idnits 2.17.1 draft-ietf-geopriv-dhcp-lci-option-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by 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 == It seems as if not all pages are separated by form feeds - found 0 form feeds but 14 pages Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- -- 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.) -- Couldn't find a document date in the document -- date freshness check skipped. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: 'RFC 2434' on line 379 -- Possible downref: Non-RFC (?) normative reference: ref. '5' -- Possible downref: Non-RFC (?) normative reference: ref. '6' Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 5 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Engineering Task Force J. Polk 2 Internet Draft J. Schnizlein 3 Expiration: June 8th, 2004 M. Linsner 4 File: draft-ietf-geopriv-dhcp-lci-option-03.txt Cisco Systems 6 Dynamic Host Configuration Protocol Option for 7 Coordinate-based Location Configuration Information 9 December 8th, 2003 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 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 documents 23 at any time. It is inappropriate to use Internet-Drafts as 24 reference material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt 29 The list of Internet-Draft Shadow Directories can be accessed 30 at http://www.ietf.org/shadow.html. 32 Abstract 34 This document specifies a Dynamic Host Configuration Protocol Option 35 for the coordinate-based geographic location of the client. The 36 Location Configuration Information (LCI) includes latitude, 37 longitude, and altitude, with resolution indicators for each. The 38 reference datum for these values is also included. 40 Table of Contents 42 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 43 1.1 Conventions . . . . . . . . . . . . . . . . . . . . . . 3 44 1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . 3 45 1.3 Rationale . . . . . . . . . . . . . . . . . . . . . . . 4 46 2. Location Configuration Information (LCI) Elements . . . . . . 4 47 2.1 Elements of the Location Configuration Information . . . 5 48 3. Security Considerations . . . . . . . . . . . . . . . . . . 8 49 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 50 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 51 Appendix Calculations of Imprecision possible with the DHC LCI . 9 52 A.1 LCI of "White House" (Example 1) . . . . . . . . . . . . 9 53 A.2 LCI of "Sears Tower" (Example 2) . . . . . . . . . . . . 12 54 6. Normative References . . . . . . . . . . . . . . . . . . . . 12 55 7. Informational References . . . . . . . . . . . . . . . . . . 13 56 8. Author Information . . . . . . . . . . . . . . . . . . . . . 13 58 1. Introduction 60 This document specifies a Dynamic Host Configuration Protocol [1] 61 Option for coordinate-based geographic location of the client, to be 62 provided by the server. 64 The DHCP server is assumed to have determined the location from the 65 Circuit-ID Relay Agent Information Option (RAIO) defined (as SubOpt 66 1) in [2]. In order to translate the circuit (switch port 67 identifier) into a location, the DHCP server is assumed to have 68 access to a service that maps from circuit-ID to the location at 69 which the circuit connected to that port terminates in the building; 70 for example, the location of the wall jack. 72 An important feature of this specification is that after the 73 relevant DHC exchanges have taken place, the location information 74 is stored on the end device rather than somewhere else, where 75 retrieving it might be difficult in practice. 77 Another important feature of this LCI is its inclusion of a 78 resolution parameter for each of the dimensions of location. 79 Because this resolution parameter need not apply to all dimensions 80 equally, a resolution value is included for each of the 3 location 81 elements. 83 This resolution method provides a natural ability for the device to 84 hide from the center point of the bounding area as this resolution 85 method is determined via the inherent effects of binary 86 representation; or, this resolution mechanism could be used to 87 define a geographic area. This would be useful when a group of 88 clients would want to be known as the same geo-location, possibly 89 all users in a room of a building would use the same LCI value. 