rfc2009.txt
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Network Working Group T. ImielinskiRequest for Comments: 2009 J. NavasCategory: Experimental Rutgers University November 1996 GPS-Based Addressing and RoutingStatus 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.IANA Note: This document describes a possible experiment with geographic addresses. It uses several specific IP addresses and domain names in the discussion as concrete examples to aid in understanding the concepts. Please note that these addresses and names are not registered, assigned, allocated, or delegated to the use suggested here.Table of Contents 1. Introduction...................................... 2 1b. General Architecture...................... 3 1c. Scenarios of Usage: Interface Issues...... 3 2. Addressing Model.................................. 4 2a. Using GPS for Destination Addresses....... 5 3. Routing........................................... 7 3a. GPS Multicast Routing Scheme (GPSM)...... 7 3a-i. Multicast Trees................... 8 3a-ii. Determining the GPS Multicast Addressing........................ 10 3a-iii. Building Multicast Trees.......... 11 3a-iv. Routing........................... 12 3a-v. DNS Issues........................ 12 3a-vi. Estimations....................... 12 3b. "Last Mile" Routing..................... 13 3b-i. Application Level Filtering....... 13 3b-ii. Multicast Filtering............... 13 3b-iii. Computers on Fixed Networks....... 14 3c. Geometric Routing Scheme (GEO)........... 14 3c-i. Routing Overview.................. 14 3c-ii. Supporting Long-Duration GPScasts. 16 3c-iii. Discovering A Router's Service Area 17Imielinski & Navas Experimental [Page 1] RFC 2009 GPS-Based Addressing and Routing November 1996 3c-iv. Hierarchical Router Structure and Multicast Groups.................. 18 3c-v. Routing Optimizations............. 19 3c-vi. Router-Failure Recovery Scheme.... 19 3c-vii. Domain Name Service Issues........ 20 4. Router Daemon and Host Library.................... 21 4a. GPS Address Library - SendToGPS()......... 21 4b. Establishing A Default GPS Router......... 22 4c. GPSRouteD................................. 22 4c-i. Configuration...................... 23 4d. Multicast Address Resolution Protocol (MARP) 23 4e. Internet GPS Management Protocol (IGPSMP). 24 5. Working Without GPS Information................... 25 5a. Users Without GPS Modules................. 25 5b. Buildings block GPS radio frequencies What then?................................ 25 6. Application Layer Solution........................ 25 7. Reliability....................................... 26 8. Security Considerations........................... 27 9. References........................................ 27 10. Authors' Addresses................................ 271. Introduction In the near future GPS will be widely used allowing a broad variety of location dependent services such as direction giving, navigation, etc. In this document we propose a family of protocols and addressing methods to integrate GPS into the Internet Protocol to enable the creation of location dependent services such as: o Multicasting selectively only to specific geographical regions defined by latitude and longitude. For example, sending an emergency message to everyone who is currently in a specific area, such as a building or train station. o Providing a given service only to clients who are within a certain geographic range from the server (which may be mobile itself), say within 2 miles. o Advertising a given service in a range restricted way, say, within 2 miles from the server,Imielinski & Navas Experimental [Page 2] RFC 2009 GPS-Based Addressing and Routing November 1996 o Providing contiguous information services for mobile users when information depends on the user's location. In particular providing location dependent book-marks, which provides the user with any important information which happens to be local (within a certain range) possibly including other mobile servers. The solutions which we present are flexible (scalable) in terms of the target accuracy of the GPS. We also discuss cases when GPS cannot be used (like inside buildings). The main challenge is to integrate the concept of physical location into the current design of the Internet which relies on logical addressing. We see the following general families of solutions: a) Unicast IP routing extended to deal with GPS addresses b) GPS-Multicast solution c) Application Layer Solution using extended DNS The first two solutions are presented in this memo. We only sketch the third solution.1b. General Architecture We will assume a general cellular architecture with base stations called Mobile Support Stations (MSS). We will consider a wide variety of cells, including outdoor and indoor cells. We will discuss both cases when the mobile client has a GPS card on his machine and cases when the GPS card does not work (i.e. - inside buildings). We will assume that each MSS covers a cell with a well defined range specified as a polygon of spatial coordinates and that the MSS is aware of