International Business Machines Corporation

Jerry Dagher

Kenneth J Christensen

Thomas E Stammely

Rudolf Eugene Rehquate

Beymer Bevill, Jr

Francis Edward Noel, Jr

James W Sylivant

John Lock Creigh

Frances E Noel

A multi-port LAN switch is provided that enables attached network devices to both communicate directly and to insert into a token-ring network through an attached concentrator. Each port of the multi-port LAN switch has a first transformer, a second transformer, and a switching system. The first transformer has a first winding connected to a first connection of the port. The second transformer has a first winding connected to a second connection of the port. The switching system switches to a port mode or an adapter mode as a function of a mode signal transmitted to the port In the adapter mode, the switching system connects a second winding of the first transformer to a transmitter circuit in the port, and its connects a second winding of the second transformer to a receiver circuit in the port. In the port mode, the switching system connects the second winding of the first transformer to the receiver circuit in the port, and it connects the second winding of the second transformer to the transmitter circuit in the port. Each port of the multi-port LAN switch further includes a DC voltage source that is switchably connected to the first connection of the port through a first switch. Each port further includes a second switch that connects the second connection of the port to a DC return-path in a first position, and connects the second connection to the first connection when in a second position.

Multi-port LAN switch for a token-ring network

A multi-port LAN switch is provided that enables attached network devices to both communicate directly and to insert into a token-ring network through an attached concentrator. Each port of the multi-port LAN switch has a first transformer, a second transformer, and a switching system. The first transformer has a first winding connected to a first connection of the port. The second transformer has a first winding connected to a second connection of the port. The switching system switches to a port mode or an adapter mode as a function of a mode signal transmitted to the port. In the adapter mode, the switching system connects a second winding of the first transformer to a transmitter circuit in the port, and its connects a second winding of the second transformer to a receiver circuit in the port. In the port mode, the switching system connects the second winding of the first transformer to the receiver circuit in the port, and it connects the second winding of the second transformer to the transmitter circuit in the port. Each port of the multi-port LAN switch further includes a DC voltage source that is switchably connected to the first connection of the port through a first switch. Each port further includes a second switch that connects the second connection of the port to a DC return-path in a first position, and connects the second connection to the first connection when in a second position.

A system and method for decreasing the amount of bandwidth required to transmit a high bandwidth signal over electrically conducting transmission lines, wherein the transmission lines are arranged in a symmetrical configuration so that their propagation characteristics permit frequency independent modes of propagation of a plurality of signals to be transmitted thereon. This permits decomposing a high bandwidth signal into lower bandwidth signals, and then encoding these lower bandwidth signals in association with the frequency independent modes of propagation, driving the individual electrically conducting transmission lines with these encoded signals, and then decoding and recombining the signals at the receiving end to recapture the high bandwidth signal.

System and method for transporting high-bandwidth signals over

An equalizer circuit suitable for selectively equalizing a transmission media operating at one of a number of different data rates has a number of equalizers, one for each data rate, connected in parallel to the media and a selectively operable means for disabling all but one of the equalizers.

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Raleigh, NC, United States of America

Jerry Dagher