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Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 3736 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 4941 (Obsoleted by RFC 8981) ** Downref: Normative reference to an Informational RFC: RFC 7739 ** Downref: Normative reference to an Informational RFC: RFC 8021 -- Obsolete informational reference (is this intentional?): RFC 793 (Obsoleted by RFC 9293) Summary: 5 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). 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 20, 2018 T. Winters 7 UNH-IOL 8 March 19, 2018 10 IPv6 Node Requirements 11 draft-ietf-6man-rfc6434-bis-08 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 20, 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 . . . . . . . 23 117 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 . . . . . . . . . . . . . . . . . . . . . 24 126 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 To mitigate a variety of potential attacks, nodes SHOULD avoid using 293 predictable fragment Identification values in Fragment Headers, as 294 discussed in [RFC7739]. 296 All nodes SHOULD support the setting and use of the IPv6 Flow Label 297 field as defined in the IPv6 Flow Label specification [RFC6437]. 298 Forwarding nodes such as routers and load distributors MUST NOT 299 depend only on Flow Label values being uniformly distributed. It is 300 RECOMMENDED that source hosts support the flow label by setting the 301 Flow Label field for all packets of a given flow to the same value 302 chosen from an approximation to a discrete uniform distribution. 304 5.2. Support for IPv6 Extension Headers 306 RFC 8200 specifies extension headers and the processing for these 307 headers. 309 Extension headers (except for the Hop-by-Hop Options header) are not 310 processed, inserted, or deleted by any node along a packet's delivery 311 path, until the packet reaches the node (or each of the set of nodes, 312 in the case of multicast) identified in the Destination Address field 313 of the IPv6 header. 315 Any unrecognized extension headers or options MUST be processed as 316 described in RFC 8200. Note that where Section 4 of RFC 8200 refers 317 to the action to be taken when a Next Header value in the current 318 header is not recognized by a node, that action applies whether the 319 value is an unrecognized Extension Header or an unrecognized upper 320 layer protocol (ULP). 322 An IPv6 node MUST be able to process these headers. An exception is 323 Routing Header type 0 (RH0), which was deprecated by [RFC5095] due to 324 security concerns and which MUST be treated as an unrecognized 325 routing type. 327 Further, [RFC7045] adds specific requirements for processing of 328 Extension Headers, in particular that any forwarding node along an 329 IPv6 packet's path, which forwards the packet for any reason, SHOULD 330 do so regardless of any extension headers that are present. 332 As per RFC 8200, when a node fragments an IPv6 datagram, it MUST 333 include the entire IPv6 Header Chain in the first fragment. The Per- 334 Fragment headers must consist of the IPv6 header plus any extension 335 headers that must be processed by nodes en route to the destination, 336 that is, all headers up to and including the Routing header if 337 present, else the Hop-by-Hop Options header if present, else no 338 extension headers. On reassembly, if the first fragment does not 339 include all headers through an Upper-Layer header, then that fragment 340 should be discarded and an ICMP Parameter Problem, Code 3, message 341 should be sent to the source of the fragment, with the Pointer field 342 set to zero. See [RFC7112] for a discussion of why oversized IPv6 343 Extension Header chains are avoided. 345 Defining new IPv6 extension headers is not recommended, unless there 346 are no existing IPv6 extension headers that can be used by specifying 347 a new option for that IPv6 extension header. A proposal to specify a 348 new IPv6 extension header must include a detailed technical 349 explanation of why an existing IPv6 extension header can not be used 350 for the desired new function, and in such cases need to follow the 351 format described in Section 8 of RFC 8200. For further background 352 reading on this topic, see [RFC6564]. 354 5.3. Protecting a node from excessive EH options 356 As per RFC 8200, end hosts are expected to process all extension 357 headers, destination options, and hop-by-hop options in a packet. 358 Given that the only limit on the number and size of extension headers 359 is the MTU, the processing of received packets could be considerable. 360 It is also conceivable that a long chain of extension headers might 361 be used as a form of denial-of-service attack. Accordingly, a host 362 may place limits on the number and sizes of extension headers and 363 options it is willing to process. 365 A host MAY limit the number of consecutive PAD1 options in 366 destination options or hop-by-hop options to seven. In this case, if 367 the more than seven consecutive PAD1 options are present the packet 368 should be silently discarded. The rationale is that if padding of 369 eight or more bytes is required than the PADN option should be used. 371 A host MAY limit number of bytes in a PADN option to be less than 372 eight. In such a case, if a PADN option is present that has a length 373 greater than seven then the packet should be silently discarded. The 374 rationale for this guideline is that the purpose of padding is for 375 alignment and eight bytes is the maximum alignment used in IPv6. 377 A host MAY disallow unknown options in destination options or hop-by- 378 hop options. This should be configurable where the default is to 379 accept unknown options and process them per [RFC8200]. If a packet 380 with unknown options is received and the host is configured to 381 disallow them, then the packet should be silently discarded. 383 A host MAY impose a limit on the maximum number of non-padding 384 options allowed in a destination options and hop-by-hop extension 385 headers. If this feature is supported the maximum number should be 386 configurable and the default value SHOULD be set to eight. The 387 limits for destination options and hop-by-hop options may be 388 separately configurable. If a packet is received and the number of 389 destination or hop-by-hop optines exceeds the limit, then the packet 390 should be silently discarded. 392 A host MAY impose a limit on the maximum length of destination 393 options or hop-by-hop options extension header. This value should be 394 configurable and the default is to accept options of any length. If 395 a packet is received and the length of destination or hop-by-hop 396 options extension header exceeds the length limit, then the packet 397 should be silently discarded. 399 5.4. Neighbor Discovery for IPv6 - RFC 4861 401 Neighbor Discovery is defined in [RFC4861]; the definition was 402 updated by [RFC5942]. Neighbor Discovery SHOULD be supported. RFC 403 4861 states: 405 Unless specified otherwise (in a document that covers operating IP 406 over a particular link type) this document applies to all link 407 types. However, because ND uses link-layer multicast for some of 408 its services, it is possible that on some link types (e.g., Non- 409 Broadcast Multi-Access (NBMA) links), alternative protocols or 410 mechanisms to implement those services will be specified (in the 411 appropriate document covering the operation of IP over a 412 particular link type). The services described in this document 413 that are not directly dependent on multicast, such as Redirects, 414 next-hop determination, Neighbor Unreachability Detection, etc., 415 are expected to be provided as specified in this document. The 416 details of how one uses ND on NBMA links are addressed in 417 [RFC2491]. 419 Some detailed analysis of Neighbor Discovery follows: 421 Router Discovery is how hosts locate routers that reside on an 422 attached link. Hosts MUST support Router Discovery functionality. 424 Prefix Discovery is how hosts discover the set of address prefixes 425 that define which destinations are on-link for an attached link. 426 Hosts MUST support Prefix Discovery. 428 Hosts MUST also implement Neighbor Unreachability Detection (NUD) for 429 all paths between hosts and neighboring nodes. NUD is not required 430 for paths between routers. However, all nodes MUST respond to 431 unicast Neighbor Solicitation (NS) messages. 