3Com Corporation

3Com Technologies

Paul Cramphorn

David J Law

Paul J Moran

Alan R Poulter

Patrick Michael Overs

Nigel Horspool

Steven Brewer

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

A data connection between two network stations such as an Ethernet hub and an end station which are both capable of exchanging data at the higher of two rates, the higher rate being selected by an auto-negotiation process, is monitored for the occurrence of error represented by a symbol representing the start of a data packet immediately followed by an idle symbol. The rate of occurrence of such errors is compared against a threshold and the speed of the data connection is downgraded to the lower rate.

Monitoring of connection between an ethernet hub and an end station

Growing community of inventors

Kings Langley, United Kingdom

Paul Cramphorn