as in [RFC7084], with two 146 minor clarifications. 148 The term "IPv6 transition Customer Edge Router with IPv4aaS" 149 (shortened as "IPv6 transition CE") is defined as an "IPv6 Customer 150 Edge Router" that provides transition support to allow IPv4-IPv6 151 coexistence either beyond the WAN, in the LAN or both. 153 The "WAN Interface" term used across this document, means that can 154 also support link technologies based in Internet-layer (or higher- 155 layers) "tunnels", such as IPv4-in-IPv6 tunnels. 157 3. Usage Scenarios 159 The situation before described, where there is ongoing IPv6 160 deployment and lack of IPv4 addresses, is not happening at the same 161 pace at every country, and even within every country, every ISP. For 162 different technical, financial, commercial/marketing and socio- 163 economical reasons, each network is transitioning at their own pace, 164 and nobody has a magic crystal ball, to make a guess. 166 Different studies also show that this is a changing situation, 167 because in a single country, may be not all operators provide IPv6 168 support, and customer churn implies that the same customers at some 169 point may have IPv6 service and may not have it, if changing ISP, and 170 viceversa. 172 So it is clear that, to cover all those evolving situations, it is 173 required an IPv6 transition CE which, at least from the perspective 174 of the transition support, can keep accommodating to those changes, 175 as it may be or not provided by the service provider. Even may be a 176 point when, having one working seamlessly among different operators 177 means lower cost for changing them, and so, increase and facilitate 178 competition. 180 Moreover, because some services will remain as IPv4-only for an 181 undetermined time and some service providers may also delay their 182 IPv6 support, again for an undetermined period of time, there is an 183 uncertainty about how much time there will be a percentage of IPv4 184 traffic between end-users and end-services, that definitively needs 185 to be "serviced", so there will be a need to provide CEs with support 186 "IPv4 as a Service" for some time. 188 This document is consequently, based on those premises, in order to 189 ensure the continued transition from networks that today may provide 190 access with dual-stack or IPv6-in-IPv4, as described in [RFC7084], 191 and as an "extension" to it, evolving to an IPv6-only access with 192 IPv4-as-a-Service. 194 Considering that situation and different possible usage cases, the 195 IPv6 Transition CE router described in this document is expected to 196 be used typically, in any of the following scenarios: 198 1. Residential/household users. Common usage is any kind of 199 Internet access (web, email, streaming, online gaming, etc.). 201 2. Residential with Small Office/Home Office (SOHO). Same usage as 202 for the first scenario. 204 3. Small Office/Home Office (SOHO). Same usage as for the first 205 scenario. 207 4. Small and Medium Enterprise (SME). Same usage as for the first 208 scenario. 210 5. Residential/household with advanced requirements. Same basic 211 usage as for the first scenario, however there may be 212 requirements for exporting services to the WAN (IP cameras, web, 213 DNS, email, VPN, etc.). 215 6. Small and Medium Enterprise (SME) with advanced requirements. 216 Same basic usage as for the first scenario, however there may be 217 requirements for exporting services to the WAN (IP cameras, web, 218 DNS, email, VPN, etc.). 220 The above list is not intended to be comprehensive of all the 221 possible usage scenarios, just the main ones. In fact, combinations 222 of the above usages are also possible, for example a residential with 223 SOHO and advanced requirements, as well as situations where the same 224 CE is used at different times in different scenarios or even 225 different services providers that may use a different transition 226 mechanism. 228 The mechanisms for exporting IPv6 services are commonly "naturally" 229 available in any IPv6 router, as when using GUA, unless they are 230 blocked by firewall rules, which may require some manual 231 configuration by means of a GUI and/or CLI. 233 However, in the case of IPv4, because the usage of private addresses 234 and NAT, it typically requires some degree of manual configuration 235 such as setting up a DMZ, virtual servers, or port/protocol 236 forwarding. In general, CE routers already provide GUI and/or CLI to 237 manually configure them, or the possibility to setup the CE in bridge 238 mode, so another CE behind it, takes care of that. It is out of the 239 scope of this document the definition of any requirements