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'RFC8174') ** Downref: Normative reference to an Unknown state RFC: RFC 952 Summary: 9 errors (**), 0 flaws (~~), 2 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 dnsop D. Crocker 3 Internet-Draft Brandenburg InternetWorking 4 Intended status: Standards Track October 10, 2018 5 Expires: April 13, 2019 7 DNS Scoped Data Through "Underscore" Naming of Attribute Leaves 8 draft-ietf-dnsop-attrleaf-14 10 Abstract 12 Formally, any DNS resource record may occur under any domain name. 13 However some services use an operational convention for defining 14 specific interpretations of an RRset, by locating the records in a 15 DNS branch, under the parent domain to which the RRset actually 16 applies. The top of this subordinate branch is defined by a naming 17 convention that uses a reserved node name, which begins with an 18 _underscore. The underscored naming construct defines a semantic 19 scope for DNS record types that are associated with the parent 20 domain, above the underscored branch. This specification explores 21 the nature of this DNS usage and defines the "DNS Global Underscore 22 Scoped Entry Registry" with IANA. The purpose of the Underscore 23 registry is to avoid collisions resulting from the use of the same 24 underscore-based name, for different services. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on April 13, 2019. 43 Copyright Notice 45 Copyright (c) 2018 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Underscore Scoping . . . . . . . . . . . . . . . . . . . 3 62 1.2. Scaling Benefits . . . . . . . . . . . . . . . . . . . . 4 63 1.3. "Global" Underscored Node Names . . . . . . . . . . . . . 4 64 1.4. Interaction with DNS wildcards . . . . . . . . . . . . . 5 65 2. DNS Underscore Scoped Entry Registries Function . . . . . . . 5 66 3. RRset Use Registration Template . . . . . . . . . . . . . . . 6 67 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 68 4.1. DNS Underscore Global Scoped Entry Registry . . . . . . . 7 69 4.2. DNS Underscore Global Scoped Entry Registry Definition . 8 70 4.3. Initial entries . . . . . . . . . . . . . . . . . . . . . 8 71 5. Guidance for Expert Review . . . . . . . . . . . . . . . . . 9 72 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 73 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 74 7.1. Normative References . . . . . . . . . . . . . . . . . . 10 75 7.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 12 76 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 13 77 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 79 1. Introduction 81 The core Domain Name System (DNS) technical specifications assign no 82 semantics to domain names or their parts, and no constraints upon 83 which resource record (RR) types are permitted to be stored under 84 particular names [RFC1035], [RFC2181]. Over time, some leaf node 85 names, such as "www" and "ftp" have come to imply support for 86 particular services, but this is a matter of operational convention, 87 rather than defined protocol semantics. This freedom in the basic 88 technology has permitted a wide range of administrative and semantic 89 policies to be used -- in parallel. DNS data semantics have been 90 limited to the specification of particular resource record types, on 91 the expectation that new resource record types would be added as 92 needed. Unfortunately, the addition of new resource record types has 93 proven extremely challenging, over the life of the DNS, with 94 significant adoption and use barriers. 