Cisco ONS 15454 Troubleshooting Manual page 185

Chapter 1 General Troubleshooting
Step 2 Ensure that the connector keys on the SC fiber connector are properly aligned and locked.
Check that the single-mode fiber power level is within the specified range:
Step 3
Remove the Rx end of the suspect fiber.
a.
Connect the Rx end of the suspect fiber to a fiber-optic power meter, such as a GN Nettest LP-5000.
b.
Determine the power level of fiber with the fiber-optic power meter.
c.
Verify that the power meter is set to the appropriate wavelength for the OC-N card being tested
d.
(either 1310 nm or 1550 nm depending on the specific card).
Verify that the power level falls within the range specified for the card if it is an OC-N card; see the
e.
"1.12.3 OC-N Card Transmit and Receive Levels" section on page
If the power level falls below the specified range for the OC-N card:
Step 4
Clean or replace the fiber patch cords. Clean the fiber according to site practice or, if none exists,
a.
follow the procedure in the "Maintain the Node" chapter in the Cisco ONS 15454 Procedure Guide.
If possible, do this for the OC-N card you are working on and the far-end card.
Clean the optical connectors on the card. Clean the connectors according to site practice or, if none
b.
exists, follow the procedure in the "Maintain the Node" chapter in the Cisco ONS 15454 Procedure
Guide. If possible, do this for the OC-N card you are working on and the far-end card.
c. Ensure that the far-end transmitting card is not an ONS intermediate-range (IR) card when an ONS
long-range (LR) card is appropriate.
IR cards transmit a lower output power than LR cards.
Replace the far-end transmitting OC-N card to eliminate the possibility of a degrading transmitter
d.
on this OC-N card.
Caution Removing a card that currently carries traffic on one or more ports can cause a traffic hit. To avoid this,
perform an external switch if a switch has not already occurred. See the procedures in the
"2.9.2 Protection Switching, Lock Initiation, and Clearing" section on page
information, refer to the "Maintain the Node" chapter in the Cisco ONS 15454 Procedure Guide.
If the power level still falls below the specified range with the replacement fibers and replacement
e.
card, check for one of these three factors that attenuate the power level and affect link loss (LL):
Note
Step 5 If no power level shows on the fiber, the fiber is bad or the transmitter on the OC-N card failed.
Check that the Tx and Rx fibers are not reversed. LOS and EOC alarms normally accompany
a.
reversed Tx and Rx fibers. Switching reversed Tx and Rx fibers clears the alarms and restores the
signal.
Clean or replace the fiber patch cords. Clean the fiber according to site practice or, if none exists,
b.
follow the procedure in the "Maintain the Node" chapter in the Cisco ONS 15454 Procedure Guide.
If possible, do this for the OC-N card you are working on and the far-end card.
November 2009
Excessive fiber distance; single-mode fiber attenuates at approximately 0.5 dB/km.
•
Excessive number or fiber connectors; connectors take approximately 0.5 dB each.
•
Excessive number of fiber splices; splices take approximately 0.5 dB each.
•
These are typical attenuation values. Refer to the specific product documentation for the
actual values or use an optical time domain reflectometer (OTDR) to establish precise link
loss and budget requirements.
1.12.2 Faulty Fiber-Optic Connections
1-146.
2-262. For more
Cisco ONS 15454 Troubleshooting Guide, R8.5
1-141