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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force T. Chown 3 Internet-Draft Jisc 4 Obsoletes: 6434 (if approved) J. Loughney 5 Intended status: Best Current Practice Intel 6 Expires: September 4, 2018 T. Winters 7 UNH-IOL 8 March 3, 2018 10 IPv6 Node Requirements 11 draft-ietf-6man-rfc6434-bis-06 13 Abstract 15 This document defines requirements for IPv6 nodes. It is expected 16 that IPv6 will be deployed in a wide range of devices and situations. 17 Specifying the requirements for IPv6 nodes allows IPv6 to function 18 well and interoperate in a large number of situations and 19 deployments. 21 This document obsoletes RFC 6434, and in turn RFC 4294. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on September 4, 2018. 40 Copyright Notice 42 Copyright (c) 2018 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 58 1.1. Scope of This Document . . . . . . . . . . . . . . . . . 4 59 1.2. Description of IPv6 Nodes . . . . . . . . . . . . . . . . 5 60 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 61 3. Abbreviations Used in This Document . . . . . . . . . . . . . 5 62 4. Sub-IP Layer . . . . . . . . . . . . . . . . . . . . . . . . 5 63 5. IP Layer . . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 5.1. Internet Protocol Version 6 - RFC 8200 . . . . . . . . . 6 65 5.2. Support for IPv6 Extension Headers . . . . . . . . . . . 7 66 5.3. Protecting a node from excessive EH options . . . . . . . 8 67 5.4. Neighbor Discovery for IPv6 - RFC 4861 . . . . . . . . . 9 68 5.5. SEcure Neighbor Discovery (SEND) - RFC 3971 . . . . . . . 10 69 5.6. IPv6 Router Advertisement Flags Option - RFC 5175 . . . . 11 70 5.7. Path MTU Discovery and Packet Size . . . . . . . . . . . 11 71 5.7.1. Path MTU Discovery - RFC 8201 . . . . . . . . . . . . 11 72 5.7.2. Minimum MTU considerations . . . . . . . . . . . . . 12 73 5.8. ICMP for the Internet Protocol Version 6 (IPv6) - RFC 74 4443 . . . . . . . . . . . . . . . . . . . . . . . . . . 12 75 5.9. Default Router Preferences and More-Specific Routes - RFC 76 4191 . . . . . . . . . . . . . . . . . . . . . . . . . . 12 77 5.10. First-Hop Router Selection - RFC 8028 . . . . . . . . . . 12 78 5.11. Multicast Listener Discovery (MLD) for IPv6 - RFC 3810 . 12 79 5.12. Explicit Congestion Notification (ECN) - RFC 3168 . . . . 13 80 6. Addressing and Address Configuration . . . . . . . . . . . . 13 81 6.1. IP Version 6 Addressing Architecture - RFC 4291 . . . . . 13 82 6.2. Host Address Availability Recommendations . . . . . . . . 13 83 6.3. IPv6 Stateless Address Autoconfiguration - RFC 4862 . . . 14 84 6.4. Privacy Extensions for Address Configuration in IPv6 - 85 RFC 4941 . . . . . . . . . . . . . . . . . . . . . . . . 15 86 6.5. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 . 15 87 6.6. Default Address Selection for IPv6 - RFC 6724 . . . . . . 16 88 7. DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 89 8. Configuring Non-Address Information . . . . . . . . . . . . . 16 90 8.1. DHCP for Other Configuration Information . . . . . . . . 16 91 8.2. Router Advertisements and Default Gateway . . . . . . . . 17 92 8.3. IPv6 Router Advertisement Options for DNS 93 Configuration - RFC 8106 . . . . . . . . . . . . . . . . 17 94 8.4. DHCP Options versus Router Advertisement Options for Host 95 Configuration . . . . . . . . . . . . . . . . . . . . . . 17 96 9. Service Discovery Protocols . . . . . . . . . . . . . . . . . 18 97 10. IPv4 Support and Transition . . . . . . . . . . . . . . . . . 18 98 10.1. Transition Mechanisms . . . . . . . . . . . . . . . . . 18 99 10.1.1. Basic Transition Mechanisms for IPv6 Hosts and 100 Routers - RFC 4213 . . . . . . . . . . . . . . . . . 18 101 11. Application Support . . . . . . . . . . . . . . . . . . . . . 18 102 11.1. Textual Representation of IPv6 Addresses - RFC 5952 . . 18 103 11.2. Application Programming Interfaces (APIs) . . . . . . . 18 104 12. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . 19 105 13. Security . . . . . . . . . . . . . . . . . . . . . . . . . . 20 106 13.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 21 107 13.2. Transforms and Algorithms . . . . . . . . . . . . . . . 21 108 14. Router-Specific Functionality . . . . . . . . . . . . . . . . 22 109 14.1. IPv6 Router Alert Option - RFC 2711 . . . . . . . . . . 22 110 14.2. Neighbor Discovery for IPv6 - RFC 4861 . . . . . . . . . 22 111 14.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 . 22 112 14.4. IPv6 Prefix Length Recommendation for Forwarding - BCP 113 198 . . . . . . . . . . . . . . . . . . . . . . . . . . 23 114 15. Constrained Devices . . . . . . . . . . . . . . . . . . . . . 23 115 16. Network Management . . . . . . . . . . . . . . . . . . . . . 23 116 16.1. Management Information Base (MIB) Modules . . . . . . . 24 117 16.1.1. IP Forwarding Table MIB . . . . . . . . . . . . . . 24 118 16.1.2. Management Information Base for the Internet 119 Protocol (IP) . . . . . . . . . . . . . . . . . . . 24 120 16.1.3. Interface MIB . . . . . . . . . . . . . . . . . . . 24 121 16.2. YANG Data Models . . . . . . . . . . . . . . . . . . . . 24 122 16.2.1. IP Management YANG Model . . . . . . . . . . . . . . 24 123 16.2.2. Interface Management YANG Model . . . . . . . . . . 24 124 17. Security Considerations . . . . . . . . . . . . . . . . . . . 24 125 18. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 126 19. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 25 127 19.1. Authors and Acknowledgments (Current Document) . . . . . 25 128 19.2. Authors and Acknowledgments from RFC 6434 . . . . . . . 25 129 19.3. Authors and Acknowledgments from RFC 4294 . . . . . . . 25 130 20. Appendix: Changes from RFC 6434 . . . . . . . . . . . . . . . 25 131 21. Appendix: Changes from RFC 4294 . . . . . . . . . . . . . . . 27 132 22. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 133 22.1. Normative References . . . . . . . . . . . . . . . . . . 28 134 22.2. Informative References . . . . . . . . . . . . . . . . . 35 135 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 137 1. Introduction 139 This document defines common functionality required by both IPv6 140 hosts and routers. Many IPv6 nodes will implement optional or 141 additional features, but this document collects and summarizes 142 requirements from other published Standards Track documents in one 143 place. 145 This document tries to avoid discussion of protocol details and 146 references RFCs for this purpose. This document is intended to be an 147 applicability statement and to provide guidance as to which IPv6 148 specifications should be implemented in the general case and which 149 specifications may be of interest to specific deployment scenarios. 150 This document does not update any individual protocol document RFCs. 152 Although this document points to different specifications, it should 153 be noted that in many cases, the granularity of a particular 154 requirement will be smaller than a single specification, as many 155 specifications define multiple, independent pieces, some of which may 156 not be mandatory. In addition, most specifications define both 157 client and server behavior in the same specification, while many 158 implementations will be focused on only one of those roles. 160 This document defines a minimal level of requirement needed for a 161 device to provide useful internet service and considers a broad range 162 of device types and deployment scenarios. Because of the wide range 163 of deployment scenarios, the minimal requirements specified in this 164 document may not be sufficient for all deployment scenarios. It is 165 perfectly reasonable (and indeed expected) for other profiles to 166 define additional or stricter requirements appropriate for specific 167 usage and deployment environments. For example, this document does 168 not mandate that all clients support DHCP, but some deployment 169 scenarios may deem it appropriate to make such a requirement. For 170 example, government agencies in the USA have defined profiles for 171 specialized requirements for IPv6 in target environments (see 172 [USGv6]). 174 As it is not always possible for an implementer to know the exact 175 usage of IPv6 in a node, an overriding requirement for IPv6 nodes is 176 that they should adhere to Jon Postel's Robustness Principle: "Be 177 conservative in what you do, be liberal in what you accept from 178 others" [RFC0793]. 180 1.1. Scope of This Document 182 IPv6 covers many specifications. It is intended that IPv6 will be 183 deployed in many different situations and environments. Therefore, 184 it is important to develop requirements for IPv6 nodes to ensure 185 interoperability. 187 This document assumes that all IPv6 nodes meet the minimum 188 requirements specified here. 190 1.2. Description of IPv6 Nodes 192 From the Internet Protocol, Version 6 (IPv6) Specification [RFC8200], 193 we have the following definitions: 195 IPv6 node - a device that implements IPv6. 196 IPv6 router - a node that forwards IPv6 packets not explicitly 197 addressed to itself. 198 IPv6 host - any node that is not a router. 200 2. Requirements Language 202 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 203 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 204 document are to be interpreted as described in RFC 2119 [RFC2119]. 206 3. Abbreviations Used in This Document 208 AH Authentication Header 209 DAD Duplicate Address Detection 210 ESP Encapsulating Security Payload 211 ICMP Internet Control Message Protocol 212 IKE Internet Key Exchange 213 MIB Management Information Base 214 MLD Multicast Listener Discovery 215 MTU Maximum Transmission Unit 216 NA Neighbor Advertisement 217 NBMA Non-Broadcast Multiple Access 218 ND Neighbor Discovery 219 NS Neighbor Solicitation 220 NUD Neighbor Unreachability Detection 221 PPP Point-to-Point Protocol 223 4. Sub-IP Layer 225 An IPv6 node must include support for one or more IPv6 link-layer 226 specifications. Which link-layer specifications an implementation 227 should include will depend upon what link-layers are supported by the 228 hardware available on the system. It is possible for a conformant 229 IPv6 node to support IPv6 on some of its interfaces and not on 230 others. 