96 1.1. Underscore Scoping 98 As an alternative to defining a new RR type, some DNS service 99 enhancements call for using an existing resource record type, but 100 specify a restricted scope for its occurrence. Scope is meant as a 101 static property, not one dependent on the nature of the query. It is 102 an artifact of the DNS name. That scope is a leaf node, within which 103 the uses of specific resource record sets can be formally defined and 104 constrained. The leaf occurs in a branch having a distinguished 105 naming convention: At the top of the branch -- beneath the parent 106 domain name to which the scope applies -- one or more reserved DNS 107 node names begin with an underscore ("_"). Because the DNS rules for 108 a "host" (host name) do not allow use of the underscore character, 109 this distinguishes the underscored name from all legal host names 110 [RFC952]. Effectively, this convention for leaf node naming creates 111 a space for the listing of "attributes" -- in the form of resource 112 record types -- that are associated with the parent domain, above the 113 underscored sub-branch. 115 The scoping feature is particularly useful when generalized resource 116 record types are used -- notably "TXT", "SRV", and "URI" [RFC1035], 117 [RFC2782], [RFC6335], [RFC7553]. It provides efficient separation of 118 one use of them from others. Absent this separation, an 119 undifferentiated mass of these "RRsets" is returned to the DNS 120 client, which then must parse through the internals of the records in 121 the hope of finding ones that are relevant. Worse, in some cases the 122 results are ambiguous because a record type might not adequately 123 self-identify its specific purpose. With underscore-based scoping, 124 only the relevant "RRsets"s are returned. 126 A simple example is DKIM [RFC6376] , which uses "_domainkey" for 127 defining a place to hold a "TXT" record containing signing 128 information for the parent domain. 130 This specification formally defines how underscored labels are used 131 as "attribute" enhancements for their parent domain names. For 132 example, domain name "_domainkey.example." acts as an attribute of 133 the parent domain name "example." To avoid collisions resulting from 134 the use of the same underscore-based labels for different 135 applications using the same resource record type, this document 136 establishes the DNS Underscore Global Scoped Entry IANA Registry. 137 Use of such node names, which begin with underscore, are reserved 138 when they are the underscored name closest to the DNS root; they are 139 considered "global". Underscore-based names that are farther down 140 the hierarchy are handled within the scope of the global underscore 141 name. 143 Discussion Venue: Discussion about this draft should be directed 144 to the dnsop@ietf.org [1] mailing list. 146 NOTE TO RFC EDITOR: Please remove "Discussion Venue" paragraph 147 prior to publication. 149 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 150 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 151 "OPTIONAL" in this document are to be interpreted as described in BCP 152 14 [RFC2119] [RFC8174] when, and only when, they appear in all 153 capitals, as shown here. 155 1.2. Scaling Benefits 157 Some resource record types are used in a fashion that can create 158 scaling problems, if an entire RRset associated with a domain name is 159 aggregated in the leaf node for that name. An increasingly-popular 160 approach, with excellent scaling properties, places the RRset under a 161 specially named branch, which is in turn under the node name that 162 would otherwise contain the RRset. The rules for naming that branch 163 define the context for interpreting the RRset. That is, rather than: 165 domain-name.example 166 / 167 RRset 169 the arrangement is: 171 _branch.domain-name.example 172 / 173 RRset 175 A direct lookup to the subordinate leaf node produces only the 176 desired record types, at no greater cost than a typical DNS lookup. 