draft-ietf-geopriv-dhcp-lci-option-00.txt   draft-ietf-geopriv-dhcp-lci-option-01.txt 
Internet Engineering Task Force J. Polk Internet Engineering Task Force J. Polk
Internet Draft J. Schnizlein Internet Draft J. Schnizlein
Expiration: Nov 13th, 2003 M. Linsner Expiration: Dec 16th, 2003 M. Linsner
File: draft-ietf-geopriv-dhcp-lci-option-00.txt Cisco Systems File: draft-ietf-geopriv-dhcp-lci-option-01.txt Cisco Systems
Location Configuration Information for GEOPRIV Location Configuration Information for GEOPRIV
May 13th, 2003 June 16th, 2003
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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This document specifies a Dynamic Host Configuration Protocol Option This document specifies a Dynamic Host Configuration Protocol Option
for the geographic location of the client. The Location for the geographic location of the client. The Location
Configuration Information (LCI) includes latitude, longitude, and Configuration Information (LCI) includes latitude, longitude, and
altitude, with resolution indicators for each, as well as for the altitude, with resolution indicators for each, as well as for the
datum of the location. datum of the location.
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Conventions . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Conventions . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Rationale . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Rationale . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Changes from version -00 . . . . . . . . . . . . . . . . 4
2. Location Configuration Information (LCI) Elements . . . . . . 4 2. Location Configuration Information (LCI) Elements . . . . . . 4
2.1 Elements of the Location Configuration Information . . . 5 2.1 Elements of the Location Configuration Information . . . 5
3. Purpose of Resolution Value per La/Lo/Alt Element . . . . . . 7 3. Purpose of Resolution Value per La/Lo/Alt Element . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. Author Information . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Author Information . . . . . . . . . . . . . . . . . . . . . 9
Appendix Calculations of Imprecision possible with the DHC LCI . 10 Appendix Calculations of Imprecision possible with the DHC LCI . 10
A.1 LCI of "White House" (Example 1) . . . . . . . . . . . . 10 A.1 LCI of "White House" (Example 1) . . . . . . . . . . . . 10
A.2 LCI of "Sears Tower" (Example 2) . . . . . . . . . . . . 12 A.2 LCI of "Sears Tower" (Example 2) . . . . . . . . . . . . 12
8. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13 9. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13
1.0 Introduction 1. Introduction
This document specifies a Dynamic Host Configuration Protocol [1] This document specifies a Dynamic Host Configuration Protocol [1]
Option for the geographic location of the client, to be provided by Option for the geographic location of the client, to be provided by
the server. the server.
The DHCP server is assumed to have determined the location from the The DHCP server is assumed to have determined the location from the
Circuit-ID Relay Agent Information Option (RAIO) defined (as SubOpt Circuit-ID Relay Agent Information Option (RAIO) defined (as SubOpt
1) in [2]. In order to translate the circuit (switch port 1) in [2]. In order to translate the circuit (switch port
identifier) into a location, the DHCP server is assumed to have identifier) into a location, the DHCP server is assumed to have
access to a service that maps from circuit-ID to the location at access to a service that maps from circuit-ID to the location at
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is often the relevant location information, and not necessarily is often the relevant location information, and not necessarily
computable from meters of altitude. computable from meters of altitude.
Each of these 3 variables is preceded by an accuracy sub-field of 6 Each of these 3 variables is preceded by an accuracy sub-field of 6
bits, indicating the number of bits of resolution. This resolution bits, indicating the number of bits of resolution. This resolution
sub-field accommodates the GEOPRIV requirement [3] to easily adjust sub-field accommodates the GEOPRIV requirement [3] to easily adjust
the precision of a reported location. Contents beyond the claimed the precision of a reported location. Contents beyond the claimed
resolution MAY be randomized to obscure greater precision that might resolution MAY be randomized to obscure greater precision that might
be available. be available.
2.0 DHC Location Configuration Information Elements 1.4 Changes from version -00
Here is a list of changes to version -01 from -00:
- inadvertently left out the Acknowledgements section; corrected
that error
- added the NAD83 Datum to the list in section 2.1, and to the list
put forth for IANA registration
2. DHC Location Configuration Information Elements
DHCP is a binary Protocol; GEOPRIV is text-based. Most coordinate DHCP is a binary Protocol; GEOPRIV is text-based. Most coordinate
systems translate fairly easily between binary-based and text-based systems translate fairly easily between binary-based and text-based
location output (i.e. even emergency services within the US). The location output (i.e. even emergency services within the US). The
authors believe translation/conversion is a non-issue with DHCP's authors believe translation/conversion is a non-issue with DHCP's
binary format. binary format.
