Hello Victor,
Hitesh is right a sort of heartbeat is used but this can use of a L2 communication or a link local 224.0.0.X multicast (some SUN teaming does so for example, HP teaming uses L2 address )destination depending on the implementation in this way the server should be able to understand which NIC is still connected to the network and to detect indirect failure
in the case of HP teaming:
>>Network Fault Tolerance (NFT) is the foundation of HP ProLiant Network Adapter Teaming. In NFT mode, two to
eight ports are teamed together to operate as a single virtual network port. However, only one network port, the
Primary port, is used for both transmit and receive communication with the server. The remaining ports are
considered to be in stand-by (or secondary ports) and referred to as Non-Primary ports, and remain idle unless
the Primary port fails. All ports may transmit and receive heartbeats, including Non-Primary ports.
Also the switches CAM tables are updated using these messages
>>>Update Switch MAC table with team MAC address
The Primary Port must ensure that the switch has the team’s MAC address on the correct port, and that
the switch keeps the team’s MAC address in its MAC table [or Content Addressable Memory (CAM)
table]. The Switch MAC table update heartbeat is used with most team types when a failover occurs,
and a Non-Primary port takes over the Primary role.
Destination MAC address 03-00-C7-00-00-EE this is a multicast MAC address but outside the range used for IPv4 multicast
Hope to help
Giuseppe
