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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group H. Singh 3 Internet-Draft W. Beebee 4 Obsoletes: 6204 (if approved) Cisco Systems, Inc. 5 Intended status: Informational C. Donley 6 Expires: June 24, 2012 CableLabs 7 B. Stark 8 AT&T 9 O. Troan, Ed. 10 Cisco Systems, Inc. 11 December 22, 2011 13 Basic Requirements for IPv6 Customer Edge Routers 14 draft-ietf-v6ops-6204bis-05 16 Abstract 18 This document specifies requirements for an IPv6 Customer Edge (CE) 19 router. Specifically, the current version of this document focuses 20 on the basic provisioning of an IPv6 CE router and the provisioning 21 of IPv6 hosts attached to it. The document also covers IP transition 22 technologies. Two transition technologies in RFC 5969's 6rd and RFC 23 6333's DS-Lite. are covered in the document. The document obsoletes 24 RFC 6204, if approved. 26 Status of this Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on June 24, 2012. 43 Copyright Notice 45 Copyright (c) 2011 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 3.1. Current IPv4 End-User Network Architecture . . . . . . . . 4 65 3.2. IPv6 End-User Network Architecture . . . . . . . . . . . . 5 66 3.2.1. Local Communication . . . . . . . . . . . . . . . . . 6 67 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7 68 4.1. General Requirements . . . . . . . . . . . . . . . . . . . 7 69 4.2. WAN-Side Configuration . . . . . . . . . . . . . . . . . . 7 70 4.3. LAN-Side Configuration . . . . . . . . . . . . . . . . . . 11 71 4.4. Transition Technologies Support . . . . . . . . . . . . . 13 72 4.4.1. 6rd . . . . . . . . . . . . . . . . . . . . . . . . . 13 73 4.4.2. Dual-Stack Lite (DS-Lite) . . . . . . . . . . . . . . 14 74 4.5. Security Considerations . . . . . . . . . . . . . . . . . 14 75 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 76 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15 77 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 78 7.1. Normative References . . . . . . . . . . . . . . . . . . . 16 79 7.2. Informative References . . . . . . . . . . . . . . . . . . 18 80 Appendix A. Changes from RFC 6204 . . . . . . . . . . . . . . . . 19 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 83 1. Introduction 85 This document defines basic IPv6 features for a residential or small- 86 office router, referred to as an IPv6 CE router. Typically, these 87 routers also support IPv4. 89 Mixed environments of dual-stack hosts and IPv6-only hosts (behind 90 the CE router) can be more complex if the IPv6-only devices are using 91 a translator to access IPv4 servers [RFC6144]. Support for such 92 mixed environments is not in scope of this document. 94 This document specifies how an IPv6 CE router automatically 95 provisions its WAN interface, acquires address space for provisioning 96 of its LAN interfaces, and fetches other configuration information 97 from the service provider network. Automatic provisioning of more 98 complex topology than a single router with multiple LAN interfaces is 99 out of scope for this document. 101 See [RFC4779] for a discussion of options available for deploying 102 IPv6 in service provider access networks. 104 The document also covers IP transition technologies. Two transition 105 technologies in 6rd [RFC5969] and DS-Lite [RFC6333] are covered in 106 the document. At the time of writing this document these were the 107 only two transition technologies available in RFC form to be included 108 in this document. 110 1.1. Requirements Language 112 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 113 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 114 document are to be interpreted as described in RFC 2119 [RFC2119]. 116 2. Terminology 118 End-User Network one or more links attached to the IPv6 CE 119 router that connect IPv6 hosts. 121 IPv6 Customer Edge Router a node intended for home or small-office 122 use that forwards IPv6 packets not 123 explicitly addressed to itself. The IPv6 124 CE router connects the end-user network to 125 a service provider network. 127 IPv6 Host any device implementing an IPv6 stack 128 receiving IPv6 connectivity through the 129 IPv6 CE router. 131 LAN Interface an IPv6 CE router's attachment to a link in 132 the end-user network. Examples are 133 Ethernets (simple or bridged), 802.11 134 wireless, or other LAN technologies. An 135 IPv6 CE router may have one or more 136 network-layer LAN interfaces. 