This binary format provides a fortunate benefit in a mechanism for This binary format provides a fortunate benefit in a mechanism for
making a true/correct location coordinate imprecise. It further making a true/correct location coordinate imprecise. It further
provides the capability to have this binary representation be provides the capability to have this binary representation be
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dimensions. An altitude coded as MU=2, AltRes = 30, and Altitude = dimensions. An altitude coded as MU=2, AltRes = 30, and Altitude =
0, represents the ground level outside as well as the ground floor 0, represents the ground level outside as well as the ground floor
within a building). This encoding is useful where the precise within a building). This encoding is useful where the precise
altitude is less important than the location at ground level. altitude is less important than the location at ground level.
Any additional Geopriv Measurement Unit(s) to be defined for use via Any additional Geopriv Measurement Unit(s) to be defined for use via
this DHC Option MUST be done through a Standards Track RFC. this DHC Option MUST be done through a Standards Track RFC.
Datum: The Map Datum used for the coordinates given in this Option Datum: The Map Datum used for the coordinates given in this Option
The Datum byte has 255 possibilities, of which 3 are to be The Datum byte has 255 possibilities, of which 4 are to be
registered with IANA by this document (all derived from registered with IANA by this document (all derived from
specification in [8]): specification in [8]):
1: WGS 84 (Geographical 3D) - World Geodesic System 1984, CRS 1: WGS 84 (Geographical 3D) - World Geodesic System 1984, CRS
Code 4327, Prime Meridian Name: Greenwich Code 4327, Prime Meridian Name: Greenwich
2: ED50 - European Datum 1950(77), CRS Code 4154, Prime Meridian 2: ED50 - European Datum 1950(77), CRS Code 4154, Prime Meridian
Name: Greenwich Name: Greenwich
3: ED87 - European Datum 1987, CRS Code 4231, Prime Meridian 3: ED87 - European Datum 1987, CRS Code 4231, Prime Meridian
Name: Greenwich Name: Greenwich
4: NAD83 - North American Datum 1983, CRS Code 4269, Prime
Meridian Name: Greenwich
Any additional Geopriv datum(s) to be defined for use via this DHC Any additional Geopriv datum(s) to be defined for use via this DHC
Option MUST be done through a Standards Track RFC. Option MUST be done through a Standards Track RFC.
3.0 Purpose of Resolution Value per La/Lo/Alt Element 3. Purpose of Resolution Value per La/Lo/Alt Element
GEOPRIV specified [3] the requirement that any location expressed GEOPRIV specified [3] the requirement that any location expressed
from or proxied on behalf of a device through the GEOPRIV Protocol from or proxied on behalf of a device through the GEOPRIV Protocol
can have the accuracy or precision of that device's location can have the accuracy or precision of that device's location
limited. The owner of the device, or the domain of the device limited. The owner of the device, or the domain of the device
determines the policy for divulging how precise the location is for determines the policy for divulging how precise the location is for
any/all given requesters of that device's location. any/all given requesters of that device's location.
One aspect within the GEOPRIV WG is the precision of a device's One aspect within the GEOPRIV WG is the precision of a device's
ability to present its location coordinates might have a domain ability to present its location coordinates might have a domain
policy override the individual policy in the sense of maximum policy override the individual policy in the sense of maximum
resolution possible. In other words, a user of a device might not resolution possible. In other words, a user of a device might not
mind providing a quite precise location return to a location mind providing a quite precise location return to a location
request, but the local domain might not want that level of precision request, but the local domain might not want that level of precision
by its policy. In this case, the resolution value provided in the by its policy. In this case, the resolution value provided in the
DHCP Reply can set this maximum precision value, perhaps allowing DHCP Reply can set this maximum precision value, perhaps allowing
the user of the Target device to make the values more imprecise the user of the Target device to make the values more imprecise
based on who is requesting their location. The document does not go based on who is requesting their location. The document does not go
further down this thought for good reason. further down this thought for good reason.
4.0 Security Considerations 4. Security Considerations
Where critical decisions might be based on the value of this Where critical decisions might be based on the value of this
GeoLoc option, DHCP authentication in [7] SHOULD be used to GeoLoc option, DHCP authentication in [7] SHOULD be used to
protect the integrity of the DHCP options. protect the integrity of the DHCP options.
