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Versions: (draft-schulzrinne-geopriv-dhcp-civil) 00 01 02 03 04 05 06 07 08 09 RFC 4676

GEOPRIV                                                   H. Schulzrinne
Internet-Draft                                               Columbia U.
Expires: June 23, 2006                                 December 20, 2005


Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for Civic
                  Addresses Configuration Information
                    draft-ietf-geopriv-dhcp-civil-08

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   This Internet-Draft will expire on June 23, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document specifies a Dynamic Host Configuration Protocol (DHCPv4
   and DHCPv6) option containing the civic location of the client or the
   DHCP server.  The Location Configuration Information (LCI) includes
   information about the country, administrative units such as states,
   provinces and cities, as well as street addresses, postal community
   names and building information.  The option allows multiple
   renditions of the same address in different scripts and languages.




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Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Format of the DHCP Civic Location Option . . . . . . . . . . .  7
     3.1   Overall Format for DHCPv4  . . . . . . . . . . . . . . . .  7
     3.2   Overall Format for DHCPv6  . . . . . . . . . . . . . . . .  7
     3.3   Element Format . . . . . . . . . . . . . . . . . . . . . .  8
     3.4   Civic Address Components . . . . . . . . . . . . . . . . .  8
   4.  Postal Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
   5.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     8.1   Normative References . . . . . . . . . . . . . . . . . . . 20
     8.2   Informative References . . . . . . . . . . . . . . . . . . 21
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 21
   A.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 22
       Intellectual Property and Copyright Statements . . . . . . . . 23
































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1.  Terminology

   In this document, the key words "MUST", "MUSTNOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "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 civic
   addresses.  Geospatial coordinates indicate longitude, latitude and
   altitude, while civic addresses indicate a street address.

   The civic address is commonly, but not necessarily, closely related
   to the postal address, used by the local postal service to deliver
   mail.  However, not all postal addresses correspond to street
   addresses.  For example, the author's address is a postal address
   that does not appear on any street or building sign.  Naturally, post
   office boxes would be unsuitable for the purposes described here.
   The term 'civil address' or 'jurisdictional address' is also
   sometimes used instead of civic address.  This document mainly
   supports civic addresses, but allows to indicate the postal community
   name if it differs from the civic name.

   A related document [18] describes a DHCPv4 [2] option for conveying
   geospatial information to a device.  This draft describes how DHCPv4
   and DHCPv6 [6] can be used to convey the civic and postal address to
   devices.  Both geospatial and civic formats be used simultaneously,
   increasing the chance to deliver accurate and timely location
   information to emergency responders.

   This document only defines the delivery of location information from
   the DHCP server to the client, due to security concerns related to
   using DHCP to update the database.  Within the GEOPRIV architecture
   as defined by RFC 3693 [11], the defined mechanism in this document
   for conveying initial location information is known as a "sighting"
   function.  Sighting functions are not required to have security
   capabilities and are only intended to be configured in trusted and
   controlled environments.  (A classic example of the sighting function
   is a Global Positioning System wired directly to a network node.)
   After initial location information has been introduced, it MUST be
   afforded the protections defined in RFC 3694 [12].  Therefore,
   location information MUST NOT be sent from a DHCP client to a DHCP
   server as is normally allowed by DHCP.

   End systems that obtain location information via the mechanism
   described here then use other protocol mechanisms to communicate this
   information to an emergency call center or to convey it as part of
   presence information.



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   Civic 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 civic and postal
   information differs from country to country.  The initial set of data
   fields is derived from standards published by the United States
   National Emergency Number Association (NENA) [21] and takes into
   account addressing conventions for a number of countries in different
   areas of the world.  It is anticipated that other countries can reuse
   many of the data elements, but the draft also establishes an IANA
   registry for defining additional civic location data fields.