138 Service Provider an entity that provides access to the 139 Internet. In this document, a service 140 provider specifically offers Internet 141 access using IPv6, and may also offer IPv4 142 Internet access. The service provider can 143 provide such access over a variety of 144 different transport methods such as DSL, 145 cable, wireless, and others. 147 WAN Interface an IPv6 CE router's attachment to a link 148 used to provide connectivity to the service 149 provider network; example link technologies 150 include Ethernets (simple or bridged), PPP 151 links, Frame Relay, or ATM networks, as 152 well as Internet-layer (or higher-layer) 153 "tunnels", such as tunnels over IPv4 or 154 IPv6 itself. 156 3. Architecture 158 3.1. Current IPv4 End-User Network Architecture 160 An end-user network will likely support both IPv4 and IPv6. It is 161 not expected that an end-user will change their existing network 162 topology with the introduction of IPv6. There are some differences 163 in how IPv6 works and is provisioned; these differences have 164 implications for the network architecture. A typical IPv4 end-user 165 network consists of a "plug and play" router with NAT functionality 166 and a single link behind it, connected to the service provider 167 network. 169 A typical IPv4 NAT deployment by default blocks all incoming 170 connections. Opening of ports is typically allowed using a Universal 171 Plug and Play Internet Gateway Device (UPnP IGD) [UPnP-IGD] or some 172 other firewall control protocol. 174 Another consequence of using private address space in the end-user 175 network is that it provides stable addressing; i.e., it never changes 176 even when you change service providers, and the addresses are always 177 there even when the WAN interface is down or the customer edge router 178 has not yet been provisioned. 180 Rewriting addresses on the edge of the network also allows for some 181 rudimentary multihoming, even though using NATs for multihoming does 182 not preserve connections during a fail-over event [RFC4864]. 184 Many existing routers support dynamic routing, and advanced end-users 185 can build arbitrary, complex networks using manual configuration of 186 address prefixes combined with a dynamic routing protocol. 188 3.2. IPv6 End-User Network Architecture 190 The end-user network architecture for IPv6 should provide equivalent 191 or better capabilities and functionality than the current IPv4 192 architecture. 194 The end-user network is a stub network. Figure 1 illustrates the 195 model topology for the end-user network. 197 +-------+-------+ \ 198 | Service | \ 199 | Provider | | Service 200 | Router | | Provider 201 +-------+-------+ | network 202 | / 203 | Customer / 204 | Internet connection / 205 | 206 +------+--------+ \ 207 | IPv6 | \ 208 | Customer Edge | \ 209 | Router | / 210 +---+-------+-+-+ / 211 Network A | | Network B | End-User 212 ---+-------------+----+- --+--+-------------+--- | network(s) 213 | | | | \ 214 +----+-----+ +-----+----+ +----+-----+ +-----+----+ \ 215 |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | / 216 | | | | | | | | / 217 +----------+ +-----+----+ +----------+ +----------+ / 219 Figure 1: An Example of a Typical End-User Network 221 This architecture describes the: 223 o Basic capabilities of an IPv6 CE router 225 o Provisioning of the WAN interface connecting to the service 226 provider 228 o Provisioning of the LAN interfaces 230 For IPv6 multicast traffic, the IPv6 CE router may act as a Multicast 231 Listener Discovery (MLD) proxy [RFC4605] and may support a dynamic 232 multicast routing protocol. 234 The IPv6 CE router may be manually configured in an arbitrary 235 topology with a dynamic routing protocol. Automatic provisioning and 236 configuration are described for a single IPv6 CE router only. 238 3.2.1. Local Communication 240 Link-local IPv6 addresses are used by hosts communicating on a single 241 link. Unique Local IPv6 Unicast Addresses (ULAs) [RFC4193] are used 242 by hosts communicating within the end-user network across multiple 243 links, but without requiring the application to use a globally 244 routable address. The IPv6 CE router defaults to acting as the 245 demarcation point between two networks by providing a ULA boundary, a 246 multicast zone boundary, and ingress and egress traffic filters. 