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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Cotton 3 Internet-Draft ICANN 4 BCP: 26 B. Leiba 5 Obsoletes: 5226 (if approved) Huawei Technologies 6 Intended status: Best Current Practice T. Narten 7 Expires: November 29, 2016 IBM Corporation 8 May 30, 2016 10 Guidelines for Writing an IANA Considerations Section in RFCs 11 draft-leiba-cotton-iana-5226bis-14 13 Abstract 15 Many protocols make use of points of extensibility that use constants 16 to identify various protocol parameters. To ensure that the values 17 used in these fields do not have conflicting uses, and to promote 18 interoperability, their allocation is often coordinated by a central 19 record keeper. For IETF protocols, that role is filled by the 20 Internet Assigned Numbers Authority (IANA). 22 To make assignments in a given registry prudently, IANA needs 23 guidance describing the conditions under which new values should be 24 assigned, as well as when and how modifications to existing values 25 can be made. This document defines a framework for the documentation 26 of these guidelines by specification authors, in order to assure that 27 the guidance given to IANA is clear and addresses the various issues 28 that are likely in the operation of a registry. 30 This is the third edition of this document; it obsoletes RFC 5226. 32 Status of this Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on November 29, 2016. 49 Copyright Notice 51 Copyright (c) 2016 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents (http://trustee.ietf.org/ 56 license-info) in effect on the date of publication of this document. 57 Please review these documents carefully, as they describe your rights 58 and restrictions with respect to this document. Code Components 59 extracted from this document must include Simplified BSD License text 60 as described in Section 4.e of the Trust Legal Provisions and are 61 provided without warranty as described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 1.1. Keep IANA Considerations for IANA . . . . . . . . . . . . 3 67 1.2. For More Information . . . . . . . . . . . . . . . . . . . 4 68 2. Creating and Revising Registries . . . . . . . . . . . . . . . 4 69 2.1. Organization of Registries . . . . . . . . . . . . . . . . 4 70 2.2. Documentation Requirements for Registries . . . . . . . . 6 71 2.3. Specifying Change Control for a Registry . . . . . . . . . 8 72 2.4. Revising Existing Registries . . . . . . . . . . . . . . . 9 73 3. Registering New Values in an Existing Registry . . . . . . . . 9 74 3.1. Documentation Requirements for Registrations . . . . . . . 9 75 3.2. Updating Existing Registrations . . . . . . . . . . . . . 11 76 3.3. Overriding Registration Procedures . . . . . . . . . . . . 12 77 3.4. Early Allocations . . . . . . . . . . . . . . . . . . . . 12 78 4. Choosing a Registration Policy, and Well-Known Policies . . . 13 79 4.1. Private Use . . . . . . . . . . . . . . . . . . . . . . . 15 80 4.2. Experimental Use . . . . . . . . . . . . . . . . . . . . . 15 81 4.3. Hierarchical Allocation . . . . . . . . . . . . . . . . . 16 82 4.4. First Come First Served . . . . . . . . . . . . . . . . . 16 83 4.5. Expert Review . . . . . . . . . . . . . . . . . . . . . . 17 84 4.6. Specification Required . . . . . . . . . . . . . . . . . . 18 85 4.7. RFC Required . . . . . . . . . . . . . . . . . . . . . . . 19 86 4.8. IETF Review . . . . . . . . . . . . . . . . . . . . . . . 19 87 4.9. Standards Action . . . . . . . . . . . . . . . . . . . . . 20 88 4.10. IESG Approval . . . . . . . . . . . . . . . . . . . . . . 20 89 4.11. Using the Well-Known Registration Policies . . . . . . . . 21 90 4.12. Using Multiple Policies in Combination . . . . . . . . . . 22 91 5. Designated Experts . . . . . . . . . . . . . . . . . . . . . . 23 92 5.1. The Motivation for Designated Experts . . . . . . . . . . 23 93 5.2. The Role of the Designated Expert . . . . . . . . . . . . 23 94 5.2.1. Managing Designated Experts in the IETF . . . . . . . 24 95 5.3. Designated Expert Reviews . . . . . . . . . . . . . . . . 25 96 5.4. Expert Reviews and the Document Lifecycle . . . . . . . . 26 97 6. Well-Known Registration Status Terminology . . . . . . . . . . 27 98 7. Documentation References in IANA Registries . . . . . . . . . 27 99 8. What to Do in "bis" Documents . . . . . . . . . . . . . . . . 28 100 9. Miscellaneous Issues . . . . . . . . . . . . . . . . . . . . . 29 101 9.1. When There Are No IANA Actions . . . . . . . . . . . . . . 29 102 9.2. Namespaces Lacking Documented Guidance . . . . . . . . . . 30 103 9.3. After-the-Fact Registrations . . . . . . . . . . . . . . . 30 104 9.4. Reclaiming Assigned Values . . . . . . . . . . . . . . . . 30 105 9.5. Contact Person vs Assignee or Owner . . . . . . . . . . . 31 106 9.6. Closing or Obsoleting a Registry/Registrations . . . . . . 32 108 10. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 109 11. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . . . 32 110 12. Security Considerations . . . . . . . . . . . . . . . . . . . 32 111 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 112 14. Changes Relative to Earlier Editions of BCP 26 . . . . . . . . 33 113 14.1. 2016: Changes in This Document Relative to RFC 5226 . . . 33 114 14.2. 2008: Changes in RFC 5226 Relative to RFC 2434 . . . . . 34 115 15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35 116 15.1. Acknowledgments for This Document (2016) . . . . . . . . 35 117 15.2. Acknowledgments from the second edition (2008) . . . . . 35 118 15.3. Acknowledgments from the first edition (1998) . . . . . . 35 119 16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36 120 16.1. Normative References . . . . . . . . . . . . . . . . . . 36 121 16.2. Informative References . . . . . . . . . . . . . . . . . 36 122 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39 124 1. Introduction 126 Many protocols make use of points of extensibility that use constants 127 to identify various protocol parameters. To ensure that the values 128 used in these fields do not have conflicting uses, and to promote 129 interoperability, their allocation is often coordinated by a central 130 record keeper. For IETF protocols, that role is filled by the 131 Internet Assigned Numbers Authority (IANA) [RFC2860]. 133 The Protocol field in the IP header [RFC0791] and MIME media types 134 [RFC4288] are two examples of such coordinations. 136 In this document, we call the range of possible values for such a 137 field a "namespace". The binding or association of a specific value 138 with a particular purpose within a namespace is called an assignment 139 (or, variously: an assigned number, assigned value, code point, 140 protocol constant, or protocol parameter). The act of assignment is 141 called a registration, and it takes place in the context of a 142 registry. The terms "assignment" and "registration" are used 143 interchangably throughout this document. 145 To make assignments in a given namespace prudently, IANA needs 146 guidance describing the conditions under which new values should be 147 assigned, as well as when and how modifications to existing values 148 can be made. This document defines a framework for the documentation 149 of these guidelines by specification authors, in order to assure that 150 the guidance given to IANA is clear and addresses the various issues 151 that are likely in the operation of a registry. 153 Typically, this information is recorded in a dedicated section of the 154 specification with the title "IANA Considerations". 156 1.1. Keep IANA Considerations for IANA 157 The purpose of having a dedicated IANA Considerations section is to 158 provide a single place to collect clear and concise information and 159 instructions for IANA. Technical documentation should reside in 160 other parts of the document, and should be included by reference 161 only. Using the IANA Considerations section as primary technical 162 documentation both hides it from the target audience of the document 163 and interferes with IANA's review of the actions they need to take. 165 An ideal IANA Considerations section clearly enumerates and specifies 166 each requested IANA action; includes all information IANA needs, such 167 as the full names of all applicable registries; and includes clear 168 references to elsewhere in the document for other information. 170 1.2. For More Information 172 IANA maintains a web page that includes current important information 173 from IANA. Document authors should check that page for additional 174 information, beyond what is provided here. 176 . 178 [[(RFC Editor: Please remove this paragraph.) The initial version of 179 this should contain the bits that are salient to most document 180 authors -- perhaps a table of required elements to create a new 181 registry or update one, a bit about sub-registries, and the listing 182 of well-known registration policies. IANA has text for this, but 183 they need to work on their process to put the page up (transition 184 issues). We might host the first version on the IETF site, with the 185 URL above set to redirect to it. ]] 187 2. Creating and Revising Registries 189 Defining a registry involves describing the namespaces to be created, 190 listing an initial set of assignments (if applicable), and 191 documenting guidelines on how future assignments are to be made. 193 When defining a registry, consider structuring the namespace in such 194 a way that only top-level assignments need to be made with central 195 coordination, and those assignments can delegate lower-level 196 assignments so coordination for them can be distributed. This 197 lessens the burden on IANA for dealing with assignments, and is 198 particularly useful in situations where distributed coordinators have 199 better knowledge of their portion of the namespace and are better 200 suited to handling those assignments. 202 2.1. Organization of Registries 204 All registries are anchored from the IANA "Protocol Registries" page: 206 . 208 That page lists registries in protocol category groups, like this: 210 --------------------------------------------------------------- 211 Author Domain Signing Practices (ADSP) Parameters 213 ADSP Outbound Signing Practices RFC 5617 214 IETF Review 216 ADSP Specification Tags RFC 5617 217 IETF Review 219 Automatic Responses to Electronic Mail Parameters 221 Auto-Submitted Header Field RFC 5436 222 Keywords Specification Required 224 Auto-Submitted header field RFC 3834 225 optional parameters IETF Consensus 227 Autonomous System (AS) Numbers 229 16-bit Autonomous System Numbers RFC 1930, RFC 5398, RFC 6996 230 RIR request to the IANA 231 or IETF Review 233 32-bit Autonomous System Numbers RFC 1930, RFC 5398, RFC 6793, 234 RFC 6996 235 RIR request to the IANA 236 or IETF Review 237 --------------------------------------------------------------- 239 The grouping allows related registries to be placed together, making 240 it easier for users of the registries to find the necessary 241 information. In the example section above, all registries related to 242 the ADSP protocol are placed in the "ADSP Parameters" group. 