433 [RFC7048] discusses NUD, in particular cases where it behaves too 434 impatiently. It states that if a node transmits more than a certain 435 number of packets, then it SHOULD use the exponential backoff of the 436 retransmit timer, up to a certain threshold point. 438 Hosts MUST support the sending of Router Solicitations and the 439 receiving of Router Advertisements. The ability to understand 440 individual Router Advertisement options is dependent on supporting 441 the functionality making use of the particular option. 443 [RFC7559] discusses packet loss resliency for Router Solicitations, 444 and requires that nodes MUST use a specific exponential backoff 445 algorithm for RS retransmissions. 447 All nodes MUST support the sending and receiving of Neighbor 448 Solicitation (NS) and Neighbor Advertisement (NA) messages. NS and 449 NA messages are required for Duplicate Address Detection (DAD). 451 Hosts SHOULD support the processing of Redirect functionality. 452 Routers MUST support the sending of Redirects, though not necessarily 453 for every individual packet (e.g., due to rate limiting). Redirects 454 are only useful on networks supporting hosts. In core networks 455 dominated by routers, Redirects are typically disabled. The sending 456 of Redirects SHOULD be disabled by default on backbone routers. They 457 MAY be enabled by default on routers intended to support hosts on 458 edge networks. 460 "IPv6 Host-to-Router Load Sharing" [RFC4311] includes additional 461 recommendations on how to select from a set of available routers. 462 [RFC4311] SHOULD be supported. 464 5.5. SEcure Neighbor Discovery (SEND) - RFC 3971 466 SEND [RFC3971] and Cryptographically Generated Addresses (CGAs) 467 [RFC3972] provide a way to secure the message exchanges of Neighbor 468 Discovery. SEND has the potential to address certain classes of 469 spoofing attacks, but it does not provide specific protection for 470 threats from off-link attackers. 472 There have been relatively few implementations of SEND in common 473 operating systems and platforms since its publication in 2005, and 474 thus deployment experience remains very limited to date. 476 At this time, support for SEND is considered optional. Due to the 477 complexity in deploying SEND, and its heavyweight provisioning, its 478 deployment is only likely to be considered where nodes are operating 479 in a particularly strict security environment. 481 5.6. IPv6 Router Advertisement Flags Option - RFC 5175 483 Router Advertisements include an 8-bit field of single-bit Router 484 Advertisement flags. The Router Advertisement Flags Option extends 485 the number of available flag bits by 48 bits. At the time of this 486 writing, 6 of the original 8 single-bit flags have been assigned, 487 while 2 remain available for future assignment. No flags have been 488 defined that make use of the new option, and thus, strictly speaking, 489 there is no requirement to implement the option today. However, 490 implementations that are able to pass unrecognized options to a 491 higher-level entity that may be able to understand them (e.g., a 492 user-level process using a "raw socket" facility) MAY take steps to 493 handle the option in anticipation of a future usage. 495 5.7. Path MTU Discovery and Packet Size 497 5.7.1. Path MTU Discovery - RFC 8201 499 "Path MTU Discovery for IP version 6" [RFC8201] SHOULD be supported. 500 From [RFC8200]: 502 It is strongly recommended that IPv6 nodes implement Path MTU 503 Discovery [RFC8201], in order to discover and take advantage of 504 path MTUs greater than 1280 octets. However, a minimal IPv6 505 implementation (e.g., in a boot ROM) may simply restrict itself to 506 sending packets no larger than 1280 octets, and omit 507 implementation of Path MTU Discovery. 509 The rules in [RFC8200] and [RFC5722] MUST be followed for packet 510 fragmentation and reassembly. 512 As described in RFC 8201, nodes implementing Path MTU Discovery and 513 sending packets larger than the IPv6 minimum link MTU are susceptible 514 to problematic connectivity if ICMPv6 messages are blocked or not 515 transmitted. For example, this will result in connections that 516 complete the TCP three- way handshake correctly but then hang when 517 data is transferred. This state is referred to as a black-hole 518 connection [RFC2923]. Path MTU Discovery relies on ICMPv6 Packet Too 519 Big (PTB) to determine the MTU of the path (and thus these should not 520 be filtered, as per the recommendation in [RFC4890]). 522 An extension to Path MTU Discovery defined in RFC 8201 can be found 523 in [RFC4821], which defines a method for Packetization Layer Path MTU 524 Discovery (PLPMTUD) designed for use over paths where delivery of 525 ICMPv6 messages to a host is not assured. 527 5.7.2. Minimum MTU considerations 529 While an IPv6 link MTU can be set to 1280 bytes, it is recommended 530 that for IPv6 UDP in particular, which includes DNS operation, the 531 sender use a large MTU if they can, in order to avoid gratuitous 532 fragmentation-caused packet drops. 534 5.8. ICMP for the Internet Protocol Version 6 (IPv6) - RFC 4443 536 ICMPv6 [RFC4443] MUST be supported. "Extended ICMP to Support Multi- 537 Part Messages" [RFC4884] MAY be supported. 539 5.9. Default Router Preferences and More-Specific Routes - RFC 4191 541 "Default Router Preferences and More-Specific Routes" [RFC4191] 542 provides support for nodes attached to multiple (different) networks, 543 each providing routers that advertise themselves as default routers 544 via Router Advertisements. In some scenarios, one router may provide 545 connectivity to destinations the other router does not, and choosing 546 the "wrong" default router can result in reachability failures. In 547 order to resolve this scenario IPv6 Nodes MUST implement [RFC4191] 548 and SHOULD implement the Type C host role defined in RFC4191. 550 5.10. First-Hop Router Selection - RFC 8028 552 In multihomed scenarios, where a host has more than one prefix, each 553 allocated by an upstream network that is assumed to implement BCP 38 554 ingress filtering, the host may have multiple routers to choose from. 556 Hosts that may be deployed in such multihomed environments SHOULD 557 follow the guidance given in [RFC8028]. 559 5.11. Multicast Listener Discovery (MLD) for IPv6 - RFC 3810 561 Nodes that need to join multicast groups MUST support MLDv2 562 [RFC3810]. MLD is needed by any node that is expected to receive and 563 process multicast traffic and in particular MLDv2 is required for 564 support for source-specific multicast (SSM) as per [RFC4607]. 566 Previous versions of this document only required MLDv1 ([RFC2710]) to 567 be implemented on all nodes. Since participation of any MLDv1-only 568 nodes on a link require that all other nodeas on the link then 569 operate in version 1 compatibility mode, the requirement to support 570 MLDv2 on all nodes was upgraded to a MUST. Further, SSM is now the 571 preferred multicast distribution method, rather than ASM. 573 Note that Neighbor Discovery (as used on most link types -- see 574 Section 5.4) depends on multicast and requires that nodes join 575 Solicited Node multicast addresses. 577 5.12. Explicit Congestion Notification (ECN) - RFC 3168 579 An ECN-aware router may set a mark in the IP header in order to 580 signal impending congestion, rather than dropping a packet. The 581 receiver of the packet echoes the congestion indication to the 582 sender, which can then reduce its transmission rate as if it detected 583 a dropped packet. 585 Nodes that may be deployed in environments where they would benefit 586 from such early congestion notification SHOULD implement [RFC3168]. 587 In such cases, the updates presented in [RFC8311] may also be 588 relevant. 590 6. Addressing and Address Configuration 592 6.1. IP Version 6 Addressing Architecture - RFC 4291 594 The IPv6 Addressing Architecture [RFC4291] MUST be supported. 596 The current IPv6 Address Architecture is based on a 64-bit boundary 597 for subnet prefixes. The reasoning behind this decision is 598 documented in [RFC7421]. 600 Implementations MUST also support the Multicast flag updates 601 documented in [RFC7371] 603 6.2. Host Address Availability Recommendations 605 Hosts may be configured with addresses through a variety of methods, 606 including SLAAC, DHCPv6, or manual configuration. 