248 At the time of this writing, several host implementations do not 249 handle the case where they have an IPv6 address configured and no 250 IPv6 connectivity, either because the address itself has a limited 251 topological reachability (e.g., ULA) or because the IPv6 CE router is 252 not connected to the IPv6 network on its WAN interface. To support 253 host implementations that do not handle multihoming in a multi-prefix 254 environment [MULTIHOMING-WITHOUT-NAT], the IPv6 CE router should not, 255 as detailed in the requirements below, advertise itself as a default 256 router on the LAN interface(s) when it does not have IPv6 257 connectivity on the WAN interface or when it is not provisioned with 258 IPv6 addresses. For local IPv6 communication, the mechanisms 259 specified in [RFC4191] are used. 261 ULA addressing is useful where the IPv6 CE router has multiple LAN 262 interfaces with hosts that need to communicate with each other. If 263 the IPv6 CE router has only a single LAN interface (IPv6 link), then 264 link-local addressing can be used instead. 266 Coexistence with IPv4 requires any IPv6 CE router(s) on the LAN to 267 conform to these recommendations, especially requirements ULA-5 and 268 L-4 below. 270 4. Requirements 272 4.1. General Requirements 274 The IPv6 CE router is responsible for implementing IPv6 routing; that 275 is, the IPv6 CE router must look up the IPv6 destination address in 276 its routing table to decide to which interface it should send the 277 packet. 279 In this role, the IPv6 CE router is responsible for ensuring that 280 traffic using its ULA addressing does not go out the WAN interface, 281 and does not originate from the WAN interface. 283 G-1: An IPv6 CE router is an IPv6 node according to the IPv6 Node 284 Requirements [RFC4294] specification. 286 G-2: The IPv6 CE router MUST implement ICMPv6 according to 287 [RFC4443]. In particular, point-to-point links MUST be handled 288 as described in Section 3.1 of [RFC4443]. 290 G-3: The IPv6 CE router MUST NOT forward any IPv6 traffic between 291 its LAN interface(s) and its WAN interface until the router has 292 successfully completed the IPv6 address acquisition process. 294 G-4: By default, an IPv6 CE router that has no default router(s) on 295 its WAN interface MUST NOT advertise itself as an IPv6 default 296 router on its LAN interfaces. That is, the "Router Lifetime" 297 field is set to zero in all Router Advertisement messages it 298 originates [RFC4861]. 300 G-5: By default, if the IPv6 CE router is an advertising router and 301 loses its IPv6 default router(s) and/or detects loss of 302 connectivity on the WAN interface, it MUST explicitly 303 invalidate itself as an IPv6 default router on each of its 304 advertising interfaces by immediately transmitting one or more 305 Router Advertisement messages with the "Router Lifetime" field 306 set to zero [RFC4861]. 308 4.2. WAN-Side Configuration 310 The IPv6 CE router will need to support connectivity to one or more 311 access network architectures. This document describes an IPv6 CE 312 router that is not specific to any particular architecture or service 313 provider and that supports all commonly used architectures. 315 IPv6 Neighbor Discovery and DHCPv6 protocols operate over any type of 316 IPv6-supported link layer, and there is no need for a link-layer- 317 specific configuration protocol for IPv6 network-layer configuration 318 options as in, e.g., PPP IP Control Protocol (IPCP) for IPv4. This 319 section makes the assumption that the same mechanism will work for 320 any link layer, be it Ethernet, the Data Over Cable Service Interface 321 Specification (DOCSIS), PPP, or others. 323 WAN-side requirements: 325 W-1: When the router is attached to the WAN interface link, it MUST 326 act as an IPv6 host for the purposes of stateless [RFC4862] or 327 stateful [RFC3315] interface address assignment. 329 W-2: The IPv6 CE router MUST generate a link-local address and 330 finish Duplicate Address Detection according to [RFC4862] prior 331 to sending any Router Solicitations on the interface. The 332 source address used in the subsequent Router Solicitation MUST 333 be the link-local address on the WAN interface. 335 W-3: Absent other routing information, the IPv6 CE router MUST use 336 Router Discovery as specified in [RFC4861] to discover a 337 default router(s) and install default route(s) in its routing 338 table with the discovered router's address as the next hop. 340 W-4: The router MUST act as a requesting router for the purposes of 341 DHCPv6 prefix delegation ([RFC3633]). 343 W-5: DHCPv6 address assignment (IA_NA) and DHCPv6 prefix delegation 344 (IA_PD) SHOULD be done as a single DHCPv6 session. 346 W-6: The IPv6 CE router MUST use a persistent DHCP Unique Identifier 347 (DUID) for DHCPv6 messages. The DUID MUST NOT change between 348 network interface resets or IPv6 CE router reboots. 