Cisco ONS 15600 SDH Troubleshooting Manual page 103

Chapter 1 General Troubleshooting
Ensure that the OGI fiber connector is properly aligned and locked.
Step 2
Verify that the single-mode fiber optical-line power level coming into the breakout panel is within the
Step 3
specified range:
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 the fiber with the fiber-optic power meter.
c.
Verify that the power meter is set to the appropriate wavelength for the optical (STM-N) card you
d.
are testing (either 1310 nm or 1550 nm depending on the specific card).
Verify that the power level falls within the range specified for the card; see the
e.
Card Transmit and Receive Levels" section on page
•
•
Step 4 If the power level falls below the specified range:
Note
Clean or replace the OGI fiber fan-out cables. If possible, do this for the optical (STM-N) card you
a.
are working on and the far-end card. Refer to the Cisco ONS 15600 SDH Procedure Guide for fiber
cleaning procedures.
b. Clean the optical connectors on the card. If possible, do this for the optical (STM-N) card you are
working on and the far-end card. Refer to the Cisco ONS 15600 SDH Procedure Guide for fiber
cleaning procedures.
Replace the far-end transmitting optical (STM-N) card to eliminate the possibility of a degrading
c.
transmitter on the far-end optical (STM-N) card.
If the power level still falls below the specified range with the replacement fibers and replacement
d.
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 STM-N port failed.
Step 5
Check that the Tx and Rx fibers are not reversed. LOS and EOC alarms normally accompany
a.
reversed Tx and Rx fibers. Fixing reversed Tx and Rx fibers clears the alarms and restores the signal.
Clean or replace the OGI fiber fan-out cables. If possible, do this for both the STM-N port you are
b.
working on and the far-end STM-N port. Refer to the Cisco ONS 15600 SDH Procedure Guide for
fiber cleaning procedures.
c. Retest the fiber power level.
d. If the replacement fiber still shows no power, replace the optical (STM-N) card.
July 2010
If the power level is within tolerance, the problem is with the fan-out cables or the optical
(STM-N) card.
If the power level is too high, add the appropriate attenuation.
When this condition occurs, the far-end node is usually an ONS 15454 SDH.
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.
1.9.2 Faulty Fiber-Optic Connections
1-74.
Cisco ONS 15600 SDH Troubleshooting Guide, R8.0
"1.9.3 Optical Traffic
1-71