Reference Manual

Transport network O&M functions-DXX Support
part of the unavailable time. A new period
of available time begins at the onset of 10
consecutive seconds with no SES detected.
These 10 seconds are considered to be
part of the available time.
SES A severely errored second (SES) is a
second with at least one of the following
events.
For E1 system:
- At least N1 CRC errors (when CRC is
used)
- At least N4 Faulty FSW (when CRC is
not used)
- Loss of frame alignment (LOF)
- Loss of signal (LOS)
- Alarm indication signal (AIS)
and for T1 system:
- At least N1 CRC errors
- Loss of frame alignment (LOF)
- Loss of signal (LOS)
- Alarm indication signal (AIS)
The default values N1 and N4 are stated
in, and the SES is performed in
accordance with [TIH_E1] and [TIH_T1].
ES An error second (ES) is a second with at
least one of the following events:
For E1 system:
- At least 1 CRC errors (when CRC is
used)
- At least 1 Faulty FSW (when CRC is
not used)
- Loss of frame alignment (LOF)
- Loss of signal (LOS)
- At least one slip
- Alarm indication signal (AIS)
- At least N1 CRC errors
- Loss of frame alignment (LOF)
- Loss of signal (LOS)
- At least one slip
EN/LZT 720 0008 R1A
2001-06-26
393 (421)
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