178 1.3. "Global" Underscored Node Names 180 As defined in [RFC1034] the DNS uses names organized in a tree- 181 structured, or hierarchical fashion. A domain name might have 182 multiple node names that begin with an _underscore. A "global" 183 underscored node name is the one that is closest to the root of the 184 DNS hierarchy, also called the highest-level or top-most. In the 185 presentation convention described in Section 3.1 of [RFC1034] this is 186 the right-most name beginning with an underscore. In other 187 presentation environments it might be positioned differently. To 188 avoid concern for the presentation variations, the qualifier "global" 189 is used here. 191 1.4. Interaction with DNS wildcards 193 DNS wildcards interact poorly with underscored names in two ways. 194 Since wildcards only are interpreted as leaf names, one cannot create 195 the equivalent of a wildcard name for prefixed names. A name such as 196 label.*.example.com is not a wildcard. 198 Conversely, a wildcard such as *.example.com can match any name 199 including an underscored name. So, a wildcard might match an 200 underscored name, returning a record that is the type controlled by 201 the underscored name but is not intended to be used in the 202 underscored context and does not conform to its rules. 204 2. DNS Underscore Scoped Entry Registries Function 206 A registry for "global" DNS node names that begin with an underscore 207 is defined here. The purpose of the Underscore Global Registry is to 208 avoid collisions resulting from the use of the same underscore-based 209 name, for different applications. 211 o If a public specification calls for use of an underscore-prefixed 212 domain node name, the "global" underscored name -- the underscored 213 name that is closest to the DNS root -- MUST be entered into this 214 registry. 216 An underscored name defines the scope of use for specific resource 217 record types, which are associated with the domain name that is the 218 "parent" to the branch defined by the underscored name. A given name 219 defines a specific, constrained context for one or more RR types, 220 where use of such record types conforms to the defined constraints. 222 o Within an underscore scoped leaf, other RRsets that are not 223 specified as part of the scope MAY be used. 225 Structurally, the registry is defined as a single, flat table of RR 226 types, under node names beginning with underscore. In some cases, 227 such as for use of an "SRV" record, the full scoping name might be 228 multi-part, as a sequence of underscored names. Semantically, that 229 sequence represents a hierarchical model and it is theoretically 230 reasonable to allow re-use of a subordinate underscored name in a 231 different, global underscored context; that is, a subordinate name is 232 meaningful only within the scope of the global underscored name. 233 Therefore they are ignored by this DNS Underscore Global Scoped Entry 234 Registry. This registry is for the definition of highest-level -- 235 ie, global -- underscored node name used. 237 +----------------------------+ 238 | NAME | 239 +----------------------------+ 240 | _service1 | 241 | _protoB._service2 | 242 | _protoB._service3 | 243 | _protoC._service3 | 244 | _useX._protoD._service4 | 245 | _protoE._region._authority | 246 +----------------------------+ 248 Table 1: Examples of Underscored Names 250 Only global underscored names are registered in the IANA Underscore 251 Global table. (From the example, that would mean registering 252 _service1, _service2, _service3, _service 4, and _authority.) 254 o The use of underscored node names is specific to each RRTYPE that 255 is being scoped. Each name defines a place, but does not define 256 the rules for what appears underneath that place, either as 257 additional underscored naming or as a leaf node with resource 258 records. Details for those rules are provided by specifications 259 for individual RRTYPEs. The sections below describe the way that 260 existing underscore labels are used with the RRTYPEs that they 261 name. 263 o Definition and registration of subordinate, underscore node names 264 is the responsibility of the specification that creates the global 265 registry entry. 