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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: December 01, 2016 IBM Corporation 8 June 01, 2016 10 Guidelines for Writing an IANA Considerations Section in RFCs 11 draft-leiba-cotton-iana-5226bis-15 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 December 01, 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 . . . . . . . . . 28 99 8. What to Do in "bis" Documents . . . . . . . . . . . . . . . . 28 100 9. Miscellaneous Issues . . . . . . . . . . . . . . . . . . . . . 30 101 9.1. When There Are No IANA Actions . . . . . . . . . . . . . . 30 102 9.2. Namespaces Lacking Documented Guidance . . . . . . . . . . 30 103 9.3. After-the-Fact Registrations . . . . . . . . . . . . . . . 30 104 9.4. Reclaiming Assigned Values . . . . . . . . . . . . . . . . 31 105 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 . . . . . . . . . . . . . . . . . . . . . . . . 33 110 12. Security Considerations . . . . . . . . . . . . . . . . . . . 33 111 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) . . . . . . 36 119 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 [RFC6838] 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 599 IANA normally takes its actions when a document is approved for 600 publication. There are times, though, when early allocation of a 601 value is important for the development of a technology: for example, 602 when early implementations are created while the document is still 603 under development. 605 IANA has a mechanism for handling such early allocations in some 606 cases. See [RFC7120] for details. It is usually not necessary to 607 explicitly mark a registry as allowing early allocation, because the 608 general rules will apply. 610 4. Choosing a Registration Policy, and Well-Known Policies 612 A registration policy is the policy that controls how new assignments 613 in a registry are accepted. There are several issues to consider 614 when defining the registration policy. 616 If the registry's namespace is limited, assignments will need to be 617 made carefully to prevent exhaustion. 619 Even when the space is essentially unlimited, it is still often 620 desirable to have at least a minimal review prior to assignment in 621 order to: 623 o prevent the hoarding of or unnecessary wasting of values. For 624 example, if the space consists of text strings, it may be 625 desirable to prevent entities from obtaining large sets of strings 626 that correspond to desirable names (existing company names, for 627 example). 629 o provide a sanity check that the request actually makes sense and 630 is necessary. Experience has shown that some level of minimal 631 review from a subject matter expert is useful to prevent 632 assignments in cases where the request is malformed or not 633 actually needed (for example, an existing assignment for an 634 essentially equivalent service already exists). 636 Perhaps most importantly, unreviewed extensions can impact 637 interoperability and security. See [RFC6709]. 639 When the namespace is essentially unlimited and there are no 640 potential interoperability or security issues, assigned numbers can 641 usually be given out to anyone without any subjective review. In 642 such cases, IANA can make assignments directly, provided that IANA is 643 given detailed instructions on what types of requests it should 644 grant, and it is able to do so without exercising subjective 645 judgement. 647 When this is not the case, some level of review is required. 648 However, it's important to balance adequate review and ease of 649 registration. In many cases, those making registrations will not be 650 IETF participants; requests often come from other standards 651 organizations, from organizations not directly involved in standards, 652 from ad-hoc community work (from an open-source project, for 653 example), and so on. Registration must not be unnecessarily 654 difficult, unnecessarily costly (in terms of time and other 655 resources), nor unnecessarily subject to denial. 657 While it is sometimes necessary to restrict what gets registered 658 (e.g., for limited resources such as bits in a byte, or for items for 659 which unsupported values can be damaging to protocol operation), in 660 many cases having what's in use represented in the registry is more 661 important. Overly strict review criteria and excessive cost (in time 662 and effort) discourage people from even attempting to make a 663 registration. If a registry fails to reflect the protocol elements 664 actually in use, it can adversely affect deployment of protocols on 665 the Internet, and the registry itself is devalued. 667 Therefore, it is important to think specifically about the 668 registration policy, and not just pick one arbitrarily or nor copy 669 text from another document. Working groups and other document 670 developers should use care in selecting appropriate registration 671 policies when their documents create registries. They should select 672 the least strict policy that suits a registry's needs, and look for 673 specific justification for policies that require significant 674 community involvement (those stricter than Expert Review or 675 Specification Required, in terms of the well-known policies). The 676 needs here will vary from registry to registry, and, indeed, over 677 time, and this BCP will not be the last word on the subject. 679 The following policies are defined for common usage. These cover a 680 range of typical policies that have been used to describe the 681 procedures for assigning new values in a namespace. It is not 682 strictly required that documents use these terms; the actual 683 requirement is that the instructions to IANA be clear and 684 unambiguous. However, use of these terms is strongly recommended 685 because their meanings are widely understood. Newly minted policies, 686 including ones that combine the elements of procedures associated 687 with these terms in novel ways, may be used if none of these policies 688 are suitable; it will help the review process if an explanation is 689 included as to why that is the case. The terms are fully explained 690 in the following subsections. 692 1. Private Use 693 2. Experimental Use 694 3. Hierarchical Allocation 695 4. First Come First Served 696 5. Expert Review 697 6. Specification Required 698 7. RFC Required 699 8. IETF Review 700 9. Standards Action 701 10. IESG Approval 703 It should be noted that it often makes sense to partition a namespace 704 into multiple categories, with assignments within each category 705 handled differently. Many protocols now partition namespaces into 706 two or more parts, with one range reserved for Private or 707 Experimental Use while other ranges are reserved for globally unique 708 assignments assigned following some review process. Dividing a 709 namespace into ranges makes it possible to have different policies in 710 place for different ranges and different use cases. 712 Similarly, it will often be useful to specify multiple policies in 713 parallel, with each policy being used under different circumstances. 714 For more discussion of that topic, see Section 4.12. 716 Examples of RFCs that specify multiple policies in parallel: 718 LDAP [RFC4520] 719 TLS ClientCertificateType Identifiers [RFC5246] (as detailed in 720 the subsections below) 721 MPLS Pseudowire Types Registry [RFC4446] 723 4.1. Private Use 725 For private or local use only, with the type and purpose defined by 726 the local site. No attempt is made to prevent multiple sites from 727 using the same value in different (and incompatible) ways. IANA does 728 not record assignments from registries or ranges with this policy 729 (and therefore there is no need for IANA to review them) and 730 assignments are not generally useful for broad interoperability. It 731 is the responsibility of the sites making use of the Private Use 732 range to ensure that no conflicts occur (within the intended scope of 733 use). 