Abstract: A method and system for secured data communication where a plurality of users communicate through ports on a common communication channel. The users communicate by transmitting and receiving data packets. The data packets are transmitted with a variety of fields of information, including but not limited to a destination address, a source address and a source port ID. A security module is connected to the common communication channel and reads the data packet contents and the source port ID. The security module then checks this information to see if the data packet is eligible to be transmitted on the common communication channel and to check which ports are eligible to receive the data packet. If the data packet is not eligible to be transmitted on the common communication channel, the security module destroys the data packet. The security module also sends out a security message on a security channel indicating which ports are eligible to receive the data packet.

Abstract: A backplane communication system based on CSMA/CD protocol including a plurality of communication nodes and method of encoding/decoding data via backplane bus. Each communication node (1) has transmit and receive data links (2,3) connected to the backplane bus (8) via an encoder/decoder (4,5) and also has a transmitter/receiver (6,7) whereby all data transmitted by any node may be passed to the backplane bus and between all communication nodes. Each node is synchronized by the backplane clock (9), so that data may be transmitted and received by the communication nodes via the backplane bus in a synchronous mode. The encoder/decoder provides for detecting a collision on the backplane bus as well as for passing slot identification information between communication nodes.

Abstract: A method and apparatus for providing secure communication on open networks. Each port of the network is provided with a security entity which monitors the communication between one port to the other. End stations connected to the ports communicate with other end stations by transmitting data to the port and receiving data from the port. The data is sent out in data packets with a destination address and a source address. Each port has its own unique address. The security entity checks data packets coming into the port for a destination address. The destination address of incoming data packets is compared with the port address of the affiliated port. Also, outgoing data packets from an end station to a port are also monitored by the security entity. The security entity compares the destination and source address of the data packet with the affiliated port address.

Abstract: A system is provided implementing an extremely high speed link allowing selection of either twisted pair (or like media) and fiber media in a single local area network to provide a high speed multimedia local area network. A high speed transmission link for twisted pair, coaxial cable media or the like is provided including a transmitter with a conversion device for receiving fiber optic data interface signals intended to drive a fiber optic data interface and for converting said fiber optic data interface signals into high speed transmission link signals of a form suitable to drive a shielded twisted pair medium. A receiver is provided including reconversion apparatus for regenerating the signal received from the shielded twisted pair medium back to an adequate signal level. The transmitter conversion device includes a buffer cooperating with an equalizer and a filter for forming the high speed transmission link signal.

Abstract: A system is provided implementing an extremely high speed link allowing selection of either twisted pair (or like media) and fiber media in to provide a high speed multimedia local area network. A high speed transmission link for twisted pair, coaxial cable media or the like includes a transmitter with a conversion device for receiving fiber optic data interface signals intended to drive a fiber optic data interface and for converting these fiber optic data interface signals into high speed transmission link signals of a form suitable to drive a twisted pair medium. A receiver is provided and includes a reconversion device for regenerating the signal received from the twisted pair medium back to an adequate signal level. The transmitter conversion device includes a buffer cooperating with an equalizer and a filter for forming the high speed transmission link signal. The equalizer provides frequency domain compensation for the characteristics of the twisted pair medium.

Abstract: A local net area network, or LAN, configuration is provided with a multiple generic LAN channel architecture which can be logically and dynamically changed. The configuration control can be applied to each module of the network and to each port of a module of a LAN hub. The architecture provides multiple LAN protocols to be used simultaneously, as needed, through protocol specific functions. Industry standard protocol such as: token bus, token ring, and fiber distributed data interface (FDDI), can be implemented using the generic channel architecture and its characteristics providing respective network functions. The architecture also provides a digital collision detection method and provides information necessary for precise network statistics monitoring. The token passing ring architecture provides a logical ring formation within the generic channel. A token passing bus architecture uses modified Ethernet.TM.

Abstract: A collision signal detection system for shared, multi-user, frequency-division-multiplexed transmission media includes a plurality of listening stations connected to the shared, multi-user, frequency-division-multiplexed transmission media. The listening stations receive and transmit signals including data signals within a databand. A collision signal means is associated with each of the plurality of listening stations for sending a collision enforcement signal from one of the plurality of listening stations to the other ones of the plurality of stations after a data collision has been detected at the first station, the collision enforcement signal having a frequency within the data band. A central station is provided with an input connected with the output of each of the listening stations and an output connected with the input of each of the listening stations with all signals passing through the central station.