608 [RFC7934] recommends that networks provide general-purpose end hosts 609 with multiple global IPv6 addresses when they attach, and it 610 describes the benefits of and the options for doing so. Routers 611 SHOULD support [RFC7934] for assigning multiple address to a host. 612 Host SHOULD support assigning multiple addresses as described in 613 [RFC7934]. 615 Nodes SHOULD support the capability to be assigned a prefix per host 616 as documented in [RFC8273]. Such an approach can offer improved host 617 isolation and enhanced subscriber management on shared network 618 segments. 620 6.3. IPv6 Stateless Address Autoconfiguration - RFC 4862 622 Hosts MUST support IPv6 Stateless Address Autoconfiguration. It is 623 recommended, as described in [RFC8064], that unless there is a 624 specific requirement for MAC addresses to be embedded in an IID, 625 nodes follow the procedure in [RFC7217] to generate SLAAC-based 626 addresses, rather than using [RFC4862]. Addresses generated through 627 RFC7217 will be the same whenever a given device (re)appears on the 628 same subnet (with a specific IPv6 prefix), but the IID will vary on 629 each subnet visited. 631 Nodes that are routers MUST be able to generate link-local addresses 632 as described in [RFC4862]. 634 From RFC 4862: 636 The autoconfiguration process specified in this document applies 637 only to hosts and not routers. Since host autoconfiguration uses 638 information advertised by routers, routers will need to be 639 configured by some other means. However, it is expected that 640 routers will generate link-local addresses using the mechanism 641 described in this document. In addition, routers are expected to 642 successfully pass the Duplicate Address Detection procedure 643 described in this document on all addresses prior to assigning 644 them to an interface. 646 All nodes MUST implement Duplicate Address Detection. Quoting from 647 Section 5.4 of RFC 4862: 649 Duplicate Address Detection MUST be performed on all unicast 650 addresses prior to assigning them to an interface, regardless of 651 whether they are obtained through stateless autoconfiguration, 652 DHCPv6, or manual configuration, with the following [exceptions 653 noted therein]. 655 "Optimistic Duplicate Address Detection (DAD) for IPv6" [RFC4429] 656 specifies a mechanism to reduce delays associated with generating 657 addresses via Stateless Address Autoconfiguration [RFC4862]. RFC 658 4429 was developed in conjunction with Mobile IPv6 in order to reduce 659 the time needed to acquire and configure addresses as devices quickly 660 move from one network to another, and it is desirable to minimize 661 transition delays. For general purpose devices, RFC 4429 remains 662 optional at this time. 664 [RFC7527] discusses enhanced DAD, and describes an algorithm to 665 automate the detection of looped back IPv6 ND messages used by DAD. 666 Nodes SHOULD implement this behaviour where such detection is 667 beneficial. 669 6.4. Privacy Extensions for Address Configuration in IPv6 - RFC 4941 671 A node using Stateless Address Autoconfiguration [RFC4862] to form a 672 globally unique IPv6 address using its MAC address to generate the 673 IID will see that IID remain the same on any visited network, even 674 though the network prefix part changes. Thus it is possible for 3rd 675 party devices such nodes communicate with to track the activities of 676 the node as it moves around the network. Privacy Extensions for 677 Stateless Address Autoconfiguration [RFC4941] address this concern by 678 allowing nodes to configure an additional temporary address where the 679 IID is effectively randomly generated. Privacy addresses are then 680 used as source addresses for new communications initiated by the 681 node. 683 General issues regarding privacy issues for IPv6 addressing are 684 discussed in [RFC7721]. 686 RFC 4941 SHOULD be supported. In some scenarios, such as dedicated 687 servers in a data center, it provides limited or no benefit, or may 688 complicate network management. Thus devices implementing this 689 specification MUST provide a way for the end user to explicitly 690 enable or disable the use of such temporary addresses. 692 Note that RFC4941 can be used independently of traditional SLAAC, or 693 of RFC7217-based SLAAC. 695 Implementers of RFC 4941 should be aware that certain addresses are 696 reserved and should not be chosen for use as temporary addresses. 697 Consult "Reserved IPv6 Interface Identifiers" [RFC5453] for more 698 details. 700 6.5. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 702 DHCPv6 [RFC3315] can be used to obtain and configure addresses. In 703 general, a network may provide for the configuration of addresses 704 through SLAAC, DHCPv6, or both. There will be a wide range of IPv6 705 deployment models and differences in address assignment requirements, 706 some of which may require DHCPv6 for stateful address assignment. 707 Consequently, all hosts SHOULD implement address configuration via 708 DHCPv6. 710 In the absence of observed Router Advertisement messages, IPv6 nodes 711 MAY initiate DHCP to obtain IPv6 addresses and other configuration 712 information, as described in Section 5.5.2 of [RFC4862]. 714 Where devices are likely to be carried by users and attached to 715 multiple visisted networks, DHCPv6 client anonymity profiles SHOULD 716 be supported as described in [RFC7844] to minimise the disclosure of 717 identifying information. Section 5 of RFC7844 describes operational 718 considerations on the use of such anonymity profiles. 720 6.6. Default Address Selection for IPv6 - RFC 6724 722 IPv6 nodes will invariably have multiple addresses configured 723 simultaneously, and thus will need to choose which addresses to use 724 for which communications. The rules specified in the Default Address 725 Selection for IPv6 [RFC6724] document MUST be implemented. [RFC8028] 726 updates rule 5.5 from [RFC6724]; implementations SHOULD implement 727 this rule. 729 7. DNS 731 DNS is described in [RFC1034], [RFC1035], [RFC3363], and [RFC3596]. 732 Not all nodes will need to resolve names; those that will never need 733 to resolve DNS names do not need to implement resolver functionality. 734 However, the ability to resolve names is a basic infrastructure 735 capability on which applications rely, and most nodes will need to 736 provide support. All nodes SHOULD implement stub-resolver [RFC1034] 737 functionality, as in [RFC1034], Section 5.3.1, with support for: 739 - AAAA type Resource Records [RFC3596]; 741 - reverse addressing in ip6.arpa using PTR records [RFC3596]; 743 - Extension Mechanisms for DNS (EDNS0) [RFC6891] to allow for DNS 744 packet sizes larger than 512 octets. 746 Those nodes are RECOMMENDED to support DNS security extensions 747 [RFC4033] [RFC4034] [RFC4035]. 749 A6 Resource Records, which were only ever defined with Experimental 750 status in [RFC3363], are now classified as Historic, as per 751 [RFC6563]. 753 8. Configuring Non-Address Information 755 8.1. DHCP for Other Configuration Information 757 DHCP [RFC3315] Specifies a mechanism for IPv6 nodes to obtain address 758 configuration information (see Section 6.5) and to obtain additional 759 (non-address) configuration. If a host implementation supports 760 applications or other protocols that require configuration that is 761 only available via DHCP, hosts SHOULD implement DHCP. For 762 specialized devices on which no such configuration need is present, 763 DHCP may not be necessary. 765 An IPv6 node can use the subset of DHCP (described in [RFC3736]) to 766 obtain other configuration information. 768 If an IPv6 node implements DHCP it MUST implement the DNS options 769 [RFC3646] as most deployments will expect these options are 770 available. 772 8.2. Router Advertisements and Default Gateway 774 There is no defined DHCPv6 Gateway option. 776 Nodes using the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 777 are thus expected to determine their default router information and 778 on-link prefix information from received Router Advertisements. 