244 Within the "ADSP Parameters" group are two registries: "ADSP Outbound 245 Signing Practices" and "ADSP Specification Tags". Clicking on the 246 title of one of these registries on the IANA Protocol Registries page 247 will take the reader to the details page for that registry. Often, 248 multiple registries are shown on the same details page. 250 Unfortunately, we have been inconsistent in how we refer to these 251 entities. The group names, as they are referred to here, have been 252 variously called "protocol category groups", "groups", "top-level 253 registries", or just "registries". The registries under them have 254 been called "registries" or "sub-registries". 256 Regardless of the terminology used, document authors should pay 257 attention to the registry groupings, should request that related 258 registries be grouped together to make related registries easier to 259 find, and, when creating a new registry, should check whether that 260 registry might best be included in an existing group. That grouping 261 information should be clearly communicated to IANA in the registry 262 creation request. 264 2.2. Documentation Requirements for Registries 266 Documents that create a new namespace (or modify the definition of an 267 existing space) and that expect IANA to play a role in maintaining 268 that space (serving as a repository for registered values) must 269 provide clear instructions on details of the namespace, either in the 270 IANA Considerations section, or referenced from it. 272 In particular, such instructions must include: 274 The name of the registry 275 This name will appear on the IANA web page and will be referred to 276 in future documents that need to allocate a value from the new 277 space. The full name (and abbreviation, if appropriate) should be 278 provided. It is highly desirable that the chosen name not be 279 easily confused with the name of another registry. 281 When creating a registry, the group that it is a part of must be 282 identified using its full name, exactly as it appears in the IANA 283 registry list. 285 Providing a URL to precisely identify the registry helps IANA 286 understand the request. Such URLs can be removed from the RFC 287 prior to final publication. If they are to be left in, it is 288 important that they be permanent links. IANA can answer questions 289 about the correct URLs to use. 291 For example, a document could contain something like this: 293 This registration should be made in the Foobar Operational 294 Parameters registry, located at . 297 It might be tempting to use the URL that appears in your web 298 browser's address bar, which might look something like this for 299 the example above: 301 https://www.iana.org/assignments/foobar-registry/foobar- 302 registry.xml 304 ...but that is not the permanent link to the registry. 306 Required information for registrations 307 This tells registrants what information they have to include in 308 their registration requests. Some registries require only the 309 requested value and a reference to a document where use of the 310 value is defined. Other registries require a more detailed 311 registration template that describes relevant security 312 considerations, internationalization considerations, and other 313 such information. 315 Applicable registration policy 317 The policy that will apply to all future requests for 318 registration. See Section 4. 320 Size, format and syntax of registry entries 322 What fields to record in the registry, any technical requirements 323 on registry entries (valid ranges for integers, length limitations 324 on strings, and such), and the exact format in which registry 325 values should be displayed. For numeric assignments, one should 326 specify whether values are to be recorded in decimal, in 327 hexadecimal, or in some other format. 329 Strings are expected to be ASCII, and it should be clearly 330 specified whether case matters, and whether, for example, strings 331 should be shown in the registry in upper case or lower case. 333 Strings that represent protocol parameters will rarely, if ever, 334 need to contain non-ASCII characters. If non-ASCII characters are 335 really necessary, instructions should make it very clear that they 336 are allowed and that the non-ASCII characters should be 337 represented as Unicode characters using the "(U+XXXX)" convention. 338 Anyone creating such a registry should think carefully about this 339 and consider internationalization advice such as that in [RFC7564] 340 Section 10. 342 Initial assignments and reservations 344 Any initial assignments or registrations to be included. In 345 addition, any ranges that are to be reserved for "Private Use", 346 "Reserved", "Unassigned", etc. (see Section 6) should be 347 indicated. 349 For example, a document might specify a new registry by including: 351 --------------------------------------------------------------- 353 X. IANA Considerations 355 This document defines a new DHCP option, entitled "FooBar" (see 356 Section y), assigned a value of TBD1 from the DHCP Option space 357 358 [RFC2132] [RFC2939]: 359 Data 360 Tag Name Length Meaning 361 ---- ---- ------ ------- 362 TBD1 FooBar N FooBar server 364 The FooBar option also defines an 8-bit FooType field, for which 365 IANA is to create and maintain a new registry entitled 366 "FooType values" used by the FooBar option. Initial values for the 367 DHCP FooBar FooType registry are given below; future assignments 368 are to be made through Expert Review [BCP26]. 369 Assignments consist of a DHCP FooBar FooType name and its 370 associated value. 372 Value DHCP FooBar FooType Name Definition 373 ---- ------------------------ ---------- 374 0 Reserved 375 1 Frobnitz RFCXXXX, Section y.1 376 2 NitzFrob RFCXXXX, Section y.2 377 3-254 Unassigned 378 255 Reserved 379 --------------------------------------------------------------- 381 For examples of documents that establish registries, consult 382 [RFC3575], [RFC3968], and [RFC4520]. 384 2.3. Specifying Change Control for a Registry 386 Registry definitions and registrations within registries often need 387 to be changed after they are created. The process of making such 388 changes is complicated when it is unclear who is authorized to make 389 the changes. For registries created by RFCs in the IETF stream, 390 change control for the registry lies by default with the IETF, via 391 the IESG. The same is true for value registrations made in IETF- 392 stream RFCs. 394 Because registries can be created and registrations can be made 395 outside the IETF stream, it can sometimes be desirable to have change 396 control outside the IETF and IESG, and clear specification of change 397 control policies is always helpful. 399 It is advised, therefore, that all registries that are created 400 clearly specify a change control policy and a change controller. It 401 is also advised that registries that allow registrations from outside 402 the IETF stream include, for each value, the designation of a change 403 controller for that value. If the definition or reference for a 404 registered value ever needs to change, or if a registered value needs 405 to be deprecated, it is critical that IANA know who is authorized to 406 make the change. See also Section 9.5. 408 While IANA normally includes information about change control in the 409 public registry, some change controllers might prefer that their 410 identities or contact information not be made public. In such cases, 411 arrangements can be made with IANA to keep the information private, 412 to use an alias or role-based contact address, or to otherwise 413 protect the change controller's privacy. 415 2.4. Revising Existing Registries 417 Updating the registration process or making changes to the format of 418 an already existing (previously created) registry (whether created 419 explicitly or implicitly) follows a process similar to that used when 420 creating a new registry. That is, a document is produced that makes 421 reference to the existing namespace and then provides detailed 422 guidance for handling assignments in the registry, or detailed 423 instructions about the changes required. 425 If a change requires a new column in the registry, the instructions 426 need to be clear about how to populate that column for the existing 427 entries. Other changes may require similar clarity. 429 Such documents are normally processed with the same document status 430 as the document that created the registry. Under some circumstances, 431 such as with a straightforward change that is clearly needed (such as 432 adding a "status" column), or when an earlier error needs to be 433 corrected, the IESG may approve an update to a registry without 434 requiring a new document. 436 Example documents that updated the guidelines for assignments in pre- 437 existing registries include: [RFC6195], [RFC3228], and [RFC3575]. 439 3. Registering New Values in an Existing Registry 441 3.1. Documentation Requirements for Registrations 443 Often, documents request an assignment in an existing registry (one 444 created by a previously published document). 446 Such documents should clearly identify the registry into which each 447 value is to be registered. Use the exact registry name as listed on 448 the IANA web page, and cite the RFC where the registry is defined. 450 There is no need to mention what the assignment policy is when making 451 new assignments in existing registries, as that should be clear from 452 the references. However, if multiple assignment policies might 453 apply, as in registries with different ranges that have different 454 policies, it is important to make it clear which range is being 455 requested, so that IANA will know which policy applies and can assign 456 a value in the correct range. 458 When referring to an existing registry, providing a URL to precisely 459 identify the registry is helpful. See Section 2.2 for details on 460 specifying the correct URL. 462 For example, a document could contain something like this: 464 This registration should be made in the Foobar Operational 465 Parameters registry, located at . 468 Normally, numeric values to be used are chosen by IANA when the 469 document is approved, and drafts should not specify final values. 470 Instead, placeholders such as "TBD1" and "TBD2" should be used 471 consistently throughout the document, giving each item to be 472 registered a different placeholder. The IANA Considerations should 473 ask the RFC Editor to replace the placeholder names with the IANA- 474 assigned values. When drafts need to specify numeric values for 475 testing or early implementations, they will either request early 476 allocation (see Section 3.4) or use values that have already been set 477 aside for testing or experimentation (if the registry in question 478 allows that without explicit assignment). It is important that 479 drafts not choose their own values, lest IANA assign one of those 480 values to another document in the meantime. A draft can request a 481 specific value in the IANA Considerations section, and IANA will 482 accommodate such requests when that's possible, but the proposed 483 number might have been assigned to some other use by the time the 484 draft is approved. 