GEOPRIV H. Schulzrinne
Internet-Draft Columbia U.
Expires: August 8, 2004 February 8, 2004
DHCP Option for Civil Addresses
draft-ietf-geopriv-dhcp-civil-01
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document specifies a Dynamic Host Configuration Protocol (DHCP)
option for the civil (country, street and community) location of the
client.
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Format of the DHCP Civil Location Option . . . . . . . . . . . 5
4. Civil Address Components . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
Normative References . . . . . . . . . . . . . . . . . . . . . 10
Informative References . . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 11
A. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . 13
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1. Terminology
In this document, the key words "MUST", "MUSTNOT", "REQUIRED",
"SHALL", "SHALLNOT", "SHOULD", "SHOULDNOT", "RECOMMENDED", "MAY", and
"OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
indicate requirement levels for compliant implementations.
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2. Introduction
Many end system services can benefit by knowing the approximate
location of the end device. In particular, IP telephony devices need
to know their location to contact the appropriate emergency response
agency and to be found by emergency responders.
There are two common ways to identify the location of an object,
either through geospatial coordinates or by so-called civil
coordinates. Geospatial coordinates indicate longitude, latitude and
altitude, while civil coordinates indicate a street address.
A related draft [6] describes a DHCP [2] option for conveying
geospatial information to a device. This draft describes how DHCP
can be used to convey the civil location to devices. Both can be
used simultaneously, increasing the chance to deliver accurate and
timely location information to emergency responders.
End systems that obtain location information via the mechanism
described here then use other protocol mechanisms to communicate this
information to the emergency call center.
Civil information is useful since it often provides additional,
human-usable information particularly within buildings. Also,
compared to geospatial information, it is readily obtained for most
occupied structures and can often be interpreted even if incomplete.
For example, for many large university or corporate campuses,
geocoding information to building and room granularity may not be
readily available.
Unlike geospatial information, the format for civil information
differs from country to country. Thus, this draft establishes an
IANA registry for civil location data fields. The initial set of
data fields is derived from standards published by the United States
National Emergency Numbering Association (NENA) [8]. It is
anticipated that other countries can reuse many of the data elements.
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3. Format of the DHCP Civil Location Option
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code TBD | N | Countrycode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| What | civil address elements ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Each civil address element has the following format:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAtype | CAlength | CAvalue ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code TBD: The code for this DHCP option is TBD by IANA.
N: The length of this option is variable.
Countrycode: The two-letter ISO 3166 country code in capital ASCII
letters, e.g., DE or US.
What: The 'what' element describes which location the DHCP refers to.
Currently, three options are defined: the location of the DHCP
server (0), the location of the network element believed to be
closest to the client (1) or the location of the client (2).
Option (2) SHOULD be used, but may not be known. Options (1) and
(2) SHOULDNOT be used unless it is known that the DHCP client is
in close physical proximity to the server or network element.
CAtype: A one-octet descriptor of the data civil address value.
CAlength: The length, in octets, of the CAvalue, not including the
CAlength field itself. Data SHOULD be encoded in uppercase.
CAvalue: The civil address value, encoded as UTF-8, and written in
uppercase letters where applicable.
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4. Civil Address Components
Since each country has different administrative hierarchies, with
often the same (English) names, this specification adopts a simple
hierarchical notation that is then instantiated for each country. We
assume that five levels are sufficient for sub-national divisions
above the street level.
All elements are OPTIONAL and can appear in any order. Abbreviations
do not need a trailing period.
+----------------------+----------------------+---------------------+
| CAtype | label | description |
+----------------------+----------------------+---------------------+
| 1 | A1 | national |
| | | subdivisions |
| | | (state, region, |
| | | province, |
| | | prefecture) |
| | | |
| 2 | A2 | county, parish, gun |
| | | (JP), district (IN) |
| | | |
| 3 | A3 | city, township, shi |
| | | (JP) |
| | | |
| 4 | A4 | city division, |
| | | borough, city |
| | | district, ward, |
| | | chou (JP) |
| | | |
| 5 | A5 | neighborhood, block |
| | | |
| 6 | A6 | street |
+----------------------+----------------------+---------------------+
Table 1
For specific countries, the administrative sub-divisions are
described below.
US (United States): The mapping to NENA designations is shown in
parentheses. A1=state (STA), using the the two-letter state and
possession abbreviations recommended by the United States Postal
Service Publication 28 [7], Appendix B; A2=county (CNA); A3=civil
community name (city or town) (MCN); A6=street (STN). A4 and A5
are not used. The civil community name (MCN) reflects the
political boundaries. These may differ from postal delivery
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assignments for historical or practical reasons.