735 Examples: 737 Site-specific options in DHCP [RFC2939] 738 Fibre Channel Port Type Registry [RFC4044] 739 TLS ClientCertificateType Identifiers 224-255 [RFC5246] 741 4.2. Experimental Use 743 Experimental Use is similar to Private Use, but with the purpose 744 being to facilitate experimentation. See [RFC3692] for details. 745 IANA does not record assignments from registries or ranges with this 746 policy (and therefore there is no need for IANA to review them) and 747 assignments are not generally useful for broad interoperability. 749 Unless the registry explicitly allows it, it is not appropriate for 750 documents to select explicit values from registries or ranges with 751 this policy. Specific experiments will select a value to use during 752 the experiment. 754 When code points are set aside for experimental use, it's important 755 to make clear any expected restrictions on experimental scope. For 756 example, say whether it's acceptable to run experiments using those 757 code points over the open Internet, or whether such experiments 758 should be confined to more closed environments. See [RFC6994] for an 759 example of such considerations. 761 Example: 763 Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP 764 Headers [RFC4727] 766 4.3. Hierarchical Allocation 768 With Hierarchical Allocation, delegated administrators are given 769 control over part of the namespace, and can assign values in that 770 part of the namespace. IANA makes allocations in the higher levels 771 of the namespace according to one of the other policies. 773 Examples: 775 - DNS names. IANA manages the top-level domains (TLDs), and, as 776 [RFC1591] says: 778 Under each TLD may be created a hierarchy of names. Generally, 779 under the generic TLDs the structure is very flat. That is, 780 many organizations are registered directly under the TLD, and 781 any further structure is up to the individual organizations. 783 - Object Identifiers, defined by ITU-T recommendation X.208. 784 According to , some registries 785 include 787 * IANA, which hands out OIDs the "Private Enterprises" branch, 788 * ANSI, which hands out OIDs under the "US Organizations" branch, 789 and 790 * BSI, which hands out OIDs under the "UK Organizations" branch. 792 - URN namespaces. IANA registers URN Namespace IDs (NIDs [RFC3406]), 793 and the organization registering an NID is responsible for 794 allocations of URNs within that namespace. 796 4.4. First Come First Served 797 For the First Come First Served policy, assignments are made to 798 anyone on a first come, first served basis. There is no substantive 799 review of the request, other than to ensure that it is well-formed 800 and doesn't duplicate an existing assignment. However, requests must 801 include a minimal amount of clerical information, such as a point of 802 contact (including an email address, and sometimes a postal address) 803 and a brief description of how the value will be used. Additional 804 information specific to the type of value requested may also need to 805 be provided, as defined by the namespace. For numbers, IANA 806 generally assigns the next in-sequence unallocated value, but other 807 values may be requested and assigned if an extenuating circumstance 808 exists. With names, specific text strings can usually be requested. 810 When creating a new registry with First Come First Served as the 811 registration policy, in addition to the contact person field or 812 reference, the registry should contain a field for change controller. 813 Having a change controller for each entry for these types of 814 registrations makes authorization of future modifications more clear. 815 See Section 2.3. 817 It is important that changes to the registration of a First Come 818 First Served code point retain compatibility with the current usage 819 of that code point, and so changes need to be made with care. The 820 change controller should not, in most cases, be requesting 821 incompatible changes nor repurposing a registered code point. See 822 also Section 9.4 and Section 9.5. 824 A working group or any other entity that is developing a protocol 825 based on a First Come First Served code point has to be extremely 826 careful that the protocol retains wire compatibility with current use 827 of the code point. Once that is no longer true, the new work needs 828 to change to a different code point (and register that use at the 829 appropriate time). 831 It is also important to understand that First Come First Served 832 really has no filtering. Essentially, any well formed request is 833 accepted. 835 Examples: 837 SASL mechanism names [RFC4422] 838 LDAP Protocol Mechanisms and LDAP Syntax [RFC4520] 840 4.5. Expert Review 842 (Also called "Designated Expert" in earlier editions of this 843 document.) For the Expert Review policy, review and approval by a 844 designated expert (see Section 5) is required. 846 The required documentation and review criteria, giving clear guidance 847 to the designated expert, should be provided when defining the 848 registry. It is particularly important to lay out what should be 849 considered when performing an evaluation and reasons for rejecting a 850 request. It is also a good idea to include, when possible, a sense 851 of whether many registrations are expected over time, or if the 852 registry is expected to be updated infrequently or in exceptional 853 circumstances only. 855 Thorough understanding of Section 5 is important when deciding on an 856 Expert Review policy and designing the guidance to the designated 857 expert. 859 Good examples of guidance to designated experts: 861 Extensible Authentication Protocol (EAP) [RFC3748], Sections 6 and 862 7.2 863 North-Bound Distribution of Link-State and TE Information using 864 BGP [RFC7752], Section 5.1 866 When creating a new registry with Expert Review as the registration 867 policy, in addition to the contact person field or reference, the 868 registry should contain a field for change controller. Having a 869 change controller for each entry for these types of registrations 870 makes authorization of future modifications more clear. See Section 871 2.3 873 Examples: 875 EAP Method Types [RFC3748] 876 HTTP Digest AKA algorithm versions [RFC4169] 877 URI schemes [RFC4395] 878 GEOPRIV Location Types [RFC4589] 880 4.6. Specification Required 882 For the Specification Required policy, review and approval by a 883 designated expert (see Section 5) is required, and the values and 884 their meanings must be documented in a permanent and readily 885 available public specification, in sufficient detail so that 886 interoperability between independent implementations is possible. 887 The designated expert will review the public specification and 888 evaluate whether it is sufficiently stable and permanent, and 889 sufficiently clear to allow interoperable implementations. 891 The intention behind "permanent and readily available" is that a 892 document can reasonably be expected to be findable and retrievable 893 long after IANA assignment of the requested value. Publication of an 894 RFC is an ideal means of achieving this requirement, but 895 Specification Required is intended to also cover the case of a 896 document published outside of the RFC path, including informal 897 documentation. 899 For RFC publication, formal review by the designated expert is still 900 requested, but the normal RFC review process is expected to provide 901 the necessary review for interoperability. The designated expert's 902 review is still important, but it's equally important to note that 903 when there is IETF consensus, the expert can sometimes be "in the 904 rough" (see also the last paragraph of Section 5.4). 