267 That is, if a scheme using a global underscore node name has one or 268 more subordinate levels of underscore node naming, the namespaces 269 from which names for those lower levels are chosen are controlled by 270 the parent underscore node name. Each globally-registered underscore 271 name owns a distinct, subordinate name space. 273 3. RRset Use Registration Template 275 This section provides a basic template that can be used to register 276 new entries in the IANA DNS Underscore Global Scoped Entry Registry, 277 if the global underscored name above the RRTYPE is not already 278 registered. The text can be added to specifications using 279 RRTYPE/_Node-name combinations that have not already been registered. 281 "Per {RFC Attrleaf} please add the following entry to the DNS 282 Underscore Global Scoped Entry Registry:" 284 Note to RFC Editor: Please replace the above "{RFC Attrleaf}" text 285 with a reference to this document's RFC number. /d 287 +----------+-------------------+------------------------------------+ 288 | RR Type | _NODE NAME | REFERENCE | 289 +----------+-------------------+------------------------------------+ 290 | {RRTYPE} | _{DNS global node | {citation for the document making | 291 | | name} | the addition.} | 292 +----------+-------------------+------------------------------------+ 294 Table 2: Underscore Global Registry Entry 296 4. IANA Considerations 298 Per [RFC8126], IANA is requested to establish the: 300 DNS Underscore Global Scoped Entry Registry 302 This section describes actions requested of IANA. The guidance in 303 [IANA] is used. 305 4.1. DNS Underscore Global Scoped Entry Registry 307 The DNS Global Underscore Scoped Entry Registry is any DNS node name 308 that begin with the underscore character ("_", ASCII 0x5F) and is the 309 underscored node name closest to the root; that is it defines the 310 highest-level of a DNS branch, under a "parent" domain name. 312 o This registry is to operate under the IANA rules for "Expert 313 Review" registration; see Section 5. 315 o The contents of each entry in the Global registry are defined in 316 Section 4.2. 318 o Each entry in the registry MUST contain values for all of the 319 fields specified in Section 4.2. 321 o Within the registry, the combination of RR Type and _Node Name 322 MUST be unique. 324 o The table is to be maintained with entries sorted by the first 325 column (RR Type) and, within that, the second column (_Node Name). 327 o The required Reference for an entry MUST have a stable resolution 328 to the organization controlling that registry entry. 330 4.2. DNS Underscore Global Scoped Entry Registry Definition 332 A registry entry contains: 334 RR Type: Lists an RR type that is defined for use within this 335 scope 337 _Node Name: Specifies a single, underscored name that defines a 338 reserved name; this name is the "global" entry name for the 339 scoped resource record types that are associated with that 340 name; for characters in the name that have an upper-case 341 form and a lower-case form, the character MUST be recorded 342 as lower-case, to simplify name comparisons. 344 References: Lists specification that defines a record type and its 345 use under this Name. The organization producing the 346 specification retains control over the registry entry for 347 the _Node Name 349 Each RR type that is to be used MUST have a separate registry entry. 351 4.3. Initial entries 353 Initial entries in the registry are: 355 +------------+------------------+------------+ 356 | RR Type | _NODE NAME | REFERENCE | 357 +------------+------------------+------------+ 358 | NULL | _ta-* {see note} | [RFC8145] | 359 | OPENPGPKEY | _openpgpkey | [RFC7929] | 360 | PTR | _tcp | [RFC6763] | 361 | PTR | _udp | [RFC6763] | 362 | SMIMEA | _smimecert | [RFC8162] | 363 | SRV | _dccp | [RFC2782] | 364 | SRV | _ipv6 | [RFC5026] | 365 | SRV | _sip | [RFC5509] | 366 | SRV | _sctp | [RFC2782] | 367 | SRV | _tcp | [RFC2782] | 368 | SRV | _udp | [RFC2782] | 369 | SRV | _xmpp | [RFC3921] | 