350 Link-layer requirements: 352 WLL-1: If the WAN interface supports Ethernet encapsulation, then 353 the IPv6 CE router MUST support IPv6 over Ethernet [RFC2464]. 355 WLL-2: If the WAN interface supports PPP encapsulation, the IPv6 CE 356 router MUST support IPv6 over PPP [RFC5072]. 358 WLL-3: If the WAN interface supports PPP encapsulation, in a dual- 359 stack environment with IPCP and IPV6CP running over one PPP 360 logical channel, the Network Control Protocols (NCPs) MUST be 361 treated as independent of each other and start and terminate 362 independently. 364 Address assignment requirements: 366 WAA-1: The IPv6 CE router MUST support Stateless Address 367 Autoconfiguration (SLAAC) [RFC4862]. 369 WAA-2: The IPv6 CE router MUST follow the recommendations in Section 370 4 of [RFC5942], and in particular the handling of the L flag 371 in the Router Advertisement Prefix Information option. 373 WAA-3: The IPv6 CE router MUST support DHCPv6 [RFC3315] client 374 behavior. 376 WAA-4: The IPv6 CE router MUST be able to support the following 377 DHCPv6 options: IA_NA, Reconfigure Accept [RFC3315], and 378 DNS_SERVERS [RFC3646]. The IPv6 CE router SHOULD be able to 379 support the DNS Search List DNSSL option as specified in 380 [RFC3646]. 382 WAA-5: The IPv6 CE router SHOULD support the DHCPv6 Simple Network 383 Time Protocol (SNTP) option [RFC4075] and the Information 384 Refresh Time option [RFC4242]. 386 WAA-6: If the IPv6 CE router receives a Router Advertisement message 387 (described in [RFC4861]) with the M flag set to 1, the IPv6 388 CE router MUST do DHCPv6 address assignment (request an IA_NA 389 option). 391 WAA-7: If the IPv6 CE router does not acquire global IPv6 392 address(es) from either SLAAC or DHCPv6, then it MUST create 393 global IPv6 address(es) from its delegated prefix(es) and 394 configure those on one of its internal virtual network 395 interfaces, unless configured to require a global IPv6 396 address on the WAN interface. 398 WAA-8: The CE Router MUST support the DHCPv6 SOL_MAX_RT option 399 [I-D.droms-dhc-dhcpv6-maxsolrt-update] in a received DHCPv6 400 Advertise or Reply message and set its internal SOL_MAX_RT 401 parameter to the value contained in the SOL_MAX_RT option. 403 WAA-9: As a router, the IPv6 CE router MUST follow the weak host 404 (Weak ES) model [RFC1122]. When originating packets from an 405 interface, it will use a source address from another one of 406 its interfaces if the outgoing interface does not have an 407 address of suitable scope. 409 Prefix delegation requirements: 411 WPD-1: The IPv6 CE router MUST support DHCPv6 prefix delegation 412 requesting router behavior as specified in [RFC3633] (IA_PD 413 option). 415 WPD-2: The IPv6 CE router MAY indicate as a hint to the delegating 416 router the size of the prefix it requires. If so, it MUST 417 ask for a prefix large enough to assign one /64 for each of 418 its interfaces, rounded up to the nearest nibble, and SHOULD 419 be configurable to ask for more. 421 WPD-3: The IPv6 CE router MUST be prepared to accept a delegated 422 prefix size different from what is given in the hint. If the 423 delegated prefix is too small to address all of its 424 interfaces, the IPv6 CE router SHOULD log a system management 425 error. 427 WPD-4: By default, the IPv6 CE router MUST initiate DHCPv6 prefix 428 delegation when either the M or O flags are set to 1 in a 429 received Router Advertisement message. 431 WPD-5: If the IPv6 CE router is configured to initiate DHCPv6 before 432 receiving a Router Advertisement, it MUST also request an 433 IA_NA option in DHCPv6. 435 WPD-6: If the delegated prefix(es) are aggregate route(s) of 436 multiple, more-specific routes, the IPv6 CE router MUST 437 discard packets that match the aggregate route(s), but not 438 any of the more-specific routes. In other words, the next 439 hop for the aggregate route(s) should be the null 440 destination. This is necessary to prevent forwarding loops 441 when some addresses covered by the aggregate are not 442 reachable [RFC4632]. 444 (a) The IPv6 CE router SHOULD send an ICMPv6 Destination 445 Unreachable message in accordance with Section 3.1 of 446 [RFC4443] back to the source of the packet, if the 447 packet is to be dropped due to this rule. 449 WPD-7: If the IPv6 CE router requests both an IA_NA and an IA_PD 450 option in DHCPv6, it MUST accept an IA_PD option in DHCPv6 451 Advertise/Reply messages, even if the message does not 452 contain any addresses, unless configured to only obtain its 453 WAN IPv6 address via DHCPv6. 