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Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 6145 (Obsoleted by RFC 7915) == Outdated reference: A later version (-17) exists of draft-ietf-behave-nat64-discovery-heuristic-11 -- Obsolete informational reference (is this intentional?): RFC 3633 (Obsoleted by RFC 8415) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force M. Mawatari 3 Internet-Draft Japan Internet Exchange Co.,Ltd. 4 Intended status: BCP M. Kawashima 5 Expires: March 22, 2013 NEC AccessTechnica, Ltd. 6 C. Byrne 7 T-Mobile USA 8 September 18, 2012 10 464XLAT: Combination of Stateful and Stateless Translation 11 draft-ietf-v6ops-464xlat-08 13 Abstract 15 This document describes an architecture (464XLAT) for providing 16 limited IPv4 connectivity across an IPv6-only network by combining 17 existing and well-known stateful protocol translation RFC 6146 in the 18 core and stateless protocol translation RFC 6145 at the edge. 464XLAT 19 is a simple and scalable technique to quickly deploy limited IPv4 20 access service to IPv6-only edge networks without encapsulation. 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 March 22, 2013. 39 Copyright Notice 41 Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. BCP Scenario . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 59 4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 5. Motivation and Uniqueness of 464XLAT . . . . . . . . . . . . . 4 61 6. Network Architecture . . . . . . . . . . . . . . . . . . . . . 4 62 6.1. Wireline Network Architecture . . . . . . . . . . . . . . 4 63 6.2. Wireless 3GPP Network Architecture . . . . . . . . . . . . 5 64 7. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 6 65 7.1. Wireline Network Applicability . . . . . . . . . . . . . . 6 66 7.2. Wireless 3GPP Network Applicability . . . . . . . . . . . 7 67 8. Implementation Considerations . . . . . . . . . . . . . . . . 7 68 8.1. IPv6 Address Format . . . . . . . . . . . . . . . . . . . 7 69 8.2. IPv4/IPv6 Address Translation Chart . . . . . . . . . . . 7 70 8.3. IPv6 Prefix Handling . . . . . . . . . . . . . . . . . . . 9 71 8.4. DNS Proxy Implementation . . . . . . . . . . . . . . . . . 9 72 8.5. CLAT in a Gateway . . . . . . . . . . . . . . . . . . . . 9 73 8.6. CLAT to CLAT communications . . . . . . . . . . . . . . . 9 74 9. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 75 9.1. Traffic Engineering . . . . . . . . . . . . . . . . . . . 10 76 9.2. Traffic Treatment Scenarios . . . . . . . . . . . . . . . 10 77 10. Security Considerations . . . . . . . . . . . . . . . . . . . 11 78 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 79 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 80 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 81 13.1. Normative References . . . . . . . . . . . . . . . . . . . 11 82 13.2. Informative References . . . . . . . . . . . . . . . . . . 12 83 Appendix A. Examples of IPv4/IPv6 Address Translation . . . . . . 12 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 86 1. Introduction 88 With the exhaustion of the unallocated IPv4 address pools, it will be 89 difficult for many networks to assign IPv4 addresses to end users. 91 This document describes an IPv4 over IPv6 solution as one of the 92 techniques for IPv4 service extension and encouragement of IPv6 93 deployment. 464XLAT is not a one-for-one replacement of full IPv4 94 functionality. The 464XLAT architecture only supports IPv4 in the 95 client server model, where the server has a global IPv4 address. 96 This means it is not fit for IPv4 peer-to-peer communication or 97 inbound IPv4 connections. 464XLAT builds on IPv6 transport and 98 includes full any-to-any IPv6 communication. 