906 As with Expert Review (Section 4.5), clear guidance to the designated 907 expert, should be provided when defining the registry, and thorough 908 understanding of Section 5 is important. 910 When specifying this policy, just use the term "Specification 911 Required". Some specifications have chosen to refer to it as "Expert 912 Review with Specification Required", and that only causes confusion. 914 Examples: 916 Diffserv-aware TE Bandwidth Constraints Model Identifiers 917 [RFC4124] 918 TLS ClientCertificateType Identifiers 64-223 [RFC5246] 919 ROHC Profile Identifiers [RFC5795] 921 4.7. RFC Required 923 With the RFC Required policy, the registration request, along with 924 associated documentation, must be published in an RFC. The RFC need 925 not be in the IETF stream, but may be in any RFC stream (currently an 926 RFC may be in the IETF, IRTF, or IAB stream, or an RFC Editor 927 Independent Submission [RFC5742]). 929 Unless otherwise specified, any type of RFC is sufficient (currently 930 Standards Track, BCP, Informational, Experimental, or Historic). 932 4.8. IETF Review 934 (Formerly called "IETF Consensus" in the first edition of this 935 document.) With the IETF Review policy, new values are assigned only 936 through RFCs in the IETF Stream -- those that have been shepherded 937 through the IESG as AD-Sponsored or IETF working group Documents 938 [RFC2026] [RFC5378], have gone through IETF last call, and that the 939 IESG has approved as having IETF consensus. 941 The intent is that the document and proposed assignment will be 942 reviewed by the IETF community (including appropriate IETF working 943 groups, directorates, and other experts) and by the IESG, to ensure 944 that the proposed assignment will not negatively affect 945 interoperability or otherwise extend IETF protocols in an 946 inappropriate or damaging manner. To ensure adequate community 947 review, such documents will always undergo an IETF Last Call. 949 Unless otherwise specified, any type of RFC is sufficient (currently 950 Standards Track, BCP, Informational, Experimental, or Historic). 952 Examples: 954 IPSECKEY Algorithm Types [RFC4025] 955 Accounting-Auth-Method AVP values in DIAMETER [RFC4005] 956 TLS Extension Types [RFC5246] 958 4.9. Standards Action 960 For the Standards Action policy, values are assigned only through 961 Standards Track or Best Current Practice RFCs in the IETF Stream. 963 Examples: 965 BGP message types [RFC4271] 966 Mobile Node Identifier option types [RFC4283] 967 TLS ClientCertificateType Identifiers 0-63 [RFC5246] 968 DCCP Packet Types [RFC4340] 970 4.10. IESG Approval 972 New assignments may be approved by the IESG. Although there is no 973 requirement that the request be documented in an RFC, the IESG has 974 discretion to request documents or other supporting materials on a 975 case-by-case basis. 977 IESG Approval is not intended to be used often or as a "common case"; 978 indeed, it has seldom been used in practice. Rather, it is intended 979 to be available in conjunction with other policies as a fall-back 980 mechanism in the case where one of the other allowable approval 981 mechanisms cannot be employed in a timely fashion or for some other 982 compelling reason. IESG Approval is not intended to circumvent the 983 public review processes implied by other policies that could have 984 been employed for a particular assignment. IESG Approval would be 985 appropriate, however, in cases where expediency is desired and there 986 is strong consensus (such as from a working group) for making the 987 assignment. 989 Before approving a request, the IESG might consider consulting the 990 community, via a "call for comments" that provides as much 991 information as is reasonably possible about the request. 993 Examples: 995 IPv4 Multicast address assignments [RFC5771] 996 IPv4 IGMP Type and Code values [RFC3228] 997 Mobile IPv6 Mobility Header Type and Option values [RFC6275] 999 4.11. Using the Well-Known Registration Policies 1001 Because the well-known policies benefit from both community 1002 experience and wide understanding, their use is encouraged, and the 1003 making up of new policies needs to be accompanied by reasonable 1004 justification. 1006 It is also acceptable to cite one of the well-known policies and 1007 include additional guidelines for what kind of considerations should 1008 be taken into account by the review process. 1010 For example, RADIUS [RFC3575] specifies the use of a Designated 1011 Expert, but includes specific additional criteria the Designated 1012 Expert should follow. 1014 The well-known policies from "First Come First Served" to "Standards 1015 Action" specify a range of policies in increasing order of strictness 1016 (using the numbering from the full list in Section 4): 1018 4. First Come First Served 1019 No review, minimal documentation. 1021 5/6. Expert Review / Specification Required 1022 Expert review with sufficient documentation for review. / 1023 Significant stable public documentation sufficient for 1024 interoperability. 1026 7. RFC Required 1027 Any RFC publication, IETF or a non-IETF Stream. 1029 8. IETF Review 1030 RFC publication, IETF Stream only, but need not be Standards 1031 Track. 1033 9. Standards Action 1034 RFC publication, IETF Stream, Standards Track or BCP only. 1036 Examples of situations that might merit IETF Review or Standards 1037 Action include the following: 1039 o When a resource is limited, such as bits in a byte (or in two 1040 bytes, or four), or numbers in a limited range. In these cases, 1041 allowing registrations that haven't been carefully reviewed and 1042 agreed by community consensus could too quickly deplete the 1043 allowable values. 1045 o When thorough community review is necessary to avoid extending or 1046 modifying the protocol in ways that could be damaging. One 1047 example is in defining new command codes, as opposed to options 1048 that use existing command codes: the former might require a strict 1049 policy, where a more relaxed policy could be adequate for the 1050 latter. Another example is in defining protocol elements that 1051 change the semantics of existing operations. 1053 o When there are security implications with respect to the resource, 1054 and thorough review is needed to ensure that the new usage is 1055 sound. Examples of this include lists of acceptable hashing and 1056 cryptographic algorithms, and assignment of transport ports in the 1057 system range. 1059 When reviewing a document that asks IANA to create a new registry or 1060 change a registration policy to any policy more stringent than Expert 1061 Review or Specification Required, the IESG should ask for 1062 justification to ensure that more relaxed policies have been 1063 considered and that the strict policy is the right one. 1065 Accordingly, document developers need to anticipate this and document 1066 their considerations for selecting the specified policy (ideally, in 1067 the document itself; failing that, in the shepherd writeup). 1068 Likewise, the document shepherd should ensure that the selected 1069 policies have been justified before sending the document to the IESG. 1071 When specifications are revised, registration policies should be 1072 reviewed in light of experience since the policies were set. 1074 4.12. Using Multiple Policies in Combination 1076 In some situations, it is necessary to define multiple registration 1077 policies. For example, registrations through the normal IETF process 1078 might use one policy, while registrations from outside the process 1079 would have a different policy applied. 1081 Thus, a particular registry might want to use a policy such as "RFC 1082 Required" or "IETF Review" sometimes, with a designated expert 1083 checking a "Specification Required" policy at other times. 1085 The alternative to using a combination requires either that all 1086 requests come through RFCs or that requests in RFCs go through review 1087 by the designated expert, even though they already have IETF review 1088 and consensus. 