91 Then the using application could use that value as a key for lookup 92 in another data source. This is similar to one of the mechanisms 93 utilized in the North American E911 systems today. 95 Resolution does not define how Geographic Privacy policy should 96 relate to precision. 98 The resulting location information using this resolution method is a 99 small fixed length Configuration Information that can be easily 100 carried in protocols, such as DHCP, which have limited packet size 101 because this LCI is only 18 bytes long. 103 Finally, the appendix this document provides some arithmetic 104 examples of the implication of different resolution values on the 105 La/Lo/Alt. 107 1.1 Conventions used in this document 109 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 110 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 111 document are to be interpreted as described in [3]. 113 1.2 Motivation 115 As applications such as IP Telephony are replacing conventional 116 telephony, users are expecting the same (or greater) level of 117 services with the new technology. One service offered by 118 conventional telephony that is missing, in any standardized fashion, 119 within IP Telephony is for a user to be automatically located by 120 emergency responders, in a timely fashion, when the user summons 121 help (by dialing 911 in North America, for example). Unless strict 122 administrative rules are followed, the mobility of a wired Ethernet 123 device within a campus negates any opportunity for an emergency 124 responder to locate the device with any degree of expediency. Users 125 do not want to give up the mobility IP Telephony offers. Informing 126 the host device of its geo-location at host configuration time will 127 allow the device to utilize this geo-location information to inform 128 others of it's current geo-location, if the user and/or application 129 so desires. 131 The goal of this option is to enable a wired Ethernet host to 132 obtain its location, which it could provide to an emergency 133 responder, as one example. 135 Wireless hosts can utilize this option to gain knowledge of the 136 location of the radio access point used during host configuration, 137 but would need some more exotic mechanisms, maybe GPS, or maybe a 138 future DHCP option, which includes a list of geo-locations like that 139 defined here, containing the locations of the radio access points 140 that are close to the client. 142 1.3 Rationale 144 Within the LCI described here, Latitude and Longitude are 145 represented in fixed-point 2s-complement binary degrees, for the 146 economy of a smaller option size compared to a string encoding of 147 digits in [7]. The integer parts of these fields are 9 bits long to 148 accommodate +/- 180 degrees. The fractional part is 25 bits long, 149 better than the precision of 7 decimal digits. Each parameter is 40 150 bits total, in length. 152 Altitude is determined by the Altitude Type (AT) indicated by the 153 AT field, which is 4 bits long. Two Altitude Types are defined 154 here, meters (code=1) and floors (code=2), both of which are 2s- 155 complement fixed-point with 8 bits of fraction. Additional 156 Altitude Types MAY be assigned by IANA. The "floors" Altitude Type 157 is provided because altitude in meters may not be known within a 158 building, and a floor indication may be more useful. 160 GPS systems today can use WGS84 for horizontal and vertical datums, 161 [6] defines WGS84 as a three-dimensional datum. For other datum 162 values that do not include a vertical component, both the horizontal 163 and vertical datum of reference will be specified in the IANA 164 record. 166 Each of these 3 elements is preceded by an accuracy sub-field of 6 167 bits, indicating the number of bits of resolution. This resolution 168 sub-field accommodates the desire by some to easily adjust 169 the precision of a reported location. Contents beyond the claimed 170 resolution MAY be randomized to obscure greater precision that might 171 be available. 173 2. DHC Location Configuration Information Elements 175 DHCP is a binary Protocol; using protocols of LCI are likely to be 176 text based. Since most coordinate systems translate fairly easily 177 between binary-based and text-based location output (even emergency 178 services within the US), translation/conversion is a non-issue with 179 DHCP's binary format. 