idnits 2.17.1 draft-ietf-6man-rfc6434-bis-09.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: IPv6 nodes MUST not create overlapping fragments. Also, when reassembling an IPv6 datagram, if one or more of its constituent fragments is determined to be an overlapping fragment, the entire datagram (and any constituent fragments) MUST be silently discarded. See [RFC5722] for more information. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: As described in RFC 8201, nodes implementing Path MTU Discovery and sending packets larger than the IPv6 minimum link MTU are susceptible to problematic connectivity if ICMPv6 messages are blocked or not transmitted. For example, this will result in connections that complete the TCP three-way handshake correctly but then hang when data is transferred. This state is referred to as a black-hole connection [RFC2923]. Path MTU Discovery relies on ICMPv6 Packet Too Big (PTB) to determine the MTU of the path (and thus these MUST not be filtered, as per the recommendation in [RFC4890]). -- The document date (July 16, 2018) is 2111 days in the past. Is this intentional? 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 8021 -- Obsolete informational reference (is this intentional?): RFC 793 (Obsoleted by RFC 9293) Summary: 4 errors (**), 0 flaws (~~), 3 warnings (==), 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: January 17, 2019 T. Winters 7 UNH-IOL 8 July 16, 2018 10 IPv6 Node Requirements 11 draft-ietf-6man-rfc6434-bis-09 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 January 17, 2019. 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 . . . . . . . . . . . . . . . . 4 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 . . . . . . . . . . . . . . . . 21 109 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. IPv6 Node 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 . . . . . . . . . . . . . . . . . 24 127 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, NIST has defined profiles for specialized requirements for 171 IPv6 in target environments (see [USGv6]). 173 As it is not always possible for an implementer to know the exact 174 usage of IPv6 in a node, an overriding requirement for IPv6 nodes is 175 that they should adhere to Jon Postel's Robustness Principle: "Be 176 conservative in what you do, be liberal in what you accept from 177 others" [RFC0793]. 179 1.1. Scope of This Document 181 IPv6 covers many specifications. It is intended that IPv6 will be 182 deployed in many different situations and environments. Therefore, 183 it is important to develop requirements for IPv6 nodes to ensure 184 interoperability. 186 1.2. Description of IPv6 Nodes 188 From the Internet Protocol, Version 6 (IPv6) Specification [RFC8200], 189 we have the following definitions: 191 IPv6 node - a device that implements IPv6. 192 IPv6 router - a node that forwards IPv6 packets not explicitly 193 addressed to itself. 194 IPv6 host - any IPv6 node that is not a router. 196 2. Requirements Language 198 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 199 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 200 document are to be interpreted as described in RFC 2119 [RFC2119] 201 8174 [RFC8174] when, and only when, they appear in all capitals, as 202 show here. 204 3. Abbreviations Used in This Document 206 AH Authentication Header 207 DAD Duplicate Address Detection 208 ESP Encapsulating Security Payload 209 ICMP Internet Control Message Protocol 210 IKE Internet Key Exchange 211 MIB Management Information Base 212 MLD Multicast Listener Discovery 213 MTU Maximum Transmission Unit 214 NA Neighbor Advertisement 215 NBMA Non-Broadcast Multiple Access 216 ND Neighbor Discovery 217 NS Neighbor Solicitation 218 NUD Neighbor Unreachability Detection 219 PPP Point-to-Point Protocol 221 4. Sub-IP Layer 223 An IPv6 node MUST include support for one or more IPv6 link-layer 224 specifications. Which link-layer specifications an implementation 225 should include will depend upon what link-layers are supported by the 226 hardware available on the system. It is possible for a conformant 227 IPv6 node to support IPv6 on some of its interfaces and not on 228 others. 230 As IPv6 is run over new layer 2 technologies, it is expected that new 231 specifications will be issued. In the following, we list some of the 232 layer 2 technologies for which an IPv6 specification has been 233 developed. It is provided for informational purposes only and may 234 not be complete. 236 - Transmission of IPv6 Packets over Ethernet Networks [RFC2464] 237 - Transmission of IPv6 Packets over Frame Relay Networks 238 Specification [RFC2590] 240 - Transmission of IPv6 Packets over IEEE 1394 Networks [RFC3146] 242 - Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) 243 Packets over Fibre Channel [RFC4338] 245 - Transmission of IPv6 Packets over IEEE 802.15.4 Networks [RFC4944] 247 - Transmission of IPv6 via the IPv6 Convergence Sublayer over IEEE 248 802.16 Networks [RFC5121] 250 - IP version 6 over PPP [RFC5072] 252 In addition to traditional physical link-layers, it is also possible 253 to tunnel IPv6 over other protocols. Examples include: 255 - Teredo: Tunneling IPv6 over UDP through Network Address 256 Translations (NATs) [RFC4380] 258 - Section 3 of "Basic Transition Mechanisms for IPv6 Hosts and 259 Routers" [RFC4213] 261 5. IP Layer 263 5.1. Internet Protocol Version 6 - RFC 8200 265 The Internet Protocol Version 6 is specified in [RFC8200]. This 266 specification MUST be supported. 268 The node MUST follow the packet transmission rules in RFC 8200. 270 All conformant IPv6 implementations MUST be capable of sending and 271 receiving IPv6 packets; forwarding functionality MAY be supported. 272 Nodes MUST always be able to send, receive, and process fragment 273 headers. 275 IPv6 nodes MUST not create overlapping fragments. Also, when 276 reassembling an IPv6 datagram, if one or more of its constituent 277 fragments is determined to be an overlapping fragment, the entire 278 datagram (and any constituent fragments) MUST be silently discarded. 279 See [RFC5722] for more information. 281 As recommended in [RFC8021], nodes MUST NOT generate atomic 282 fragments, i.e., where the fragment is a whole datagram. As per 283 [RFC6946], if a receiving node reassembling a datagram encounters an 284 atomic fragment, it should be processed as a fully reassembled 285 packet, and any other fragments that match this packet should be 286 processed independently. 288 To mitigate a variety of potential attacks, nodes SHOULD avoid using 289 predictable fragment Identification values in Fragment Headers, as 290 discussed in [RFC7739]. 292 All nodes SHOULD support the setting and use of the IPv6 Flow Label 293 field as defined in the IPv6 Flow Label specification [RFC6437]. 294 Forwarding nodes such as routers and load distributors MUST NOT 295 depend only on Flow Label values being uniformly distributed. It is 296 RECOMMENDED that source hosts support the flow label by setting the 297 Flow Label field for all packets of a given flow to the same value 298 chosen from an approximation to a discrete uniform distribution. 300 5.2. Support for IPv6 Extension Headers 302 RFC 8200 specifies extension headers and the processing for these 303 headers. 305 Extension headers (except for the Hop-by-Hop Options header) are not 306 processed, inserted, or deleted by any node along a packet's delivery 307 path, until the packet reaches the node (or each of the set of nodes, 308 in the case of multicast) identified in the Destination Address field 309 of the IPv6 header. 311 Any unrecognized extension headers or options MUST be processed as 312 described in RFC 8200. Note that where Section 4 of RFC 8200 refers 313 to the action to be taken when a Next Header value in the current 314 header is not recognized by a node, that action applies whether the 315 value is an unrecognized Extension Header or an unrecognized upper 316 layer protocol (ULP). 318 An IPv6 node MUST be able to process these extension headers. An 319 exception is Routing Header type 0 (RH0), which was deprecated by 320 [RFC5095] due to security concerns and which MUST be treated as an 321 unrecognized routing type. 323 Further, [RFC7045] adds specific requirements for processing of 324 Extension Headers, in particular that any forwarding node along an 325 IPv6 packet's path, which forwards the packet for any reason, SHOULD 326 do so regardless of any extension headers that are present. 328 As per RFC 8200, when a node fragments an IPv6 datagram, it MUST 329 include the entire IPv6 Header Chain in the first fragment. The Per- 330 Fragment headers MUST consist of the IPv6 header plus any extension 331 headers that MUST be processed by nodes en route to the destination, 332 that is, all headers up to and including the Routing header if 333 present, else the Hop-by-Hop Options header if present, else no 334 extension headers. On reassembly, if the first fragment does not 335 include all headers through an Upper-Layer header, then that fragment 336 SHOULD be discarded and an ICMP Parameter Problem, Code 3, message 337 SHOULD be sent to the source of the fragment, with the Pointer field 338 set to zero. See [RFC7112] for a discussion of why oversized IPv6 339 Extension Header chains are avoided. 