1090 This can be documented in the IANA Considerations section when the 1091 registry is created: 1093 IANA is asked to create the registry "Fruit Access Flags" under 1094 the "Fruit Parameters" group. New registrations will be permitted 1095 through either the IETF Review policy or the Specification 1096 Required policy [BCP26]. The latter should be used only for 1097 registrations requested by SDOs outside the IETF. Registrations 1098 requested in IETF documents will be subject to IETF review. 1100 Such combinations will commonly use one of {Standards Action, IETF 1101 Review, RFC Required} in combination with one of {Specification 1102 Required, Expert Review}. Guidance should be provided about when 1103 each policy is appropriate, as in the example above. 1105 5. Designated Experts 1107 5.1. The Motivation for Designated Experts 1109 Discussion on a mailing list can provide valuable technical feedback, 1110 but opinions often vary and discussions may continue for some time 1111 without clear resolution. In addition, IANA cannot participate in 1112 all of these mailing lists and cannot determine if or when such 1113 discussions reach consensus. Therefore, IANA relies on a "designated 1114 expert" for advice regarding the specific question of whether an 1115 assignment should be made. The designated expert is an individual 1116 who is responsible for carrying out an appropriate evaluation and 1117 returning a recommendation to IANA. 1119 It should be noted that a key motivation for having designated 1120 experts is for the IETF to provide IANA with a subject matter expert 1121 to whom the evaluation process can be delegated. IANA forwards 1122 requests for an assignment to the expert for evaluation, and the 1123 expert (after performing the evaluation) informs IANA as to whether 1124 or not to make the assignment or registration. In most cases, the 1125 registrants do not work directly with the designated experts. The 1126 list of designated experts for a registry is listed in the registry. 1128 It will often be useful to use a designated expert only some of the 1129 time, as a supplement to other processes. For more discussion of 1130 that topic, see Section 4.12. 1132 5.2. The Role of the Designated Expert 1134 The designated expert is responsible for coordinating the appropriate 1135 review of an assignment request. The review may be wide or narrow, 1136 depending on the situation and the judgment of the designated expert. 1137 This may involve consultation with a set of technology experts, 1138 discussion on a public mailing list, consultation with a working 1139 group (or its mailing list if the working group has disbanded), etc. 1140 Ideally, the designated expert follows specific review criteria as 1141 documented with the protocol that creates or uses the namespace. See 1142 the IANA Considerations sections of [RFC3748] and [RFC3575] for 1143 specific examples. 1145 Designated experts are expected to be able to defend their decisions 1146 to the IETF community, and the evaluation process is not intended to 1147 be secretive or bestow unquestioned power on the expert. Experts are 1148 expected to apply applicable documented review or vetting procedures, 1149 or in the absence of documented criteria, follow generally accepted 1150 norms such as those in Section 5.3. Designated experts are generally 1151 not expected to be "gatekeepers", setting out to make registrations 1152 difficult to obtain, unless the guidance in the defining document 1153 specifies that they should act as such. Absent stronger guidance, 1154 the experts should be evaluating registration requests for 1155 completeness, interoperability, and conflicts with existing protocols 1156 and options. 1158 It has proven useful to have multiple designated experts for some 1159 registries. Sometimes those experts work together in evaluating a 1160 request, while in other cases additional experts serve as backups, 1161 acting only when the primary expert is unavailable. In registries 1162 with a pool of experts, the pool often has a single chair responsible 1163 for defining how requests are to be assigned to and reviewed by 1164 experts. In other cases, IANA might assign requests to individual 1165 members in sequential or approximate random order. The document 1166 defining the registry can, if it's appropriate for the situation, 1167 specify how the group should work -- for example, it might be 1168 appropriate to specify rough consensus on a mailing list, within a 1169 related working group, or among a pool of designated experts. 1171 In cases of disagreement among multiple experts, it is the 1172 responsibility of those experts to make a single clear recommendation 1173 to IANA. It is not appropriate for IANA to resolve disputes among 1174 experts. In extreme situations, such as deadlock, the designating 1175 body may need to step in to resolve the problem. 1177 If a designated expert is conflicted for a particular review (is, for 1178 example, an author or significant proponent of a specification 1179 related to the registration under review), that expert should recuse 1180 himself. In the event that all the designated experts are 1181 conflicted, they should ask that a temporary expert be designated for 1182 the conflicted review. 1184 This document defines the designated expert mechanism with respect to 1185 documents in the IETF stream only. Documents in other streams may 1186 use a registration policy that requires a designated expert only if 1187 those streams (or those documents) specify how designated experts are 1188 appointed and managed. What is described below, with management by 1189 the IESG, is only appropriate for the IETF stream. 1191 5.2.1. Managing Designated Experts in the IETF 1192 Designated experts for registries created by the IETF are appointed 1193 by the IESG, normally upon recommendation by the relevant Area 1194 Director. They may be appointed at the time a document creating or 1195 updating a namespace is approved by the IESG, or subsequently, when 1196 the first registration request is received. Because experts 1197 originally appointed may later become unavailable, the IESG will 1198 appoint replacements as necessary. The IESG may remove any 1199 designated expert that it appointed, at its discretion. 1201 The normal appeals process, as described in [RFC2026], Section 6.5.1, 1202 applies to issues that arise with the designated expert team. For 1203 this purpose, the designated expert team takes the place of the 1204 working group in that description. 1206 5.3. Designated Expert Reviews 1208 In the years since RFC 2434 was published and has been put to use, 1209 experience has led to the following observations: 1211 o A designated expert must respond in a timely fashion, normally 1212 within a week for simple requests to a few weeks for more complex 1213 ones. Unreasonable delays can cause significant problems for 1214 those needing assignments, such as when products need code points 1215 to ship. This is not to say that all reviews can be completed 1216 under a firm deadline, but they must be started, and the requester 1217 and IANA should have some transparency into the process if an 1218 answer cannot be given quickly. 1220 o If a designated expert does not respond to IANA's requests within 1221 a reasonable period of time, either with a response or with a 1222 reasonable explanation for the delay (some requests may be 1223 particularly complex), and if this is a recurring event, IANA must 1224 raise the issue with the IESG. Because of the problems caused by 1225 delayed evaluations and assignments, the IESG should take 1226 appropriate actions to ensure that the expert understands and 1227 accepts his or her responsibilities, or appoint a new expert. 