for that. 241 The main difference for an IPv6 Transition CE router to support one 242 or several of the above indicated scenarios, is related to the packet 243 processing capabilities, performance, even other details such as the 244 number of WAN/LAN interfaces, their maximum speed, memory for keeping 245 tables or tracking connections, etc. So, it is out of the scope of 246 this document to classify them. 248 For example, an SME may have just 10 employees (micro-SME), which 249 commonly will be considered same as a SOHO, but a small SME can have 250 up to 50 employees, or 250 for a medium one. Depending on the IPv6 251 Transition CE router capabilities or even how it is being configured 252 (for instance, using SLAAC or DHCPv6), it may support even a higher 253 number of employees if the traffic in the LANs is low, or switched by 254 another device(s), or the WAN bandwidth requirements are low, etc. 255 The actual bandwidth capabilities of access with technologies such as 256 FTTH, cable and even 3GPP/LTE, allows the support of such usages, and 257 indeed, is a very common situation that access networks and the IPv6 258 Transition CE provided by the service provider are the same for SMEs 259 and residential users. 261 There is also no difference in terms of who actually provides the 262 IPv6 Transition CE router. In most of the cases is the service 263 provider, and in fact is responsible, typically, of provisioning/ 264 managing at least the WAN side. However, commonly the user has 265 access to configure the LAN interfaces, firewall, DMZ, and many other 266 aspects. In fact, in many cases, the user must supply, or at least 267 can replace the IPv6 Transition CE router, which makes even more 268 relevant that all the IPv6 Transition CE routers, support the same 269 requirements defined in this document, despite if they are provided 270 directly by the service provider or acquired thru the retail market. 272 The IPv6 Transition CE router described in this document is not 273 intended for usage in other scenarios such as bigger Enterprises, 274 Data Centers, Content Providers, etc. So, even if the documented 275 requirements meet their needs, may have additional requirements, 276 which are out of the scope of this document. 278 4. End-User Network Architecture 280 According to the descriptions in the precedent sections, an end-user 281 network will likely support both IPv4 and IPv6. It is not expected 282 that an end user will change their existing network topology with the 283 introduction of IPv6. There are some differences in how IPv6 works 284 and is provisioned; these differences have implications for the 285 network architecture. 287 A typical IPv4 end-user network consists of a "plug and play" router 288 with NAT functionality and a single link behind it, connected to the 289 service provider network. 291 From the perspective of an "IPv4 user" behind an IPv6 transition 292 Customer Edge Router with IPv4aaS, this doesn't change. 294 However, while a typical IPv4 NAT deployment by default blocks all 295 incoming connections and may allow opening of ports using a Universal 296 Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some 297 other firewall control protocol, in the case of an IPv6-only access, 298 the latest may not be feasible depending on specific transition 299 mechanism details. PCP (Port Control Protocol, [RFC6887]) may be an 300 alternative solution, as well. 302 Another consequence of using IPv4 private address space in the end- 303 user network is that it provides stable addressing; that is, it never 304 changes even when you change service providers, and the addresses are 305 always there even when the WAN interface is down or the customer edge 306 router has not yet been provisioned. In the case of an IPv6-only 307 access, there is no change on that if the transition mechanism keeps 308 running the NAT interface towards the LAN side. 310 Many existing routers support dynamic routing (which learns routes 311 from other routers), and advanced end-users can build arbitrary, 312 complex networks using manual configuration of address prefixes 313 combined with a dynamic routing protocol. Once again, this is true 314 for both, IPv4 and IPv6. 316 In general, the end-user network architecture for IPv6 should provide 317 equivalent or better capabilities and functionality than the current 318 IPv4 architecture. 320 The end-user network is a stub network, in the sense that is not 321 providing transit to other external networks. However HNCP 322 ([RFC7788]) allows support for automatic provisioning of downstream 323 routers. Figure 1 illustrates the model topology for the end-user 324 network. 