341 Defining new IPv6 extension headers is not recommended, unless there 342 are no existing IPv6 extension headers that can be used by specifying 343 a new option for that IPv6 extension header. A proposal to specify a 344 new IPv6 extension header MUST include a detailed technical 345 explanation of why an existing IPv6 extension header can not be used 346 for the desired new function, and in such cases need to follow the 347 format described in Section 8 of RFC 8200. For further background 348 reading on this topic, see [RFC6564]. 350 5.3. Protecting a node from excessive EH options 352 As per RFC 8200, end hosts are expected to process all extension 353 headers, destination options, and hop-by-hop options in a packet. 354 Given that the only limit on the number and size of extension headers 355 is the MTU, the processing of received packets could be considerable. 356 It is also conceivable that a long chain of extension headers might 357 be used as a form of denial-of-service attack. Accordingly, a host 358 may place limits on the number and sizes of extension headers and 359 options it is willing to process. 361 A host MAY limit the number of consecutive PAD1 options in 362 destination options or hop-by-hop options to seven. In this case, if 363 the more than seven consecutive PAD1 options are present the packet 364 MAY be silently discarded. The rationale is that if padding of eight 365 or more bytes is required than the PADN option SHOULD be used. 367 A host MAY limit number of bytes in a PADN option to be less than 368 eight. In such a case, if a PADN option is present that has a length 369 greater than seven then the packet SHOULD be silently discarded. The 370 rationale for this guideline is that the purpose of padding is for 371 alignment and eight bytes is the maximum alignment used in IPv6. 373 A host MAY disallow unknown options in destination options or hop-by- 374 hop options. This SHOULD be configurable where the default is to 375 accept unknown options and process them per [RFC8200]. If a packet 376 with unknown options is received and the host is configured to 377 disallow them, then the packet SHOULD be silently discarded. 379 A host MAY impose a limit on the maximum number of non-padding 380 options allowed in the destination options and hop-by-hop extension 381 headers. If this feature is supported the maximum number SHOULD be 382 configurable and the default value SHOULD be set to eight. The 383 limits for destination options and hop-by-hop options may be 384 separately configurable. If a packet is received and the number of 385 destination or hop-by-hop options exceeds the limit, then the packet 386 SHOULD be silently discarded. 388 A host MAY impose a limit on the maximum length of destination 389 options or hop-by-hop options extension header. This value SHOULD be 390 configurable and the default is to accept options of any length. If 391 a packet is received and the length of destination or hop-by-hop 392 options extension header exceeds the length limit, then the packet 393 SHOULD be silently discarded. 395 5.4. Neighbor Discovery for IPv6 - RFC 4861 397 Neighbor Discovery is defined in [RFC4861]; the definition was 398 updated by [RFC5942]. Neighbor Discovery SHOULD be supported. RFC 399 4861 states: 401 Unless specified otherwise (in a document that covers operating IP 402 over a particular link type) this document applies to all link 403 types. However, because ND uses link-layer multicast for some of 404 its services, it is possible that on some link types (e.g., Non- 405 Broadcast Multi-Access (NBMA) links), alternative protocols or 406 mechanisms to implement those services will be specified (in the 407 appropriate document covering the operation of IP over a 408 particular link type). The services described in this document 409 that are not directly dependent on multicast, such as Redirects, 410 next-hop determination, Neighbor Unreachability Detection, etc., 411 are expected to be provided as specified in this document. The 412 details of how one uses ND on NBMA links are addressed in 413 [RFC2491]. 415 Some detailed analysis of Neighbor Discovery follows: 417 Router Discovery is how hosts locate routers that reside on an 418 attached link. Hosts MUST support Router Discovery functionality. 420 Prefix Discovery is how hosts discover the set of address prefixes 421 that define which destinations are on-link for an attached link. 422 Hosts MUST support Prefix Discovery. 424 Hosts MUST also implement Neighbor Unreachability Detection (NUD) for 425 all paths between hosts and neighboring nodes. NUD is not required 426 for paths between routers. However, all nodes MUST respond to 427 unicast Neighbor Solicitation (NS) messages. 429 [RFC7048] discusses NUD, in particular cases where it behaves too 430 impatiently. It states that if a node transmits more than a certain 431 number of packets, then it SHOULD use the exponential backoff of the 432 retransmit timer, up to a certain threshold point. 434 Hosts MUST support the sending of Router Solicitations and the 435 receiving of Router Advertisements. The ability to understand 436 individual Router Advertisement options is dependent on supporting 437 the functionality making use of the particular option. 439 [RFC7559] discusses packet loss resiliency for Router Solicitations, 440 and requires that nodes MUST use a specific exponential backoff 441 algorithm for RS retransmissions. 443 All nodes MUST support the sending and receiving of Neighbor 444 Solicitation (NS) and Neighbor Advertisement (NA) messages. NS and 445 NA messages are required for Duplicate Address Detection (DAD). 447 Hosts SHOULD support the processing of Redirect functionality. 448 Routers MUST support the sending of Redirects, though not necessarily 449 for every individual packet (e.g., due to rate limiting). Redirects 450 are only useful on networks supporting hosts. In core networks 451 dominated by routers, Redirects are typically disabled. The sending 452 of Redirects SHOULD be disabled by default on routers intended to 453 deployed on core networks. They MAY be enabled by default on routers 454 intended to support hosts on edge networks. 456 "IPv6 Host-to-Router Load Sharing" [RFC4311] includes additional 457 recommendations on how to select from a set of available routers. 458 [RFC4311] SHOULD be supported. 460 5.5. SEcure Neighbor Discovery (SEND) - RFC 3971 462 SEND [RFC3971] and Cryptographically Generated Addresses (CGAs) 463 [RFC3972] provide a way to secure the message exchanges of Neighbor 464 Discovery. SEND has the potential to address certain classes of 465 spoofing attacks, but it does not provide specific protection for 466 threats from off-link attackers. 468 There have been relatively few implementations of SEND in common 469 operating systems and platforms since its publication in 2005, and 470 thus deployment experience remains very limited to date. 472 At this time, support for SEND is considered optional. Due to the 473 complexity in deploying SEND, and its heavyweight provisioning, its 474 deployment is only likely to be considered where nodes are operating 475 in a particularly strict security environment. 477 5.6. IPv6 Router Advertisement Flags Option - RFC 5175 479 Router Advertisements include an 8-bit field of single-bit Router 480 Advertisement flags. The Router Advertisement Flags Option extends 481 the number of available flag bits by 48 bits. At the time of this 482 writing, 6 of the original 8 single-bit flags have been assigned, 483 while 2 remain available for future assignment. No flags have been 484 defined that make use of the new option, and thus, strictly speaking, 485 there is no requirement to implement the option today. However, 486 implementations that are able to pass unrecognized options to a 487 higher-level entity that may be able to understand them (e.g., a 488 user-level process using a "raw socket" facility) MAY take steps to 489 handle the option in anticipation of a future usage. 491 5.7. Path MTU Discovery and Packet Size 493 5.7.1. Path MTU Discovery - RFC 8201 495 "Path MTU Discovery for IP version 6" [RFC8201] SHOULD be supported. 496 From [RFC8200]: 498 It is strongly recommended that IPv6 nodes implement Path MTU 499 Discovery [RFC8201], in order to discover and take advantage of 500 path MTUs greater than 1280 octets. However, a minimal IPv6 501 implementation (e.g., in a boot ROM) may simply restrict itself to 502 sending packets no larger than 1280 octets, and omit 503 implementation of Path MTU Discovery. 505 The rules in [RFC8200] and [RFC5722] MUST be followed for packet 506 fragmentation and reassembly. 