486 Normally, text-string values to be used are specified in the 487 document, as collisions are less likely with text strings. IANA will 488 consult with the authors if there is, in fact, a collision, and a 489 different value has to be used. When drafts need to specify string 490 values for testing or early implementations, they sometimes use the 491 expected final value. But it is often useful to use a draft value 492 instead, possibly including the draft version number. This allows 493 the early implementations to be distinguished from those implementing 494 the final version. A document that intends to use "foobar" in the 495 final version might use "foobar-testing-draft-05" for the -05 version 496 of the draft, for example. 498 For some registries, IANA has a long-standing policy prohibiting 499 assignment of names or codes on a vanity or organization-name basis. 500 For example, codes might always be assigned sequentially unless there 501 is a strong reason for making an exception. Nothing in this document 502 is intended to change those policies or prevent their future 503 application. 505 As an example, the following text could be used to request assignment 506 of a DHCPv6 option number: 508 IANA is asked to assign an option code value of TBD1 to the DNS 509 Recursive Name Server option and an option code value of TBD2 to 510 the Domain Search List option from the DHCP option code space 511 defined in Section 24.3 of RFC 3315. 513 The IANA Considerations section should summarize all of the IANA 514 actions, with pointers to the relevant sections elsewhere in the 515 document as appropriate. Including section numbers is especially 516 useful when the reference document is large; the section numbers will 517 make it easier for those searching the reference document to find the 518 relevant information. 520 When multiple values are requested, it is generally helpful to 521 include a summary table of the additions/changes. It is also helpful 522 for this table to be in the same format as it appears or will appear 523 on the IANA web site. For example: 525 Value Description Reference 526 -------- ------------------- --------- 527 TBD1 Foobar this RFC, Section 3.2 528 TBD2 Gumbo this RFC, Section 3.3 529 TBD3 Banana this RFC, Section 3.4 531 Note: In cases where authors feel that including the full table of 532 changes is too verbose or repetitive, authors should still include 533 the table in the draft, but may include a note asking that the table 534 be removed prior to publication of the final RFC. 536 3.2. Updating Existing Registrations 538 Even after a number has been assigned, some types of registrations 539 contain additional information that may need to be updated over time. 541 For example, MIME media types, character sets, and language tags 542 typically include more information than just the registered value 543 itself, and may need updates to items such as point-of-contact 544 information, security issues, pointers to updates, and literature 545 references. 547 In such cases, the document defining the namespace must clearly state 548 who is responsible for maintaining and updating a registration. 549 Depending on the registry, it may be appropriate to specify one or 550 more of: 552 o Letting registrants and/or nominated change controllers update 553 their own registrations, subject to the same constraints and 554 review as with new registrations. 556 o Allowing attachment of comments to the registration. This can be 557 useful in cases where others have significant objections to a 558 registration, but the author does not agree to change the 559 registration. 561 o Designating the IESG, a designated expert, or another entity as 562 having the right to change the registrant associated with a 563 registration and any requirements or conditions on doing so. This 564 is mainly to get around the problem when a registrant cannot be 565 reached in order to make necessary updates. 567 3.3. Overriding Registration Procedures 569 Experience has shown that the documented IANA considerations for 570 individual protocols do not always adequately cover the reality of 571 registry operation, or are not sufficiently clear. In addition, 572 documented IANA considerations are sometimes found to be too 573 stringent to allow even working group documents (for which there is 574 strong consensus) to perform a registration in advance of actual RFC 575 publication. 577 In order to allow assignments in such cases, the IESG is granted 578 authority to override registration procedures and approve assignments 579 on a case-by-case basis. 581 The intention here is not to overrule properly documented procedures, 582 or to obviate the need for protocols to properly document their IANA 583 considerations. Rather, it is to permit assignments in specific 584 cases where it is obvious that the assignment should just be made, 585 but updating the IANA process beforehand is too onerous. 587 When the IESG is required to take action as described above, it is a 588 strong indicator that the applicable registration procedures should 589 be updated, possibly in parallel with the work that instigated it. 591 IANA always has the discretion to ask the IESG for advice or 592 intervention when they feel it is needed, such as in cases where 593 policies or procedures are unclear to them, where they encounter 594 issues or questions they are unable to resolve, or where registration 595 requests or patterns of requests appear to be unusual or abusive. 597 3.4. Early Allocations 598 IANA normally takes its actions when a document is approved for 599 publication. There are times, though, when early allocation of a 600 value is important for the development of a technology: for example, 601 when early implementations are created while the document is still 602 under development. 604 IANA has a mechanism for handling such early allocations in some 605 cases. See [RFC7120] for details. It is usually not necessary to 606 explicitly mark a registry as allowing early allocation, because the 607 general rules will apply. 609 4. Choosing a Registration Policy, and Well-Known Policies 611 A registration policy is the policy that controls how new assignments 612 in a registry are accepted. There are several issues to consider 613 when defining the registration policy. 615 If the registry's namespace is limited, assignments will need to be 616 made carefully to prevent exhaustion. 618 Even when the space is essentially unlimited, it is still often 619 desirable to have at least a minimal review prior to assignment in 620 order to: 622 o prevent the hoarding of or unnecessary wasting of values. For 623 example, if the space consists of text strings, it may be 624 desirable to prevent entities from obtaining large sets of strings 625 that correspond to desirable names (existing company names, for 626 example). 628 o provide a sanity check that the request actually makes sense and 629 is necessary. Experience has shown that some level of minimal 630 review from a subject matter expert is useful to prevent 631 assignments in cases where the request is malformed or not 632 actually needed (for example, an existing assignment for an 633 essentially equivalent service already exists). 635 Perhaps most importantly, unreviewed extensions can impact 636 interoperability and security. See [RFC6709]. 638 When the namespace is essentially unlimited and there are no 639 potential interoperability or security issues, assigned numbers can 640 usually be given out to anyone without any subjective review. In 641 such cases, IANA can make assignments directly, provided that IANA is 642 given detailed instructions on what types of requests it should 643 grant, and it is able to do so without exercising subjective 644 judgement. 646 When this is not the case, some level of review is required. 647 However, it's important to balance adequate review and ease of 648 registration. In many cases, those making registrations will not be 649 IETF participants; requests often come from other standards 650 organizations, from organizations not directly involved in standards, 651 from ad-hoc community work (from an open-source project, for 652 example), and so on. Registration must not be unnecessarily 653 difficult, unnecessarily costly (in terms of time and other 654 resources), nor unnecessarily subject to denial. 656 While it is sometimes necessary to restrict what gets registered 657 (e.g., for limited resources such as bits in a byte, or for items for 658 which unsupported values can be damaging to protocol operation), in 659 many cases having what's in use represented in the registry is more 660 important. Overly strict review criteria and excessive cost (in time 661 and effort) discourage people from even attempting to make a 662 registration. If a registry fails to reflect the protocol elements 663 actually in use, it can adversely affect deployment of protocols on 664 the Internet, and the registry itself is devalued. 666 Therefore, working groups and other document developers should use 667 care in selecting appropriate registration policies when their 668 documents create registries. They should select the least strict 669 policy that suits a registry's needs, and look for specific 670 justification for policies that require significant community 671 involvement (those stricter than Expert Review or Specification 672 Required, in terms of the well-known policies). 674 The following policies are defined for common usage. These cover a 675 range of typical policies that have been used to describe the 676 procedures for assigning new values in a namespace. It is not 677 strictly required that documents use these terms; the actual 678 requirement is that the instructions to IANA be clear and 679 unambiguous. However, use of these terms is strongly recommended 680 because their meanings are widely understood, and newly minted 681 policies should not be used without good reason and explanation. The 682 terms are fully explained in the following subsections. 684 1. Private Use 685 2. Experimental Use 686 3. Hierarchical Allocation 687 4. First Come First Served 688 5. Expert Review 689 6. Specification Required 690 7. RFC Required 691 8. IETF Review 692 9. Standards Action 693 10. IESG Approval 695 It should be noted that it often makes sense to partition a namespace 696 into multiple categories, with assignments within each category 697 handled differently. Many protocols now partition namespaces into 698 two or more parts, with one range reserved for Private or 699 Experimental Use while other ranges are reserved for globally unique 700 assignments assigned following some review process. Dividing a 701 namespace into ranges makes it possible to have different policies in 702 place for different ranges and different use cases. 