780 8.3. IPv6 Router Advertisement Options for DNS Configuration - RFC 8106 782 Router Advertisement Options have historically been limited to those 783 that are critical to basic IPv6 functionality. Originally, DNS 784 configuration was not included as an RA option, and DHCP was the 785 recommended way to obtain DNS configuration information. Over time, 786 the thinking surrounding such an option has evolved. It is now 787 generally recognized that few nodes can function adequately without 788 having access to a working DNS resolver, and thus a Standards Track 789 document has been published to provide this capability [RFC8106]. 791 Implementations MUST include support for the DNS RA option [RFC8106]. 793 8.4. DHCP Options versus Router Advertisement Options for Host 794 Configuration 796 In IPv6, there are two main protocol mechanisms for propagating 797 configuration information to hosts: Router Advertisements (RAs) and 798 DHCP. RA options have been restricted to those deemed essential for 799 basic network functioning and for which all nodes are configured with 800 exactly the same information. Examples include the Prefix 801 Information Options, the MTU option, etc. On the other hand, DHCP 802 has generally been preferred for configuration of more general 803 parameters and for parameters that may be client-specific. Generally 804 speaking, however, there has been a desire to define only one 805 mechanism for configuring a given option, rather than defining 806 multiple (different) ways of configuring the same information. 808 One issue with having multiple ways of configuring the same 809 information is that interoperability suffers if a host chooses one 810 mechanism but the network operator chooses a different mechanism. 811 For "closed" environments, where the network operator has significant 812 influence over what devices connect to the network and thus what 813 configuration mechanisms they support, the operator may be able to 814 ensure that a particular mechanism is supported by all connected 815 hosts. In more open environments, however, where arbitrary devices 816 may connect (e.g., a WIFI hotspot), problems can arise. To maximize 817 interoperability in such environments, hosts would need to implement 818 multiple configuration mechanisms to ensure interoperability. 820 9. Service Discovery Protocols 822 [RFC6762] and [RFC6763] describe multicast DNS (mDNS) and DNS-Based 823 Service Discovery (DNS-SD) respectively. These protocols, 824 collectively commonly referred to as the 'Bonjour' protocols after 825 their naming by Apple, provide the means for devices to discover 826 services within a local link and, in the absence of a unicast DNS 827 service, to exchange naming information. 829 Where devices are to be deployed in networks where service dicovery 830 would be beneficial, e.g., for users seeking to discover printers or 831 display devices, mDNS and DNS-SD SHOULD be supported. 833 The IETF dnssd WG is defining solutions for DNS-based service 834 discovery in multi-link networks. 836 10. IPv4 Support and Transition 838 IPv6 nodes MAY support IPv4. 840 10.1. Transition Mechanisms 842 10.1.1. Basic Transition Mechanisms for IPv6 Hosts and Routers - RFC 843 4213 845 If an IPv6 node implements dual stack and tunneling, then [RFC4213] 846 MUST be supported. 848 11. Application Support 850 11.1. Textual Representation of IPv6 Addresses - RFC 5952 852 Software that allows users and operators to input IPv6 addresses in 853 text form SHOULD support "A Recommendation for IPv6 Address Text 854 Representation" [RFC5952]. 856 11.2. Application Programming Interfaces (APIs) 858 There are a number of IPv6-related APIs. This document does not 859 mandate the use of any, because the choice of API does not directly 860 relate to on-the-wire behavior of protocols. Implementers, however, 861 would be advised to consider providing a common API or reviewing 862 existing APIs for the type of functionality they provide to 863 applications. 865 "Basic Socket Interface Extensions for IPv6" [RFC3493] provides IPv6 866 functionality used by typical applications. Implementers should note 867 that RFC3493 has been picked up and further standardized by the 868 Portable Operating System Interface (POSIX) [POSIX]. 870 "Advanced Sockets Application Program Interface (API) for IPv6" 871 [RFC3542] provides access to advanced IPv6 features needed by 872 diagnostic and other more specialized applications. 874 "IPv6 Socket API for Source Address Selection" [RFC5014] provides 875 facilities that allow an application to override the default Source 876 Address Selection rules of [RFC6724]. 878 "Socket Interface Extensions for Multicast Source Filters" [RFC3678] 879 provides support for expressing source filters on multicast group 880 memberships. 882 "Extension to Sockets API for Mobile IPv6" [RFC4584] provides 883 application support for accessing and enabling Mobile IPv6 [RFC6275] 884 features. 886 12. Mobility 888 Mobile IPv6 [RFC6275] and associated specifications [RFC3776] 889 [RFC4877] allow a node to change its point of attachment within the 890 Internet, while maintaining (and using) a permanent address. All 891 communication using the permanent address continues to proceed as 892 expected even as the node moves around. The definition of Mobile IP 893 includes requirements for the following types of nodes: 895 - mobile nodes 897 - correspondent nodes with support for route optimization 899 - home agents 901 - all IPv6 routers 903 At the present time, Mobile IP has seen only limited implementation 904 and no significant deployment, partly because it originally assumed 905 an IPv6-only environment rather than a mixed IPv4/IPv6 Internet. 906 Recently, additional work has been done to support mobility in mixed- 907 mode IPv4 and IPv6 networks [RFC5555]. 909 More usage and deployment experience is needed with mobility before 910 any specific approach can be recommended for broad implementation in 911 all hosts and routers. Consequently, [RFC6275], [RFC5555], and 912 associated standards such as [RFC4877] are considered a MAY at this 913 time. 915 IPv6 for 3GPP [RFC7066] lists a snapshot of required IPv6 916 Functionalities at the time the document was published that would 917 need to be implemented, going above and beyond the recommendations in 918 this document. Additionally a 3GPP IPv6 Host MAY implement [RFC7278] 919 for delivering IPv6 prefixes on the LAN link. 921 13. Security 923 This section describes the specification for security for IPv6 nodes. 925 Achieving security in practice is a complex undertaking. Operational 926 procedures, protocols, key distribution mechanisms, certificate 927 management approaches, etc., are all components that impact the level 928 of security actually achieved in practice. More importantly, 929 deficiencies or a poor fit in any one individual component can 930 significantly reduce the overall effectiveness of a particular 931 security approach. 933 IPsec either can provide end-to-end security between nodes or or can 934 provide channel security (for example, via a site-to-site IPsec VPN), 935 making it possible to provide secure communication for all (or a 936 subset of) communication flows at the IP layer between pairs of 937 internet nodes. IPsec has two standard operating modes, Tunnel-mode 938 and Transport-mode. In Tunnel-mode, IPsec provides network-layer 939 security and protects an entire IP packet by encapsulating the 940 orginal IP packet and then pre-pending a new IP header. In 941 Transport-mode, IPsec provides security for the transport-layer (and 942 above) by encapsulating only the transport-layer (and above) portion 943 of the IP packet (i.e., without adding a 2nd IP header). 945 Although IPsec can be used with manual keying in some cases, such 946 usage has limited applicability and is not recommended. 948 A range of security technologies and approaches proliferate today 949 (e.g., IPsec, Transport Layer Security (TLS), Secure SHell (SSH), SSL 950 VPNS, etc.) No one approach has emerged as an ideal technology for 951 all needs and environments. Moreover, IPsec is not viewed as the 952 ideal security technology in all cases and is unlikely to displace 953 the others. 955 Previously, IPv6 mandated implementation of IPsec and recommended the 956 key management approach of IKE. This document updates that 957 recommendation by making support of the IPsec Architecture [RFC4301] 958 a SHOULD for all IPv6 nodes. Note that the IPsec Architecture 959 requires (e.g., Section 4.5 of RFC 4301) the implementation of both 960 manual and automatic key management. Currently, the default 961 automated key management protocol to implement is IKEv2 [RFC7296]. 