This defines what action the fabric takes on this virtual circuit's server-facing side if its associated uplink fails - for example bringing the server-facing vNIC link down too, to force a failover at the OS/NIC-teaming level. An admin relying on OS-level NIC teaming, rather than fabric-level redundancy alone, for failover needs this set correctly, since a link-down action here is what actually notifies the guest OS to fail over to its other NIC when the fabric loses its uplink. A value of 'link-down' here means that if the uplink this circuit depends on fails, the server's vNIC link will also be forced down, prompting NIC-teaming software in the OS to switch to its standby path.