181 This binary format provides a fortunate benefit in a mechanism for 182 making a true/correct location coordinate imprecise. It further 183 provides the capability to have this binary representation be 184 deterministically imprecise. 186 The LCI format is as follows: 188 0 1 2 3 189 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 | Code TBD | 16 | LaRes | Latitude + 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | Latitude (cont'd) | LoRes | + 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | Longitude | 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 197 | AT | AltRes | Altitude | 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 | Alt (cont'd) | Datum | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 2.1 Elements of the Location Configuration Information 204 Code TBD: The code for this DHCP option. 206 16: The length of this option is 16 bytes. 208 LaRes: Latitude resolution. 6 bits indicating the number 209 of valid bits in the fixed-point value of Latitude. 211 This value is the number of high-order Latitude bits that should be 212 considered valid. Any bits entered to the right of this limit 213 should not be considered valid and might be purposely false, or 214 zeroed by the sending. 216 The examples below in section 4.0, are to illustrate that a smaller 217 value in the resolution field increases the area within which the 218 device is located). 220 LaRes does not define how Geographic Privacy policy should relate to 221 precision. 223 Values of resolution above decimal 34 are Undefined and reserved 224 because that is the largest number of bits in the Latitude field. 226 Latitude: a 34 bit fixed point value consisting of 9 bits of integer 227 and 25 bits of fraction. Latitude SHOULD be normalized to 228 within +/- 90 degrees. Positive numbers are north of the 229 equator and negative numbers are south of the equator. 231 A value of 2 in the LaRes field indicates a precision of no greater 232 than 1/6th that of the globe (detailed in the first example in 233 section 4.0). A value of 34 in the LaRes field indicates a 234 precision of about 3.11 mm in Latitude at the equator. 236 LoRes: Longitude resolution. 6 bits indicating the number of 237 valid bits in the fixed-point value of Longitude. 239 This value is the number of high-order Longitude bits that should be 240 considered valid. Any bits entered to the right of this limit 241 should not be considered valid and might be purposely false, or 242 zeroed by the sending. 244 LoRes does not define how Geographic Privacy policy should relate to 245 precision. 247 Values above decimal 34 are undefined and reserved. 249 Longitude: a 34 bit fixed point value consisting of 9 bits of 250 integer and 25 bits of fraction. Longitude SHOULD be 251 normalized to within +/- 180 degrees. Positive values are 252 East of the prime meridian and negative (2s complement) 253 numbers are West of the prime meridian. 255 A value of 2 in the LoRes field indicates precision of no greater 256 than 1/6th that of the globe (see first example in section 4.0). A 257 value of 34 in the LoRes field indicates a precision of about 258 2.42 mm in longitude (at the equator). Because lines of longitude 259 converge at the poles, the distance is smaller (better precision) 260 for locations away from the equator. 262 Altitude: A 30 bit value defined by the AT field 264 AltRes: Altitude resolution. 6 bits indicating the number of valid 265 bits in the altitude. Values above 30 (decimal) are 266 undefined and reserved. 268 AltRes does not define how Geographic Privacy policy should relate 269 to precision. 271 AT: Altitude Type for altitude. Codes defined are: 273 1: Meters - in 2s-complement fixed-point 22-bit integer part with 274 8-bit fraction 276 If AT = 1, an AltRes value 0.0 would indicate unknown altitude. 277 The most precise Altitude would have an AltRes value of 30. Many 278 values of AltRes would obscure any variation due to vertical datum 279 differences. 