508 As described in RFC 8201, nodes implementing Path MTU Discovery and 509 sending packets larger than the IPv6 minimum link MTU are susceptible 510 to problematic connectivity if ICMPv6 messages are blocked or not 511 transmitted. For example, this will result in connections that 512 complete the TCP three-way handshake correctly but then hang when 513 data is transferred. This state is referred to as a black-hole 514 connection [RFC2923]. Path MTU Discovery relies on ICMPv6 Packet Too 515 Big (PTB) to determine the MTU of the path (and thus these MUST not 516 be filtered, as per the recommendation in [RFC4890]). 518 An alternative to Path MTU Discovery defined in RFC 8201 can be found 519 in [RFC4821], which defines a method for Packetization Layer Path MTU 520 Discovery (PLPMTUD) designed for use over paths where delivery of 521 ICMPv6 messages to a host is not assured. 523 5.7.2. Minimum MTU considerations 525 While an IPv6 link MTU can be set to 1280 bytes, it is recommended 526 that for IPv6 UDP in particular, which includes DNS operation, the 527 sender use a large MTU if they can, in order to avoid gratuitous 528 fragmentation-caused packet drops. 530 5.8. ICMP for the Internet Protocol Version 6 (IPv6) - RFC 4443 532 ICMPv6 [RFC4443] MUST be supported. "Extended ICMP to Support Multi- 533 Part Messages" [RFC4884] MAY be supported. 535 5.9. Default Router Preferences and More-Specific Routes - RFC 4191 537 "Default Router Preferences and More-Specific Routes" [RFC4191] 538 provides support for nodes attached to multiple (different) networks, 539 each providing routers that advertise themselves as default routers 540 via Router Advertisements. In some scenarios, one router may provide 541 connectivity to destinations the other router does not, and choosing 542 the "wrong" default router can result in reachability failures. In 543 order to resolve this scenario IPv6 Nodes MUST implement [RFC4191] 544 and SHOULD implement the Type C host role defined in RFC4191. 546 5.10. First-Hop Router Selection - RFC 8028 548 In multihomed scenarios, where a host has more than one prefix, each 549 allocated by an upstream network that is assumed to implement BCP 38 550 ingress filtering, the host may have multiple routers to choose from. 552 Hosts that may be deployed in such multihomed environments SHOULD 553 follow the guidance given in [RFC8028]. 555 5.11. Multicast Listener Discovery (MLD) for IPv6 - RFC 3810 557 Nodes that need to join multicast groups MUST support MLDv2 558 [RFC3810]. MLD is needed by any node that is expected to receive and 559 process multicast traffic and in particular MLDv2 is required for 560 support for source-specific multicast (SSM) as per [RFC4607]. 562 Previous versions of this document only required MLDv1 ([RFC2710]) to 563 be implemented on all nodes. Since participation of any MLDv1-only 564 nodes on a link require that all other nodeas on the link then 565 operate in version 1 compatibility mode, the requirement to support 566 MLDv2 on all nodes was upgraded to a MUST. Further, SSM is now the 567 preferred multicast distribution method, rather than ASM. 569 Note that Neighbor Discovery (as used on most link types -- see 570 Section 5.4) depends on multicast and requires that nodes join 571 Solicited Node multicast addresses. 573 5.12. Explicit Congestion Notification (ECN) - RFC 3168 575 An ECN-aware router sets a mark in the IP header in order to signal 576 impending congestion, rather than dropping a packet. The receiver of 577 the packet echoes the congestion indication to the sender, which can 578 then reduce its transmission rate as if it detected a dropped packet. 580 Nodes SHOULD support [RFC3168] by implementing an interface for the 581 upper layer to access and set the ECN bits in the IP header. The 582 benefits of using ECN are documented in [RFC8087]. 584 6. Addressing and Address Configuration 586 6.1. IP Version 6 Addressing Architecture - RFC 4291 588 The IPv6 Addressing Architecture [RFC4291] MUST be supported. 590 The current IPv6 Address Architecture is based on a 64-bit boundary 591 for subnet prefixes. The reasoning behind this decision is 592 documented in [RFC7421]. 594 Implementations MUST also support the Multicast flag updates 595 documented in [RFC7371] 597 6.2. Host Address Availability Recommendations 599 Hosts may be configured with addresses through a variety of methods, 600 including SLAAC, DHCPv6, or manual configuration. 602 [RFC7934] recommends that networks provide general-purpose end hosts 603 with multiple global IPv6 addresses when they attach, and it 604 describes the benefits of and the options for doing so. Routers 605 SHOULD support [RFC7934] for assigning multiple address to a host. 606 Host SHOULD support assigning multiple addresses as described in 607 [RFC7934]. 609 Nodes SHOULD support the capability to be assigned a prefix per host 610 as documented in [RFC8273]. Such an approach can offer improved host 611 isolation and enhanced subscriber management on shared network 612 segments. 614 6.3. IPv6 Stateless Address Autoconfiguration - RFC 4862 616 Hosts MUST support IPv6 Stateless Address Autoconfiguration. It is 617 RECOMMENDED, as described in [RFC8064], that unless there is a 618 specific requirement for MAC addresses to be embedded in an IID, 619 nodes follow the procedure in [RFC7217] to generate SLAAC-based 620 addresses, rather than using [RFC4862]. Addresses generated through 621 RFC7217 will be the same whenever a given device (re)appears on the 622 same subnet (with a specific IPv6 prefix), but the IID will vary on 623 each subnet visited. 625 Nodes that are routers MUST be able to generate link-local addresses 626 as described in [RFC4862]. 628 From RFC 4862: 630 The autoconfiguration process specified in this document applies 631 only to hosts and not routers. Since host autoconfiguration uses 632 information advertised by routers, routers will need to be 633 configured by some other means. However, it is expected that 634 routers will generate link-local addresses using the mechanism 635 described in this document. In addition, routers are expected to 636 successfully pass the Duplicate Address Detection procedure 637 described in this document on all addresses prior to assigning 638 them to an interface. 640 All nodes MUST implement Duplicate Address Detection. Quoting from 641 Section 5.4 of RFC 4862: 643 Duplicate Address Detection MUST be performed on all unicast 644 addresses prior to assigning them to an interface, regardless of 645 whether they are obtained through stateless autoconfiguration, 646 DHCPv6, or manual configuration, with the following [exceptions 647 noted therein]. 649 "Optimistic Duplicate Address Detection (DAD) for IPv6" [RFC4429] 650 specifies a mechanism to reduce delays associated with generating 651 addresses via Stateless Address Autoconfiguration [RFC4862]. RFC 652 4429 was developed in conjunction with Mobile IPv6 in order to reduce 653 the time needed to acquire and configure addresses as devices quickly 654 move from one network to another, and it is desirable to minimize 655 transition delays. For general purpose devices, RFC 4429 remains 656 optional at this time. 658 [RFC7527] discusses enhanced DAD, and describes an algorithm to 659 automate the detection of looped back IPv6 ND messages used by DAD. 660 Nodes SHOULD implement this behaviour where such detection is 661 beneficial. 663 6.4. Privacy Extensions for Address Configuration in IPv6 - RFC 4941 665 A node using Stateless Address Autoconfiguration [RFC4862] to form a 666 globally unique IPv6 address using its MAC address to generate the 667 IID will see that IID remain the same on any visited network, even 668 though the network prefix part changes. Thus it is possible for 3rd 669 party device to track the activities of the node they communicate 670 with, as that node moves around the network. Privacy Extensions for 671 Stateless Address Autoconfiguration [RFC4941] address this concern by 672 allowing nodes to configure an additional temporary address where the 673 IID is effectively randomly generated. Privacy addresses are then 674 used as source addresses for new communications initiated by the 675 node. 677 General issues regarding privacy issues for IPv6 addressing are 678 discussed in [RFC7721]. 680 RFC 4941 SHOULD be supported. In some scenarios, such as dedicated 681 servers in a data center, it provides limited or no benefit, or may 682 complicate network management. Thus devices implementing this 683 specification MUST provide a way for the end user to explicitly 684 enable or disable the use of such temporary addresses. 686 Note that RFC4941 can be used independently of traditional SLAAC, or 687 of RFC7217-based SLAAC. 689 Implementers of RFC 4941 should be aware that certain addresses are 690 reserved and should not be chosen for use as temporary addresses. 691 Consult "Reserved IPv6 Interface Identifiers" [RFC5453] for more 692 details. 694 6.5. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 696 DHCPv6 [RFC3315] can be used to obtain and configure addresses. In 697 general, a network may provide for the configuration of addresses 698 through SLAAC, DHCPv6, or both. There will be a wide range of IPv6 699 deployment models and differences in address assignment requirements, 700 some of which may require DHCPv6 for stateful address assignment. 701 Consequently, all hosts SHOULD implement address configuration via 702 DHCPv6. 704 In the absence of observed Router Advertisement messages, IPv6 nodes 705 MAY initiate DHCP to obtain IPv6 addresses and other configuration 706 information, as described in Section 5.5.2 of [RFC4862]. 708 Where devices are likely to be carried by users and attached to 709 multiple visisted networks, DHCPv6 client anonymity profiles SHOULD 710 be supported as described in [RFC7844] to minimise the disclosure of 711 identifying information. Section 5 of RFC7844 describes operational 712 considerations on the use of such anonymity profiles. 714 6.6. Default Address Selection for IPv6 - RFC 6724 716 IPv6 nodes will invariably have multiple addresses configured 717 simultaneously, and thus will need to choose which addresses to use 718 for which communications. The rules specified in the Default Address 719 Selection for IPv6 [RFC6724] document MUST be implemented. [RFC8028] 720 updates rule 5.5 from [RFC6724]; implementations SHOULD implement 721 this rule. 723 7. DNS 725 DNS is described in [RFC1034], [RFC1035], [RFC3363], and [RFC3596]. 726 Not all nodes will need to resolve names; those that will never need 727 to resolve DNS names do not need to implement resolver functionality. 728 However, the ability to resolve names is a basic infrastructure 729 capability on which applications rely, and most nodes will need to 730 provide support. All nodes SHOULD implement stub-resolver [RFC1034] 731 functionality, as in [RFC1034], Section 5.3.1, with support for: 733 - AAAA type Resource Records [RFC3596]; 735 - reverse addressing in ip6.arpa using PTR records [RFC3596]; 737 - Extension Mechanisms for DNS (EDNS0) [RFC6891] to allow for DNS 738 packet sizes larger than 512 octets. 740 Those nodes are RECOMMENDED to support DNS security extensions 741 [RFC4033] [RFC4034] [RFC4035]. 743 A6 Resource Records, which were only ever defined with Experimental 744 status in [RFC3363], are now classified as Historic, as per 745 [RFC6563]. 747 8. Configuring Non-Address Information 749 8.1. DHCP for Other Configuration Information 751 DHCP [RFC3315] Specifies a mechanism for IPv6 nodes to obtain address 752 configuration information (see Section 6.5) and to obtain additional 753 (non-address) configuration. If a host implementation supports 754 applications or other protocols that require configuration that is 755 only available via DHCP, hosts SHOULD implement DHCP. For 756 specialized devices on which no such configuration need is present, 757 DHCP may not be necessary. 759 An IPv6 node can use the subset of DHCP (described in [RFC3736]) to 760 obtain other configuration information. 762 If an IPv6 node implements DHCP it MUST implement the DNS options 763 [RFC3646] as most deployments will expect these options are 764 available. 766 8.2. Router Advertisements and Default Gateway 768 There is no defined DHCPv6 Gateway option. 770 Nodes using the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 771 are thus expected to determine their default router information and 772 on-link prefix information from received Router Advertisements. 774 8.3. IPv6 Router Advertisement Options for DNS Configuration - RFC 8106 776 Router Advertisement Options have historically been limited to those 777 that are critical to basic IPv6 functionality. Originally, DNS 778 configuration was not included as an RA option, and DHCP was the 779 recommended way to obtain DNS configuration information. Over time, 780 the thinking surrounding such an option has evolved. It is now 781 generally recognized that few nodes can function adequately without 782 having access to a working DNS resolver, and thus a Standards Track 783 document has been published to provide this capability [RFC8106]. 785 Implementations MUST include support for the DNS RA option [RFC8106]. 787 8.4. DHCP Options versus Router Advertisement Options for Host 788 Configuration 790 In IPv6, there are two main protocol mechanisms for propagating 791 configuration information to hosts: Router Advertisements (RAs) and 792 DHCP. RA options have been restricted to those deemed essential for 793 basic network functioning and for which all nodes are configured with 794 exactly the same information. Examples include the Prefix 795 Information Options, the MTU option, etc. On the other hand, DHCP 796 has generally been preferred for configuration of more general 797 parameters and for parameters that may be client-specific. Generally 798 speaking, however, there has been a desire to define only one 799 mechanism for configuring a given option, rather than defining 800 multiple (different) ways of configuring the same information. 802 One issue with having multiple ways of configuring the same 803 information is that interoperability suffers if a host chooses one 804 mechanism but the network operator chooses a different mechanism. 805 For "closed" environments, where the network operator has significant 806 influence over what devices connect to the network and thus what 807 configuration mechanisms they support, the operator may be able to 808 ensure that a particular mechanism is supported by all connected 809 hosts. In more open environments, however, where arbitrary devices 810 may connect (e.g., a WIFI hotspot), problems can arise. To maximize 811 interoperability in such environments, hosts would need to implement 812 multiple configuration mechanisms to ensure interoperability. 814 9. Service Discovery Protocols 816 [RFC6762] and [RFC6763] describe multicast DNS (mDNS) and DNS-Based 817 Service Discovery (DNS-SD) respectively. These protocols, 818 collectively commonly referred to as the 'Bonjour' protocols after 819 their naming by Apple, provide the means for devices to discover 820 services within a local link and, in the absence of a unicast DNS 821 service, to exchange naming information. 823 Where devices are to be deployed in networks where service dicovery 824 would be beneficial, e.g., for users seeking to discover printers or 825 display devices, mDNS and DNS-SD SHOULD be supported. 827 10. IPv4 Support and Transition 829 IPv6 nodes MAY support IPv4. 831 10.1. Transition Mechanisms 833 10.1.1. Basic Transition Mechanisms for IPv6 Hosts and Routers - RFC 834 4213 836 If an IPv6 node implements dual stack and tunneling, then [RFC4213] 837 MUST be supported. 839 11. Application Support 841 11.1. Textual Representation of IPv6 Addresses - RFC 5952 843 Software that allows users and operators to input IPv6 addresses in 844 text form SHOULD support "A Recommendation for IPv6 Address Text 845 Representation" [RFC5952]. 847 11.2. Application Programming Interfaces (APIs) 849 There are a number of IPv6-related APIs. This document does not 850 mandate the use of any, because the choice of API does not directly 851 relate to on-the-wire behavior of protocols. Implementers, however, 852 would be advised to consider providing a common API or reviewing 853 existing APIs for the type of functionality they provide to 854 applications. 856 "Basic Socket Interface Extensions for IPv6" [RFC3493] provides IPv6 857 functionality used by typical applications. Implementers should note 858 that RFC3493 has been picked up and further standardized by the 859 Portable Operating System Interface (POSIX) [POSIX]. 861 "Advanced Sockets Application Program Interface (API) for IPv6" 862 [RFC3542] provides access to advanced IPv6 features needed by 863 diagnostic and other more specialized applications. 865 "IPv6 Socket API for Source Address Selection" [RFC5014] provides 866 facilities that allow an application to override the default Source 867 Address Selection rules of [RFC6724]. 869 "Socket Interface Extensions for Multicast Source Filters" [RFC3678] 870 provides support for expressing source filters on multicast group 871 memberships. 873 "Extension to Sockets API for Mobile IPv6" [RFC4584] provides 874 application support for accessing and enabling Mobile IPv6 [RFC6275] 875 features. 877 12. Mobility 879 Mobile IPv6 [RFC6275] and associated specifications [RFC3776] 880 [RFC4877] allow a node to change its point of attachment within the 881 Internet, while maintaining (and using) a permanent address. All 882 communication using the permanent address continues to proceed as 883 expected even as the node moves around. The definition of Mobile IP 884 includes requirements for the following types of nodes: 886 - mobile nodes 888 - correspondent nodes with support for route optimization 890 - home agents 892 - all IPv6 routers 894 At the present time, Mobile IP has seen only limited implementation 895 and no significant deployment, partly because it originally assumed 896 an IPv6-only environment rather than a mixed IPv4/IPv6 Internet. 