100 The 464XLAT architecture described in this document uses IPv4/IPv6 101 translation standardized in [RFC6145] and [RFC6146]. It does not 102 require DNS64 [RFC6147] since an IPv4 host may simply send IPv4 103 packets, including packets to an IPv4 DNS server, which will be 104 translated on the customer side translator(CLAT) to IPv6 and back to 105 IPv4 on the provider side translator(PLAT). 464XLAT networks may use 106 DNS64 [RFC6147] to enable single stateful translation [RFC6146] 107 instead of 464XLAT double translation where possible. The 464XLAT 108 architecture encourages the IPv6 transition by making IPv4 services 109 reachable across IPv6-only networks and providing IPv6 and IPv4 110 connectivity to single-stack IPv4 or IPv6 servers and peers. 112 2. BCP Scenario 114 This BCP only applies when the following two criteria are present: 116 1. There is an IPv6-only network that uses stateful translation 117 [RFC6146] as the only mechanism for providing IPv4 access. 119 2. There are IPv4-only applications or hosts that must communicate 120 across the IPv6-only network to reach the IPv4 Internet. 122 3. Requirements Language 124 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 125 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 126 document are to be interpreted as described in [RFC2119]. 128 4. Terminology 129 PLAT: PLAT is Provider side translator(XLAT) that complies with 130 [RFC6146]. It translates N:1 global IPv6 addresses to global 131 IPv4 addresses, and vice versa. 133 CLAT: CLAT is Customer side translator(XLAT) that complies with 134 [RFC6145]. It algorithmically translates 1:1 private IPv4 135 addresses to global IPv6 addresses, and vice versa. The CLAT 136 function is applicable to a router or an end-node such as a 137 mobile phone. The CLAT SHOULD perform router function to 138 facilitate packets forwarding through the stateless 139 translation even if it is an end-node. The CLAT as a common 140 home router or wireless 3GPP router is expected to perform 141 gateway functions such as DHCP server and DNS proxy for local 142 clients. The CLAT does not comply with the sentence "Both 143 IPv4-translatable IPv6 addresses and IPv4-converted IPv6 144 addresses SHOULD use the same prefix." that is described on 145 Section 3.3 in [RFC6052] due to using different IPv6 prefixes 146 for CLAT-side and PLAT-side IPv4 addresses. 148 5. Motivation and Uniqueness of 464XLAT 150 1. Minimal IPv4 resource requirements, maximum IPv4 efficiency 151 through statistical multiplexing. 153 2. No new protocols required, quick deployment. 155 3. IPv6-only networks are simpler and therefore less expensive to 156 operate. 158 6. Network Architecture 160 Examples of 464XLAT architectures are shown in the figures in the 161 following sections. 163 Wireline Network Architecture can fit in the situations where there 164 are clients behind the CLAT in the same way regardless of the type of 165 access service, for example FTTH, DOCSIS, or WiFi. 167 Wireless 3GPP Network Architecture fits in the situations where a 168 client terminates the wireless access network and may act as a router 169 with tethered clients. 171 6.1. Wireline Network Architecture 173 The private IPv4 host on this diagram can reach global IPv4 hosts via 174 translation on both CLAT and PLAT. On the other hand, the IPv6 host 175 can reach other IPv6 hosts on the Internet directly without 176 translation. This means that the CPE/CLAT can not only have the 177 function of a CLAT but also the function of an IPv6 native router for 178 native IPv6 traffic. The v4p host behind the CLAT on this diagram 179 has [RFC1918] addresses. 181 +------+ 182 | v6 | 183 | host | 184 +--+---+ 185 | 186 .---+---. 187 / \ 188 / IPv6 \ 189 | Internet | 190 \ / 191 `----+----' 192 | 193 +------+ | .---+---. .------. 