232 As IPv6 is run over new layer 2 technologies, it is expected that new 233 specifications will be issued. In the following, we list some of the 234 layer 2 technologies for which an IPv6 specification has been 235 developed. It is provided for informational purposes only and may 236 not be complete. 238 - Transmission of IPv6 Packets over Ethernet Networks [RFC2464] 240 - Transmission of IPv6 Packets over Frame Relay Networks 241 Specification [RFC2590] 243 - Transmission of IPv6 Packets over IEEE 1394 Networks [RFC3146] 245 - Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) 246 Packets over Fibre Channel [RFC4338] 248 - Transmission of IPv6 Packets over IEEE 802.15.4 Networks [RFC4944] 250 - Transmission of IPv6 via the IPv6 Convergence Sublayer over IEEE 251 802.16 Networks [RFC5121] 253 - IP version 6 over PPP [RFC5072] 255 In addition to traditional physical link-layers, it is also possible 256 to tunnel IPv6 over other protocols. Examples include: 258 - Teredo: Tunneling IPv6 over UDP through Network Address 259 Translations (NATs) [RFC4380] 261 - Section 3 of "Basic Transition Mechanisms for IPv6 Hosts and 262 Routers" [RFC4213] 264 5. IP Layer 266 5.1. Internet Protocol Version 6 - RFC 8200 268 The Internet Protocol Version 6 is specified in [RFC8200]. This 269 specification MUST be supported. 271 The node MUST follow the packet transmission rules in RFC 8200. 273 All conformant IPv6 implementations MUST be capable of sending and 274 receiving IPv6 packets; forwarding functionality MAY be supported. 275 Nodes MUST always be able to send, receive, and process fragment 276 headers. 278 IPv6 nodes must not create overlapping fragments. Also, when 279 reassembling an IPv6 datagram, if one or more of its constituent 280 fragments is determined to be an overlapping fragment, the entire 281 datagram (and any constituent fragments) must be silently discarded. 282 See [RFC5722] for more information. 284 As recommended in [RFC8021], nodes MUST NOT generate atomic 285 fragments, i.e., where the fragment is a whole datagram. As per 287 [RFC6946], if a receiving node reassembling a datagram encounters an 288 atomic fragment, it should be processed as a fully reassembled 289 packet, and any other fragments that match this packet should be 290 processed independently. 292 [RFC6946] discusses IPv6 atomic fragments, and recommends that IPv6 293 atomic fragments are processed independently of any other fragments, 294 to protect against fragmentation-based attacks. 296 To mitigate a variety of potential attacks, nodes SHOULD avoid using 297 predictable fragment Identification values in Fragment Headers, as 298 discussed in [RFC7739]. 300 All nodes SHOULD support the setting and use of the IPv6 Flow Label 301 field as defined in the IPv6 Flow Label specification [RFC6437]. 302 Forwarding nodes such as routers and load distributors MUST NOT 303 depend only on Flow Label values being uniformly distributed. It is 304 RECOMMENDED that source hosts support the flow label by setting the 305 Flow Label field for all packets of a given flow to the same value 306 chosen from an approximation to a discrete uniform distribution. 308 5.2. Support for IPv6 Extension Headers 310 RFC 8200 specifies extension headers and the processing for these 311 headers. 313 Extension headers (except for the Hop-by-Hop Options header) are not 314 processed, inserted, or deleted by any node along a packet's delivery 315 path, until the packet reaches the node (or each of the set of nodes, 316 in the case of multicast) identified in the Destination Address field 317 of the IPv6 header. 319 Any unrecognized extension headers or options MUST be processed as 320 described in RFC 8200. Note that where Section 4 of RFC 8200 refers 321 to the action to be taken when a Next Header value in the current 322 header is not recognized by a node, that action applies whether the 323 value is an unrecognized Extension Header or an unrecognized upper 324 layer protocol (ULP). 326 An IPv6 node MUST be able to process these headers. An exception is 327 Routing Header type 0 (RH0), which was deprecated by [RFC5095] due to 328 security concerns and which MUST be treated as an unrecognized 329 routing type. 331 Further, [RFC7045] adds specific requirements for processing of 332 Extension Headers, in particular that any forwarding node along an 333 IPv6 packet's path, which forwards the packet for any reason, SHOULD 334 do so regardless of any extension headers that are present. 336 As per RFC 8200, when a node fragments an IPv6 datagram, it MUST 337 include the entire IPv6 Header Chain in the first fragment. The Per- 338 Fragment headers must consist of the IPv6 header plus any extension 339 headers that must be processed by nodes en route to the destination, 340 that is, all headers up to and including the Routing header if 341 present, else the Hop-by-Hop Options header if present, else no 342 extension headers. On reassembly, if the first fragment does not 343 include all headers through an Upper-Layer header, then that fragment 344 should be discarded and an ICMP Parameter Problem, Code 3, message 345 should be sent to the source of the fragment, with the Pointer field 346 set to zero. See [RFC7112] for a discussion of why oversized IPv6 347 Extension Header chains are avoided. 349 Defining new IPv6 extension headers is not recommended, unless there 350 are no existing IPv6 extension headers that can be used by specifying 351 a new option for that IPv6 extension header. A proposal to specify a 352 new IPv6 extension header must include a detailed technical 353 explanation of why an existing IPv6 extension header can not be used 354 for the desired new function, and in such cases need to follow the 355 format described in Section 8 of RFC 8200. For further background 356 reading on this topic, see [RFC6564]. 358 5.3. Protecting a node from excessive EH options 360 As per RFC 8200, end hosts are expected to process all extension 361 headers, destination options, and hop-by-hop options in a packet. 362 Given that the only limit on the number and size of extension headers 363 is the MTU, the processing of received packets could be considerable. 364 It is also conceivable that a long chain of extension headers might 365 be used as a form of denial-of-service attack. Accordingly, a host 366 may place limits on the number and sizes of extension headers and 367 options it is willing to process. 369 A host MAY limit the number of consecutive PAD1 options in 370 destination options or hop-by-hop options to seven. In this case, if 371 the more than seven consecutive PAD1 options are present the packet 372 should be silently discarded. The rationale is that if padding of 373 eight or more bytes is required than the PADN option should be used. 375 A host MAY limit number of bytes in a PADN option to be less than 376 eight. In such a case, if a PADN option is present that has a length 377 greater than seven then the packet should be silently discarded. The 378 rationale for this guideline is that the purpose of padding is for 379 alignment and eight bytes is the maximum alignment used in IPv6. 381 A host MAY disallow unknown options in destination options or hop-by- 382 hop options. This should be configurable where the default is to 383 accept unknown options and process them per [RFC8200]. If a packet 384 with unknown options is received and the host is configured to 385 disallow them, then the packet should be silently discarded. 387 A host MAY impose a limit on the maximum number of non-padding 388 options allowed in a destination options and hop-by-hop extension 389 headers. If this feature is supported the maximum number should be 390 configurable and the default value SHOULD be set to eight. The 391 limits for destination options and hop-by-hop options may be 392 separately configurable. If a packet is received and the number of 393 destination or hop-by-hop optines exceeds the limit, then the packet 394 should be silently discarded. 396 A host MAY impose a limit on the maximum length of destination 397 options or hop-by-hop options extension header. This value should be 398 configurable and the default is to accept options of any length. If 399 a packet is received and the length of destination or hop-by-hop 400 options extension header exceeds the length limit, then the packet 401 should be silently discarded. 403 5.4. Neighbor Discovery for IPv6 - RFC 4861 405 Neighbor Discovery is defined in [RFC4861]; the definition was 406 updated by [RFC5942]. Neighbor Discovery SHOULD be supported. RFC 407 4861 states: 409 Unless specified otherwise (in a document that covers operating IP 410 over a particular link type) this document applies to all link 411 types. However, because ND uses link-layer multicast for some of 412 its services, it is possible that on some link types (e.g., Non- 413 Broadcast Multi-Access (NBMA) links), alternative protocols or 414 mechanisms to implement those services will be specified (in the 415 appropriate document covering the operation of IP over a 416 particular link type). The services described in this document 417 that are not directly dependent on multicast, such as Redirects, 418 next-hop determination, Neighbor Unreachability Detection, etc., 419 are expected to be provided as specified in this document. The 420 details of how one uses ND on NBMA links are addressed in 421 [RFC2491]. 423 Some detailed analysis of Neighbor Discovery follows: 425 Router Discovery is how hosts locate routers that reside on an 426 attached link. Hosts MUST support Router Discovery functionality. 