Nortel NT1R20, Description

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NT5D11 Line-side T1 Interface Card Page 115 of 290
Line cards Description
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Alarm Level 2 (AL2)
consists of activity with an error threshold above
the AL2 setting. This is deemed to be an unsatisfactory condition. In this
situation, the external alarm hardware will be activated by closing the
normally open contact, the RED ALARM LED on the faceplate will
light, an alarm message will be created in the alarm log and the MMI
terminal, the line-side T1 card will enter line processing mode, and a
yellow alarm message will be sent to the CPE/CSU. Line processing will
send the Meridian 1 either all “on-hook” or all “off-hook” signals,
depending on the dip switch setting of the card.
When you use the Set Alarm command, you will be prompted to set the
threshold level and duration period for alarm levels 1 and 2.
The threshold value indicates the number of bit errors detected per second
that is necessary to activate the alarm. The T1 link processes at a rate of
approximately 1.5 mb/s. The threshold value can be set between 3 and 9 and
can be different for each alarm level. Any other value entered will cause the
software to display a “Parameter Invalid” message. The threshold number
that you enter represents the respective power of 10 as shown in Table 28.
Note: The error rate threshold for a level 2 alarm must be greater (a
smaller power of 10) than for a level 1 alarm.
Table 28
T1 bit error rate threshold settings
Alarm Threshold
bit errors per second
in Power of 10
Threshold
to set alarm
Allowable
Duration Periods
10
–3
1,500/second 1–21 seconds
10
–4
150/second 1–218 seconds
10
–5
15/second 1–2148 seconds
10
–6
1.5/second 1–3600 seconds
10
–7
1.5/10 seconds 10–3600 seconds
10
–8
1.5/100 seconds 100–3600 seconds
10
–9
1.5/1000 seconds 1000–3600 seconds