194 | v6 +---+ +------+ / \ +------+ / \ 195 | host | | | | / IPv6 \ | | / IPv4 \ 196 +------+ +---+ CLAT +---+ Network +---+ PLAT +---+ Internet | 197 +--------+ | | | \ / | | \ / 198 | v4p/v6 +-+ +------+ `---------' +------+ `----+----' 199 | host | | | 200 +--------+ | +--+---+ 201 +------+ | | v4g | 202 | v4p +---+ | host | 203 | host | | +------+ 204 +------+ | 206 <- v4p -> XLAT <--------- v6 --------> XLAT <- v4g -> 208 v6 : Global IPv6 209 v4p : Private IPv4 210 v4g : Global IPv4 212 Figure 1: Wireline Network Topology 214 6.2. Wireless 3GPP Network Architecture 216 The CLAT function on the User Equipment (UE) provides an [RFC1918] 217 address and IPv4 default route to the local node network stack. The 218 applications on the UE can use the private IPv4 address for reaching 219 global IPv4 hosts via translation on both the CLAT and the PLAT. On 220 the other hand, reaching IPv6 hosts (including host presented via 221 DNS64 [RFC6147]) does not require the CLAT function on the UE. 223 Presenting a private IPv4 network for tethering via NAT44 and 224 stateless translation on the UE is also an application of the CLAT. 226 +------+ 227 | v6 | 228 | host | 229 +--+---+ 230 | 231 .---+---. 232 / \ 233 / IPv6 \ 234 | Internet | 235 \ / 236 UE / Mobile Phone `---------' 237 +----------------------+ | 238 | +----+ | | .---+---. .------. 239 | | v6 +----+ +------+ / \ +------+ / \ 240 | +----+ | | | / IPv6 PDP \ | | / IPv4 \ 241 | +---+ CLAT +---+ Mobile Core +---+ PLAT +--+ Internet | 242 | | | | \ GGSN / | | \ / 243 | | +------+ \ ' +------+ `----+---' 244 | +-----+ | | `-------' | 245 | | v4p +---+ | +--+---+ 246 | +-----+ | | | v4g | 247 +----------------------+ | host | 248 +------+ 250 <- v4p -> XLAT <--------- v6 --------> XLAT <- v4g -> 252 v6 : Global IPv6 253 v4p : Private IPv4 254 v4g : Global IPv4 256 Figure 2: Wireless 3GPP Network Topology 258 7. Applicability 260 7.1. Wireline Network Applicability 262 When an ISP has IPv6 access service and provides 464XLAT, the ISP can 263 provide outgoing IPv4 service to end users across an IPv6 access 264 network. The result is that edge network growth is no longer tightly 265 coupled to the availability of scarce IPv4 addresses. 267 If another ISP operates the PLAT, the edge ISP is only required to 268 deploy an IPv6 access network. All ISPs do not need IPv4 access 269 networks. They can migrate their access network to a simple and 270 highly scalable IPv6-only environment. 272 7.2. Wireless 3GPP Network Applicability 274 At the time of writing, in September 2012, the vast majority of 275 mobile networks are compliant to Pre-Release 9 3GPP standards. In 276 Pre-Release 9 3GPP networks, GSM and UMTS networks must signal and 277 support both IPv4 and IPv6 Packet Data Protocol (PDP) attachments to 278 access IPv4 and IPv6 network destinations [RFC6459]. Since there are 279 two PDPs required to support two address families, this is double the 280 number of PDPs required to support the status quo of one address 281 family, which is IPv4. 283 For the cases of connecting to an IPv4 literal or IPv4 socket that 284 require IPv4 connectivity, the CLAT function on the UE provides a 285 private IPv4 address and IPv4 default route on the host for the 286 applications to reference and bind to. Connections sourced from the 287 IPv4 interface are immediately routed to the CLAT function and passed 288 to the IPv6-only mobile network, destined for the PLAT. In summary, 289 the UE has the CLAT function that does a stateless translation 290 [RFC6145], but only when required by an IPv4-only scenario such as 291 IPv4 literals or IPv4-only sockets. The mobile network has a PLAT 292 that does stateful translation [RFC6146]. 294 464XLAT works with today's existing systems as much as possible. 295 464XLAT is compatible with existing network based deep packet 296 inspection solutions like 3GPP standardized Policy and Charging 297 Control (PCC) [TS.23203]. 