370 | TLSA | _dane | [RFC7671] | 371 | TLSA | _sctp | [RFC6698] | 372 | TLSA | _tcp | [RFC6698] | 373 | TLSA | _udp | [RFC6698] | 374 | TXT | _mta-sts | [MTA-STS] | 375 | TXT | _acme-challenge | [ACME] | 376 | TXT | _dmarc | [RFC7489] | 377 | TXT | _domainkey | [RFC6376] | 378 | TXT | _spf | [RFC7208] | 379 | TXT | _vouch | [RFC5518] | 380 | URI | _iax | [RFC6315] | 381 | URI | _acct | [RFC7566] | 382 | URI | _dccp | [RFC6118] | 383 | URI | _email | [RFC6118] | 384 | URI | _ems | [RFC6118] | 385 | URI | _fax | [RFC6118] | 386 | URI | _ft | [RFC6118] | 387 | URI | _h323 | [RFC6118] | 388 | URI | _ical-sched | [RFC6118] | 389 | URI | _ical-access | [RFC6118] | 390 | URI | _ifax | [RFC6118] | 391 | URI | _im | [RFC6118] | 392 | URI | _mms | [RFC6118] | 393 | URI | _pres | [RFC6118] | 394 | URI | _pstn | [RFC7553] | 395 | URI | _sctp | [RFC7553] | 396 | URI | _sip | [RFC7553] | 397 | URI | _sms | [RFC6118] | 398 | URI | _tcp | [RFC6118] | 399 | URI | _udp | [RFC6118] | 400 | URI | _unifmsg | [RFC6118] | 401 | URI | _vcard | [RFC6118] | 402 | URI | _videomsg | [RFC6118] | 403 | URI | _voice | [RFC6118] | 404 | URI | _voicemsg | [RFC6118] | 405 | URI | _vpim | [RFC6118] | 406 | URI | _web | [RFC6118] | 407 | URI | _xmpp | [RFC6118] | 408 +------------+------------------+------------+ 410 Table 3: Underscore Global Registry (initial entries) 412 NOTE: Under the NULL RR, the entry "_ta-*" is meant to denote all 413 node names beginning with the string "_ta-". It does NOT refer to 414 a DNS wildcard specification. 416 5. Guidance for Expert Review 418 This section provides guidance for expert review of registration 419 requests in the DNS Underscore Global Scoped Entry Registry. 421 This review is solely to determine adequacy of a requested entry 422 in this Registry, and does not include review of other aspects of 423 the document specifying that entry. For example such a document 424 might also contain a definition of the resource record type that 425 is referenced by the requested entry. Any required review of that 426 definition is separate from the expert review required here. 428 The review is for the purposes of ensuring that: 430 o The details for creating the registry entry are sufficiently 431 clear, precise and complete 433 o The combination of the underscored name, under which the listed 434 resource record type is used, and the resource record type, is 435 unique in the table 437 For the purposes of this Expert Review, other matters of the 438 specification's technical quality, adequacy or the like are outside 439 of scope. 441 6. Security Considerations 443 This memo raises no security issues. 445 7. References 447 7.1. Normative References 449 [ACME] Barnes, R., Hoffman-Andrews, J., McCarney, D., and J. 450 Kasten, "Automatic Certificate Management Environment 451 (ACME)", I-D draft-ietf-acme-acme-11, March 2018. 453 [IANA] M. Cotton, B. Leiba, and T. Narten, "Guidelines for 454 Writing an IANA Considerations Section in RFCs", RFC 8126, 455 June 2017. 457 [MTA-STS] Margolis, D., Risher, M., Ramakrishnan, B., Brotman, A., 458 and J. Jones, "SMTP MTA Strict Transport Security (MTA- 459 STS)", I-D draft-ietf-uta-mta-sts. 461 [RFC1034] Mockapetris, P., "Domain Names - Concepts and Facilities", 462 STD 13, RFC 1034, November 1987. 464 [RFC1035] Mockapetris, P., "Domain Names - Implementation and 465 Specification", STD 13, RFC 1035, November 1987. 467 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 468 Requirement Levels", BCP 14, RFC 2119, March 1997. 470 [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS 471 Specification", RFC 2181, July 1997. 473 [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for 474 specifying the location of services (DNS SRV)", RFC 2782, 475 February 2000. 477 [RFC3921] Saint-Andre, P., Ed., "Extensible Messaging and Presence 478 Protocol (XMPP): Instant Messaging and Presence", 479 RFC 3921, DOI 10.17487/RFC3921, October 2004, 480 . 