1229 o The designated expert is not required to personally bear the 1230 burden of evaluating and deciding all requests, but acts as a 1231 shepherd for the request, enlisting the help of others as 1232 appropriate. In the case that a request is denied, and rejecting 1233 the request is likely to be controversial, the expert should have 1234 the support of other subject matter experts. That is, the expert 1235 must be able to defend a decision to the community as a whole. 1237 When a designated expert is used, the documentation should give clear 1238 guidance to the designated expert, laying out criteria for performing 1239 an evaluation and reasons for rejecting a request. In the case where 1240 there are no specific documented criteria, the presumption should be 1241 that a code point should be granted unless there is a compelling 1242 reason to the contrary. Reasons that have been used to deny requests 1243 have included these: 1245 o Scarcity of code points, where the finite remaining code points 1246 should be prudently managed, or where a request for a large number 1247 of code points is made and a single code point is the norm. 1249 o Documentation is not of sufficient clarity to evaluate or ensure 1250 interoperability. 1252 o The code point is needed for a protocol extension, but the 1253 extension is not consistent with the documented (or generally 1254 understood) architecture of the base protocol being extended, and 1255 would be harmful to the protocol if widely deployed. It is not 1256 the intent that "inconsistencies" refer to minor differences "of a 1257 personal preference nature". Instead, they refer to significant 1258 differences such as inconsistencies with the underlying security 1259 model, implying a change to the semantics of an existing message 1260 type or operation, requiring unwarranted changes in deployed 1261 systems (compared with alternate ways of achieving a similar 1262 result), etc. 1264 o The extension would cause problems with existing deployed systems. 1266 o The extension would conflict with one under active development by 1267 the IETF, and having both would harm rather than foster 1268 interoperability. 1270 When a designated expert is used, documents must not name the 1271 designated expert in the document itself; instead, any suggested 1272 names should be relayed to the appropriate Area Director at the time 1273 the document is sent to the IESG for approval. This is usually done 1274 in the document shepherd writeup. 1276 If the request should also be reviewed on a specific public mailing 1277 list, its address should be specified. 1279 5.4. Expert Reviews and the Document Lifecycle 1281 Review by the designated expert is necessarily done at a particular 1282 point in time, and represents review of a particular version of the 1283 document. While reviews are generally done around the time of IETF 1284 last call, deciding when the review should take place is a question 1285 of good judgment. And while re-reviews might be done when it's 1286 acknowledged that the documentation of the registered item has 1287 changed substantially, making sure that re-review happens requires 1288 attention and care. 1290 It is possible, through carelessness, accident, inattentiveness, or 1291 even willful disregard, that changes might be made after the 1292 designated expert's review and approval that would, if the document 1293 were re-reviewed, cause the expert not to approve the registration. 1294 It is up to the IESG, with the token held by the responsible Area 1295 Director, to be alert to such situations and to recognize that such 1296 changes need to be checked. 1298 For registrations made from documents on the Standards Track, there 1299 is often expert review required (by the registration policy) in 1300 addition to IETF consensus (for approval as a Standards Track RFC). 1301 In such cases, the review by the designated expert needs to be 1302 timely, submitted before the IESG evaluates the document. The IESG 1303 should generally not hold the document up waiting for late review. 1304 It is also not intended for the expert review to override IETF 1305 consensus: the IESG should consider the review in its own evaluation, 1306 as it would do for other last-call reviews. 1308 6. Well-Known Registration Status Terminology 1310 The following labels describe the status of an assignment or range of 1311 assignments: 1313 Private Use: Private use only (not assigned), as described in 1314 Section 4.1. 1316 Experimental: Available for general experimental use as described 1317 in [RFC3692]. IANA does not record specific assignments for 1318 any particular use. 1320 Unassigned: Not currently assigned, and available for assignment 1321 via documented procedures. While it's generally clear that 1322 any values that are not registered are unassigned and 1323 available for assignment, it is sometimes useful to 1324 explicitly specify that situation. Note that this is 1325 distinctly different from "Reserved". 1327 Reserved: Not assigned and not available for assignment. Reserved 1328 values are held for special uses, such as to extend the 1329 namespace when it becomes exhausted. "Reserved" is also 1330 sometimes used to designate values that had been assigned 1331 but are no longer in use, keeping them set aside as long as 1332 other unassigned values are available. Note that this is 1333 distinctly different from "Unassigned". 1335 Reserved values can be released for assignment by the change 1336 controller for the registry (this is often the IESG, for 1337 registries created by RFCs in the IETF stream). 1339 Known Unregistered Use: It's known that the assignment or range is 1340 in use without having been defined in accordance with 1341 reasonable practice. Documentation for use of the 1342 assignment or range may be unavailable, inadequate, or 1343 conflicting. This is a warning against use, as well as an 1344 alert to network operators, who might see these values in 1345 use on their networks. 1347 7. Documentation References in IANA Registries 1349 Usually, registries and registry entries include references to 1350 documentation (RFCs or other documents). The purpose of these 1351 references is to provide pointers for implementors to find details 1352 necessary for implementation, NOT to simply note what document 1353 created the registry or entry. Therefore: 1355 o If a document registers an item that is defined and explained 1356 elsewhere, the registered reference should be to the document 1357 containing the definition, not to the document that is merely 1358 performing the registration. 1360 o If the registered item is defined and explained in the current 1361 document, it is important to include sufficient information to 1362 enable implementors to understand the item and to create a proper 1363 implementation. 1365 o If the registered item is explained primarily in a specific 1366 section of the reference document, it is useful to include a 1367 section reference. For example, "[RFC4637], Section 3.2", rather 1368 than just "[RFC4637]". 1370 o For documentation of a new registry, the reference should provide 1371 information about the registry itself, not just a pointer to the 1372 creation of it. Useful information includes the purpose of the 1373 registry, a rationale for its creation, documentation of the 1374 process and policy for new registrations, guidelines for new 1375 registrants or designated experts, and other such related 1376 information. But note that, while it's important to include this 1377 information in the document, it needn't all be in the IANA 1378 Considerations section. See Section 1.1. 1380 8. What to Do in "bis" Documents 1382 On occasion, an RFC is issued that obsoletes a previous edition of 1383 the same document. We sometimes call these "bis" documents, such as 1384 when RFC 4637 is obsoleted by draft-ietf-foo-rfc4637bis. When the 1385 original document created registries and/or registered entries, there 1386 is a question of how to handle the IANA Considerations section in the 1387 "bis" document. 