3com Corporation

Ember Corporation

Patrick Michael Overs

David J Law

Alan R Poulter

Quang T Tran

Christopher Alan Walker

Nicholas Mark Stapleton

Nigel Horspool

Paul Cramphorn

Steven Brewer

Ronald R Aszkenasy

Nicholas James Horne

David R Smith

Johann Ziegler

A clock distribution approach includes distributing a clock signal from a clock tree to a first set of circuit elements characterized by a first circuit characteristic; and distributing a clock signal from a sub-tree of the clock tree to a second set of circuit elements characterized by a second circuit characteristic different from the first circuit characteristic.

Clock skew compensation

The invention concerns the establishment of the rate of transmission of data between two network stations by means of auto-negotiation. The execution of an auto-negotiation sequence by a state machine is counted and if the number of executions of the sequence exceeds a threshold, the auto-negotiation sequence is modified to establish a data rate lower than a previously negotiated rate. A particular example is described for use in accordance with IEEE standard 802.3. In a specific example, monitoring of the execution of the auto-negotiation sequence comprises counting the occurrences of a 'page received' bit in an auto-negotiation expansion register.

Monitoring of connection between network devices in a packet-based communication system

The invention concerns an improvement to an auto-negotiation process for a link between network devices and in particular the avoidance of ambiguity when signals at a higher rate, such as 100BASE-Tx scrambled idle signals, resemble signals at a lower rate, such as 10BASE-T link pulses. Analog and digital filtration is employed to identify 100BASE-Tx energy more accurately and a resultant indicating signal is used in conjunction with another signal characteristic of the higher rate signals, such as a descrambler lock signal, to ensure that the link is not established unless the bit error rate is reasonably low.

Link technology detection in multiple speed physical links

A network communications device is arranged to have a fast throughput of data packets. This is achieved by recognising that, in protocols such as Ethernet, the first symbols in a data packet do not carry any data and therefore do not necessarily require to be properly carried through a communications hub. Rather, a known number of symbols are discarded from the start of a packet on receipt and replaced on re-transmission. This discarding reduces the reception delays particularly in bussed-architecture repeaters where bus arbitration must take place for each received packet.

Network communication device

A communications apparatus comprising a plurality of communication devices each having a plurality of ports and a data bus interconnecting the plurality of units, wherein each device is provided with means enabling the device to detect automatically its position on the data bus.

Communication device with circuitry to promote cascade series connection including identification of device position in the series and sensing the end device in the series

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Caddington, United Kingdom

Patrick Michael Overs