Verilink WANsuite 5260 Reference Manual page 39

In addition to the error parameters found in the Error Status and Thresholds
Table on the Network screens, the following error parameters are included on
the Network Performance/Summary table:
BES Sets the Bursty Error Seconds (BES) threshold. A BES is a 1-second period
during which at least more than one but fewer than 320 CRC6 errors
occurred.
LOFC The Loss of Frame Count (LOFC) represents the number of time a loss of
frame is declared. A loss of frame is declared after 2.5 seconds of continuous
loss of signal or OOF.
CRCES Sets the Cyclic Redundancy Check Errored Seconds (CRCES) threshold. A
CRC is a method of confirming the integrity of received data.
Beneath the Performance/Summary table are two buttons: "Performance 24
Hour" and "Performance 30 Day." Clicking either of these buttons will
display a detailed summary of the error events that have occurred during each
15-minute interval of the past 24 hours (Figure 3.6) or during each interval
(day) of the past 30 days (Figure 3.7).
Figure 3.6 Performance 24 Hour Screen
W e b S e r v e r I n t e r f a c e 3-9