5.0 IANA Considerations 5. IANA Considerations
The DHCP option code for the GeoLoc option is TBD. The DHCP option code for the GeoLoc option is TBD.
This document calls for the IANA registration of the following: This document calls for the IANA registration of the following:
MU = 1 is meters of Altitude from mean low tide. Semantics are MU = 1 is meters of Altitude from mean low tide. Semantics are
included in this document (section 2.1) included in this document (section 2.1)
MU = 2 is building Floors of Altitude. Semantics are included in MU = 2 is building Floors of Altitude. Semantics are included in
this document (section 2.1) this document (section 2.1)
Datum = 1 is denoting WGS 84 (Geographical 3D) as defined by the Datum = 1 is denoting WGS 84 (Geographical 3D) as defined by the
EPSG as their CRS Code 4327 EPSG as their CRS Code 4327
Datum = 2 is denoting ED50(77) as defined by the EPSG as their CRS Datum = 2 is denoting ED50(77) as defined by the EPSG as their CRS
Code 4154 Code 4154
Datum = 3 is denoting ED87 as defined by the EPSG as their CRS Code Datum = 3 is denoting ED87 as defined by the EPSG as their CRS Code
4231 4231
6.0 References Datum = 4 is denoting NAD83 as defined by the EPSG as their CRS Code
4269
6. Acknowledgements
The authors would like to thank Patrik Falstrom, Ralph Droms, Ted
Hardie and Nadine Abbott for their inputs and constructive comments
regarding this document, as well as the patience of the WG chairs.
7. References
[1] Droms R., "Dynamic Host Configuration Protocol", RFC 2131, [1] Droms R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997 March 1997
[2] Patrick M., "DHCP Relay Agent Information Option", RFC 3046, [2] Patrick M., "DHCP Relay Agent Information Option", RFC 3046,
January 2001 January 2001
[3] Cuellar J., Morris J., Mulligan D., "GEOPRIV Requirements", [3] Cuellar J., Morris J., Mulligan D., "GEOPRIV Requirements",
[4] Bradner S., "Key words for use in RFCs to Indicate Requirement [4] Bradner S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, March 1997 Levels", RFC 2119, March 1997
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Enhanced 911 for Multi-Line Telephone Systems Enhanced 911 for Multi-Line Telephone Systems
(http://www.nena.org/9%2D1%2D1techstandards/TechInfoDocs/ (http://www.nena.org/9%2D1%2D1techstandards/TechInfoDocs/
MLTS_ModLeg_Nov200.PDF) MLTS_ModLeg_Nov200.PDF)
[7] Droms R., "Authentication for DHCP Messages", RFC 3118, June [7] Droms R., "Authentication for DHCP Messages", RFC 3118, June
2001 2001
[8] European Petroleum Survey Group, http://www.epsg.org/ and [8] European Petroleum Survey Group, http://www.epsg.org/ and
http://www.ihsenergy.com/epsg/geodetic2.html http://www.ihsenergy.com/epsg/geodetic2.html
7.0 Author Information 8. Author Information
James M. Polk James M. Polk
Cisco Systems Cisco Systems
2200 East President George Bush Turnpike 2200 East President George Bush Turnpike
Richardson, Texas 75082 USA Richardson, Texas 75082 USA
jmpolk@cisco.com jmpolk@cisco.com
John Schnizlein John Schnizlein
Cisco Systems Cisco Systems
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geo-location area that is latitude 38.8986797 north to latitude geo-location area that is latitude 38.8986797 north to latitude
38.8986802 and extends from -77.0372300 degrees to -77.0372296 38.8986802 and extends from -77.0372300 degrees to -77.0372296
degrees longitude. This is an area of approximately 19.5 square degrees longitude. This is an area of approximately 19.5 square
centimeters (50mm x 39mm). centimeters (50mm x 39mm).
If: LaRes is expressed as value 34 (0x22 or 100010) and LoRes is If: LaRes is expressed as value 34 (0x22 or 100010) and LoRes is
expressed as value 34 (0x22 or 100010), then it would describe a expressed as value 34 (0x22 or 100010), then it would describe a
geo-location area that is latitude 38.8986800 north to latitude geo-location area that is latitude 38.8986800 north to latitude
38.8986802 and extends from -77.0372300 degrees to -77.0372296 38.8986802 and extends from -77.0372300 degrees to -77.0372296
degrees longitude. This is an area of approximately 7.5 square degrees longitude. This is an area of approximately 7.5 square
millimeters (3.11mm x 2.42mm).
