This Unsigned64 is an aggregated fault bitmap rolled up onto this link object from any faults raised against it or its children. It matters on the internal Ethernet link that carries a blade's traffic from the chassis I/O Module up to a Fabric Interconnect over the backplane because it lets monitoring tools detect that something is wrong with the link from one field, without having to separately poll every possible fault code. A nonzero fltAggr on this backplane link is the signal that sends an admin to the UCS Manager fault summary for chassis 4, slot 8, to see exactly which condition (e.g. a transceiver mismatch) was raised.