1389 If the registrations specify the original document as a reference, 1390 those registrations should be updated to point to the current (not 1391 obsolete) documentation for those items. Usually, that will mean 1392 changing the reference to be the "bis" document. 1394 There will, though, be times when a document updates another, but 1395 does not make it obsolete, and the definitive reference is changed 1396 for some items but not for others. Be sure that the references are 1397 always set to point to the correct, current documentation for each 1398 item. 1400 For example, suppose RFC 4637 registered the "BANANA" flag in the 1401 "Fruit Access Flags" registry, and the documentation for that flag is 1402 in Section 3.2. 1404 The current registry might look, in part, like this: 1406 Name Description Reference 1407 -------- ------------------- --------- 1408 BANANA Flag for bananas [RFC4637], Section 3.2 1410 If draft-ietf-foo-rfc4637bis obsoletes RFC 4637 and, because of some 1411 rearrangement, now documents the flag in Section 4.1.2, the IANA 1412 Considerations of the bis document might contain text such as this: 1414 IANA is asked to change the registration information for the 1415 BANANA flag in the "Fruit Access Flags" registry to the following: 1417 Name Description Reference 1418 -------- ------------------- --------- 1419 BANANA Flag for bananas [[this RFC]], Section 4.2.1 1421 In many cases, if there are a number of registered references to the 1422 original RFC and the document organization has not changed the 1423 registered section numbering much, it may simply be reasonable to do 1424 this: 1426 Because this document obsoletes RFC 4637, IANA is asked to change 1427 all registration information that references [RFC4637] to instead 1428 reference [[this RFC]]. 1430 If information for registered items has been or is being moved to 1431 other documents, then, of course, the registration information should 1432 be changed to point to those other documents. In no case is it 1433 reasonable to leave documentation pointers to the obsoleted document 1434 for any registries or registered items that are still in current use. 1436 It is extremely important to be clear in your instructions regarding 1437 updating references, especially in cases where some references need 1438 to be updated and others do not. 1440 9. Miscellaneous Issues 1442 9.1. When There Are No IANA Actions 1444 Before an Internet-Draft can be published as an RFC, IANA needs to 1445 know what actions (if any) it needs to perform. Experience has shown 1446 that it is not always immediately obvious whether a document has no 1447 IANA actions, without reviewing the document in some detail. In 1448 order to make it clear to IANA that it has no actions to perform (and 1449 that the author has consciously made such a determination), such 1450 documents should, after the authors confirm that this is the case, 1451 include an IANA Considerations section that states: 1453 This document has no IANA actions. 1455 IANA prefers that these "empty" IANA Considerations sections be left 1456 in the document for the record: it makes it clear later on that the 1457 document explicitly said that no IANA actions were needed (and that 1458 it wasn't just omitted). This is a change from the prior practice of 1459 requesting that such sections be removed by the RFC Editor, and 1460 authors are asked to accommodate this change. 1462 9.2. Namespaces Lacking Documented Guidance 1464 For all existing RFCs that either explicitly or implicitly rely on 1465 IANA to make assignments without specifying a precise assignment 1466 policy, IANA (in consultation with the IESG) will continue to decide 1467 what policy is appropriate. Changes to existing policies can always 1468 be initiated through the normal IETF consensus process, or through 1469 the IESG when appropriate. 1471 All future RFCs that either explicitly or implicitly rely on IANA to 1472 register or otherwise administer namespace assignments must provide 1473 guidelines for administration of the namespace. 1475 9.3. After-the-Fact Registrations 1477 Occasionally, the IETF becomes aware that an unassigned value from a 1478 namespace is in use on the Internet or that an assigned value is 1479 being used for a different purpose than it was registered for. The 1480 IETF does not condone such misuse; procedures of the type described 1481 in this document need to be applied to such cases, and it might not 1482 always be possible to formally assign the desired value. In the 1483 absence of specifications to the contrary, values may only be 1484 reassigned for a different purpose with the consent of the original 1485 assignee (when possible) and with due consideration of the impact of 1486 such a reassignment. In cases of likely controversy, consultation 1487 with the IESG is advised. 1489 This is part of the reason for the advice in Section 3.1 about using 1490 placeholder values, such as "TBD1", during document development: open 1491 use of unregistered values after results from well-meant, early 1492 implementations, where the implementations retained the use of 1493 developmental code points that never proceeded to a final IANA 1494 assignment. 1496 9.4. Reclaiming Assigned Values 1498 Reclaiming previously assigned values for reuse is tricky, because 1499 doing so can lead to interoperability problems with deployed systems 1500 still using the assigned values. Moreover, it can be extremely 1501 difficult to determine the extent of deployment of systems making use 1502 of a particular value. However, in cases where the namespace is 1503 running out of unassigned values and additional ones are needed, it 1504 may be desirable to attempt to reclaim unused values. When 1505 reclaiming unused values, the following (at a minimum) should be 1506 considered: 1508 o Attempts should be made to contact the original party to which a 1509 value is assigned, to determine if the value was ever used, and if 1510 so, the extent of deployment. (In some cases, products were never 1511 shipped or have long ceased being used. In other cases, it may be 1512 known that a value was never actually used at all.) 1514 o Reassignments should not normally be made without the concurrence 1515 of the original requester. Reclamation under such conditions 1516 should only take place where there is strong evidence that a value 1517 is not widely used, and the need to reclaim the value outweighs 1518 the cost of a hostile reclamation. In any case, IESG Approval is 1519 needed in this case. 1521 o It may be appropriate to write up the proposed action and solicit 1522 comments from relevant user communities. In some cases, it may be 1523 appropriate to write an RFC that goes through a formal IETF 1524 process (including IETF Last Call) as was done when DHCP reclaimed 1525 some of its "Private Use" options [RFC3942]. 1527 o It may be useful to differentiate between revocation, release, and 1528 transfer. Revocation occurs when IANA removes an assignment, 1529 release occurs when the assignee initiates that removal, and 1530 transfer occurs when either revocation or release is coupled with 1531 immediate reassignment. It may be useful to specify procedures 1532 for each of these, or to explicitly prohibit combinations that are 1533 not desired. 1535 9.5. Contact Person vs Assignee or Owner 1536 Many registries include designation of a technical or administrative 1537 contact associated with each entry. Often, this is recorded as 1538 contact information for an individual. It is unclear, though, what 1539 role the individual has with respect to the registration: is this 1540 item registered on behalf of the individual, the company the 1541 individual worked for, or perhaps another organization the individual 1542 was acting for? 1544 This matters because some time later, when the individual has changed 1545 jobs or roles, and perhaps can no longer be contacted, someone might 1546 want to update the registration. IANA has no way to know what 1547 company, organization, or individual should be allowed to take the 1548 registration over. For registrations rooted in RFCs, the stream 1549 owner (such as the IESG or the IAB) can make an overriding decision. 