idnits 2.17.1 draft-ietf-ecrit-requirements-12.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 17. -- Found old boilerplate from RFC 3978, Section 5.5 on line 1088. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1065. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1072. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1078. ** This document has an original RFC 3978 Section 5.4 Copyright Line, instead of the newer IETF Trust Copyright according to RFC 4748. ** This document has an original RFC 3978 Section 5.5 Disclaimer, instead of the newer disclaimer which includes the IETF Trust according to RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (August 26, 2006) is 6453 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: '13' is defined on line 1028, but no explicit reference was found in the text == Outdated reference: A later version (-05) exists of draft-ietf-ecrit-security-threats-03 == Outdated reference: A later version (-07) exists of draft-ietf-ecrit-service-urn-04 == Outdated reference: A later version (-09) exists of draft-ietf-sipping-toip-06 Summary: 3 errors (**), 0 flaws (~~), 7 warnings (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ECRIT H. Schulzrinne 3 Internet-Draft Columbia U. 4 Expires: February 27, 2007 R. Marshall, Ed. 5 TCS 6 August 26, 2006 8 Requirements for Emergency Context Resolution with Internet 9 Technologies 10 draft-ietf-ecrit-requirements-12 12 Status of this Memo 14 By submitting this Internet-Draft, each author represents that any 15 applicable patent or other IPR claims of which he or she is aware 16 have been or will be disclosed, and any of which he or she becomes 17 aware will be disclosed, in accordance with Section 6 of BCP 79. 19 Internet-Drafts are working documents of the Internet Engineering 20 Task Force (IETF), its areas, and its working groups. Note that 21 other groups may also distribute working documents as Internet- 22 Drafts. 24 Internet-Drafts are draft documents valid for a maximum of six months 25 and may be updated, replaced, or obsoleted by other documents at any 26 time. It is inappropriate to use Internet-Drafts as reference 27 material or to cite them other than as "work in progress." 29 The list of current Internet-Drafts can be accessed at 30 http://www.ietf.org/ietf/1id-abstracts.txt. 32 The list of Internet-Draft Shadow Directories can be accessed at 33 http://www.ietf.org/shadow.html. 35 This Internet-Draft will expire on February 27, 2007. 37 Copyright Notice 39 Copyright (C) The Internet Society (2006). 41 Abstract 43 This document defines terminology and enumerates requirements for the 44 context resolution of emergency calls placed by the public using 45 voice-over-IP (VoIP) and general Internet multimedia systems, where 46 Internet protocols are used end-to-end. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Requirements Terminology . . . . . . . . . . . . . . . . . . 5 52 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 6 53 3.1 Emergency Services . . . . . . . . . . . . . . . . . . . . 6 54 3.2 Service Providers . . . . . . . . . . . . . . . . . . . . 6 55 3.3 Actors . . . . . . . . . . . . . . . . . . . . . . . . . . 7 56 3.4 Call Routing Entities . . . . . . . . . . . . . . . . . . 7 57 3.5 Location . . . . . . . . . . . . . . . . . . . . . . . . . 7 58 3.6 Identifiers, Numbers and Dial Strings . . . . . . . . . . 8 59 3.7 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 9 60 4. Basic Actors . . . . . . . . . . . . . . . . . . . . . . . . 11 61 5. High-Level Requirements . . . . . . . . . . . . . . . . . . 13 62 6. Identifying the Caller's Location . . . . . . . . . . . . . 15 63 7. Emergency Service Identifier . . . . . . . . . . . . . . . . 18 64 8. Mapping Protocol . . . . . . . . . . . . . . . . . . . . . . 21 65 9. Security Considerations . . . . . . . . . . . . . . . . . . 26 66 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 27 67 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 28 68 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 29 69 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 70 13.1 Normative References . . . . . . . . . . . . . . . . . . 30 71 13.2 Informative References . . . . . . . . . . . . . . . . . 30 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 31 73 Intellectual Property and Copyright Statements . . . . . . . 32 75 1. Introduction 77 Users of both voice-centric (telephone-like) and non-voice services 78 such as text communication for hearing disabled users (RFC 3351 [3]) 79 expect to be able to initiate a request for help in case of an 80 emergency. 82 Unfortunately, the existing mechanisms to support emergency calls 83 that have evolved within the public circuit-switched telephone 84 network (PSTN) are not appropriate to handle evolving IP-based voice, 85 text and real-time multimedia communications. This document outlines 86 the key requirements that IP-based end systems and network elements, 87 such as Session Initiation Protocol (SIP) [2] proxies, need to 88 satisfy in order to provide emergency call services, which at a 89 minimum, offer the same functionality as existing PSTN services, with 90 the additional overall goal of making emergency calling more robust, 91 less costly to implement, and multimedia-capable. 93 This document only focuses on end-to-end IP-based calls, i.e., where 94 the emergency call originates from an IP end system and terminates in 95 an IP-capable PSAP, conveyed entirely over an IP network. 97 We first define terminology in Section 3. The document then outlines 98 various functional issues which relate to placing an IP-based 99 emergency call, including a description of baseline requirements 100 (Section 5), identification of the emergency caller's location 101 (Section 6), use of a service identifier to declare a call to be an 102 emergency call (Section 7), and finally, the mapping function 103 required to route the call to the appropriate PSAP (Section 8). 105 The primary purpose of the mapping protocol is to produce a PSAP URI 106 drawn from a preferred set of URI schemes such as SIP or SIPS URIs, 107 based on both location information [8] and a service identifier in 108 order to facilitate the IP end-to-end completion of an emergency 109 call. 111 Aside from obtaining a PSAP URI, the mapping protocol is useful for 112 obtaining other information as well. There may be a case, for 113 example, where an appropriate emergency number is not known, only 114 location. The mapping protocol can then return a geographically 115 appropriate emergency number based on the input. 