704 Similarly, it will often be useful to specify multiple policies in 705 parallel, with each policy being used under different circumstances. 706 For more discussion of that topic, see Section 4.12. 708 Examples of RFCs that specify multiple policies in parallel: 710 LDAP [RFC4520] 711 TLS ClientCertificateType Identifiers [RFC5246] (as detailed in 712 the subsections below) 713 MPLS Pseudowire Types Registry [RFC4446] 715 4.1. Private Use 717 For private or local use only, with the type and purpose defined by 718 the local site. No attempt is made to prevent multiple sites from 719 using the same value in different (and incompatible) ways. IANA does 720 not record assignments from registries or ranges with this policy 721 (and therefore there is no need for IANA to review them) and 722 assignments are not generally useful for broad interoperability. It 723 is the responsibility of the sites making use of the Private Use 724 range to ensure that no conflicts occur (within the intended scope of 725 use). 727 Examples: 729 Site-specific options in DHCP [RFC2939] 730 Fibre Channel Port Type Registry [RFC4044] 731 TLS ClientCertificateType Identifiers 224-255 [RFC5246] 733 4.2. Experimental Use 735 Experimental Use is similar to Private Use, but with the purpose 736 being to facilitate experimentation. See [RFC3692] for details. 737 IANA does not record assignments from registries or ranges with this 738 policy (and therefore there is no need for IANA to review them) and 739 assignments are not generally useful for broad interoperability. 740 Unless the registry explicitly allows it, it is not appropriate for 741 documents to select explicit values from registries or ranges with 742 this policy. Specific experiments will select a value to use during 743 the experiment. 745 When code points are set aside for experimental use, it's important 746 to make clear any expected restrictions on experimental scope. For 747 example, say whether it's acceptable to run experiments using those 748 code points over the open Internet, or whether such experiments 749 should be confined to more closed environments. See [RFC6994] for an 750 example of such considerations. 752 Example: 754 Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP 755 Headers [RFC4727] 757 4.3. Hierarchical Allocation 759 With Hierarchical Allocation, delegated administrators are given 760 control over part of the namespace, and can assign values in that 761 part of the namespace. IANA makes allocations in the higher levels 762 of the namespace according to one of the other policies. 764 Examples: 766 - DNS names. IANA manages the top-level domains (TLDs), and, as 767 [RFC1591] says: 769 Under each TLD may be created a hierarchy of names. Generally, 770 under the generic TLDs the structure is very flat. That is, 771 many organizations are registered directly under the TLD, and 772 any further structure is up to the individual organizations. 774 - Object Identifiers, defined by ITU-T recommendation X.208. 775 According to , some registries 776 include 778 * IANA, which hands out OIDs the "Private Enterprises" branch, 779 * ANSI, which hands out OIDs under the "US Organizations" branch, 780 and 781 * BSI, which hands out OIDs under the "UK Organizations" branch. 783 - URN namespaces. IANA registers URN Namespace IDs (NIDs [RFC3406]), 784 and the organization registering an NID is responsible for 785 allocations of URNs within that namespace. 787 4.4. First Come First Served 788 For the First Come First Served policy, assignments are made to 789 anyone on a first come, first served basis. There is no substantive 790 review of the request, other than to ensure that it is well-formed 791 and doesn't duplicate an existing assignment. However, requests must 792 include a minimal amount of clerical information, such as a point of 793 contact (including an email address, and sometimes a postal address) 794 and a brief description of how the value will be used. Additional 795 information specific to the type of value requested may also need to 796 be provided, as defined by the namespace. For numbers, IANA 797 generally assigns the next in-sequence unallocated value, but other 798 values may be requested and assigned if an extenuating circumstance 799 exists. With names, specific text strings can usually be requested. 801 When creating a new registry with First Come First Served as the 802 registration policy, in addition to the contact person field or 803 reference, the registry should contain a field for change controller. 804 Having a change controller for each entry for these types of 805 registrations makes authorization of future modifications more clear. 806 See Section 2.3. 808 It is important that changes to the registration of a First Come 809 First Served code point retain compatibility with the current usage 810 of that code point, and so changes need to be made with care. The 811 change controller should not, in most cases, be requesting 812 incompatible changes nor repurposing a registered code point. See 813 also Section 9.4 and Section 9.5. 815 A working group or any other entity that is developing a protocol 816 based on a First Come First Served code point has to be extremely 817 careful that the protocol retains wire compatibility with current use 818 of the code point. Once that is no longer true, the new work needs 819 to change to a different code point (and register that use at the 820 appropriate time). 822 It is also important to understand that First Come First Served 823 really has no filtering. Essentially, any well formed request is 824 accepted. 826 Examples: 828 SASL mechanism names [RFC4422] 829 LDAP Protocol Mechanisms and LDAP Syntax [RFC4520] 831 4.5. Expert Review 833 (Also called "Designated Expert" in earlier editions of this 834 document.) For the Expert Review policy, review and approval by a 835 designated expert (see Section 5) is required. 837 The required documentation and review criteria, giving clear guidance 838 to the designated expert, should be provided when defining the 839 registry. It is particularly important to lay out what should be 840 considered when performing an evaluation and reasons for rejecting a 841 request. It is also a good idea to include, when possible, a sense 842 of whether many registrations are expected over time, or if the 843 registry is expected to be updated infrequently or in exceptional 844 circumstances only. 846 Good examples of guidance to designated experts: 848 Extensible Authentication Protocol (EAP) [RFC3748], Sections 6 and 849 7.2 850 North-Bound Distribution of Link-State and TE Information using 851 BGP [RFC7752], Section 5.1 853 When creating a new registry with Expert Review as the registration 854 policy, in addition to the contact person field or reference, the 855 registry should contain a field for change controller. Having a 856 change controller for each entry for these types of registrations 857 makes authorization of future modifications more clear. See Section 858 2.3 860 Examples: 862 EAP Method Types [RFC3748] 863 HTTP Digest AKA algorithm versions [RFC4169] 864 URI schemes [RFC4395] 865 GEOPRIV Location Types [RFC4589] 867 4.6. Specification Required 869 For the Specification Required policy, review and approval by a 870 designated expert (see Section 5) is required, and the values and 871 their meanings must be documented in a permanent and readily 872 available public specification, in sufficient detail so that 873 interoperability between independent implementations is possible. 874 The designated expert will review the public specification and 875 evaluate whether it is sufficiently stable and permanent, and 876 sufficiently clear to allow interoperable implementations. 878 The intention behind "permanent and readily available" is that a 879 document can reasonably be expected to be findable and retrievable 880 long after IANA assignment of the requested value. Publication of an 881 RFC is an ideal means of achieving this requirement, but 882 Specification Required is intended to also cover the case of a 883 document published outside of the RFC path, including informal 884 documentation. 886 For RFC publication, formal review by the designated expert is still 887 requested, but the normal RFC review process is expected to provide 888 the necessary review for interoperability. The designated expert's 889 review is still important, but it's equally important to note that 890 when there is IETF consensus, the expert can sometimes be "in the 891 rough" (see also the last paragraph of Section 5.4). 893 As with Expert Review (Section 4.5), clear guidance to the designated 894 expert, should be provided when defining the registry. 896 When specifying this policy, just use the term "Specification 897 Required". Some specifications have chosen to refer to it as "Expert 898 Review with Specification Required", and that only causes confusion. 900 Examples: 902 Diffserv-aware TE Bandwidth Constraints Model Identifiers 903 [RFC4124] 904 TLS ClientCertificateType Identifiers 64-223 [RFC5246] 905 ROHC Profile Identifiers [RFC5795] 907 4.7. RFC Required 909 With the RFC Required policy, the registration request, along with 910 associated documentation, must be published in an RFC. The RFC need 911 not be in the IETF stream, but may be in any RFC stream (currently an 912 RFC may be in the IETF, IRTF, or IAB stream, or an RFC Editor 913 Independent Submission [RFC5742]). 915 Unless otherwise specified, any type of RFC is sufficient (currently 916 Standards Track, BCP, Informational, Experimental, or Historic). 918 4.8. IETF Review 920 (Formerly called "IETF Consensus" in the first edition of this 921 document.) With the IETF Review policy, new values are assigned only 922 through RFCs in the IETF Stream -- those that have been shepherded 923 through the IESG as AD-Sponsored or IETF working group Documents 924 [RFC2026] [RFC5378], have gone through IETF last call, and that the 925 IESG has approved as having IETF consensus. 927 The intent is that the document and proposed assignment will be 928 reviewed by the IETF community (including appropriate IETF working 929 groups, directorates, and other experts) and by the IESG, to ensure 930 that the proposed assignment will not negatively affect 931 interoperability or otherwise extend IETF protocols in an 932 inappropriate or damaging manner. To ensure adequate community 933 review, such documents will always undergo an IETF Last Call. 935 Unless otherwise specified, any type of RFC is sufficient (currently 936 Standards Track, BCP, Informational, Experimental, or Historic). 938 Examples: 940 IPSECKEY Algorithm Types [RFC4025] 941 Accounting-Auth-Method AVP values in DIAMETER [RFC4005] 942 TLS Extension Types [RFC5246] 944 4.9. Standards Action 946 For the Standards Action policy, values are assigned only through 947 Standards Track or Best Current Practice RFCs in the IETF Stream. 