455 WPD-8: By default, an IPv6 CE router MUST NOT initiate any dynamic 456 routing protocol on its WAN interface. 458 4.3. LAN-Side Configuration 460 The IPv6 CE router distributes configuration information obtained 461 during WAN interface provisioning to IPv6 hosts and assists IPv6 462 hosts in obtaining IPv6 addresses. It also supports connectivity of 463 these devices in the absence of any working WAN interface. 465 An IPv6 CE router is expected to support an IPv6 end-user network and 466 IPv6 hosts that exhibit the following characteristics: 468 1. Link-local addresses may be insufficient for allowing IPv6 469 applications to communicate with each other in the end-user 470 network. The IPv6 CE router will need to enable this 471 communication by providing globally scoped unicast addresses or 472 ULAs [RFC4193], whether or not WAN connectivity exists. 474 2. IPv6 hosts should be capable of using SLAAC and may be capable of 475 using DHCPv6 for acquiring their addresses. 477 3. IPv6 hosts may use DHCPv6 for other configuration information, 478 such as the DNS_SERVERS option for acquiring DNS information. 480 Unless otherwise specified, the following requirements apply to the 481 IPv6 CE router's LAN interfaces only. 483 ULA requirements: 485 ULA-1: The IPv6 CE router SHOULD be capable of generating a ULA 486 prefix [RFC4193]. 488 ULA-2: An IPv6 CE router with a ULA prefix MUST maintain this prefix 489 consistently across reboots. 491 ULA-3: The value of the ULA prefix SHOULD be user-configurable. 493 ULA-4: By default, the IPv6 CE router MUST act as a site border 494 router according to Section 4.3 of [RFC4193] and filter 495 packets with local IPv6 source or destination addresses 496 accordingly. 498 ULA-5: An IPv6 CE router MUST NOT advertise itself as a default 499 router with a Router Lifetime greater than zero whenever all 500 of its configured and delegated prefixes are ULA prefixes. 502 LAN requirements: 504 L-1: The IPv6 CE router MUST support router behavior according to 505 Neighbor Discovery for IPv6 [RFC4861]. 507 L-2: The IPv6 CE router MUST assign a separate /64 from its 508 delegated prefix(es) (and ULA prefix if configured to provide 509 ULA addressing) for each of its LAN interfaces. 511 L-3: An IPv6 CE router MUST advertise itself as a router for the 512 delegated prefix(es) (and ULA prefix if configured to provide 513 ULA addressing) using the "Route Information Option" specified 514 in Section 2.3 of [RFC4191]. This advertisement is 515 independent of having or not having IPv6 connectivity on the 516 WAN interface. 518 L-4: An IPv6 CE router MUST NOT advertise itself as a default 519 router with a Router Lifetime [RFC4861] greater than zero if 520 it has no prefixes configured or delegated to it. 522 L-5: The IPv6 CE router MUST make each LAN interface an advertising 523 interface according to [RFC4861]. 525 L-6: In Router Advertisement messages, the Prefix Information 526 option's A and L flags MUST be set to 1 by default. 528 L-7: The A and L flags' settings SHOULD be user-configurable. 530 L-8: The IPv6 CE router MUST support a DHCPv6 server capable of 531 IPv6 address assignment according to [RFC3315] OR a stateless 532 DHCPv6 server according to [RFC3736] on its LAN interfaces. 534 L-9: Unless the IPv6 CE router is configured to support the DHCPv6 535 IA_NA option, it SHOULD set the M flag to 0 and the O flag to 536 1 in its Router Advertisement messages [RFC4861]. 538 L-10: The IPv6 CE router MUST support providing DNS information in 539 the DHCPv6 DNS_SERVERS and DOMAIN_LIST options [RFC3646]. 541 L-11: The IPv6 CE router MUST support providing DNS information in 542 the Router Advertisement Recursive DNS Server (RDNSS) and 543 DNSSL options. 545 L-12: The IPv6 CE router SHOULD make available a subset of DHCPv6 546 options (as listed in Section 5.3 of [RFC3736]) received from 547 the DHCPv6 client on its WAN interface to its LAN-side DHCPv6 548 server. 550 L-13: If the delegated prefix changes, i.e., the current prefix is 551 replaced with a new prefix without any overlapping time 552 period, then the IPv6 CE router MUST immediately advertise the 553 old prefix with a Preferred Lifetime of zero and a Valid 554 Lifetime of either a) zero, or b) the lower of the current 555 Valid Lifetime and two hours (which must be decremented in 556 real time) in a Router Advertisement message as described in 557 Section 5.5.3, (e) of [RFC4862]. 