Abstract: In optical communications systems crosstalk can result in what is termed silent failure. In silent failure, a faulty transmitter appears to function correctly because a receiver in communication therewith is receiving a signal induced by crosstalk. The invention overcomes this problem by tapping the received signal and monitoring it external to the receiver in order to ensure adequate signal levels for a received signal. A microcontroller disables the failed circuit and in an embodiment switches the communication functions to a stand-by circuit.