897 Recently, additional work has been done to support mobility in mixed- 898 mode IPv4 and IPv6 networks [RFC5555]. 900 More usage and deployment experience is needed with mobility before 901 any specific approach can be recommended for broad implementation in 902 all hosts and routers. Consequently, [RFC6275], [RFC5555], and 903 associated standards such as [RFC4877] are considered a MAY at this 904 time. 906 IPv6 for 3GPP [RFC7066] lists a snapshot of required IPv6 907 Functionalities at the time the document was published that would 908 need to be implemented, going above and beyond the recommendations in 909 this document. Additionally a 3GPP IPv6 Host MAY implement [RFC7278] 910 for delivering IPv6 prefixes on the LAN link. 912 13. Security 914 This section describes the specification for security for IPv6 nodes. 916 Achieving security in practice is a complex undertaking. Operational 917 procedures, protocols, key distribution mechanisms, certificate 918 management approaches, etc., are all components that impact the level 919 of security actually achieved in practice. More importantly, 920 deficiencies or a poor fit in any one individual component can 921 significantly reduce the overall effectiveness of a particular 922 security approach. 924 IPsec either can provide end-to-end security between nodes or or can 925 provide channel security (for example, via a site-to-site IPsec VPN), 926 making it possible to provide secure communication for all (or a 927 subset of) communication flows at the IP layer between pairs of 928 internet nodes. IPsec has two standard operating modes, Tunnel-mode 929 and Transport-mode. In Tunnel-mode, IPsec provides network-layer 930 security and protects an entire IP packet by encapsulating the 931 orginal IP packet and then pre-pending a new IP header. In 932 Transport-mode, IPsec provides security for the transport-layer (and 933 above) by encapsulating only the transport-layer (and above) portion 934 of the IP packet (i.e., without adding a 2nd IP header). 936 Although IPsec can be used with manual keying in some cases, such 937 usage has limited applicability and is not recommended. 939 A range of security technologies and approaches proliferate today 940 (e.g., IPsec, Transport Layer Security (TLS), Secure SHell (SSH), TLS 941 VPNS, etc.) No one approach has emerged as an ideal technology for 942 all needs and environments. Moreover, IPsec is not viewed as the 943 ideal security technology in all cases and is unlikely to displace 944 the others. 946 Previously, IPv6 mandated implementation of IPsec and recommended the 947 key management approach of IKE. This document updates that 948 recommendation by making support of the IPsec Architecture [RFC4301] 949 a SHOULD for all IPv6 nodes. Note that the IPsec Architecture 950 requires (e.g., Section 4.5 of RFC 4301) the implementation of both 951 manual and automatic key management. Currently, the recommended 952 automated key management protocol to implement is IKEv2 [RFC7296]. 954 This document recognizes that there exists a range of device types 955 and environments where approaches to security other than IPsec can be 956 justified. For example, special-purpose devices may support only a 957 very limited number or type of applications, and an application- 958 specific security approach may be sufficient for limited management 959 or configuration capabilities. Alternatively, some devices may run 960 on extremely constrained hardware (e.g., sensors) where the full 961 IPsec Architecture is not justified. 963 Because most common platforms now support IPv6 and have it enabled by 964 default, IPv6 security is an issue for networks that are ostensibly 965 IPv4-only; see [RFC7123] for guidance on this area. 967 13.1. Requirements 969 "Security Architecture for the Internet Protocol" [RFC4301] SHOULD be 970 supported by all IPv6 nodes. Note that the IPsec Architecture 971 requires (e.g., Section 4.5 of [RFC4301]) the implementation of both 972 manual and automatic key management. Currently, the default 973 automated key management protocol to implement is IKEv2. As required 974 in [RFC4301], IPv6 nodes implementing the IPsec Architecture MUST 975 implement ESP [RFC4303] and MAY implement AH [RFC4302]. 977 13.2. Transforms and Algorithms 979 The current set of mandatory-to-implement algorithms for the IPsec 980 Architecture are defined in "Cryptographic Algorithm Implementation 981 Requirements For ESP and AH" [RFC8221]. IPv6 nodes implementing the 982 IPsec Architecture MUST conform to the requirements in [RFC8221]. 983 Preferred cryptographic algorithms often change more frequently than 984 security protocols. Therefore, implementations MUST allow for 985 migration to new algorithms, as RFC 8221 is replaced or updated in 986 the future. 988 The current set of mandatory-to-implement algorithms for IKEv2 are 989 defined in "Cryptographic Algorithms for Use in the Internet Key 990 Exchange Version 2 (IKEv2)" [RFC8247]. IPv6 nodes implementing IKEv2 991 MUST conform to the requirements in [RFC8247] and/or any future 992 updates or replacements to [RFC8247]. 994 14. Router-Specific Functionality 996 This section defines general host considerations for IPv6 nodes that 997 act as routers. Currently, this section does not discuss detailed 998 routing-specific requirements. For the case of typical home routers, 999 [RFC7084] defines basic requirements for customer edge routers. 1001 14.1. IPv6 Router Alert Option - RFC 2711 1003 The IPv6 Router Alert Option [RFC2711] is an optional IPv6 Hop-by-Hop 1004 Header that is used in conjunction with some protocols (e.g., RSVP 1005 [RFC2205] or Multicast Listener Discovery (MLDv2) [RFC3810]). The 1006 Router Alert option will need to be implemented whenever such 1007 protocols that mandate its use are implemented. See Section 5.11. 1009 14.2. Neighbor Discovery for IPv6 - RFC 4861 1011 Sending Router Advertisements and processing Router Solicitations 1012 MUST be supported. 1014 Section 7 of [RFC6275] includes some mobility-specific extensions to 1015 Neighbor Discovery. Routers SHOULD implement Sections 7.3 and 7.5, 1016 even if they do not implement Home Agent functionality. 1018 14.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 1020 A single DHCP server ([RFC3315] or [RFC4862]) can provide 1021 configuration information to devices directly attached to a shared 1022 link, as well as to devices located elsewhere within a site. 1023 Communication between a client and a DHCP server located on different 1024 links requires the use of DHCP relay agents on routers. 1026 In simple deployments, consisting of a single router and either a 1027 single LAN or multiple LANs attached to the single router, together 1028 with a WAN connection, a DHCP server embedded within the router is 1029 one common deployment scenario (e.g., [RFC7084]). There is no need 1030 for relay agents in such scenarios. 1032 In more complex deployment scenarios, such as within enterprise or 1033 service provider networks, the use of DHCP requires some level of 1034 configuration, in order to configure relay agents, DHCP servers, etc. 1035 In such environments, the DHCP server might even be run on a 1036 traditional server, rather than as part of a router. 1038 Because of the wide range of deployment scenarios, support for DHCP 1039 server functionality on routers is optional. However, routers 1040 targeted for deployment within more complex scenarios (as described 1041 above) SHOULD support relay agent functionality. Note that "Basic 1042 Requirements for IPv6 Customer Edge Routers" [RFC7084] requires 1043 implementation of a DHCPv6 server function in IPv6 Customer Edge (CE) 1044 routers. 1046 14.4. IPv6 Prefix Length Recommendation for Forwarding - BCP 198 1048 Forwarding nodes MUST conform to BCP 198 [RFC7608] and thus IPv6 1049 implementations of nodes that may forward packets MUST conform to the 1050 rules specified in Section 5.1 of [RFC4632]. 1052 15. Constrained Devices 1054 The target for this document is general IPv6 nodes. In this Section, 1055 we briefly discuss considerations for constrained devices. 1057 In the case of constrained nodes, with limited CPU, memory, bandwidth 1058 or power, support for certain IPv6 functionality may need to be 1059 considered due to those limitations. While the requirements of this 1060 document are RECOMMENDED for all nodes, including constrained nodes, 1061 compromises may need to be made in certain cases. Where such 1062 compromises are made, the interoperability of devices should be 1063 strongly considered, paticularly where this may impact other nodes on 1064 the same link, e.g., only supporting MLDv1 will affect other nodes. 1066 The IETF 6LowPAN (IPv6 over Low Power LWPAN) WG defined six RFCs, 1067 including a general overview and problem statement ([RFC4919], the 1068 means by which IPv6 packets are transmitted over IEEE 802.15.4 1069 networks [RFC4944] and ND optimisations for that medium [RFC6775]. 1071 IPv6 nodes that are battery-powered SHOULD implement the 1072 recommendations in [RFC7772]. 