Patent ID: 6600755
Filing Date: 2003-07-29
Classification: H04L

Abstract:
Apparatus for the auto-negotiation of operational modes of a physical layer device for use in a packet-based data communication system, including an auto-negotiation state machine which is coupled to a port and is operative to select a mode of operation, said mode including a selection from at least two data rates; wherein the apparatus includes between said port and said state machine:(i) a first signal path arranged to produce a first indicating signal which denotes signals characteristic of the higher of the two data rates; and (ii) a second signal path including a transition counter coupled to said second signal path to count signal transitions of signals of the higher of the two data rates occurring in said second signal path, and disposed to provide a second indicating signal when the counter counts a predetermined number of transitions within a given time; and wherein said state machine requires the presence of both the indicating signals before allowing operation at the higher of the two data rates.