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'9' Summary: 2 errors (**), 0 flaws (~~), 7 warnings (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force James M. Polk 3 Internet Draft Cisco Systems 4 Expiration: April 27th, 2003 Brian Rosen 5 File: draft-polk-sipping-location-requirements-01.txt Marconi 7 Session Initiation Protocol Location Conveyance 9 October 27th, 2003 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance 14 with all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six 22 months and may be updated, replaced, or obsoleted by other 23 documents at any time. It is inappropriate to use Internet-Drafts 24 as reference material or to cite them other than as "work in 25 progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt 30 The list of Internet-Draft Shadow Directories can be accessed 31 at http://www.ietf.org/shadow.html. 33 Abstract 35 This document presents the framework and requirements for an 36 extension to the Session Initiation Protocol (SIP) [1] for 37 conveyance of user location information from a Session Initiation 38 Protocol (SIP) user agent to another SIP entity. We consider cases 39 where location information is conveyed from end to end, as well as 40 cases where message routing by intermediaries is influenced by the 41 location of the session initiator. 43 Table of Contents 45 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 46 1.1 Conventions . . . . . . . . . . . . . . . . . . . . . . . 3 47 1.2 Changes from -00 . . . . . . . . . . . . . . . . . . . . 3 48 2. In the Body or in a Header . . . . . . . . . . . . . . . . . 3 49 3. Scope of Location in a Message Body . . . . . . . . . . . . . 4 50 4. Requirements for UA-to-UA Location Conveyance . . . . . . . . 4 51 5. Requirements for UA-to-Proxy Server Location Conveyance . . . 5 52 6. Additional Requirements for Emergency Calls . . . . . . . . . 5 53 7. Current Known Open issues . . . . . . . . . . . . . . . . . . 6 54 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 55 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 7 56 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 57 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 58 12. Author Information . . . . . . . . . . . . . . . . . . . . . 8 60 1. Introduction 62 This document presents the framework and requirements for an 63 extension to the Session Initiation Protocol (SIP) [1] for 64 conveyance of user location information object described by [7] from 65 a SIP User Agent to another SIP entity. 67 There are several situations in which it is appropriate for SIP to 68 be used to convey Location Information (LI) from one SIP entity to 69 another. This document specifies requirements when a SIP UAC knows 70 its location by some means not specified herein, and needs to inform 71 another SIP entity. One example is to reach your nearest pizza 72 parlor. A chain of pizza parlors may have a single well known uri 73 (sip:pizzaparlor.com), that is forwarded to the closest franchise by 74 the pizzaparlor.com proxy server. The receiving franchise UAS uses 75 the location information of the UAC to schedule your delivery. 77 Another important example is emergency calling. A call to 78 sip:sos@example.com is an emergency call as in [3]. The example.com 79 proxy server must route the call to the correct emergency response 80 center (ERC) determined by the location of the caller. At the ERC, 81 the UAS must determine the correct police/fire/ambulance/... 82 service, which is also based on your location. In many 83 jurisdictions, accurate location information is a required component 84 of a call to an emergency center. 86 A third example is a direction service, which might give you verbal 87 directions to a venue from your present position. This is a case 88 where only the destination UAS needs to receive the location 89 information. 91 This document does not discuss how the UAC discovers or is 92 configured with its location (either coordinate based or civil 93 based). It also does not discuss the contents of the Location 94 Object (LO). It does specify the requirements for the "using 95 protocol" in [7]. 97 1.1 Conventions used in this document 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL 100 NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and 101 "OPTIONAL" in this document are to be interpreted as described 102 in [2]. 104 1.2 Changes from -00 Version 106 This is a list of the changes that have been made from the -00 107 version of this ID: 109 - Brian Rosen was brought on as a co-author 111 - Requirements that a location header were negatively received in 112 the previous version of this document. AD and chair advice was to 113 move all location information into a message body (and stay away 114 from headers) 116 - Added a section of "emergency call" specific requirements 118 - Added an Open Issues section to mention what hasn't been resolved 119 yet in this effort 121 2. In the Body or in a Header 123 When one user agent wants to inform another user agent where they 124 are, it seems reasonable to have this accomplished by placing the 125 location information (coordinate or civil) in an S/Mime registered 126 and encoded message body, and sending it as part of a SIP request or 127 response. No routing of the request based on the location 128 information is required in this case; therefore no SIP Proxies 129 between these two UAs need to view the location information 130 contained in the SIP messages. 