Cisco 15216 EDFA2 Operation Manual page 217

Chapter 10 Troubleshooting
Possible causes for this alarm are:
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10.1.2.3 LPOUT (Loss of Output Power) Alarm
This alarm is valid only when the ONS 15216 EDFA2 is in OPWR mode, which is rare because this
mode applies to few applications and is generally not recommended. This alarm occurs if the unit is in
OPWR mode and the output power is deviating more than the value of LPOUTDEV from the value of
LPOUTSETPT. The value of LPOUTHYST is used to clear the alarm. Use RTRV-TH-DWDM to find
the threshold values.
If both LPOUT and GAIN or LOS alarm conditions occur at the same time, only the GAIN or LOS alarm
is generated via TL1.
Possible causes for this alarm are:
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78-16033-01
F I N A L D R A F T - C I S C O C O N F I D E N T I A L
Input power is out of range: Verify that for the current gain setting, the input power is within the
range. For example, if the Gain = 22, then the input range is –27 to –5 dBm. Every dB taken from
the Gain is added to the input range, so if the Gain =21, then the input range is –26 to –4 dBm.
VOA attenuation is drifting out of range: Verify that the VOA set value approximately equals the
VOA current value.
To determine this, you must use the ASH shell. You can begin an ASH Telnet session using the IP
address of the ONS 15216 EDFA2 followed by port 8023.
telnet ONS_15216_EDFA2_IP_Address 8023
The following formula provides the setting of the VOA attenuation:
"VOA set value (in units of 10 dB)" =
"snmp attribute get local cerent15216EdfaPumpStatusGain 1" –
"snmp attribute get local cerent15216EdfaConstGainOverallGain"
The value of cerent15216EdfaPumpStatusGain 1 is the fixed gain of the amplifier module. The value
of cerent15216EdfaConstGainOverallGain is the set target gain. Note that the minimum VOA value
is approximately 1 dB, which corresponds to the maximum Gain of approximately 22 dB.
The following formula provides the current value of the VOA attenuation:
"VOA current value (in units of 100 dB)" =
"snmp attribute get local cerent15216EdfaInPowerdBm" –
"snmp attribute get local cerent15216EdfaPumpStatusInPowerdBm 1"
The value of cerent15216EdfaInPowerdBm (INPWRDBM) is the current signal power at the input
before the VOA. The value of cerent15216EdfaPumpStatusInPowerdBm 1 is the signal power after
the VOA.
If the "VOA set value" is different than "VOA current value" by more than a typical variation of up
to 0.5 dB, the unit must be returned to Cisco for repair.
The input power may be too low to achieve the output power setting: Reduce the value of
PUMP2CTRLVALUE using the ED-DWDM command until the alarm clears.
The LPOUTDEV value may be set too low for practical use: Increase the value of LPOUTDEV
using the RTRV-TH-DWDM command.
Cisco ONS 15216 EDFA2 Operations Guide
Alarm Indicators
10-5