1074 16. IPv6 Node Management 1076 Network management MAY be supported by IPv6 nodes. However, for IPv6 1077 nodes that are embedded devices, network management may be the only 1078 possible way of controlling these nodes. 1080 Existing network management protocols include SNMP [RFC3411], NETCONF 1081 [RFC6241] and RESTCONF [RFC8040]. 1083 16.1. Management Information Base (MIB) Modules 1085 [RFC8096] clarifies the obsoleted status of various IPv6-specific MIB 1086 modules. 1088 The following two MIB modules SHOULD be supported by nodes that 1089 support a Simple Network Management Protocol (SNMP) agent. 1091 16.1.1. IP Forwarding Table MIB 1093 The IP Forwarding Table MIB [RFC4292] SHOULD be supported by nodes 1094 that support an SNMP agent. 1096 16.1.2. Management Information Base for the Internet Protocol (IP) 1098 The IP MIB [RFC4293] SHOULD be supported by nodes that support an 1099 SNMP agent. 1101 16.1.3. Interface MIB 1103 The Interface MIB [RFC2863] SHOULD be supported by nodes the support 1104 an SNMP agent. 1106 16.2. YANG Data Models 1108 The following YANG data models SHOULD be supported by nodes that 1109 support a NETCONF or RESTCONF agent. 1111 16.2.1. IP Management YANG Model 1113 The IP Management YANG Model [I-D.ietf-netmod-rfc7277bis] SHOULD be 1114 supported by nodes that support NETCONF or RESTCONF. 1116 16.2.2. Interface Management YANG Model 1118 The Interface Management YANG Model [I-D.ietf-netmod-rfc7223bis] 1119 SHOULD be supported by nodes that support NETCONF or RESTCONF. 1121 17. Security Considerations 1123 This document does not directly affect the security of the Internet, 1124 beyond the security considerations associated with the individual 1125 protocols. 1127 Security is also discussed in Section 13 above. 1129 18. IANA Considerations 1131 This document does not require any IANA actions. 1133 19. Authors and Acknowledgments 1134 19.1. Authors and Acknowledgments (Current Document) 1136 For this version of the IPv6 Node Requirements document, the authors 1137 would like to thank Brian Carpenter, Dave Thaler, Tom Herbert, Erik 1138 Kline, Mohamed Boucadair, and Michayla Newcombe for their 1139 contributions. 1141 19.2. Authors and Acknowledgments from RFC 6434 1143 Ed Jankiewicz and Thomas Narten were named authors of the previous 1144 iteration of this document, RFC6434. 1146 For this version of the document, the authors thanked Hitoshi Asaeda, 1147 Brian Carpenter, Tim Chown, Ralph Droms, Sheila Frankel, Sam Hartman, 1148 Bob Hinden, Paul Hoffman, Pekka Savola, Yaron Sheffer, and Dave 1149 Thaler. 1151 19.3. Authors and Acknowledgments from RFC 4294 1153 The original version of this document (RFC 4294) was written by the 1154 IPv6 Node Requirements design team, which had the following members: 1155 Jari Arkko, Marc Blanchet, Samita Chakrabarti, Alain Durand, Gerard 1156 Gastaud, Jun-ichiro Itojun Hagino, Atsushi Inoue, Masahiro Ishiyama, 1157 John Loughney, Rajiv Raghunarayan, Shoichi Sakane, Dave Thaler, and 1158 Juha Wiljakka. 1160 The authors would like to thank Ran Atkinson, Jim Bound, Brian 1161 Carpenter, Ralph Droms, Christian Huitema, Adam Machalek, Thomas 1162 Narten, Juha Ollila, and Pekka Savola for their comments. Thanks to 1163 Mark Andrews for comments and corrections on DNS text. Thanks to 1164 Alfred Hoenes for tracking the updates to various RFCs. 1166 20. Appendix: Changes from RFC 6434 1168 There have been many editorial clarifications as well as significant 1169 additions and updates. While this section highlights some of the 1170 changes, readers should not rely on this section for a comprehensive 1171 list of all changes. 1173 1. Restructured sections 1175 2. Added 6LoWPAN to link layers as it has some deployment. 1177 3. Removed DOD IPv6 Profile as it hasn't been updated. 1179 4. Updated to MLDv2 support to a MUST since nodes are restricted if 1180 MLDv1 is used. 1182 5. Require DNS RA Options so SLAAC-only devices can get DNS, 1183 RFC8106 is a MUST. 1185 6. Require RFC3646 DNS Options for DHCPv6 implementations. 1187 7. Added RESTCONF and NETCONF as possible options to Network 1188 management. 1190 8. Added section on constrained devices. 1192 9. Added text on RFC7934, address availability to hosts (SHOULD). 1194 10. Added text on RFC7844, anonymity profiles for DHCPv6 clients. 1196 11. mDNS and DNS-SD added as updated service discovery. 1198 12. Added RFC8028 as a SHOULD as a method for solving multi-prefix 1199 network 1201 13. Added ECN RFC3168 as a SHOULD 1203 14. Added reference to RFC7123 for Security over IPv4-only networks 1205 15. Removed Jumbograms RFC2675 as they aren't deployed. 1207 16. Updated Obseleted RFCs to the new version of the RFC including 1208 2460, 1981, 7321, 4307 1210 17. Added RFC7772 for power comsumptions considerations 1212 18. Added why /64 boundries for more detail - RFC 7421 1214 19. Added a Unique IPv6 Prefix per Host to support currently 1215 deployed IPv6 networks 1217 20. Clarified RFC7066 was snapshot for 3GPP 1219 21. Updated 4191 as a MUST, SHOULD for Type C Host as it helps solve 1220 multi-prefix problem 1222 22. Removed IPv6 over ATM since there aren't many deployments 1224 23. Added a note in Section 6.6 for RFC6724 Section 5.5/ 1226 24. Added MUST for BCP 198 for forwarding IPv6 packets 1228 25. Added reference to RFC8064 for stable address creation. 1230 26. Added text on protection from excessive EH options 1232 27. Added text on dangers of 1280 MTU UDP, esp. wrt DNS traffic 1234 28. Added text to clarify RFC8200 behaviour for unrecognized EHs or 1235 unrecognized ULPs 1237 29. Removed dated email addresses from design team acknowledgements 1238 for RFC 4294. 1240 21. Appendix: Changes from RFC 4294 1242 There have been many editorial clarifications as well as significant 1243 additions and updates. While this section highlights some of the 1244 changes, readers should not rely on this section for a comprehensive 1245 list of all changes. 1247 1. Updated the Introduction to indicate that this document is an 1248 applicability statement and is aimed at general nodes. 1250 2. Significantly updated the section on Mobility protocols, adding 1251 references and downgrading previous SHOULDs to MAYs. 1253 3. Changed Sub-IP Layer section to just list relevant RFCs, and 1254 added some more RFCs. 1256 4. Added section on SEND (it is a MAY). 1258 5. Revised section on Privacy Extensions [RFC4941] to add more 1259 nuance to recommendation. 1261 6. Completely revised IPsec/IKEv2 section, downgrading overall 1262 recommendation to a SHOULD. 1264 7. Upgraded recommendation of DHCPv6 to SHOULD. 1266 8. Added background section on DHCP versus RA options, added SHOULD 1267 recommendation for DNS configuration via RAs (RFC6106), and 1268 cleaned up DHCP recommendations. 1270 9. Added recommendation that routers implement Sections 7.3 and 7.5 1271 of [RFC6275]. 1273 10. Added pointer to subnet clarification document [RFC5942]. 1275 11. Added text that "IPv6 Host-to-Router Load Sharing" [RFC4311] 1276 SHOULD be implemented. 1278 12. Added reference to [RFC5722] (Overlapping Fragments), and made 1279 it a MUST to implement. 1281 13. Made "A Recommendation for IPv6 Address Text Representation" 1282 [RFC5952] a SHOULD. 1284 14. Removed mention of "DNAME" from the discussion about [RFC3363]. 1286 15. Numerous updates to reflect newer versions of IPv6 documents, 1287 including [RFC4443], [RFC4291], [RFC3596], and [RFC4213]. 1289 16. Removed discussion of "Managed" and "Other" flags in RAs. There 1290 is no consensus at present on how to process these flags, and 1291 discussion of their semantics was removed in the most recent 1292 update of Stateless Address Autoconfiguration [RFC4862]. 1294 17. Added many more references to optional IPv6 documents. 1296 18. Made "A Recommendation for IPv6 Address Text Representation" 1297 [RFC5952] a SHOULD. 1299 19. Added reference to [RFC5722] (Overlapping Fragments), and made 1300 it a MUST to implement. 1302 20. Updated MLD section to include reference to Lightweight MLD 1303 [RFC5790]. 1305 21. Added SHOULD recommendation for "Default Router Preferences and 1306 More-Specific Routes" [RFC4191]. 1308 22. Made "IPv6 Flow Label Specification" [RFC6437] a SHOULD. 1310 22. References 1312 22.1. Normative References 1314 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1315 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1316 . 1318 [RFC1035] Mockapetris, P., "Domain names - implementation and 1319 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1320 November 1987, . 1322 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1323 Requirement Levels", BCP 14, RFC 2119, 1324 DOI 10.17487/RFC2119, March 1997, 1325 . 1327 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1328 Listener Discovery (MLD) for IPv6", RFC 2710, 1329 DOI 10.17487/RFC2710, October 1999, 1330 . 1332 [RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", 1333 RFC 2711, DOI 10.17487/RFC2711, October 1999, 1334 . 1336 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 1337 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 1338 . 