132 Although SIP [1} does not permit a proxy server to modify or delete 133 a body, there is no restriction on viewing bodies. However, S/MIME 134 protection implemented on bodies is only specified between UAS and 135 UAC and if engaged, would render the location object opaque to a 136 proxy server. This problem is similar to that raised in Session 137 Policy [8], where an intermediary may need information in a body, 138 such as IP address of media streams or codec choices to route a call 139 properly. Requirements in [8] are applicable to routing based on 140 location, and are incorporated in these requirements by reference. 142 It is conceivable to create a new header for location information. 143 However, [7] prefers S/MIME for security of Location Information, 144 and indeed S/MIME is preferable in SIP for protecting one part of a 145 message. Accordingly, these requirements specify location be 146 carried in a body. 148 It is the use of S/MIME however, that limits routing based on 149 location. Therefore, it seems appropriate to require that, where 150 routing is dependent on location, protection of the location 151 information object be accomplished by other mechanisms, probably TLS 152 ("sips:" from [1]). It is envisioned that S/MIME SHOULD be used 153 when location information is not required by proxy servers, and TLS 154 SHOULD be used when it is. 156 This document does not address the behavior or configuration of SIP 157 Proxy Servers in these cases in order to accomplish location- 158 sensitive routing. That is out of scope, and left for further 159 (complementary) efforts. 161 3. Scope of Location in a Message Body 163 If the location information is to be contained within a message 164 body, and either another body (SDP for example) is also to be sent 165 in the message, or the LO is to be protected with S/MIME, the rules 166 stated in section 7 of [1] regarding multipart MIME bodies MUST be 167 followed. The format and privacy/security rules of the location 168 information SHOULD be defined within the Geopriv WG. 170 4. Requirements for UA-to-UA Location Conveyance 172 The following are the requirements for UA-to-UA Location Conveyance 173 situations: 175 U-U1 - MUST work with dialog-initiating SIP Requests and responses, 176 as well as the SIP MESSAGE method[4], and SHOULD work with 177 most SIP messages. 179 U-U2 - UAC Location information SHOULD remain confidential in route 180 to the destination UA 182 U-U3 - The privacy and security rules established within the 183 Geopriv Working Group that would categorize SIP as a 'using 184 protocol' MUST be met [7] 186 5. Requirements for UA-to-Proxy Server Location Conveyance 188 The following are the requirements for UA-to-Proxy Server Location 189 Conveyance situations: 191 U-PS1 - MUST work with dialog-initiating SIP Requests and 192 responses, as well as the SIP MESSAGE method[4], and SHOULD 193 work with most SIP messages. 195 U-PS2 - UAC location information SHOULD remain confidential in 196 route to the destination, but MUST be useable by 197 intermediary proxy servers. 199 U-PS3 - The privacy and security rules established within the 200 Geopriv Working Group which would categorize SIP as a 201 'using protocol' MUST be met [7] 203 U-PS4 - Modification or removal of the LO by proxy servers MUST NOT 204 be required 206 U-PS5 - any mechanism used to prevent unwanted observation of this 207 Location Header(s) CANNOT fail the SIP Request if not 208 understood by intermediary SIP entities or the destination 209 UAS 211 U-PS6 � It MUST be possible for a proxy server to assert the 212 validity of the location information provided by the UA. 213 Alternatively, it is acceptable for there to be a mechanism 214 for a proxy server to assert a location object itself. 216 6. Additional Requirements for Emergency Calls 218 Emergency calls have requirements that are not generally important 219 to other uses for location in SIP: 221 Emergency calls presently have between 2 and 8-second call setup 222 times. There is ample evidence that the longer call setup end of 223 the range causes an unacceptable number of callers to abandon the 224 call before it is completed. Two-second call completion time is a 225 goal of many existing emergency call centers. Allocating 25% of the 226 call set up for processing privacy concerns seems reasonable; 1 227 second would be 50% of the goal, which seems unacceptable; less than 228 0.5 second seems unachievable, therefore: 230 E-1 - Privacy mechanisms MUST add no more than 0.5 second of call 231 setup time when implemented in present technology UAs and 232 Proxy Servers. 