Multiplex communications – Duplex – Duplex repeaters or extenders
Reexamination Certificate
1997-01-06
2001-01-16
Olms, Douglas W. (Department: 2732)
Multiplex communications
Duplex
Duplex repeaters or extenders
C370S453000, C370S457000, C370S463000, C370S501000, C375S211000, C375S257000, C340S538000, C379S348000, C379S413000
Reexamination Certificate
active
06175556
ABSTRACT:
BACKGROUND OF THE INVENTION
The fundamental job of a local area network (“LAN”) is to physically link several personal computers (“PCs”) or workstations to each other, and often to a mainframe or a minicomputer. This is accomplished with a variety of materials--twisted-wire cables, fiber optics, phone lines, and, even, infrared light and radio signals.
One common network configuration is Ethernet, which is a LAN developed by Xerox in 1976, originally for linking minicomputers at the Palo Alto Research Center. Ethernet is a widely implemented network from which the IEEE 802.3 standard for contention networks was developed. Ethernet utilizes a bus topology (configuration) and relies on the form of access known as CSMA/CD (an acronym for Carrier Sense Multiple Access with Collision Detection, which is a network protocol for handling situations in which two or more nodes (stations) transmit at the same time, thus causing a collision) to regulate traffic on the main communication line (bus). Network nodes, or workstations, are typically connected by coaxial cable (in either of two varieties, known as thick and thin) or by twisted-pair wiring. Thin Ethernet cabling is 5 millimeters (about 0.2 inch) in diameter and can connect network stations over a distance of 185 meters (about 600 feet); thick Ethernet cabling is one centimeter (about 0.4 inch) in diameter and can connect stations up to 500 meters (about 1640 feet) apart.
However, with the proliferation of networks within today's business and technology communities and organizations, the above limitations on distances between workstations within a network, such as Ethernet, has become a hinderance to their growth and implementation. The solution has been the implementation of network repeaters, which essentially “amplify” or regenerate the signals transmitted on the communication bus so that nodes or workstations can be located greater distances from each other. Naturally, these repeaters require some sort of power source in order to accomplish their function.
Presently, such repeaters are implemented as either stand-alone repeaters or repeater adapters. A stand-alone repeater, or hub as it is sometimes referred to, has its own power supply and can be located anywhere there is a power outlet. However, such a stand-alone repeater may be located within a wiring closet or some other remotely accessible location within a building, or between buildings, where a power source is not readily available. The result is that power has to be wired to the location of the repeater, which can be burdensome and expensive. An adapter repeater is typically installed within a PC or workstation, thus eliminating the need for a separate power supply. A limitation of the adapter repeater is that the PC or workstation may become congested due to multiple connections to other workstations.
Thus, there is a need in the art for a stand-alone network repeater, which may be provided power from a remote location. There is a further need in the art for an Ethernet repeater that may be remotely powered.
SUMMARY OF THE INVENTION
Thus, it is an object of the present invention to provide a remote powered repeater for a LAN, such as within an Ethernet LAN.
In the attainment of the above object, the present invention, in a preferred embodiment, utilizes power transmitted from a remote source, such as a remotely coupled workstation or PC. By using this remotely supplied power, the present invention creates a stand-alone repeater without a power supply. This reduces the cost and complexity of the repeater and gives the repeater flexibility since it can be located away from a PC or workstation, and no power outlet is required.
Essentially, an attachment unit interface (“AUI”) is utilized to couple a remote workstation to the repeater. The interface is configured so that voltage from the workstation is provided to the repeater. In addition to providing power, the AUI also couples the remote workstation to the network bus.
Within the repeater, the supplied voltage is delivered to a DC to DC converter, which then supplies the various components within the repeater with appropriate converted voltage levels. A noise filter may also be implemented along with the DC to DC converter to suppress any noise entering the repeater through the AUI.
In order for the workstation to be coupled to the network, the AUI from the workstation must interface with the repeater controller. This interfacing may be accomplished by coupling the AUI to the AUI port or the inter-repeater bus of the repeater controller through discreet logic circuitry.
In a further alternative embodiment of the present invention, the repeater may be implemented as a managed repeater by adding a Network Interface Controller (“NIC”), which may be an application specific integrated circuit (“ASIC”).
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.
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ISO/IEC 8802-3: 1993(E) ANSI/IEEE Std. 802.3, 1993 Edition, pp. 87-89, 108-110, 115-121, 165-172, 245-256.
Allen, Jr. James Johnson
Cooper Ronald Julius
Cockburn Joscelyn G.
Hom Shick
International Business Machines - Corporation
Olms Douglas W.
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