963 This document recognizes that there exists a range of device types 964 and environments where approaches to security other than IPsec can be 965 justified. For example, special-purpose devices may support only a 966 very limited number or type of applications, and an application- 967 specific security approach may be sufficient for limited management 968 or configuration capabilities. Alternatively, some devices may run 969 on extremely constrained hardware (e.g., sensors) where the full 970 IPsec Architecture is not justified. 972 Because most common platforms now support IPv6 and have it enabled by 973 default, IPv6 security is an issue for networks that are ostensibly 974 IPv4-only; see [RFC7123] for guidance on this area. 976 13.1. Requirements 978 "Security Architecture for the Internet Protocol" [RFC4301] SHOULD be 979 supported by all IPv6 nodes. Note that the IPsec Architecture 980 requires (e.g., Section 4.5 of [RFC4301]) the implementation of both 981 manual and automatic key management. Currently, the default 982 automated key management protocol to implement is IKEv2. As required 983 in [RFC4301], IPv6 nodes implementing the IPsec Architecture MUST 984 implement ESP [RFC4303] and MAY implement AH [RFC4302]. 986 13.2. Transforms and Algorithms 988 The current set of mandatory-to-implement algorithms for the IPsec 989 Architecture are defined in "Cryptographic Algorithm Implementation 990 Requirements For ESP and AH" [RFC8221]. IPv6 nodes implementing the 991 IPsec Architecture MUST conform to the requirements in [RFC8221]. 992 Preferred cryptographic algorithms often change more frequently than 993 security protocols. Therefore, implementations MUST allow for 994 migration to new algorithms, as RFC 8221 is replaced or updated in 995 the future. 997 The current set of mandatory-to-implement algorithms for IKEv2 are 998 defined in "Cryptographic Algorithms for Use in the Internet Key 999 Exchange Version 2 (IKEv2)" [RFC8247]. IPv6 nodes implementing IKEv2 1000 MUST conform to the requirements in [RFC8247] and/or any future 1001 updates or replacements to [RFC8247]. 1003 14. Router-Specific Functionality 1005 This section defines general host considerations for IPv6 nodes that 1006 act as routers. Currently, this section does not discuss detailed 1007 routing-specific requirements. For the case of typical home routers, 1008 [RFC7084] defines basic requirements for customer edge routers. 1010 14.1. IPv6 Router Alert Option - RFC 2711 1012 The IPv6 Router Alert Option [RFC2711] is an optional IPv6 Hop-by-Hop 1013 Header that is used in conjunction with some protocols (e.g., RSVP 1014 [RFC2205] or Multicast Listener Discovery (MLDv2) [RFC3810]). The 1015 Router Alert option will need to be implemented whenever such 1016 protocols that mandate its use are implemented. See Section 5.11. 1018 14.2. Neighbor Discovery for IPv6 - RFC 4861 1020 Sending Router Advertisements and processing Router Solicitations 1021 MUST be supported. 1023 Section 7 of [RFC6275] includes some mobility-specific extensions to 1024 Neighbor Discovery. Routers SHOULD implement Sections 7.3 and 7.5, 1025 even if they do not implement Home Agent functionality. 1027 14.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 1029 A single DHCP server ([RFC3315] or [RFC4862]) can provide 1030 configuration information to devices directly attached to a shared 1031 link, as well as to devices located elsewhere within a site. 1032 Communication between a client and a DHCP server located on different 1033 links requires the use of DHCP relay agents on routers. 1035 In simple deployments, consisting of a single router and either a 1036 single LAN or multiple LANs attached to the single router, together 1037 with a WAN connection, a DHCP server embedded within the router is 1038 one common deployment scenario (e.g., [RFC7084]). There is no need 1039 for relay agents in such scenarios. 1041 In more complex deployment scenarios, such as within enterprise or 1042 service provider networks, the use of DHCP requires some level of 1043 configuration, in order to configure relay agents, DHCP servers, etc. 1044 In such environments, the DHCP server might even be run on a 1045 traditional server, rather than as part of a router. 1047 Because of the wide range of deployment scenarios, support for DHCP 1048 server functionality on routers is optional. However, routers 1049 targeted for deployment within more complex scenarios (as described 1050 above) SHOULD support relay agent functionality. Note that "Basic 1051 Requirements for IPv6 Customer Edge Routers" [RFC7084] requires 1052 implementation of a DHCPv6 server function in IPv6 Customer Edge (CE) 1053 routers. 1055 14.4. IPv6 Prefix Length Recommendation for Forwarding - BCP 198 1057 Forwarding nodes MUST conform to BCP 198 [RFC7608] and thus IPv6 1058 implementations of nodes that may forward packets MUST conform to the 1059 rules specified in Section 5.1 of [RFC4632]. 1061 15. Constrained Devices 1063 The target for this document is general IPv6 nodes. In this Section, 1064 we briefly discuss considerations for constrained devices. 1066 In the case of constrained nodes, with limited CPU, memory, bandwidth 1067 or power, support for certain IPv6 functionality may need to be 1068 considered due to those limitations. While the requirements of this 1069 document are RECOMMENDED for all nodes, including constrained nodes, 1070 compromises may need to be made in certain cases. Where such 1071 compromises are made, the interoperability of devices should be 1072 strongly considered, paticularly where this may impact other nodes on 1073 the same link, e.g., only supporting MLDv1 will affect other nodes. 1075 The IETF 6LowPAN (IPv6 over Low Power LWPAN) WG defined six RFCs, 1076 including a general overview and problem statement ([RFC4919], the 1077 means by which IPv6 packets are transmitted over IEEE 802.15.4 1078 networks [RFC4944] and ND optimisations for that medium [RFC6775]. 1080 If an IPv6 node is concerned about the impact of IPv6 message power 1081 consumption, it SHOULD want to implement the recommendations in 1082 [RFC7772]. 1084 16. Network Management 1086 Network management MAY be supported by IPv6 nodes. However, for IPv6 1087 nodes that are embedded devices, network management may be the only 1088 possible way of controlling these nodes. 1090 Existing network management protocols include SNMP [RFC3411], NETCONF 1091 [RFC6241] and RESTCONF [RFC8040]. 1093 16.1. Management Information Base (MIB) Modules 1095 [RFC8096] clarifies the obsoleted status of various IPv6-specific MIB 1096 modules. 1098 The following two MIB modules SHOULD be supported by nodes that 1099 support a Simple Network Management Protocol (SNMP) agent. 1101 16.1.1. IP Forwarding Table MIB 1103 The IP Forwarding Table MIB [RFC4292] SHOULD be supported by nodes 1104 that support an SNMP agent. 1106 16.1.2. Management Information Base for the Internet Protocol (IP) 1108 The IP MIB [RFC4293] SHOULD be supported by nodes that support an 1109 SNMP agent. 1111 16.1.3. Interface MIB 1113 The Interface MIB [RFC2863] SHOULD be supported by nodes the support 1114 an SNMP agent. 1116 16.2. YANG Data Models 1118 The following YANG data models SHOULD be supported by nodes that 1119 support a NETCONF or RESTCONF agent. 1121 16.2.1. IP Management YANG Model 1123 The IP Management YANG Model [I-D.ietf-netmod-rfc7277bis] SHOULD be 1124 supported by nodes that support NETCONF or RESTCONF. 1126 16.2.2. Interface Management YANG Model 1128 The Interface Management YANG Model [I-D.ietf-netmod-rfc7223bis] 1129 SHOULD be supported by nodes that support NETCONF or RESTCONF. 1131 17. Security Considerations 1133 This document does not directly affect the security of the Internet, 1134 beyond the security considerations associated with the individual 1135 protocols. 1137 Security is also discussed in Section 13 above. 1139 18. IANA Considerations 1141 This document does not require any IANA actions. 