281 2: Floors - in 2s-complement fixed-point 22-bit integer part with 282 8-bit fraction 284 AT = 2 for Floors enables representing altitude in a form more 285 relevant in buildings which have different floor-to-floor 286 dimensions. An altitude coded as AT=2, AltRes = 30, and Altitude = 287 0.0 is meaningful even outside a building, and represents ground 288 level at the given latitude and longitude. Inside a building, 0.0 289 represents the floor level associated with ground level at the main 290 entrance. This document defines a number; one must arrive at the 291 number by counting floors from the floor defined to be 0.0. 293 The values represented by this AT will be of local significance. 294 Since buildings and floors can vary due to lack of common control, 295 the values chosen to represent the characteristics of an individual 296 building will be derived and agreed upon by the operator of the 297 building and the intended users of the data. Attempting to 298 standardize this type of function is beyond the scope this document. 300 Sub-floors can be represented by non-integer values. Example: a 301 mezzanine between floor 1 and floor 2 could be represented as a 302 value=1.1. Example: (2) mezzanines between floor 4 and floor 5 303 could be represented as values=4.1 and 4.2 respectively. 305 Floors located below ground level could be represented by negative 306 values. 308 Larger values represent floors that are above (higher in altitude) 309 floors with lower values. 311 The AltRes field SHOULD be set to maximum precision when AT = 2 312 (floors) when a floor value is included in the DHCP Reply, or 313 the AT = 0 to denote the floor isn't known. 315 Any additional LCI Altitude Types(s) to be defined for use via 316 this DHC Option MUST be done through a Standards Track RFC. 318 Datum: The Map Datum used for the coordinates given in this Option 320 The datum must include both a horizontal and a vertical reference. 321 Since the WGS 84 reference datum is three-dimensional, it includes 322 both. For any additional datum parameters, the datum codepoint must 323 specify both horizontal datum and vertical datum references. 325 The Datum byte has 256 possibilities, of which 3 are to be 326 registered with IANA by this document (all derived from 327 specification in [5]): 329 1: WGS 84 (Geographical 3D) - World Geodesic System 1984, CRS 330 Code 4327, Prime Meridian Name: Greenwich 332 2: NAD83 - North American Datum 1983, CRS Code 4269, Prime 333 Meridian Name: Greenwich; The associated vertical 334 datum is the North American Vertical Datum of 1988 335 (NAVD88) 336 This datum pair to be used when referencing 337 locations on land, not near tidal water (which would 338 use Datum = 3 below) 340 3: NAD83 - North American Datum 1983, CRS Code 4269, Prime 341 Meridian Name: Greenwich; The associated vertical 342 datum is Mean Lower Low Water (MLLW) 344 This datum pair to be used when referencing 345 locations on water/sea/ocean 347 Any additional LCI datum(s) to be defined for use via this DHC 348 Option MUST be done through a Standards Track RFC. 350 3. Security Considerations 352 Where critical decisions might be based on the value of this 353 GeoLoc option, DHCP authentication in [4] SHOULD be used to 354 protect the integrity of the DHCP options. 356 Since there is no privacy protection for DHCP messages, an 357 eavesdropper who can monitor the link between the DHCP server and 358 requesting client can discover this LCI. 360 To minimize the unintended exposure of location information, the LCI 361 option SHOULD be returned by DHCP servers only when the DHCP client 362 has included this option in its 'parameter request list' (section 363 3.5 [1]). 365 When implementing a DHC server that will serve clients across an 366 uncontrolled network, one should consider the potential security 367 risks. 369 4. IANA Considerations 371 IANA has assigned a DHCP option code of TBD for the GeoLoc option 372 defined in this document. 374 The GeoLoc Option defines two fields for which IANA is to maintain 375 a registry: The Altitude (AT) field (see Section 2) and the Datum 376 field (see Section 2). The datum indicator MUST include 377 specification of both horizontal and vertical datum. New values 378 for the Altitude (AT) field are assigned through "Standards Action" 379 [RFC 2434]. The initial values of the Altitude registry are as 380 follows: 382 AT = 1 meters of Altitude defined by the vertical datum 383 specified. 385 AT = 2 building Floors of Altitude. 