949 Examples: 951 BGP message types [RFC4271] 952 Mobile Node Identifier option types [RFC4283] 953 TLS ClientCertificateType Identifiers 0-63 [RFC5246] 954 DCCP Packet Types [RFC4340] 956 4.10. IESG Approval 958 New assignments may be approved by the IESG. Although there is no 959 requirement that the request be documented in an RFC, the IESG has 960 discretion to request documents or other supporting materials on a 961 case-by-case basis. 963 IESG Approval is not intended to be used often or as a "common case"; 964 indeed, it has seldom been used in practice. Rather, it is intended 965 to be available in conjunction with other policies as a fall-back 966 mechanism in the case where one of the other allowable approval 967 mechanisms cannot be employed in a timely fashion or for some other 968 compelling reason. IESG Approval is not intended to circumvent the 969 public review processes implied by other policies that could have 970 been employed for a particular assignment. IESG Approval would be 971 appropriate, however, in cases where expediency is desired and there 972 is strong consensus (such as from a working group) for making the 973 assignment. 975 Before approving a request, the IESG might consider consulting the 976 community, via a "call for comments" that provides as much 977 information as is reasonably possible about the request. 979 Examples: 981 IPv4 Multicast address assignments [RFC5771] 982 IPv4 IGMP Type and Code values [RFC3228] 983 Mobile IPv6 Mobility Header Type and Option values [RFC6275] 985 4.11. Using the Well-Known Registration Policies 987 Because the well-known policies benefit from both community 988 experience and wide understanding, their use is encouraged, and the 989 making up of new policies needs to be accompanied by reasonable 990 justification. 992 It is also acceptable to cite one of the well-known policies and 993 include additional guidelines for what kind of considerations should 994 be taken into account by the review process. 996 For example, RADIUS [RFC3575] specifies the use of a Designated 997 Expert, but includes specific additional criteria the Designated 998 Expert should follow. 1000 The well-known policies from "First Come First Served" to "Standards 1001 Action" specify a range of policies in increasing order of strictness 1002 (using the numbering from the full list in Section 4): 1004 4. First Come First Served 1005 No review, minimal documentation. 1007 5/6. Expert Review / Specification Required 1008 Expert review with sufficient documentation for review. / 1009 Significant stable public documentation sufficient for 1010 interoperability. 1012 7. RFC Required 1013 Any RFC publication, IETF or a non-IETF Stream. 1015 8. IETF Review 1016 RFC publication, IETF Stream only, but need not be Standards 1017 Track. 1019 9. Standards Action 1020 RFC publication, IETF Stream, Standards Track or BCP only. 1022 Examples of situations that might merit IETF Review or Standards 1023 Action include the following: 1025 o When a resource is limited, such as bits in a byte (or in two 1026 bytes, or four), or numbers in a limited range. In these cases, 1027 allowing registrations that haven't been carefully reviewed and 1028 agreed by community consensus could too quickly deplete the 1029 allowable values. 1031 o When thorough community review is necessary to avoid extending or 1032 modifying the protocol in ways that could be damaging. One 1033 example is in defining new command codes, as opposed to options 1034 that use existing command codes: the former might require a strict 1035 policy, where a more relaxed policy could be adequate for the 1036 latter. Another example is in defining protocol elements that 1037 change the semantics of existing operations. 1039 o When there are security implications with respect to the resource, 1040 and thorough review is needed to ensure that the new usage is 1041 sound. Examples of this include lists of acceptable hashing and 1042 cryptographic algorithms, and assignment of transport ports in the 1043 system range. 1045 When reviewing a document that asks IANA to create a new registry or 1046 change a registration policy to any policy more stringent than Expert 1047 Review or Specification Required, the IESG should ask for 1048 justification to ensure that more relaxed policies have been 1049 considered and that the strict policy is the right one. 1051 Accordingly, document developers need to anticipate this and document 1052 their considerations for selecting the specified policy (ideally, in 1053 the document itself; failing that, in the shepherd writeup). 1054 Likewise, the document shepherd should ensure that the selected 1055 policies have been justified before sending the document to the IESG. 1057 When specifications are revised, registration policies should be 1058 reviewed in light of experience since the policies were set. 1060 4.12. Using Multiple Policies in Combination 1062 In some situations, it is necessary to define multiple registration 1063 policies. For example, registrations through the normal IETF process 1064 might use one policy, while registrations from outside the process 1065 would have a different policy applied. 1067 Thus, a particular registry might want to use a policy such as "RFC 1068 Required" or "IETF Review" sometimes, with a designated expert 1069 checking a "Specification Required" policy at other times. 1071 The alternative to using a combination requires either that all 1072 requests come through RFCs or that requests in RFCs go through review 1073 by the designated expert, even though they already have IETF review 1074 and consensus. 1076 This can be documented in the IANA Considerations section when the 1077 registry is created: 1079 IANA is asked to create the registry "Fruit Access Flags" under 1080 the "Fruit Parameters" group. New registrations will be permitted 1081 through either the IETF Review policy or the Specification 1082 Required policy [BCP26]. The latter should be used only for 1083 registrations requested by SDOs outside the IETF. Registrations 1084 requested in IETF documents will be subject to IETF review. 1086 Such combinations will commonly use one of {Standards Action, IETF 1087 Review, RFC Required} in combination with one of {Specification 1088 Required, Expert Review}. Guidance should be provided about when 1089 each policy is appropriate, as in the example above. 1091 5. Designated Experts 1093 5.1. The Motivation for Designated Experts 1095 Discussion on a mailing list can provide valuable technical feedback, 1096 but opinions often vary and discussions may continue for some time 1097 without clear resolution. In addition, IANA cannot participate in 1098 all of these mailing lists and cannot determine if or when such 1099 discussions reach consensus. Therefore, IANA relies on a "designated 1100 expert" for advice regarding the specific question of whether an 1101 assignment should be made. The designated expert is an individual 1102 who is responsible for carrying out an appropriate evaluation and 1103 returning a recommendation to IANA. 1105 It should be noted that a key motivation for having designated 1106 experts is for the IETF to provide IANA with a subject matter expert 1107 to whom the evaluation process can be delegated. IANA forwards 1108 requests for an assignment to the expert for evaluation, and the 1109 expert (after performing the evaluation) informs IANA as to whether 1110 or not to make the assignment or registration. In most cases, the 1111 registrants do not work directly with the designated experts. The 1112 list of designated experts for a registry is listed in the registry. 1114 It will often be useful to use a designated expert only some of the 1115 time, as a supplement to other processes. For more discussion of 1116 that topic, see Section 4.12. 1118 5.2. The Role of the Designated Expert 1120 The designated expert is responsible for coordinating the appropriate 1121 review of an assignment request. The review may be wide or narrow, 1122 depending on the situation and the judgment of the designated expert. 1123 This may involve consultation with a set of technology experts, 1124 discussion on a public mailing list, consultation with a working 1125 group (or its mailing list if the working group has disbanded), etc. 1126 Ideally, the designated expert follows specific review criteria as 1127 documented with the protocol that creates or uses the namespace. See 1128 the IANA Considerations sections of [RFC3748] and [RFC3575] for 1129 specific examples. 1131 Designated experts are expected to be able to defend their decisions 1132 to the IETF community, and the evaluation process is not intended to 1133 be secretive or bestow unquestioned power on the expert. Experts are 1134 expected to apply applicable documented review or vetting procedures, 1135 or in the absence of documented criteria, follow generally accepted 1136 norms such as those in Section 5.3. 1138 It has proven useful to have multiple designated experts for some 1139 registries. Sometimes those experts work together in evaluating a 1140 request, while in other cases additional experts serve as backups, 1141 acting only when the primary expert is unavailable. In registries 1142 with a pool of experts, the pool often has a single chair responsible 1143 for defining how requests are to be assigned to and reviewed by 1144 experts. In other cases, IANA might assign requests to individual 1145 members in sequential or approximate random order. 1147 In cases of disagreement among multiple experts, it is the 1148 responsibility of those experts to make a single clear recommendation 1149 to IANA. It is not appropriate for IANA to resolve disputes among 1150 experts. In extreme situations, such as deadlock, the designating 1151 body may need to step in to resolve the problem. 1153 If a designated expert is conflicted for a particular review (is, for 1154 example, an author or significant proponent of a specification 1155 related to the registration under review), that expert should recuse 1156 himself. In the event that all the designated experts are 1157 conflicted, they should ask that a temporary expert be designated for 1158 the conflicted review. 1160 This document defines the designated expert mechanism with respect to 1161 documents in the IETF stream only. Documents in other streams may 1162 use a registration policy that requires a designated expert only if 1163 those streams (or those documents) specify how designated experts are 1164 appointed and managed. What is described below, with management by 1165 the IESG, is only appropriate for the IETF stream. 1167 5.2.1. Managing Designated Experts in the IETF 1169 Designated experts for registries created by the IETF are appointed 1170 by the IESG, normally upon recommendation by the relevant Area 1171 Director. They may be appointed at the time a document creating or 1172 updating a namespace is approved by the IESG, or subsequently, when 1173 the first registration request is received. Because experts 1174 originally appointed may later become unavailable, the IESG will 1175 appoint replacements as necessary. The IESG may remove any 1176 designated expert that it appointed, at its discretion. 