1143 19. Authors and Acknowledgments 1145 19.1. Authors and Acknowledgments (Current Document) 1147 For this version of the IPv6 Node Requirements document, the authors 1148 would like to thank Brian Carpenter, Dave Thaler, Tom Herbert, Erik 1149 Kline, Mohamed Boucadair, and Michayla Newcombe for their 1150 contributions. 1152 19.2. Authors and Acknowledgments from RFC 6434 1154 Ed Jankiewicz and Thomas Narten were named authors of the previous 1155 iteration of this document, RFC6434. 1157 For this version of the document, the authors thanked Hitoshi Asaeda, 1158 Brian Carpenter, Tim Chown, Ralph Droms, Sheila Frankel, Sam Hartman, 1159 Bob Hinden, Paul Hoffman, Pekka Savola, Yaron Sheffer, and Dave 1160 Thaler. 1162 19.3. Authors and Acknowledgments from RFC 4294 1164 The original version of this document (RFC 4294) was written by the 1165 IPv6 Node Requirements design team, which had the following members: 1166 Jari Arkko, Marc Blanchet, Samita Chakrabarti, Alain Durand, Gerard 1167 Gastaud, Jun-ichiro Itojun Hagino, Atsushi Inoue, Masahiro Ishiyama, 1168 John Loughney, Rajiv Raghunarayan, Shoichi Sakane, Dave Thaler, and 1169 Juha Wiljakka. 1171 The authors would like to thank Ran Atkinson, Jim Bound, Brian 1172 Carpenter, Ralph Droms, Christian Huitema, Adam Machalek, Thomas 1173 Narten, Juha Ollila, and Pekka Savola for their comments. Thanks to 1174 Mark Andrews for comments and corrections on DNS text. Thanks to 1175 Alfred Hoenes for tracking the updates to various RFCs. 1177 20. Appendix: Changes from RFC 6434 1179 There have been many editorial clarifications as well as significant 1180 additions and updates. While this section highlights some of the 1181 changes, readers should not rely on this section for a comprehensive 1182 list of all changes. 1184 1. Restructured sections 1186 2. Added 6LoWPAN to link layers as it has some deployment. 1188 3. Removed DOD IPv6 Profile as it hasn't been updated. 1190 4. Updated to MLDv2 support to a MUST since nodes are restricted if 1191 MLDv1 is used. 1193 5. Require DNS RA Options so SLAAC-only devices can get DNS, 1194 RFC8106 is a MUST. 1196 6. Require RFC3646 DNS Options for DHCPv6 implementations. 1198 7. Added RESTCONF and NETCONF as possible options to Network 1199 management. 1201 8. Added section on constrained devices. 1203 9. Added text on RFC7934, address availability to hosts (SHOULD). 1205 10. Added text on RFC7844, anonymity profiles for DHCPv6 clients. 1207 11. mDNS and DNS-SD added as updated service discovery. 1209 12. Added RFC8028 as a SHOULD as a method for solving multi-prefix 1210 network 1212 13. Added ECN RFC3168 as a SHOULD, since recent reports have shown 1213 this as useful, and added a note on RFC8311, which is related. 1215 14. Added reference to RFC7123 for Security over IPv4-only networks 1217 15. Removed Jumbograms RFC2675 as they aren't deployed. 1219 16. Updated Obseleted RFCs to the new version of the RFC including 1220 2460, 1981, 7321, 4307 1222 17. Added RFC7772 for power comsumptions considerations 1224 18. Added why /64 boundries for more detail - RFC 7421 1226 19. Added a Unique IPv6 Prefix per Host to support currently 1227 deployed IPv6 networks 1229 20. Clarified RFC7066 was snapshot for 3GPP 1231 21. Updated 4191 as a MUST, SHOULD for Type C Host as it helps solve 1232 multi-prefix problem 1234 22. Removed IPv6 over ATM since there aren't many deployments 1236 23. Added a note in Section 6.6 for RFC6724 Section 5.5/ 1237 24. Added MUST for BCP 198 for forwarding IPv6 packets 1239 25. Added reference to RFC8064 for stable address creation. 1241 26. Added text on protection from excessive EH options 1243 27. Added text on dangers of 1280 MTU UDP, esp. wrt DNS traffic 1245 28. Added text to clarify RFC8200 behaviour for unrecognized EHs or 1246 unrecognized ULPs 1248 29. Removed dated email addresses from design team acknowledgements 1249 for RFC 4294. 1251 21. Appendix: Changes from RFC 4294 1253 There have been many editorial clarifications as well as significant 1254 additions and updates. While this section highlights some of the 1255 changes, readers should not rely on this section for a comprehensive 1256 list of all changes. 1258 1. Updated the Introduction to indicate that this document is an 1259 applicability statement and is aimed at general nodes. 1261 2. Significantly updated the section on Mobility protocols, adding 1262 references and downgrading previous SHOULDs to MAYs. 1264 3. Changed Sub-IP Layer section to just list relevant RFCs, and 1265 added some more RFCs. 1267 4. Added section on SEND (it is a MAY). 1269 5. Revised section on Privacy Extensions [RFC4941] to add more 1270 nuance to recommendation. 1272 6. Completely revised IPsec/IKEv2 section, downgrading overall 1273 recommendation to a SHOULD. 1275 7. Upgraded recommendation of DHCPv6 to SHOULD. 1277 8. Added background section on DHCP versus RA options, added SHOULD 1278 recommendation for DNS configuration via RAs (RFC6106), and 1279 cleaned up DHCP recommendations. 1281 9. Added recommendation that routers implement Sections 7.3 and 7.5 1282 of [RFC6275]. 1284 10. Added pointer to subnet clarification document [RFC5942]. 1286 11. Added text that "IPv6 Host-to-Router Load Sharing" [RFC4311] 1287 SHOULD be implemented. 1289 12. Added reference to [RFC5722] (Overlapping Fragments), and made 1290 it a MUST to implement. 1292 13. Made "A Recommendation for IPv6 Address Text Representation" 1293 [RFC5952] a SHOULD. 1295 14. Removed mention of "DNAME" from the discussion about [RFC3363]. 1297 15. Numerous updates to reflect newer versions of IPv6 documents, 1298 including [RFC4443], [RFC4291], [RFC3596], and [RFC4213]. 1300 16. Removed discussion of "Managed" and "Other" flags in RAs. There 1301 is no consensus at present on how to process these flags, and 1302 discussion of their semantics was removed in the most recent 1303 update of Stateless Address Autoconfiguration [RFC4862]. 1305 17. Added many more references to optional IPv6 documents. 1307 18. Made "A Recommendation for IPv6 Address Text Representation" 1308 [RFC5952] a SHOULD. 1310 19. Added reference to [RFC5722] (Overlapping Fragments), and made 1311 it a MUST to implement. 1313 20. Updated MLD section to include reference to Lightweight MLD 1314 [RFC5790]. 1316 21. Added SHOULD recommendation for "Default Router Preferences and 1317 More-Specific Routes" [RFC4191]. 1319 22. Made "IPv6 Flow Label Specification" [RFC6437] a SHOULD. 1321 22. References 1323 22.1. Normative References 1325 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1326 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1327 . 1329 [RFC1035] Mockapetris, P., "Domain names - implementation and 1330 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1331 November 1987, . 1333 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1334 Requirement Levels", BCP 14, RFC 2119, 1335 DOI 10.17487/RFC2119, March 1997, 1336 . 1338 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1339 Listener Discovery (MLD) for IPv6", RFC 2710, 1340 DOI 10.17487/RFC2710, October 1999, 1341 . 1343 [RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", 1344 RFC 2711, DOI 10.17487/RFC2711, October 1999, 1345 . 1347 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 1348 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 1349 . 1351 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 1352 of Explicit Congestion Notification (ECN) to IP", 1353 RFC 3168, DOI 10.17487/RFC3168, September 2001, 1354 . 1356 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1357 C., and M. Carney, "Dynamic Host Configuration Protocol 1358 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1359 2003, . 1361 [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An 1362 Architecture for Describing Simple Network Management 1363 Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, 1364 DOI 10.17487/RFC3411, December 2002, 1365 . 1367 [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 1368 "DNS Extensions to Support IP Version 6", STD 88, 1369 RFC 3596, DOI 10.17487/RFC3596, October 2003, 1370 . 1372 [RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol 1373 (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736, 1374 April 2004, . 1376 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1377 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1378 DOI 10.17487/RFC3810, June 2004, 1379 . 1381 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1382 Rose, "DNS Security Introduction and Requirements", 1383 RFC 4033, DOI 10.17487/RFC4033, March 2005, 1384 . 