   The same civic and postal address information can often be rendered
   in multiple languages and scripts.  For example, Korean addresses are
   often shown in Hangul, Latin and Kanji, while some older cities have
   multiple language variants (Munich, Muenchen and Monaco, for
   example).  Since DHCPv4 and DHCPv6 do not currently support a
   mechanism to query for a specific script or language, the DHCP server
   SHOULD provide all common renderings to the client and MUST provide
   at least the rendering in the language and script appropriate to the
   location indicated.  For example, for use in presence information,
   the target may be visiting from a foreign country and want to convey
   the information in a format suitable for watchers in its home
   country.  For emergency services, the rendering in the local language
   is likely to be most appropriate.  To provide multiple renderings,
   the server repeats sequences of address elements, prefixing each with
   'language' and/or 'script' element (see Section 3.3).  The language
   and script remain in effect for subsequent elements until overridden
   by another language or script element.  Since the DHCP client is
   unlikely to be the final consumer of the location information, the
   DHCP server has to provide all appropriate language and script
   versions, which the client then passes on via some other GEOPRIV
   using protocol, typically encoded in a presence-based GEOPRIV
   location object format [19].

   The DHCP server MAY provide location information for multiple
   locations related to the target, for example, both the network
   element and the network jack itself.  This is likely to help in
   debugging network problems, for example.

   This document calls for various operational decisions.  For example,
   an administrator has to decide when to provide the location of the
   DHCP server or other network elements even if these may be a good



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   distance away from the client.  The administrator must also consider
   whether to include both civic and geospatial information if these may
   differ.  The document does not specify the criteria to be used in
   making these choices, as these choices are likely to depend strongly
   on local circumstances and need to be based on local, human
   knowledge.

   If a network provides civic location information via both DHCPv4 and
   DHCPv6, the information conveyed by two protocols MUST be the same.

   As discussed in Security Considerations (Section 6), the
   GEOCONF_CIVIC option SHOULD be returned by DHCPv4 servers only when
   the DHCPv4 client has included this option in its 'parameter request
   list' (RFC 2131 [2], Section 3.5).  Similarly, the
   OPTION_GEOCONF_CIVIC option SHOULD be returned by DHCPv6 servers only
   when the DHCPv6 client has included this option in its OPTION_ORO.

   The DHCPv4 long-options mechanism described in RFC 3396 [8] MUST be
   used if the civic address option exceeds the maximum DHCPv4 option
   size of 255 octets.































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3.  Format of the DHCP Civic Location Option

3.1  Overall Format for DHCPv4

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | GEOCONF_CIVIC |       N       |      what     |    country    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    code       |        civic address elements                ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Code GEOCONF_CIVIC: The code for this DHCP option is TBD by IANA.

   N: The length of this option is variable.  The minimum length is 3.

   what: The 'what' element describes which location the DHCP entry
      refers to.  Currently, three options are defined:  the location of
      the DHCP server (a value of 0), the location of the network
      element believed to be closest to the client (a value of 1) or the
      location of the client (a value of 2).  Option (2) SHOULD be used,
      but may not be known.  Options (0) and (1) SHOULD NOT be used
      unless it is known that the DHCP client is in close physical
      proximity to the server or network element.

   country code: The two-letter ISO 3166 country code in capital ASCII
      letters, e.g., DE or US.  (Civic addresses always contain country
      designations, suggesting the use of a fixed-format field to save
      space.)

   civic address elements: Zero or more elements comprising the civic
      and/or postal address, with the format described below
      (Section 3.3).


3.2  Overall Format for DHCPv6

   The DHCPv6 [6] civic address option refers generally to the client as
   a whole.












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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      OPTION_GEOCONF_CIVIC     |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      what     |        country code           |               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               .
   .                     civic address elements                    .
   .                              ...                              .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code: OPTION_GEOCONF_CIVIC (TBD)

   option-len: Length of the Countrycode, 'what' and civic address
      elements.

   what: See above (Section 3.1).

   country code: See above (Section 3.1).

   civic address elements: See above (Section 3.1).


3.3  Element Format

   For both DHCPv4 and DHCPv6, each civic 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                 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   CAtype: A one-octet descriptor of the data civic address value.

   CAlength: The length, in octets, of the CAvalue, not including the
      CAlength field itself.

   CAvalue: The civic address value, as described in detail below.


