3com Corporation

Alan R Poulter

David J Law

Quang T Tran

Richard N Bayfield

Sharon L Wiles

Paul J Moran

Bryan J Donoghue

Christopher Alan Walker

Edward Turner

David Whitfield

Mark A Bobbitt

Patrick Gibson

Patrick Michael Overs

Steven Brewer

Paul Cramphorn

Neil J MacDonald

A connecting unit for use in a system comprising a 'stack' of network communication units having a cascade connection has three ports having lines for forwarding and receiving data packets and for forwarding and receiving control messages. The connecting unit increments a first signal value defining an identification number received by way of a control message at a first port, provides the received signal value by way of a control message to the third port and provides the incremented signal value by way of a control message to the second port. The connecting unit also receives a second signal value defining an active unit count by way of a control message at the first port and provides the second signal value, incremented or not in dependence on a control message received at the third port, in a control message at the second port. The first signal values (UnitIDs) are used to establish the numbering of the units in the stack and the second signal values are used to compute a count of the 'active' units in the stack.

Cascade architecture and operation for packet-based communication systems

A control device for a unit in a cascade connection of network units includes control logic which increments a count of active units and passes the count to the next control device. The count is initiated and terminated by an absence of control messages at the down port and up port respectively. The incremented count is passed up the cascade and a final count is passed down the cascade.

Cascade control architecture and operation for packet-based communication systems

A network device is arranged to transmit a specific identification such as the device's MAC address in Next Pages of auto-negotiation and to determine a link status to be 'down' if 'Next Pages' containing that address are received by the same port. The invention avoids the use of signal detect pins for fiber optic links.

Network device including detection of link status employing auto-negotiation

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

Housing of an electronic extender

Printed circuit board

An extender for use in with a cascade stack of network devices comprises an electronic circuit which has three ports, and circuit connections coupling each of the three ports to each of the other two ports; port connectors for each port; a two-part housing of which a first part has an end wall apertured for the protrusion of a first and a second of the connectors and a second part has an end wall apertured for the protrusion of a third of the port connectors; and screw fixings for securing the housing parts together.

Network extender

A printed circuit board which has in a first edge a first notch and a second notch a first predetermined distance apart and along said first edge between said first and second notches a plurality of terminal pads in a broadside array, the first edge including a third notch spaced from the second notch and disposed a second predetermined distance, greater than the first predetermined distance, from said first notch, the board having along and adjacent the first edge between the second and third notches a second plurality of terminal pads arranged in a respective broadside array.

Printed circuit board having dual purpose profile

Growing community of inventors

Bedford, United Kingdom

Alan R Poulter