1386 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1387 Rose, "Resource Records for the DNS Security Extensions", 1388 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1389 . 1391 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1392 Rose, "Protocol Modifications for the DNS Security 1393 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, 1394 . 1396 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1397 for IPv6 Hosts and Routers", RFC 4213, 1398 DOI 10.17487/RFC4213, October 2005, 1399 . 1401 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1402 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1403 2006, . 1405 [RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, 1406 DOI 10.17487/RFC4292, April 2006, 1407 . 1409 [RFC4293] Routhier, S., Ed., "Management Information Base for the 1410 Internet Protocol (IP)", RFC 4293, DOI 10.17487/RFC4293, 1411 April 2006, . 1413 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1414 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 1415 December 2005, . 1417 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1418 RFC 4303, DOI 10.17487/RFC4303, December 2005, 1419 . 1421 [RFC4311] Hinden, R. and D. Thaler, "IPv6 Host-to-Router Load 1422 Sharing", RFC 4311, DOI 10.17487/RFC4311, November 2005, 1423 . 1425 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1426 Control Message Protocol (ICMPv6) for the Internet 1427 Protocol Version 6 (IPv6) Specification", STD 89, 1428 RFC 4443, DOI 10.17487/RFC4443, March 2006, 1429 . 1431 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 1432 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 1433 . 1435 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 1436 (CIDR): The Internet Address Assignment and Aggregation 1437 Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August 1438 2006, . 1440 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1441 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1442 DOI 10.17487/RFC4861, September 2007, 1443 . 1445 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1446 Address Autoconfiguration", RFC 4862, 1447 DOI 10.17487/RFC4862, September 2007, 1448 . 1450 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1451 Extensions for Stateless Address Autoconfiguration in 1452 IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, 1453 . 1455 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 1456 of Type 0 Routing Headers in IPv6", RFC 5095, 1457 DOI 10.17487/RFC5095, December 2007, 1458 . 1460 [RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers", 1461 RFC 5453, DOI 10.17487/RFC5453, February 2009, 1462 . 1464 [RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", 1465 RFC 5722, DOI 10.17487/RFC5722, December 2009, 1466 . 1468 [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 1469 Group Management Protocol Version 3 (IGMPv3) and Multicast 1470 Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, 1471 DOI 10.17487/RFC5790, February 2010, 1472 . 1474 [RFC5942] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet 1475 Model: The Relationship between Links and Subnet 1476 Prefixes", RFC 5942, DOI 10.17487/RFC5942, July 2010, 1477 . 1479 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 1480 Address Text Representation", RFC 5952, 1481 DOI 10.17487/RFC5952, August 2010, 1482 . 1484 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 1485 and A. Bierman, Ed., "Network Configuration Protocol 1486 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 1487 . 1489 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 1490 "IPv6 Flow Label Specification", RFC 6437, 1491 DOI 10.17487/RFC6437, November 2011, 1492 . 1494 [RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and 1495 M. Bhatia, "A Uniform Format for IPv6 Extension Headers", 1496 RFC 6564, DOI 10.17487/RFC6564, April 2012, 1497 . 1499 [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, 1500 "Default Address Selection for Internet Protocol Version 6 1501 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, 1502 . 1504 [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, 1505 DOI 10.17487/RFC6762, February 2013, 1506 . 1508 [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service 1509 Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, 1510 . 1512 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1513 Bormann, "Neighbor Discovery Optimization for IPv6 over 1514 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1515 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1516 . 1518 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 1519 for DNS (EDNS(0))", STD 75, RFC 6891, 1520 DOI 10.17487/RFC6891, April 2013, 1521 . 1523 [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", 1524 RFC 6946, DOI 10.17487/RFC6946, May 2013, 1525 . 1527 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 1528 of IPv6 Extension Headers", RFC 7045, 1529 DOI 10.17487/RFC7045, December 2013, 1530 . 1532 [RFC7048] Nordmark, E. and I. Gashinsky, "Neighbor Unreachability 1533 Detection Is Too Impatient", RFC 7048, 1534 DOI 10.17487/RFC7048, January 2014, 1535 . 1537 [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of 1538 Oversized IPv6 Header Chains", RFC 7112, 1539 DOI 10.17487/RFC7112, January 2014, 1540 . 1542 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 1543 Interface Identifiers with IPv6 Stateless Address 1544 Autoconfiguration (SLAAC)", RFC 7217, 1545 DOI 10.17487/RFC7217, April 2014, 1546 . 1548 [I-D.ietf-netmod-rfc7223bis] 1549 Bjorklund, M., "A YANG Data Model for Interface 1550 Management", draft-ietf-netmod-rfc7223bis-03 (work in 1551 progress), January 2018. 1553 [I-D.ietf-netmod-rfc7277bis] 1554 Bjorklund, M., "A YANG Data Model for IP Management", 1555 draft-ietf-netmod-rfc7277bis-03 (work in progress), 1556 January 2018. 1558 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1559 Kivinen, "Internet Key Exchange Protocol Version 2 1560 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 1561 2014, . 1563 [RFC7527] Asati, R., Singh, H., Beebee, W., Pignataro, C., Dart, E., 1564 and W. George, "Enhanced Duplicate Address Detection", 1565 RFC 7527, DOI 10.17487/RFC7527, April 2015, 1566 . 1568 [RFC7559] Krishnan, S., Anipko, D., and D. Thaler, "Packet-Loss 1569 Resiliency for Router Solicitations", RFC 7559, 1570 DOI 10.17487/RFC7559, May 2015, 1571 . 1573 [RFC7608] Boucadair, M., Petrescu, A., and F. Baker, "IPv6 Prefix 1574 Length Recommendation for Forwarding", BCP 198, RFC 7608, 1575 DOI 10.17487/RFC7608, July 2015, 1576 . 1578 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 1579 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 1580 February 2016, . 1582 [RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6 1583 Atomic Fragments Considered Harmful", RFC 8021, 1584 DOI 10.17487/RFC8021, January 2017, 1585 . 1587 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 1588 Hosts in a Multi-Prefix Network", RFC 8028, 1589 DOI 10.17487/RFC8028, November 2016, 1590 . 1592 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 1593 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 1594 . 1596 [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, 1597 "Recommendation on Stable IPv6 Interface Identifiers", 1598 RFC 8064, DOI 10.17487/RFC8064, February 2017, 1599 . 1601 [RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 1602 "IPv6 Router Advertisement Options for DNS Configuration", 1603 RFC 8106, DOI 10.17487/RFC8106, March 2017, 1604 . 1606 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1607 (IPv6) Specification", STD 86, RFC 8200, 1608 DOI 10.17487/RFC8200, July 2017, 1609 . 1611 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1612 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1613 DOI 10.17487/RFC8201, July 2017, 1614 . 1616 [RFC8221] Wouters, P., Migault, D., Mattsson, J., Nir, Y., and T. 1617 Kivinen, "Cryptographic Algorithm Implementation 1618 Requirements and Usage Guidance for Encapsulating Security 1619 Payload (ESP) and Authentication Header (AH)", RFC 8221, 1620 DOI 10.17487/RFC8221, October 2017, 1621 . 1623 [RFC8247] Nir, Y., Kivinen, T., Wouters, P., and D. Migault, 1624 "Algorithm Implementation Requirements and Usage Guidance 1625 for the Internet Key Exchange Protocol Version 2 (IKEv2)", 1626 RFC 8247, DOI 10.17487/RFC8247, September 2017, 1627 . 