Specifications

2-30
Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 2 General Troubleshooting
Warning Follow all directions and warning labels when working with optical fibers. To prevent eye
damage, never look directly into a fiber or connector. Class IIIb laser. Danger, laser radiation
when open. The OC-192 laser is off when the safety key is off (labeled 0). The laser is on when the
card is booted and the safety key is in the on position (labeled 1). The port does not have to be in
service for the laser to be on. Avoid direct exposure to the beam. Invisible radiation is emitted from
the aperture at the end of the fiber optic cable when connected, but not terminated.
Procedure: Verify Fiber-Optic Connections
Step 1 Ensure that a single-mode fiber connects to the ONS 15454 OC-N card.
SM or SM Fiber should be printed on the fiber span. ONS 15454 OC-N cards do not use multimode fiber.
Step 2 Check that the connector keys on the SC fiber connector are properly aligned and locked.
Step 3 Check that the single-mode fiber power level is within the specified range:
a. Remove the receive (Rx) end of the suspect fiber.
b. Connect the receive end of the suspect fiber to a fiber-optic power meter, such as a GN Nettest
LP-5000.
c. Determine the power level of fiber with the fiber-optic power meter.
d. Verify that the power level falls within the range specified for the card; see the “Optical Card
Transmit and Receive Levels” section on page 2-35.
Step 4 If the power level falls below the specified range:
a. Clean or replace the fiber patch cords. 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. 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.
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):
– 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.
Note 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.