A method of retraining the clock for receiver

A method of retraining a receiver (24), which comprises: Determining a minimum transition density for a data link derived clock (26) to the receiver; Generating a retraining flit (30, 30 ') the minimum transition density on the base; Defining control data and payload data for the retraining flit (30 '); Determining error detection data for the retraining flit (30 ') based on the control data and the payload data, the control data, the payload data and the error detection data have sufficient transitions to meet the minimum transition density, and Transmitting the retraining flit (30, 30 ') as part of a data signal via the data transmission path to the receiver.