There are two methods available in the both vSphere virtual Switches (vSS & vDS) to determine the network failover detection of the ESX host when the physical Network is offline.
Network Failure detection
Using this will detect the link state of the physical adapter. If the physical switch fails or someone unplugs the cable from the NIC or the physical switch, failure will be detected and failover initiated.
- Link Status: only dectect link status not detect any misconfigurations such as VLAN pruning or spanning tree
- Bacon probing: This setting requirement are limited to minimum 3 physical NICs.it will listen for beacon probes on all physical NICs that are part of the team. It will then use the information from the beacon probe to determine the link status. This method will typically be able to detect physical switch misconfigurations as initiate a failover.
There are some other method available that are related to failover settings.
If this is set to “Yes” which is default setting. Then switch can be notified in case of any failure or Virtual NIC is connected to Virtual Switch
It tell us how a physical adapter is returned to active state after recovering from a failure
How Failover Order Works?
There are three network adapter failover options available in the vSphere Virtual Switches.
Active Adapters: All the NIC used in the Active adapter list is used for both inbound & outbound traffic.
Standby adapter: The NICs are in standby mode is only in case of active adapter goes down.
Unused adapter: The listed adapter in this category are not in use