299 8. Implementation Considerations 301 8.1. IPv6 Address Format 303 The IPv6 address format in 464XLAT is defined in Section 2.2 of 304 [RFC6052]. 306 8.2. IPv4/IPv6 Address Translation Chart 308 This chart offers a explanation about address translation 309 architecture using combination of stateful translation at the PLAT 310 and stateless translation at the CLAT. The client on this chart is 311 delegated IPv6 prefix from a prefix delegation mechanism such as 312 DHCPv6-PD [RFC3633], therefore it has a dedicated IPv6 prefix for 313 translation. 315 Destination IPv4 address 316 +----------------------------+ 317 | Global IPv4 address | 318 | assigned to IPv4 server | 319 +--------+ +----------------------------+ 320 | IPv4 | Source IPv4 address 321 | server | +----------------------------+ 322 +--------+ | Global IPv4 address | 323 ^ | assigned to IPv4 PLAT pool | 324 | +----------------------------+ 325 +--------+ 326 | PLAT | Stateful XLATE(IPv4:IPv6=1:n) 327 +--------+ 328 ^ 329 | 330 (IPv6 cloud) 331 Destination IPv6 address 332 +--------------------------------------------------------------+ 333 | IPv4-Embedded IPv6 address | 334 | defined in Section 2.2 of RFC6052 | 335 +--------------------------------------------------------------+ 336 Source IPv6 address 337 +--------------------------------------------------------------+ 338 | IPv4-Embedded IPv6 address | 339 | defined in Section 2.2 of RFC6052 | 340 +--------------------------------------------------------------+ 341 (IPv6 cloud) 342 ^ 343 | 344 +--------+ 345 | CLAT | Stateless XLATE(IPv4:IPv6=1:1) 346 +--------+ 347 ^ Destination IPv4 address 348 | +----------------------------+ 349 +--------+ | Global IPv4 address | 350 | IPv4 | | assigned to IPv4 server | 351 | client | +----------------------------+ 352 +--------+ Source IPv4 address 353 +----------------------------+ 354 | Private IPv4 address | 355 | assigned to IPv4 client | 356 +----------------------------+ 358 Case of enabling only stateless XLATE on CLAT 360 8.3. IPv6 Prefix Handling 362 The CLAT SHOULD acquire a dedicated /64 prefix for the purpose of 363 sending and receiving statelessly translated packets. 365 The CLAT MAY discover the PLAT-side translation IPv6 prefix used as a 366 destination of the PLAT via 367 [I-D.ietf-behave-nat64-discovery-heuristic]. In the future some 368 other mechanisms, such as a new DHCPv6 option, will possibly be 369 defined. 371 When a dedicated /64 prefix is not available from DHCPv6-PD 372 [RFC3633], the CLAT MAY perform NAT44 for all IPv4 LAN packets so 373 that all the LAN originated IPv4 packets appear from a single IPv4 374 address and are then statelessly translated to one IPv6 address that 375 is claimed by the CLAT via NDP and defended with DAD. 377 8.4. DNS Proxy Implementation 379 The CLAT SHOULD implement a DNS proxy as defined in [RFC5625]. The 380 case of an IPv4-only node behind the CLAT querying an IPv4 DNS server 381 is undesirable since it requires both stateful and stateless 382 translation for each DNS lookup. The CLAT SHOULD set itself as the 383 DNS server via DHCP or other means and proxy DNS queries for IPv4 and 384 IPv6 LAN clients. Using the CLAT enabled home router or UE as a DNS 385 proxy is a normal consumer gateway function and simplifies the 386 traffic flow so that only IPv6 native queries are made across the 387 access network. The CLAT SHOULD allow for a client to query any DNS 388 server of its choice and bypass the proxy. 390 8.5. CLAT in a Gateway 392 The CLAT is a stateless translation feature which can be implemented 393 in a common home router or mobile phone that has a tethering feature. 394 The router with CLAT function SHOULD provide common router services 395 such as DHCP of [RFC1918] addresses, DHCPv6, and DNS service. 397 8.6. CLAT to CLAT communications 399 While CLAT to CLAT IPv4 communication may work when the client IPv4 400 subnets do not overlap, this traffic flow is out of scope. 