Transmission Interface Handling DS1 1544 kbit/s
Two counters for severely errored seconds exist. Both are derived from
the downstream PCM port, but one is closely connected to downstream
faults while the other one is related to upstream faults.
The downstream counter is increased by 1 for each second with at least
one of the events:
•
N1 CRC-6 errors or
•
1 LOF or
•
1 LOS or
•
1 AIS
The upstream counter is increased by 1 for each second with at least one
•
RAI
SES are not counted during unavailable state.
Both SES contours are reported after each BI.
UAS and Unavailable State supervision
UAS is a count of one-second intervals during which service is
unavailable. This period of time is referred to as the unavailable state.
The two directions (upstream and downstream) are supervised
separately. That is, one of the directions can be in the unavailable state
but the other is in the available state.
The counting of ES and SES is stopped for both directions as soon as at
least one of the directions is in the unavailable state.
An unavailable state for one direction is declared at the onset of P
consecutive SES for the direction of interest. These P seconds are
considered to be part of the unavailable time. A new period of available
state begins at the onset of Q consecutive seconds with no SES detected.
These Q seconds are considered to be part of the available time.
The number of unavailable seconds for each direction is reported after
each BI.
33.3.6
Administration
Supervision of transmission faults and transmission quality can be
performed in different ways. With the help of parameters, the
supervision can be configured to meet a wide range of requirements.
The configuration parameters can only be changed when the AO DP is
in state “Disable”. The parameters of interest are given below.
•
The parameters P and Q
−
The parameters P and Q are used for defining unavailable
state
−
Value range is 5-15 s
−
Default value is 10 s
•
The parameter N1
EN/LZT 123 2697
R5A
1998-08-13
209 (306)
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