The beacon probing option allows the detection of failures unseen by the link status option by sending the Ethernet broadcast frames through all the network cards. These network frames authorize the vSwitch to detect faulty configurations or upstream switch failures and force the failover if the ports are blocked. When using an inverted U physical network topology in conjunction with a dual NIC server, it is recommended that you enable link-state tracking or a similar network feature in order to avoid traffic black holes.

According to VMware's best practices, it is recommended that you have at least three cards before activating this functionality. However, if IP hash is going to be used, beacon probing should not be used as a form of network failure detection in order to avoid an ambiguous state due to the limitation that a packet cannot hairpin on the port it is received. Beacon probing works by sending out and listening to beacon probes from the NICs in a team. If there are two NICs, then each NIC will send out a probe and the other NICs will receive that probe. Because EtherChannel is considered one link, this will not function properly as the NIC uplinks are not logically separate uplinks. If beacon probing is used, this can result in MAC address flapping errors, and the network connectivity may be interrupted.