1550 But in other cases, there is no recourse. 1552 Registries can include, in addition to a "Contact" field, an 1553 "Assignee" or "Owner" field (also referred to as "Change Controller") 1554 that can be used to address this situation, giving IANA clear 1555 guidance as to the actual owner of the registration. This is 1556 strongly advised especially for registries that do not require RFCs 1557 to manage their information (registries with policies such as First 1558 Come First Served Section 4.4, Expert Review Section 4.5, and 1559 Specification Required Section 4.6). Alternatively, organizations 1560 can put an organizational role into the "Contact" field in order to 1561 make their ownership clear. 1563 9.6. Closing or Obsoleting a Registry/Registrations 1565 Sometimes there is a request to "close" a registry to further 1566 registrations. When a registry is closed, no further registrations 1567 will be accepted. The information in the registry will still be 1568 valid and registrations already in the registry can still be updated. 1570 A closed registry can also be marked as "obsolete", as an indication 1571 that the information in the registry is no longer in current use. 1573 Specific entries in a registry can be marked as "obsolete" (no longer 1574 in use) or "deprecated" (use is not recommended). 1576 Such changes to registries and registered values are subject to 1577 normal change controls (see Section 2.3). Any closure, obsolescence, 1578 or deprecation serves to annotate the registry involved; the 1579 information in the registry remains there for informational and 1580 historic purposes. 1582 10. Appeals 1584 Appeals of protocol parameter registration decisions can be made 1585 using the normal IETF appeals process as described in [RFC2026], 1586 Section 6.5. That is, an initial appeal should be directed to the 1587 IESG, followed (if necessary) by an appeal to the IAB. 1589 11. Mailing Lists 1591 All IETF mailing lists associated with evaluating or discussing 1592 assignment requests as described in this document are subject to 1593 whatever rules of conduct and methods of list management are 1594 currently defined by Best Current Practices or by IESG decision. 1596 12. Security Considerations 1598 Information that creates or updates a registration needs to be 1599 authenticated and authorized. IANA updates registries according to 1600 instructions in published RFCs and from the IESG. It also may accept 1601 clarifications from document authors, relevant working group chairs, 1602 Designated Experts, and mail list participants, too. 1604 Information concerning possible security vulnerabilities of a 1605 protocol may change over time. Likewise, security vulnerabilities 1606 related to how an assigned number is used may change as well. As new 1607 vulnerabilities are discovered, information about such 1608 vulnerabilities may need to be attached to existing registrations, so 1609 that users are not misled as to the true security issues surrounding 1610 the use of a registered number. 1612 Security needs to be considered as part of the selection of a 1613 registration policy. For some protocols, registration of certain 1614 parameters will have security implications, and registration policies 1615 for the relevant registries must ensure that requests get appropriate 1616 review with those security implications in mind. 1618 An analysis of security issues is generally required for all 1619 protocols that make use of parameters (data types, operation codes, 1620 keywords, etc.) used in IETF protocols or registered by IANA. Such 1621 security considerations are usually included in the protocol document 1622 [RFC3552]. It is the responsibility of the IANA considerations 1623 associated with a particular registry to specify whether value- 1624 specific security considerations must be provided when assigning new 1625 values, and the process for reviewing such claims. 1627 13. IANA Considerations 1629 IANA is asked to update any references to RFC 5226 to now point to 1630 this document. 1632 14. Changes Relative to Earlier Editions of BCP 26 1634 14.1. 2016: Changes in This Document Relative to RFC 5226 1636 Significant additions: 1638 o Removed RFC 2119 key words, boilerplate, and reference, preferring 1639 plain English -- this is not a protocol specification. 1641 o Added Section 1.1, Keep IANA Considerations for IANA 1642 o Added Section 1.2, For More Information 1644 o Added Section 2.1, Hierarchical Registry Structure 1646 o Added best practice for selecting an appropriate policy into 1647 Section 4. 1649 o Added Section 4.12, Using Multiple Policies in Combination. 1651 o Added Section 2.3, Specifying Change Control for a Registry 1653 o Added Section 3.4, Early Allocations 1655 o Moved well-known policies into a separate section for each, 1656 subsections of Section 4. 1658 o Added Section 5.4, Expert Reviews and the Document Lifecycle 1660 o Added Section 7, Documentation References in IANA Registries 1662 o Added Section 8, What to Do in "bis" Documents 1664 o Added Section 9.5, Contact Person vs Assignee or Owner 1666 o Added Section 9.6, Closing or Obsoleting a Registry 1668 Clarifications and such: 1670 o Some reorganization -- moved text around for clarity and easier 1671 reading. 1673 o Made clarifications about identification of IANA registries and 1674 use of URLs for them. 1676 o Clarified the distinction between "Unassigned" and "Reserved". 1678 o Made some clarifications in "Expert Review" about instructions to 1679 the designated expert. 1681 o Made some clarifications in "Specification Required" about how to 1682 declare this policy. 1684 o Assorted minor clarifications and editorial changes throughout. 1686 14.2. 2008: Changes in RFC 5226 Relative to RFC 2434 1688 Changes include: 1690 o Major reordering of text to expand descriptions and to better 1691 group topics such as "updating registries" vs. "creating new 1692 registries", in order to make it easier for authors to find the 1693 text most applicable to their needs. 1695 o Numerous editorial changes to improve readability. 1697 o Changed the term "IETF Consensus" to "IETF Review" and added more 1698 clarifications. History has shown that people see the words "IETF 1699 Consensus" (without consulting the actual definition) and are 1700 quick to make incorrect assumptions about what the term means in 1701 the context of IANA Considerations. 1703 o Added "RFC Required" to list of defined policies. 1705 o Much more explicit directions and examples of "what to put in 1706 RFCs". 1708 o "Specification Required" now implies use of a Designated Expert to 1709 evaluate specs for sufficient clarity. 1711 o Significantly changed the wording in the Designated Experts 1712 section. Main purpose is to make clear that Expert Reviewers are 1713 accountable to the community, and to provide some guidance for 1714 review criteria in the default case. 1716 o Changed wording to remove any special appeals path. The normal 1717 RFC 2026 appeals path is used. 1719 o Added a section about reclaiming unused values. 1721 o Added a section on after-the-fact registrations. 1723 o Added a section indicating that mailing lists used to evaluate 1724 possible assignments (such as by a Designated Expert) are subject 1725 to normal IETF rules. 