3.4  Civic 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



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   above the street level.

   All elements are OPTIONAL and can appear in any order.

   Component values MUST be encoded as UTF-8 [7].  They SHOULD be
   written in mixed case, following the customary spelling.  The script
   indication (CAtype=128) MUST be written in mixed-case, with the first
   letter a capital letter.

   Abbreviations MUST NOT be used unless indicated for each element.
   Abbreviations do not need a trailing period.

   It is RECOMMENDED that all elements in a particular script (CAtype
   128) and language (CAtype 0) be grouped together as that reduces the
   number of script and language identifiers needed.

   For each script and language, elements SHOULD be included in numeric
   order from lowest to highest of their CAtype.  In general, an element
   is labeled in its language and script by the most recent 'language
   tag' (CAtype = 0) element preceding it.  Since not all elements
   depend on the script and language, a client accumulates the elements
   by CAtype and then selects the most desirable language and script
   rendition if there are multiple elements for the same CAtype.

   +----------------------+----------------------+---------------------+
   | CAtype               | label                | description         |
   +----------------------+----------------------+---------------------+
   | 1                    | A1                   | national            |
   |                      |                      | subdivisions        |
   |                      |                      | (state, canton,     |
   |                      |                      | 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 |
   |                      |                      |                     |





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   | 6                    | A6                   | group of streets    |
   |                      |                      | below the           |
   |                      |                      | neighborhood level  |
   +----------------------+----------------------+---------------------+

                                  Table 1

   For specific countries, the administrative sub-divisions are
   described below.

   CA (Canada): The mapping to NENA designations is shown in
      parentheses.  A1 designates the province (STA), A2 the county
      (CNA), A3 the city or town (MCN).

   DE (Germany): A1 represents the state (Bundesstaat), A2 the county
      (Regierungsbezirk), A3 the city (Stadt, Gemeinde), A4 the district
      (Bezirk).  Street suffixes (STS) are used only for designations
      that are a separate word (e.g., Marienthaler Strasse).

   JP (Japan): A1 repreents the metropolis (To, Fu) or prefecture (Ken,
      Do), A2 the city (Shi) or rural area (Gun), A3 the ward (Ku) or
      village (Mura), A4 the town (Chou or Machi), A5 the city district
      (Choume) and A6 the block (Banchi or Ban).

   KR (Korea): A1 represents the province (Do), A2 the county (gun), A3
      the city or village (ri), A4 the urban district (gu), A5 a
      neighborhood (dong).

   US (United States): The mapping to NENA designations is shown in
      parentheses.  A1 designates the state (STA), using the the two-
      letter state and possession abbreviations recommended by the
      United States Postal Service Publication 28 [20], Appendix B.  A2
      designates the county, parish (Louisiana) or borough (Alaska)
      (CNA).  A3 designates the civic community name, e.g., city or
      town.  It is also known as the municipal jurisdiction.  (MCN) The
      optional element A4 contains the community place name, such as
      "New bope Community" or "Urbanizacion" in Puerto Rico.  The civic
      community name (MCN) reflects the political boundaries.  These
      boundaries may differ from postal delivery assignments, the postal
      community name (PCN), for historical or practical reasons.

   Mappings and considerations for additional countries should be
   written up in documents titled "Civic Addresses for [Country] (XY)",
   where "XY" represents the two-letter country code, e.g., "Civic
   Address Considerations for France (FR)".

   Additional CA types appear in many countries and are simply omitted
   where they are not needed or known:



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   +------------+------------+-------------+-------------+-------------+
   | CAtype     | NENA       | PIDF        | Description | Examples    |
   +------------+------------+-------------+-------------+-------------+
   | 0          |            |             | language    | i-default   |
   |            |            |             |             | [3]         |
   |            |            |             |             |             |
   | 16         | PRD        | PRD         | leading     | N           |
   |            |            |             | street      |             |
   |            |            |             | direction   |             |
   |            |            |             |             |             |
   | 17         | POD        | POD         | trailing    | SW          |
   |            |            |             | street      |             |
   |            |            |             | suffix      |             |
   |            |            |             |             |             |
   | 18         | STS        | STS         | street      | Ave, Platz  |
   |            |            |             | suffix or   |             |
   |            |            |             | type        |             |
   |            |            |             |             |             |
   | 19         | HNO        | HNO         | house       | 123         |
   |            |            |             | number      |             |
   |            |            |             |             |             |
   | 20         | HNS        | HNS         | house       | A, 1/2      |
   |            |            |             | number      |             |
   |            |            |             | suffix      |             |
   |            |            |             |             |             |
   | 21         | LMK        | LMK         | landmark or | Columbia    |
   |            |            |             | vanity      | University  |
   |            |            |             | address     |             |
   |            |            |             |             |             |
   | 22         | LOC        | LOC         | additional  | South Wing  |
   |            |            |             | location    |             |
   |            |            |             | information |             |
   |            |            |             |             |             |
   | 23         | NAM        | NAM         | name        | Joe's       |
   |            |            |             | (residence  | Barbershop  |
   |            |            |             | and office  |             |
   |            |            |             | occupant)   |             |
   |            |            |             |             |             |
   | 24         | ZIP        | PC          | postal/zip  | 10027-1234  |
   |            |            |             | code        |             |
   |            |            |             |             |             |
   | 25         |            |             | building    | Low Library |
   |            |            |             | (structure) |             |
   |            |            |             |             |             |
   | 26         |            |             | unit        | Apt 42      |
   |            |            |             | (apartment, |             |
   |            |            |             | suite)      |             |
   |            |            |             |             |             |



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   | 27         |            | FLR         | floor       | 4           |
   |            |            |             |             |             |
   | 28         |            |             | room number | 450F        |
   |            |            |             |             |             |
   | 29         |            |             | placetype   | office      |
   |            |            |             |             |             |
   | 30         | PCN        |             | postal      | Leonia      |
   |            |            |             | community   |             |
   |            |            |             | name        |             |
   |            |            |             |             |             |
   | 31         |            |             | post office | 12345       |
   |            |            |             | box (P.O.   |             |
   |            |            |             | Box)        |             |
   |            |            |             |             |             |
   | 32         |            |             | additional  | 13203000003 |
   |            |            |             | code        |             |
   |            |            |             |             |             |
   | 33         |            | SEAT        | seat (desk, | WS 181      |
   |            |            |             | cubicle,    |             |
   |            |            |             | workstation |             |
   |            |            |             | )           |             |
   |            |            |             |             |             |
   | 34         |            |             | Primary     | Broadway    |
   |            |            |             | road or     |             |
   |            |            |             | street      |             |
   |            |            |             |             |             |
   | 35         |            |             | Road        | 14          |
   |            |            |             | section     |             |
   |            |            |             |             |             |
   | 36         |            |             | Road branch | Lane 7      |
   |            |            |             |             |             |
   | 37         |            |             | Road        | Alley 8     |
   |            |            |             | sub-branch  |             |
   |            |            |             |             |             |
   | 38         |            |             | Street name | Old         |
   |            |            |             | pre-modifie |             |
   |            |            |             | r           |             |
   |            |            |             |             |             |
   | 39         |            |             | Street name | Service     |
   |            |            |             | post-modifi |             |
   |            |            |             | er          |             |
   |            |            |             |             |             |
   | 128        |            |             | script      | Latn        |
   |            |            |             |             |             |
   | 255        |            |             | reserved    |             |
   +------------+------------+-------------+-------------+-------------+

   The CA types labeled in the second column correspond to items from



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   the NENA "Recommended Formats & Protocols For ALI Data Exchange, ALI
   Response & GIS Mapping" [21], but are applicable to most countries.
   The "NENA" column refers to the data dictionary name in Exhibit 18 of
   [21].

   The column labeled PIDF indicates the element name from [19].  (Some
   elements were added to this document after the PIDF location object
   definition had been completed.  These elements currently do not have
   a PIDF-LO equivalent.)