1178 The normal appeals process, as described in [RFC2026], Section 6.5.1, 1179 applies to issues that arise with the designated expert team. For 1180 this purpose, the designated expert team takes the place of the 1181 working group in that description. 1183 5.3. Designated Expert Reviews 1185 In the years since RFC 2434 was published and has been put to use, 1186 experience has led to the following observations: 1188 o A designated expert must respond in a timely fashion, normally 1189 within a week for simple requests to a few weeks for more complex 1190 ones. Unreasonable delays can cause significant problems for 1191 those needing assignments, such as when products need code points 1192 to ship. This is not to say that all reviews can be completed 1193 under a firm deadline, but they must be started, and the requester 1194 and IANA should have some transparency into the process if an 1195 answer cannot be given quickly. 1197 o If a designated expert does not respond to IANA's requests within 1198 a reasonable period of time, either with a response or with a 1199 reasonable explanation for the delay (some requests may be 1200 particularly complex), and if this is a recurring event, IANA must 1201 raise the issue with the IESG. Because of the problems caused by 1202 delayed evaluations and assignments, the IESG should take 1203 appropriate actions to ensure that the expert understands and 1204 accepts his or her responsibilities, or appoint a new expert. 1206 o The designated expert is not required to personally bear the 1207 burden of evaluating and deciding all requests, but acts as a 1208 shepherd for the request, enlisting the help of others as 1209 appropriate. In the case that a request is denied, and rejecting 1210 the request is likely to be controversial, the expert should have 1211 the support of other subject matter experts. That is, the expert 1212 must be able to defend a decision to the community as a whole. 1214 When a designated expert is used, the documentation should give clear 1215 guidance to the designated expert, laying out criteria for performing 1216 an evaluation and reasons for rejecting a request. In the case where 1217 there are no specific documented criteria, the presumption should be 1218 that a code point should be granted unless there is a compelling 1219 reason to the contrary. Reasons that have been used to deny requests 1220 have included these: 1222 o Scarcity of code points, where the finite remaining code points 1223 should be prudently managed, or where a request for a large number 1224 of code points is made and a single code point is the norm. 1226 o Documentation is not of sufficient clarity to evaluate or ensure 1227 interoperability. 1229 o The code point is needed for a protocol extension, but the 1230 extension is not consistent with the documented (or generally 1231 understood) architecture of the base protocol being extended, and 1232 would be harmful to the protocol if widely deployed. It is not 1233 the intent that "inconsistencies" refer to minor differences "of a 1234 personal preference nature". Instead, they refer to significant 1235 differences such as inconsistencies with the underlying security 1236 model, implying a change to the semantics of an existing message 1237 type or operation, requiring unwarranted changes in deployed 1238 systems (compared with alternate ways of achieving a similar 1239 result), etc. 1241 o The extension would cause problems with existing deployed systems. 1243 o The extension would conflict with one under active development by 1244 the IETF, and having both would harm rather than foster 1245 interoperability. 1247 When a designated expert is used, documents must not name the 1248 designated expert in the document itself; instead, any suggested 1249 names should be relayed to the appropriate Area Director at the time 1250 the document is sent to the IESG for approval. This is usually done 1251 in the document shepherd writeup. 1253 If the request should also be reviewed on a specific public mailing 1254 list, its address should be specified. 1256 5.4. Expert Reviews and the Document Lifecycle 1258 Review by the designated expert is necessarily done at a particular 1259 point in time, and represents review of a particular version of the 1260 document. While reviews are generally done around the time of IETF 1261 last call, deciding when the review should take place is a question 1262 of good judgment. And while re-reviews might be done when it's 1263 acknowledged that the documentation of the registered item has 1264 changed substantially, making sure that re-review happens requires 1265 attention and care. 1267 It is possible, through carelessness, accident, inattentiveness, or 1268 even willful disregard, that changes might be made after the 1269 designated expert's review and approval that would, if the document 1270 were re-reviewed, cause the expert not to approve the registration. 1271 It is up to the IESG, with the token held by the responsible Area 1272 Director, to be alert to such situations and to recognize that such 1273 changes need to be checked. 1275 For registrations made from documents on the Standards Track, there 1276 is often expert review required (by the registration policy) in 1277 addition to IETF consensus (for approval as a Standards Track RFC). 1278 In such cases, the review by the designated expert needs to be 1279 timely, submitted before the IESG evaluates the document. The IESG 1280 should generally not hold the document up waiting for late review. 1281 It is also not intended for the expert review to override IETF 1282 consensus: the IESG should consider the review in its own evaluation, 1283 as it would do for other last-call reviews. 1285 6. Well-Known Registration Status Terminology 1287 The following labels describe the status of an assignment or range of 1288 assignments: 1290 Private Use: Private use only (not assigned), as described in 1291 Section 4.1. 1293 Experimental: Available for general experimental use as described 1294 in [RFC3692]. IANA does not record specific assignments for 1295 any particular use. 1297 Unassigned: Not currently assigned, and available for assignment 1298 via documented procedures. While it's generally clear that 1299 any values that are not registered are unassigned and 1300 available for assignment, it is sometimes useful to 1301 explicitly specify that situation. Note that this is 1302 distinctly different from "Reserved". 1304 Reserved: Not assigned and not available for assignment. Reserved 1305 values are held for special uses, such as to extend the 1306 namespace when it becomes exhausted. "Reserved" is also 1307 sometimes used to designate values that had been assigned 1308 but are no longer in use, keeping them set aside as long as 1309 other unassigned values are available. Note that this is 1310 distinctly different from "Unassigned". 1312 Reserved values can be released for assignment by the change 1313 controller for the registry (this is often the IESG, for 1314 registries created by RFCs in the IETF stream). 1316 Known Unregistered Use: It's known that the assignment or range is 1317 in use without having been defined in accordance with 1318 reasonable practice. Documentation for use of the 1319 assignment or range may be unavailable, inadequate, or 1320 conflicting. This is a warning against use, as well as an 1321 alert to network operators, who might see these values in 1322 use on their networks. 1324 7. Documentation References in IANA Registries 1325 Usually, registries and registry entries include references to 1326 documentation (RFCs or other documents). The purpose of these 1327 references is to provide pointers for implementors to find details 1328 necessary for implementation, NOT to simply note what document 1329 created the registry or entry. Therefore: 1331 o If a document registers an item that is defined and explained 1332 elsewhere, the registered reference should be to the document 1333 containing the definition, not to the document that is merely 1334 performing the registration. 1336 o If the registered item is defined and explained in the current 1337 document, it is important to include sufficient information to 1338 enable implementors to understand the item and to create a proper 1339 implementation. 1341 o If the registered item is explained primarily in a specific 1342 section of the reference document, it is useful to include a 1343 section reference. For example, "[RFC4637], Section 3.2", rather 1344 than just "[RFC4637]". 1346 o For documentation of a new registry, the reference should provide 1347 information about the registry itself, not just a pointer to the 1348 creation of it. Useful information includes the purpose of the 1349 registry, a rationale for its creation, documentation of the 1350 process and policy for new registrations, guidelines for new 1351 registrants or designated experts, and other such related 1352 information. But note that, while it's important to include this 1353 information in the document, it needn't all be in the IANA 1354 Considerations section. See Section 1.1. 1356 8. What to Do in "bis" Documents 1358 On occasion, an RFC is issued that obsoletes a previous edition of 1359 the same document. We sometimes call these "bis" documents, such as 1360 when RFC 4637 is obsoleted by draft-ietf-foo-rfc4637bis. When the 1361 original document created registries and/or registered entries, there 1362 is a question of how to handle the IANA Considerations section in the 1363 "bis" document. 1365 If the registrations specify the original document as a reference, 1366 those registrations should be updated to point to the current (not 1367 obsolete) documentation for those items. Usually, that will mean 1368 changing the reference to be the "bis" document. 1370 There will, though, be times when a document updates another, but 1371 does not make it obsolete, and the definitive reference is changed 1372 for some items but not for others. Be sure that the references are 1373 always set to point to the correct, current documentation for each 1374 item. 1376 For example, suppose RFC 4637 registered the "BANANA" flag in the 1377 "Fruit Access Flags" registry, and the documentation for that flag is 1378 in Section 3.2. 1380 The current registry might look, in part, like this: 1382 Name Description Reference 1383 -------- ------------------- --------- 1384 BANANA Flag for bananas [RFC4637], Section 3.2 1386 If draft-ietf-foo-rfc4637bis obsoletes RFC 4637 and, because of some 1387 rearrangement, now documents the flag in Section 4.1.2, the IANA 1388 Considerations of the bis document might contain text such as this: 1390 IANA is asked to change the registration information for the 1391 BANANA flag in the "Fruit Access Flags" registry to the following: 1393 Name Description Reference 1394 -------- ------------------- --------- 1395 BANANA Flag for bananas [[this RFC]], Section 4.2.1 1397 In many cases, if there are a number of registered references to the 1398 original RFC and the document organization has not changed the 1399 registered section numbering much, it may simply be reasonable to do 1400 this: 1402 Because this document obsoletes RFC 4637, IANA is asked to change 1403 all registration information that references [RFC4637] to instead 1404 reference [[this RFC]]. 