428 Prefix Discovery is how hosts discover the set of address prefixes 429 that define which destinations are on-link for an attached link. 430 Hosts MUST support Prefix Discovery. 432 Hosts MUST also implement Neighbor Unreachability Detection (NUD) for 433 all paths between hosts and neighboring nodes. NUD is not required 434 for paths between routers. However, all nodes MUST respond to 435 unicast Neighbor Solicitation (NS) messages. 437 [RFC7048] discusses NUD, in particular cases where it behaves too 438 impatiently. It states that if a node transmits more than a certain 439 number of packets, then it SHOULD use the exponential backoff of the 440 retransmit timer, up to a certain threshold point. 442 Hosts MUST support the sending of Router Solicitations and the 443 receiving of Router Advertisements. The ability to understand 444 individual Router Advertisement options is dependent on supporting 445 the functionality making use of the particular option. 447 [RFC7559] discusses packet loss resliency for Router Solicitations, 448 and requires that nodes MUST use a specific exponential backoff 449 algorithm for RS retransmissions. 451 All nodes MUST support the sending and receiving of Neighbor 452 Solicitation (NS) and Neighbor Advertisement (NA) messages. NS and 453 NA messages are required for Duplicate Address Detection (DAD). 455 Hosts SHOULD support the processing of Redirect functionality. 456 Routers MUST support the sending of Redirects, though not necessarily 457 for every individual packet (e.g., due to rate limiting). Redirects 458 are only useful on networks supporting hosts. In core networks 459 dominated by routers, Redirects are typically disabled. The sending 460 of Redirects SHOULD be disabled by default on backbone routers. They 461 MAY be enabled by default on routers intended to support hosts on 462 edge networks. 464 "IPv6 Host-to-Router Load Sharing" [RFC4311] includes additional 465 recommendations on how to select from a set of available routers. 466 [RFC4311] SHOULD be supported. 468 5.5. SEcure Neighbor Discovery (SEND) - RFC 3971 470 SEND [RFC3971] and Cryptographically Generated Addresses (CGAs) 471 [RFC3972] provide a way to secure the message exchanges of Neighbor 472 Discovery. SEND has the potential to address certain classes of 473 spoofing attacks, but it does not provide specific protection for 474 threats from off-link attackers. 476 There have been relatively few implementations of SEND in common 477 operating systems and platforms since its publication in 2005, and 478 thus deployment experience remains very limited to date. 480 At this time, support for SEND is considered optional. Due to the 481 complexity in deploying SEND, and its heavyweight provisioning, its 482 deployment is only likely to be considered where nodes are operating 483 in a particularly strict security environment. 485 5.6. IPv6 Router Advertisement Flags Option - RFC 5175 487 Router Advertisements include an 8-bit field of single-bit Router 488 Advertisement flags. The Router Advertisement Flags Option extends 489 the number of available flag bits by 48 bits. At the time of this 490 writing, 6 of the original 8 single-bit flags have been assigned, 491 while 2 remain available for future assignment. No flags have been 492 defined that make use of the new option, and thus, strictly speaking, 493 there is no requirement to implement the option today. However, 494 implementations that are able to pass unrecognized options to a 495 higher-level entity that may be able to understand them (e.g., a 496 user-level process using a "raw socket" facility) MAY take steps to 497 handle the option in anticipation of a future usage. 499 5.7. Path MTU Discovery and Packet Size 501 5.7.1. Path MTU Discovery - RFC 8201 503 "Path MTU Discovery for IP version 6" [RFC8201] SHOULD be supported. 504 From [RFC8200]: 506 It is strongly recommended that IPv6 nodes implement Path MTU 507 Discovery [RFC8201], in order to discover and take advantage of 508 path MTUs greater than 1280 octets. However, a minimal IPv6 509 implementation (e.g., in a boot ROM) may simply restrict itself to 510 sending packets no larger than 1280 octets, and omit 511 implementation of Path MTU Discovery. 513 The rules in [RFC8200] and [RFC5722] MUST be followed for packet 514 fragmentation and reassembly. 516 As described in RFC 8201, nodes implementing Path MTU Discovery and 517 sending packets larger than the IPv6 minimum link MTU are susceptible 518 to problematic connectivity if ICMPv6 messages are blocked or not 519 transmitted. For example, this will result in connections that 520 complete the TCP three- way handshake correctly but then hang when 521 data is transferred. This state is referred to as a black-hole 522 connection [RFC2923]. Path MTU Discovery relies on ICMPv6 Packet Too 523 Big (PTB) to determine the MTU of the path (and thus these should not 524 be filtered, as per the recommendation in [RFC4890]). 526 An extension to Path MTU Discovery defined in RFC 8201 can be found 527 in [RFC4821], which defines a method for Packetization Layer Path MTU 528 Discovery (PLPMTUD) designed for use over paths where delivery of 529 ICMPv6 messages to a host is not assured. 531 5.7.2. Minimum MTU considerations 533 While an IPv6 link MTU can be set to 1280 bytes, it is recommended 534 that for IPv6 UDP in particular, which includes DNS operation, the 535 sender use a large MTU if they can, in order to avoid gratuitous 536 fragmentation-caused packet drops. 538 5.8. ICMP for the Internet Protocol Version 6 (IPv6) - RFC 4443 540 ICMPv6 [RFC4443] MUST be supported. "Extended ICMP to Support Multi- 541 Part Messages" [RFC4884] MAY be supported. 543 5.9. Default Router Preferences and More-Specific Routes - RFC 4191 545 "Default Router Preferences and More-Specific Routes" [RFC4191] 546 provides support for nodes attached to multiple (different) networks, 547 each providing routers that advertise themselves as default routers 548 via Router Advertisements. In some scenarios, one router may provide 549 connectivity to destinations the other router does not, and choosing 550 the "wrong" default router can result in reachability failures. In 551 order to resolve this scenario IPv6 Nodes MUST implement [RFC4191] 552 and SHOULD implement the Type C host role defined in RFC4191. 554 5.10. First-Hop Router Selection - RFC 8028 556 In multihomed scenarios, where a host has more than one prefix, each 557 allocated by an upstream network that is assumed to implement BCP 38 558 ingress filtering, the host may have multiple routers to choose from. 560 Hosts that may be deployed in such multihomed environments SHOULD 561 follow the guidance given in [RFC8028]. 563 5.11. Multicast Listener Discovery (MLD) for IPv6 - RFC 3810 565 Nodes that need to join multicast groups MUST support MLDv2 566 [RFC3810]. MLD is needed by any node that is expected to receive and 567 process multicast traffic and in particular MLDv2 is required for 568 support for source-specific multicast (SSM) as per [RFC4607]. 570 Previous versions of this document only required MLDv1 ([RFC2710]) to 571 be implemented on all nodes. Since participation of any MLDv1-only 572 nodes on a link require that all other nodeas on the link then 573 operate in version 1 compatibility mode, the requirement to support 574 MLDv2 on all nodes was upgraded to a MUST. Further, SSM is now the 575 preferred multicast distribution method, rather than ASM. 577 Note that Neighbor Discovery (as used on most link types -- see 578 Section 5.4) depends on multicast and requires that nodes join 579 Solicited Node multicast addresses. 581 5.12. Explicit Congestion Notification (ECN) - RFC 3168 583 An ECN-aware router may set a mark in the IP header in order to 584 signal impending congestion, rather than dropping a packet. The 585 receiver of the packet echoes the congestion indication to the 586 sender, which can then reduce its transmission rate as if it detected 587 a dropped packet. 589 Nodes that may be deployed in environments where they would benefit 590 from such early congestion notification SHOULD implement [RFC3168]. 591 In such cases, the updates presented in [RFC8311] may also be 592 relevant. 594 6. Addressing and Address Configuration 596 6.1. IP Version 6 Addressing Architecture - RFC 4291 598 The IPv6 Addressing Architecture [RFC4291] MUST be supported. 600 The current IPv6 Address Architecture is based on a 64-bit boundary 601 for subnet prefixes. The reasoning behind this decision is 602 documented in [RFC7421]. 604 Implementations MUST also support the Multicast flag updates 605 documented in [RFC7371] 607 6.2. Host Address Availability Recommendations 609 Hosts may be configured with addresses through a variety of methods, 610 including SLAAC, DHCPv6, or manual configuration. 612 [RFC7934] recommends that networks provide general-purpose end hosts 613 with multiple global IPv6 addresses when they attach, and it 614 describes the benefits of and the options for doing so. Routers 615 SHOULD support [RFC7934] for assigning multiple address to a host. 616 Host SHOULD support assigning multiple addresses as described in 617 [RFC7934]. 619 Nodes SHOULD support the capability to be assigned a prefix per host 620 as documented in [RFC8273]. Such an approach can offer improved host 621 isolation and enhanced subscriber management on shared network 622 segments. 624 6.3. IPv6 Stateless Address Autoconfiguration - RFC 4862 626 Hosts MUST support IPv6 Stateless Address Autoconfiguration. It is 627 recommended, as described in [RFC8064], that unless there is a 628 specific requirement for MAC addresses to be embedded in an IID, 629 nodes follow the procedure in [RFC7217] to generate SLAAC-based 630 addresses, rather than using [RFC4862]. Addresses generated through 631 RFC7217 will be the same whenever a given device (re)appears on the 632 same subnet (with a specific IPv6 prefix), but the IID will vary on 633 each subnet visited. 