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rfc:rfc1712

Network Working Group C. Farrell Request for Comments: 1712 M. Schulze Category: Experimental S. Pleitner

                                                            D. Baldoni
                                       Curtin University of Technology
                                                         November 1994
               DNS Encoding of Geographical Location

Status of this Memo

 This memo defines an Experimental Protocol for the Internet
 community.  This memo does not specify an Internet standard of any
 kind.  Discussion and suggestions for improvement are requested.
 Distribution of this memo is unlimited.

Abstract

 This document defines the format of a new Resource Record (RR) for
 the Domain Naming System (DNS), and reserves a corresponding DNS type
 mnemonic and numerical code.  This definition deals with associating
 geographical host location mappings to host names within a domain.
 The data shown in this document is fictitious and does not
 necessarily reflect the real Internet.

1. Introduction

 It has been a long standing problem to relate IP numbers to
 geographical locations. The availability of Geographical location
 information has immediate applications in network management.  Such
 information can be used to supplement the data already provided by
 utilities such as whois [Har85], traceroute [VJ89], and nslookup
 [UCB89].  The usefulness and functionality of these already widely
 used tools would be greatly enhanced by the provision of reliable
 geographical location information.
 The ideal way to manage and maintain a database of information, such
 as geographical location of internet hosts, is to delegate
 responsibility to local domain administrators. A large distributed
 database could be implemented with a simple mechanism for updating
 the local information.  A query mechanism also has to be available
 for checking local entries, as well as inquiring about data from
 non-local domains.

Farrell, Schulze, Pleitner & Baldoni [Page 1] RFC 1712 DNS Encoding of Geographical Location November 1994

2. Background

 The Internet continues to grow at an ever increasing rate with IP
 numbers allocated on a first-come-first-serve basis.  Deciding when
 and how to setup a database of geographical information about
 internet hosts presented a number of options.  The uumap project
 [UU85] was the first serious attempt to collect geographical location
 data from sites and store it centrally.  This project met with
 limited success because of the difficulty in maintaining and updating
 a large central database.  Another problem was the lack of tools for
 the checking the data supplied, this problem resulted in some
 erroneous data entering the database.

2.1 SNMP:

 Using an SNMP get request on the sysLocation MIB (Management
 Information Base) variable was also an option, however this would
 require the host to be running an appropriate agent with public read
 access.  It was also felt that MIB data should reflect local
 management data (e.g., "this" host is on level 5 room 74) rather than
 a hosts geographical position.  This view is supported in the
 examples given in literature in this area [ROSE91].

2.2 X500:

 The X.500 Directory service [X.500.88] defined as part of the ISO
 standards also appears as a potential provider of geographical
 location data. However due to the limited implementations of this
 service it was decided to defer this until this service gains wider
 use and acceptance within the Internet community.

2.3 BIND:

 The DNS [Mock87a][Mock87b] represents an existing system ideally
 suited to the provision of host specific information. The DNS is a
 widely used and well-understood mechanism for providing a distributed
 database of such information and its extensible nature allows it to
 be used to disseminate virtually any information.  The most commonly
 used DNS implementation is the Berkeley Internet Name Domain server
 BIND [UCB89].  The information we wished to make available needed to
 be updated locally but available globally; a perfect match with the
 services provided by the DNS. Current DNS servers provide a variety
 of useful information about hosts in their domain but lack the
 ability to report a host's geographical location.

Farrell, Schulze, Pleitner & Baldoni [Page 2] RFC 1712 DNS Encoding of Geographical Location November 1994

3. RDATA Format

      MSB                                        LSB
      +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
      /                 LONGITUDE                  /
      +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
      /                  LATITUDE                  /
      +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
      /                  ALTITUDE                  /
      +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 where:
 LONGITUDE The real number describing the longitude encoded as a
           printable string. The precision is limited by 256 charcters
           within the range -90..90 degrees. Positive numbers
           indicate locations north of the equator.
 LATITUDE The real number describing the latitude encoded as a
          printable string. The precision is limited by 256 charcters
          within the range -180..180 degrees. Positive numbers
          indicate locations east of the prime meridian.
 ALTITUDE The real number describing the altitude (in meters) from
          mean sea-level encoded as a printable string. The precision
          is limited by 256 charcters. Positive numbers indicate
          locations above mean sea-level.
 Latitude/Longitude/Altitude values are encoded as strings as to avoid
 the precision limitations imposed by encoding as unsigned integers.
 Although this might not be considered optimal, it allows for a very
 high degree of precision with an acceptable average encoded record
 length.

4. The GPOS RR

 The geographical location is defined with the mnemonic GPOS and type
 code 27.
 GPOS has the following format:
         <owner> <ttl> <class> GPOS <longitude> <latitude> <altitude>
 A floating point format was chosen to specify geographical locations
 for reasons of simplicity.  This also guarantees a concise
 unambiguous description of a location by enforcing three compulsory
 numerical values to be specified.

Farrell, Schulze, Pleitner & Baldoni [Page 3] RFC 1712 DNS Encoding of Geographical Location November 1994

 The owner, ttl, and class fields are optional and default to the last
 defined value if omitted. The longitude is a floating point number
 ranging from -90 to 90 with positive values indicating locations
 north of the equator.  For example Perth, Western Australia is
 located at 32^ 7` 19" south of the equator which would be specified
 as -32.68820.  The latitude is a number ranging from -180.0 to 180.0.
 For example Perth, Western Australia is located at 116^ 2' 25" east
 of the prime meridian which would be specified as 116.86520.  Curtin
 University, Perth is also 10 meters above sea-level.
 The valid GPOS record for a host at Curtin University in  Perth
 Western Australia would therefore be:
              GPOS -32.6882 116.8652 10.0
 There is no limit imposed on the number of decimal places, although
 the length of the encoded string is limited to 256 characters for
 each field. It is also suggested that administrators limit their
 entries to the minimum number of necessary characters in each field.