326 +---------------+ \ 327 | Service | \ 328 | Provider | | Service 329 | Router | | Provider 330 +-------+-------+ | Network 331 | / 332 | Customer / 333 | Internet Connection / 334 | 335 +------+--------+ \ 336 | IPv6 | \ 337 | Customer Edge | \ 338 | Router | / 339 +---+-------+---+ / 340 Network A | | Network B | 341 ---+----------------+-+- --+---+-------------+-- | 342 | | | | \ 343 +---+------+ | +----+-----+ +-----+----+ \ 344 |IPv6 Host | | | IPv4 Host| |IPv4/IPv6 | / 345 | | | | | | Host | / 346 +----------+ | +----------+ +----------+ / 347 | | 348 +------+--------+ | End-User 349 | IPv6 | | Network(s) 350 | Router | \ 351 +------+--------+ \ 352 Network C | \ 353 ---+-------------+--+--- | 354 | | | 355 +---+------+ +----+-----+ | 356 |IPv6 Host | |IPv6 Host | / 357 | | | | / 358 +----------+ +----------+ / 360 Figure 1: An Example of a Typical End-User Network 362 This architecture describes the: 364 o Basic capabilities of an IPv6 Transition CE router 366 o Provisioning of the WAN interface connecting to the service 367 provider 369 o Provisioning of the LAN interfaces 371 The IPv6 Transition CE router may be manually configured in an 372 arbitrary topology with a dynamic routing protocol or using HNCP 373 ([RFC7788]). Automatic provisioning and configuration is described 374 for a single IPv6 Transition CE router only. 376 5. Requirements 378 The IPv6 Transition CE router must comply with all the requirements 379 stated in [RFC7084]. 381 5.1. General Requirements 383 A new general requirement is added: 385 G-6 The IPv6-only CE router MUST comply with [RFC7608]. 387 5.2. LAN-Side Configuration 389 A new LAN requirement is: 391 L-15 The IPv6 CE router SHOULD implement a DNS proxy as described in 392 [RFC5625]. 394 5.3. Transition Technologies Support for IPv4 Service Continuity (IPv4 395 as a Service - IPv4aaS) 397 The main target of this document is the support of IPv6-only WAN 398 access, and while needed, the support of IPv4-only devices and 399 applications in the customers LANs, in one side of the picture. In 400 the other side, some remote services may stay IPv4-only, so a 401 solution is also required for both the IPv4-only and the IPv6-only 402 devices inside the CE are able to reach the IPv4-only services. 403 Consequently, transition technologies to resolve both sides of the 404 picture are considered. 406 In order to seamlessly provide the IPv4 Service Continuity in 407 Customer LANs, allowing an automated IPv6 transition mechanism 408 provisioning, a new general transition requirement is added. 410 General transition requirement: 412 TRANS-1: The IPv6 Transition CE router MUST support the DHCPv6 S46 413 priority option described in [RFC8026] if more than one S46 414 mechanisms is supported. 416 The following sections describe the requirements for supporting 417 additional transition mechanisms not included in [RFC7084]. 419 5.3.1. 464XLAT 421 464XLAT [RFC6877] is a technique to provide IPv4 access service to 422 IPv6-only edge networks without encapsulation. 424 The IPv6 Transition CE router SHOULD support CLAT functionality. If 425 464XLAT is supported, it MUST be implemented according to [RFC6877]. 426 The following CE Requirements also apply: 428 464XLAT requirements: 430 464XLAT-1: The IPv6 Transition CE router MUST verify if the WAN link 431 supports native IPv4, and if that's not available, MUST 432 enable the CLAT (in order to automatically configure 433 [RFC6877]), unless there is a match with a valid 434 OPTION_S46_PRIORITY (following section 1.4 of [RFC8026]), 435 which will allow configuring any of the other transition 436 mechanisms. 438 464XLAT-2: The IPv6 Transition CE router MUST perform IPv4 Network 439 Address Translation (NAT) on IPv4 traffic translated 440 using the CLAT, unless a dedicated /64 prefix has been 441 acquired using DHCPv6-PD [RFC3633]. 443 464XLAT-3: The IPv6 Transition CE router MUST implement [RFC7050] in 444 order to discover the PLAT-side translation IPv4 and IPv6 445 prefix(es)/suffix(es). In environments with PCP support, 446 the IPv6 Transition CE SHOULD follow [RFC7225] to learn 447 the PLAT-side translation IPv4 and IPv6 448 prefix(es)/suffix(es) used by an upstream PCP-controlled 449 NAT64 device. 451 5.3.2. Lightweight 4over6 (lw4o6) 453 Lw4o6 [RFC7596] specifies an extension to DS-Lite, which moves the 454 NAPT function from the DS-Lite tunnel concentrator to the tunnel 455 client located in the IPv6 Transition CE router, removing the 456 requirement for a CGN function in the tunnel concentrator and 457 reducing the amount of centralized state. 459 The IPv6 Transition CE router SHOULD implement lw4o6 functionality. 