117 Since some PSAPs may not immediately support IP, or because some user 118 equipment (UE) may not initially support emergency service 119 identifiers, it may be necessary to also support emergency service 120 identifiers that utilize less preferred URI schemes, such as a tel 121 URI in order to complete an emergency call via the PSTN. 123 Identification of the caller, while not incompatible with the 124 requirements for messaging outlined within this document, is 125 considered to be outside the scope of this document. 127 Location is required for two separate purposes, first, to support the 128 routing of the emergency call to the appropriate PSAP and second, to 129 display the caller's location to the call taker to help in 130 dispatching emergency assistance to the appropriate location. 132 2. Requirements Terminology 134 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 135 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 136 and "OPTIONAL" are to be interpreted as described in RFC 2119 [1], 137 with the qualification that unless otherwise stated these words apply 138 to the design of the mapping protocol, not its implementation or 139 application. 141 3. Terminology 143 3.1 Emergency Services 145 Basic emergency service: Basic emergency service allows a caller to 146 reach a PSAP serving its current location, but the PSAP may not be 147 able to determine the identity or geographic location of the 148 caller, except by the call taker asking the caller. 150 Enhanced emergency service: In enhanced emergency service, the PSAP 151 call taker can determine the caller's current location. 153 3.2 Service Providers 155 Internet Attachment Provider (IAP): An organization that provides 156 physical and data link (layer 2) network connectivity to its 157 customers or users, e.g., through digital subscriber lines, cable 158 TV plants, Ethernet, leased lines or radio frequencies. Examples 159 of such organizations include telecommunication carriers, 160 municipal utilities, larger enterprises with their own network 161 infrastructure, and government organizations such as the military. 163 Internet Service Provider (ISP): An organization that provides IP 164 network-layer services to its customers or users. This entity may 165 or may not provide the physical-layer and data link (layer-2) 166 connectivity, such as fiber or Ethernet, i.e., it may or may not 167 play the role of an IAP. 169 Application Service Provider (ASP): The organization or entity that 170 provides application-layer services, which may include voice (see 171 "Voice Service Provider"). This entity can be a private 172 individual, an enterprise, a government, or a service provider. 173 An ASP is more general than a Voice Service Provider, since 174 emergency calls may use other media beyond voice, including text 175 and video. For a particular user, the ASP may or may not be the 176 same organization as his IAP or ISP. 178 Voice Service Provider (VSP): A specific type of Application Service 179 Provider which provides voice related services based on IP, such 180 as call routing, a SIP URI, or PSTN termination. In this 181 document, unless noted otherwise, any reference to "Voice Service 182 Provider" or "VSP" may be used interchangeably with "Application/ 183 Voice Service Provider" or "ASP/VSP". 185 3.3 Actors 187 (Emergency) caller: The term "caller" or "emergency caller" refer to 188 the person placing an emergency call or sending an emergency 189 instant message (IM). 191 User Equipment (UE): User equipment is the device or software 192 operated by the caller to place an emergency call. A SIP user 193 agent (UA) is an example of a UE. 195 Call taker: A call taker is an agent at the PSAP that accepts calls 196 and may dispatch emergency help. Sometimes the functions of call 197 taking and dispatching are handled by different groups of people, 198 but these divisions of labor are not generally visible to the 199 caller and thus do not concern us here. 201 3.4 Call Routing Entities 203 Emergency Service Routing Proxy (ESRP): An ESRP is an emergency call 204 routing support entity that invokes the location-to-PSAP URI 205 mapping, to return either the URI for the appropriate PSAP, or the 206 URI for another ESRP. (In a SIP system, the ESRP would typically 207 be a SIP proxy, but may also be a back-to-back user agent 208 (B2BUA)). 210 Public Safety Answering Point (PSAP): Physical location where 211 emergency calls are received under the responsibility of a public 212 authority. (This terminology is used by both ETSI, in ETSI SR 002 213 180, and NENA.) In the United Kingdom, PSAPs are called Operator 214 Assistance Centres, in New Zealand, Communications Centres. 215 Within this document, it is assumed, unless stated otherwise, that 216 PSAPs support the receipt of emergency calls over IP, using 217 appropriate application layer protocols such as SIP for call 218 signaling and RTP for media. 220 3.5 Location 222 Location: A geographic identification assigned to a region or feature 223 based on a specific coordinate system, or by other precise 224 information such as a street number and name. It can be either a 225 civic or geographic location. 227 Civic location: A described location based on some reference system, 228 such as jurisdictional region or postal delivery grid. A street 229 address is a common example of a civic location. 231 Geographic location: A reference to a point which is able to be 232 located as described by a set of defined coordinates within a 233 geographic coordinate system, such as latitude and longitude 234 within the WGS-84 datum. For example, 2-D geographic location is 235 defined as an (x,y) coordinate value pair according to the 236 distance north or south of the equator and east or west of the 237 prime meridian. 239 Location validation: A caller location is considered valid if the 240 civic or geographic location is recognizable within an acceptable 241 location reference system (e.g., United States Postal Address or 242 the WGS-84 datum) and can be mapped to one or more PSAPs. While 243 it is desirable to determine that a location exists, validation 244 may not ensure that such a location exists, but rather may only 245 ensure that the location falls within some range of known values. 