482 [RFC5026] Giaretta, G., Ed., Kempf, J., and V. Devarapalli, Ed., 483 "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026, 484 DOI 10.17487/RFC5026, October 2007, 485 . 487 [RFC5509] Loreto, S., "Internet Assigned Numbers Authority (IANA) 488 Registration of Instant Messaging and Presence DNS SRV RRs 489 for the Session Initiation Protocol (SIP)", RFC 5509, 490 DOI 10.17487/RFC5509, April 2009, 491 . 493 [RFC5518] Hoffman, P., Levine, J., and A. Hathcock, "Vouch By 494 Reference", RFC 5518, April 2009. 496 [RFC6118] Hoeneisen, B. and A. Mayrhofer, "Update of Legacy IANA 497 Registrations of Enumservices", RFC 6118, 498 DOI 10.17487/RFC6118, March 2011, 499 . 501 [RFC6315] Guy, E. and K. Darilion, "IANA Registration for 502 Enumservice 'iax'", RFC 6315, DOI 10.17487/RFC6315, July 503 2011, . 505 [RFC6335] Cotton, M., Eggert, L., Tpuch, J., Westerlund, M., and S. 506 Cheshire, "Internet Assigned Numbers Authority (IANA) 507 Procedures for the Management of the Service Name and 508 Transport Protocol Port Number Registry", RFC 6335, Aug 509 2011. 511 [RFC6376] Crocker, D., Hansen, T., and M. Kucherawy, "DomainKeys 512 Identified Mail (DKIM) Signatures", RFC 6376, Sept 2011. 514 [RFC6698] Hoffman, J. and J. Schlyter, "The DNS-Based Authentication 515 of Named Entities (DANE) Transport Layer Security (TLS) 516 Protocol: TLSA", RFC 6698, August . 518 [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service 519 Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, 520 . 522 [RFC7208] Kitterman, S., "Sender Policy Framework (SPF) for 523 Authorizing Use of Domains in E-Mail, Version 1", 524 RFC 7208, April 2014. 526 [RFC7489] Kucherawy, M., Ed. and E. Zwicky, Ed., "Domain-based 527 Message Authentication, Reporting, and Conformance 528 (DMARC)", RFC 7489, March 2015. 530 [RFC7553] Falstrom, P. and O. Kolkman, "The Uniform Resource 531 Identifier (URI) DNS Resource Record", RFC 7553, 532 ISSN 2070-1721, June 2015. 534 [RFC7566] Goix, L. and K. Li, "Enumservice Registration for 'acct' 535 URI", RFC 7566, DOI 10.17487/RFC7566, June 2015, 536 . 538 [RFC7671] Dukhovni, V. and W. Hardaker, "The DNS-Based 539 Authentication of Named Entities (DANE) Protocol: Updates 540 and Operational Guidance", RFC 7671, DOI 10.17487/RFC7671, 541 October 2015, . 543 [RFC7929] Wouters, P., , RFC 7929, August 2016. 545 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 546 Writing an IANA Considerations Section in RFCs", RFC 8126, 547 June 2017. 549 [RFC8145] Wessels, D., Kumari, W., and P. Hoffman, "Signaling Trust 550 Anchor Knowledge in DNS Security Extensions (DNSSEC)", 551 RFC 8145, April 2017. 553 [RFC8162] Hoffman, P. and J. Schlyter, "Using Secure DNS to 554 Associate Certificates with Domain Names for S/MIME", 555 RFC 8162, May 2017. 557 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 558 2119 Key Words", RFC 8162, May 2017. 560 [RFC952] Harrenstien, K., Stahl, M., and E. Feinler, "DOD Internet 561 Host Table Specification", RFC 952, October 1985. 563 7.2. URIs 565 [1] mailto:dnsop@ietf.org 567 Appendix A. Acknowledgements 569 Thanks go to Bill Fenner, Dick Franks, Tony Hansen, Martin Hoffmann, 570 Paul Hoffman, Peter Koch, Olaf Kolkman, Murray Kucherawy, John 571 Levine, and Andrew Sullivan for diligent review of the (much) earlier 572 drafts. For the later enhancements, thanks to: Stephane Bortzmeyer, 573 Alissa Cooper, Bob Harold, Benjamin Kaduk, Mirja Kuehlewind, Warren 574 Kumari, John Levine, Joel Jaeggli, Benno Overeinder, Eric Rescorla, 575 Adam Roach, Petr Špaček, Ondřej Sury, Paul Vixie, Tim 576 Wicinski, and Paul Wouters. 578 Special thanks to Ray Bellis for his persistent encouragement to 579 continue this effort, as well as the suggestion for an essential 580 simplification to the registration model. 582 Author's Address 584 Dave Crocker 585 Brandenburg InternetWorking 586 675 Spruce Dr. 587 Sunnyvale, CA 94086 588 USA 590 Phone: +1.408.246.8253 591 Email: dcrocker@bbiw.net 592 URI: http://bbiw.net/