635 Nodes that are routers MUST be able to generate link-local addresses 636 as described in [RFC4862]. 638 From RFC 4862: 640 The autoconfiguration process specified in this document applies 641 only to hosts and not routers. Since host autoconfiguration uses 642 information advertised by routers, routers will need to be 643 configured by some other means. However, it is expected that 644 routers will generate link-local addresses using the mechanism 645 described in this document. In addition, routers are expected to 646 successfully pass the Duplicate Address Detection procedure 647 described in this document on all addresses prior to assigning 648 them to an interface. 650 All nodes MUST implement Duplicate Address Detection. Quoting from 651 Section 5.4 of RFC 4862: 653 Duplicate Address Detection MUST be performed on all unicast 654 addresses prior to assigning them to an interface, regardless of 655 whether they are obtained through stateless autoconfiguration, 656 DHCPv6, or manual configuration, with the following [exceptions 657 noted therein]. 659 "Optimistic Duplicate Address Detection (DAD) for IPv6" [RFC4429] 660 specifies a mechanism to reduce delays associated with generating 661 addresses via Stateless Address Autoconfiguration [RFC4862]. RFC 662 4429 was developed in conjunction with Mobile IPv6 in order to reduce 663 the time needed to acquire and configure addresses as devices quickly 664 move from one network to another, and it is desirable to minimize 665 transition delays. For general purpose devices, RFC 4429 remains 666 optional at this time. 668 [RFC7527] discusses enhanced DAD, and describes an algorithm to 669 automate the detection of looped back IPv6 ND messages used by DAD. 670 Nodes SHOULD implement this behaviour where such detection is 671 beneficial. 673 6.4. Privacy Extensions for Address Configuration in IPv6 - RFC 4941 675 A node using Stateless Address Autoconfiguration [RFC4862] to form a 676 globally unique IPv6 address using its MAC address to generate the 677 IID will see that IID remain the same on any visited network, even 678 though the network prefix part changes. Thus it is possible for 3rd 679 party devices such nodes communicate with to track the activities of 680 the node as it moves around the network. Privacy Extensions for 681 Stateless Address Autoconfiguration [RFC4941] address this concern by 682 allowing nodes to configure an additional temporary address where the 683 IID is effectively randomly generated. Privacy addresses are then 684 used as source addresses for new communications initiated by the 685 node. 687 General issues regarding privacy issues for IPv6 addressing are 688 discussed in [RFC7721]. 690 RFC 4941 SHOULD be supported. In some scenarios, such as dedicated 691 servers in a data center, it provides limited or no benefit, or may 692 complicate network management. Thus devices implementing this 693 specification MUST provide a way for the end user to explicitly 694 enable or disable the use of such temporary addresses. 696 Note that RFC4941 can be used independently of traditional SLAAC, or 697 of RFC7217-based SLAAC. 699 Implementers of RFC 4941 should be aware that certain addresses are 700 reserved and should not be chosen for use as temporary addresses. 701 Consult "Reserved IPv6 Interface Identifiers" [RFC5453] for more 702 details. 704 6.5. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 706 DHCPv6 [RFC3315] can be used to obtain and configure addresses. In 707 general, a network may provide for the configuration of addresses 708 through SLAAC, DHCPv6, or both. There will be a wide range of IPv6 709 deployment models and differences in address assignment requirements, 710 some of which may require DHCPv6 for stateful address assignment. 711 Consequently, all hosts SHOULD implement address configuration via 712 DHCPv6. 714 In the absence of observed Router Advertisement messages, IPv6 nodes 715 MAY initiate DHCP to obtain IPv6 addresses and other configuration 716 information, as described in Section 5.5.2 of [RFC4862]. 718 Where devices are likely to be carried by users and attached to 719 multiple visisted networks, DHCPv6 client anonymity profiles SHOULD 720 be supported as described in [RFC7844] to minimise the disclosure of 721 identifying information. Section 5 of RFC7844 describes operational 722 considerations on the use of such anonymity profiles. 724 6.6. Default Address Selection for IPv6 - RFC 6724 726 IPv6 nodes will invariably have multiple addresses configured 727 simultaneously, and thus will need to choose which addresses to use 728 for which communications. The rules specified in the Default Address 729 Selection for IPv6 [RFC6724] document MUST be implemented. [RFC8028] 730 updates rule 5.5 from [RFC6724]; implementations SHOULD implement 731 this rule. 733 7. DNS 735 DNS is described in [RFC1034], [RFC1035], [RFC3363], and [RFC3596]. 736 Not all nodes will need to resolve names; those that will never need 737 to resolve DNS names do not need to implement resolver functionality. 738 However, the ability to resolve names is a basic infrastructure 739 capability on which applications rely, and most nodes will need to 740 provide support. All nodes SHOULD implement stub-resolver [RFC1034] 741 functionality, as in [RFC1034], Section 5.3.1, with support for: 743 - AAAA type Resource Records [RFC3596]; 745 - reverse addressing in ip6.arpa using PTR records [RFC3596]; 747 - Extension Mechanisms for DNS (EDNS0) [RFC6891] to allow for DNS 748 packet sizes larger than 512 octets. 750 Those nodes are RECOMMENDED to support DNS security extensions 751 [RFC4033] [RFC4034] [RFC4035]. 753 A6 Resource Records, which were only ever defined with Experimental 754 status in [RFC3363], are now classified as Historic, as per 755 [RFC6563]. 757 8. Configuring Non-Address Information 759 8.1. DHCP for Other Configuration Information 761 DHCP [RFC3315] Specifies a mechanism for IPv6 nodes to obtain address 762 configuration information (see Section 6.5) and to obtain additional 763 (non-address) configuration. If a host implementation supports 764 applications or other protocols that require configuration that is 765 only available via DHCP, hosts SHOULD implement DHCP. For 766 specialized devices on which no such configuration need is present, 767 DHCP may not be necessary. 769 An IPv6 node can use the subset of DHCP (described in [RFC3736]) to 770 obtain other configuration information. 772 If an IPv6 node implements DHCP it MUST implement the DNS options 773 [RFC3646] as most deployments will expect these options are 774 available. 776 8.2. Router Advertisements and Default Gateway 778 There is no defined DHCPv6 Gateway option. 780 Nodes using the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 781 are thus expected to determine their default router information and 782 on-link prefix information from received Router Advertisements. 784 8.3. IPv6 Router Advertisement Options for DNS Configuration - RFC 8106 786 Router Advertisement Options have historically been limited to those 787 that are critical to basic IPv6 functionality. Originally, DNS 788 configuration was not included as an RA option, and DHCP was the 789 recommended way to obtain DNS configuration information. Over time, 790 the thinking surrounding such an option has evolved. It is now 791 generally recognized that few nodes can function adequately without 792 having access to a working DNS resolver, and thus a Standards Track 793 document has been published to provide this capability [RFC8106]. 795 Implementations MUST include support for the DNS RA option [RFC8106]. 797 8.4. DHCP Options versus Router Advertisement Options for Host 798 Configuration 800 In IPv6, there are two main protocol mechanisms for propagating 801 configuration information to hosts: Router Advertisements (RAs) and 802 DHCP. RA options have been restricted to those deemed essential for 803 basic network functioning and for which all nodes are configured with 804 exactly the same information. Examples include the Prefix 805 Information Options, the MTU option, etc. On the other hand, DHCP 806 has generally been preferred for configuration of more general 807 parameters and for parameters that may be client-specific. Generally 808 speaking, however, there has been a desire to define only one 809 mechanism for configuring a given option, rather than defining 810 multiple (different) ways of configuring the same information. 812 One issue with having multiple ways of configuring the same 813 information is that interoperability suffers if a host chooses one 814 mechanism but the network operator chooses a different mechanism. 815 For "closed" environments, where the network operator has significant 816 influence over what devices connect to the network and thus what 817 configuration mechanisms they support, the operator may be able to 818 ensure that a particular mechanism is supported by all connected 819 hosts. In more open environments, however, where arbitrary devices 820 may connect (e.g., a WIFI hotspot), problems can arise. To maximize 821 interoperability in such environments, hosts would need to implement 822 multiple configuration mechanisms to ensure interoperability. 824 9. Service Discovery Protocols 826 [RFC6762] and [RFC6763] describe multicast DNS (mDNS) and DNS-Based 827 Service Discovery (DNS-SD) respectively. These protocols, 828 collectively commonly referred to as the 'Bonjour' protocols after 829 their naming by Apple, provide the means for devices to discover 830 services within a local link and, in the absence of a unicast DNS 831 service, to exchange naming information. 