I receive a network redundancy lost error on a ESXi 5.5 host even though there is no sign of a connection error. The cable is connected and the switch port shows it is online. There is a vSwitch configured to connect to a SAN. There are 2 NIC's configured and both of them show up as online in the vCenter. If I disconnect one of the NIC's from that vSwitch I get a "network connectivity lost" error.