Nortel Networks Corporation

Synoptics Communications, Inc.

Bay Networks, Inc.

Robert W Smith

Kevin G Smith

Keith S Fischer

Corey A Selby

David Stevens

Ilan Raab

Karl Reinke

Sri Reddy

Tom Slykhouse

Julio J Guerra

Kris Kalbarczyk

Dan Simone

A system is provided for communicating data between a first device and a second device across a communication link. Data is communicated between the first device and the second device across the communication link using a first protocol. Management information is communicated between the first device and the second device across the communication link using a second protocol. The system is capable of determining whether the first device is capable of communicating management information with the second device. If the first device is capable of communicating management information with the second device, then the system enables the communication of management information between the first device and the second device.

Method and apparatus for communicating data and management information

A method and apparatus for monitoring the performance of a dedicated communications medium in a switched data networking environment wherein a probe having a bypass circuit allows promiscuous monitoring of all traffic between a switch and a network device, such as a file server, in either direction, and in full duplex mode. Additionally, the bypass circuit eliminates the requirement for a separate repeater between the switch and the network device.

Method and apparatus for monitoring a dedicated communications medium in

A data communications network providing for automatic reconfiguration of a hub concentrator or the like dependent on the protocol used by a device attached to the concentrator. The concentrator includes a circuit for receiving a message packet from a device coupled with the concentrator and for determining the protocol used in the transmission. Utilization of the disclosed circuit provides for automatic reconfiguration in the event a device is moved from one port on the concentrator to another port or a new device is connected to the concentrator.

Protocol independent switch

A token ring local area network concentrator which permits computers and other types of data terminal equipment to communicate with each other. The concentrator has several ports for connecting to the data terminal equipment and to other concentrators, with each port for connecting to the data terminal equipment having associated circuitry for regenerating and retiming data in the ring so as to reduce amplitude and phase distortion such as phase jitter. The associated circuitry includes a passive L/C tank circuit which is excited by the received data and which rings or resonates at a frequency which is preferably an integral multiple of the frequency or bit rate of the received data. The tank circuit functions to remove much of the phase jitter from the received data, thereby permitting a large number of data terminal equipment to be added to the ring and permitting longer lobe cable lengths, with lobe cables functioning to connect the data terminal equipment to the concentrator.

Token ring concentrator having retiming function

An apparatus for monitoring whether a cable is coupled to a port of a computer network. A free-running oscillator is initially set to a base frequency when a cable is not coupled to the port. If a cable is subsequently coupled to that port, the inherent capacitance of that cable loads one of the nodes associated with the oscillator. The result of this capacitance is that the oscillator is now running at a lower frequency. A frequency counter and threshold comparator are used to detect whether the oscillator frequency has fallen below a pre-determined frequency threshold. If the oscillator frequency has not fallen below this threshold, the port is not included in the network path. However, if the oscillator frequency has fallen below the threshold, this indicates that a cable has been coupled to the port. Consequently, the trunk port is inserted into the computer network's path.

Apparatus and method for monitoring the presence of cables connected to

In a terminal coupled to a computer network, a circuit for compensating for the baseline wander of received digital signals. The terminal is AC coupled to the computer network by a coupling transformer. The received digital signal is summed with a correction signal. The resulting summed signal is input to a comparator. This comparator compares the summed signal to a predetermined baseline level. Thus, the output signal from the comparator is fixed at the baseline level. The correction signal is the difference between the summed signal and the output signal from the comparator. The correction signal is filtered and amplified before being fed back to the comparator.

Data transmitter baseline wander correction circuit

In a computer network having a cable for transmission of electrical signals between data terminal equipment and a device used to control and route data in the network, an apparatus for terminating the cable to minimize emissions radiating from the cable and susceptibility of the cable to outside interferences. The cable is comprised of unshielded twisted pairs of wires. Each twisted pair is individually terminated into a matching input impedance. The difference signals being conducted in each twisted pair produces common mode currents which sets up standing waves through the cable. Consequently, at each end of the cable, the common mode of the twisted pairs is terminated into a load having an impedance approximately equal to the common mode impedance of the twisted pairs. These loads effectively dissipate the energy from the standing waves, thereby minimizing emissions. Reciprocally, susceptibility is likewise minimized.

Growing community of inventors

Los Altos, CA, United States of America

Robert W Smith