1629 [RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion 1630 Notification (ECN) Experimentation", RFC 8311, 1631 DOI 10.17487/RFC8311, January 2018, 1632 . 1634 22.2. Informative References 1636 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 1637 RFC 793, DOI 10.17487/RFC0793, September 1981, 1638 . 1640 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 1641 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 1642 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 1643 September 1997, . 1645 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1646 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1647 . 1649 [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 1650 over Non-Broadcast Multiple Access (NBMA) networks", 1651 RFC 2491, DOI 10.17487/RFC2491, January 1999, 1652 . 1654 [RFC2590] Conta, A., Malis, A., and M. Mueller, "Transmission of 1655 IPv6 Packets over Frame Relay Networks Specification", 1656 RFC 2590, DOI 10.17487/RFC2590, May 1999, 1657 . 1659 [RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", 1660 RFC 2923, DOI 10.17487/RFC2923, September 2000, 1661 . 1663 [RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets 1664 over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146, 1665 October 2001, . 1667 [RFC3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. 1668 Hain, "Representing Internet Protocol version 6 (IPv6) 1669 Addresses in the Domain Name System (DNS)", RFC 3363, 1670 DOI 10.17487/RFC3363, August 2002, 1671 . 1673 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 1674 Stevens, "Basic Socket Interface Extensions for IPv6", 1675 RFC 3493, DOI 10.17487/RFC3493, February 2003, 1676 . 1678 [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, 1679 "Advanced Sockets Application Program Interface (API) for 1680 IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003, 1681 . 1683 [RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic 1684 Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, 1685 DOI 10.17487/RFC3646, December 2003, 1686 . 1688 [RFC3678] Thaler, D., Fenner, B., and B. Quinn, "Socket Interface 1689 Extensions for Multicast Source Filters", RFC 3678, 1690 DOI 10.17487/RFC3678, January 2004, 1691 . 1693 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1694 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1695 2011, . 1697 [RFC3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to 1698 Protect Mobile IPv6 Signaling Between Mobile Nodes and 1699 Home Agents", RFC 3776, DOI 10.17487/RFC3776, June 2004, 1700 . 1702 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 1703 "SEcure Neighbor Discovery (SEND)", RFC 3971, 1704 DOI 10.17487/RFC3971, March 2005, 1705 . 1707 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 1708 RFC 3972, DOI 10.17487/RFC3972, March 2005, 1709 . 1711 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 1712 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 1713 November 2005, . 1715 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 1716 DOI 10.17487/RFC4302, December 2005, 1717 . 1719 [RFC4338] DeSanti, C., Carlson, C., and R. Nixon, "Transmission of 1720 IPv6, IPv4, and Address Resolution Protocol (ARP) Packets 1721 over Fibre Channel", RFC 4338, DOI 10.17487/RFC4338, 1722 January 2006, . 1724 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 1725 Network Address Translations (NATs)", RFC 4380, 1726 DOI 10.17487/RFC4380, February 2006, 1727 . 1729 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1730 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1731 . 1733 [RFC4584] Chakrabarti, S. and E. Nordmark, "Extension to Sockets API 1734 for Mobile IPv6", RFC 4584, DOI 10.17487/RFC4584, July 1735 2006, . 1737 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 1738 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 1739 . 1741 [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 1742 IKEv2 and the Revised IPsec Architecture", RFC 4877, 1743 DOI 10.17487/RFC4877, April 2007, 1744 . 1746 [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, 1747 "Extended ICMP to Support Multi-Part Messages", RFC 4884, 1748 DOI 10.17487/RFC4884, April 2007, 1749 . 1751 [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering 1752 ICMPv6 Messages in Firewalls", RFC 4890, 1753 DOI 10.17487/RFC4890, May 2007, 1754 . 1756 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 1757 over Low-Power Wireless Personal Area Networks (6LoWPANs): 1758 Overview, Assumptions, Problem Statement, and Goals", 1759 RFC 4919, DOI 10.17487/RFC4919, August 2007, 1760 . 1762 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 1763 "Transmission of IPv6 Packets over IEEE 802.15.4 1764 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 1765 . 1767 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 1768 Socket API for Source Address Selection", RFC 5014, 1769 DOI 10.17487/RFC5014, September 2007, 1770 . 1772 [RFC5072] Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6 1773 over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007, 1774 . 1776 [RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S. 1777 Madanapalli, "Transmission of IPv6 via the IPv6 1778 Convergence Sublayer over IEEE 802.16 Networks", RFC 5121, 1779 DOI 10.17487/RFC5121, February 2008, 1780 . 1782 [RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack 1783 Hosts and Routers", RFC 5555, DOI 10.17487/RFC5555, June 1784 2009, . 1786 [RFC6563] Jiang, S., Conrad, D., and B. Carpenter, "Moving A6 to 1787 Historic Status", RFC 6563, DOI 10.17487/RFC6563, March 1788 2012, . 1790 [RFC7066] Korhonen, J., Ed., Arkko, J., Ed., Savolainen, T., and S. 1791 Krishnan, "IPv6 for Third Generation Partnership Project 1792 (3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066, 1793 November 2013, . 1795 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1796 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1797 DOI 10.17487/RFC7084, November 2013, 1798 . 1800 [RFC7123] Gont, F. and W. Liu, "Security Implications of IPv6 on 1801 IPv4 Networks", RFC 7123, DOI 10.17487/RFC7123, February 1802 2014, . 1804 [RFC7278] Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6 1805 /64 Prefix from a Third Generation Partnership Project 1806 (3GPP) Mobile Interface to a LAN Link", RFC 7278, 1807 DOI 10.17487/RFC7278, June 2014, 1808 . 1810 [RFC7371] Boucadair, M. and S. Venaas, "Updates to the IPv6 1811 Multicast Addressing Architecture", RFC 7371, 1812 DOI 10.17487/RFC7371, September 2014, 1813 . 1815 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1816 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1817 Boundary in IPv6 Addressing", RFC 7421, 1818 DOI 10.17487/RFC7421, January 2015, 1819 . 1821 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 1822 Considerations for IPv6 Address Generation Mechanisms", 1823 RFC 7721, DOI 10.17487/RFC7721, March 2016, 1824 . 1826 [RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy 1827 Consumption of Router Advertisements", BCP 202, RFC 7772, 1828 DOI 10.17487/RFC7772, February 2016, 1829 . 1831 [RFC7844] Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity 1832 Profiles for DHCP Clients", RFC 7844, 1833 DOI 10.17487/RFC7844, May 2016, 1834 . 1836 [RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi, 1837 "Host Address Availability Recommendations", BCP 204, 1838 RFC 7934, DOI 10.17487/RFC7934, July 2016, 1839 . 1841 [RFC8096] Fenner, B., "The IPv6-Specific MIB Modules Are Obsolete", 1842 RFC 8096, DOI 10.17487/RFC8096, April 2017, 1843 . 1845 [RFC8273] Brzozowski, J. and G. Van de Velde, "Unique IPv6 Prefix 1846 per Host", RFC 8273, DOI 10.17487/RFC8273, December 2017, 1847 . 1849 [POSIX] IEEE, "IEEE Std. 1003.1-2008 Standard for Information 1850 Technology -- Portable Operating System Interface (POSIX), 1851 ISO/IEC 9945:2009", . 1853 [USGv6] National Institute of Standards and Technology, "A Profile 1854 for IPv6 in the U.S. Government - Version 1.0", July 2008, 1855 . 1857 Authors' Addresses 1859 Tim Chown 1860 Jisc 1861 Lumen House, Library Avenue 1862 Harwell Oxford, Didcot OX11 0SG 1863 United Kingdom 1865 Email: tim.chown@jisc.ac.uk 1867 John Loughney 1868 Intel 1869 Santa Clara, CA 1870 USA 1872 Email: john.loughney@gmail.com 1874 Timothy Winters 1875 University of New Hampshire, Interoperability Lab (UNH-IOL) 1876 Durham, NH 1877 United States 1879 Email: twinters@iol.unh.edu