The number of DCE polling intervals over which
accumulated errors are counted against the threshold
specified in usdFrDlcmiDceErrorThreshold.
If, within this number of events, the number of errors
equals or exceeds the threshold, the interface is
declared down.
The 'DCE polling interval' is specified by
usdFrDlcmiDcePollingInterval.
Pertains to DCE/NNI operation only. This parameter can
be reconfigured only when the Frame Relay interface
is acting as a DCE or NNI.