its own range.1c. Scenarios of Usage and Interface Issues Below, we list some possible scenarios of usage for the geographic messaging. Consider an example situation, of an area of land near a river. During a severe rain storm, the local authorities may wish to send a flood warning to all people living within a hundred meters of the river.Imielinski & Navas Experimental [Page 3] RFC 2009 GPS-Based Addressing and Routing November 1996 For the interface to such messaging system we propose to use a zoom- able map similar to the U.S. Census Bureau's Tiger Map Service. This map would allow a user to view a geographical area at varying degrees of magnitude. He could then use a pointing device, such as a mouse, to draw a bounding polygon around the area which will receive the message to be sent. The computer would then translate the drawn polygon into GPS coordinates and use those coordinates when sending and routing the message. Geographical regions specified using this zoom-able map could be stored and recalled at a later time. This zoom-able map is analogous to the IP address books found in many email programs. To continue with the above example, local officials would call up a map containing the river in danger of overflowing. They would then hand-draw a bounding polygon around all of the areas at least a hundred yards from the river. They would specify this to be the destination for a flood warning email to all residents in the area. The warning email would then be sent. Similar applications include traffic management (for example, reaching vehicles which are stuck in traffic) and security enforcement. Other applications involve general client server applications where servers are selected on the basis of the geographic distance. For example, one may be interested in finding out all car dealers within 2 miles from his/her location. This leads to an extension of the Web concept in which location and distance play important roles in selecting information. We are currently in the process of implementing location dependent book-marks (hot lists) in which pages associated with static and mobile servers which are present within a certain distance from the client are displayed on the client's terminal.2. Addressing Model Two-dimensional GPS positioning offers latitude and longitude information as a four dimensional vector: <Direction, hours, minutes, seconds> where Direction is one of the four basic values: N, S, W, E; hours ranges from 0 to 180 (for latitude) and 0 to 90 for longitude, and, finally, minutes and seconds range from 0 to 60. Thus <W, 122, 56, 89> is an example of longitude and <N, 85, 66, 43> is an example of latitude.Imielinski & Navas Experimental [Page 4] RFC 2009 GPS-Based Addressing and Routing November 1996 Four bytes of addressing space (one byte for each of the four dimensions) are necessary to store latitude and four bytes are also sufficient to store longitude. Thus eight bytes total are necessary to address the whole surface of earth with precision down to 0.1 mile! Notice that if we desired precision down to 0.001 mile (1.8 meters) then we would need just five bytes for each component, or ten bytes together for the full address (as military versions provide). The future version of IP (IP v6) will certainly have a sufficient number of bits in its addressing space to provide an address for even smaller GPS addressable units. In this proposal, however, we assume the current version of IP (IP v4) and we make sure that we manage the addressing space more economically than that. We will call the smallest GPS addressable unit a GPS-square.2a. Using GPS for Destination Addresses A destination GPS address would be represented by one of the following: o Some closed polygon such as: circle( center point, radius ) polygon( point1, point2, point3, ... , pointn) where each point would be expressed using GPS-square addresses. This notation would send a message to anyone within the specified geographical area defined by the closed polygon. o site-name as a geographic access path This notation would simulate the postal mail service. In this manner, a message can be sent to a specific site by specifying its location in terms of real-world names such as the name of a specific site, city, township, county, state, etc. This format would make use of the directory service detailed later.Imielinski & Navas Experimental [Page 5] RFC 2009 GPS-Based Addressing and Routing November 1996 For example, if we were to send a message to city hall in Fresno, California, we could send it by specifying either a bounding polygon or the mail address. If we specify a bounding polygon, then we could specify the GPS limits of the city hall as a series of connected lines that form a closed polygon surrounding it. Since we have a list of connected lines, we just have to record the endpoints of the lines. Therefore the address of the city hall in Fresno could look like: polygon([N 45 58 23, W 34 56 12], [N 23 45 56, W 12 23 34], ... ) Alternatively, since city hall in Fresno is a well-defined⌨️ 快捷键说明
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