559 L-14: The IPv6 CE router MUST send an ICMPv6 Destination Unreachable 560 message, code 5 (Source address failed ingress/egress policy) 561 for packets forwarded to it that use an address from a prefix 562 that has been deprecated. 564 4.4. Transition Technologies Support 566 4.4.1. 6rd 568 6rd [RFC5969] specifies an automatic tunneling mechanism tailored to 569 advance deployment of IPv6 to end users via a service provider's IPv4 570 network infrastructure. Key aspects include automatic IPv6 prefix 571 delegation to sites, stateless operation, simple provisioning, and 572 service that is equivalent to native IPv6 at the sites that are 573 served by the mechanism. It is expected that such traffic is 574 forwarded over the CE Router's native IPv4 WAN interface, and not 575 encapsulated in another tunnel. 577 The CE Router SHOULD support 6rd functionality. If 6rd is supported, 578 it MUST be implemented according to [RFC5969]. The following CE 579 Requirements also apply: 581 . 583 6rd requirements: 585 6RD-1: The IPv6 CE router MUST support 6rd configuration via the 6rd 586 DHCPv4 Option (212). If the CE router has obtained an IPv4 587 network address through some other means such PPP, it SHOULD 588 use the DHCPINFORM request message [RFC2131] to request the 589 6rd DHCPv4 Option. The IPv6 CE router MAY use other 590 mechanisms to configure 6rd parameters. Such mechanisms are 591 outside the scope of this document. 593 6RD-2: If the IPv6 CE router is capable of automated configuration 594 of IPv4 through IPCP (i.e., over a PPP connection), it MUST 595 support user-entered configuration of 6rd. 597 6RD-3: If the CE router supports configuration mechanisms other than 598 the 6rd DHCPv4 Option 212 (user-entered, TR-69, etc.), the CE 599 router MUST support 6rd in "hub and spoke" mode. 6rd in "hub 600 and spoke" requires all IPv6 traffic to go to the 6rd Border 601 Relay. In effect, this requirement removes the "direct 602 connect to 6rd" route defined in Section 7.1.1 of [RFC5969]. 604 4.4.2. Dual-Stack Lite (DS-Lite) 606 Dual-Stack Lite [RFC6333] enables both continued support for IPv4 607 services and incentives for the deployment of IPv6. It also de- 608 couples IPv6 deployment in the Service Provider network from the rest 609 of the Internet, making incremental deployment easier. Dual-Stack 610 Lite enables a broadband service provider to share IPv4 addresses 611 among customers by combining two well-known technologies: IP in IP 612 (IPv4-in-IPv6) and Network Address Translation (NAT). It is expected 613 that DS-Lite traffic is forwarded over the CE Router's native IPv6 614 WAN interface, and not encapsulated in another tunnel. 616 The IPv6 CE Router SHOULD implement DS-Lite functionality. If DS- 617 Lite is supported, it MUST be implemented according to [RFC6333]. 618 The following CE Router requirements also apply: 620 WAN requirements: 622 DLW-1: The CE Router MUST support DS-Lite via the DS-Lite DHCPv6 623 option [RFC6334]. The IPv6 CE Router MAY use other 624 mechanisms to configure DS-Lite parameters. Such mechanisms 625 are outside the scope of this document. 627 DLW-2: IPv6 CE Router MUST NOT perform IPv4 Network Address 628 Translation (NAT) on IPv4 traffic encapsulated using DS-Lite. 630 DLW-3: If the IPv6 CE Router is configured with an IPv4 address on 631 its WAN interface then the IPv6 CE Router SHOULD disable the 632 DS-Lite B4 element. 634 4.5. Security Considerations 636 It is considered a best practice to filter obviously malicious 637 traffic (e.g., spoofed packets, "Martian" addresses, etc.). Thus, 638 the IPv6 CE router ought to support basic stateless egress and 639 ingress filters. The CE router is also expected to offer mechanisms 640 to filter traffic entering the customer network; however, the method 641 by which vendors implement configurable packet filtering is beyond 642 the scope of this document. 644 Security requirements: 646 S-1: The IPv6 CE router SHOULD support [RFC6092]. In particular, 647 the IPv6 CE router SHOULD support functionality sufficient for 648 implementing the set of recommendations in [RFC6092], 649 Section 4. This document takes no position on whether such 650 functionality is enabled by default or mechanisms by which 651 users would configure it. 653 S-2: The IPv6 CE router MUST support ingress filtering in accordance 654 with BCP 38 [RFC2827]. 656 S-3: If the IPv6 CE router firewall is configured to filter incoming 657 tunneled data, the firewall SHOULD provide the capability to 658 filter decapsulated packets from a tunnel. 