1406 If information for registered items has been or is being moved to 1407 other documents, then, of course, the registration information should 1408 be changed to point to those other documents. In no case is it 1409 reasonable to leave documentation pointers to the obsoleted document 1410 for any registries or registered items that are still in current use. 1412 It is extremely important to be clear in your instructions regarding 1413 updating references, especially in cases where some references need 1414 to be updated and others do not. 1416 9. Miscellaneous Issues 1418 9.1. When There Are No IANA Actions 1420 Before an Internet-Draft can be published as an RFC, IANA needs to 1421 know what actions (if any) it needs to perform. Experience has shown 1422 that it is not always immediately obvious whether a document has no 1423 IANA actions, without reviewing the document in some detail. In 1424 order to make it clear to IANA that it has no actions to perform (and 1425 that the author has consciously made such a determination), such 1426 documents should, after the authors confirm that this is the case, 1427 include an IANA Considerations section that states: 1429 This document has no IANA actions. 1431 IANA prefers that these "empty" IANA Considerations sections be left 1432 in the document for the record: it makes it clear later on that the 1433 document explicitly said that no IANA actions were needed (and that 1434 it wasn't just omitted). This is a change from the prior practice of 1435 requesting that such sections be removed by the RFC Editor, and 1436 authors are asked to accommodate this change. 1438 9.2. Namespaces Lacking Documented Guidance 1440 For all existing RFCs that either explicitly or implicitly rely on 1441 IANA to make assignments without specifying a precise assignment 1442 policy, IANA (in consultation with the IESG) will continue to decide 1443 what policy is appropriate. Changes to existing policies can always 1444 be initiated through the normal IETF consensus process, or through 1445 the IESG when appropriate. 1447 All future RFCs that either explicitly or implicitly rely on IANA to 1448 register or otherwise administer namespace assignments must provide 1449 guidelines for administration of the namespace. 1451 9.3. After-the-Fact Registrations 1453 Occasionally, the IETF becomes aware that an unassigned value from a 1454 namespace is in use on the Internet or that an assigned value is 1455 being used for a different purpose than it was registered for. The 1456 IETF does not condone such misuse; procedures of the type described 1457 in this document need to be applied to such cases, and it might not 1458 always be possible to formally assign the desired value. In the 1459 absence of specifications to the contrary, values may only be 1460 reassigned for a different purpose with the consent of the original 1461 assignee (when possible) and with due consideration of the impact of 1462 such a reassignment. In cases of likely controversy, consultation 1463 with the IESG is advised. 1465 This is part of the reason for the advice in Section 3.1 about using 1466 placeholder values, such as "TBD1", during document development: open 1467 use of unregistered values after results from well-meant, early 1468 implementations, where the implementations retained the use of 1469 developmental code points that never proceeded to a final IANA 1470 assignment. 1472 9.4. Reclaiming Assigned Values 1473 Reclaiming previously assigned values for reuse is tricky, because 1474 doing so can lead to interoperability problems with deployed systems 1475 still using the assigned values. Moreover, it can be extremely 1476 difficult to determine the extent of deployment of systems making use 1477 of a particular value. However, in cases where the namespace is 1478 running out of unassigned values and additional ones are needed, it 1479 may be desirable to attempt to reclaim unused values. When 1480 reclaiming unused values, the following (at a minimum) should be 1481 considered: 1483 o Attempts should be made to contact the original party to which a 1484 value is assigned, to determine if the value was ever used, and if 1485 so, the extent of deployment. (In some cases, products were never 1486 shipped or have long ceased being used. In other cases, it may be 1487 known that a value was never actually used at all.) 1489 o Reassignments should not normally be made without the concurrence 1490 of the original requester. Reclamation under such conditions 1491 should only take place where there is strong evidence that a value 1492 is not widely used, and the need to reclaim the value outweighs 1493 the cost of a hostile reclamation. In any case, IESG Approval is 1494 needed in this case. 1496 o It may be appropriate to write up the proposed action and solicit 1497 comments from relevant user communities. In some cases, it may be 1498 appropriate to write an RFC that goes through a formal IETF 1499 process (including IETF Last Call) as was done when DHCP reclaimed 1500 some of its "Private Use" options [RFC3942]. 1502 o It may be useful to differentiate between revocation, release, and 1503 transfer. Revocation occurs when IANA removes an assignment, 1504 release occurs when the assignee initiates that removal, and 1505 transfer occurs when either revocation or release is coupled with 1506 immediate reassignment. It may be useful to specify procedures 1507 for each of these, or to explicitly prohibit combinations that are 1508 not desired. 1510 9.5. Contact Person vs Assignee or Owner 1512 Many registries include designation of a technical or administrative 1513 contact associated with each entry. Often, this is recorded as 1514 contact information for an individual. It is unclear, though, what 1515 role the individual has with respect to the registration: is this 1516 item registered on behalf of the individual, the company the 1517 individual worked for, or perhaps another organization the individual 1518 was acting for? 1519 This matters because some time later, when the individual has changed 1520 jobs or roles, and perhaps can no longer be contacted, someone might 1521 want to update the registration. IANA has no way to know what 1522 company, organization, or individual should be allowed to take the 1523 registration over. For registrations rooted in RFCs, the stream 1524 owner (such as the IESG or the IAB) can make an overriding decision. 1525 But in other cases, there is no recourse. 1527 Registries can include, in addition to a "Contact" field, an 1528 "Assignee" or "Owner" field (also referred to as "Change Controller") 1529 that can be used to address this situation, giving IANA clear 1530 guidance as to the actual owner of the registration. This is 1531 strongly advised especially for registries that do not require RFCs 1532 to manage their information (registries with policies such as First 1533 Come First Served Section 4.4, Expert Review Section 4.5, and 1534 Specification Required Section 4.6). Alternatively, organizations 1535 can put an organizational role into the "Contact" field in order to 1536 make their ownership clear. 1538 9.6. Closing or Obsoleting a Registry/Registrations 1540 Sometimes there is a request to "close" a registry to further 1541 registrations. When a registry is closed, no further registrations 1542 will be accepted. The information in the registry will still be 1543 valid and registrations already in the registry can still be updated. 1545 A closed registry can also be marked as "obsolete", as an indication 1546 that the information in the registry is no longer in current use. 1548 Specific entries in a registry can be marked as "obsolete" (no longer 1549 in use) or "deprecated" (use is not recommended). 1551 Such changes to registries and registered values are subject to 1552 normal change controls (see Section 2.3). Any closure, obsolescence, 1553 or deprecation serves to annotate the registry involved; the 1554 information in the registry remains there for informational and 1555 historic purposes. 1557 10. Appeals 1559 Appeals of protocol parameter registration decisions can be made 1560 using the normal IETF appeals process as described in [RFC2026], 1561 Section 6.5. That is, an initial appeal should be directed to the 1562 IESG, followed (if necessary) by an appeal to the IAB. 1564 11. Mailing Lists 1566 All IETF mailing lists associated with evaluating or discussing 1567 assignment requests as described in this document are subject to 1568 whatever rules of conduct and methods of list management are 1569 currently defined by Best Current Practices or by IESG decision. 1571 12. Security Considerations 1572 Information that creates or updates a registration needs to be 1573 authenticated and authorized. IANA updates registries according to 1574 instructions in published RFCs and from the IESG. It also may accept 1575 clarifications from document authors, relevant working group chairs, 1576 Designated Experts, and mail list participants, too. 1578 Information concerning possible security vulnerabilities of a 1579 protocol may change over time. Likewise, security vulnerabilities 1580 related to how an assigned number is used may change as well. As new 1581 vulnerabilities are discovered, information about such 1582 vulnerabilities may need to be attached to existing registrations, so 1583 that users are not misled as to the true security issues surrounding 1584 the use of a registered number. 1586 Security needs to be considered as part of the selection of a 1587 registration policy. For some protocols, registration of certain 1588 parameters will have security implications, and registration policies 1589 for the relevant registries must ensure that requests get appropriate 1590 review with those security implications in mind. 1592 An analysis of security issues is generally required for all 1593 protocols that make use of parameters (data types, operation codes, 1594 keywords, etc.) used in IETF protocols or registered by IANA. Such 1595 security considerations are usually included in the protocol document 1596 [RFC3552]. It is the responsibility of the IANA considerations 1597 associated with a particular registry to specify whether value- 1598 specific security considerations must be provided when assigning new 1599 values, and the process for reviewing such claims. 1601 13. IANA Considerations 1603 IANA is asked to update any references to RFC 5226 to now point to 1604 this document. 1606 14. Changes Relative to Earlier Editions of BCP 26 1608 14.1. 2016: Changes in This Document Relative to RFC 5226 1610 Significant additions: 1612 o Removed RFC 2119 key words, boilerplate, and reference, preferring 1613 plain English -- this is not a protocol specification. 