In the (White House) example, the requirement of emergency In the (White House) example, the requirement of emergency
responders in North America via their NENA Model Legislation [6], responders in North America via their NENA Model Legislation [6],
could be met by a LaRes value of 21 and a LoRes value of 20. could be met by a LaRes value of 21 and a LoRes value of 20.
This would yield a geo-location that is latitude 38.8984375 north This would yield a geo-location that is latitude 38.8984375 north
to latitude 38.8988616 north and longitude -77.0371094 to to latitude 38.8988616 north and longitude -77.0371094 to
longitude -77.0375977. This is an area of approximately 89 feet longitude -77.0375977. This is an area of approximately 89 feet
by 75 feet or 6669 square feet, which is very close to the 7000 by 75 feet or 6669 square feet, which is very close to the 7000
square feet asked for by NENA. In this example a service square feet asked for by NENA. In this example a service
provider could enforce that a device send a Location provider could enforce that a device send a Location
Configuration Information with this minimum amount of resolution Configuration Information with this minimum amount of resolution
for this particular location when calling emergency services. for this particular location when calling emergency services.
A.2 Location Configuration Information of "Sears Tower" (Example 2) A.2 Location Configuration Information of "Sears Tower" (Example 2)
Postal Address: Postal Address:
Sears Tower Sears Tower
103th Floor 103rd Floor
233 S. Wacker Dr. 233 S. Wacker Dr.
Chicago, IL 60606 Chicago, IL 60606
Viewing the Chicago area from the Observation Deck of the Sears Viewing the Chicago area from the Observation Deck of the Sears
Tower. Tower.
Latitude 41.87884 degrees North (or +41.87884 degrees) Latitude 41.87884 degrees North (or +41.87884 degrees)
Using 2s complement, 34 bit fixed point, 25 bit fraction Using 2s complement, 34 bit fixed point, 25 bit fraction
Latitude = 0x053c1f751, Latitude = 0x053c1f751,
Latitude = 0001010011110000011111011101010001 Latitude = 0001010011110000011111011101010001
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For the accuracy of the latitude and longitude, the best For the accuracy of the latitude and longitude, the best
information available to us was supplied by a generic mapping information available to us was supplied by a generic mapping
service that shows a single geo-loc for all of the Sears Tower. service that shows a single geo-loc for all of the Sears Tower.
Therefore we are going to show LaRes as value 18 (0x12 or 010010) Therefore we are going to show LaRes as value 18 (0x12 or 010010)
and LoRes as value 18 (0x12 or 010010). This would be describing and LoRes as value 18 (0x12 or 010010). This would be describing
a geo-location area that is latitude 41.8769531 to latitude a geo-location area that is latitude 41.8769531 to latitude
41.8789062 and extends from -87.6367188 degrees to -87.6347657 41.8789062 and extends from -87.6367188 degrees to -87.6347657
degrees longitude. This is an area of approximately 373412 degrees longitude. This is an area of approximately 373412
square feet (713.3 ft. x 523.5 ft.). square feet (713.3 ft. x 523.5 ft.).
8. Full Copyright Statement 9. Full Copyright Statement
"Copyright (C) The Internet Society (February 23rd, 2001). "Copyright (C) The Internet Society (February 23rd, 2001).
All Rights Reserved. All Rights Reserved.
This document and translations of it may be copied and furnished This document and translations of it may be copied and furnished
to others, and derivative works that comment on or otherwise to others, and derivative works that comment on or otherwise
explain it or assist in its implementation may be prepared, explain it or assist in its implementation may be prepared,
copied, published and distributed, in whole or in part, without copied, published and distributed, in whole or in part, without
restriction of any kind, provided that the above copyright notice restriction of any kind, provided that the above copyright notice
and this paragraph are included on all such copies and derivative and this paragraph are included on all such copies and derivative
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This document and the information contained herein is provided on This document and the information contained herein is provided on
an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE
OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE." PURPOSE."
The Expiration date for this Internet Draft is: The Expiration date for this Internet Draft is:
Nov 13th, 2003 Dec 16th, 2003
 End of changes. 

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