660 5. Acknowledgements 662 Thanks to the following people (in alphabetical order) for their 663 guidance and feedback: 665 Mikael Abrahamsson, Tore Anderson, Merete Asak, Scott Beuker, Mohamed 666 Boucadair, Rex Bullinger, Brian Carpenter, Tassos Chatzithomaoglou, 667 Lorenzo Colitti, Remi Denis-Courmont, Gert Doering, Alain Durand, 668 Katsunori Fukuoka, Tony Hain, Thomas Herbst, Kevin Johns, Erik Kline, 669 Stephen Kramer, Victor Kuarsingh, Francois-Xavier Le Bail, Arifumi 670 Matsumoto, David Miles, Shin Miyakawa, Jean-Francois Mule, Michael 671 Newbery, Carlos Pignataro, John Pomeroy, Antonio Querubin, Hiroki 672 Sato, Teemu Savolainen, Matt Schmitt, David Thaler, Mark Townsley, 673 Bernie Volz, Dan Wing, James Woodyatt, Carl Wuyts, and Cor Zwart. 675 This document is based in part on CableLabs' eRouter specification. 676 The authors wish to acknowledge the additional contributors from the 677 eRouter team: 679 Ben Bekele, Amol Bhagwat, Ralph Brown, Eduardo Cardona, Margo Dolas, 680 Toerless Eckert, Doc Evans, Roger Fish, Michelle Kuska, Diego 681 Mazzola, John McQueen, Harsh Parandekar, Michael Patrick, Saifur 682 Rahman, Lakshmi Raman, Ryan Ross, Ron da Silva, Madhu Sudan, Dan 683 Torbet, and Greg White. 685 6. Contributors 687 The following people have participated as co-authors or provided 688 substantial contributions to this document: Ralph Droms, Kirk 689 Erichsen, Fred Baker, Jason Weil, Lee Howard, Jean-Francois Tremblay, 690 Yiu Lee, John Jason Brzozowski, and Heather Kirksey. 692 7. References 694 7.1. Normative References 696 [I-D.droms-dhc-dhcpv6-maxsolrt-update] 697 Droms, R., "Modification to Default Value of MAX_SOL_RT", 698 draft-droms-dhc-dhcpv6-maxsolrt-update-00 (work in 699 progress), November 2011. 701 [RFC1102] Clark, D., "Policy routing in Internet protocols", 702 RFC 1102, May 1989. 704 [RFC1104] Braun, H., "Models of policy based routing", RFC 1104, 705 June 1989. 707 [RFC1122] Braden, R., "Requirements for Internet Hosts - 708 Communication Layers", STD 3, RFC 1122, October 1989. 710 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 711 E. Lear, "Address Allocation for Private Internets", 712 BCP 5, RFC 1918, February 1996. 714 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 715 Requirement Levels", BCP 14, RFC 2119, March 1997. 717 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 718 RFC 2131, March 1997. 720 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 721 Networks", RFC 2464, December 1998. 723 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 724 Defeating Denial of Service Attacks which employ IP Source 725 Address Spoofing", BCP 38, RFC 2827, May 2000. 727 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 728 and M. Carney, "Dynamic Host Configuration Protocol for 729 IPv6 (DHCPv6)", RFC 3315, July 2003. 731 [RFC3484] Draves, R., "Default Address Selection for Internet 732 Protocol version 6 (IPv6)", RFC 3484, February 2003. 734 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 735 Host Configuration Protocol (DHCP) version 6", RFC 3633, 736 December 2003. 738 [RFC3646] Droms, R., "DNS Configuration options for Dynamic Host 739 Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, 740 December 2003. 742 [RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol 743 (DHCP) Service for IPv6", RFC 3736, April 2004. 745 [RFC4075] Kalusivalingam, V., "Simple Network Time Protocol (SNTP) 746 Configuration Option for DHCPv6", RFC 4075, May 2005. 748 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 749 More-Specific Routes", RFC 4191, November 2005. 751 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 752 Addresses", RFC 4193, October 2005. 754 [RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh 755 Time Option for Dynamic Host Configuration Protocol for 756 IPv6 (DHCPv6)", RFC 4242, November 2005. 758 [RFC4294] Loughney, J., "IPv6 Node Requirements", RFC 4294, 759 April 2006. 761 [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control 762 Message Protocol (ICMPv6) for the Internet Protocol 763 Version 6 (IPv6) Specification", RFC 4443, March 2006. 765 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 766 "Internet Group Management Protocol (IGMP) / Multicast 767 Listener Discovery (MLD)-Based Multicast Forwarding 768 ("IGMP/MLD Proxying")", RFC 4605, August 2006. 770 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 771 (CIDR): The Internet Address Assignment and Aggregation 772 Plan", BCP 122, RFC 4632, August 2006. 