Abstract: A technique involves operating an electronic device having data communications ports. Each data communications port includes PHY circuitry to provide Physical Layer network functionality to the electronic device. The technique includes monitoring a particular PCS status signal from the PHY circuitry. The PCS status signal has (i) a PCS_OK value when a first data communications port is operating reliably in data mode and (ii) a PCS_NOT_OK value when the first data communications port is not operating reliably in data mode. The technique further includes detecting a transition event while monitoring the PCS status signal. The transition event involves the PCS status signal initially having the PCS_OK value and transitioning to having the PCS_NOT_OK value. The technique further includes, in response to detection of the transition event, outputting an electronic warning indication to enable failover from the first data communications port to a second data communications port.

Abstract: Power control circuitry (i) applies an inline power signal from a power source to first and second terminals when a control signal delivered to the power control circuitry has an inline-power-ON value and (ii) shuts off the inline power signal from the power source to the first and second terminals when the control signal delivered to the power control circuitry has an inline-power-OFF value. Detection of an inline power shutoff failure includes obtaining a measurement signal from sensing circuitry while the control signal delivered to the power control circuitry has the inline-power-OFF value, and generating a result signal based on the measurement signal. The result signal indicates whether the power control circuitry is applying the inline power signal from the power source to the first and second terminals while the control signal delivered to the power control circuitry has the inline-power-OFF value due to an inline power shutoff failure.