Uplink Failure Detection

Uplink Failure Detection (UFD) is a network path redundancy feature that works in conjunction with NIC teaming functionality. UFD continuously monitors the link state of the ports configured as links-to-monitor (LtM), and when these ports lose link with their partners, UFD will disable the set of ports configured as links-to-disable (LtD.) When an uplink port goes down, UFD enables the switch to auto-disable the specific downlinks connected to the NICs. This allows the NIC teaming software to detect link failure on the primary NIC port and fail over to the secondary NIC in the team.

NIC teams must be configured for switch redundancy when used with UFD, that is, the team spans ports on both Switch A and Switch B. The switch automatically enables the downlink ports when the uplink returns to service. For an example of teamed NICs in conjunction with UFD, see Teamed NICs in conjunction with UFD.) For an example of teamed NICs with a failed uplink, see Teamed NICs with a failed uplink.

For UFD functionality to work as expected, the NIC teaming must be in Network Fault Tolerance (NFT) mode.

Teamed NICs in conjunction with UFD
Teamed NICs with a failed uplink

The state of the LtD is purely governed by the state of the LtM, and is independent of the physical state of the ports in the LtD.