US Patent 6,947,978

The assignee of US 6,947,978 is The United States of America as represented by the Director, National Security Agency (Washington, DC).

The first claim:

1. A method for geolocating network equipment associated with a logical network address on a communications network, comprising the steps of:

measuring a network latency from a plurality of network stations to a plurality of network endpoints of known physical location by

pinging said network endpoints from said network stations multiple times over a calibration period,

determining round-trip propagation times between each of said network stations and each of said network endpoints over the calibration period from said pinging, and

setting the network latency for each combination of said network stations and said network endpoints to the corresponding minimum round-trip propagation time determined for each of said combination of said network stations and said network endpoints;

measuring the network latency from each of said network stations to said network equipment by

pinging said network equipment from said network stations,

determining the minimum round-trip propagation time between each of said network stations and said network equipment, and

setting the network latency between each of said network stations and said network equipment to the corresponding minimum round-trip propagation time determined;

for each of said network endpoints arranging the network latency from the network endpoint to each of said network stations in turn, in a particular order, as vector elements in an endpoint vector;

arranging the network latency from said network equipment to each of said network stations in turn, in said particular order, as vector elements in a network equipment vector;

determining a distance between the network equipment vector and each of the endpoint vectors; and

identifying the physical location of the network equipment as proximate to said known physical location of the network endpoint corresponding to the endpoint vector having said distance to the network equipment vector not greater than the distance from any other of the endpoint vectors to the target equipment vector.

Geo-location, sometimes called "geo-targeting" when used to deliver advertising, is an increasingly attractive area for Internet businesses. DoubleClick has licensed geo-location technology to deliver location-dependent advertising, and Visa has signed a deal to use the concept to identify possible credit card fraud in online orders.