   Language: The "language" item (CAtype 0) optionally identifies the
      language used for presenting the address information, drawing from
      the tags for identifying languages in [4], as discussed in [16].
      If omitted, the default value for this tag is "i-default" [3].

   Script: The "script" item (CAtype 128) optionally identifies the
      script used for presenting the address information, drawing from
      the tags for identifying scripts described in [15] and elaborated
      on in Section 2.2.3 of [16].  If omitted, the default value for
      this tag is "Latn".

   POD, PRD: The abbreviations N, E, S, W, and NE, NW, SE, SW SHOULD be
      used for POD (trailing street suffix) and PRD (leading street
      direction) in English-speaking countries.

   STS: STS designates a street suffix or type.  In the United States
      (US), the abbreviations recommended by the United States Postal
      Service Publication 28 [20], Appendix C, SHOULD be used.

   HNS: HNS ("house number") is a modifier to a street address; it does
      not identify parts of a street address.

   LMK: LMK ("landmark", CAtype 21) is a string name for a location.  It
      conveys the same information as the street address, but reflects
      common local designation of a structure, a group of buildings or a
      place that helps recipients locate the place.  For example, an
      industrial park may have a widely-recognized name that is more
      readily found than a single street address.  Some places, such as
      parks, may not have street names or house numbers and SHOULD be
      identified by a LMK string.  In addition, this component can be
      used to indicate where postal delivery locations differ from the
      jurisdictional one.

   LOC: LOC ("location", CAtype 22) is an unstructured string specifying
      additional information about the location, such as the part of a
      building or other unstructured information.





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   PCN: The postal community name (CAtype 30) and the post office box
      (CAtype 31) allow the recipient to construct a postal address.
      The post office box field should contain the words "P.O. Box" or
      other locally appropriate postal designation.

   NAM: 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.

   LMK: While a landmark (LMK, CAtype 21) can indicate a complex of
      buildings, 'building' (CAtype 25) conveys the name of a single
      building if the street address includes more than one building or
      the building name is helpful in identifying the location.  (For
      example, on university campuses, the house number is often not
      displayed on buildings, while the building name is prominently
      shown.)

   Unit: The 'unit' object (CAtype 26) contains the name or number of a
      part of a structure where there are separate administrative units,
      owners or tenants, such as separate companies or families who
      occupy that structure.  Common examples include suite or apartment
      designations.

   Room: A 'room' (CAtype 28) is the smallest identifiable subdivision
      of a structure.

   Type of place: The "type of place" item (CAtype 29) describes the
      type of place described by the civic coordinates.  For example, it
      describes whether it is a home, office, street or other public
      space.  The values are drawn from the items in the location types
      registry [14].  This information makes it easy, for example, for
      the DHCP client to then populate the presence information.  Since
      this is an IANA-registered token, the language and script
      designations do not apply for this element.

   Additional code: The "additional code" item (CAtype 32) provides an
      additional, country-specific code identifying the location.  For
      example, for Japan, it contains the Japan Industry Standard (JIS)
      address code.  The JIS address code provides a unique address
      inside of Japan, down to the level of indicating the floor of the
      building.

   SEAT: The "seat" item (CAtype 33) designates a place where a person
      might sit, such as a seat in a stadium or theater, or a cubicle in
      an open-plan office or a booth in a trade-show.





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   Primary road: The "primary road" item (CAtype 34) given to the road
      or street name associated with the address.  If CAtypes 35 through
      37 are not specified, the building or designated location is found
      on that street.  If some of CAtypes 35 through 37 are specified,
      this designates the main road, off of which the smaller streets
      branch off and where the structure or building is actually
      located.

   Road section: The "road section" item (CAtype 35) designates a
      specific section or stretch of a primary road.  This is a new
      thoroughfare element and is useful where a primary road is divided
      into sections that re-use the same street number ranges.

   Branch Road Name: The "branch road name" item (CAtype 36) represents
      the name or identifier of a road or street that intersects or is
      associated with a primary road.  The branch road name is only used
      in countries where side streets do not have unique names within a
      municipality or other administrative unit, but rather must be
      qualified by the name of the primary road name that they branch
      off of.