833 Where devices are to be deployed in networks where service dicovery 834 would be beneficial, e.g., for users seeking to discover printers or 835 display devices, mDNS and DNS-SD SHOULD be supported. 837 The IETF dnssd WG is defining solutions for DNS-based service 838 discovery in multi-link networks. 840 10. IPv4 Support and Transition 842 IPv6 nodes MAY support IPv4. 844 10.1. Transition Mechanisms 846 10.1.1. Basic Transition Mechanisms for IPv6 Hosts and Routers - RFC 847 4213 849 If an IPv6 node implements dual stack and tunneling, then [RFC4213] 850 MUST be supported. 852 11. Application Support 854 11.1. Textual Representation of IPv6 Addresses - RFC 5952 856 Software that allows users and operators to input IPv6 addresses in 857 text form SHOULD support "A Recommendation for IPv6 Address Text 858 Representation" [RFC5952]. 860 11.2. Application Programming Interfaces (APIs) 862 There are a number of IPv6-related APIs. This document does not 863 mandate the use of any, because the choice of API does not directly 864 relate to on-the-wire behavior of protocols. Implementers, however, 865 would be advised to consider providing a common API or reviewing 866 existing APIs for the type of functionality they provide to 867 applications. 869 "Basic Socket Interface Extensions for IPv6" [RFC3493] provides IPv6 870 functionality used by typical applications. Implementers should note 871 that RFC3493 has been picked up and further standardized by the 872 Portable Operating System Interface (POSIX) [POSIX]. 874 "Advanced Sockets Application Program Interface (API) for IPv6" 875 [RFC3542] provides access to advanced IPv6 features needed by 876 diagnostic and other more specialized applications. 878 "IPv6 Socket API for Source Address Selection" [RFC5014] provides 879 facilities that allow an application to override the default Source 880 Address Selection rules of [RFC6724]. 882 "Socket Interface Extensions for Multicast Source Filters" [RFC3678] 883 provides support for expressing source filters on multicast group 884 memberships. 886 "Extension to Sockets API for Mobile IPv6" [RFC4584] provides 887 application support for accessing and enabling Mobile IPv6 [RFC6275] 888 features. 890 12. Mobility 892 Mobile IPv6 [RFC6275] and associated specifications [RFC3776] 893 [RFC4877] allow a node to change its point of attachment within the 894 Internet, while maintaining (and using) a permanent address. All 895 communication using the permanent address continues to proceed as 896 expected even as the node moves around. The definition of Mobile IP 897 includes requirements for the following types of nodes: 899 - mobile nodes 901 - correspondent nodes with support for route optimization 903 - home agents 905 - all IPv6 routers 907 At the present time, Mobile IP has seen only limited implementation 908 and no significant deployment, partly because it originally assumed 909 an IPv6-only environment rather than a mixed IPv4/IPv6 Internet. 910 Recently, additional work has been done to support mobility in mixed- 911 mode IPv4 and IPv6 networks [RFC5555]. 913 More usage and deployment experience is needed with mobility before 914 any specific approach can be recommended for broad implementation in 915 all hosts and routers. Consequently, [RFC6275], [RFC5555], and 916 associated standards such as [RFC4877] are considered a MAY at this 917 time. 919 IPv6 for 3GPP [RFC7066] lists a snapshot of required IPv6 920 Functionalities at the time the document was published that would 921 need to be implemented, going above and beyond the recommendations in 922 this document. Additionally a 3GPP IPv6 Host MAY implement [RFC7278] 923 for delivering IPv6 prefixes on the LAN link. 925 13. Security 927 This section describes the specification for security for IPv6 nodes. 929 Achieving security in practice is a complex undertaking. Operational 930 procedures, protocols, key distribution mechanisms, certificate 931 management approaches, etc., are all components that impact the level 932 of security actually achieved in practice. More importantly, 933 deficiencies or a poor fit in any one individual component can 934 significantly reduce the overall effectiveness of a particular 935 security approach. 937 IPsec either can provide end-to-end security between nodes or or can 938 provide channel security (for example, via a site-to-site IPsec VPN), 939 making it possible to provide secure communication for all (or a 940 subset of) communication flows at the IP layer between pairs of 941 internet nodes. IPsec has two standard operating modes, Tunnel-mode 942 and Transport-mode. In Tunnel-mode, IPsec provides network-layer 943 security and protects an entire IP packet by encapsulating the 944 orginal IP packet and then pre-pending a new IP header. In 945 Transport-mode, IPsec provides security for the transport-layer (and 946 above) by encapsulating only the transport-layer (and above) portion 947 of the IP packet (i.e., without adding a 2nd IP header). 949 Although IPsec can be used with manual keying in some cases, such 950 usage has limited applicability and is not recommended. 952 A range of security technologies and approaches proliferate today 953 (e.g., IPsec, Transport Layer Security (TLS), Secure SHell (SSH), SSL 954 VPNS, etc.) No one approach has emerged as an ideal technology for 955 all needs and environments. Moreover, IPsec is not viewed as the 956 ideal security technology in all cases and is unlikely to displace 957 the others. 959 Previously, IPv6 mandated implementation of IPsec and recommended the 960 key management approach of IKE. This document updates that 961 recommendation by making support of the IPsec Architecture [RFC4301] 962 a SHOULD for all IPv6 nodes. Note that the IPsec Architecture 963 requires (e.g., Section 4.5 of RFC 4301) the implementation of both 964 manual and automatic key management. Currently, the default 965 automated key management protocol to implement is IKEv2 [RFC7296]. 967 This document recognizes that there exists a range of device types 968 and environments where approaches to security other than IPsec can be 969 justified. For example, special-purpose devices may support only a 970 very limited number or type of applications, and an application- 971 specific security approach may be sufficient for limited management 972 or configuration capabilities. Alternatively, some devices may run 973 on extremely constrained hardware (e.g., sensors) where the full 974 IPsec Architecture is not justified. 976 Because most common platforms now support IPv6 and have it enabled by 977 default, IPv6 security is an issue for networks that are ostensibly 978 IPv4-only; see [RFC7123] for guidance on this area. 980 13.1. Requirements 982 "Security Architecture for the Internet Protocol" [RFC4301] SHOULD be 983 supported by all IPv6 nodes. Note that the IPsec Architecture 984 requires (e.g., Section 4.5 of [RFC4301]) the implementation of both 985 manual and automatic key management. Currently, the default 986 automated key management protocol to implement is IKEv2. As required 987 in [RFC4301], IPv6 nodes implementing the IPsec Architecture MUST 988 implement ESP [RFC4303] and MAY implement AH [RFC4302]. 990 13.2. Transforms and Algorithms 992 The current set of mandatory-to-implement algorithms for the IPsec 993 Architecture are defined in "Cryptographic Algorithm Implementation 994 Requirements For ESP and AH" [RFC8221]. IPv6 nodes implementing the 995 IPsec Architecture MUST conform to the requirements in [RFC8221]. 996 Preferred cryptographic algorithms often change more frequently than 997 security protocols. Therefore, implementations MUST allow for 998 migration to new algorithms, as RFC 8221 is replaced or updated in 999 the future. 1001 The current set of mandatory-to-implement algorithms for IKEv2 are 1002 defined in "Cryptographic Algorithms for Use in the Internet Key 1003 Exchange Version 2 (IKEv2)" [RFC8247]. IPv6 nodes implementing IKEv2 1004 MUST conform to the requirements in [RFC8247] and/or any future 1005 updates or replacements to [RFC8247]. 1007 14. Router-Specific Functionality 1009 This section defines general host considerations for IPv6 nodes that 1010 act as routers. Currently, this section does not discuss detailed 1011 routing-specific requirements. For the case of typical home routers, 1012 [RFC7084] defines basic requirements for customer edge routers. 1014 Further recommendations on router-specific functionality can be found 1015 in [I-D.ietf-v6ops-ipv6rtr-reqs]. 1017 14.1. IPv6 Router Alert Option - RFC 2711 1019 The IPv6 Router Alert Option [RFC2711] is an optional IPv6 Hop-by-Hop 1020 Header that is used in conjunction with some protocols (e.g., RSVP 1021 [RFC2205] or Multicast Listener Discovery (MLDv2) [RFC3810]). The 1022 Router Alert option will need to be implemented whenever such 1023 protocols that mandate its use are implemented. See Section 5.11. 1025 14.2. Neighbor Discovery for IPv6 - RFC 4861 1027 Sending Router Advertisements and processing Router Solicitations 1028 MUST be supported. 1030 Section 7 of [RFC6275] includes some mobility-specific extensions to 1031 Neighbor Discovery. Routers SHOULD implement Sections 7.3 and 7.5, 1032 even if they do not implement Home Agent functionality. 1034 14.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 1036 A single DHCP server ([RFC3315] or [RFC4862]) can provide 1037 configuration information to devices directly attached to a shared 1038 link, as well as to devices located elsewhere within a site. 1039 Communication between a client and a DHCP server located on different 1040 links requires the use of DHCP relay agents on routers. 1042 In simple deployments, consisting of a single router and either a 1043 single LAN or multiple LANs attached to the single router, together 1044 with a WAN connection, a DHCP server embedded within the router is 1045 one common deployment scenario (e.g., [RFC7084]). There is no need 1046 for relay agents in such scenarios. 