beacon probing
Beacon probing is a networking troubleshooting feature in VMware vSphere that pinpoints failures with physical Ethernet adapters and physical switches.
The beacon probing function in vSphere detects whether network interface cards in a team can receive and broadcast beacon probes from the host to determine their status. This function can also determine if a physical switch has had a power failure, if a cable has been pulled from a physical switch or if there are failures in downstream switches.