   Sub-Branch Road Name: The "sub-branch road name" (CAtype 37) item
      represents the name of a street that branches off a branch road
      (CAtype 36).  The sub-branch road name is only used in countries
      where such streets are named relative to the primary road name and
      branch road that they connect with.

   Street Name Pre-Modifier: The "street name pre-modifier" (CAtype 38)
      is an optional element of the complete street name.  It is a word
      or phrase that precedes all other elements of the street name and
      modifies it, but is separated from the street name by a street
      name pre-directional.  An example is "Old" in "Old North First
      Street".

   Street Name Post-Modifier: The "street name post-modifier" (CAtype
      39) is an optional element of the complete street name.  It is a
      word or phrase that follows all other elements of the street name
      and modifies it, but is separated from the street name by a street
      name post-directional and/or street suffix.  An example is
      "Extended" in "East End Avenue Extended".











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4.  Postal Addresses

   In general, a recipient can construct a postal address by using all
   language-appropriate elements, including the postal code (ZIP, CAtype
   24).  However, certain elements override the civic address components
   to create a postal address.  If the elments include a post office box
   (CAtype 31), the street address components (CAtype 34, PRD, POD, STS,
   HNO, HNS) are replaced with the post office box element.  If a postal
   community name is specified, the civic community name (typically, A3)
   is replaced by the postal community name (PCN, CAtype 30).  Country-
   specific knowledge is required to create a valid postal address.  The
   formating of such addresses is beyond the scope of this document.







































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5.  Example

   Rather than showing the precise byte layout of a DHCP option, we show
   a symbolic example below, representing the civic address of the
   Munich city hall in Bavaria, Germany.  The city and state name are
   also conveyed in English and Italian in addition to German; the other
   items are assumed to be common across all languages.  All languages
   use the latin script.

                    +--------+---------------------+
                    | CAtype | CAvalue             |
                    +--------+---------------------+
                    | 0      | de                  |
                    |        |                     |
                    | 128    | Latn                |
                    |        |                     |
                    | 1      | Bayern              |
                    |        |                     |
                    | 2      | Oberbayern          |
                    |        |                     |
                    | 3      | M=U+00FCnchen       |
                    |        |                     |
                    | 6      | Marienplatz         |
                    |        |                     |
                    | 19     | 8                   |
                    |        |                     |
                    | 21     | Rathaus             |
                    |        |                     |
                    | 24     | 80331               |
                    |        |                     |
                    | 29     | government-building |
                    |        |                     |
                    | 31     | Postfach 1000       |
                    |        |                     |
                    | 0      | en                  |
                    |        |                     |
                    | 1      | Bavaria             |
                    |        |                     |
                    | 3      | Munich              |
                    |        |                     |
                    | 0      | it                  |
                    |        |                     |
                    | 1      | Baviera             |
                    |        |                     |
                    | 3      | Monaco              |
                    +--------+---------------------+





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6.  Security Considerations

   The security considerations discussed in the GEOPRIV architecture
   defined by RFC 3693 [11] apply.

   Where critical decisions might be based on the value of this
   GEOCONF_CIVIC option, DHCPv4 authentication in RFC3118 [5] SHOULD be
   used to protect the integrity of the DHCP options.

   Since there is no privacy protection for DHCP messages, an
   eavesdropper who can monitor the link between the DHCP server and
   requesting client can discover the information contained in this
   option.  Thus, usage of this option on networks without access
   restrictions or network-layer or link-layer privacy mechanisms is NOT
   RECOMMENDED.

   To minimize the unintended exposure of location information, the
   GEOCONF_CIVIC option SHOULD be returned by DHCPv4 servers only when
   the DHCPv4 client has included this option in its 'parameter request
   list' (RFC 2131 [2], Section 3.5).  Similarly, the
   OPTION_GEOCONF_CIVIC option SHOULD be returned by DHCPv6 servers only
   when the DHCPv6 client has included this option in its OPTION_ORO.





























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7.  IANA Considerations

   This document requests that IANA register a new DHCPv4 and DHCPv6
   option code for the Civic Address (GEOCONF_CIVIC and
   OPTION_GEOCONF_CIVIC, respectively).

