Cisco ONS 15454 Troubleshooting Manual page 96

1.10.2 Faulty Fiber-Optic Connections
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 Cisco ONS 15454 Procedure Guide. If possible, do this for the OC-N
card you are working on and the far-end card.
b. Clean the optical connectors on the card. Clean the connectors according to site practice or, if none
exists, follow the procedure 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.
d. Replace the far-end transmitting OC-N card to eliminate the possibility of a degrading transmitter
on this OC-N card.
Removing a card that currently carries traffic on one or more ports can cause a traffic hit. To avoid this,
Caution
perform an external switch if a switch has not already occurred. Consult the Cisco ONS 15454 Procedure
Guide for information.
e. If the power level still falls below the specified range with the replacement fibers and replacement
card, check for one of these three factors that attenuate the power level and affect link loss (LL):
•
•
•
Note
If no power level shows on the fiber, the fiber is bad or the transmitter on the OC-N card failed.
Step 5
a. Check that the Tx and Rx fibers are not reversed. LOS and EOC alarms normally accompany
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 Cisco ONS 15454 Procedure Guide. If possible, do this for the OC-N
card you are working on and the far-end card.
c. Retest the fiber power level.
If the replacement fiber still shows no power, replace the OC-N card.
d.
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. Consult the Cisco ONS 15454 Procedure
Guide for information.
If the power level on the fiber is above the range specified for the card, ensure that an ONS LR card is
Step 6
not being used when an ONS IR card is appropriate.
Cisco ONS 15454 Troubleshooting Guide, R4.6
1-96
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.
Chapter 1 General Troubleshooting
November 2004