A network switch includes first and second clock-and-data-recovery (CDR) circuits, a cross-bar switch electrically coupling the first and second CDR circuits, and a test pattern generation circuit electrically coupled to the first CDR circuit. The test pattern generation circuit is configured to generate a test pattern and transmit the test pattern from the first CDR circuit to the second CDR circuit via the cross-bar switch. The network switch also includes a test pattern checking circuit electrically coupled to the second CDR circuit and configured to verify the test pattern received at the second CDR circuit.