In a data transmission network, such as a passive optical network, the consecutive identical digit (CID) handling requirements may be reduced by providing a CID monitoring module at the transmitter end that monitors the number of CIDs in a transmission stream. Where the CID number exceeds a threshold, an error generation module induces an error in the transmission stream to reduce the CID below the threshold. The modified transmission stream may then be transmitted to a receiver, allowing clock recovery be performed with improved stability at the receiver. Once clock recovery is achieved, the receiver can then process the transmission stream to correct the errors induced at the transmitter end.