1048 In more complex deployment scenarios, such as within enterprise or 1049 service provider networks, the use of DHCP requires some level of 1050 configuration, in order to configure relay agents, DHCP servers, etc. 1051 In such environments, the DHCP server might even be run on a 1052 traditional server, rather than as part of a router. 1054 Because of the wide range of deployment scenarios, support for DHCP 1055 server functionality on routers is optional. However, routers 1056 targeted for deployment within more complex scenarios (as described 1057 above) SHOULD support relay agent functionality. Note that "Basic 1058 Requirements for IPv6 Customer Edge Routers" [RFC7084] requires 1059 implementation of a DHCPv6 server function in IPv6 Customer Edge (CE) 1060 routers. 1062 14.4. IPv6 Prefix Length Recommendation for Forwarding - BCP 198 1064 Forwarding nodes MUST conform to BCP 198 [RFC7608] and thus IPv6 1065 implementations of nodes that may forward packets MUST conform to the 1066 rules specified in Section 5.1 of [RFC4632]. 1068 15. Constrained Devices 1070 The target for this document is general IPv6 nodes. In this Section, 1071 we briefly discuss considerations for constrained devices. 1073 In the case of constrained nodes, with limited CPU, memory, bandwidth 1074 or power, support for certain IPv6 functionality may need to be 1075 considered due to those limitations. While the requirements of this 1076 document are RECOMMENDED for all nodes, including constrained nodes, 1077 compromises may need to be made in certain cases. Where such 1078 compromises are made, the interoperability of devices should be 1079 strongly considered, paticularly where this may impact other nodes on 1080 the same link, e.g., only supporting MLDv1 will affect other nodes. 1082 The IETF 6LowPAN (IPv6 over Low Power LWPAN) WG defined six RFCs, 1083 including a general overview and problem statement ([RFC4919], the 1084 means by which IPv6 packets are transmitted over IEEE 802.15.4 1085 networks [RFC4944] and ND optimisations for that medium [RFC6775]. 1087 If an IPv6 node is concerned about the impact of IPv6 message power 1088 consumption, it SHOULD want to implement the recommendations in 1089 [RFC7772]. 1091 16. Network Management 1093 Network management MAY be supported by IPv6 nodes. However, for IPv6 1094 nodes that are embedded devices, network management may be the only 1095 possible way of controlling these nodes. 1097 Existing network management protocols include SNMP [RFC3411], NETCONF 1098 [RFC6241] and RESTCONF [RFC8040]. 1100 16.1. Management Information Base (MIB) Modules 1102 [RFC8096] clarifies the obsoleted status of various IPv6-specific MIB 1103 modules. 1105 The following two MIB modules SHOULD be supported by nodes that 1106 support a Simple Network Management Protocol (SNMP) agent. 1108 16.1.1. IP Forwarding Table MIB 1110 The IP Forwarding Table MIB [RFC4292] SHOULD be supported by nodes 1111 that support an SNMP agent. 1113 16.1.2. Management Information Base for the Internet Protocol (IP) 1115 The IP MIB [RFC4293] SHOULD be supported by nodes that support an 1116 SNMP agent. 1118 16.1.3. Interface MIB 1120 The Interface MIB [RFC2863] SHOULD be supported by nodes the support 1121 an SNMP agent. 1123 16.2. YANG Data Models 1125 The following YANG data models SHOULD be supported by nodes that 1126 support a NETCONF or RESTCONF agent. 1128 16.2.1. IP Management YANG Model 1130 The IP Management YANG Model [I-D.ietf-netmod-rfc7277bis] SHOULD be 1131 supported by nodes that support NETCONF or RESTCONF. 1133 16.2.2. Interface Management YANG Model 1135 The Interface Management YANG Model [I-D.ietf-netmod-rfc7223bis] 1136 SHOULD be supported by nodes that support NETCONF or RESTCONF. 1138 17. Security Considerations 1140 This document does not directly affect the security of the Internet, 1141 beyond the security considerations associated with the individual 1142 protocols. 1144 Security is also discussed in Section 13 above. 1146 18. IANA Considerations 1148 This document does not require any IANA actions. 1150 19. Authors and Acknowledgments 1152 19.1. Authors and Acknowledgments (Current Document) 1154 For this version of the IPv6 Node Requirements document, the authors 1155 would like to thank Brian Carpenter, Dave Thaler, Tom Herbert, Erik 1156 Kline, Mohamed Boucadair, and Michayla Newcombe for their 1157 contributions. 1159 19.2. Authors and Acknowledgments from RFC 6434 1161 Ed Jankiewicz and Thomas Narten were named authors of the previous 1162 iteration of this document, RFC6434. 1164 For this version of the document, the authors thanked Hitoshi Asaeda, 1165 Brian Carpenter, Tim Chown, Ralph Droms, Sheila Frankel, Sam Hartman, 1166 Bob Hinden, Paul Hoffman, Pekka Savola, Yaron Sheffer, and Dave 1167 Thaler. 1169 19.3. Authors and Acknowledgments from RFC 4294 1171 The original version of this document (RFC 4294) was written by the 1172 IPv6 Node Requirements design team, which had the following members: 1173 Jari Arkko, Marc Blanchet, Samita Chakrabarti, Alain Durand, Gerard 1174 Gastaud, Jun-ichiro Itojun Hagino, Atsushi Inoue, Masahiro Ishiyama, 1175 John Loughney, Rajiv Raghunarayan, Shoichi Sakane, Dave Thaler, and 1176 Juha Wiljakka. 1178 The authors would like to thank Ran Atkinson, Jim Bound, Brian 1179 Carpenter, Ralph Droms, Christian Huitema, Adam Machalek, Thomas 1180 Narten, Juha Ollila, and Pekka Savola for their comments. Thanks to 1181 Mark Andrews for comments and corrections on DNS text. Thanks to 1182 Alfred Hoenes for tracking the updates to various RFCs. 1184 20. Appendix: Changes from RFC 6434 1186 There have been many editorial clarifications as well as significant 1187 additions and updates. While this section highlights some of the 1188 changes, readers should not rely on this section for a comprehensive 1189 list of all changes. 1191 1. Restructured sections 1193 2. Added 6LoWPAN to link layers as it has some deployment. 1195 3. Removed DOD IPv6 Profile as it hasn't been updated. 1197 4. Updated to MLDv2 support to a MUST since nodes are restricted if 1198 MLDv1 is used. 1200 5. Require DNS RA Options so SLAAC-only devices can get DNS, 1201 RFC8106 is a MUST. 1203 6. Require RFC3646 DNS Options for DHCPv6 implementations. 1205 7. Added RESTCONF and NETCONF as possible options to Network 1206 management. 1208 8. Added section on constrained devices. 1210 9. Added text on RFC7934, address availability to hosts (SHOULD). 1212 10. Added text on RFC7844, anonymity profiles for DHCPv6 clients. 1214 11. mDNS and DNS-SD added as updated service discovery. 1216 12. Added RFC8028 as a SHOULD as a method for solving multi-prefix 1217 network 1219 13. Added ECN RFC3168 as a SHOULD, since recent reports have shown 1220 this as useful, and added a note on RFC8311, which is related. 1222 14. Added reference to RFC7123 for Security over IPv4-only networks 1224 15. Removed Jumbograms RFC2675 as they aren't deployed. 1226 16. Updated Obseleted RFCs to the new version of the RFC including 1227 2460, 1981, 7321, 4307 1229 17. Added RFC7772 for power comsumptions considerations 1231 18. Added why /64 boundries for more detail - RFC 7421 1233 19. Added a Unique IPv6 Prefix per Host to support currently 1234 deployed IPv6 networks 1236 20. Clarified RFC7066 was snapshot for 3GPP 1238 21. Updated 4191 as a MUST, SHOULD for Type C Host as it helps solve 1239 multi-prefix problem 1241 22. Removed IPv6 over ATM since there aren't many deployments 1242 23. Added a note in Section 6.6 for RFC6724 Section 5.5/ 1244 24. Added MUST for BCP 198 for forwarding IPv6 packets 1246 25. Added reference to draft-ietf-v6ops-ipv6rtr-reqs as it has more 1247 recommendations for a Router 1249 26. Added reference to RFC8064 for stable address creation. 1251 27. Added text on protection from excessive EH options 1253 28. Added text on dangers of 1280 MTU UDP, esp. wrt DNS traffic 1255 29. Added text to clarify RFC8200 behaviour for unrecognized EHs or 1256 unrecognized ULPs 1258 30. Removed dated email addresses from design team acknowledgements 1259 for RFC 4294. 1261 21. Appendix: Changes from RFC 4294 1263 There have been many editorial clarifications as well as significant 1264 additions and updates. While this section highlights some of the 1265 changes, readers should not rely on this section for a comprehensive 1266 list of all changes. 1268 1. Updated the Introduction to indicate that this document is an 1269 applicability statement and is aimed at general nodes. 1271 2. Significantly updated the section on Mobility protocols, adding 1272 references and downgrading previous SHOULDs to MAYs. 1274 3. Changed Sub-IP Layer section to just list relevant RFCs, and 1275 added some more RFCs. 1277 4. Added section on SEND (it is a MAY). 1279 5. Revised section on Privacy Extensions [RFC4941] to add more 1280 nuance to recommendation. 1282 6. Completely revised IPsec/IKEv2 section, downgrading overall 1283 recommendation to a SHOULD. 1285 7. Upgraded recommendation of DHCPv6 to SHOULD. 1287 8. Added background section on DHCP versus RA options, added SHOULD 1288 recommendation for DNS configuration via RAs (RFC6106), and 1289 cleaned up DHCP recommendations. 1291 9. Added recommendation that routers implement Sections 7.3 and 7.5 1292 of [RFC6275]. 1294 10. Added pointer to subnet clarification document [RFC5942]. 1296 11. Added text that "IPv6 Host-to-Router Load Sharing" [RFC4311] 1297 SHOULD be implemented. 1299 12. Added reference to [RFC5722] (Overlapping Fragments), and made 1300 it a MUST to implement. 1302 13. Made "A Recommendation for IPv6 Address Text Representation" 1303 [RFC5952] a SHOULD. 1305 14. Removed mention of "DNAME" from the discussion about [RFC3363]. 1307 15. Numerous updates to reflect newer versions of IPv6 documents, 1308 including [RFC4443], [RFC4291], [RFC3596], and [RFC4213]. 