1340 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 1341 of Explicit Congestion Notification (ECN) to IP", 1342 RFC 3168, DOI 10.17487/RFC3168, September 2001, 1343 . 1345 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1346 C., and M. Carney, "Dynamic Host Configuration Protocol 1347 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1348 2003, . 1350 [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An 1351 Architecture for Describing Simple Network Management 1352 Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, 1353 DOI 10.17487/RFC3411, December 2002, 1354 . 1356 [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 1357 "DNS Extensions to Support IP Version 6", STD 88, 1358 RFC 3596, DOI 10.17487/RFC3596, October 2003, 1359 . 1361 [RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol 1362 (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736, 1363 April 2004, . 1365 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1366 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1367 DOI 10.17487/RFC3810, June 2004, 1368 . 1370 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1371 Rose, "DNS Security Introduction and Requirements", 1372 RFC 4033, DOI 10.17487/RFC4033, March 2005, 1373 . 1375 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1376 Rose, "Resource Records for the DNS Security Extensions", 1377 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1378 . 1380 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1381 Rose, "Protocol Modifications for the DNS Security 1382 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, 1383 . 1385 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1386 for IPv6 Hosts and Routers", RFC 4213, 1387 DOI 10.17487/RFC4213, October 2005, 1388 . 1390 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1391 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1392 2006, . 1394 [RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, 1395 DOI 10.17487/RFC4292, April 2006, 1396 . 1398 [RFC4293] Routhier, S., Ed., "Management Information Base for the 1399 Internet Protocol (IP)", RFC 4293, DOI 10.17487/RFC4293, 1400 April 2006, . 1402 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1403 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 1404 December 2005, . 1406 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1407 RFC 4303, DOI 10.17487/RFC4303, December 2005, 1408 . 1410 [RFC4311] Hinden, R. and D. Thaler, "IPv6 Host-to-Router Load 1411 Sharing", RFC 4311, DOI 10.17487/RFC4311, November 2005, 1412 . 1414 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1415 Control Message Protocol (ICMPv6) for the Internet 1416 Protocol Version 6 (IPv6) Specification", STD 89, 1417 RFC 4443, DOI 10.17487/RFC4443, March 2006, 1418 . 1420 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 1421 IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, 1422 . 1424 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 1425 (CIDR): The Internet Address Assignment and Aggregation 1426 Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August 1427 2006, . 1429 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1430 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1431 DOI 10.17487/RFC4861, September 2007, 1432 . 1434 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1435 Address Autoconfiguration", RFC 4862, 1436 DOI 10.17487/RFC4862, September 2007, 1437 . 1439 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 1440 Extensions for Stateless Address Autoconfiguration in 1441 IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, 1442 . 1444 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 1445 of Type 0 Routing Headers in IPv6", RFC 5095, 1446 DOI 10.17487/RFC5095, December 2007, 1447 . 1449 [RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers", 1450 RFC 5453, DOI 10.17487/RFC5453, February 2009, 1451 . 1453 [RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", 1454 RFC 5722, DOI 10.17487/RFC5722, December 2009, 1455 . 1457 [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 1458 Group Management Protocol Version 3 (IGMPv3) and Multicast 1459 Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, 1460 DOI 10.17487/RFC5790, February 2010, 1461 . 1463 [RFC5942] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet 1464 Model: The Relationship between Links and Subnet 1465 Prefixes", RFC 5942, DOI 10.17487/RFC5942, July 2010, 1466 . 1468 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 1469 Address Text Representation", RFC 5952, 1470 DOI 10.17487/RFC5952, August 2010, 1471 . 1473 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 1474 and A. Bierman, Ed., "Network Configuration Protocol 1475 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 1476 . 1478 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 1479 "IPv6 Flow Label Specification", RFC 6437, 1480 DOI 10.17487/RFC6437, November 2011, 1481 . 1483 [RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and 1484 M. Bhatia, "A Uniform Format for IPv6 Extension Headers", 1485 RFC 6564, DOI 10.17487/RFC6564, April 2012, 1486 . 1488 [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, 1489 "Default Address Selection for Internet Protocol Version 6 1490 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, 1491 . 1493 [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, 1494 DOI 10.17487/RFC6762, February 2013, 1495 . 1497 [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service 1498 Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, 1499 . 1501 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1502 Bormann, "Neighbor Discovery Optimization for IPv6 over 1503 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1504 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1505 . 1507 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 1508 for DNS (EDNS(0))", STD 75, RFC 6891, 1509 DOI 10.17487/RFC6891, April 2013, 1510 . 1512 [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", 1513 RFC 6946, DOI 10.17487/RFC6946, May 2013, 1514 . 1516 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 1517 of IPv6 Extension Headers", RFC 7045, 1518 DOI 10.17487/RFC7045, December 2013, 1519 . 1521 [RFC7048] Nordmark, E. and I. Gashinsky, "Neighbor Unreachability 1522 Detection Is Too Impatient", RFC 7048, 1523 DOI 10.17487/RFC7048, January 2014, 1524 . 1526 [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of 1527 Oversized IPv6 Header Chains", RFC 7112, 1528 DOI 10.17487/RFC7112, January 2014, 1529 . 1531 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 1532 Interface Identifiers with IPv6 Stateless Address 1533 Autoconfiguration (SLAAC)", RFC 7217, 1534 DOI 10.17487/RFC7217, April 2014, 1535 . 1537 [I-D.ietf-netmod-rfc7223bis] 1538 Bjorklund, M., "A YANG Data Model for Interface 1539 Management", draft-ietf-netmod-rfc7223bis-03 (work in 1540 progress), January 2018. 1542 [I-D.ietf-netmod-rfc7277bis] 1543 Bjorklund, M., "A YANG Data Model for IP Management", 1544 draft-ietf-netmod-rfc7277bis-03 (work in progress), 1545 January 2018. 1547 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 1548 Kivinen, "Internet Key Exchange Protocol Version 2 1549 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 1550 2014, . 1552 [RFC7527] Asati, R., Singh, H., Beebee, W., Pignataro, C., Dart, E., 1553 and W. George, "Enhanced Duplicate Address Detection", 1554 RFC 7527, DOI 10.17487/RFC7527, April 2015, 1555 . 1557 [RFC7559] Krishnan, S., Anipko, D., and D. Thaler, "Packet-Loss 1558 Resiliency for Router Solicitations", RFC 7559, 1559 DOI 10.17487/RFC7559, May 2015, 1560 . 1562 [RFC7608] Boucadair, M., Petrescu, A., and F. Baker, "IPv6 Prefix 1563 Length Recommendation for Forwarding", BCP 198, RFC 7608, 1564 DOI 10.17487/RFC7608, July 2015, 1565 . 1567 [RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6 1568 Atomic Fragments Considered Harmful", RFC 8021, 1569 DOI 10.17487/RFC8021, January 2017, 1570 . 1572 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 1573 Hosts in a Multi-Prefix Network", RFC 8028, 1574 DOI 10.17487/RFC8028, November 2016, 1575 . 1577 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 1578 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 1579 . 1581 [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, 1582 "Recommendation on Stable IPv6 Interface Identifiers", 1583 RFC 8064, DOI 10.17487/RFC8064, February 2017, 1584 . 1586 [RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 1587 "IPv6 Router Advertisement Options for DNS Configuration", 1588 RFC 8106, DOI 10.17487/RFC8106, March 2017, 1589 . 1591 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1592 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1593 May 2017, . 1595 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1596 (IPv6) Specification", STD 86, RFC 8200, 1597 DOI 10.17487/RFC8200, July 2017, 1598 . 1600 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1601 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1602 DOI 10.17487/RFC8201, July 2017, 1603 . 