460 If DS-Lite is implemented, lw4o6 MUST be supported as well. If lw4o6 461 is supported, it MUST be implemented according to [RFC7596]. This 462 document takes no position on simultaneous operation of lw4o6 and 463 native IPv4. The following IPv6 Transition CE router Requirements 464 also apply: 466 Lw4o6 requirements: 468 LW4O6-1: The IPv6 Transition CE router MUST support configuration of 469 lw4o6 via the lw4o6 DHCPv6 options [RFC7598]. The IPv6 470 Transition CE router MAY use other mechanisms to configure 471 lw4o6 parameters. Such mechanisms are outside the scope of 472 this document. 474 LW4O6-2: The IPv6 Transition CE router MUST support the DHCPv4-over- 475 DHCPv6 (DHCP 4o6) transport described in [RFC7341]. 477 LW4O6-3: The IPv6 Transition CE router MAY support Dynamic 478 Allocation of Shared IPv4 Addresses as described in 479 [RFC7618]. 481 5.3.3. MAP-E 483 MAP-E [RFC7597] is a mechanism for transporting IPv4 packets across 484 an IPv6 network using IP encapsulation, including a generic mechanism 485 for mapping between IPv6 addresses and IPv4 addresses as well as 486 transport-layer ports. 488 The IPv6 Transition CE router SHOULD support MAP-E functionality. If 489 MAP-E is supported, it MUST be implemented according to [RFC7597]. 490 The following CE Requirements also apply: 492 MAP-E requirements: 494 MAPE-1: The IPv6 Transition CE router MUST support configuration of 495 MAP-E via the MAP-E DHCPv6 options [RFC7598]. The IPv6 496 Transition CE router MAY use other mechanisms to configure 497 MAP-E parameters. Such mechanisms are outside the scope of 498 this document. 500 5.3.4. MAP-T 502 MAP-T [RFC7599] is a mechanism similar to MAP-E, differing from it in 503 that MAP-T uses IPv4-IPv6 translation, rather than encapsulation, as 504 the form of IPv6 domain transport. 506 The IPv6 Transition CE router SHOULD support MAP-T functionality. If 507 MAP-T is supported, it MUST be implemented according to [RFC7599]. 508 The following IPv6 Transition CE Requirements also apply: 510 MAP-T requirements: 512 MAPT-1: The CE router MUST support configuration of MAP-T via the 513 MAP-T DHCPv6 options [RFC7598]. The IPv6 Transition CE 514 router MAY use other mechanisms to configure MAP-T 515 parameters. Such mechanisms are outside the scope of this 516 document. 518 6. IPv4 Multicast Support 520 Actual deployments support IPv4 multicast for services such as IPTV. 521 In the transition phase it is expected that multicast services will 522 still be provided using IPv4 to the customer LANs. 524 In order to support the delivery of IPv4 multicast services to IPv4 525 clients over an IPv6 multicast network, the IPv6 Transition CE router 526 SHOULD support [RFC8114] and [RFC8115]. 528 7. Code Considerations 530 One of the apparent main issues for vendors to include new 531 functionalities, such as support for new transition mechanisms, is 532 the lack of space in the flash (or equivalent) memory. However, it 533 has been confirmed from existing open source implementations 534 (OpenWRT/LEDE, Linux, others), that adding the support for the new 535 transitions mechanisms, requires around 10-12 Kbytes (because most of 536 the code base is shared among several transition mechanisms already 537 supported by [RFC7084]), as a single data plane is common to all 538 them, which typically means about 0,15% of the existing code size in 539 popular CEs already in the market. 541 It is also clear that the new requirements don't have extra cost in 542 terms of RAM memory, neither other hardware requirements such as more 543 powerful CPUs. 545 The other issue seems to be the cost of developing the code for those 546 new functionalities. However at the time of writing this document, 547 it has been confirmed that there are several open source versions of 548 the required code for supporting the new transition mechanisms, and 549 even several vendors already have implementations and provide it to 550 ISPs, so the development cost is negligent, and only integration and 551 testing cost may become a minor issue. 553 8. Security Considerations 555 The IPv6 Transition CE router must comply with the Security 556 Considerations as stated in [RFC7084]. 558 9. Acknowledgements 560 Thanks to James Woodyatt, Mohamed Boucadair, Masanobu Kawashima, 561 Mikael Abrahamsson, Barbara Stark, Ole Troan and Brian Carpenter for 562 their review and comments in previous versions of this document. 564 10. References 566 10.1. Normative References 568 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 569 Requirement Levels", BCP 14, RFC 2119, 570 DOI 10.17487/RFC2119, March 1997, 571 . 573 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 574 RFC 2131, DOI 10.17487/RFC2131, March 1997, 575 . 