1727 15. Acknowledgments 1729 15.1. Acknowledgments for This Document (2016) 1731 Thomas Narten and Harald Tveit Alvestrand edited the two earlier 1732 editions of this document (RFCs 2434 and 5226), and Thomas continues 1733 his role in this third edition. Much of the text from RFC 5226 1734 remains in this edition. 1736 Thank you to Amanda Baber and Pearl Liang for their multiple reviews 1737 and suggestions for making this document as thorough as possible. 1739 This document has benefited from thorough review and comments by Tony 1740 Hansen, John Klensin, and Mark Nottingham. 1742 Special thanks to Mark Nottingham for reorganizing some of the text 1743 for better organization and readability, and to Tony Hansen for 1744 acting as document shepherd. 1746 15.2. Acknowledgments from the second edition (2008) 1747 The original acknowledgments section in RFC 5226 was: 1749 This document has benefited from specific feedback from Jari Arkko, 1750 Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Spencer 1751 Dawkins, Barbara Denny, Miguel Garcia, Paul Hoffman, Russ Housley, 1752 John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus 1753 Westerlund, and Bert Wijnen. 1755 15.3. Acknowledgments from the first edition (1998) 1757 The original acknowledgments section in RFC 2434 was: 1759 Jon Postel and Joyce Reynolds provided a detailed explanation on what 1760 IANA needs in order to manage assignments efficiently, and patiently 1761 provided comments on multiple versions of this document. Brian 1762 Carpenter provided helpful comments on earlier versions of the 1763 document. One paragraph in the Security Considerations section was 1764 borrowed from RFC 4288. 1766 16. References 1768 16.1. Normative References 1770 [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 1771 3", BCP 9, RFC 2026, October 1996. 1773 16.2. Informative References 1775 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1776 1981. 1778 [RFC1591] Postel, J., "Domain Name System Structure and Delegation", 1779 RFC 1591, DOI 10.17487/RFC1591, March 1994, . 1782 [RFC2860] Carpenter, B., Baker, F. and M. Roberts, "Memorandum of 1783 Understanding Concerning the Technical Work of the 1784 Internet Assigned Numbers Authority", RFC 2860, June 2000. 1786 [RFC2939] Droms, R., "Procedures and IANA Guidelines for Definition 1787 of New DHCP Options and Message Types", BCP 43, RFC 2939, 1788 September 2000. 1790 [RFC3228] Fenner, B., "IANA Considerations for IPv4 Internet Group 1791 Management Protocol (IGMP)", BCP 57, RFC 3228, February 1792 2002. 1794 [RFC3406] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, 1795 "Uniform Resource Names (URN) Namespace Definition 1796 Mechanisms", BCP 66, RFC 3406, DOI 10.17487/RFC3406, 1797 October 2002, . 1799 [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC 1800 Text on Security Considerations", BCP 72, RFC 3552, July 1801 2003. 1803 [RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote 1804 Authentication Dial In User Service)", RFC 3575, July 1805 2003. 1807 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1808 Considered Useful", BCP 82, RFC 3692, January 2004. 1810 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J. and H. 1811 Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 1812 3748, June 2004. 1814 [RFC3942] Volz, B., "Reclassifying Dynamic Host Configuration 1815 Protocol version 4 (DHCPv4) Options", RFC 3942, November 1816 2004. 1818 [RFC3968] Camarillo, G., "The Internet Assigned Number Authority 1819 (IANA) Header Field Parameter Registry for the Session 1820 Initiation Protocol (SIP)", BCP 98, RFC 3968, December 1821 2004. 1823 [RFC4005] Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter 1824 Network Access Server Application", RFC 4005, August 2005. 1826 [RFC4025] Richardson, M., "A Method for Storing IPsec Keying 1827 Material in DNS", RFC 4025, March 2005. 1829 [RFC4044] McCloghrie, K., "Fibre Channel Management MIB", RFC 4044, 1830 May 2005. 1832 [RFC4124] Le Faucheur, F., "Protocol Extensions for Support of 1833 Diffserv-aware MPLS Traffic Engineering", RFC 4124, June 1834 2005. 1836 [RFC4169] Torvinen, V., Arkko, J. and M. Naslund, "Hypertext 1837 Transfer Protocol (HTTP) Digest Authentication Using 1838 Authentication and Key Agreement (AKA) Version-2", RFC 1839 4169, November 2005. 1841 [RFC4271] Rekhter, Y., Li, T. and S. Hares, "A Border Gateway 1842 Protocol 4 (BGP-4)", RFC 4271, January 2006. 1844 [RFC4283] Patel, A., Leung, K., Khalil, M., Akhtar, H. and K. 1845 Chowdhury, "Mobile Node Identifier Option for Mobile IPv6 1846 (MIPv6)", RFC 4283, November 2005. 1848 [RFC4340] Kohler, E., Handley, M. and S. Floyd, "Datagram Congestion 1849 Control Protocol (DCCP)", RFC 4340, March 2006. 1851 [RFC4395] Hansen, T., Hardie, T. and L. Masinter, "Guidelines and 1852 Registration Procedures for New URI Schemes", BCP 35, RFC 1853 4395, February 2006. 1855 [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and 1856 Security Layer (SASL)", RFC 4422, June 2006. 1858 [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge 1859 Emulation (PWE3)", BCP 116, RFC 4446, April 2006. 1861 [RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) 1862 Considerations for the Lightweight Directory Access 1863 Protocol (LDAP)", BCP 64, RFC 4520, June 2006. 1865 [RFC4589] Schulzrinne, H. and H. Tschofenig, "Location Types 1866 Registry", RFC 4589, July 2006. 1868 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 1869 ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006. 1871 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1872 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 1874 [RFC5378] Bradner, S. and J. Contreras, "Rights Contributors Provide 1875 to the IETF Trust", BCP 78, RFC 5378, November 2008. 1877 [RFC5742] Alvestrand, H. and R. Housley, "IESG Procedures for 1878 Handling of Independent and IRTF Stream Submissions", BCP 1879 92, RFC 5742, December 2009. 1881 [RFC5771] Cotton, M., Vegoda, L. and D. Meyer, "IANA Guidelines for 1882 IPv4 Multicast Address Assignments", BCP 51, RFC 5771, 1883 March 2010. 1885 [RFC5795] Sandlund, K., Pelletier, G. and L-E. Jonsson, "The RObust 1886 Header Compression (ROHC) Framework", RFC 5795, March 1887 2010. 1889 [RFC6195] Eastlake, D., "Domain Name System (DNS) IANA 1890 Considerations", BCP 42, RFC 6195, March 2011. 1892 [RFC6275] Perkins, C., Johnson, D. and J. Arkko, "Mobility Support 1893 in IPv6", RFC 6275, July 2011. 1895 [RFC6709] Carpenter, B., Aboba, B. and S. Cheshire, "Design 1896 Considerations for Protocol Extensions", RFC 6709, 1897 September 2012. 1899 [RFC6838] Freed, N., Klensin, J. and T. Hansen, "Media Type 1900 Specifications and Registration Procedures", BCP 13, RFC 1901 6838, DOI 10.17487/RFC6838, January 2013, . 1904 [RFC6994] Touch, J., "Shared Use of Experimental TCP Options", RFC 1905 6994, DOI 10.17487/RFC6994, August 2013, . 1908 [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code 1909 Points", BCP 100, RFC 7120, January 2014. 1911 [RFC7564] Saint-Andre, P. and M. Blanchet, "PRECIS Framework: 1912 Preparation, Enforcement, and Comparison of 1913 Internationalized Strings in Application Protocols", RFC 1914 7564, DOI 10.17487/RFC7564, May 2015, . 1917 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A. and 1918 S. Ray, "North-Bound Distribution of Link-State and 1919 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1920 DOI 10.17487/RFC7752, March 2016, . 1923 Authors' Addresses 1925 Michelle Cotton 1926 Internet Corporation for Assigned Names and Numbers 1927 12025 Waterfront Drive, Suite 300 1928 Los Angeles, CA 90094-2536 1929 US 1931 Phone: +1 310 823 9358 1932 Email: michelle.cotton@icann.org 1933 URI: https://www.icann.org/ 1935 Barry Leiba 1936 Huawei Technologies 1938 Phone: +1 646 827 0648 1939 Email: barryleiba@computer.org 1940 URI: http://internetmessagingtechnology.org/ 1942 Thomas Narten 1943 IBM Corporation 1944 3039 Cornwallis Ave., PO Box 12195 - BRQA/502 1945 Research Triangle Park, NC 27709-2195 1946 US 1948 Phone: +1 919 254 7798 1949 Email: narten@us.ibm.com