Down indicates that one or both network adapters linked by a physical connection have failed. A device connection failure breaks connectivity between the management station and each network adapter that the connection links, by generating events at both ends:
A Cable Down diagnosis supersedes a Port Down or an Interface Down diagnosis if the port, interface, or both are down.
A TrunkCable Down diagnosis supersedes a Port Down diagnosis if one or both ports are down.
A NetworkConnection Down diagnosis supersedes an Interface Down diagnosis if one or both interfaces are down.
If the network adapters are not physically connected, a network adapter LogicalConnectionDown diagnosis supersedes a device connection Down diagnosis.
The event used to diagnose device connection Down is network adapter DownOrFlapping for one or both of the network adapters. To distinguish device connection Down from device connection Unstable, the value of the IsNetworkAdapterFlapping attribute of the device connection object must also be set to FALSE.