This read-write value sets the number of status-polling intervals over which the N392 error threshold is counted, so that if N392 errors occur within N393 events, the interface is marked down. Together the two values set the sensitivity of down-detection: three errors out of the last four polls is far more trigger-happy than three errors out of the last ten, even with the same N392 value. N392 of 3 with N393 of 4 marks the interface down if 3 out of the last 4 status polls failed, whereas N392 of 3 with N393 of 10 tolerates the same 3 failures spread across ten polls without declaring the link down.