246 Location validation ensures that a location is able to be 247 referenced for mapping, but makes no assumption about the 248 association between the caller and the caller's location. 250 3.6 Identifiers, Numbers and Dial Strings 252 (Emergency) service number: The (emergency) service number is a 253 string of digits used to reach the (emergency) service. The 254 emergency service number is often just called the emergency 255 number. It is the number typically dialed on devices directly 256 connected to the PSTN and the number reserved for emergency calls 257 by national or regional numbering authorities. It only contains 258 the digits 0 through 9, # and *. The service number may depend on 259 the location of the caller. For example, the general emergency 260 service number in the United States is 911 and the poison control 261 service number is 18002221222. In most cases, the service number 262 and dial string are the same; they may differ in some private 263 phone networks. A service number may be carried in tel URLs [6], 264 along with a context identifier. In the North American numbering 265 plan, some service numbers are also three-digit N11 or service 266 codes, but not all emergency numbers have three digits. A caller 267 may have to dial a service dial string (below) that differs from 268 the service number when using a PBX. 270 (Emergency) service dial string: The service dial string identifies 271 the string of digits that a caller must dial to reach a particular 272 (emergency) service. In devices directly connected to the PSTN, 273 the service dial string is the same as the service number and may 274 thus depend on the location of the caller. However, in private 275 phone networks, such as in PBXs, the service dial string consists 276 of a dialing prefix to reach an outside line, followed by the 277 emergency number. For example, in a hotel, the dial string for 278 emergency services in the United States might be 9911. Dial 279 strings may contain indications of pauses or wait-for-secondary- 280 dial-tone indications. Service dial strings are outside the scope 281 of this document. 283 (Emergency) service identifier: The (emergency) service identifier 284 describes the emergency service, independent of the user interface 285 mechanism, the signaling protocol that is used to reach the 286 service, or the caller's geographic location. It is a protocol 287 constant and used within the mapping and signaling protocols. An 288 example is the service URN [11]. 290 (Emergency) service URL: The service URL is a protocol-specific 291 (e.g., SIP) or protocol-agnostic (e.g., im: [5]) contains the 292 address of the PSAP or other emergency service. It depends on the 293 specific signaling or data transport protocol used to reach the 294 emergency service. 296 Service URN: A service URN is an implementation of a service 297 identifier, which can be applied to both emergency and non- 298 emergency contexts, e.g., urn:service:sos or 299 urn:service:counseling. Within this document, service URNs are 300 referred to as 'emergency service URNs' [11]. 302 Home emergency number: A home emergency number is the emergency 303 number valid at the caller's customary home location, e.g., his 304 permanent residence. The home location may or may not coincide 305 with the service area of the caller's VSP. 307 Home emergency dial string: A home dial string is the dial string 308 valid at the caller's customary home location, e.g., his permanent 309 residence. 311 Visited emergency number: A visited emergency number is the emergency 312 number valid at the caller's current physical location. We 313 distinguish the visited emergency number if the caller is 314 traveling outside his home region. 316 Visited emergency dial string: A visited emergency dial string is the 317 dial string number valid at the caller's current physical 318 location. 320 3.7 Mapping 321 Mapping: Mapping is the process of resolving a location to one or 322 more PSAP URIs which directly identify a PSAP, or point to an 323 intermediary which knows about a PSAP and that is designated as 324 responsible for serving that location. 326 Mapping client: A mapping client interacts with the mapping server to 327 learn one or more PSAP URIs for a given location. 329 Mapping protocol: A protocol used to convey the mapping request and 330 response. 332 Mapping server: The mapping server holds information about the 333 location-to-PSAP URI mapping. 335 Mapping service: A network service which uses a distributed mapping 336 protocol to perform a mapping between a location and a PSAP, or 337 intermediary which knows about the PSAP, and is used to assist in 338 routing an emergency call. 340 4. Basic Actors 342 In order to support emergency services covering a large physical 343 area, various infrastructure elements are necessary, including 344 Internet Attachment Providers (IAPs), Application/Voice Service 345 Providers (ASP/VSPs), Emergency Service Routing Proxy (ESRP) 346 providers, mapping service providers, and PSAPs. 348 This section outlines which entities will be considered in the 349 routing scenarios discussed. 351 Location 352 Information +-----------------+ 353 |(1) |Internet | +-----------+ 354 v |Attachment | | | 355 +-----------+ |Provider | | Mapping | 356 | | | (3) | | Service | 357 | Emergency |<---+-----------------+-->| | 358 | Caller | | (2) | +-----------+ 359 | |<---+-------+ | ^ 360 +-----------+ | +----|---------+------+ | 361 ^ | | Location | | | 362 | | | Information<-+ | | 363 | +--+--------------+ |(5) | | (6) 364 | | | | | 365 | | +-----------v+ | | 366 | (4) | | | | | 367 +--------------+--->| ESRP |<--+---+ 368 | | | | | 369 | | +------------+ | 370 | | ^ | 371 | | (7) | | +----+--+ 372 | (8) | +------------>| | 373 +--------------+----------------------->| PSAP | 374 | | | | 375 |Application/ | +----+--+ 376 |Voice | 377 |Service | 378 |Provider | 379 +---------------------+ 381 Figure 1: Framework for emergency call routing 383 Figure 1 shows the interaction between the entities involved in the 384 call. There are a number of different deployment choices, as can be 385 easily seen from the figure. 