1605 [RFC8221] Wouters, P., Migault, D., Mattsson, J., Nir, Y., and T. 1606 Kivinen, "Cryptographic Algorithm Implementation 1607 Requirements and Usage Guidance for Encapsulating Security 1608 Payload (ESP) and Authentication Header (AH)", RFC 8221, 1609 DOI 10.17487/RFC8221, October 2017, 1610 . 1612 [RFC8247] Nir, Y., Kivinen, T., Wouters, P., and D. Migault, 1613 "Algorithm Implementation Requirements and Usage Guidance 1614 for the Internet Key Exchange Protocol Version 2 (IKEv2)", 1615 RFC 8247, DOI 10.17487/RFC8247, September 2017, 1616 . 1618 22.2. Informative References 1620 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 1621 RFC 793, DOI 10.17487/RFC0793, September 1981, 1622 . 1624 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 1625 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 1626 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 1627 September 1997, . 1629 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1630 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1631 . 1633 [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 1634 over Non-Broadcast Multiple Access (NBMA) networks", 1635 RFC 2491, DOI 10.17487/RFC2491, January 1999, 1636 . 1638 [RFC2590] Conta, A., Malis, A., and M. Mueller, "Transmission of 1639 IPv6 Packets over Frame Relay Networks Specification", 1640 RFC 2590, DOI 10.17487/RFC2590, May 1999, 1641 . 1643 [RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", 1644 RFC 2923, DOI 10.17487/RFC2923, September 2000, 1645 . 1647 [RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets 1648 over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146, 1649 October 2001, . 1651 [RFC3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. 1652 Hain, "Representing Internet Protocol version 6 (IPv6) 1653 Addresses in the Domain Name System (DNS)", RFC 3363, 1654 DOI 10.17487/RFC3363, August 2002, 1655 . 1657 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 1658 Stevens, "Basic Socket Interface Extensions for IPv6", 1659 RFC 3493, DOI 10.17487/RFC3493, February 2003, 1660 . 1662 [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, 1663 "Advanced Sockets Application Program Interface (API) for 1664 IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003, 1665 . 1667 [RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic 1668 Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, 1669 DOI 10.17487/RFC3646, December 2003, 1670 . 1672 [RFC3678] Thaler, D., Fenner, B., and B. Quinn, "Socket Interface 1673 Extensions for Multicast Source Filters", RFC 3678, 1674 DOI 10.17487/RFC3678, January 2004, 1675 . 1677 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1678 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1679 2011, . 1681 [RFC3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to 1682 Protect Mobile IPv6 Signaling Between Mobile Nodes and 1683 Home Agents", RFC 3776, DOI 10.17487/RFC3776, June 2004, 1684 . 1686 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 1687 "SEcure Neighbor Discovery (SEND)", RFC 3971, 1688 DOI 10.17487/RFC3971, March 2005, 1689 . 1691 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 1692 RFC 3972, DOI 10.17487/RFC3972, March 2005, 1693 . 1695 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 1696 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 1697 November 2005, . 1699 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 1700 DOI 10.17487/RFC4302, December 2005, 1701 . 1703 [RFC4338] DeSanti, C., Carlson, C., and R. Nixon, "Transmission of 1704 IPv6, IPv4, and Address Resolution Protocol (ARP) Packets 1705 over Fibre Channel", RFC 4338, DOI 10.17487/RFC4338, 1706 January 2006, . 1708 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 1709 Network Address Translations (NATs)", RFC 4380, 1710 DOI 10.17487/RFC4380, February 2006, 1711 . 1713 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1714 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1715 . 1717 [RFC4584] Chakrabarti, S. and E. Nordmark, "Extension to Sockets API 1718 for Mobile IPv6", RFC 4584, DOI 10.17487/RFC4584, July 1719 2006, . 1721 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 1722 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 1723 . 1725 [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 1726 IKEv2 and the Revised IPsec Architecture", RFC 4877, 1727 DOI 10.17487/RFC4877, April 2007, 1728 . 1730 [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, 1731 "Extended ICMP to Support Multi-Part Messages", RFC 4884, 1732 DOI 10.17487/RFC4884, April 2007, 1733 . 1735 [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering 1736 ICMPv6 Messages in Firewalls", RFC 4890, 1737 DOI 10.17487/RFC4890, May 2007, 1738 . 1740 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 1741 over Low-Power Wireless Personal Area Networks (6LoWPANs): 1742 Overview, Assumptions, Problem Statement, and Goals", 1743 RFC 4919, DOI 10.17487/RFC4919, August 2007, 1744 . 1746 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 1747 "Transmission of IPv6 Packets over IEEE 802.15.4 1748 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 1749 . 1751 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 1752 Socket API for Source Address Selection", RFC 5014, 1753 DOI 10.17487/RFC5014, September 2007, 1754 . 1756 [RFC5072] Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6 1757 over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007, 1758 . 1760 [RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S. 1761 Madanapalli, "Transmission of IPv6 via the IPv6 1762 Convergence Sublayer over IEEE 802.16 Networks", RFC 5121, 1763 DOI 10.17487/RFC5121, February 2008, 1764 . 1766 [RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack 1767 Hosts and Routers", RFC 5555, DOI 10.17487/RFC5555, June 1768 2009, . 1770 [RFC6563] Jiang, S., Conrad, D., and B. Carpenter, "Moving A6 to 1771 Historic Status", RFC 6563, DOI 10.17487/RFC6563, March 1772 2012, . 1774 [RFC7066] Korhonen, J., Ed., Arkko, J., Ed., Savolainen, T., and S. 1775 Krishnan, "IPv6 for Third Generation Partnership Project 1776 (3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066, 1777 November 2013, . 1779 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1780 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1781 DOI 10.17487/RFC7084, November 2013, 1782 . 1784 [RFC7123] Gont, F. and W. Liu, "Security Implications of IPv6 on 1785 IPv4 Networks", RFC 7123, DOI 10.17487/RFC7123, February 1786 2014, . 1788 [RFC7278] Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6 1789 /64 Prefix from a Third Generation Partnership Project 1790 (3GPP) Mobile Interface to a LAN Link", RFC 7278, 1791 DOI 10.17487/RFC7278, June 2014, 1792 . 1794 [RFC7371] Boucadair, M. and S. Venaas, "Updates to the IPv6 1795 Multicast Addressing Architecture", RFC 7371, 1796 DOI 10.17487/RFC7371, September 2014, 1797 . 1799 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1800 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1801 Boundary in IPv6 Addressing", RFC 7421, 1802 DOI 10.17487/RFC7421, January 2015, 1803 . 1805 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 1806 Considerations for IPv6 Address Generation Mechanisms", 1807 RFC 7721, DOI 10.17487/RFC7721, March 2016, 1808 . 1810 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 1811 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 1812 February 2016, . 1814 [RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy 1815 Consumption of Router Advertisements", BCP 202, RFC 7772, 1816 DOI 10.17487/RFC7772, February 2016, 1817 . 1819 [RFC7844] Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity 1820 Profiles for DHCP Clients", RFC 7844, 1821 DOI 10.17487/RFC7844, May 2016, 1822 . 1824 [RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi, 1825 "Host Address Availability Recommendations", BCP 204, 1826 RFC 7934, DOI 10.17487/RFC7934, July 2016, 1827 . 1829 [RFC8087] Fairhurst, G. and M. Welzl, "The Benefits of Using 1830 Explicit Congestion Notification (ECN)", RFC 8087, 1831 DOI 10.17487/RFC8087, March 2017, 1832 . 1834 [RFC8096] Fenner, B., "The IPv6-Specific MIB Modules Are Obsolete", 1835 RFC 8096, DOI 10.17487/RFC8096, April 2017, 1836 . 1838 [RFC8273] Brzozowski, J. and G. Van de Velde, "Unique IPv6 Prefix 1839 per Host", RFC 8273, DOI 10.17487/RFC8273, December 2017, 1840 . 1842 [POSIX] IEEE, "IEEE Std. 1003.1-2008 Standard for Information 1843 Technology -- Portable Operating System Interface (POSIX), 1844 ISO/IEC 9945:2009", . 1846 [USGv6] National Institute of Standards and Technology, "A Profile 1847 for IPv6 in the U.S. Government - Version 1.0", July 2008, 1848 . 1850 Authors' Addresses 1852 Tim Chown 1853 Jisc 1854 Lumen House, Library Avenue 1855 Harwell Oxford, Didcot OX11 0SG 1856 United Kingdom 1858 Email: tim.chown@jisc.ac.uk 1860 John Loughney 1861 Intel 1862 Santa Clara, CA 1863 USA 1865 Email: john.loughney@gmail.com 1867 Timothy Winters 1868 University of New Hampshire, Interoperability Lab (UNH-IOL) 1869 Durham, NH 1870 United States 1872 Email: twinters@iol.unh.edu