   This document establishes a new IANA registry for CAtypes designating
   civic address components.  According to RFC 2434 [17], this registry
   operates under the "Specification Required" rules.  The IANA
   registration needs to include the following information:

   CAtype: Numeric identifier, assigned by IANA.

   Brief description: Short description identifying the meaning of the
      element.

   Reference to published specification: A stable reference to an RFC or
      other permanent and readily available reference, in sufficient
      detail so that interoperability between independent
      implementations is possible.

   Country-specific considerations: If applicable, notes whether the
      element is only applicable or defined for certain countries.

   The initial list of registrations is contained in Section 3.4.

   Updates to country-specific considerations for previously-defined
   CAtypes are not defined by IANA registrations since they are
   descriptive, not a registration of identifiers.  As noted earlier,
   country-specific conventions are instead written up in documents
   titled "Civic Addresses for [Country] (XY)".




















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8.  References

8.1  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]   Alvestrand, H., "IETF Policy on Character Sets and Languages",
         BCP 18, RFC 2277, January 1998.

   [4]   Alvestrand, H., "Tags for the Identification of Languages",
         BCP 47, RFC 3066, January 2001.

   [5]   Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
         RFC 3118, June 2001.

   [6]   Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
         Carney, "Dynamic Host Configuration Protocol for IPv6
         (DHCPv6)", RFC 3315, July 2003.

   [7]   Yergeau, F., "UTF-8, a transformation format of ISO 10646",
         STD 63, RFC 3629, November 2003.

   [8]   Lemon, T. and S. Cheshire, "Encoding Long Options in the
         Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
         November 2002.

   [9]   Droms, R., "DNS Configuration options for Dynamic Host
         Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
         December 2003.

   [10]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
         January 2004.

   [11]  Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.
         Polk, "Geopriv Requirements", RFC 3693, February 2004.

   [12]  Danley, M., Mulligan, D., Morris, J., and J. Peterson, "Threat
         Analysis of the Geopriv Protocol", RFC 3694, February 2004.

   [13]  Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W., and
         J. Peterson, "Presence Information Data Format (PIDF)",
         RFC 3863, August 2004.

   [14]  Schulzrinne, H. and H. Tschofenig, "Location Types Registry",



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         draft-ietf-geopriv-location-types-registry-03 (work in
         progress), August 2005.

   [15]  International Organization for Standardization, ISO., "ISO
         15924:2004.  Information and documentation - Codes for the
         representation of names of scripts", January 2004.

8.2  Informative References

   [16]  Phillips, A. and M. Davis, "Tags for Identifying Languages",
         draft-ietf-ltru-registry-14 (work in progress), October 2005.

   [17]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
         Considerations Section in RFCs", BCP 26, RFC 2434,
         October 1998.

   [18]  Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
         Configuration Protocol Option for Coordinate-based Location
         Configuration Information", RFC 3825, July 2004.

   [19]  Peterson, J., "A Presence-based GEOPRIV Location Object
         Format", RFC 4119, December 2005.

   [20]  United States Postal Service, "Postal Addressing Standards",
         November 2000.

   [21]  National Emergency Number Assocation, "NENA Recommended Formats
         and Protocols For ALI Data Exchange, ALI Response and GIS
         Mapping", NENA NENA-02-010, January 2002.


Author's Address

   Henning Schulzrinne
   Columbia University
   Department of Computer Science
   450 Computer Science Building
   New York, NY  10027
   US

   Phone: +1 212 939 7004
   Email: hgs+geopriv@cs.columbia.edu
   URI:   http://www.cs.columbia.edu








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Appendix A.  Acknowledgments

   Harald Alvestrand, Stefan Berger, Peter Blatherwick, Joel M. Halpern,
   David Kessens, Cheng-Hong Li, Rohan Mahy, James Polk, Martin Thomson
   and Hannes Tschofenig provided helpful comments.  Examples and
   inspiration were drawn from the Street Address Data Standard of the
   Federal Geographic Data Committee.












































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