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Cisco ONS 15327 Troubleshooting Guide, R3.4
March 2004
Chapter2 Alarm Troubleshooting
Alarm Procedures
For UPSR protected circuits, the BER threshold on the ONS 15327 is user provisionable and has a range
for SD from 10–9 to 10–5. For BLSR 1+1 and unprotected circuits, the BER threshold value is not user
provisionable and the error rate is hard-coded to 10–6.
On UPSR, an SD-P condition causes a switch from the working card to the p rotect card at the path (S TS)
level. On BLSR 1+1 or on unprotected circuits, an SD-P condition does not cause switching.
The BER increase that causes the alarm is sometimes caused by a physical fiber problem such as a poor
fiber connection, a bend in the fiber that exceeds the permitted ben d r adi us, or a b ad fiber spl ice.
Signal degrade and signal fail both monitor the incoming BER and are similar alarms, but SD is triggered
at a lower bit error rate than SF. SD causes the card to switch from working to protect. The SD alarm
clears when the BER level falls to one-tenth of the threshold level that triggered the alarm.

Procedure: Clear the SD-P Condition

Step 1 Complete the “Clear the SD Condition” procedure on page 2-105.
Step 2 If the condition does not clear, log onto http://www.cisco.com/tac for more information or call TAC
(1-800-553-2447).
2.6.151 SF
•Not Alarmed (NA), Non-Service Affecting (NSA)
A Signal Fail (SF) condition occurs when the quality of the signal is so poor that the BER on the
incoming optical line passed the signal failure threshold. Signal failure is defined by Telcordia as a “hard
failure” condition. The SD condition (see page 2-104) and SF both monitor the incoming BER er ror ra te
and are similar conditions, but SF is triggered at a higher BER than SD.
The BER threshold on the ONS 15327 is user provisionable and has a range for SF from 10-5 to 10-3.
SF-L causes a switch from the working card to the protect card at the line (facility) level. A line or
facility level SF condition travels on the B2 byte of the SONET overhead.
SF causes a card to switch from working to protect at either the path or line level. The SF condition clears
when the BER level falls to one-tenth of the threshold level that triggered the condition. A BER increase
is sometimes caused by a physical fiber problem, including a poor fiber conne ctio n, a b en d in the fiber
that exceeds the permitted bend radius, or a bad fiber splice.

Procedure: Clear the SF Condition

Step 1 Complete the “Clear the SD Condition” procedure on page 2-105.
Step 2 If the condition does not clear, log onto http://www.cisco.com/tac for more information or call TAC
(1-800-553-2447).
2.6.152 SF-L
•Not Alarmed (NA), Non-Service Affecting (NSA)