387 Datum = 1 denotes the vertical datum WGS 84 as defined by the 388 EPSG as their CRS Code 4327; CRS Code 4327 also specifies 389 WGS 84 as the vertical datum 391 Datum = 2 denotes the vertical datum NAD83 as defined by the 392 EPSG as their CRS Code 4269; North American Vertical Datum 393 of 1988 (NAVD88) is the associated vertical datum for NAD83 395 Datum = 3 denotes the vertical datum NAD83 as defined by the 396 EPSG as their CRS Code 4269; Mean Lower Low Water (MLLW) is 397 the associated vertical datum for NAD83 399 Any additional LCI datum(s) to be defined for use via this DHC 400 Option MUST be done through a Standards Track RFC. 402 5. Acknowledgements 404 The authors would like to thank Patrik Falstrom, Ralph Droms, Ted 405 Hardie, Jon Peterson and Nadine Abbott for their inputs and 406 constructive comments regarding this document. Additionally, the 407 authors would like to thank Greg Troxel for the education on 408 vertical datums, and to Carl Reed. 410 Appendix: Calculations of Imprecision possible with the DHC LCI 412 The following examples for two different locations demonstrate 413 how the Resolution values for Latitude, Longitude and Altitude 414 can be used. In both examples the geo-location values were derived 415 from maps using the WGS84 map datum, therefore in these examples, 416 the datum field would have a value = 1 (00000001, or 0x01). 418 A.1 Location Configuration Information of "White House" (Example 1) 420 The address was NOT picked for any political reason and can 421 easily be found on the Internet or mapping software, but was 422 picked as an easily identifiable location on our planet. 424 Postal Address: 425 White House 426 1600 Pennsylvania Ave. NW 427 Washington, DC 20006 429 Standing on the sidewalk, north side of White House, between 430 driveways. 432 Latitude 38.89868 degrees North (or +38.89868 degrees) 433 Using 2s complement, 34 bit fixed point, 25 bit fraction 434 Latitude = 0x04dcc1fc8, 435 Latitude = 0001001101110011000001111111001000 437 Longitude 77.03723 degrees West (or -77.03723 degrees) 438 Using 2s complement, 34 bit fixed point, 25 bit fraction 439 Longitude = 0xf65ecf031, 440 Longitude = 1101100101111011001111000000110001 442 Altitude 15 444 In this example we are not inside a structure, therefore we will 445 assume an altitude value of 15 meters, interpolated from the US 446 Geological survey map, Washington West quadrangle. 448 AltRes = 30, 0x1e, 011110 449 AT = 1, 0x01, 000001 450 Altitude = 15, 0x0F00, 00000000000000000000000001111100000000 452 If: LaRes is expressed as value 2 (0x02 or 000010) and LoRes is 453 expressed as value 2 (0x02 or 000010), then it would describe a 454 geo-location region that is north of the equator and extends 455 from -1 degree (west of the meridian) to -128 degrees. This 456 would include the area from approximately 600km south of 457 Saltpond, Ghana, due north to the North Pole and approximately 458 4400km south-southwest of Los Angeles, CA due north to the North 459 Pole. This would cover an area of about one-sixth of the globe, 460 approximately 20 million square nautical miles (nm). 462 If: LaRes is expressed as value 3 (0x03 or 000011) and LoRes is 463 expressed as value 3, (0x03 or 000011) then it would describe a 464 geo-location area that is north from the equator to 63 degrees 465 north, and -65 degrees to -128 degrees longitude. This area 466 includes south of a line from Anchorage, AL to eastern Nunavut, 467 CN. and from the Amazons of northern Brazil to approximately 468 4400km south-southwest of Los Angeles, CA. This area would 469 include North America, Central America, and parts of Venezuela 470 and Columbia, except portions of Alaska and northern and eastern 471 Canada, approximately 10 million square nm. 473 If: LaRes is expressed as value 5 (0x05 or 000101) and LoRes is 474 expressed as value 5 (0x05 or 000101), then it would describe a 475 geo-location area that is latitude 32 north of the equator to 476 latitude 48 and extends from -64 degrees to -80 degrees 477 longitude. This is approximately an east-west boundary of a 478 time zone, an area of approximately 700,000 square nm. 480 If: LaRes is expressed as value 9 (0x09 or 001001) and LoRes is 481 expressed as value 9 (0x09 or 001001), which includes all the 482 integer bits, then it would describe a geo-location area that is 483 latitude 38 north of the equator to latitude 39 and extends from 484 -77 degrees to -78 degrees longitude. This is an area of 485 approximately 9600 square km (111.3km x 86.5km). 