387 Is the Internet Attachment Provider also the Application/Voice 388 Service Provider? In the Internet today these roles are typically 389 provided by different entities. As a consequence, the Application/ 390 Voice Service Provider is typically not able to directly determine 391 the physical location of the emergency caller. 393 The overlapping squares in the figure indicate that some functions 394 can be collapsed into a single entity. As an example, the 395 Application/Voice Service Provider might be the same entity as the 396 Internet Attachment Provider. There is, however, no requirement that 397 this must be the case. Additionally, we consider that end systems 398 might act as their own ASP/VSP, e.g., either for enterprises or for 399 residential users. 401 Various potential interactions between the entities depicted in 402 Figure 1 are described below: 404 1. Location information might be available to the end host itself. 406 2. Location information might, however, also be obtained from the 407 Internet Attachment Provider. 409 3. The emergency caller might need to consult a mapping service to 410 determine the PSAP (or other relevant information) that is 411 appropriate for the physical location of the emergency caller, 412 possibly considering other attributes such as appropriate 413 language support by the emergency call taker. 415 4. The emergency caller might get assistance for emergency call 416 routing by infrastructure elements that are emergency call 417 routing support entities, such as an Emergency Service Routing 418 Proxy (ESRP) in SIP. 420 5. Location information is used by emergency call routing support 421 entities for subsequent mapping requests. 423 6. Emergency call routing support entities might need to consult a 424 mapping service to determine where to route the emergency call. 426 7. For infrastructure-based emergency call routing (in contrast to 427 UE-based emergency call routing), the emergency call routing 428 support entity needs to forward the call to the PSAP. 430 8. The emergency caller may interact directly with the PSAP, where 431 the UE invokes mapping, and initiates a connection, without 432 relying on any intermediary emergency call routing support 433 entities. 435 5. High-Level Requirements 437 Below, we summarize high-level architectural requirements that guide 438 some of the component requirements detailed later in the document. 440 Re1. Application/Voice service provider existence: The initiation of 441 an IP-based emergency call SHOULD NOT assume the existence of an 442 Application/Voice Service Provider (ASP/VSP). 444 Motivation: The caller may not have an application/voice service 445 provider. For example, a residence may have its own DNS domain 446 and run its own SIP proxy server for that domain. On a larger 447 scale, a university might provide voice services to its students 448 and staff, but might not be a telecommunication provider. 450 Re2. International applicability: Regional, political and 451 organizational aspects MUST be considered during the design of 452 protocols and protocol extensions which support IP-based emergency 453 calls. 455 Motivation: It must be possible for a device or software developed 456 or purchased in one country to place emergency calls in another 457 country. System components should not be biased towards a 458 particular set of emergency numbers or languages. Also, different 459 countries have evolved different ways of organizing emergency 460 services, e.g., either centralizing them or having smaller 461 regional subdivisions such as United States counties or 462 municipalities handle emergency calls within their jurisdiction. 464 Re3. Distributed administration: Deployment of IP-based emergency 465 services MUST NOT depend on a single central administrative 466 authority. 468 Motivation: The design of the mapping protocol must make it 469 possible to deploy and administer emergency calling features on a 470 regional or national basis without requiring coordination with 471 other regions or nations. The system cannot assume, for example, 472 that there is a single global entity issuing certificates for 473 PSAPs, ASP/VSPs, IAPs or other participants. 475 Re4. Multi-mode communication: IP-based emergency calls MUST support 476 multiple communication modes, including, for example, audio, video 477 and text. 479 Motivation: Within the PSTN, voice and text telephony (often 480 called TTY or text-phone in North America) are the only commonly 481 supported media. Emergency calling must support a variety of 482 media. Such media should include voice, conversational text (RFC 483 4103 [7]), instant messaging and video. 485 Re5. Mapping result usability: The mapping protocol MUST return one 486 or more URIs that are usable within a standard signaling protocol 487 (i.e., without special emergency extensions). 489 Motivation: For example, a SIP URI which is returned by the 490 mapping protocol needs to be usable by any SIP capable phone 491 within a SIP initiated emergency call. This is in contrast to a 492 "special purpose" URI, which may not be recognizable by a legacy 493 SIP device. 495 Re6. PSAP URI accessibility: The mapping protocol MUST support 496 interaction between the client and server where no enrollment to a 497 mapping service exists or is required. 499 Motivation: The mapping server may well be operated by a service 500 provider, but access to the server offering the mapping must not 501 require use of a specific ISP or ASP/VSP. 503 Re7. Common data structures and formats: The mapping protocol SHOULD 504 support common formats for location data. 506 Motivation: Location databases should not need to be transformed 507 or modified in any unusual or unreasonable way in order for the 508 mapping protocol to use the data. For example, a database which 509 contains civic addresses used by location servers may be used for 510 multiple purposes and applications beyond emergency service 511 location-to-PSAP URI mapping. 513 Re8. Anonymous mapping: The mapping protocol MUST NOT require the 514 true identity of the target for which the location information is 515 attributed. 517 Motivation: Ideally, no identity information is provided via the 518 mapping protocol. Where identity information is provided, it may 519 be in the form of an unlinked pseudonym (RFC 3693 [4]). 