464XLAT is 401 a hub and spoke architecture focused on enabling IPv4-only services 402 over IPv6-only networks. 404 9. Deployment Considerations 405 9.1. Traffic Engineering 407 Even if the ISP for end users is different from the PLAT provider 408 (e.g. another ISP), it can implement traffic engineering 409 independently from the PLAT provider. Detailed reasons are below: 411 1. The ISP for end users can figure out IPv4 destination address 412 from translated IPv6 packet header, so it can implement traffic 413 engineering based on IPv4 destination address (e.g. traffic 414 monitoring for each IPv4 destination address, packet filtering 415 for each IPv4 destination address, etc.). The tunneling methods 416 do not have such an advantage, without any deep packet inspection 417 for processing the inner IPv4 packet of the tunnel packet. 419 2. If the ISP for end users can assign an IPv6 prefix greater than 420 /64 to each subscriber, this 464XLAT architecture can separate 421 IPv6 prefix for native IPv6 packets and the XLAT prefixes for 422 IPv4/IPv6 translation packets. Accordingly, it can identify the 423 type of packets ("native IPv6 packets" and "IPv4/IPv6 translation 424 packets"), and implement traffic engineering based on the IPv6 425 prefix. 427 9.2. Traffic Treatment Scenarios 429 The below table outlines how different permutations of connectivity 430 are treated in the 464XLAT architecture. 432 NOTE: 464XLAT double translation treatment will be stateless when a 433 dedicated /64 is available for translation on the CLAT. Otherwise, 434 the CLAT will have both stateful and stateless since it requires 435 NAT44 from the LAN to a single IPv4 address and then stateless 436 translation to a single IPv6 address. 438 +--------+-------------+-----------------------+-------------+ 439 | Server | Application | Traffic Treatment | Location of | 440 | | and Host | | Translation | 441 +--------+-------------+-----------------------+-------------+ 442 | IPv6 | IPv6 | End-to-end IPv6 | None | 443 +--------+-------------+-----------------------+-------------+ 444 | IPv4 | IPv6 | Stateful Translation | PLAT | 445 +--------+-------------+-----------------------+-------------+ 446 | IPv4 | IPv4 | 464XLAT | PLAT/CLAT | 447 +--------+-------------+-----------------------+-------------+ 449 Traffic Treatment Scenarios 451 10. Security Considerations 453 To implement a PLAT, see security considerations presented in Section 454 5 of [RFC6146]. 456 To implement a CLAT, see security considerations presented in Section 457 7 of [RFC6145]. The CLAT MAY comply with [RFC6092]. 459 11. IANA Considerations 461 This document has no actions for IANA. 463 12. Acknowledgements 465 The authors would like to thank JPIX NOC members, JPIX 464XLAT trial 466 service members, Seiichi Kawamura, Dan Drown, Brian Carpenter, Rajiv 467 Asati, Washam Fan, Behcet Sarikaya, Jan Zorz, Tatsuya Oishi, Lorenzo 468 Colitti, Erik Kline, Ole Troan, Maoke Chen, Gang Chen, Tom Petch, 469 Jouni Korhonen, Bjoern A. Zeeb, Hemant Singh, Vizdal Ales, Mark ZZZ 470 Smith, Mikael Abrahamsson, Tore Anderson, Teemu Savolainen, Alexandru 471 Petrescu, Gert Doering, Victor Kuarsingh, Ray Hunter, James Woodyatt, 472 and Tom Taylor for their helpful comments. Special acknowledgments 473 go to Remi Despres for his plentiful supports and suggestions, 474 especially about using NAT44 with IANA's EUI-64 ID. We also would 475 like to thank Fred Baker and Joel Jaeggli for their support. 477 13. References 479 13.1. Normative References 481 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 482 Requirement Levels", BCP 14, RFC 2119, March 1997. 484 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 485 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 486 October 2010. 