1310 16. Removed discussion of "Managed" and "Other" flags in RAs. There 1311 is no consensus at present on how to process these flags, and 1312 discussion of their semantics was removed in the most recent 1313 update of Stateless Address Autoconfiguration [RFC4862]. 1315 17. Added many more references to optional IPv6 documents. 1317 18. Made "A Recommendation for IPv6 Address Text Representation" 1318 [RFC5952] a SHOULD. 1320 19. Added reference to [RFC5722] (Overlapping Fragments), and made 1321 it a MUST to implement. 1323 20. Updated MLD section to include reference to Lightweight MLD 1324 [RFC5790]. 1326 21. Added SHOULD recommendation for "Default Router Preferences and 1327 More-Specific Routes" [RFC4191]. 1329 22. Made "IPv6 Flow Label Specification" [RFC6437] a SHOULD. 1331 22. References 1333 22.1. Normative References 1335 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1336 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1337 . 1339 [RFC1035] Mockapetris, P., "Domain names - implementation and 1340 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1341 November 1987, . 1343 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1344 Requirement Levels", BCP 14, RFC 2119, 1345 DOI 10.17487/RFC2119, March 1997, 1346 . 1348 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1349 Listener Discovery (MLD) for IPv6", RFC 2710, 1350 DOI 10.17487/RFC2710, October 1999, 1351 . 1353 [RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", 1354 RFC 2711, DOI 10.17487/RFC2711, October 1999, 1355 . 1357 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 1358 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 1359 . 1361 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 1362 of Explicit Congestion Notification (ECN) to IP", 1363 RFC 3168, DOI 10.17487/RFC3168, September 2001, 1364 . 1366 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1367 C., and M. Carney, "Dynamic Host Configuration Protocol 1368 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1369 2003, . 1371 [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An 1372 Architecture for Describing Simple Network Management 1373 Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, 1374 DOI 10.17487/RFC3411, December 2002, 1375 . 1377 [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 1378 "DNS Extensions to Support IP Version 6", STD 88, 1379 RFC 3596, DOI 10.17487/RFC3596, October 2003, 1380 . 1382 [RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol 1383 (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736, 1384 April 2004, . 1386 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1387 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1388 DOI 10.17487/RFC3810, June 2004, 1389 . 1391 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1392 Rose, "DNS Security Introduction and Requirements", 1393 RFC 4033, DOI 10.17487/RFC4033, March 2005, 1394 . 1396 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1397 Rose, "Resource Records for the DNS Security Extensions", 1398 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1399 . 1401 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1402 Rose, "Protocol Modifications for the DNS Security 1403 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, 1404 . 1406 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1407 for IPv6 Hosts and Routers", RFC 4213, 1408 DOI 10.17487/RFC4213, October 2005, 1409 . 1411 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1412 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1413 2006, . 1415 [RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, 1416 DOI 10.17487/RFC4292, April 2006, 1417 . 1419 [RFC4293] Routhier, S., Ed., "Management Information Base for the 1420 Internet Protocol (IP)", RFC 4293, DOI 10.17487/RFC4293, 1421 April 2006, . 1423 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1424 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 1425 December 2005, . 1427 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1428 RFC 4303, DOI 10.17487/RFC4303, December 2005, 1429 . 1431 [RFC4311] Hinden, R. and D. Thaler, "IPv6 Host-to-Router Load 1432 Sharing", RFC 4311, DOI 10.17487/RFC4311, November 2005, 1433 . 1435 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1436 Control Message Protocol (ICMPv6) for the Internet 1437 Protocol Version 6 (IPv6) Specification", STD 89, 1438 RFC 4443, DOI 10.17487/RFC4443, March 2006, 1439 . 1441 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 1442 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 1443 . 1445 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 1446 (CIDR): The Internet Address Assignment and Aggregation 1447 Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August 1448 2006, . 1450 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1451 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1452 DOI 10.17487/RFC4861, September 2007, 1453 . 1455 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1456 Address Autoconfiguration", RFC 4862, 1457 DOI 10.17487/RFC4862, September 2007, 1458 . 1460 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1461 Extensions for Stateless Address Autoconfiguration in 1462 IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, 1463 . 1465 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 1466 of Type 0 Routing Headers in IPv6", RFC 5095, 1467 DOI 10.17487/RFC5095, December 2007, 1468 . 1470 [RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers", 1471 RFC 5453, DOI 10.17487/RFC5453, February 2009, 1472 . 1474 [RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", 1475 RFC 5722, DOI 10.17487/RFC5722, December 2009, 1476 . 1478 [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 1479 Group Management Protocol Version 3 (IGMPv3) and Multicast 1480 Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, 1481 DOI 10.17487/RFC5790, February 2010, 1482 . 1484 [RFC5942] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet 1485 Model: The Relationship between Links and Subnet 1486 Prefixes", RFC 5942, DOI 10.17487/RFC5942, July 2010, 1487 . 1489 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 1490 Address Text Representation", RFC 5952, 1491 DOI 10.17487/RFC5952, August 2010, 1492 . 1494 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 1495 and A. Bierman, Ed., "Network Configuration Protocol 1496 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 1497 . 1499 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 1500 "IPv6 Flow Label Specification", RFC 6437, 1501 DOI 10.17487/RFC6437, November 2011, 1502 . 1504 [RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and 1505 M. Bhatia, "A Uniform Format for IPv6 Extension Headers", 1506 RFC 6564, DOI 10.17487/RFC6564, April 2012, 1507 . 1509 [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, 1510 "Default Address Selection for Internet Protocol Version 6 1511 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, 1512 . 1514 [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, 1515 DOI 10.17487/RFC6762, February 2013, 1516 . 1518 [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service 1519 Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, 1520 . 1522 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1523 Bormann, "Neighbor Discovery Optimization for IPv6 over 1524 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1525 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1526 . 1528 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 1529 for DNS (EDNS(0))", STD 75, RFC 6891, 1530 DOI 10.17487/RFC6891, April 2013, 1531 . 1533 [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", 1534 RFC 6946, DOI 10.17487/RFC6946, May 2013, 1535 . 1537 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 1538 of IPv6 Extension Headers", RFC 7045, 1539 DOI 10.17487/RFC7045, December 2013, 1540 . 1542 [RFC7048] Nordmark, E. and I. Gashinsky, "Neighbor Unreachability 1543 Detection Is Too Impatient", RFC 7048, 1544 DOI 10.17487/RFC7048, January 2014, 1545 . 1547 [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of 1548 Oversized IPv6 Header Chains", RFC 7112, 1549 DOI 10.17487/RFC7112, January 2014, 1550 . 1552 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 1553 Interface Identifiers with IPv6 Stateless Address 1554 Autoconfiguration (SLAAC)", RFC 7217, 1555 DOI 10.17487/RFC7217, April 2014, 1556 . 1558 [I-D.ietf-netmod-rfc7223bis] 1559 Bjorklund, M., "A YANG Data Model for Interface 1560 Management", draft-ietf-netmod-rfc7223bis-03 (work in 1561 progress), January 2018. 1563 [I-D.ietf-netmod-rfc7277bis] 1564 Bjorklund, M., "A YANG Data Model for IP Management", 1565 draft-ietf-netmod-rfc7277bis-03 (work in progress), 1566 January 2018. 1568 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1569 Kivinen, "Internet Key Exchange Protocol Version 2 1570 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 1571 2014, . 1573 [RFC7527] Asati, R., Singh, H., Beebee, W., Pignataro, C., Dart, E., 1574 and W. George, "Enhanced Duplicate Address Detection", 1575 RFC 7527, DOI 10.17487/RFC7527, April 2015, 1576 . 1578 [RFC7559] Krishnan, S., Anipko, D., and D. Thaler, "Packet-Loss 1579 Resiliency for Router Solicitations", RFC 7559, 1580 DOI 10.17487/RFC7559, May 2015, 1581 . 1583 [RFC7608] Boucadair, M., Petrescu, A., and F. Baker, "IPv6 Prefix 1584 Length Recommendation for Forwarding", BCP 198, RFC 7608, 1585 DOI 10.17487/RFC7608, July 2015, 1586 . 1588 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 1589 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 1590 February 2016, . 1592 [RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6 1593 Atomic Fragments Considered Harmful", RFC 8021, 1594 DOI 10.17487/RFC8021, January 2017, 1595 . 1597 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 1598 Hosts in a Multi-Prefix Network", RFC 8028, 1599 DOI 10.17487/RFC8028, November 2016, 1600 . 