521 6. Identifying the Caller's Location 523 Location can either be provided directly (by value), or via a pointer 524 (by reference), and represents either a civic location, or a 525 geographic location. An important question is how and when to attach 526 location information to the VoIP emergency signaling messages. In 527 general, we can distinguish three modes of operation of how a 528 location is associated with an emergency call: 530 UA-inserted: The caller's user agent inserts the location information 531 into the call signaling message. 533 UA-referenced: The caller's user agent provides a pointer (i.e., a 534 location reference), via a permanent or temporary identifier, to 535 the location information, which is stored by a location server 536 somewhere else and then retrieved by the PSAP, ESRP, or other 537 authorized entity. 539 Proxy-inserted: A proxy along the call path inserts the location or 540 location reference. 542 The following requirements apply: 544 Lo1. Reference datum: The mapping protocol MUST support the WGS-84 545 coordinate reference system and MAY support other coordinate 546 reference systems. 548 Motivation: Though many different datums exist around the world, 549 this document recommends the WGS-84 datum since it is designed to 550 describe the whole earth, rather than a single continent or other 551 region, and is commonly used to represent Global Positioning 552 System coordinates. 554 Lo2. Location delivery by-value: The mapping protocol MUST support 555 the delivery of location information using a by-value method, 556 though it MAY also support de-referencing a URL that references a 557 location object. 559 Motivation: The mapping protocol is not required to support the 560 ability to de-reference specific location references. 562 Lo3. Alternate community names: The mapping protocol MUST support 563 both the jurisdictional community name and the postal community 564 name fields within the PIDF-LO [8] data. 566 Motivation: The mapping protocol must accept queries with either 567 a postal or jurisdictional community name field, or both, and 568 provide appropriate responses. If a mapping query contains only 569 one community name and the database contains both jurisdictional 570 and postal community names, the mapping protocol response SHOULD 571 return both community names. 573 Lo4. Validation of civic location: The mapping protocol MUST support 574 location validation for civic locations (street addresses). 576 Motivation: Location validation provides an opportunity to help 577 ascertain ahead of time whether or not a successful mapping to the 578 appropriate PSAP will likely occur when it is required. 579 Validation may also help to avoid delays during emergency call 580 setup due to invalid location data. 582 Lo5. Validation resolution: The mapping protocol MUST support the 583 ability to provide ancillary information about the resolution of 584 location data used to retrieve a PSAP URI. 586 Motivation: The mapping server may not use all the data elements 587 in the provided location information to determine a match, or may 588 be able to find a match based on all of the information except for 589 some specific data elements. The uniqueness of this information 590 set may be used to differentiate among emergency jurisdictions. 591 Precision or resolution in the context of this requirement might 592 mean, for example, explicit identification of the data elements 593 that were used successfully in the mapping. 595 Lo6. Contact for location problems: The mapping protocol MUST 596 support a mechanism to contact an appropriate authority to resolve 597 mapping-related issues for the queried location. For example, the 598 querier may want to report problems with the response values or 599 indicate that the mapping database is mistaken on declaring a 600 civic location as non-existent. 602 Motivation: Initially, authorities may provide URLs where a human 603 user can report problems with an address or location. In 604 addition, web services may be defined to automate such reporting. 605 For example, the querier may wish to report that the mapping 606 database may be missing a newly-built or renamed street or house 607 number. 609 Lo7. Limits to validation: Successful validation of a civic location 610 MUST NOT be required to place an emergency call. 612 Motivation: In some cases, a civic location may not be considered 613 valid. This fact should not result in the call being dropped or 614 rejected by any entity along the call setup signaling path to the 615 PSAP. 617 Lo8. 3D sensitive mapping: The mapping protocol MUST implement 618 support for both 2D and 3D location information, and may accept 619 either a 2D or 3D mapping request as input. 621 Motivation: It is expected that queriers may provide either 2D or 622 3D data. When a 3D request is presented within an area only 623 defined by 2D data within the mapping server, the mapping result 624 would be the same as if the height or altitude coordinate had been 625 omitted from the mapping request. 627 Lo9. Database type indicator: The mapping protocol MAY support a 628 mechanism which provides an indication describing a specific type 629 of location database used. 631 Motivation: It is useful to know the source of the data stored in 632 the database used for location validation, either for civic or 633 geographic location matching. In the United States, sources of 634 data could include the United States Postal Service, the Master 635 Street Address Guide (MSAG) or commercial map data providers. 637 7. Emergency Service Identifier 639 Emergency service identifiers are protocol constants that allow 640 protocol entities such as SIP proxy servers to distinguish emergency 641 calls from non-emergency calls and to identify the specific emergency 642 service desired. Emergency service identifiers are a subclass of 643 service identifiers that more generally identify services reachable 644 by callers. An example of a service identifier is the service URN 645 [11], but other identifiers, such as tel URIs [6], may also serve 646 this role during a transition period. 648 Since this document only addresses emergency services, we use the 649 terms "emergency service identifier" and "service identifier" 650 interchangeably. Requirements for these identifiers include: 652 Id1. Multiple emergency services: The mapping protocol MUST be able 653 to distinguish between different emergency services, 654 differentiated by different service identifiers. 