488 [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation 489 Algorithm", RFC 6145, April 2011. 491 [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful 492 NAT64: Network Address and Protocol Translation from IPv6 493 Clients to IPv4 Servers", RFC 6146, April 2011. 495 13.2. Informative References 497 [I-D.ietf-behave-nat64-discovery-heuristic] 498 Savolainen, T., Korhonen, J., and D. Wing, "Discovery of 499 IPv6 Prefix Used for IPv6 Address Synthesis", 500 draft-ietf-behave-nat64-discovery-heuristic-11 (work in 501 progress), July 2012. 503 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 504 E. Lear, "Address Allocation for Private Internets", 505 BCP 5, RFC 1918, February 1996. 507 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 508 Host Configuration Protocol (DHCP) version 6", RFC 3633, 509 December 2003. 511 [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", 512 BCP 152, RFC 5625, August 2009. 514 [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in 515 Customer Premises Equipment (CPE) for Providing 516 Residential IPv6 Internet Service", RFC 6092, 517 January 2011. 519 [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van 520 Beijnum, "DNS64: DNS Extensions for Network Address 521 Translation from IPv6 Clients to IPv4 Servers", RFC 6147, 522 April 2011. 524 [RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T., 525 Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 526 Partnership Project (3GPP) Evolved Packet System (EPS)", 527 RFC 6459, January 2012. 529 [TS.23203] 3GPP, "Policy and charging control architecture", 3GPP 530 TS 23.203 10.7.0, June 2012. 532 Appendix A. Examples of IPv4/IPv6 Address Translation 534 The following is a example of IPv4/IPv6 Address Translation on the 535 464XLAT architecture. 537 In the case that an IPv6 prefix greater than /64 is assigned to an 538 end user by such as DHCPv6-PD [RFC3633], the CLAT can use a dedicated 539 /64 from the assigned IPv6 prefix. 541 Host & configuration value 542 +------------------------------+ 543 | IPv4 server | 544 | [198.51.100.1] | IP packet header 545 +------------------------------+ +--------------------------------+ 546 ^ | Destination IP address | 547 | | [198.51.100.1] | 548 | | Source IP address | 549 | | [192.0.2.1] | 550 +------------------------------+ +--------------------------------+ 551 | PLAT | ^ 552 | IPv4 pool address | | 553 | [192.0.2.1 - 192.0.2.100] | | 554 | PLAT-side XLATE IPv6 prefix | | 555 | [2001:db8:1234::/96] | | 556 +------------------------------+ +--------------------------------+ 557 ^ | Destination IP address | 558 | | [2001:db8:1234::198.51.100.1] | 559 | | Source IP address | 560 | | [2001:db8:aaaa::192.168.1.2] | 561 +------------------------------+ +--------------------------------+ 562 | CLAT | ^ 563 | PLAT-side XLATE IPv6 prefix | | 564 | [2001:db8:1234::/96] | | 565 | CLAT-side XLATE IPv6 prefix | | 566 | [2001:db8:aaaa::/96] | | 567 +------------------------------+ +--------------------------------+ 568 ^ | Destination IP address | 569 | | [198.51.100.1] | 570 | | Source IP address | 571 | | [192.168.1.2] | 572 +------------------------------+ +--------------------------------+ 573 | IPv4 client | 574 | [192.168.1.2/24] | 575 +------------------------------+ 576 Delegated IPv6 prefix for client: 2001:db8:aaaa::/56 578 Authors' Addresses 580 Masataka Mawatari 581 Japan Internet Exchange Co.,Ltd. 582 KDDI Otemachi Building 19F, 1-8-1 Otemachi, 583 Chiyoda-ku, Tokyo 100-0004 584 JAPAN 586 Phone: +81 3 3243 9579 587 Email: mawatari@jpix.ad.jp 589 Masanobu Kawashima 590 NEC AccessTechnica, Ltd. 591 800, Shimomata 592 Kakegawa-shi, Shizuoka 436-8501 593 JAPAN 595 Phone: +81 537 23 9655 596 Email: kawashimam@vx.jp.nec.com 598 Cameron Byrne 599 T-Mobile USA 600 Bellevue, Washington 98006 601 USA 603 Email: cameron.byrne@t-mobile.com