An Ethernet network switch is disclosed. The network switch includes multiple Ethernet ports, each port including Ethernet transceiver circuitry forming one end of an Ethernet link. The switch also includes control logic to, when the switch is connected to multiple Ethernet cables defining Ethernet links, 1) initiate a diagnostic mode of operation, 2) control at least two of the multiple Ethernet links to measure a parameter associated with alien crosstalk, and 3) configure operation parameters for the links based on the measured parameter.