656 Motivation: Some jurisdictions may offer multiple types of 657 emergency services that operate independently and can be contacted 658 directly, for example, fire, police and ambulance services. 660 Id2. Extensible emergency service identifiers: The mapping protocol 661 MUST support an extensible list of emergency identifiers, though 662 it is not required to provide mappings for every possible service. 664 Motivation: Extensibility is required since new emergency 665 services may be introduced over time, either globally or in some 666 jurisdictions. The availability of emergency services depends on 667 the locations. For example, the Netherlands are unlikely to offer 668 a mountain rescue service. 670 Id3. Discovery of emergency number: The mapping protocol MUST be 671 able to return the location-dependent emergency number for the 672 location indicated in the query. 674 Motivation: Users are trained to dial the appropriate emergency 675 number to reach emergency services. There needs to be a way to 676 figure out the emergency number at the current location of the 677 caller. 679 Id4. Home emergency number recognition: User equipment MUST be able 680 to translate a home emergency number into an emergency service 681 identifier. 683 Motivation: The UE could be pre-provisioned with the appropriate 684 information in order to perform such a translation or could 685 discover the emergency number by querying the mapping protocol 686 with its home location. 688 Id5. Emergency number replacement: There SHOULD be support for 689 replacement of the emergency number with the appropriate emergency 690 service identifier for each signaling protocol used for an 691 emergency call, based on local conventions, regulations, or 692 preference (e.g., as in the case of an enterprise). 694 Motivation: Any signaling protocol requires the use of some 695 identifier to indicate the called party, and the user equipment 696 may lack the capability to determine the actual service URL (PSAP 697 URI). The use of local conventions may be required as a 698 transition mechanism. Since relying on recognizing local 699 numbering conventions makes it difficult for devices to be used 700 outside their home context and for external devices to be 701 introduced into a network, protocols should use standardized 702 emergency service identifiers. 704 Id6. Emergency service identifier marking: Signaling protocols MUST 705 support emergency service identifiers to mark a call as an 706 emergency call. 708 Motivation: Marking ensures proper handling as an emergency call 709 by downstream elements that may not recognize, for example, a 710 local variant of a logical emergency address. This marking 711 mechanism is related to, but independent of, marking calls for 712 prioritized call handling [9]. 714 Id7. Handling unrecognized emergency service identifiers: There MUST 715 be support for calls which are initiated as emergency calls even 716 if the specific emergency service requested is not recognized by 717 the ESRP. Such calls will then be routed to a generic emergency 718 service. 720 Motivation: Fallback routing allows new emergency services to be 721 introduced incrementally, while avoiding non-routable emergency 722 calls. For example, a call for marine rescue services would be 723 routed to a general PSAP if the caller's location does not offer 724 marine rescue services yet. 726 Id8. Return fallback service identifier: The mapping protocol must 727 be able to report back the actual service mapped if the mapping 728 protocol substitutes another service for the one requested. 730 Motivation: A mapping server may be configured to automatically 731 look up the PSAP for another service if the user-requested service 732 is not available for that location. For example, if there is no 733 marine rescue service, the mapping protocol might return the PSAP 734 URL for general emergencies and include the "urn:service.sos" 735 identifier in the response to alert the querier to that fact. 737 Id9. Discovery of visited emergency numbers: There MUST be a 738 mechanism to allow the end device to learn visited emergency 739 numbers. 741 Motivation: Travelers visiting a foreign country may observe the 742 local emergency number, e.g., seeing it painted on the side of a 743 fire truck, and then rightfully expect to be able to dial that 744 emergency number. Similarly, a local "good Samaritan" may use a 745 tourist's cell phone to summon help. 747 8. Mapping Protocol 749 There are two basic approaches to invoke the mapping protocol. We 750 refer to these as caller-based and mediated. In each case, the 751 mapping client initiates a request to a mapping server via a mapping 752 protocol. A proposed mapping protocol, LoST, is outlined in [12]. 754 For caller-based resolution, the caller's user agent invokes the 755 mapping protocol to determine the appropriate PSAP based on the 756 location provided. The resolution may take place well before the 757 actual emergency call is placed, or at the time of the call. 759 For mediated resolution, an emergency call routing support entity, 760 such as a SIP (outbound) proxy or redirect server invokes the mapping 761 service. 763 Since servers may be used as outbound proxy servers by clients that 764 are not in the same geographic area as the proxy server, any proxy 765 server has to be able to translate any caller location to the 766 appropriate PSAP. (A traveler may, for example, accidentally or 767 intentionally configure its home proxy server as its outbound proxy 768 server, even while far away from home.) 770 Ma1. Baseline query protocol: A mandatory-to-implement protocol MUST 771 be specified. 773 Motivation: An over-abundance of similarly-capable choices appears 774 undesirable for interoperability. 776 Ma2. Extensible protocol: The mapping protocol MUST be designed to 777 support the extensibility of location data elements, both for new 778 and existing fields. 780 Motivation: This is needed, for example, to accommodate future 781 extensions to location information that might be included in the 782 PIDF-LO ([8]). 784 Ma3. Incrementally deployable: The mapping protocol MUST be designed 785 to support its incremental deployment. 787 Motivation: It must not be necessary, for example, to have a 788 global street level database before deploying the system. It is 789 acceptable to have some misrouting of calls when the database does 790 not (yet) contain accurate PSAP service area information. 