1602 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 1603 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 1604 . 1606 [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, 1607 "Recommendation on Stable IPv6 Interface Identifiers", 1608 RFC 8064, DOI 10.17487/RFC8064, February 2017, 1609 . 1611 [RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 1612 "IPv6 Router Advertisement Options for DNS Configuration", 1613 RFC 8106, DOI 10.17487/RFC8106, March 2017, 1614 . 1616 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1617 (IPv6) Specification", STD 86, RFC 8200, 1618 DOI 10.17487/RFC8200, July 2017, 1619 . 1621 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1622 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1623 DOI 10.17487/RFC8201, July 2017, 1624 . 1626 [RFC8221] Wouters, P., Migault, D., Mattsson, J., Nir, Y., and T. 1627 Kivinen, "Cryptographic Algorithm Implementation 1628 Requirements and Usage Guidance for Encapsulating Security 1629 Payload (ESP) and Authentication Header (AH)", RFC 8221, 1630 DOI 10.17487/RFC8221, October 2017, 1631 . 1633 [RFC8247] Nir, Y., Kivinen, T., Wouters, P., and D. Migault, 1634 "Algorithm Implementation Requirements and Usage Guidance 1635 for the Internet Key Exchange Protocol Version 2 (IKEv2)", 1636 RFC 8247, DOI 10.17487/RFC8247, September 2017, 1637 . 1639 [RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion 1640 Notification (ECN) Experimentation", RFC 8311, 1641 DOI 10.17487/RFC8311, January 2018, 1642 . 1644 22.2. Informative References 1646 [I-D.ietf-v6ops-ipv6rtr-reqs] 1647 Kahn, Z., Brzozowski, J., and R. White, "Requirements for 1648 IPv6 Routers", draft-ietf-v6ops-ipv6rtr-reqs-01 (work in 1649 progress), January 2018. 1651 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 1652 RFC 793, DOI 10.17487/RFC0793, September 1981, 1653 . 1655 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 1656 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 1657 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 1658 September 1997, . 1660 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1661 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1662 . 1664 [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 1665 over Non-Broadcast Multiple Access (NBMA) networks", 1666 RFC 2491, DOI 10.17487/RFC2491, January 1999, 1667 . 1669 [RFC2590] Conta, A., Malis, A., and M. Mueller, "Transmission of 1670 IPv6 Packets over Frame Relay Networks Specification", 1671 RFC 2590, DOI 10.17487/RFC2590, May 1999, 1672 . 1674 [RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", 1675 RFC 2923, DOI 10.17487/RFC2923, September 2000, 1676 . 1678 [RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets 1679 over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146, 1680 October 2001, . 1682 [RFC3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. 1683 Hain, "Representing Internet Protocol version 6 (IPv6) 1684 Addresses in the Domain Name System (DNS)", RFC 3363, 1685 DOI 10.17487/RFC3363, August 2002, 1686 . 1688 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 1689 Stevens, "Basic Socket Interface Extensions for IPv6", 1690 RFC 3493, DOI 10.17487/RFC3493, February 2003, 1691 . 1693 [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, 1694 "Advanced Sockets Application Program Interface (API) for 1695 IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003, 1696 . 1698 [RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic 1699 Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, 1700 DOI 10.17487/RFC3646, December 2003, 1701 . 1703 [RFC3678] Thaler, D., Fenner, B., and B. Quinn, "Socket Interface 1704 Extensions for Multicast Source Filters", RFC 3678, 1705 DOI 10.17487/RFC3678, January 2004, 1706 . 1708 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1709 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1710 2011, . 1712 [RFC3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to 1713 Protect Mobile IPv6 Signaling Between Mobile Nodes and 1714 Home Agents", RFC 3776, DOI 10.17487/RFC3776, June 2004, 1715 . 1717 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 1718 "SEcure Neighbor Discovery (SEND)", RFC 3971, 1719 DOI 10.17487/RFC3971, March 2005, 1720 . 1722 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 1723 RFC 3972, DOI 10.17487/RFC3972, March 2005, 1724 . 1726 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 1727 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 1728 November 2005, . 1730 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 1731 DOI 10.17487/RFC4302, December 2005, 1732 . 1734 [RFC4338] DeSanti, C., Carlson, C., and R. Nixon, "Transmission of 1735 IPv6, IPv4, and Address Resolution Protocol (ARP) Packets 1736 over Fibre Channel", RFC 4338, DOI 10.17487/RFC4338, 1737 January 2006, . 1739 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 1740 Network Address Translations (NATs)", RFC 4380, 1741 DOI 10.17487/RFC4380, February 2006, 1742 . 1744 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1745 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1746 . 1748 [RFC4584] Chakrabarti, S. and E. Nordmark, "Extension to Sockets API 1749 for Mobile IPv6", RFC 4584, DOI 10.17487/RFC4584, July 1750 2006, . 1752 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 1753 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 1754 . 1756 [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 1757 IKEv2 and the Revised IPsec Architecture", RFC 4877, 1758 DOI 10.17487/RFC4877, April 2007, 1759 . 1761 [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, 1762 "Extended ICMP to Support Multi-Part Messages", RFC 4884, 1763 DOI 10.17487/RFC4884, April 2007, 1764 . 1766 [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering 1767 ICMPv6 Messages in Firewalls", RFC 4890, 1768 DOI 10.17487/RFC4890, May 2007, 1769 . 1771 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 1772 over Low-Power Wireless Personal Area Networks (6LoWPANs): 1773 Overview, Assumptions, Problem Statement, and Goals", 1774 RFC 4919, DOI 10.17487/RFC4919, August 2007, 1775 . 1777 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 1778 "Transmission of IPv6 Packets over IEEE 802.15.4 1779 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 1780 . 1782 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 1783 Socket API for Source Address Selection", RFC 5014, 1784 DOI 10.17487/RFC5014, September 2007, 1785 . 1787 [RFC5072] Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6 1788 over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007, 1789 . 1791 [RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S. 1792 Madanapalli, "Transmission of IPv6 via the IPv6 1793 Convergence Sublayer over IEEE 802.16 Networks", RFC 5121, 1794 DOI 10.17487/RFC5121, February 2008, 1795 . 1797 [RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack 1798 Hosts and Routers", RFC 5555, DOI 10.17487/RFC5555, June 1799 2009, . 1801 [RFC6563] Jiang, S., Conrad, D., and B. Carpenter, "Moving A6 to 1802 Historic Status", RFC 6563, DOI 10.17487/RFC6563, March 1803 2012, . 1805 [RFC7066] Korhonen, J., Ed., Arkko, J., Ed., Savolainen, T., and S. 1806 Krishnan, "IPv6 for Third Generation Partnership Project 1807 (3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066, 1808 November 2013, . 1810 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1811 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1812 DOI 10.17487/RFC7084, November 2013, 1813 . 1815 [RFC7123] Gont, F. and W. Liu, "Security Implications of IPv6 on 1816 IPv4 Networks", RFC 7123, DOI 10.17487/RFC7123, February 1817 2014, . 1819 [RFC7278] Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6 1820 /64 Prefix from a Third Generation Partnership Project 1821 (3GPP) Mobile Interface to a LAN Link", RFC 7278, 1822 DOI 10.17487/RFC7278, June 2014, 1823 . 1825 [RFC7371] Boucadair, M. and S. Venaas, "Updates to the IPv6 1826 Multicast Addressing Architecture", RFC 7371, 1827 DOI 10.17487/RFC7371, September 2014, 1828 . 1830 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1831 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1832 Boundary in IPv6 Addressing", RFC 7421, 1833 DOI 10.17487/RFC7421, January 2015, 1834 . 1836 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 1837 Considerations for IPv6 Address Generation Mechanisms", 1838 RFC 7721, DOI 10.17487/RFC7721, March 2016, 1839 . 1841 [RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy 1842 Consumption of Router Advertisements", BCP 202, RFC 7772, 1843 DOI 10.17487/RFC7772, February 2016, 1844 . 1846 [RFC7844] Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity 1847 Profiles for DHCP Clients", RFC 7844, 1848 DOI 10.17487/RFC7844, May 2016, 1849 . 1851 [RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi, 1852 "Host Address Availability Recommendations", BCP 204, 1853 RFC 7934, DOI 10.17487/RFC7934, July 2016, 1854 . 1856 [RFC8096] Fenner, B., "The IPv6-Specific MIB Modules Are Obsolete", 1857 RFC 8096, DOI 10.17487/RFC8096, April 2017, 1858 . 1860 [RFC8273] Brzozowski, J. and G. Van de Velde, "Unique IPv6 Prefix 1861 per Host", RFC 8273, DOI 10.17487/RFC8273, December 2017, 1862 . 1864 [POSIX] IEEE, "IEEE Std. 1003.1-2008 Standard for Information 1865 Technology -- Portable Operating System Interface (POSIX), 1866 ISO/IEC 9945:2009", . 1868 [USGv6] National Institute of Standards and Technology, "A Profile 1869 for IPv6 in the U.S. Government - Version 1.0", July 2008, 1870 . 1872 Authors' Addresses 1874 Tim Chown 1875 Jisc 1876 Lumen House, Library Avenue 1877 Harwell Oxford, Didcot OX11 0SG 1878 United Kingdom 1880 Email: tim.chown@jisc.ac.uk 1882 John Loughney 1883 Intel 1884 Santa Clara, CA 1885 USA 1887 Email: john.loughney@gmail.com 1889 Timothy Winters 1890 University of New Hampshire, Interoperability Lab (UNH-IOL) 1891 Durham, NH 1892 United States 1894 Email: twinters@iol.unh.edu