1615 o Added Section 1.1, Keep IANA Considerations for IANA 1617 o Added Section 1.2, For More Information 1619 o Added Section 2.1, Hierarchical Registry Structure 1621 o Added best practice for selecting an appropriate policy into 1622 Section 4. 1624 o Added Section 4.12, Using Multiple Policies in Combination. 1626 o Added Section 2.3, Specifying Change Control for a Registry 1628 o Added Section 3.4, Early Allocations 1630 o Moved well-known policies into a separate section for each, 1631 subsections of Section 4. 1633 o Added Section 5.4, Expert Reviews and the Document Lifecycle 1635 o Added Section 7, Documentation References in IANA Registries 1637 o Added Section 8, What to Do in "bis" Documents 1639 o Added Section 9.5, Contact Person vs Assignee or Owner 1641 o Added Section 9.6, Closing or Obsoleting a Registry 1643 Clarifications and such: 1645 o Some reorganization -- moved text around for clarity and easier 1646 reading. 1648 o Made clarifications about identification of IANA registries and 1649 use of URLs for them. 1651 o Clarified the distinction between "Unassigned" and "Reserved". 1653 o Made some clarifications in "Expert Review" about instructions to 1654 the designated expert. 1656 o Made some clarifications in "Specification Required" about how to 1657 declare this policy. 1659 o Assorted minor clarifications and editorial changes throughout. 1661 14.2. 2008: Changes in RFC 5226 Relative to RFC 2434 1663 Changes include: 1665 o Major reordering of text to expand descriptions and to better 1666 group topics such as "updating registries" vs. "creating new 1667 registries", in order to make it easier for authors to find the 1668 text most applicable to their needs. 1670 o Numerous editorial changes to improve readability. 1672 o Changed the term "IETF Consensus" to "IETF Review" and added more 1673 clarifications. History has shown that people see the words "IETF 1674 Consensus" (without consulting the actual definition) and are 1675 quick to make incorrect assumptions about what the term means in 1676 the context of IANA Considerations. 1678 o Added "RFC Required" to list of defined policies. 1680 o Much more explicit directions and examples of "what to put in 1681 RFCs". 1683 o "Specification Required" now implies use of a Designated Expert to 1684 evaluate specs for sufficient clarity. 1686 o Significantly changed the wording in the Designated Experts 1687 section. Main purpose is to make clear that Expert Reviewers are 1688 accountable to the community, and to provide some guidance for 1689 review criteria in the default case. 1691 o Changed wording to remove any special appeals path. The normal 1692 RFC 2026 appeals path is used. 1694 o Added a section about reclaiming unused values. 1696 o Added a section on after-the-fact registrations. 1698 o Added a section indicating that mailing lists used to evaluate 1699 possible assignments (such as by a Designated Expert) are subject 1700 to normal IETF rules. 1702 15. Acknowledgments 1704 15.1. Acknowledgments for This Document (2016) 1706 Thomas Narten and Harald Tveit Alvestrand edited the two earlier 1707 editions of this document (RFCs 2434 and 5226), and Thomas continues 1708 his role in this third edition. Much of the text from RFC 5226 1709 remains in this edition. 1711 Thank you to Amanda Baber and Pearl Liang for their multiple reviews 1712 and suggestions for making this document as thorough as possible. 1714 This document has benefited from thorough review and comments by Tony 1715 Hansen, John Klensin, and Mark Nottingham. 1717 Special thanks to Mark Nottingham for reorganizing some of the text 1718 for better organization and readability, and to Tony Hansen for 1719 acting as document shepherd. 1721 15.2. Acknowledgments from the second edition (2008) 1723 The original acknowledgments section in RFC 5226 was: 1725 This document has benefited from specific feedback from Jari Arkko, 1726 Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Spencer 1727 Dawkins, Barbara Denny, Miguel Garcia, Paul Hoffman, Russ Housley, 1728 John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus 1729 Westerlund, and Bert Wijnen. 1731 15.3. Acknowledgments from the first edition (1998) 1732 The original acknowledgments section in RFC 2434 was: 1734 Jon Postel and Joyce Reynolds provided a detailed explanation on what 1735 IANA needs in order to manage assignments efficiently, and patiently 1736 provided comments on multiple versions of this document. Brian 1737 Carpenter provided helpful comments on earlier versions of the 1738 document. One paragraph in the Security Considerations section was 1739 borrowed from [RFC4288]. 1741 16. References 1743 16.1. Normative References 1745 [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 1746 3", BCP 9, RFC 2026, October 1996. 1748 16.2. Informative References 1750 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1751 1981. 1753 [RFC1591] Postel, J., "Domain Name System Structure and Delegation", 1754 RFC 1591, DOI 10.17487/RFC1591, March 1994, . 1757 [RFC2860] Carpenter, B., Baker, F. and M. Roberts, "Memorandum of 1758 Understanding Concerning the Technical Work of the 1759 Internet Assigned Numbers Authority", RFC 2860, June 2000. 1761 [RFC2939] Droms, R., "Procedures and IANA Guidelines for Definition 1762 of New DHCP Options and Message Types", BCP 43, RFC 2939, 1763 September 2000. 1765 [RFC3228] Fenner, B., "IANA Considerations for IPv4 Internet Group 1766 Management Protocol (IGMP)", BCP 57, RFC 3228, February 1767 2002. 1769 [RFC3406] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, 1770 "Uniform Resource Names (URN) Namespace Definition 1771 Mechanisms", BCP 66, RFC 3406, DOI 10.17487/RFC3406, 1772 October 2002, . 1774 [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC 1775 Text on Security Considerations", BCP 72, RFC 3552, July 1776 2003. 1778 [RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote 1779 Authentication Dial In User Service)", RFC 3575, July 1780 2003. 1782 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1783 Considered Useful", BCP 82, RFC 3692, January 2004. 1785 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J. and H. 1786 Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 1787 3748, June 2004. 1789 [RFC3942] Volz, B., "Reclassifying Dynamic Host Configuration 1790 Protocol version 4 (DHCPv4) Options", RFC 3942, November 1791 2004. 1793 [RFC3968] Camarillo, G., "The Internet Assigned Number Authority 1794 (IANA) Header Field Parameter Registry for the Session 1795 Initiation Protocol (SIP)", BCP 98, RFC 3968, December 1796 2004. 1798 [RFC4005] Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter 1799 Network Access Server Application", RFC 4005, August 2005. 1801 [RFC4025] Richardson, M., "A Method for Storing IPsec Keying 1802 Material in DNS", RFC 4025, March 2005. 1804 [RFC4044] McCloghrie, K., "Fibre Channel Management MIB", RFC 4044, 1805 May 2005. 1807 [RFC4124] Le Faucheur, F., "Protocol Extensions for Support of 1808 Diffserv-aware MPLS Traffic Engineering", RFC 4124, June 1809 2005. 1811 [RFC4169] Torvinen, V., Arkko, J. and M. Naslund, "Hypertext 1812 Transfer Protocol (HTTP) Digest Authentication Using 1813 Authentication and Key Agreement (AKA) Version-2", RFC 1814 4169, November 2005. 1816 [RFC4271] Rekhter, Y., Li, T. and S. Hares, "A Border Gateway 1817 Protocol 4 (BGP-4)", RFC 4271, January 2006. 1819 [RFC4283] Patel, A., Leung, K., Khalil, M., Akhtar, H. and K. 1820 Chowdhury, "Mobile Node Identifier Option for Mobile IPv6 1821 (MIPv6)", RFC 4283, November 2005. 1823 [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and 1824 Registration Procedures", BCP 13, RFC 4288, December 2005. 1826 [RFC4340] Kohler, E., Handley, M. and S. Floyd, "Datagram Congestion 1827 Control Protocol (DCCP)", RFC 4340, March 2006. 1829 [RFC4395] Hansen, T., Hardie, T. and L. Masinter, "Guidelines and 1830 Registration Procedures for New URI Schemes", BCP 35, RFC 1831 4395, February 2006. 1833 [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and 1834 Security Layer (SASL)", RFC 4422, June 2006. 1836 [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge 1837 Emulation (PWE3)", BCP 116, RFC 4446, April 2006. 1839 [RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) 1840 Considerations for the Lightweight Directory Access 1841 Protocol (LDAP)", BCP 64, RFC 4520, June 2006. 1843 [RFC4589] Schulzrinne, H. and H. Tschofenig, "Location Types 1844 Registry", RFC 4589, July 2006. 1846 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 1847 ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006. 1849 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1850 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 1852 [RFC5378] Bradner, S. and J. Contreras, "Rights Contributors Provide 1853 to the IETF Trust", BCP 78, RFC 5378, November 2008. 1855 [RFC5742] Alvestrand, H. and R. Housley, "IESG Procedures for 1856 Handling of Independent and IRTF Stream Submissions", BCP 1857 92, RFC 5742, December 2009. 1859 [RFC5771] Cotton, M., Vegoda, L. and D. Meyer, "IANA Guidelines for 1860 IPv4 Multicast Address Assignments", BCP 51, RFC 5771, 1861 March 2010. 1863 [RFC5795] Sandlund, K., Pelletier, G. and L-E. Jonsson, "The RObust 1864 Header Compression (ROHC) Framework", RFC 5795, March 1865 2010. 1867 [RFC6195] Eastlake, D., "Domain Name System (DNS) IANA 1868 Considerations", BCP 42, RFC 6195, March 2011. 1870 [RFC6275] Perkins, C., Johnson, D. and J. Arkko, "Mobility Support 1871 in IPv6", RFC 6275, July 2011. 1873 [RFC6709] Carpenter, B., Aboba, B. and S. Cheshire, "Design 1874 Considerations for Protocol Extensions", RFC 6709, 1875 September 2012. 1877 [RFC6994] Touch, J., "Shared Use of Experimental TCP Options", RFC 1878 6994, DOI 10.17487/RFC6994, August 2013, . 1881 [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code 1882 Points", BCP 100, RFC 7120, January 2014. 1884 [RFC7564] Saint-Andre, P. and M. Blanchet, "PRECIS Framework: 1885 Preparation, Enforcement, and Comparison of 1886 Internationalized Strings in Application Protocols", RFC 1887 7564, DOI 10.17487/RFC7564, May 2015, . 1890 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A. and 1891 S. Ray, "North-Bound Distribution of Link-State and 1892 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1893 DOI 10.17487/RFC7752, March 2016, . 1896 Authors' Addresses 1898 Michelle Cotton 1899 Internet Corporation for Assigned Names and Numbers 1900 12025 Waterfront Drive, Suite 300 1901 Los Angeles, CA 90094-2536 1902 US 1904 Phone: +1 310 823 9358 1905 Email: michelle.cotton@icann.org 1906 URI: https://www.icann.org/ 1908 Barry Leiba 1909 Huawei Technologies 1911 Phone: +1 646 827 0648 1912 Email: barryleiba@computer.org 1913 URI: http://internetmessagingtechnology.org/ 1915 Thomas Narten 1916 IBM Corporation 1917 3039 Cornwallis Ave., PO Box 12195 - BRQA/502 1918 Research Triangle Park, NC 27709-2195 1919 US 1921 Phone: +1 919 254 7798 1922 Email: narten@us.ibm.com