234 It may be acceptable for full privacy mechanisms related to the 235 location of the UAC (and it's user) to be tried on an initial 236 attempt to place a call, as long as the call attempt may be retried 237 without the mechanism if the first attempt fails. Abandoning 238 privacy in cases of failure of the privacy mechanism might be 239 subject to user preference, although such a feature would be within 240 the domain of a UA implementation and thus not subject to 241 standardization. It should be noted that some jurisdictions have 242 laws that explicitly deny any expectation of location privacy when 243 making an emergency call. 245 E-2 � Privacy mechanisms MUST NOT be mandatory for successful 246 conveyance of location during an (sos-type) emergency call. 248 E-3 � The retention and retransmission policy of the ERC must be 249 able to be made available to the user, and override the 250 user's normal policy when local regulation governs such 251 retention and retransmission. As in E-2 above, requiring the 252 use of the ERC's retention and/or retransmission policy may 253 be subject to user preference although in most jurisdictions, 254 local laws specify such policies and may not be overridden by 255 user preference. 257 7. Current Known Open issues 259 This is a list of open issues that have not yet been addressed to 260 conclusion: 262 - Whether self signed S/MIME bodies can work in both directions in 263 the emergency call scenario (to and from an ERC) as in [9]. It 264 appears that document covers self-signed certs from the UA to ERC 265 direction, but it is not clear it solves communications in the 266 reverse direction. 268 - If S/MIME is chosen as a SHOULD (in general, vs. TLS), this doc 269 might consider stipulating a special purpose Proxy (an "emergency 270 services" proxy) that can process location information (a Geopriv 271 LO) and route the message directly to the appropriate ERC. 273 At Issue: plain "vanilla" proxies probably won't have the 274 capabilities to route based on location information in the 275 near future, but should that timing be considered here? 277 8. Security Considerations 279 Conveyance of geo-location of a UAC is problematic for many reasons. 280 This document calls for that conveyance to normally be accomplished 281 through secure message body means (like S/MIME or TLS). In cases 282 where a session set-up is routed based on the location of the UAC 283 initiating the session or SIP MESSAGE, securing the location with an 284 end-to-end mechanism such as S/MIME is problematic. 286 9. IANA Considerations 288 There are no IANA considerations within this document at this time. 290 10. Acknowledgements 292 To Dave Oran for helping to shape this idea. To Jon Peterson and 293 Dean Willis on guidance of the effort. 295 11. References - Normative 297 [1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. 298 Peterson, R. Sparks, M. Handley, E. Schooler, "SIP: Session 299 Initiation Protocol ", RFC 3261, June 2002 301 [2] S. Bradner, "Key words for use in RFCs to indicate requirement 302 levels," RFC 2119, Mar. 1997. 304 [3] H. Schulzrinne, "draft-schulzrinne-sipping-sos-04.txt", Internet 305 Draft, Jan 03, Work in progress 307 [4] B. Campbell, Ed., J. Rosenberg, H. Schulzrinne, C. Huitema, D. 308 Gurle, "Session Initiation Protocol (SIP) Extension for Instant 309 Messaging" , RFC 3428, December 2002 311 [5] J. Polk, J. Schnizlein, M. Linsner, " draft-ietf-geopriv-dhcp-lci- 312 option-02.txt", Internet Draft, Aug 2003, Work in progress 314 [6] H. Schulzrinne, "draft-schulzrinne-geopriv-dhcp-civil-01.txt", 315 Internet Draft, Feb 03, Work in progress 317 [7] J. Cuellar, J. Morris, D. Mulligan, J. Peterson. J. Polk, "draft- 318 ietf-geopriv-reqs-03.txt", Internet Draft, Mar 03, Work in 319 progress 321 [8] J. Rosenberg, "Requirements for Session Policy for the Session 322 Initiation Protocol�, draft-ietf-sipping-session-policy-req-00", 324 [9] C. Jennings, "draft-jennings-sipping-certs-01.txt", Internet 325 Draft, "work in progress", July 2003 327 12. Author Information 329 James M. Polk 330 Cisco Systems 331 2200 East President George Bush Turnpike 332 Richardson, Texas 75082 USA 333 jmpolk@cisco.com 335 Brian Rosen 336 Marconi Communications, Inc. 337 2000 Marconi Drive 338 Warrendale, PA 15086 339 Brian.rosen@marconi.com 341 "Copyright (C) The Internet Society (February 23rd, 2001). 342 All Rights Reserved. 344 This document and translations of it may be copied and furnished to 345 others, and derivative works that comment on or otherwise explain it 346 or assist in its implementation may be prepared, copied, published 347 and distributed, in whole or in part, without restriction of any 348 kind, provided that the above copyright notice and this paragraph 349 are included on all such copies and derivative works. However, this 350 document itself may not be modified in any way, such as by removing 351 the copyright notice or references to the Internet Society or other 352 Internet organizations, except as needed for the purpose of 353 developing Internet standards in which case the procedures for 354 copyrights defined in the Internet Standards process must be 355 followed, or as required to translate it into languages other than 356 English. 358 The limited permissions granted above are perpetual and will not be 359 revoked by the Internet Society or its successors or assigns. 361 This document and the information contained herein is provided on an 362 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 363 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 364 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 365 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 366 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." 368 The Expiration date for this Internet Draft is: 370 April 27th, 2004