487 If: LaRes is expressed as value 18 (0x12 or 010010) and LoRes is 488 expressed as value 18 (0x12 or 010010), then it would describe a 489 geo-location area that is latitude 38.8984375 north to latitude 490 38.9003906 and extends from -77.0390625 degrees to -77.0371094 491 degrees longitude. This is an area of approximately 36,600 492 square meters (169m x 217m). 494 If: LaRes is expressed as value 22 (0x16 or 010110) and LoRes is 495 expressed as value 22 (0x16 or 010110), then it would describe a 496 geo-location area that is latitude 38.896816 north to latitude 497 38.8985596 and extends from -77.0372314 degrees to -77.0371094 498 degrees longitude. This is an area of approximately 143 square 499 meters (10.5m x 13.6m). 501 If: LaRes is expressed as value 28 (0x1c or 011100) and LoRes is 502 expressed as value 28 (0x1c or 011100), then it would describe a 503 geo-location area that is latitude 38.8986797 north to latitude 504 38.8986816 and extends from -77.0372314 degrees to -77.0372296 505 degrees longitude. This is an area of approximately 339 square 506 centimeters (20.9cm x 16.23cm). 508 If: LaRes is expressed as value 30 (0x1e or 011110) and LoRes is 509 expressed as value 30 (0x1e or 011110), then it would describe a 510 geo-location area that is latitude 38.8986797 north to latitude 511 38.8986802 and extends from -77.0372300 degrees to -77.0372296 512 degrees longitude. This is an area of approximately 19.5 square 513 centimeters (50mm x 39mm). 515 If: LaRes is expressed as value 34 (0x22 or 100010) and LoRes is 516 expressed as value 34 (0x22 or 100010), then it would describe a 517 geo-location area that is latitude 38.8986800 north to latitude 518 38.8986802 and extends from -77.0372300 degrees to -77.0372296 519 degrees longitude. This is an area of approximately 7.5 square 520 millimeters (3.11mm x 2.42mm). 522 In the (White House) example, the requirement of emergency 523 responders in North America via their NENA Model Legislation [8], 524 could be met by a LaRes value of 21 and a LoRes value of 20. 525 This would yield a geo-location that is latitude 38.8984375 north 526 to latitude 38.8988616 north and longitude -77.0371094 to 527 longitude -77.0375977. This is an area of approximately 89 feet 528 by 75 feet or 6669 square feet, which is very close to the 7000 529 square feet asked for by NENA. In this example a service 530 provider could enforce that a device send a Location 531 Configuration Information with this minimum amount of resolution 532 for this particular location when calling emergency services. 534 A.2 Location Configuration Information of "Sears Tower" (Example 2) 536 Postal Address: 537 Sears Tower 538 103rd Floor 539 233 S. Wacker Dr. 540 Chicago, IL 60606 542 Viewing the Chicago area from the Observation Deck of the Sears 543 Tower. 545 Latitude 41.87884 degrees North (or +41.87884 degrees) 546 Using 2s complement, 34 bit fixed point, 25 bit fraction 547 Latitude = 0x053c1f751, 548 Latitude = 0001010011110000011111011101010001 550 Longitude 87.63602 degrees West (or -87.63602 degrees) 551 Using 2s complement, 34 bit fixed point, 25 bit fraction 552 Longitude = 0xf50ba5b97, 553 Longitude = 1101010000101110100101101110010111 555 Altitude 103 557 In this example we are inside a structure, therefore we will 558 assume an altitude value of 103 to indicate the floor we are on. 559 The Altitude Type value is 2 indicating floors. The AltRes 560 field would indicate that all bits in the Altitude field are 561 true, as we want to accurately represent the floor of the 562 structure where we are located. 564 AltRes = 30, 0x1e, 011110 565 AT = 2, 0x02, 000010 566 Altitude = 103, 0x00006700, 000000000000000110011100000000 568 For the accuracy of the latitude and longitude, the best 569 information available to us was supplied by a generic mapping 570 service that shows a single geo-loc for all of the Sears Tower. 571 Therefore we are going to show LaRes as value 18 (0x12 or 010010) 572 and LoRes as value 18 (0x12 or 010010). This would be describing 573 a geo-location area that is latitude 41.8769531 to latitude 574 41.8789062 and extends from -87.6367188 degrees to -87.6347657 575 degrees longitude. This is an area of approximately 373412 576 square feet (713.3 ft. x 523.5 ft.). 