Control method where setup of a link is switched to a lower rate if the number of attempts made to set up the link at a higher rate exceeds a threshold

摘要

The invention covers the auto setup of a data link between two components which may be on a network and may use packet transmissions. The components follow a conventional auto negotiation procedure in which they request data on each others allowable transmission rates 32, monitor the number of errors occurring in the link 41,42 and where the number of errors exceeds a threshold the system may cause the link to switch to a lower transmission rate 40. The invention additionally monitors the number of times that negotiation of the setup of the transmission link has been attempted 38, and if a threshold is exceeded the transmission rate will be set to a lower speed. In the example the system operates in accordance with IEEE standard 802.3, and the system counts the occurrences of a 'page received' in an auto negotiation expansion register to monitor the number of times execution of the link setup has been attempted. The setup procedure may be realised as a state machine.