CA (Canada): The mapping to NENA designations is shown in
parentheses. A1=province (STA), A2=county (CNA), A3=city or town
(MCN).
JP (Japan): A1=metropolis (To, Fu) or prefecture (Ken, Do); A2=city
(Shi) or rural area (Gun); A3=ward (Ku) or village (Mura); A4=town
(Chou or Machi); A5=city district (Choume); A6=block (Banchi or
Ban).
DE (Germany): A1=state (Bundesstaat); A2=county (Kreis); A3=city
(Stadt, Gemeinde); A6=street (Strasse).
Additional CA types appear in many countries and are simply omitted
where they are not needed:
+----------------+----------------+----------------+----------------+
| CAtypej | NENA | Description | Examples |
+----------------+----------------+----------------+----------------+
| 16 | PRD | leading street | N |
| | | direction | |
| | | | |
| 17 | POD | trailing | SW |
| | | street suffix | |
| | | | |
| 18 | STS | street suffix | AVE, PLATZ |
| | | | |
| 19 | HNO | house number | 123 |
| | | | |
| 20 | HNS | house number | A, 1/2 |
| | | suffix | |
| | | | |
| 21 | LMK | landmark or | SHADELAND |
| | | vanity address | CRESCENT APTS |
| | | | |
| 22 | LOC | additional | APT 17 |
| | | location | |
| | | information | |
| | | | |
| 23 | NAM | name | JOE'S |
| | | (residence and | BARBERSHOP |
| | | office | |
| | | occupant) | |
| | | | |
| 24 | ZIP | postal/zip | 10027-1234 |
| | | code | |
| | | | |
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| 25 | | type of place | |
| | | | |
| 26 | | floor | |
| | | | |
| 27 | | room number | |
+----------------+----------------+----------------+----------------+
The CA types labeled in the second column correspond to items from
the NENA "Recommended Formats & Protocols For ALI Data Exchange, ALI
Response & GIS Mapping" [8], but are applicable to most countries.
The "NENA" column refers to the data dictionary name in Exhibit 18 of
[8].
The NAM object is used to aid user location ("Joe Miller" "Alice's
Dry Cleaning"). It does not identify the person using a
communications device, but rather the person or organization
associated with the address.
For POD and PRD, in English-speaking countries, the abbreviations N,
E, S, W, and NE, NW, SE, SW should be used.
STS designates a street suffix. In the United States (US), the
abbreviations recommended by the United States Postal Service
Publication 28 [7], Appendix C, SHOULD be used.
The "type of place" item indicates whether the location is a 'home',
'office' or 'public', using text strings. Additional text strings
can be registered with IANA and correspond to the "placetype" element
in [9].
The "privacy" object can have the string values:
public: Others may be able to see or hear the communications.
private: Inappropriate individuals are not likely to see or hear the
communications.
quiet: The location is a place such as a library, restaurant,
place-of-worship, or theater that discourages noise, conversation
and other distractions.
Additional string values can be registered with IANA using the
registry established in [9].
The DHCP long-options mechanism described in RFC 3396 [3] MUST be
used if the civil address option exceeds the maximum DHCP option size
of 255 octets.
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5. Security Considerations
The information in this option may be used for a variety of tasks. In
some cases, integrity of the information may be of great importance.
In such cases, DHCP authentication in RFC3118 [4] SHOULD be used to
protect the integrity of the DHCP options.
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Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[3] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic
Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002.
[4] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
RFC 3118, June 2001.
[5] Sugano, H. and S. Fujimoto, "Presence Information Data Format
(PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May
2003.
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Informative References
[6] Polk, J., Schnizlein, J. and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based Location
Configuration Information",
draft-ietf-geopriv-dhcp-lci-option-03 (work in progress),
December 2003.
[7] United States Postal Service, "Postal Addressing Standards",
November 2000.
[8] National Emergency Number Assocation, "NENA Recommended Formats
and Protocols For ALI Data Exchange, ALI Response and GIS
Mapping", NENA NENA-02-010, January 2002.
[9] Schulzrinne, H., "RPID -- Rich Presence Information Data
Format", draft-ietf-simple-rpid-00 (work in progress), July
2003.
Author's Address
Henning Schulzrinne
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
US
Phone: +1 212 939 7042
EMail: hgs+simple@cs.columbia.edu
URI: http://www.cs.columbia.edu
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Appendix A. Acknowledgments
Rohan Mahy and Stefan Berger provided helpful comments.
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