792 Ma4. Any time mapping: The mapping protocol MUST support the ability 793 of the mapping function to be invoked at any time, including while 794 an emergency call is in process and before an emergency call is 795 initiated. 797 Motivation: Used as a fallback mechanism only, if a mapping query 798 fails at emergency call time, it may be advantageous to have prior 799 knowledge of the PSAP URI. This prior knowledge would be obtained 800 by performing a mapping query at any time prior to an emergency 801 call. 803 Ma5. Anywhere mapping: The mapping protocol MUST support the ability 804 to provide mapping information in response to an individual query 805 from any (earthly) location, regardless of where the mapping 806 client is located, either geographically or by network location. 808 Motivation: The mapping client, such as an ESRP, may not 809 necessarily be anywhere close to the caller or the appropriate 810 PSAP, but must still be able to obtain mapping information. 812 Ma6. Appropriate PSAP: The mapping protocol MUST support the routing 813 of an emergency call to the PSAP responsible for a particular 814 geographic area. 816 Motivation: Routing to the wrong PSAP will result in delays in 817 handling emergencies as calls are redirected, and therefore will 818 also result in inefficient use of PSAP resources at the initial 819 point of contact. It is important that the location determination 820 mechanism not be fooled by the location of IP telephony gateways 821 or dial-in lines into a corporate LAN (and dispatch emergency help 822 to the gateway or campus, rather than the caller), multi-site LANs 823 and similar arrangements. 825 Ma7. Multiple PSAP URIs: The mapping protocol MUST support a method 826 to return multiple PSAP URIs which cover the same geographic area. 828 Motivation: Different contact protocols (e.g., PSTN via tel URIs 829 and IP via SIP URIs) may be routed to different PSAPs. Less 830 likely, two PSAPs may overlap in their coverage region. 832 Ma8. Single primary URI per contact protocol: Though the mapping 833 protocol may be able to include multiple URIs in the response, it 834 SHOULD return only one primary URI per contact protocol used, so 835 that clients are not required to select among different targets 836 for the same contact protocol. 838 Motivation: There may be two or more URIs returned when multiple 839 contact protocols are available (e.g., SIP and SMS). The client 840 may select among multiple contact protocols based on its 841 capabilities, preference settings, or availability. 843 Ma9. URI alternate contact: In addition to returning a primary 844 contact, the mapping protocol MUST support the return of a PSAP 845 URI or contact method explicitly marked as an alternate contact 846 for use when a fallback contact is needed. 848 Motivation: There may be multiple ways to provide addresses of 849 backup PSAPs, including the mapping protocol, DNS lookup via NAPTR 850 and SRV, or call routing by SIP proxies. 852 Ma10. Non-preferred URI schemes: The mapping protocol MAY support 853 the return of a less preferred URI scheme, such as a tel URI. 855 Motivation: In order to provide incremental support to non-IP 856 PSAPs it may be necessary to be able to complete an emergency call 857 via the PSTN. 859 Ma11. URI properties: The mapping protocol MUST support the ability 860 to provide ancillary information about a contact that allows the 861 mapping client to determine relevant properties of the PSAP URI. 863 Motivation: In some cases, the same geographic area is served by 864 several PSAPs, for example, a corporate campus might be served by 865 both a corporate security department and the municipal PSAP. The 866 mapping protocol should then return URIs for both, with 867 information allowing the querying entity to choose one or the 868 other. This determination could be made by either an ESRP, based 869 on local policy, or by direct user choice, in the case of caller- 870 based methods. 872 Ma12. Mapping referral: The mapping protocol MUST support a 873 mechanism for the mapping client to contact any mapping server and 874 be referred to another mapping server that is more qualified to 875 answer the query. 877 Motivation: Referrals help mitigate the impact of incorrect 878 configuration that directs a client to the wrong initial mapping 879 server. 881 Ma13. Split responsibility: The mapping protocol MUST support the 882 division of data subset handling between multiple mapping servers 883 within a single level of a civic location hierarchy. 885 Motivation: For example, two mapping servers for the same city or 886 county may handle different streets within that city or county. 888 Ma14. URL for error reporting: The mapping protocol MUST support the 889 ability to return a URL that can be used to report a suspected or 890 known error within the mapping database. 892 Motivation: If an error is returned, for example, there needs to 893 be a URL which points to a resource which can explain or 894 potentially help resolve the error. 896 Ma15. Resilience to failure: The mapping protocol MUST support a 897 mechanism which enables the client to fail over to different 898 (replica) mapping server. 900 Motivation: The failure of a mapping server should not preclude 901 the mapping client from receiving an answer to its query. 903 Ma16. Traceable resolution: The mapping protocol SHOULD support the 904 ability of the mapping client to be able to determine the entity 905 or entities that provided the emergency address resolution 906 information. 908 Motivation: To improve reliability and performance, it is 909 important to be able to trace which servers contributed to the 910 resolution of a query. 912 Ma17. Minimal additional delay: Mapping protocol execution SHOULD 913 minimize the amount of delay within the overall call-setup time. 915 Motivation: Since outbound proxies will likely be asked to 916 resolve the same geographic coordinates repeatedly, a suitable 917 time-limited caching mechanism should be supported. 919 Ma18. Alternate mapping sources: The mapping protocol MUST implement 920 a mechanism that allows for the retrieval of mapping information 921 from different sources. 923 Motivation: This provides the possibility of having available 924 alternative sources of mapping information when the normal source 925 is unavailable or unreachable. 