Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
2001-06-19
2003-12-16
Marc-Coleman, Marthe Y. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C455S457000, C455S456500
Reexamination Certificate
active
06665611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to computer networks, and more specifically, to a system for discovering and storing location information for network entities or devices.
2. Background Information
Computer networks typically comprise a plurality of interconnected network entities. A network entity may consist of any device, such as a computer or end station, that “sources” (i.e., transmits) or “sinks” (i.e., receives) datagrams (e.g., packets and/or frames). A common type of computer network is a local area network (“LAN”) which typically refers to a privately owned network within a single building or campus. LANs typically employ a data communication protocol (LAN standard), such as Ethernet, FDDI or token ring, that defines the functions performed by the data link and physical layers of a communications architecture (i.e., a protocol stack). In many instances, several LANs may be interconnected by point-to-point links, microwave transceivers, satellite hookups, etc. to form a wide area network (“WAN”) or intranet that may span an entire country or continent.
One or more intermediate network devices are often used to couple LANs together and allow the corresponding network entities to exchange information. For example, a bridge may be used to provide an interconnecting function between two or more LANs. Alternatively, a switch may be utilized to provide a “switching” function for transferring information between a plurality of LANs or end stations. Bridges and switches may operate at various levels or layers of a communication protocol stack. For example, a switch may operate at layer
2
which, in the Open Systems Interconnection (OSI) Reference Model, is called the data link layer and includes the Logical Link Control (LLC) and Media Access Control (MAC) sub-layers. Frames at the data link layer typically include a header containing the MAC address of the entity sourcing the message, referred to as the source address, and the MAC address of the entity to whom the message is being sent, referred to as the destination address. To perform the switching function, layer
2
switches examine the MAC destination address of each data frame received on a source port. The frame is then switched onto and driven from the destination port(s) associated with that MAC destination address.
Other network devices, commonly referred to as routers, may operate at higher communication layers, such as layer
3
of the OSI Reference Model, which in TCP/IP networks corresponds to the Internet Protocol (IP) layer. Data frames at the IP layer also include a header which contains an IP source address and an IP destination address. is Routers or layer
3
switches may re-assemble or convert received data frames from one LAN standard (e.g., Ethernet) to another (e.g. token ring). Thus, layer
3
devices are often used to interconnect dissimilar subnetworks. Many equipment manufacturers include both layer
2
switching and layer
3
routing functions in a single device.
Often, it is desirable to obtain information about where specific network entities, such as end stations, servers, switches, etc., or specific devices are physically located. For example, network administrators may wish to perform inventories on the equipment making up their computer networks. This information can then be used in determining maintenance schedules, among other applications. Currently, only manual systems exist for collecting and storing such information. Specifically, the network administrator would visit each location, write down identifying information for the network equipment at that location and then enter this information in some type of data base, such as a spreadsheet. Because the creations of such manual inventories are so time consuming, they are rarely performed. They are also error-prone, resulting in the data base having incorrect information. As a result, few network administrators have access to such information even though it could facilitate many applications.
Enhanced 911 Emergency Calling Services
Many communities provide enhanced 911 (E911) emergency telephone calling services. With E911, emergency operators receive the location of 911 calls as well as the telephone number from which the call originated. Location information is obtained from an Automation Location Information (ALI) database. Telephone subscriber information, e.g., name, address, telephone number, is typically used to build the ALI database. For organizations using a private branch exchange (PBX) telephone switch, however, subscriber information is often limited to the organization's name and its main address. As a result, the “address” displayed to emergency operators who receive a 911 call from inside a PBX can be imprecise or even far away from the caller's actual location. In this case, the operator must obtain location information from the caller defeating a major purpose of E911 services.
It is an object of the present invention to provide a system for discovering location information for network entities and devices that is neither time-consuming nor error prone.
It is a further object of the present invention to utilize location information in requests for emergency services.
SUMMARY OF THE INVENTION
Briefly, the present invention is directed to a system for discovering and maintaining geographic location information for computer networks. In accordance with a preferred embodiment, the system includes a computing unit, such as a laptop, notebook or palm personal computer (PC), and a geographic location generator, such as a Global Positioning System (GPS) receiver. The computing unit includes a location discovery entity and a message generator. The GPS receiver, which is mounted to and in communication with the computing unit, may be augmented with an inertial navigation unit to facilitate the generation of location information inside of buildings where GPS signals can be difficult to receive. The computing unit further includes a network interface card (NIC) so that it can communicate with one or more network devices, such as a network switch. The switch includes a location recording/reporting entity and a location database. The recording/reporting entity is configured to receive and recognize messages from the computing unit, and to store information at the location database.
In operation, a user, such as a network administrator, takes the computing unit to a network site for which geographic location information is desired. The GPS receiver is activated to obtain physical coordinates of the site. If the GPS receiver is unable to obtain the coordinates, e.g., due to a weak satellite signal, the user may take the system to a substitute spot where such coordinates can be obtained, e.g., a window. The user then initializes or zeros the inertial navigation unit and returns to the site of interest. The coordinates from the substitute spot are then adjusted by the signals produced by the inertial navigation system so as to produce physical coordinates for the network site of interest.
The physical coordinates are then loaded into a network message and sent to the switch by the computing unit. Specifically, the computing unit's NIC may be connected to a network outlet that is disposed at the site of interest and coupled to the network device. The network device receives the message across the network, and notes the device port on which it was received. The network device then recovers the physical coordinates from the message and stores this information along with a port identifier (ID) in its location database. The geographic location of the network site can thus be bound to a port ID of the network device.
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