774 [RFC4779] Asadullah, S., Ahmed, A., Popoviciu, C., Savola, P., and 775 J. Palet, "ISP IPv6 Deployment Scenarios in Broadband 776 Access Networks", RFC 4779, January 2007. 778 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 779 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 780 September 2007. 782 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 783 Address Autoconfiguration", RFC 4862, September 2007. 785 [RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and 786 E. Klein, "Local Network Protection for IPv6", RFC 4864, 787 May 2007. 789 [RFC5072] S.Varada, Haskins, D., and E. Allen, "IP Version 6 over 790 PPP", RFC 5072, September 2007. 792 [RFC5942] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet 793 Model: The Relationship between Links and Subnet 794 Prefixes", RFC 5942, July 2010. 796 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 797 Infrastructures (6rd) -- Protocol Specification", 798 RFC 5969, August 2010. 800 [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in 801 Customer Premises Equipment (CPE) for Providing 802 Residential IPv6 Internet Service", RFC 6092, 803 January 2011. 805 [RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 806 "IPv6 Router Advertisement Options for DNS Configuration", 807 RFC 6106, November 2010. 809 [RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O. 810 Troan, "Basic Requirements for IPv6 Customer Edge 811 Routers", RFC 6204, April 2011. 813 [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- 814 Stack Lite Broadband Deployments Following IPv4 815 Exhaustion", RFC 6333, August 2011. 817 [RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration 818 Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite", 819 RFC 6334, August 2011. 821 7.2. Informative References 823 [MULTIHOMING-WITHOUT-NAT] 824 Troan, O., Ed., Miles, D., Matsushima, S., Okimoto, T., 825 and D. Wing, "IPv6 Multihoming without Network Address 826 Translation", Work in Progress, December 2010. 828 [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for 829 IPv4/IPv6 Translation", RFC 6144, March 2011. 831 [UPnP-IGD] 832 UPnP Forum, "Universal Plug and Play (UPnP) Internet 833 Gateway Device (IGD)", November 2001, 834 . 836 Appendix A. Changes from RFC 6204 838 1. Added IP transition technologies available in RFC form. 840 2. Changed bullet G-5 to augment the condition of losing IPv6 841 default router(s) with loss of connectivity. 843 3. Removed bullet WAA-7 due to not reaching consensus by various 844 service provider standards bodies. The removal of text does not 845 remove any critical functionality from the CE specification. 847 4. Changed bullet WAA-8 to qualify WAN behavior only if not 848 configured to perform DHCPv6. This way a deployment specific 849 profile can mandate DHCPv6 numbered WAN wihout conflicting with 850 this document. 852 5. Changed the WPD-2 bullet from MUST be configurable to SHOULD be 853 configurable. 855 6. Changed bullet WPD-4 for a default behavior without compromising 856 any prior specification of the CE device. The change was needed 857 by a specific layer 1 deployment which wanted to specify a MUST 858 for DHCPv6 in their layer 1 profile and not conflict with this 859 document. 861 7. Changed bullet WPD-7 to qualify text for DHCPv6. 863 8. Added a new WAN DHCPv6 requirement for SOL_MAX_RT of DHCPv6 so 864 that if an service provider does not have DHCPv6 service enabled 865 CE routers do not send too frequent DHCPv6 requests to the 866 service provider DHCPv6 server. 868 9. Changed bullet L-11 from SHOULD provide DNS options in the RA to 869 MUST provide DNS option in the RA. 871 10. New bullet added to the Security Considerations section due to 872 addition of transition technology. The CE router filters 873 decapsulated 6rd data. 875 11. Minor change involved changing ICMP to ICMPv6. 877 Authors' Addresses 879 Hemant Singh 880 Cisco Systems, Inc. 881 1414 Massachusetts Ave. 882 Boxborough, MA 01719 883 USA 885 Phone: +1 978 936 1622 886 EMail: shemant@cisco.com 887 URI: http://www.cisco.com/ 889 Wes Beebee 890 Cisco Systems, Inc. 891 1414 Massachusetts Ave. 892 Boxborough, MA 01719 893 USA 895 Phone: +1 978 936 2030 896 EMail: wbeebee@cisco.com 897 URI: http://www.cisco.com/ 899 Chris Donley 900 CableLabs 901 858 Coal Creek Circle 902 Louisville, CO 80027 903 USA 905 EMail: c.donley@cablelabs.com 907 Barbara Stark 908 AT&T 909 725 W Peachtree St. 910 Atlanta, GA 30308 911 USA 913 EMail: barbara.stark@att.com 914 Ole Troan (editor) 915 Cisco Systems, Inc. 916 Telemarksvingen 20 917 N-0655 OSLO, 918 Norway 920 EMail: ot@cisco.com