577 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 578 Host Configuration Protocol (DHCP) version 6", RFC 3633, 579 DOI 10.17487/RFC3633, December 2003, 580 . 582 [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed 583 Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March 584 2004, . 586 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 587 for IPv6 Hosts and Routers", RFC 4213, 588 DOI 10.17487/RFC4213, October 2005, 589 . 591 [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", 592 BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009, 593 . 595 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 596 Infrastructures (6rd) -- Protocol Specification", 597 RFC 5969, DOI 10.17487/RFC5969, August 2010, 598 . 600 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 601 Stack Lite Broadband Deployments Following IPv4 602 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, 603 . 605 [RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration 606 Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite", 607 RFC 6334, DOI 10.17487/RFC6334, August 2011, 608 . 610 [RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT: 611 Combination of Stateful and Stateless Translation", 612 RFC 6877, DOI 10.17487/RFC6877, April 2013, 613 . 615 [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and 616 P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, 617 DOI 10.17487/RFC6887, April 2013, 618 . 620 [RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of 621 the IPv6 Prefix Used for IPv6 Address Synthesis", 622 RFC 7050, DOI 10.17487/RFC7050, November 2013, 623 . 625 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 626 Requirements for IPv6 Customer Edge Routers", RFC 7084, 627 DOI 10.17487/RFC7084, November 2013, 628 . 630 [RFC7225] Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the 631 Port Control Protocol (PCP)", RFC 7225, 632 DOI 10.17487/RFC7225, May 2014, 633 . 635 [RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I. 636 Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", 637 RFC 7341, DOI 10.17487/RFC7341, August 2014, 638 . 640 [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. 641 Farrer, "Lightweight 4over6: An Extension to the Dual- 642 Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, 643 July 2015, . 645 [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., 646 Murakami, T., and T. Taylor, Ed., "Mapping of Address and 647 Port with Encapsulation (MAP-E)", RFC 7597, 648 DOI 10.17487/RFC7597, July 2015, 649 . 651 [RFC7598] Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec, 652 W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for 653 Configuration of Softwire Address and Port-Mapped 654 Clients", RFC 7598, DOI 10.17487/RFC7598, July 2015, 655 . 657 [RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S., 658 and T. Murakami, "Mapping of Address and Port using 659 Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July 660 2015, . 662 [RFC7608] Boucadair, M., Petrescu, A., and F. Baker, "IPv6 Prefix 663 Length Recommendation for Forwarding", BCP 198, RFC 7608, 664 DOI 10.17487/RFC7608, July 2015, 665 . 667 [RFC7618] Cui, Y., Sun, Q., Farrer, I., Lee, Y., Sun, Q., and M. 668 Boucadair, "Dynamic Allocation of Shared IPv4 Addresses", 669 RFC 7618, DOI 10.17487/RFC7618, August 2015, 670 . 672 [RFC8026] Boucadair, M. and I. Farrer, "Unified IPv4-in-IPv6 673 Softwire Customer Premises Equipment (CPE): A DHCPv6-Based 674 Prioritization Mechanism", RFC 8026, DOI 10.17487/RFC8026, 675 November 2016, . 677 [RFC8114] Boucadair, M., Qin, C., Jacquenet, C., Lee, Y., and Q. 678 Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients 679 over an IPv6 Multicast Network", RFC 8114, 680 DOI 10.17487/RFC8114, March 2017, 681 . 683 [RFC8115] Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6 684 Option for IPv4-Embedded Multicast and Unicast IPv6 685 Prefixes", RFC 8115, DOI 10.17487/RFC8115, March 2017, 686 . 688 10.2. Informative References 690 [RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking 691 Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April 692 2016, . 694 [UPnP-IGD] 695 UPnP Forum, "InternetGatewayDevice:2 Device Template 696 Version 1.01", December 2010, 697 . 699 Authors' Addresses 700 Jordi Palet Martinez 701 The IPv6 Company 702 Molino de la Navata, 75 703 La Navata - Galapagar, Madrid 28420 704 Spain 706 EMail: jordi.palet@theipv6company.com 707 URI: http://www.theipv6company.com/ 709 Hans M.-H. Liu 710 D-Link Systems, Inc. 711 17595 Mount Herrmann St. 712 Fountain Valley, California 92708 713 US 715 EMail: hans.liu@dlinkcorp.com 716 URI: http://www.dlink.com/