578 6. Normative References 580 [1] Droms R., "Dynamic Host Configuration Protocol", RFC 2131, 581 March 1997 583 [2] Patrick M., "DHCP Relay Agent Information Option", RFC 3046, 584 January 2001 586 [3] Bradner S., "Key words for use in RFCs to Indicate Requirement 587 Levels", RFC 2119, March 1997 589 [4] Droms R., "Authentication for DHCP Messages", RFC 3118, June 590 2001 592 [5] European Petroleum Survey Group, http://www.epsg.org/ and 593 http://www.ihsenergy.com/epsg/geodetic2.html 595 [6] World Geodetic System 1984 (WGS 84), MIL-STD-2401, 596 http://164.214.2.59/publications/specs/printed/WGS84/wgs84.html 597 and http://www.wgs84.com/ 599 7. Informational References 601 [7] Farrell C., Schulze M., Pleitner S. and Baldoni D., "DNS 602 Encoding of Geographical Location", RFC 1712, November 1994. 604 [8] National Emergency Number Association (NENA) www.nena.org 605 NENA Technical Information Document on Model Legislation 606 Enhanced 911 for Multi-Line Telephone Systems 607 (http://www.nena.org/9%2D1%2D1techstandards/TechInfoDocs/ 608 MLTS_ModLeg_Nov200.PDF) 610 8. Author Information 612 James M. Polk 613 Cisco Systems 614 2200 East President George Bush Turnpike 615 Richardson, Texas 75082 USA jmpolk@cisco.com 617 John Schnizlein 618 Cisco Systems 619 9123 Loughran Road 620 Fort Washington, MD 20744 USA john.schnizlein@cisco.com 622 Marc Linsner 623 Cisco Systems 624 Marco Island, FL 34145 USA marc.linsner@cisco.com 626 Intellectual Property Statement 628 The IETF takes no position regarding the validity or scope of any 629 intellectual property or other rights that might be claimed to 630 pertain to the implementation or use of the technology described in 631 this document or the extent to which any license under such rights 632 might or might not be available; neither does it represent that it 633 has made any effort to identify any such rights. Information on the 634 IETF's procedures with respect to rights in standards-track and 635 standards-related documentation can be found in BCP-11. Copies of 636 claims of rights made available for publication and any assurances 637 of licenses to be made available, or the result of an attempt made 638 to obtain a general license or permission for the use of such 639 proprietary rights by implementers or users of this specification 640 can be obtained from the IETF Secretariat. 642 The IETF invites any interested party to bring to its attention any 643 copyrights, patents or patent applications, or other proprietary 644 rights which may cover technology that may be required to practice 645 this standard. Please address the information to the IETF Executive 646 Director. 648 Full Copyright Statement 650 "Copyright (C) The Internet Society (February 23rd, 2001). 651 All Rights Reserved. 653 This document and translations of it may be copied and furnished 654 to others, and derivative works that comment on or otherwise 655 explain it or assist in its implementation may be prepared, 656 copied, published and distributed, in whole or in part, without 657 restriction of any kind, provided that the above copyright notice 658 and this paragraph are included on all such copies and derivative 659 works. However, this document itself may not be modified in any 660 way, such as by removing the copyright notice or references to 661 the Internet Society or other Internet organizations, except as 662 needed for the purpose of developing Internet standards in which 663 case the procedures for copyrights defined in the Internet 664 Standards process must be followed, or as required to translate 665 it into languages other than English. 667 The limited permissions granted above are perpetual and will not 668 be revoked by the Internet Society or its successors or assigns. 670 This document and the information contained herein is provided on 671 an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET 672 ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR 673 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE 674 OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY 675 IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR 676 PURPOSE." 678 The Expiration date for this Internet Draft is: 680 June 8th, 2004