927 Ma19. Freshness indication: The mapping protocol SHOULD support an 928 indicator describing how current the information provided by the 929 mapping source is. 931 Motivation: This is especially useful when an alternate mapping is 932 requested, and alternative sources of mapping data may not have 933 been created or updated with the same set of information or within 934 the same timeframe. Differences in currency between mapping data 935 contained within mapping sources should be minimized. 937 9. Security Considerations 939 Threats and security requirements are discussed in a separate 940 document [10]. 942 10. IANA Considerations 944 This document does not require actions by the IANA. 946 11. Contributors 948 The information in this document is partially derived from text 949 written by the following contributors: 951 Nadine Abbott nabbott@telcordia.com 953 Hideki Arai arai859@oki.com 955 Martin Dawson Martin.Dawson@andrew.com 957 Motoharu Kawanishi kawanishi381@oki.com 959 Brian Rosen br@brianrosen.net 961 Richard Stastny Richard.Stastny@oefeg.at 963 Martin Thomson Martin.Thomson@andrew.com 965 James Winterbottom James.Winterbottom@andrew.com 967 12. Acknowledgments 969 In addition to thanking those listed above, we would like to also 970 thank Guy Caron, Barry Dingle, Keith Drage, Tim Dunn, Patrik 971 Faltstrom, Clive D.W. Feather, Raymond Forbes, Randall Gellens, 972 Michael Haberler, Michael Hammer, Ted Hardie, Gunnar Hellstrom, 973 Cullen Jennings, Marc Linsner, Rohan Mahy, Patti McCalmont, Don 974 Mitchell, John Morris, Andrew Newton, Steve Norreys, Jon Peterson, 975 James Polk, Benny Rodrig, John Rosenberg, Jonathan Rosenberg, John 976 Schnizlein, Shida Schubert, James Seng, Byron Smith, Barbara Stark, 977 Richard Stastny, Tom Taylor, Hannes Tschofenig, and Nate Wilcox for 978 their helpful input. 980 13. References 982 13.1 Normative References 984 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 985 Levels", BCP 14, RFC 2119, March 1997. 987 13.2 Informative References 989 [2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., 990 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: 991 Session Initiation Protocol", RFC 3261, June 2002. 993 [3] Charlton, N., Gasson, M., Gybels, G., Spanner, M., and A. van 994 Wijk, "User Requirements for the Session Initiation Protocol 995 (SIP) in Support of Deaf, Hard of Hearing and Speech-impaired 996 Individuals", RFC 3351, August 2002. 998 [4] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J. 999 Polk, "Geopriv Requirements", RFC 3693, February 2004. 1001 [5] Peterson, J., "Common Profile for Instant Messaging (CPIM)", 1002 RFC 3860, August 2004. 1004 [6] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, 1005 December 2004. 1007 [7] Hellstrom, G. and P. Jones, "RTP Payload for Text 1008 Conversation", RFC 4103, June 2005. 1010 [8] Peterson, J., "A Presence-based GEOPRIV Location Object 1011 Format", RFC 4119, December 2005. 1013 [9] Schulzrinne, H. and J. Polk, "Communications Resource Priority 1014 for the Session Initiation Protocol (SIP)", RFC 4412, 1015 February 2006. 1017 [10] Taylor, T., "Security Threats and Requirements for Emergency 1018 Call Marking and Mapping", draft-ietf-ecrit-security-threats-03 1019 (work in progress), July 2006. 1021 [11] Schulzrinne, H., "A Uniform Resource Name (URN) for Services", 1022 draft-ietf-ecrit-service-urn-04 (work in progress), 1023 August 2006. 1025 [12] Hardie, T., "LoST: A Location-to-Service Translation Protocol", 1026 draft-hardie-ecrit-lost-00 (work in progress), March 2006. 1028 [13] Wijk, A. and G. Gybels, "Framework for real-time text over IP 1029 using the Session Initiation Protocol (SIP)", 1030 draft-ietf-sipping-toip-06 (work in progress), August 2006. 1032 Authors' Addresses 1034 Henning Schulzrinne 1035 Columbia University 1036 Department of Computer Science 1037 450 Computer Science Building 1038 New York, NY 10027 1039 US 1041 Phone: +1 212 939 7004 1042 Email: hgs+ecrit@cs.columbia.edu 1043 URI: http://www.cs.columbia.edu 1045 Roger Marshall (editor) 1046 TeleCommunication Systems 1047 2401 Elliott Avenue 1048 2nd Floor 1049 Seattle, WA 98121 1050 US 1052 Phone: +1 206 792 2424 1053 Email: rmarshall@telecomsys.com 1054 URI: http://www.telecomsys.com 1056 Intellectual Property Statement 1058 The IETF takes no position regarding the validity or scope of any 1059 Intellectual Property Rights or other rights that might be claimed to 1060 pertain to the implementation or use of the technology described in 1061 this document or the extent to which any license under such rights 1062 might or might not be available; nor does it represent that it has 1063 made any independent effort to identify any such rights. Information 1064 on the procedures with respect to rights in RFC documents can be 1065 found in BCP 78 and BCP 79. 1067 Copies of IPR disclosures made to the IETF Secretariat and any 1068 assurances of licenses to be made available, or the result of an 1069 attempt made to obtain a general license or permission for the use of 1070 such proprietary rights by implementers or users of this 1071 specification can be obtained from the IETF on-line IPR repository at 1072 http://www.ietf.org/ipr. 1074 The IETF invites any interested party to bring to its attention any 1075 copyrights, patents or patent applications, or other proprietary 1076 rights that may cover technology that may be required to implement 1077 this standard. Please address the information to the IETF at 1078 ietf-ipr@ietf.org. 1080 Disclaimer of Validity 1082 This document and the information contained herein are provided on an 1083 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1084 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 1085 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 1086 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 1087 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1088 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1090 Copyright Statement 1092 Copyright (C) The Internet Society (2006). This document is subject 1093 to the rights, licenses and restrictions contained in BCP 78, and 1094 except as set forth therein, the authors retain all their rights. 1096 Acknowledgment 1098 Funding for the RFC Editor function is currently provided by the 1099 Internet Society.