5. Master File Format

 Each host requires its own GPOS field in the corresponding  DNS RR to
 explicitly specify its geographical location and altitude.  If the
 GPOS field is omitted, a DNS enquiry will return no position
 information for that host.
 Consider the following example:

; Authoritative data for cs.curtin.edu.au. ; @ IN SOA marsh.cs.curtin.edu.au. postmaster.cs.curtin.edu.au.

              (
                      94070503        ; Serial (yymmddnn)
                      10800           ; Refresh (3 hours)
                      3600            ; Retry (1 hour)
                      3600000         ; Expire (1000 hours)
                      86400           ; Minimum (24 hours)
              )
              IN      NS      marsh.cs.curtin.edu.au.

marsh IN A 134.7.1.1

              IN      MX      0       marsh
              IN      HINFO   SGI-Indigo IRIX-4.0.5F
              IN      GPOS    -32.6882 116.8652 10.0

ftp IN CNAME marsh

Farrell, Schulze, Pleitner & Baldoni [Page 4] RFC 1712 DNS Encoding of Geographical Location November 1994

lillee IN A 134.7.1.2

              IN      MX      0       marsh
              IN      HINFO   SGI-Indigo IRIX-4.0.5F
              IN      GPOS    -32.6882 116.8652 10.0

hinault IN A 134.7.1.23

              IN      MX      0       marsh
              IN      HINFO   SUN-IPC SunOS-4.1.3
              IN      GPOS    -22.6882 116.8652 250.0

merckx IN A 134.7.1.24

              IN      MX      0       marsh
              IN      HINFO   SUN-IPC SunOS-4.1.1

ambrose IN A 134.7.1.99

              IN      MX      0       marsh
              IN      HINFO   SGI-CHALLENGE_L IRIX-5.2
              IN      GPOS    -32.6882 116.8652 10.0
 The hosts marsh, lillee, and ambrose are all at the same geographical
 location, Perth Western Australia (-32.68820 116.86520). The host
 hinault is at a different geographical location, 10 degrees north of
 Perth in the mountains (-22.6882 116.8652 250.0). For security
 reasons we do not wish to give the location of the host merckx.
 Although the GPOS clause is not a standard entry within BIND
 configuration files, most vendor implementations seem to ignore
 whatever is not understood upon startup of the DNS.  Usually this
 will result in a number of warnings appearing in system log files,
 but in no way alters naming information or impedes the DNS from
 performing its normal duties.

Farrell, Schulze, Pleitner & Baldoni [Page 5] RFC 1712 DNS Encoding of Geographical Location November 1994

7. References

 [ROSE91]        Rose M., "The Simple Book: An Introduction to
                 Management of TCP/IP-based Internets", Prentice-Hall,
                 Englewood Cliffs, New Jersey, 1991.
 [X.500.88]      CCITT: The Directory - Overview of Concepts, Models
                 and Services", Recommendations X.500 - X.521.
 [Har82]         Harrenstein K, Stahl M., and E. Feinler,
                 "NICNAME/WHOIS" RFC 812, SRI NIC, March 1982.
 [Mock87a]       Mockapetris P., "Domain Names - Concepts and
                 Facilities", STD 13, RFC 1034, USC/Information
                 Sciences Institute, November 1987.
 [Mock87b]       Mockapetris P., "Domain Names - Implementation and
                 Specification", STD 13, RFC 1035, USC/Information
                 Sciences Institute, November 1987.
 [FRB93]         Ford P., Rekhter Y., and H-W. Braun, "Improving the
                 Routing and Addressing of IP", IEEE Network
                 Vol.7, No. 3, pp. 11-15, May 1993.
 [VJ89]          Jacobsen V., "The Traceroute(8) Manual Page",
                 Lawrence Berkeley Laboratory, Berkeley,
                 CA, February 1989.
 [UCB89]         University of California, "BIND: Berkeley Internet
                 Name Domain Server", 1989.
 [UU85]          UUCP Mapping Project, Software available via
                 anonymous FTP from ftp.uu.net., 1985.

8. Security Considerations

 Once information has been entered into the DNS, it is considered
 public.

Farrell, Schulze, Pleitner & Baldoni [Page 6] RFC 1712 DNS Encoding of Geographical Location November 1994

9. Authors' Addresses

 Craig Farrell
 Department of Computer Science
 Curtin University of technology
 GPO Box U1987 Perth,
 Western Australia
 EMail: craig@cs.curtin.edu.au
 Mike Schulze
 Department of Computer Science
 Curtin University of technology
 GPO Box U1987 Perth,
 Western Australia
 EMail: mike@cs.curtin.edu.au
 Scott Pleitner
 Department of Computer Science
 Curtin University of technology
 GPO Box U1987 Perth,
 Western Australia
 EMail: pleitner@cs.curtin.edu.au
 Daniel Baldoni
 Department of Computer Science
 Curtin University of technology
 GPO Box U1987 Perth,
 Western Australia
 EMail: flint@cs.curtin.edu.au

Farrell, Schulze, Pleitner & Baldoni [Page 7]

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